Process for producing a stream comprising ethylene glycol
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34 claims: 23 independent, 11 dependent
- 1Procedimento per la produzione di una miscela bassobollente comprendente glicole etilenico e glicole propilenico, in cui il procedimento comprende le fasi di:a. idrogenare un flusso liquido di zucchero derivato da una biomassa ligno-cellulosica di partenza, detto flusso liquido di zucchero comprendendo acqua e almeno uno zucchero monomero solubilizzato, portando a contatto il flusso liquido di zucchero con un catalizzatore di idrogenazione in presenza di idrogeno, a una pressione di idrogenazione nel campo da 30 bar a 150 bar e una temperatura di idrogenazione nel campo da 50°C a 200°C, e per un tempo di idrogenazione sufficiente a produrre una miscela idrogenata comprendente acqua e almeno un alcole da zucchero;b. eseguire l’idrogenolisi di almeno una porzione della miscela idrogenata, portando a contatto la almeno una porzione di miscela idrogenata con un catalizzatore di idrogenolisi in presenza di ioni OH - e idrogeno, a una pressione di idrogenolisi nel campo da 40 bar a 170 bar, con una temperatura di idrogenolisi e per un tempo di idrogenolisi sufficienti a produrre una miscela di idrogenolisi, com -1prendente glicole etilenico, glicole propilenico e glicerolo;c. separare almeno una porzione della miscela di idrogenolisi in almeno una miscela bassobollente comprendente glicole etilenico e glicole propilenico, e una miscela altobollente comprendente glicerolo;d. reforming di almeno una porzione della miscela altobollente, portando a contatto la almeno una porzione di miscela altobollente con un catalizzatore di reforming in condizioni di reforming e per un tempo di reforming sufficienti a produrre un gas di reforming comprendente idrogeno da reforming, in cui l'idrogeno della fase di idrogenazione e/oppure l'idrogeno della fase di idrogenolisi comprende almeno una porzione dell'idrogeno da reforming.
- 2Procedimento secondo la rivendicazione 1, in cui il rapporto percentuale della quantità di idrogeno da reforming nella fase di idrogenazione rispetto alla quantità totale di idrogeno nella fase di idrogenazione è superiore a un valore scelto dal gruppo costituito da 10%, 30%, 50%, 60%, 70%, 80%, 90% e 95%.
- 3Procedimento secondo una qualsiasi delle rivendicazioni 1 e 2, in cui il rapporto percentuale della quantità di idrogeno da reforming nella fase di idrogenolisi rispetto alla quantità totale di idrogeno nella fase di idrogenolisi è superiore a un valore scelto dal gruppo costituito da 10%, 30%, 50%, 60%, 70%, 80%, 90% e 95%.
- 4Procedimento secondo una qualsiasi delle rivendicazioni 1 a 3, in cui la quantità percentuale di glicerolo nella miscela di idrogenolisi è un valore in un campo scelto dal gruppo costituito dal 5% al 40%, dal 10% al 30% e dal 15% al 20% in peso su base di sostanza secca.
- 5Procedimento secondo la rivendicazione 1, in cui la temperatura di idrogenolisi è un valore in un campo scelto dal gruppo costituito da 150°C a 240°C, e da 190°C a 220°C.
- 6Procedimento secondo la rivendicazione 5, in cui la pressione di idrogenolisi è un valore in un campo scelto dal gruppo costituito da 40 bar a 150 bar, da 50 bar a 100 bar, e da 60 a 80 bar.
- 7Procedimento secondo una qualsiasi delle rivendicazioni 5 a 6, in cui il rapporto molare della quantità totale degli alcoli zuccheri rispetto alla quantità di idrogeno nella fase di idroge -3nolisi è un valore in un campo scelto dal gruppo costituito da 1:2 a 1:10, da 1:3 a 1:8, e da 1:4 a 1:6.
- 8Procedimento secondo una qualsiasi delle rivendicazioni 5 a 7, in cui la fase di idrogenolisi si verifica in modo discontinuo e il tempo di idrogenolisi è un valore in un campo scelto dal gruppo costituito da 10 minuti a 10 ore, da 20 minuti a 8 ore, da 30 minuti a 7 ore, da 45 minuti a 6 ore, da 60 minuti a 4 ore, e da 90 minuti a 3 ore.
- 9Procedimento secondo una qualsiasi delle rivendicazioni 5 a 7, in cui la fase di idrogenolisi si verifica in un modo continuo o semicontinuo avente una velocità spaziale oraria liquida di idrogenolisi, e la velocità spaziale oraria liquida di idrogenolisi ha un valore in un campo scelto dal gruppo costituito da 0,1 a 4 h -1 , 0,2 a 3 h -1 , 0,5 a 2,5 h -1 , e 1 a 2 h -1 .
- 10Procedimento secondo una qualsiasi delle rivendicazioni 5 a 9, in cui il catalizzatore di idrogenolisi è un catalizzatore metallico supportato comprendente almeno un metallo scelto dal gruppo costituito da Ru, Ni, Cu e Pt, o loro combinazioni.
- 11Procedimento secondo la rivendicazione 10, -4in cui il supporto comprende almeno un composto scelto dal gruppo costituito da allumina, ossido di zirconio e carbone attivato, oppure una loro combinazione.
- 12Procedimento secondo una qualsiasi delle rivendicazioni 1 a 11, in cui la temperatura di idrogenazione è un valore in un campo scelto dal gruppo costituito da 70°C a 150°C, da 85°C a 130°C, e da 100 a 120°C.
- 13Procedimento secondo una qualsiasi delle rivendicazioni 1 a 12, in cui la pressione di idrogenazione è un valore in un campo scelto dal gruppo costituito da 40 bar a 150 bar, da 50 bar a 100 bar, e da 60 a 80 bar.
- 14Procedimento secondo una qualsiasi delle rivendicazioni 1 a 13, in cui il rapporto molare della quantità totale di zuccheri monomeri solubilizzati rispetto alla quantità di idrogeno nella fase di idrogenazione è un valore in un campo scelto dal gruppo costituito da 1:2 a 1:10, da 1:3 a 1:8, e da 1:4 a 1:6.
- 15Procedimento secondo una qualsiasi delle rivendicazioni 1 a 14, in cui la fase di idrogenazione si verifica in modo discontinuo e il tempo di idrogenazione è un valore in un campo scelto dal -5gruppo costituito da 30 minuti a 240 minuti, da 45 minuti a 180 minuti, e da 60 minuti a 120 minuti.
- 16Procedimento secondo una qualsiasi delle rivendicazioni 1 a 14, in cui la fase di idrogenazione si verifica in modo continuo o semicontinuo avente una velocità spaziale oraria liquida di idrogenazione, e la velocità spaziale oraria liquida di idrogenazione è un valore in un campo scelto dal gruppo costituito da 0,2 a 3 h -1 , da 0,5 a 2,5 h -1 , e da 1 a 2 h -1 .
- 17Procedimento secondo una qualsiasi delle rivendicazioni 1 a 16, in cui il catalizzatore di idrogenazione è un catalizzatore metallico supportato, comprendente almeno un metallo scelto dal gruppo costituito da Ru, Ni e Pt, o loro combinazioni.
- 18Procedimento secondo la rivendicazione 17, in cui il supporto comprende almeno un composto scelto dal gruppo costituito da allumina, ossido di zirconio e carbone attivato, oppure una loro combinazione.
- 19Procedimento secondo una qualsiasi delle rivendicazioni 1 a 18, in cui il reforming viene eseguito in fase acquosa in condizioni di reforming in fase acquosa.
- 20Procedimento secondo la rivendicazione 19, in cui le condizioni di reforming in fase acquosa comprendono una temperatura di reforming, e la temperatura di reforming è un valore in un campo scelto dal gruppo costituito da 100°C a 400°C, da 150°C a 350°C, e da 200°C a 300°C.
- 21Procedimento secondo la rivendicazione 20, in cui le condizioni di reforming in fase acquosa comprendono una pressione di reforming, e la pressione di reforming viene scelta in modo da mantenere almeno una porzione dei polioli altobollenti nella miscela ad alto punto di ebollizione allo stato liquido alla temperatura di reforming.
- 22Procedimento secondo una qualsiasi delle rivendicazioni 19 a 21, in cui l'acqua viene aggiunta alla miscela altobollente.
- 23Procedimento secondo una qualsiasi delle rivendicazioni 19 a 22, in cui il catalizzatore di reforming è un catalizzatore metallico supportato comprendente almeno un metallo scelto dal gruppo costituito da Pt, Ru, Re, Pd, Rh, Ni e Co, o loro combinazioni.
- 24Procedimento secondo la rivendicazione 23, in cui il supporto comprende almeno un composto scelto dal gruppo costituito da allumina, carbone -7attivato, silice, zeolite, ossido di titanio, ossido di zirconio e ossido di cerio, oppure una loro combinazione.
- 25Procedimento secondo una qualsiasi delle rivendicazioni 19 a 24, in cui la fase di reforming si verifica in modo continuo o semicontinuo avente una velocità spaziale oraria liquida di reforming, e la velocità spaziale oraria liquida di reforming è un valore in un campo scelto dal gruppo costituito da 0,1 a 10 h -1 , da 0,5 a 10 h -1 , da 1 a 10 h -1 , da 2 a 10 h -1 , da 4 a 8 h -1 , e da 5 a 7 h -1 .
- 26Procedimento secondo una qualsiasi delle rivendicazioni 1 a 25, in cui le fasi a), b) e d) vengono realizzate in tre reattori separati.
- 27Procedimento secondo una qualsiasi delle rivendicazioni 1 a 26, in cui l’almeno un alcole da zucchero comprende un composto scelto dal gruppo costituito da xilitolo, sorbitolo e arabitolo, o loro miscele.
- 28Procedimento secondo una qualsiasi delle rivendicazioni 1 a 27, in cui l’almeno uno zucchero monomero solubilizzato comprende un composto scelto dal gruppo costituito da xilosio, glucosio e arabinosio, o loro miscele.
- 29Procedimento secondo la rivendicazione 28, -8in cui l'almeno uno zucchero monomero solubilizzato comprende xilosio e la quantità percentuale in peso di xilosio su base secca nel flusso di zucchero liquido, è superiore a un valore scelto dal gruppo costituito da 50%, 70%, 80%, 90% e 95%.
- 30Procedimento secondo una qualsiasi delle rivendicazioni 1 a 29, in cui almeno una parte del glicole etilenico e almeno una parte del glicole propilenico nella miscela bassobollente vengono separate dalla miscela bassobollente per produrre un flusso di glicole etilenico comprendente glicole etilenico e un flusso di glicole propilenico comprendente glicole propilenico.
- 31Procedimento secondo la rivendicazione 30, in cui il flusso di glicole etilenico comprende inoltre almeno un diolo scelto dal gruppo costituito da 1,2-propilenglicole, 1,2-butandiolo e 1,2pentandiolo.
- 32Procedimento secondo una qualsiasi delle rivendicazioni 30 e 31, in cui il flusso di glicole etilenico viene usato per la produzione di una resina poliestere.
- 33Procedimento secondo la rivendicazione 32, in cui il poliestere comprende parti di acido e almeno l'85% molare delle parti di acido è derivato -9da acido tereftalico o suo dimetilestere.
- 34Procedimento secondo una qualsiasi delle rivendicazioni 32 a 33, in cui la resina poliestere viene usata per produrre bottiglie di poliestere.
Independent claims34
388 paragraphs in 5 sections, as filed
DESCRIPTION
BACKGROUND
Biomass conversion has attracted significant attention as a key technology for replacing petroleum as a renewable source of fuels and chemicals. Lignocellulose is the most abundant biomass resource and is indigestible by humans, which is an advantage over sugars and starch, as the use of edible carbohydrates competes with food production. Thus, lignocellulose is one of the most interesting biomass resources in nature, available at very low cost.
To effectively replace fossil oil, renewable fuels and chemicals must not only meet the
-1FC/ap technical specifications in terms of performance, but must be produced at a competitive cost compared to petroleum-based competitors.
