Catalyst supported on carbon having macroporosity for purification of aromatic acids

ES 2 275 014 T3

DESCRIPTION

Macroporosity carbon supported catalyst for purifying aromatic acids.

Field of the invention

The present invention relates generally to catalyst composites containing extruded catalyst supports and processes for making and using the catalyst composites. In particular, the present invention relates to catalyst materials and processes associated with the purification of terephthalic acid.

Background of the invention

Catalytic processes are indispensable in the chemical industry. Catalyst processes often employ a catalyst that is incorporated into a support. The effective use of the catalyst often corresponds to the quality of the catalyst support. Poor quality of catalyst supports, due to at least one of the following physical degradation, chemical degradation, undesired properties, and inconsistent properties, limits the effectiveness of the catalysts incorporated into them. Conditions such as elevated temperatures, elevated pressures, and high or low pH environments pose challenges to the integrity of the catalyst supports.

For example, conventional catalyst compounds for purification of terephthalic acid via Amoco's medium container process (PTA catalysts) are comprised of palladium support on granular 4 x 8 carbon mesh. These catalyst compounds are designed to remove the two main impurities present in crude terephthalic acid; namely the yellow color and 4-carboxy benzaldehyde (4-CBA).

Carbon is the preferred support material for conventional PTA catalysts, as it is essentially the only readily available material that can simultaneously give an effective catalyst for color removal, 4-carboxy-benzaldehyde removal, and also support the extremely corrosive environment of the terephthalic acid purification process. Although conventional carbon supported PTA catalysts have been widely used over the past 20 years, such catalyst compounds suffer from several disadvantages. These disadvantages include: highly irregular shapes that result in possible maldistribution of liquid or gas flows in a catalyst reactor bed using such catalyst compounds; irregular shapes that have sharp, brittle edges and corners that tend to break off and contaminate the PTA product with dust and unwanted black particles; brittleness that also leads to breakage and the appearance of black dust / particles that contaminate the PTA product; natural origin, that is to say coconut shell that carries non-uniform shapes and, consequently, the lack of consistency of the carbon support; and, since they are generally derived from walnut shell, such activated carbon is highly microporous, leading to the requirement to locate all active catalyst metal on the surface of the particles, where it is undesirably susceptible to loss during movement and to abrasion that occurs during transportation and handling.

Particularly problematic is the unpredictable and uncontrollable mix of irregular shapes and sizes associated with commonly used granular coconut carbon backings. The granular coconut carbons are also, for the most part, microporous; that is, they have numerous pores that have a pore diameter of less than 50 A. as a result, the catalyst metals must be located near the outer edges of the supports to avoid low activity due to mass transfer resistances. However, when the catalyst metals are located near the outer edges of the supports, they are subject to losses due to mechanical wear and therefore the catalyst support loses its activity. The catalyst metals located near the outer edges of a support are easily accessible to the corrosion metals that are usually present in the reactor feeders and, therefore, are subject to their deactivation.

In an attempt to overcome the disadvantages associated with conventional carbon supported catalysts, non-carbon catalyst supports are used in catalyst processes. Non-carbon supports include alumina supports, silica supports, alumina-silica supports, various clays supports, titanium and zirconium supports. However, there are at least one of two disadvantages associated with non-carbon catalyst supports; that is, they can weaken and lose physical strength, they can dissolve in highly corrosive media (such as hot aqueous solutions of terephthalic acid), and they present difficulties in removing the undesirable color of crude terephthalic acid.

EP-A-1 127 865 describes the use of a granular activated carbon in the preparation of a catalyst composition for use in the hydrogenation of halogenated trifluoroacetone to produce trifluoroacetone.

EP-A-0 347 830 describes the use of molded activated carbon made from coconut shell in a catalytic hydrogenation reaction to produce trifluoroethylene.

US-A-5,877,360 describes the use of an extruded active carbon in the hydrogenation of chlorodifluoromethane.

ES 2 275 014 T3

Therefore, better catalyst supports and catalyst compounds are desired. Specifically, improved PTA catalyst supports and PTA catalyst compounds are desired to provide improved processes for purifying terephthalic acid and improved pot lives.

Summary of the invention

The present invention is designed to address at least one, and preferably all, of the above advantages by providing a catalyst compound containing a composite support that is formed into mesoporous and macroporosity forms. The catalyst compounds of the present invention enjoy a long useful life compared to conventional catalyst compounds, since they contain a support composed of an extruded and heat-treated material capable of withstanding harsh environments and corrosive reactions, such as those that occur. found in catalyzing the PTA. In this regard, the catalyst compounds of the present invention possess a lower deactivation index than conventional catalyst compounds. The catalyst compounds of the present invention also enjoy equal or better activity, with about 30% to about 50% by weight of a less active metal compared to conventional catalyst compounds.