Ethylene glycol and propylene glycol are two petroleum-derived polyols that are widely used as starting materials for polymer chemistry. Many processes have been developed to convert water-soluble and insoluble sugar sources into polyols. However, although the conversion chemistry is well understood, none of the prior art processes have yet proven industrially viable. Some of the prior art processes have demonstrated the conversion of synthetic sugars to lightweight polyols; in the case of the conversion of sugars derived from lignocellulose, the prior art processes produce polyol blends that have poor properties for real-world use and are generally too expensive to compete with petroleum-derived polyols. One of the main problems is that it is difficult to control the competing reaction pathways, so the stream obtained from the lignocellulosic starting product is a mixture that usually includes many compounds.
-2One of the main problems in converting sugars to polyols is the cost of the hydrogen used in the reactions. In actual conversion plants, on-site hydrogen production systems have been installed. The most economical solution is methane reforming, which is not a renewable hydrogen source; water electrolysis is a source of hydrogen but is expensive. Another strategy involves locating polyol conversion plants near oil refineries, where hydrogen is produced during the refining process. Although low-cost, this solution uses petroleum-derived hydrogen, and actual implementation is limited by the availability of refinery sites.
An exemplary previous technique for converting biomass-derived xylose to xylitol, in H. M. Baudel et al., “Xylitol production via catalytic hydrogenation of sugarcane bagasse dissolving pulp liquid effluents over Ru/C catalyst”, J. Chem. Technol. Biotechnol. 80: 230-233 (2005), xylose-rich liquid effluents generated by acid hydrolysis of sugarcane bagasse for dissolving pulp production are
-3 were converted to xylitol, through catalytic hydrogenation over Ru/C. The paper shows that ruthenium (2% Ru/C) as a catalyst is suitable for the conversion of sugars hydrolyzed from bagasse to polyols, with high selectivity towards xylitol (about 98%), even under conditions of moderate temperatures and hydrogen pressure (80°C, 20 atm).
As an exemplary previous technique for the conversion of xylitol to polyols, in J. Sun et al., “Selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol on supported Ru catalysts”, Green Chem., 2011, 13, p. 135, the selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol was carried out on different catalysts in the presence of calcium hydroxide. The catalysts included Ru supported on activated carbon (C) and, for comparison, on metal oxides, Al2O3, TiO2, ZrO2 and Mg2AlOx as well as other noble metals supported on C, such as Rh, Pd and Pt. The authors show how to control the selectivity of the hydrogenolysis of xylitol to different polyols, including ethylene glycol, propylene glycol, glycerol, threitol, arabitol. A significant amount of lactic acid is also obtained as a by-product.
-4US6964757 describes a process for producing hydrogen from oxygenated hydrocarbon reagents, such as methanol, glycerol, sugars (e.g., glucose and xylose), or sugar alcohols (e.g., sorbitol). The process is carried out in the condensed liquid phase. The process involves reacting water and a water-soluble oxygenated hydrocarbon in the presence of a metal-containing catalyst. The catalyst contains a metal selected from the group consisting of Group VIIIB transition metals, their alloys, and mixtures thereof. The process can be performed at lower temperatures than those used in conventional steam reforming of alkanes. Other processes are described in US6699457, US6953873, and US6964758.
US20110313209A1 describes a catalytic process for generating at least one polyol from a starting product comprising cellulose. The process involves continuously contacting hydrogen, water, and a starting product containing cellulose with a catalyst to generate an effluent stream comprising at least one polyol, water, hydrogen, and at least one coproduct. The unreacted hydrogen is recycled to the
-5 reaction zone. Co-products may be reaction intermediates that can be separated from the reaction zone effluent and recycled back to the reaction zone.
US8198486 describes processes for generating propylene glycol, ethylene glycol, and other polyols. The processes involve reacting a first portion of an aqueous stream of a starting biomass in solution over a catalyst under aqueous reforming conditions to produce hydrogen, and then reacting the hydrogen and a second portion of the aqueous starting solution over a catalyst to produce propylene glycol, ethylene glycol, and other polyols. Using a portion of the starting product to produce the hydrogen needed to generate the polyols reduces the overall yield of the process.
There is therefore a need for an improved process for the production of polyols from a starting biomass, optimizing the conversion yield of the starting biomass product to polyols and simultaneously reducing or eliminating the need for external hydrogen.
BRIEF DESCRIPTION OF THE INVENTION
A process for the production is described
-6 of a low-boiling mixture comprising ethylene glycol and propylene glycol, wherein the process comprises the steps of:
to. hydrogenating a liquid sugar stream derived from a starting lignocellulosic biomass, said liquid sugar stream comprising water and at least one solubilized monomer sugar, by contacting the liquid sugar stream with a hydrogenation catalyst in the presence of hydrogen, at a hydrogenation pressure in the range from 30 bar to 150 bar and at a hydrogenation temperature in the range from 50°C to 200°C, and for a hydrogenation time sufficient to produce a hydrogenated mixture comprising water and at least one sugar alcohol;
b. performing hydrogenolysis of at least a portion of the hydrogenated mixture by contacting the at least a portion of the hydrogenated mixture with a hydrogenolysis catalyst in the presence of OH ions<sup>-</sup> and hydrogen, and a hydrogenolysis pressure in the range of 40 bar to 170 bar, at a hydrogenolysis temperature and for a hydrogenolysis time sufficient to produce a hydrogenolysis mixture comprising ethylene glycol, propylene glycol and glycerol;
c. separating at least a portion of the hydrogenolysis mixture into at least one low-boiling mixture comprising ethylene glycol and propylene glycol, and a high-boiling mixture comprising glycerol;
d. reforming at least a portion of the high-boiling mixture by contacting the at least a portion of the high-boiling mixture with a reforming catalyst under reforming conditions and for a reforming time sufficient to produce a gaseous reformed product comprising hydrogen, wherein the hydrogen from the hydrogenation step and/or the hydrogen from the hydrogenolysis step comprises at least a portion of the reformed hydrogen.
It is also described that the percentage ratio of the amount of reforming hydrogen in the hydrogenation step to the total amount of hydrogen in the hydrogenation step may be greater than a value selected from the group consisting of 10%, 30%, 50%, 60%, 70%, 80%, 90% and 95%.
It is also described that the percentage ratio or amount of reforming hydrogen in the hydrogenolysis step compared to the amount to
-8tale of hydrogen in the hydrogenolysis phase can be higher than a value chosen from the group consisting of 10%, 30%, 50%, 60%, 70%, 80%, 90% and 95%.
It is also described that the percentage amount by weight on a dry matter basis of glycerol in the hydrogenolysis mixture may be a value in a range selected from the group consisting of 5% to 40%, 10% to 30% and 15% to 20% of the total amounts of polyols in the hydrogenolysis mixture.
It is further described that the hydrogenolysis temperature can be a value in a range selected from the group consisting of 150°C to 240°C, and 190°C to 220°C.
It is also described that the hydrogenolysis pressure can be a value in a range selected from the group consisting of 40 bar to 150 bar, 50 bar to 100 bar and 60 to 80 bar.
It is also described that the molar ratio of the total amount of sugar alcohols to the amount of hydrogen in the hydrogenolysis step can be a value in a range selected from the group consisting of 1:2 to 1:10, 1:3 to 1:8, and 1:4 to 1:6.
It is also described that the hydrogen phase
-9yes it can be carried out discontinuously and the hydrogenolysis time can be a value in a range chosen from the group consisting of 10 minutes to 10 hours, 20 minutes to 8 hours, 30 minutes to 7 hours, 45 minutes to 6 hours, 60 minutes to 4 hours and 90 minutes to 3 hours.
It is also described that the hydrogenolysis phase can occur continuously or semi-continuously having a hourly space velocity of the hydrogenolysis liquid, and the hourly space velocity of the hydrogenolysis liquid can be a value in a range chosen from the group consisting of 0.1 to 4 h.<sup>-1</sup>, 0.2 to 3 h<sup>-1</sup>, 0.5 to 2.5 h<sup>-1</sup>, and 1 to 2 h<sup>-1</sup>.
It is further described that the hydrogenolysis catalyst may be a supported metal catalyst comprising at least one metal selected from the group consisting of Ru, Ni, Cu and Pt, or combinations thereof.
It is also described that the support may comprise at least one compound selected from the group consisting of alumina, zirconium oxide and activated carbon, or a combination thereof.
It is further described that the hydrogenation temperature can be a value in a range selected from the group consisting of 70°C to 150°C, 85°C to 130°C, and 100 to 120°C.
-10It is also described that the hydrogenation pressure can be a value in a range chosen from the group consisting of 40 bar to 150 bar, 50 bar to 100 bar, and 60 to 80 bar.
It is further described that the molar ratio of the total amount of solubilized monomeric sugars to the amount of hydrogen in the hydrogenation step can be a value in a range selected from the group consisting of 1:2 to 1:10, 1:3 to 1:8, and 1:4 to 1:6.
It is also described that the hydrogenation step can occur discontinuously and the hydrogenation time can be a value in a range chosen from the group consisting of 30 minutes to 240 minutes, 45 minutes to 180 minutes, and 60 minutes to 120 minutes.
It is further described that the hydrogenation step can occur continuously or semi-continuously having a hourly space velocity of the hydrogenation liquid, and the hourly space velocity of the hydrogenation liquid can be a value in a range chosen from the group consisting of 0.2 to 3 h<sup>-1</sup>, from 0.5 to 2.5 h<sup>-1</sup>, and from 1 to 2 h<sup>-1</sup>.
It is also described that the hydrogenation catalyst can be a metal catalyst
-11 supported, comprising at least one metal selected from the group consisting of Ru, Ni, and Pt, or combinations thereof. It is further described that the support may comprise at least one compound selected from the group consisting of alumina, zirconium oxide, and activated carbon, or a combination thereof.
It is also described that reforming can be performed in the aqueous phase under aqueous phase reforming conditions.
It is further disclosed that the aqueous phase reforming conditions may include a reforming temperature, and the reforming temperature may be a value in a range selected from the group consisting of 100°C to 400°C, 150°C to 350°C, and 200°C to 300°C.
It is also disclosed that the aqueous phase reforming conditions may include a reforming pressure and the reforming pressure may be selected to maintain at least a portion of the high boiling polyols in the high boiling mixture in the liquid state at the reforming temperature.
It is further described that water can be added to the high-boiling mixture.
It is also described that the catalyst of re
-12forming may be a supported metal catalyst comprising at least one metal selected from the group consisting of Pt, Ru, Re, Pd, Rh, Ni, and Co, or combinations thereof.
It is further described that the support may comprise at least one compound selected from the group consisting of alumina, activated carbon, silica, zeolite, titanium dioxide, zirconium dioxide, and cerium oxide, or a combination thereof.
It is also described that the reforming step can occur in a continuous or semi-continuous manner having a hourly space velocity of the reforming liquid, and the hourly space velocity of the reforming liquid can be a value in a range selected from the group consisting of 0.1 to 10 h<sup>-1</sup>, from 0.5 to 10 h<sup>-1</sup>, from 1 to 10 h<sup>-1</sup>, from 2 to 10 h<sup>-1</sup>, from 4 to 8 hours<sup>-1</sup>, and from 5 to 7 h<sup>-1</sup>.
It is further described that the hydrogenation, hydrogenolysis and reforming steps can be carried out in three separate vessels.
It is also described that at least one sugar alcohol may comprise a compound selected from the group consisting of xylitol, sorbitol and arabitol, or mixtures thereof.
It is further described that at least one sugar
-13Solubilized monomer may comprise a compound selected from the group consisting of xylose, glucose, and arabinose, or mixtures thereof.
It is also disclosed that at least one solubilized monomeric sugar may comprise xylose and the percentage amount by weight of xylose relative to the dry matter in the liquid sugar stream may be greater than a value selected from the group consisting of 50%, 70%, 80%, 90% and 95%.
It is further disclosed that at least a portion of the ethylene glycol and at least a portion of the propylene glycol in the low-boiling mixture are separated from the low-boiling mixture to produce an ethylene glycol stream comprising ethylene glycol and a propylene glycol stream comprising propylene glycol.
It is also disclosed that the ethylene glycol stream may further comprise at least one diol selected from the group consisting of 1,2-propylene glycol, 1,2-butanediol, and 1,2-pentanediol.
It is further described that the ethylene glycol stream can be used for the production of a polyester resin.
It is further described that the polyester may comprise acidic parts and at least 85 mol% of the
-14 parts of the acid can be derived from terephthalic acid or its dimethyl ester.
It is further described that polyester resin can be used to produce a polyester bottle.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 is a diagram illustrating an implementation of the described procedure.
Figure 2 is a diagram illustrating another embodiment of the described process.
Figure 3 is a schematic diagram illustrating one embodiment of the process for the conversion of the lignocellulosic starting product to the liquid sugar stream.
DETAILED DESCRIPTION
The process described involves the catalytic conversion of a liquid sugar stream to a low-boiling mixture of ethylene glycol and propylene glycol. The liquid sugar stream is subjected to a hydrogenation reaction in the presence of hydrogen and a hydrogenation catalyst to produce a hydrogenated mixture comprising one or more sugar alcohols. The hydrogenated mixture is then reacted with hydrogen in the presence of a hydrogen catalyst.
-15nolysis to produce a hydrogenolysis mixture, including ethylene glycol, propylene glycol and glycerol.
According to one aspect of the invention, a process is described for the production of a mixture comprising ethylene glycol and propylene glycol from a lignocellulosic starting product without the need, or with the need for a limited amount, of external hydrogen, which represents an important result in the economy of the process. Specifically, the hydrogenolysis mixture is separated into at least one low-boiling mixture and one high-boiling mixture, preferably by thermal processes, such as evaporation. Other streams may be produced during the separation step. In the context of this disclosure, low-boiling compounds are compounds that can be evaporated and recovered in the evaporated condensate when the hydrogenolysis mixture is heated to 120°C at a pressure of 50 mbar. The low-boiling mixture comprises ethylene glycol and propylene glycol, and may also comprise other polyols, such as butanediol, pentanediols, and/or other compounds that are not polyols, such as products that do not have
-16reacted or intermediates or by-products. In the context of this description, high-boiling compounds are compounds that can be recovered in the condensate when the hydrogenolysis mixture is heated to 120°C at a pressure of 50 mbar. The high-boiling mixture includes glycerol and may also include other polyols, such as threitol and erythritol, and/or other compounds that are not polyols, such as lactic acid, formic acid (which in a basic environment may be present in an anionic form, such as sodium lactate and sodium formate), and unreacted sugar alcohols that have not evaporated under the separation conditions.
The high-boiling mixture is then converted to hydrogen under reforming conditions, and the hydrogen is used to fuel the hydrogenation and/or hydrogenolysis reactions. The high-boiling mixture is an unavoidable by-product of the process described for the production of the low-boiling mixture comprising ethylene glycol and propylene glycol. Therefore, its use for the generation of at least a portion of the hydrogen required for the catalytic conversion should not affect the yield of the described process.
-17Preferably, reforming is performed under aqueous liquid phase conditions of the high-boiling mixture in a reactor separate from the hydrogenation and hydrogenolysis reaction reactor or reactors separate from the hydrogenation and hydrogenolysis reaction reactor, to avoid any contamination of the hydrogenation and hydrogenolysis catalysts by the reforming mixture and by-products. Then, according to another aspect of the invention, a process is described which improves the lifetime of the catalyst.
In a preferred embodiment, the liquid sugar stream is derived from the lignocellulosic starting product by economical imbibition in water, which solubilizes a portion of the carbohydrates in the starting product without the need for chemicals or catalysts. The solid, unsolubilized starting product can then be used to feed another conversion process or conversion processes to different chemical end products. Imbibition of the lignocellulosic starting product produces a stream of imbibition liquid comprising soluble sugars, derived primarily from xylans of the starting product.
-18ligno-cellulosic, which can be hydrolyzed to monomers and purified before introducing them into the process of this description.
Thus, according to another aspect of the invention, a process is described that converts, at low cost, a liquid sugar stream to important chemicals while reducing conversion costs.
Lignocellulosic starting product
In general, a lignocellulosic starting product, also referred to as lignocellulosic biomass, can be described as follows:
Aside from starch, the three main constituents of plant biomass are cellulose, hemicellulose, and lignin, which are commonly referred to by the generic term lignocellulose. Polysaccharide-containing biomass, as a generic term, encompasses both starch and lignocellulosic biomass. Therefore, certain types of starting products can be plant biomass, polysaccharide-containing biomass, and lignocellulosic biomass, which may or may not contain starch.
Polysaccharide-containing biomasses according to the present invention include any material containing polymeric sugars, for example
-19in the form of starch as well as refined starch, cellulose and hemicellulose.
Relevant types of lignocellulosic starting products for carrying out the claimed invention may include biomass derived from agricultural crops selected from the group consisting of starch-containing grains, refined starch; corn silage, bagasse, straw, e.g., from rice, wheat, oats, rye, barley, rapeseed, sorghum; softwood such as Pinus sylvestris, Pinus radiate; hardwood, e.g., Salix spp., Eucalyptus spp.; Tubers such as sugar beets, potatoes, cereals obtained for example from rice, wheat, rye, oats, barley, rapeseed, sorghum, and corn; waste paper, fibrous fractions from biogas treatment operations, natural fertilizer, palm oil processing residues, municipal solid waste, or the like. Although the experiments are limited to some examples from the above-mentioned list, the invention is believed to be applicable to all members of the list.
In one embodiment, the starting product of lignocellulosic biomass used in the process comes from the family commonly called grasses. The exact name is the name of the family known as Poaceae or Gramineae of the
-20 class Liliopsida (monocots) of flowering plants. Plants in this family are commonly called grasses or, to distinguish them from other graminoids, true grasses. Bamboo is also included. There are approximately 600 genera and approximately 9,000 to 10,000 or more species of grasses (Kew Index of World Grass Species).
The Poaceae family includes the world's major food grains and cereals, meadow grasses and forage grasses, and bamboo. Poaceae generally have hollow stems called culms, which are closed (solid) at intervals called nodes, the points along the culm where the leaves grow. The leaves of grasses are usually alternate, distichous (in one plane), or rarely spiral-shaped and with parallel veins. Each leaf is differentiated into a lower sheath that encircles the stem for a certain length and a blade with margins. The leaf blades of many grasses are hardened with siliceous phytoliths, which help deter grazing animals. In some grasses (such as gladiolus), this makes the edges of the grass blades sharp enough to cut human skin. At the junction between the sheath
-21e the blade is covered with a membranous appendage or fringe of hairs, called the ligula, which prevents water or insects from penetrating the sheath.
Grass blades grow from the base of the blade, not from elongated stem tips. This low growing point evolved in response to grazing animals and allows the grasses to be grazed or mowed regularly without serious damage to the plant.
The flowers of the Poaceae family are typically arranged in spikelets, each of which contains one or more florets (the spikelets are also grouped in panicles or ears). A spikelet consists of two (or sometimes fewer) bracts at the base, called glumes, followed by one or more florets. A floret consists of the flower surrounded by two bracts called the lemma (the outer one) and the palea (the inner one). Flowers are usually hermaphroditic (maize, which is monoecious, is an exception), and pollination is almost always anemophilous. The perianth is reduced to two bracts, called lodicules, which expand and contract to shed the lemma and palea; these are generally interpreted as modified sepals.
-22The fruit of the Poaceae is a caryopsis, in which the seed coat is fused to the fruit wall and therefore cannot be separated from it (as in the corn seed).
There are three general classifications of the growth habit of grasses: the bunch type (also called caespitose), the stoloniferous type, and the rhizomatous type.
The success of grasses is due partly to their morphology and growth processes, and partly to their physiological diversity. Most grasses fall into two physiological groups, using the C3 and C4 photosynthesis pathways for carbon fixation. C4 grasses have a photosynthesis pathway linked to the anatomy of their specialized Kranz leaf, which makes them particularly suited to warm climates and a low-carbon atmosphere.
C3 grasses are referred to as “cool-season grasses,” while C4 plants are considered “warm-season grasses.” Grasses can be either annual or perennial. Examples of cool-season annual grasses are wheat, rye, annual bluegrass, and oats.
-23 Examples of cool-season perennial grasses include orchard grasses (Dactylis glomerata), Festuca spp., Kentucky bluegrass, and Lolium perenne. Examples of warm-season annual grasses include corn, Sorgum bicolor, and pearl millet. Examples of warm-season perennial grasses include Andropogon gerardii, Indian grass, couch grass, and switchgrass.
The classification of the grass family recognizes 12 subfamilies: these are 1) Anomochlooideae, a small lineage of broad-leaved grasses that includes two genera (Anomochloa, Streptochaeta); 2) Pharoideae, a small lineage of grasses that includes three genera, including Pharus and Leptaspis; 3) Puelioideae, a small lineage that includes the African genus Puelia; 4) Pooideae which includes wheat, barley, oats, Bronnus and Calamagrostis; 5) Bambusoideae which includes bamboo; 6) Ehrhartoideae, which includes rice and wild rice; 7) Arundinoideae, which includes the giant reed and the common reed; 8) Centothecoideae, a small subfamily of 11 genera which is sometimes included in Panicoideae; 9) Chloridoideae which includes Eragrostis, about 350 species, including teff, Sporobolus, about 160 species, Eleusine coracana (L.) Gaertn., and Muhlenbergia, about 175
-24 species; 10) Panicoideae including panicle grass, corn, sorghum, sugarcane, most millets, Digitaria and Andropogon gerardii; 11) Micrairoideae and 12) Danthoniodieae, including pampas grass; with Poa being a genus of about 500 species of grasses, native to temperate regions of both hemispheres.
Agricultural grasses grown for their edible seeds are called cereals. Three common cereals are rice, wheat, and corn. Of all crops, 70% are grasses.
Sugarcane is the main source of sugar production. Grasses are used for construction. Bamboo scaffolding can withstand typhoon-force winds that could demolish steel scaffolding. Larger bamboos and Arundo donax have sturdy stems that can be used similarly to lumber, and grass roots stabilize the turf of sod and brushwood huts. Arundo is used to make reeds for wind instruments, and bamboo is used in countless creations.
Another starting product of lignocellulosic biomass can be constituted by plants
-25wood or timber. A woody plant is a plant that uses wood as its structural tissue. These are typically perennials whose trunks and larger roots are strengthened with wood produced by the vascular tissue. The main trunk, larger branches, and roots of these plants are normally covered by a layer of thick bark. Woody plants are usually trees, shrubs, or lianas. Wood is a structural cellular adaptation that allows the woody plant to grow from stems planted in the ground year after year, thus making woody plants the largest and tallest plants.
These plants require a vascular system to transfer water and nutrients from the roots to the leaves (xylem) and to transfer sugars from the leaves to the rest of the plant (phloem). There are two types of xylem: primary xylem, which is formed during primary growth by the procambium, and secondary xylem, which is formed during secondary growth by the vascular cambium.
What is normally called wood is the secondary xylem of these plants.
The two main groups in which secondary xylem can be found are:
1) Conifers (Coniferae): There are approximately 600 species of conifers. All species have secondary xylem, which is relatively uniform in structure throughout this group. Many conifers grow into tall trees; the secondary xylem of these trees is sold as softwood.
2) Angiosperms (Angiospermae): There are approximately 250,000 to 400,000 species of angiosperms. In this group, secondary xylem is not found in monocots (e.g., Poaceae). Many non-monocot angiosperms grow into trees, and the secondary xylem of these is sold commercially as hardwood.
The term softwood is used to describe wood obtained from trees belonging to the gymnosperm family. Gymnosperms are plants with naked seeds that are not enclosed in an ovary. These seed fruits are considered more primitive than hardwoods or deciduous woods. Softwood trees are typically evergreen, form cones, and have needle-like leaves or bracts. They include coniferous species such as pine, spruce, fir, and cedar. The hardness of the wood varies from one species of conifer to another.
The expression hardwood (broadleaf wood)
-27 is used to describe wood from trees belonging to the angiosperm family. Angiosperms are plants with ovules enclosed in an ovary for protection. When fertilized, these ovules develop into seeds. Hardwood trees are typically broadleaf; in temperate and northern latitudes, they are mostly deciduous, but in the tropics and subtropics, they are mostly evergreen. Their leaves can be simple (single-bladed) or compound with leaflets attached to the stem. Although they vary in shape, all hardwood tree leaves have a distinct network of fine veins. Hardwood trees include, for example, aspen, birch, cherry, maple, oak, and teak.