One aspect of the invention relates to a composite catalyst containing a precious metal catalyst and an extruded catalyst support containing an extruded and heat-treated activated carbonaceous material possessing a specifically defined pore structure, with a first series of pores. having a pore diameter of at least 4 x 10 ⁹ m (40 A) and at most 1 x 10 ⁸ m (100 A), with a porosity of at least about 0.15 cc / g, and a second series of pores having a pore diameter of at least 5 x 10 ⁷ m (5,000 A) and at most 2 x 10 ⁶ m (20,000 A) with a porosity of at least about 0.3 cc / g, where at least 38% of the total Hg porosity occurs in pores having a diameter of 1 x 10^-7 m (1,000 A) and greater. Preferably, the extruded activated carbonaceous material may possess pores in which at least 40% of the total Hg porosity occurs in pores having a diameter of 2 x 10² m (200 .A) or greater.

Another aspect of the invention relates to a process for making a catalyst compound that involves mixing at least one carbonaceous material and a liquid to form a mixture; extruding the mixture into a shaped material; optionally drying the shaped material; heat treating the shaped material at a temperature of 600 ° C to 1,500 ° C to provide a catalyst support, wherein the catalyst support possesses a first series of pores having a pore diameter of at least 4 x 10^-9 m (40 A) and at most 1 x 10 ⁸ m (100 A) with a porosity of at least about 0.15 cc / g, and a second series of pores having a pore diameter of at least 5 x 10^-6 m (5,000 A) and at most 2 x 10 ⁶ m (20,000 A) with a porosity of at least about 0.3 cc / g, where at least 38% of the total Hg porosity occurs in pores having a diameter of 1 x 10 ⁷m (1,000 A) and greater, and contacting a precious metal catalyst with the catalyst support.

Yet another aspect of the invention relates to a process of purifying a crude polycarboxylic aromatic acid composition that involves contacting the polycarboxylic aromatic acid composition with the present composite catalyst. And yet another aspect of the invention relates to a process of purifying a crude amine composition or a crude alkynyl amine composition which involves contacting the crude amine composition or the crude alkynyl amine composition with the present composite catalyst.

Brief summary of the figures

Figure 1 shows a graph of the pore diameter distribution of various conventional granular carbons and various embodiments of extruded carbon in accordance with one aspect of the present invention.

Figure 2 shows a graph of the pore diameter distribution of conventional granular carbon and extruded carbon in accordance with one aspect of the present invention.

In each of Figures 1 and 2, the pore diameter is recorded in angstrom, where 1 angstrom corresponds to 1x10^-10 m.

Detailed description of the invention

In one embodiment, the present invention involves the preparation of catalyst compounds containing an extruded carbon catalyst support. The extruded catalyst support is particularly suitable for metallic catalysts, especially palladium or platinum. The process according to the present invention of preparing the extruded catalyst support may involve mixing a carbonaceous material and optional additives. Preferably a liquid is added to the mixture to give a stiff mass which is then extruded, optionally dried and heat treated to provide a material as set forth in claim 7. After heat treatment of the extrudate, and optionally drying, impregnation with an active metal catalyst is carried out. In another embodiment, the present invention involves the use of composite catalyst in a catalyst process, such as in the purification of crude terephthalic acid.

The extruded carbon catalyst support contains a carbonaceous material, and optionally one or more additives. The carbonaceous material can be derived from any suitable carbon source. The carbonaceous material used initially is an activated carbon or a non-activated carbon that can be converted to an activated carbon at some point.

ES 2 275 014 T3 moment during the formation of the extruded carbon catalyst support. For example, charcoal (an unactivated carbonaceous material) can be converted to activated carbon during the heat treatment step (described later). Carbonaceous materials include activated carbon derived from coal, lignite, wood, walnut shells, peat, tars, cokes, and the like; and an unactivated carbon derived from charcoal residue powder (eg, charcoal).

The carbonaceous material combined with any optional additives is normally in powder form. In one embodiment, the carbonaceous material has a particle size (mean particle size) of less than about 100 microns. In another embodiment, the carbonaceous material has a particle size of less than about 80 microns. In yet another embodiment, the carbonaceous material has a particle size of less than about 50 microns. In yet another embodiment, the carbonaceous material has a particle size of less than about 25 microns.

Carbonaceous materials are commercially available or can be made. For example, carbonaceous materials can be derived from coal, coke, coal coke, petroleum coke, lignite, polymeric materials, graphite, bone, wood, walnut shells including coconut shells, resin residues, lignocellulosic materials, including pulp. and paper, fruit pits, fruit pips, and sugar. The source of carbonaceous materials is not crucial in the present invention. Consequently, another advantage associated with the present invention is that the source of carbonaceous materials is not crucial. US Patents 3,084,394, 3,109,712, 3,171,720, 3,198,714, 3,310,611, 3,387,940, 3,342,555, 3,345,440,3,352,788, 3,446,593,3,565,980 , 3,574,548,3,626,042, 3,628,984,3,634,569, 3,635,676,3,663. 171, 3,859,421, 4,029,567, 4,082,694, 4,206,078, 4,263,268, 4,329,260, 4,603,119, 4,668,496, 4,954,469, 4,987,116, describe various carbonaceous materials.