Thus, in one embodiment, a suitable lignocellulosic biomass may be selected from the group consisting of grasses and wood. In one embodiment, the lignocellulosic biomass may be selected from the group consisting of plants belonging to the conifers, angiosperms, Poaceae, and related families. Another preferred lignocellulosic biomass may be biomass having at least 10% of its dry matter weight as cellulose.
-28sa, or more preferably at least 5% by weight of its dry substance as cellulose.
Liquid sugar stream derived from lignocellulosic starting product
The liquid sugar stream is derived from the lignocellulosic starting product by a treatment, or pre-treatment, of the lignocellulosic starting product.
Pretreatment of lignocellulosic biomass is used to solubilize and remove carbohydrates, mainly xylans and glucans, from the lignocellulosic starting product, while at the same time the concentration of harmful inhibitory by-products such as acetic acid, furfural, and hydroxymethylfurfural remains substantially low.
The pretreatment techniques that can be used are well known in the field and include physical, chemical, and biological pretreatment techniques, or any combination thereof. In preferred embodiments, the pretreatment of lignocellulosic biomass is performed in a batch or continuous process.
Physical pre-treatment techniques include various types of grinding/comminution (particle size reduction), irradiation
-29Crushing/comminution includes grinding in a dry or wet vibrating ball mill.
Although not required or preferred, chemical pretreatment techniques include acid, dilute acid, base, organic solvent, lime, ammonia, sulfur dioxide, carbon dioxide, pH-controlled hydrothermolysis, wet oxidation, and solvent treatment.
If the chemical treatment process is an acid treatment, a continuous dilute treatment or a mild acid treatment, such as sulfuric acid, or another organic acid, such as acetic acid, citric acid, tartaric acid, succinic acid, or any mixture thereof, is more preferable. Other acids may also be used. A moderate acid treatment means at least in the context of the invention that the pH of the treatment is in a range from 1 to 5, preferably from 1 to 3.
In one specific embodiment, the acid concentration is in the range of 0.1 to 2.0% by weight of acid, preferably sulfuric acid. The acid is mixed or brought into contact with the lignocellulosic biomass, and the mixture is maintained at a temperature in the range of about 160 to 220°C for
-30a period of time ranging from minutes to seconds. Specifically, pretreatment conditions may be as follows: 165-183°C, 3-12 minutes, 0.5-1.4% (w/w) acid concentration, 15-25, preferably about 20% (w/w) total solids concentration. Other contemplated processes are described in U.S. Patent Nos. 4,880,473, 5,366,558, 5,188,673, 5,705,369, and 6,228,177.
Wet oxidation techniques involve the use of oxidizing agents, such as sulfite-based oxidizers and the like. Examples of solvent treatments include treatments with DMSO (dimethyl sulfoxide) and the like. Chemical treatment processes are generally performed for times of about 5 to 10 minutes, but can be performed for shorter or longer times.
In one embodiment, both chemical and physical pretreatment are performed, including, for example, mild acid treatment and high temperature and pressure treatment. The chemical and physical treatments can be performed sequentially or simultaneously.
Current heat treatment strategies
-31consist of subjecting the lignocellulosic material to temperatures between 110 and 250°C for 1-60 minutes, for example:
hot water extraction
Multi-stage dilute acid hydrolysis, which removes dissolved materials before inhibitors are formed.
Dilute acid hydrolysis at relatively low severity conditions.
Wet alkaline oxidation
Steam explosion
Any pre-treatment with subsequent detoxification.
If hydrothermal pretreatment is chosen, the following conditions are preferred:
Pre-treatment temperature: 110-250°C, preferably 120-240°C, more preferably 130-230°C, more preferably 140-220°C, more preferably 150-210°C, more preferably 160-200°C, even more preferably 170-200°C, or very preferably 180-200°C.
Pre-treatment time: 1-60 minutes, preferably 2-55 minutes, more preferably 3-50 minutes, more preferably 4-45 minutes, more preferably 5-40 minutes, more preferably 5-35
-32 minutes, more preferably 5-30 minutes, more preferably 5-25 minutes, more preferably 5-20 minutes and most preferably 5-15 minutes.
The dry matter content after pretreatment is preferably at least 20% (w/w). Other preferable upper limits are the amount of biomass to water in the pretreated lignocellulosic starting product, which should be in the ratio ranges from 1:4 to 9:1; from 1:3.9 to 9:1, from 1:3.5 to 9:1, from 1:3.25 to 9:1, from 1:3 to 9:1, from 1:2.9 to 9:1, from 1:2 to 9:1, from 1.15 to 9:1, from 1:1 to 9:1, and from 1:0.9 to 9:1.
A preferred embodiment of the process used to obtain the liquid sugar stream from lignocellulosic biomass is shown in Figure 3 and includes a pre-treatment and other treatment steps.
A preferred pretreatment of a lignocellulosic biomass comprises an imbibition of the lignocellulosic biomass starting product and optionally a steam explosion of at least a portion of the imbibed lignocellulosic biomass starting product.
Imbibition is performed in a substance such as
-33water in the form of vapor, water vapor, or liquid, or liquid and vapor combined, to obtain a product. The product is a soaked biomass containing an imbibition liquid, with the imbibition liquid typically being water in its liquid or vapor form, or some mixture.
This imbibition can be performed with any technique that exposes a substance to water, which can be steam, liquid, or a mixture of steam and water, or, more generally, to water at high temperature and high pressure. The temperature must be in one of the following ranges: 145 to 165°C, 120 to 210°C, 140 to 210°C, 150 to 200°C, 155 to 185°C, or 160 to 180°C. Although the time may be long, for example, up to 24 hours, or less than 16 hours, or less than 12 hours, or less than 9 hours, or less than 6 hours, the exposure time is preferably quite short, ranging from one minute to 6 hours, from one minute to 4 hours, from one minute to 3 hours, from one minute to 2.5 hours, more preferably from 5 minutes to 1.5 hours, from 5 minutes to an hour, from 15 minutes to an hour.
If steam is used, it is preferably saturated steam, but it can be superheated. The phase
-34 Imbibition can be batch or continuous, with or without stirring. Low-temperature imbibition can also be used before high-temperature imbibition. The low-temperature imbibition temperature ranges from 25 to 90°C. Although the time may be long, such as up to but less than 24 hours, or less than 16 hours, or less than 12 hours, or less than 9 hours, or less than 6 hours; the exposure time is preferably quite short, ranging from one minute to 6 hours, from one minute to 4 hours, from one minute to 3 hours, from one minute to 2.5 hours, more preferably from 5 minutes to 1.5 hours, from 5 minutes to an hour, and from 15 minutes to an hour.
The imbibition step may also include the addition of other compounds, for example sulfuric acid, ammonia, to achieve superior performance later in the process.
The product comprising the soaking liquid, or soaked liquid, is then passed to a separation step where at least a portion of the soaking liquid is separated from the soaked biomass. The liquid will not be separated completely so at least a portion of the soaking liquid is separated, preferably as much as
-35As much liquid as possible within an economical timeframe. The liquid obtained from this separation step is known as the imbibition liquid stream, which includes the imbibed liquid. The imbibed liquid will be the liquid used in imbibition, generally water and the soluble species of the starting product. These water-soluble species include glucan, xylan, galactan, arabinan, and their monomers and oligomers. Solid biomass is called first solid flow because it contains most, if not all, of the solids.
Separating the soaked liquid can again be done with known techniques and probably with some that have not yet been invented. A preferred piece of equipment is a press, since a press will form a liquid under high pressure.
The first solid stream can then optionally be subjected to steam explosion to create a steam-exploded stream containing solids. Steam explosion is a well-known technique in the biomass field, and any of the currently available and future systems are acceptable for this step. The severity of the steam explosion is known in the literature.
-36as Ro, and is a function of time and temperature and is expressed as
Ro = texp[(T-100)/14.75] with the temperature, T, expressed in degrees Celsius and the time, t, expressed in minutes.
The formula is also expressed as Log(Ro), and precisely
Log(Ro) = Ln(t) + [(T-100)/14.75].
Log(Ro) is preferably in the range 2.8 to 5.3, 3 to 5.3, 3 to 5.0 and 3 to 4.3.
The steam-blasted stream can optionally be washed with at least water, with the possibility of using other additives. It is conceivable that another liquid could be used in the future, so water is not considered absolutely essential. At this point, water is the preferred liquid. The effluent from the washing operation can be added to the soaked liquid stream. This washing step is not considered essential and is optional.
The washed exploded stream is then treated to remove at least a portion of the liquid in the washed exploded material. This separation step is also optional. The phrase "at least a portion is removed" is intended to remind us that
While removing as much liquid as possible is desirable (preferably by pressure), it is unlikely that 100% of the liquid can be removed. In any case, 100% water removal is undesirable, as water is required for the subsequent hydrolysis reaction. The preferred procedure for this step is again pressing, but other known techniques, and those not yet invented, are also considered suitable. The liquid products separated by this process can be added to the soaked liquid stream.
In one embodiment, the lignocellulosic biomass is exposed to a pre-imbibition step prior to an imbibition step in a temperature range of 10°C to 150°C, even more preferably 25°C to 150°C, even more preferably 25°C to 145°C, and 25°C to 100°C and 25°C to 90°C being also preferred ranges. The pre-soaking time may be long, such as up to but preferably less than 48 hours, or less than 24 hours, or less than 16 hours, or less than 12 hours, or less than 9 hours, or less than 6 hours; the exposure time is preferably shorter, ranging from one minute to 6 hours, from one minute to 4 hours, from one minute to 3 hours,
-38from one minute to 2.5 hours, more preferably from 5 minutes to 1.5 hours, 5 minutes to one hour, 15 minutes to one hour.
The pre-soaking step is performed in the presence of a pre-soaked liquid. After soaking, this liquid has preferably removed less than 5% by weight of the total sugars in the raw material, more preferably less than 2.5% by weight of the total sugars in the raw material, with less than 1% by weight of the total sugars in the raw material being most preferred.
This pre-soaking phase is useful as a modification of the soaking phase of the biomass pre-treatment phase. In the imbibition (not pre-imbibition) of biomass in the pre-treatment stages, the imbibition liquid stream that has been separated from the imbibition solids will preferably have a reduced filtrate amount of filter-clogging components, so that the imbibition liquid can be readily purified, preferably by at least one technique selected from the chromatography, nanofiltration, and ultrafiltration group. Although a single purification step is represented in Figure 3, as ul
-39th step of the process for deriving the liquid sugar stream from lignocellulosic biomass, the imbibed liquid stream can be subjected to more than one purification step, which can be done before hydrolysis or decationization.
The imbibed liquid stream will include water, sugars comprising monomeric and oligomeric sugars, salts that are dissociated into anions and cations in the imbibed liquid stream, optionally phenols, furfural, oils, and acetic acid. The imbibed liquid stream will primarily contain xylooligomers.
Ideally, the total sugar concentration in the imbibed liquid stream should be in the range of 0.1 to 300 g/L, with 50 to 290 g/L being the most preferred range, and 75 to 280 g/L being even more preferred, with 100 to 250 g/L being the most preferred. This concentration can be achieved by removing water. A 50% removal of water increases the concentration of the non-aqueous species twofold. While various concentration increments are acceptable, in one embodiment at least a two-fold increase in the xylooligomer concentration in the
-40imbibed liquid flow is achieved. In one embodiment, at least a 4-fold increase in the xylooligomer concentration in the imbibed liquid is achieved. In one embodiment, at least a 6-fold increase in the xylooligomer concentration in the imbibed liquid flow is achieved. Multiple concentration steps can be adopted for the imbibed liquid flow before or after each exemplary process step described in Figure 3.
In a preferred embodiment, the imbibed liquid stream is subjected to hydrolysis to convert at least some of the oligomers present in the imbibed liquid stream into monomers. The hydrolysis of the oligomers can be achieved by contacting the imbibed liquid stream with a hydrolysis catalyst under hydrolytic conditions. The hydrolysis catalyst can be an inorganic acid, such as sulfuric acid, or an enzyme or a cocktail of enzymes. The hydrolysis conditions will vary depending on the catalyst chosen, and are well known in the art.
A preferred way to achieve hydrolysis of the imbibed liquid stream comprises at least two steps, according to the teachings of WO2013026849. The
-41The first step involves creating an acid flow from the imbibed liquid stream. This is accomplished by increasing the amount of H+ ions in the imbibed liquid stream to create the acid flow. Once the desired pH is achieved, the next step hydrolyzes the oligosaccharides in the acid flow by increasing the temperature of the acid flow to a hydrolysis temperature for the hydrolysis reaction, thus creating a hydrolyzed flow.
While the creation of the acid flow can be done in any way that increases the concentration of H ions<sup>+</sup>, a preferred embodiment is to take advantage of the salt content of the imbibed liquid stream. To achieve the acidity required for the hydrolysis step, the salt content in the imbibed liquid stream can be reduced through cation exchange while simultaneously replacing the cations with H ions.<sup>+</sup>While salts may occur naturally in the imbibed liquid stream, they may also be added as part of the pre-treatment process or before or during the creation of the acid stream.
In one embodiment, the hydrolyzed stream is a clearer liquid, containing almost exclusively
-42 monomeric sugars, with a low salt content and low quantity of degradation products that can prevent subsequent chemical or biological transformations of the sugars.
In a preferred embodiment, the liquid sugar stream comprises at least a portion of the hydrolyzed stream.
In another preferred embodiment, the liquid sugar stream consists of at least a portion of the hydrolyzed stream.
Catalytic conversion of liquid sugar stream to polyols
The liquid sugar stream is converted to a mixture comprising polyols in a catalytic reaction comprising at least two steps, both of which are performed in the presence of hydrogen.
Figure 1 shows an exemplary embodiment of the described process. The liquid sugar stream is introduced into a hydrogenation reactor and brought into contact with a hydrogenation catalyst and hydrogen under hydrogenation conditions, promoting the hydrogenation of the sugars in the liquid sugar stream. The hydrogenation catalyst is preferably a supported metal comprising at least one metal
-43 chosen from the group of Ru, Ni, and Pt, or combinations thereof. The catalyst support may include alumina, zirconium oxide, or activated carbon, or a combination thereof. The ratio between the total amount of sugars in the liquid sugar stream and the amount of hydrogenation catalyst is preferably between 3:2 and 3:0.5.
Preferably, the hydrogenation reaction is performed at a hydrogenation temperature that promotes the conversion of all, or virtually all, of the sugars in the liquid sugar stream. The hydrogenation temperature is between 50°C and 200°C, preferably between 70°C and 150°C, more preferably between 85°C and 130°C, and most preferably between 100°C and 120°C.
The hydrogenation reaction can be performed in batches and for a hydrogenation time sufficient to convert all, or substantially all, of the sugars present in the liquid sugar stream. The hydrogenation time is preferably between 30 minutes and 240 minutes, more preferably between 45 minutes and 180 minutes, and even more preferably between 60 minutes and 120 minutes. The catalyst is preferably present in particulate form and dispersed in the liquid sugar stream.
-44do so as to effectively promote the hydrogenation reaction. The contents of the hydrogenation reactor can be stirred during the reaction.
In another embodiment, the hydrogenation reaction is performed continuously or semi-continuously, in which the liquid sugar stream is fed into the hydrogenation reactor and/or the hydrogenated mixture is removed from the reactor continuously or semi-continuously. The continuous or semi-continuous hydrogenation reaction can be characterized by a liquid hydrogenation hourly space velocity of 0.2 to 3 h.<sup>-1</sup>, preferably 0.5 to 2.5 h<sup>-1</sup>, most preferably 1 to 2 hours<sup>-1</sup>The continuous or semi-continuous hydrogenation reaction can be performed in a CSTR reactor, with the catalyst preferably present in particulate form and dispersed in the liquid sugar stream under mechanical stirring. A preferred continuous or semi-continuous hydrogenation is in a fixed-bed reactor configuration, although the hydrogenation reaction can also be performed in a fluidized-bed reactor. The liquid sugar stream, the hydrogenation catalyst and the hydrogen can be introduced
-45ducted into the hydrogenation reactor separately from different inlets or they can be premixed before being introduced into the reactor.
The hydrogenation reaction is performed in the presence of hydrogen, at a hydrogenation pressure in the range of 30 bar to 150 bar, preferably in the range of 40 bar to 150 bar, more preferably in the range of 50 bar to 100 bar, and most preferably in the range of 60 bar to 80 bar. In the case of batch hydrogenation, the hydrogenation pressure corresponds to the pressure at which hydrogen is introduced into the reactor, at a temperature of 25°C. Experimentally, it is measured using a pressure gauge mounted on the gaseous hydrogen feed line, at the inlet of the hydrogenation reactor and immediately before the reactor shuts down. The actual reaction pressure in the reactor may differ from the hydrogenation pressure due to the temperature, the presence of reaction gases produced, and the vapor pressure of the liquid sugar stream at the hydrogenation temperature. In case the hydrogenation is performed continuously or semi-continuously, where the flow of hydrogen gas must be
-46nire adjusted to control the pressure inside the reactor, the hydrogenation pressure is the actual pressure inside the reactor at the reaction temperature.
Preferably, hydrogen and the liquid sugar stream are introduced into the hydrogenation reactor in amounts suitable to achieve a molar ratio of the total amount of solubilized monomer sugar to the amount of hydrogen in a range of 1:2 to 1:10, more preferably 1:3 to 1:8, and most preferably 1:4 to 1:6. Since the reaction prefers stoichiometric excess hydrogen to effectively promote the hydrogenation reaction, a portion of the hydrogen will not react and can be recycled at the end of the reaction and reused in the total conversion process. In the case of a batch reaction, the total amount of hydrogen and the total amount of liquid sugar flow are introduced into the reactor, which is then closed. In the case of continuous or semi-continuous mode, the hydrogen and the liquid sugar flow are introduced continuously or semi-continuously, preferably according to the fields described.
In a preferred embodiment, the flow li
-47Sugar liquid comprises xylose, glucose, and arabinose, or a mixture, and the hydrogenation reaction of the sugars produces a hydrogenated mixture containing at least one sugar alcohol. Preferred sugar alcohols are xylitol, sorbitol, and arabitol, or mixtures thereof.
In a preferred embodiment, the liquid sugar stream is derived from the lignocellulosic starting product by solubilizing primarily the xylans of the lignocellulosic starting product. Thus, the sugars in the sugar liquid stream mainly comprise xylose, and the preferred amount of xylose in the sugar liquid stream on a dry basis is greater than 50%, more preferably greater than 70%, even more preferably greater than 80%, and even more preferably greater than 90%, with the highest preference being for an amount greater than 95%. The corresponding hydrogenated mixture shall mainly comprise xylitol, and the preferred amount of xylitol in the hydrogenated mixture on a dry basis is greater than 45%, more preferably greater than 70%, still more preferably greater than 80%, still more preferably greater than 90%, the most preferred value being greater than 95%.
-48The hydrogenated mixture is then removed from the hydrogenation reactor and introduced into the hydrogenolysis reactor. If the hydrogenation catalyst is present in the form of dispersed particles, it is at least partially removed from the reactor along with the hydrogenated mixture and can be recovered, for example, by filtration and returned to the hydrogenation reactor, possibly after regeneration. Eventually, unwanted hydrogenation products can also be removed from the hydrogenated mixture.
The hydrogenated mixture is introduced into a hydrogenolysis reactor and brought into contact with a hydrogenolysis catalyst and hydrogen and hydrogenolysis conditions such as to promote the hydrogenolysis of the sugar alcohols in the hydrogenated mixture. The hydrogenolysis catalyst preferably comprises a supported metal selected from the group of Ru, Ni, and Pt, or combinations thereof. The catalyst support may include alumina, zirconium oxide, or activated carbon, or a combination thereof. The ratio between the total amount of alcohols in the hydrogenated mixture and the amount of hydrogenolysis catalyst is preferably between 3:2 and 3:0.1.
-49The hydrogenolysis reaction of alcohols prepared from sugars occurs in the presence of OH ions<sup>-</sup> which influence the pH of the reaction environment. pH values above 9, corresponding to basic conditions, promote the effective hydrogenolysis of alcohols prepared from sugars. OH ions<sup>-</sup> they are preferably derived from a compound selected from the group consisting of NaOH, KOH, Ca(OH)<sub>2</sub> and Ba(OH)<sub>2</sub>, or a combination thereof. The source of OH ions<sup>-</sup> It can be introduced into the hydrogenolysis reactor or it can be added to the hydrogenated mixture before insertion into the reactor.
The hydrogenolysis reaction is carried out at a hydrogenolysis temperature that promotes the conversion of alcohols in the hydrogenated mixture. The hydrogenolysis temperature can be between 150°C and 240°C, and more preferably between 190°C and 220°C.
The hydrogenolysis reaction can be carried out in a batch manner and for a hydrogenolysis time that is preferably sufficient to convert all, or practically all, of the sugar alcohols present in the hydrogenated mixture. The hydrogenolysis time is preferably between 10 minutes and 10 hours, more preferably between 20 minutes and 8 or
-50 hours, even more preferably between 30 minutes and 7 hours, even more preferably between 45 minutes and 6 hours, most preferably between 60 minutes and 4 hours, and even more preferably between 90 minutes and 3 hours. The hydrogenolysis catalyst is preferably present in particulate form and dispersed in the hydrogenated mixture to effectively promote the hydrogenolysis reaction. The contents of the hydrogenolysis reactor must be stirred during the reaction.
In another embodiment, the hydrogenolysis reaction is performed continuously or semi-continuously, in which the hydrogenated mixture is fed into the hydrogenation reactor and/or the hydrogenolysis mixture is removed from the reactor continuously or semi-continuously. The continuous or semi-continuous hydrogenolysis reaction can be characterized by an hourly space velocity of the hydrogenolysis liquid ranging from 0.1 to 4 h.<sup>-1</sup>, preferably 0.2 to 3 h<sup>-1</sup>, more preferably 0.5 to 2.5 h<sup>-1</sup> and with the highest preference from 1 to 2 hours<sup>-1</sup>The continuous or semi-continuous hydrogenolysis reaction can be carried out in a CSTR reactor, the hydrogenolysis catalyst being preferably present in particulate form and dispersed in the
-51 hydrogenated mixture in the presence of mechanical stirring. A preferred continuous or semi-continuous hydrogenolysis configuration is a fixed-bed reactor, although the hydrogenolysis reaction can also be performed in a fluidized-bed reactor. The hydrogenated mixture, the hydrogenolysis catalyst, and the hydrogen can be introduced into the hydrogenolysis reactor separately from different inlets or can be premixed before introduction into the reactor.
The hydrogenolysis reaction is carried out in the presence of hydrogen at a hydrogenolysis pressure in the range of 40 bar to 170 bar, preferably in the range of 40 bar to 150 bar, more preferably in the range of 50 bar to 100 bar, with the highest preference in the range of 60 bar to 80 bar. In the case of hydrogenolysis performed in a batch mode, the hydrogenolysis pressure corresponds to the pressure at which hydrogen is introduced into the reactor, at a temperature of 25°C. Experimentally, it is measured with a pressure gauge mounted on the gaseous hydrogen feed pipe, at the inlet of the hydrogenolysis reactor and immediately before the reactor shuts down. The actual reaction pressure in the reactor
-52 may differ from the hydrogenolysis pressure due to the temperature and the contribution of the gaseous reaction products and the vapor pressure of the liquids at the hydrogenolysis temperature. In the case of hydrogenolysis performed semi-continuously or continuously, in which the flow of gaseous hydrogen must be regulated to control the pressure inside the reactor, the hydrogenolysis pressure is the actual pressure inside the reactor at the reaction temperature.
Preferably, hydrogen and the hydrogenated mixture are introduced into the hydrogenolysis reactor in amounts suitable to achieve a molar ratio between the total amount of sugar alcohols and the amount of hydrogen in a range from 1:2 to 1:10, more preferably from 1:3 to 1:8, and most preferably from 1:4 to 1:6. Since the reaction preferably occurs in a stoichiometric excess of hydrogen to effectively promote the hydrogenolysis reaction, a portion of the hydrogen will not react and can be recycled at the end of the reaction and reused in the total conversion process. In the case of a batch reaction, the total amount of hydrogen and the total amount of hydrogenated mixture are introduced into the reactor which is
-53ne then closed. In the case of continuous or semi-continuous mode, the hydrogen and the hydrogenated mixture are introduced continuously or semi-continuously, preferably according to the fields described.
The hydrogenolysis reaction of sugar alcohols in the hydrogenated mixture produces a hydrogenolysis mixture comprising water, ethylene glycol, propylene glycol, and glycerol. It may also include other polyols, unwanted compounds such as lactic acid or formic acid, and unreacted sugar alcohols.
The hydrogenolysis mixture is then removed from the hydrogenolysis reactor. If the hydrogenolysis catalyst is present in the form of dispersed particles, it is at least partially removed from the reactor along with the hydrogenolysis mixture and can be recovered, for example, by filtration and recharged into the hydrogenolysis reactor, possibly after regeneration.
The hydrogenolysis mixture is then separated into at least one low-boiling mixture comprising water, ethylene glycol, and propylene glycol, and a high-boiling mixture, comprising water, glycerol, and possibly lactic acid and unreacted sugar alcohols.
-54Although any process known in the art and not yet invented can be used for the separation of the hydrogenolysis mixture, the preferred method is thermal evaporation. Preferably, the evaporation is carried out at a temperature between 100°C and 140°C and a pressure between 30 mbar and 200 mbar, more preferably at a temperature of 120°C and a pressure of 50 mbar.
According to this disclosure, the high-boiling mixture is then introduced into a reforming reactor and contacted with a reforming catalyst under reforming conditions that promote the transformation of organic compounds in the high-boiling mixture. In this disclosure, reforming refers to the general reaction of an organic compound and water to yield a liquid reforming product and a gaseous reforming product. The liquid reformer product is in the liquid state at a temperature of 25°C and a pressure of 1 bar. The gaseous reformer product comprises reformer hydrogen and may also include methane, carbon monoxide, carbon dioxide, and light alkanes such as ethane and propane. The liquid reformer product comprises water and may also include organic products.
-55 intermediates of the reforming reaction.
The reforming of the high-boiling mixture can be performed in the gas phase, according to well-known steam reforming.
Preferably, the reforming of the high-boiling mixture is performed under aqueous reforming conditions, where the high-boiling compounds in the high-boiling mixture react with liquid water under aqueous reforming conditions in the presence of a reforming catalyst. The aqueous reforming catalyst preferably comprises a supported metal selected from the group of Pt, Ru, Re, Pd, Rh, Ni, and Co, or combinations thereof. The catalyst support may include alumina, activated carbon, silica, zeolite, titanium oxide, zirconium oxide, and cerium oxide, or a combination thereof.
The aqueous reforming reaction is preferably carried out at a reforming temperature that promotes the conversion of all, or virtually all, of the organic compounds present in the high-boiling mixture. The aqueous reforming temperature can be between 100°C and 400°C, preferably between 150°C and 350°C, and most preferably between 200°C and 300°C.
-56The aqueous reforming reaction is performed at a reforming pressure that is preferably sufficient to maintain at least a portion of the high-boiling compounds in the high-boiling polyol mixture in the liquid state at the reforming temperature. The reforming pressure is achieved using an inert gas, which is a gas that does not participate in the reforming reaction. Preferably, the inert gas is nitrogen.
The reforming reaction is preferably carried out continuously or semi-continuously, in which the high-boiling mixture is introduced into the reforming reactor and/or the reforming products are removed from the reactor continuously or semi-continuously. The continuous or semi-continuous reforming reaction can be characterized by a liquid reforming hourly space velocity of 0.1 to 10 h.<sup>-1</sup>, preferably 0.5 to 10 h<sup>-1</sup>, more preferably from 1 to 10 h<sup>-1</sup>, even more preferably from 2 to 10 h<sup>-1</sup>, even more preferably from 4 to 8 h<sup>-1</sup>, most preferably 5 to 7 h<sup>-1</sup>The continuous or semi-continuous reforming reaction can be carried out in a CSTR reactor, the catalyst preferably being present in the form of particles.
-57 cells and dispersed in the high-boiling mixture under mechanical stirring. A continuous or semi-continuous reforming configuration is a fixed-bed reactor, although the reforming reaction can also be performed in a fluidized-bed reactor. The high-boiling mixture, reforming catalyst, and inert gas can be introduced into the reforming reactor separately from different inlets or can be premixed before introduction into the reactor.
The reformed hydrogen is reused to supply at least a portion of the hydrogen required in the hydrogenation step or the hydrogenolysis step, or both. An external hydrogen source can be used to supply the remaining portion of the required hydrogen.
When reformed hydrogen is used to feed the hydrogenation stage, the percentage ratio of the amount of reformed hydrogen in the hydrogenation stage to the total amount of hydrogen in the hydrogenation stage is greater than a value selected from the group consisting of 10%, 30%, 50%, 60%, 70%, 80%, 90%, and 95%, with the remaining portion being fed from the external hydrogen source.
-58When reformed hydrogen is used to feed the hydrogenolysis stage, the percentage ratio of the amount of reformed hydrogen in the hydrogenolysis stage to the total amount of hydrogen in the hydrogenolysis stage is greater than a value selected from the group consisting of 10%, 30%, 50%, 60%, 70%, 80%, 90%, and 95%, the remaining portion being fed from the external hydrogen source.
In a preferred embodiment, all the hydrogen required for the hydrogenation and hydrogenolysis reaction is provided by reforming the high-boiling polyol mixture. The hydrogenation step is preferably performed under hydrogenation conditions to convert all, or substantially all, of the sugars present in the liquid sugar stream to a hydrogenated mixture, i.e., with a hydrogenation conversion yield of 100% or substantially 100%. In the described process, the hydrogenolysis step is preferably carried out under hydrogenolysis conditions suitable for producing a sufficient amount of high-boiling compounds to generate a sufficient amount of reforming hydrogen to feed the entire conversion process. Therefore, in the realization
-59preferred method, the described process for producing the light polyol blend is hydrogen self-sufficient. As is evident from the experimental section, the amount of high-boiling compounds produced in the hydrogenolysis step can be varied and controlled by appropriately selecting hydrogenolysis parameters, such as hydrogenolysis temperature and pH.
In a preferred embodiment, the hydrogenolysis conditions are selected to control the amount of glycerol in the hydrogenolysis mixture. The percentage of glycerol in the hydrogenolysis mixture may be greater than a value selected from the group consisting of 5% to 40%, 10% to 30%, and 15% to 20% by weight on a dry matter basis.
In another preferred embodiment of the described process, schematically represented in Figure 2, after the hydrogenolysis step the hydrogenolysis mixture is removed from the hydrogenolysis reactor together with the unreacted hydrogen and the gaseous hydrogenolysis products and subjected to a gas/liquid separation step, preferably at a temperature lower than the hydrogenolysis temperature, more preferably at a temperature
-60°C below 100°C, with most preference being given to temperatures below 50°C. Unreacted hydrogen and the gaseous products of hydrogenolysis may be sent to a first hydrogen separation stage, where the hydrogen is purified and then recycled to the hydrogenation and/or hydrogenolysis reaction.
Some of the water in the hydrogenolysis mixture can then be removed through a dehydration step. Dehydration can be accomplished by thermal evaporation or filtration. Preferably, the dry matter content of the dehydrated glycol mixture ranges from 40% to 95%, more preferably from 50% to 90%, even more preferably from 60% to 85%, and most preferably from 70% to 80%.
After separation of the hydrogenolysis mixture into at least the low-boiling mixture and the high-boiling mixture, water may be added to the high-boiling mixture before the reforming stage to achieve a dry matter content of at least 30%, more preferably at least 50%, and most preferably at least 60%. Preferably, the added water is recycled water from the dehydration stage.
-61In one embodiment, the pH of the high-boiling mixture may be varied prior to reforming, for example by adding hydrochloric acid, to achieve a pH that is preferably between 7 and 9.
After the reforming stage, the resulting reforming gas and the liquid reforming products are separated in a gas/liquid separation stage. The gaseous products enter a second hydrogen separation stage to purify the reforming hydrogen and then use it in the hydrogenation and/or hydrogenolysis reaction. Preferably, the first hydrogen separation stage and the second hydrogen separation stage are performed in the same equipment.
The liquid reformer products may include unreacted heavy polyols or intermediate reformers and may be fed back into the reformer and further reformed.
Use
An ethylene glycol stream and a propylene glycol stream may be separated from the low-boiling polyol mixture by any process known in the art or
-62to be invented, preferably by distillation. Optionally, other streams are produced during the separation.
The propylene glycol stream includes propylene glycol and may also include small amounts of ethylene glycol or other low-boiling polyols.
The ethylene glycol stream comprises a plurality of diols, where ethylene glycol is the major component, since the amount of ethylene glycol, expressed as a molar percentage with respect to the plurality of diols, is preferably greater than 80%. In preferred embodiments, the molar amount of ethylene glycol is greater than 85%, preferably greater than 90%, and more preferably greater than 95%, with greater than 98% being the most preferable value.
In one embodiment, the ethylene glycol stream further comprises at least one diol selected from 1,2-propylene glycol, 1,2-butanediol, and 1,2-pentanediol.
In a preferred embodiment, the ethylene glycol stream comprises 1,2-propylene glycol, and the molar percentage of 1,2-propylene glycol based on the plurality of diols is preferably in
-63less than 15%, more preferably less than 12%, still more preferably less than 10%, still more preferably less than 7%, and still more preferably less than 5%, most preferably less than 3%, the still most preferred value being less than 2%.
In another preferred embodiment, the ethylene glycol stream comprises 1,2-butanediol, and the percentage amount of 1,2-butanediol relative to the plurality of diols is preferably less than 10%, more preferably less than 8%, still more preferably less than 5%, still more preferably less than 3%, more preferably less than 2%, and most preferably less than 1%.
In a preferred embodiment, the ethylene glycol stream comprises 1,2-pentanediol, and the percentage amount of 1,2-pentanediol relative to the plurality of diols is preferably less than 5%, more preferably less than 4%, still more preferably less than 3%, and still more preferably less than 2%, and most preferably less than 1%.
Although the ethylene glycol stream may comprise only one 1,2-diol, more preferable
-64It usually comprises only two 1,2-diols, and even more preferably it comprises three 1,2-diols. Most preferably, the ethylene glycol stream comprises 1,2-propylene glycol, 1,2-butanediol, and 1,2-pentanediol.
Ethylene glycol stream can be used to produce a polyester resin.
A first preferred process for producing polyester resin involves ester treatment, including ester exchange and polycondensation. Essentially, the diols of a plurality of diols are reacted with a dicarboxylic acid ester (such as dimethyl terephthalate) in an ester exchange reaction, which can be catalyzed by an ester exchange catalyst. When alcohol is formed in the reaction (methanol when using dimethyl terephthalate), it may be necessary to remove the alcohol to convert all or almost all of the reactants to monomers. The monomers then undergo polycondensation, and the catalyst used in this reaction is generally a compound of antimony, germanium, or titanium, or a mixture thereof. The ester exchange catalyst may be sequestered to prevent
-65yellowing of the polymer by introducing a phosphorus compound, for example polyphosphoric acid, at the end of the ester exchange reaction.
A second preferred process for producing polyester resin is the acid process, which involves direct esterification and polycondensation. Essentially, the diols of a plurality of diols are reacted with an acid (such as terephthalic acid) via a direct esterification reaction, producing a monomer and water, which is removed to complete the reaction. The direct esterification step does not require a catalyst. Similar to the ester process, the monomers then undergo polycondensation to form polyester.
In both processes, the polyester can be further polymerized to a higher molecular weight by solid-phase polymerization, which is particularly useful for container (bottle) applications.
In a preferred embodiment, at least 85% of the acid moieties of the polyester are derived from terephthalic acid or its dimethyl ester.
Examples
-66Preparing a liquid sugar stream
Two different wheat straw starting products and one Arundo Donax starting product were used as the lignocellulosic starting product to produce three liquid sugar streams (stream 1 and stream 2 from wheat straw and stream 3 from Arundo Donax) used in the catalytic conversion experiments.
Each lignocellulosic starting product was subjected to a pre-soaking step in water at a temperature of 130°C for 30 minutes with a liquid-to-solid ratio of 5:1.
The pre-soaked lignocellulosic starting product was subjected to an imbibition step, and the imbibed starting product was separated by a press to produce imbibition liquid and a stream of imbibed solids containing the imbibed biomass. The stream of imbibed solids was subjected to steam explosion to create a stream of steam-exploded product. The liquids were separated from the steam-exploded flow using a press and added to the imbibition liquid. Table 1 lists the parameters used in the imbibition phase and the steam explosion.
<td></td><td colspan="2">Imbibition phase</td><td colspan="2">Steam explosion</td>
<td></td><td>Temperature (°C)</td><td>Time (minutes)</td><td>Temperature (°C)</td><td>Time (minutes)</td>
<td>Wheat straw</td><td> 155</td><td> 65</td><td> 190</td><td> 4</td>
<td>Arundo Donax</td><td> 155</td><td> 155</td><td> 195</td><td> 4</td>
Table 1. Parameters used in the steam imbibition and explosion phase.
The soaked liquid was subjected to a solids separation step to remove solids by centrifugation and macrofiltration (bag filter with a 1-micron filter size). Centrifugation was performed using an Alfa Laval CLARA 80 centrifuge at 8000 rpm. A clarified liquid was separated from the suspended solids.
The clarified liquid was then subjected to an initial nanofiltration phase using an Alfa Laval 3.8" device (membrane code NF3838/48), which separates the incoming flow into two streams: the retentate and the permeate. Nanofiltration was performed according to the following procedure.
The stability of the permeate flow was checked by rinsing with demineralized water at 50°C and 10 bar. The permeate flow rate was measured. A quantity of 1800 L of clarified liquid was added to the feed tank. Before filtration, the system was rinsed for 5 minutes, without pressure, to remove water. The system was brought to operating conditions (pressure: 20 bar, temperature: 45°C). The retentate stream was recycled into the feed tank and the permeate stream was discharged. The test continued until the liquid volume in the feed tank was reduced to 50% of the initial soaked liquid volume, corresponding to 900 L of permeate and 900 L of retentate. The previous procedure produced a first nanofiltrated retentate and a first nanofiltrated permeate.
The first retentate liquid was diluted by adding a volume of water corresponding to 50% of its volume and subjected to a second first nanofiltration phase, according to the same procedure used in the first nanofiltration phase.
The second nanofiltration produced a second nanofiltrated permeate and a liquid flow
-69purified.
The purified liquid stream was subjected to a decationization step to produce a decationized liquid having a reduced amount of salts, by inserting the purified liquid stream into a column containing an ion exchange resin (Relite EXC14) at a flow rate of 240 L/h and a temperature of 25°C. The decationization was performed with a contact time of 3.5 BVH (bed volume per hour).
Each decationized liquid stream was subjected to hydrolysis in a continuous reactor under the conditions reported in Table 2.
<td></td><td>pH</td><td>Temperature (°C)</td><td>Time to stay (minutes)</td>
<td>Liquid flow decationized 1</td><td> 1,75</td><td> 150</td><td> 8,3</td>
<td>Liquid flow decationized 2</td><td> 1,34</td><td> 146</td><td> 4,3</td>
<td>Liquid flow decationized 3</td><td> 1,33</td><td> 145</td><td> 4,2</td>
Table 2. Hydrolysis conditions of the three streams of decationized liquid.
Each stream of hydrolyzed liquid was
-70 subjected to a purification step by chromatography to produce a corresponding liquid sugar stream. The hydrolyzed liquid stream was introduced into a chromatography column containing a resin (DIAION UBK 530) at a temperature of 50°C, a flow rate of 60 L/h, and a contact time of 0.5 BVH.
The sugar content of each hydrolyzed liquid stream is reported in the corresponding conversion experiment. The streams may include other compounds, which are not relevant to demonstrating the described conversion process and are therefore not reported in the table.
Example 1: Batch hydrogenation reaction
A 150 ml volume of flow 1 and 1.25 g of 2% Ru/C catalyst (Johnson Matthey Extrudate type 642, ground to a powder before use) were introduced into a 300 ml stainless steel batch reactor (Parr reactor). The reactor was closed, purged with nitrogen, and finally pressurized with hydrogen at a pressure of 20 bar with a temperature of 25°C. The reactor was heated to 85°C for 30 minutes, then held at 85°C for 30 minutes and
-71cooled to 25°C in 35 minutes. The reaction mixture was separated from the catalyst by filtration through a 0.22 μm PTFE filter and analyzed by HPLC. The compositions of the liquid sugar stream 1 and the hydrogenated mixture are shown in Table 3. _________________________________
<td></td><td>Composition of liquid sugar flow 1 (g/l)</td><td>Hydrogenated mixture (g/l)</td>
<td>Glucose</td><td> 1,39</td><td> 0,92</td>
<td>Arabinose</td><td> 1,11</td><td>nd</td>
<td>Xylose</td><td> 35,58</td><td> 8,52</td>
<td>Sorbitol</td><td>nd</td><td> 0,43</td>
<td>Arabitol</td><td>nd</td><td> 2,25</td>
<td>Xylitol</td><td>nd</td><td> 24,2</td>
Table 3. Composition of the liquid stream of sugar 1 and hydrogenated mixture of example 1.
Example 2: Batch hydrogenation reaction
A volume of 150 ml of flow 2 and an amount of 1.25 g of a 2% Ru/C catalyst (Johnson Matthey Extrudate type 642, ground to powder form before use), were introduced into a stainless steel batch reactor from
-72300 ml (Parr reactor). The reactor was closed, purged with nitrogen, and finally pressurized with hydrogen at 20 bar at a temperature of 25°C. The reactor was heated to 100°C for 30 minutes, then held at 100°C for 60 minutes, and cooled to 25°C in 35 minutes. The reaction mixture was separated from the catalyst by filtration through a 0.22 μm PTFE filter and analyzed by HPLC. The compositions of the liquid sugar stream 2 and the hydrogenated mixture are given in Table 4.
<td></td><td>Composition of liquid sugar flow 2 (g/l)</td><td>Hydrogenated mixture (g/l)</td>
<td>Glucose</td><td> 3,16</td><td>nd</td>
<td>Arabinose</td><td> 1,57</td><td>nd</td>
<td>Xylose</td><td> 48,8</td><td>nd</td>
<td>Sorbitol</td><td>nd</td><td> 2,04</td>
<td>Arabitol</td><td>nd</td><td> 4,16</td>
<td>Xylitol</td><td>nd</td><td> 40,6</td>
Table 4. Composition of the liquid stream of sugar 2 and hydrogenated mixture of example 2.
Example 3: Continuous hydrogenation reaction
A stainless steel tubular reactor
-73 (h 40 cm, di 2 cm) was filled with 2% Ru/C catalyst (Johnson Matthey Extrudate type 642) and glass beads. The catalyst bed consisted of a 4 cm top layer of glass beads (0 = 1.5 mm), a 25 cm catalyst layer (ground and screened extruded catalyst, 0.6 < 0 < 1.2 mm), and an 11 cm bottom layer of glass beads. The reactor was purged with nitrogen and pressurized with hydrogen at 60 bar at room temperature. The hydrogen flow was subsequently adjusted to 37 ml/min. The reactor was heated to 110°C for 40 min, and once the reaction temperature was reached, the liquid sugar 3 flow was continuously fed through an HPLC pump at 0.5 ml/min onto the catalyst bed, to achieve a liquid hourly space velocity of approximately 1.5 h.<sup>-1</sup>Samples of the reaction solution were continuously withdrawn from a collection tank and analyzed by HPLC. The compositions of the sugar liquid stream 3 and the hydrogenated mixture at 20 hours and 50 hours are shown in Table 5.
<td></td><td>Composition of the flow</td><td>Solution hydrogenated</td><td>Mixture hydrogenated</td>
<td></td><td>liquid of sugar 3 (g/l)</td><td>(g/l) after 20 hours on flow</td><td>(g/l) after 50 hours on the flow</td>
<td>Glucose</td><td> 1,75</td><td>nd</td><td>nd</td>
<td>Arabinose</td><td> 4,36</td><td>nd</td><td>nd</td>
<td>Xylose</td><td> 43,9</td><td>nd</td><td>nd</td>
<td>Sorbitol</td><td>nd</td><td> 1,62</td><td> 1,50</td>
<td>Arabitol</td><td>nd</td><td> 7,28</td><td> 6,62</td>
<td>Xylitol</td><td>nd</td><td> 38,9</td><td> 37,2</td>
Table 5. Compositions of the liquid stream of sugar 3 and hydrogenated mixture at 20 hours and 50 hours of Example 3.
Example 4: Continuous hydrogenolysis reaction of a hydrogenated mixture
A stainless steel tubular reactor (40 cm high, 2 cm wide) was filled with a nickel-based catalyst and glass beads. The catalyst bed consisted of a 4 cm top layer of glass beads (0 = 1.5 mm), a 25 cm catalyst layer (extruded, ground and screened catalyst, 0.6 < 0 < 1.2 mm), and an 11 cm bottom layer of glass beads.
The reactor was purged with nitrogen and pressurized with hydrogen to a pressure of 60 bar at
-75 room temperature. The hydrogen flow was then set to the desired reaction rate of 37 ml/minute. The reactor was then heated to 200°C for 90 minutes and, when the reaction temperature was reached, a solution obtained by hydrogenation of stream 3 (shown in example 3) was added, to which a quantity of 5.3 g/l of sodium hydroxide was added, and fed through an HPLC pump at 0.5 ml/min onto the catalyst bed, to have an hourly space velocity of the liquid of about 1.5 h.<sup>-1</sup>Samples of the reaction solution were continuously collected from a collection tank and analyzed by HPLC. The compositions of the hydrogenated stream 3 and the hydrogenlyzed mixture at 20 hours and 50 hours are shown in Table 6. The composition of the hydrogenated stream 3 was close to the compositions of the samples in Table 5.
<td></td><td>Feed composition (g/l)</td><td>Hydrogenated solution (g/l) after 20 hours on flow</td><td>Solution hydrogen lysate (g/l) after 50 hours on flow</td>
<td>Sorbitol</td><td> 1,37</td><td>nd</td><td>nd</td>
<td>Arabitol</td><td> 7, 71</td><td> 4,28</td><td> 4,68</td>
<td>Xylitol</td><td> 36,7</td><td> 6,85</td><td> 8,23</td>
<td>Ethylene glycol</td><td>nd</td><td> 7,94</td><td> 8,51</td>
<td>1,2-propylene glycol</td><td>nd</td><td> 7,37</td><td> 7,80</td>
<td>Glycerol</td><td>nd</td><td> 6,52</td><td> 6,76</td>
<td>Lactic acid</td><td>nd</td><td> 2,38</td><td> 2,55</td>
Table 6. Compositions of hydrogenated stream 3 and hydrogenolysate mixture at 20 hours and 50 hours of Example 4.
Examples 3 and 4 showed how, in a continuous manner, a stream can be treated first by hydrogenation and then by hydrogenolysis, effectively obtaining ethylene glycol and 1,2-propylene glycol.
Example 5: Continuous hydrogenolysis reaction of a synthesis solution
A stainless steel tubular reactor (40 cm high, 2 cm wide) was loaded with a nickel-based catalyst and glass beads. The catalyst bed consisted of a 4 cm top layer of glass beads (0 = 1.5 mm), a 25 cm catalyst layer (extruded catalyst) and a 10 cm catalyst layer (extruded catalyst).
-77ground and sifted, 0.6 < 0 < 1.2 mm) and a 11 cm bottom layer of glass beads.
In a first hydrogenolysis test (Test 1) the reactor was purged with nitrogen and pressurized with hydrogen at a pressure of 80 bar and a temperature of 25°C. The hydrogen flow was subsequently set at 150 ml/minute. The reactor was then heated to 210°C for 90 minutes and, when the reaction temperature was reached, an aqueous solution containing 25 wt% xylitol and 0.5 wt% sodium hydroxide was fed through an HPLC pump at 0.5 ml/min onto the catalyst bed, in order to have a liquid hourly space velocity of approximately 1.5 h.<sup>-1</sup>Samples of the polyol blends were continuously collected from a collection tank and analyzed by HPLC.
In a second hydrogenolysis test (Test 2), the reactor was purged with nitrogen and pressurized with hydrogen at a pressure of 60 bar and a temperature of 25°C. The hydrogen flow rate was subsequently set at 37 ml/minute. The reactor was then heated to 200°C for 90 minutes, and when the reaction temperature was reached, an aqueous solution containing
-78nently 5 wt% xylitol and 0.5 wt% sodium hydroxide through an HPLC pump at 0.5 ml/min, onto the catalyst bed, to have a liquid hourly space velocity of about 1.5 h<sup>-1</sup>Samples of the polyol blends were continuously collected from a collection tank and analyzed by HPLC.
The compositions of the polyol blends after 20 hours of flow and comparison with the hydrogenolysis performance of tests 1 and 2 are given in Table 7.
<td rowspan="3"></td><td>Test 1</td><td>Test 2</td>
<td>Xylitol 25% by weight, 210°C, 80 bar, LHSV 1.5 h<sup>-1</sup>, xylitol:NaOH (moles:moles) 12:1</td><td>Xylitol 5% by weight, 200°C, 60 bar, LHSV 1.5 h<sup>-1</sup>, xylitol:NaOH (moles:moles) 2:1</td>
<td colspan="2">Composition of polyol blends (g/l)</td>
<td>Xylitol</td><td> 28,2</td><td> 7,85</td>
<td>Ethylene glycol</td><td> 44,8</td><td> 9,22</td>
<td>1,2-propylene- glycol</td><td> 50,9</td><td> 8,05</td>
<td>Glycerol</td><td> 15,4</td><td> 6,22</td>
<td>Arabitol</td><td> 2,51</td><td> 3,67</td>
<td>Lactic acid</td><td> 8,26</td><td> 2,23</td>
<td></td><td colspan="2">Hydrogenation performance (wt%)</td>
<td>Surrender of conversion xylitol</td><td> 85,2</td><td> 83,7</td>
<td>Selectivity ethylene glycol</td><td> 27,5</td><td> 23,4</td>
<td>Selectivity 1,2-propylene glycol</td><td> 31,3</td><td> 20,4</td>
<td>Selectivity glycerol</td><td> 9,44</td><td> 15,6</td>
<td>Selectivity arabitol</td><td> 1,54</td><td> 8,56</td>
<td>Selectivity lactic acid</td><td> 5,07</td><td> 4,98</td>
Table 7. Compositions of polyol blends and hydrogenolysis performances of tests 1 and 2.
Example 6: Aqueous reforming of high-boiling polyols
In the paper “Production of hydrogen by aqueous-phase reforming of glycerol” by Z. Tian et al. (International Journal of Hydrogen Energy 33 (2008) 6657-6666), several examples of conversion of glycerol to hydrogen by the APR process are reported.
Specifically, the experiments were performed in a tubular reactor (58 cm high, 3 cm wide) containing a volume of 5 ml of the chosen catalyst. The reaction was carried out at 230°C, 32 bar, and a LHSV of 8.4 h.<sup>-1</sup>, using a 10% solution
-81wt glycerol as starting product.
First, various metal-based catalysts supported on alumina were tested. The catalysts were prepared by incipient moisture impregnation, starting from water-soluble precursor salts. As shown in Table 8, the best results were obtained with the Pt/Al2O3 catalyst, considering the glycerol-to-gas conversion product and the hydrogen produced in the gas phase. ____________________________________________
<td>Catalyst</td><td>Conversion carbon a gas (%)</td><td>Quantity H<sub>2</sub> in the gaseous phase (moles%)</td><td>Yield H<sub>2</sub> (μmoles · min<sup>-1</sup> · g<sub>2</sub>AT<sup>-1</sup>)</td>
<td>Pt/Al<sub>2</sub>OR<sub>3</sub></td><td> 18, 9</td><td> 69,7</td><td> 572,2</td>
<td>Ni/Al<sub>2</sub>OR<sub>3</sub></td><td> 15, 8</td><td> 59, 0</td><td> 167,7</td>
<td>Co/Al<sub>2</sub>OR<sub>3</sub></td><td> 21,0</td><td> 40, 9</td><td> 102,2</td>
<td>Cu/Al<sub>2</sub>OR<sub>3</sub></td><td> 2,0</td><td> 94,5</td><td> 409, 8</td>
Table 8. Comparison of various metal catalysts supported in the APR of a glycerol solution.
Once the most active phase was defined, the influence of the catalyst support was examined. Various supported platinum catalysts were prepared and compared.
<td>Catalyst</td><td>Conversion of carbon to gas (%)</td><td>Quantity H<sub>2</sub> in the gaseous phase (moles%)</td><td>Yield H<sub>2</sub> (μmoles · min<sup>-1</sup> · gCAT<sup>-1</sup>)</td>
<td>Pt/Al<sub>2</sub>OR<sub>3</sub></td><td> 18, 9</td><td> 69, 8</td><td> 572,2</td>
<td>Pt/SiO2</td><td> 10,8</td><td> 71,8</td><td> 369,4</td>
<td>Pt/AC</td><td> 17,2</td><td> 69, 6</td><td> 307,7</td>
<td>Pt/MgO</td><td> 13, 8</td><td> 79,9</td><td> 431, 9</td>
<td>Pt/HUSY</td><td> 22,0</td><td> 71,8</td><td> 337,0</td>
<td>Pt/SAPO-11</td><td> 13,3</td><td> 72,8</td><td> 222,1</td>
Table 9. Comparison of various platinum catalysts supported in the APR of a glycerol solution.
As seen in Table 6, alumina appears to be the best performing support for the platinum catalyst in the glycerol APR.
Hydrogen reaction equilibria
The general reactions involved in the conversion of the xylose stream to the polyol mixture are as follows:
hydrogenation:
C5H10O5 (xylose) + H2 ^ C<sub>5</sub>Hi<sub>2</sub>O5 (xylitol) (Reaction 1)
Hydrogenolysis:
C<sub>5</sub>H<sub>12</sub>OR<sub>5</sub> (xylitol) + 2 H<sub>2</sub> ^ C<sub>2</sub>H<sub>6</sub>OR<sub>2</sub> (ethyl-83-hexylglycol) + C3H8O2 (1,2-propylene glycol) + H<sub>2</sub>O (Reaction 2)
C<sub>5</sub>H<sub>12</sub>OR<sub>5</sub> (xylitol) + H<sub>2</sub> ^ C<sub>2</sub>H<sub>6</sub>OR<sub>2</sub> (ethylene glycol) + C<sub>3</sub>H<sub>8</sub>OR<sub>3</sub> (glycerol) (Reaction 3)
C<sub>5</sub>H<sub>12</sub>OR<sub>5</sub> ^ C<sub>2</sub>H<sub>6</sub>OR<sub>2</sub> (ethylene glycol) + C<sub>3</sub>H6O<sub>3</sub> (lactic acid) (Reaction 4)
C<sub>5</sub>H<sub>12</sub>OR<sub>5</sub> (xylitol) ^ C<sub>5</sub>H<sub>12</sub>OR<sub>5</sub> (arabitol) (Reaction 5)
The previous hydrogenolysis reactions occur simultaneously.
1. General hydrogen equilibrium of example 5
Considering that only reactions 1 to 3 consume hydrogen, the respective overall hydrogen consumption in the production of the polyol mixture is summarized in Table 10.
<td></td><td colspan="2">H Piers<sub>2</sub> consumed</td>
<td></td><td>Test 1</td><td>Test 2</td>
<td>Reaction 1</td><td> 1,67</td><td> 0,33</td>
<td>Reaction 2</td><td> 1,34</td><td> 0,21</td>
<td>Reaction 3</td><td> 0,17</td><td> 0,07</td>
<td>Total</td><td> 3,18</td><td> 0,61</td>
Table 10. Total hydrogen consumption of e-84 example 4
The high-boiling compounds that make up the polyol blend are xylitol, arabitol, glycerol, and lactic acid. The high-boiling compounds can be treated by aqueous reforming (APR) to produce hydrogen.
The APR reactions of the 4 compounds are:
C5H12O5 (xylitol) + 5 H2O ^ 5 CO2 + 11 H2 (Reforming reaction 1)
C5H12O5 (arabitol) + 5 H2O ^ 5 CO2 + 11 H2 (Reforming reaction 2)
C3H8O3 (glycerol) + 3 H2O ^ 3 CO2 + 7 H2 (Reforming reaction 3)
C3H6O3 (lactic acid) + 3 H2O ^ 3 CO2 + 6 H2 (Reforming reaction 4)
The respective general quantities of hydrogen that can be obtained by APR are given in Table 11.
<td></td><td colspan="2">H Piers<sub>2</sub> produced</td>
<td></td><td>Test 1</td><td>Test 2</td>
<td>Reforming reaction 1</td><td> 2,04</td><td> 0,57</td>
<td>Reforming reaction 2</td><td> 0,18</td><td> 0,47</td>
<td>Reforming reaction 3</td><td> 1,17</td><td> 0,26</td>
<td>Reforming reaction 4</td><td> 0,55</td><td> 0,15</td>
<td>Total</td><td> 3,94</td><td> 1,45</td>
Table 11. Amount of hydrogen from reforming
-85 of the high-boiling compounds of test 1 of example 4.
Thus, the amount of hydrogen that can be generated by aqueous reforming of the high-boiling compounds present in the polyol mixture is greater than the amount of hydrogen required for the conversion of the xylose solution to the polyol mixture.
Contents5
Every citation, both waysCites: the store holds 7 of 8
| Document | Relation | Office | Category | Cited during | Relevant claims |
|---|---|---|---|---|---|
| US2011160482A1 | Cites | United States of America | A | Search report | 1-34 |
| US2011160482A1 | Cites | United States of America | A | Search report | 1-34 |
| US2011319672A1 | Cites | United States of America | A | Search report | 1-34 |
| US2011319672A1 | Cites | United States of America | A | Search report | 1-34 |
| US6964757B2 | Cites | United States of America | A | Search report | 1-34 |
| US6964757B2 | Cites | United States of America | A | Search report | 1-34 |
| US8198486B2 | Cites | United States of America | AD | Search report | 1-34 |
| HM BAUDEL ET AL: "Xylitol production via catalytic hydrogenation of sugarcane bagasse dissolving pulp liquid effluents over Ru/C catalyst", JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, vol. 80, no. 2, 1 February 2005 (2005-02-01), pages 230 - 233, XP055126369, ISSN: 0268-2575, DOI: 10.1002/jctb.1155 | Non-patent | – | – | Search report | – |
| JIYING SUN ET AL: "Selective hydrogenolysis of biomass-derived xylitol to ethylene glycol and propylene glycol on supported Ru catalysts", GREEN CHEMISTRY, vol. 13, no. 1, 1 December 2010 (2010-12-01), pages 135 - 142, XP055089872, ISSN: 1463-9262, DOI: 10.1039/c0gc00571a | Non-patent | – | – | Search report | – |
| WEN G ET AL: "Production of hydrogen by aqueous-phase reforming of glycerol", INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, ELSEVIER SCIENCE PUBLISHERS B.V., BARKING, GB, vol. 33, no. 22, 1 November 2008 (2008-11-01), pages 6657 - 6666, XP025627075, ISSN: 0360-3199, [retrieved on 20081011], DOI: 10.1016/J.IJHYDENE.2008.07.072 | Non-patent | – | – | Search report | – |
8 members in 6 offices
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| TO20130833 | Italy | A | |
| IT2013TO00833 | – | – | – |
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| Document | Office | Kind | |
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| ITTO20130833A1This record | Italy | A1 | |
| WO2015055315A1 | World Intellectual Property Organization (WIPO) | A1 | |
| TW201522292A | Taiwan Province of China | A | |
| WO2015055315A9 | World Intellectual Property Organization (WIPO) | A9 | |
| IT1420306B1 | Italy | B1 | |
| CN105658571A | China | A | |
| EP3057907A1 | European Patent Office (EPO) | A1 | |
| US2016244555A1 | United States of America | A1 |
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Titles2
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- PROCEDIMENTO PER LA PRODUZIONE DI POLIOLI
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- PROCEDURE FOR THE PRODUCTION OF POLYOLS
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- CPC, 17
- C01B3/323
- C08G63/183
- C07C29/132
- C07C29/60
- C07C29/00
- C01B2203/0233
- C01B2203/065
- C01B2203/1217
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- C01B2203/06
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