Carbonaceous materials are either chemically activated or not chemically activated. Chemical activating agents include one or more of the alkali metal hydroxides, alkali metal carbonates, alkali metal sulfide, alkali metal sulfates, alkaline earth metal carbonates, alkaline earth metal chlorides, alkaline earth metal sulfates, phosphates of alkaline earth metals, phosphoric acid, polyphosphoric acid, pyrophosphoric acid, zinc, chloride, sulfuric acid, and the like. Chemical activation is performed by contacting one or more carbonaceous materials with one or more chemical activating agents, mixing, optionally heating, optionally washing / rinsing, and optionally drying the chemically activated material.

In one embodiment, the extruded carbon catalyst support contains about 50% by weight or more and about 100% by weight or less of at least one carbonaceous material. In another embodiment, the extruded carbon catalyst support contains about 60% by weight or more and about 99.9% by weight or less of at least one carbonaceous material. In yet another embodiment, the extruded carbon catalyst support contains about 70% by weight or more and about 99% by weight or less of at least one carbonaceous material. In yet another embodiment, the extruded carbon catalyst support contains about 75% by weight or more and about 95% by weight or less of at least one carbonaceous material.

Extruded carbon catalyst supports are commercially available. For example, extruded carbon materials are available from Ceca, Norit, Westvaco, and Takeda. Alternatively, the extruded carbon catalyst support can be made by mixing the carbonaceous material and any optional additives, forming the mixture into a molded material, optionally drying the molded material, and heat treating the molded material to provide the hard. the extruded carbon catalyst support. When mixing the carbonaceous material and any optional additives, it is preferable to add water (and / or other liquid solvent). Tap water or deionized water can be used, although deionized water is preferred. Water is added to facilitate mixing and subsequent formation (eg, extrusion), and therefore is added in any suitable amount to facilitate mixing and subsequent formation. Since the water is ultimately removed in the later stages of drying and heat treatment, the amount of water added is not crucial to the present invention.

However, in one embodiment, the mixture of optional additives and carbonaceous material typically contains from about 5% to about 80% by weight of water. In another embodiment, the mixture of optional additives and carbonaceous material contains from about 10% to about 70% by weight of water. In another embodiment, the mixture of optional additives and carbonaceous material contains from about 20% to about 60% by weight of water.

Additives include any material that facilitates mixing and subsequent formation. Additives include rheology control agents, extrusion aids, suspending agents, surfactants, low-boiling organic compounds, rosin materials, polymeric additives, dispersing agents such as ammonium lignosulfonates and metal nitrates, sulfates, carbonates. , phosphates, hydroxides and oxides. Rheology control agents include cellulose ethers, polyvinyl alcohols, and polyalkylene oxides. Examples of cellulose ethers include sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), methyl cellulose (MC), and derivatives thereof. A commercially available cellulose ether is Methocel. Methocel, which contains water and hydroxypropyl methylcellulose ether polymer, possesses a high thermal gelatin point, such as the products designated K4M and K15m available from the Dow Chemical Company. Preferred polyalkylene oxides include polyethylene oxides. Extrusion aids include glycol compounds, such as polyalkylene glycols. In a specific embodiment, polyethylene glycol, such as PEG 400 available from Union Carbide, can be

ES 2 275 014 T3 add as extrusion aid. In general, the glycol compounds are dissolved in water and then added to the dry ingredients.

In one embodiment, the extruded carbon catalyst support typically contains from about 0.01% to about 10% by weight of at least one additive. In another embodiment, the extruded carbon catalyst support contains from about 0.1% to about 5% by weight of at least one additive.

The carbonaceous powder mixture and any optional ingredients can be well mixed in a high speed mixer with water and a rheology control agent, such as Methocel, until a fairly stiff mass is obtained. This mass can be extruded into any suitable shape, including cylinders, cubes, stars, triplobes, tetralobes, balls, spheres, through suitable mechanical means. In one embodiment, mixing is carried out in a high intensity environment, such as supplied by a Littleford mixer available from Littleford Day, Inc., Florence, KY. Mixing is carried out for a sufficient time to result in a uniform fine mixture. In another embodiment, during mixing, water is added to the mixture in an amount to give a rigid dough-like material suitable for extrusion.

In one embodiment, the mixture of carbonaceous material and optional additives is mixed in a high intensity mixer for about 5 minutes to about 100 minutes. In another embodiment, the mixture of carbonaceous material and optional additives is mixed in a high intensity mixer for about 10 minutes to about 60 minutes. In yet another embodiment, the mixture of carbonaceous material and optional additives is mixed in a high intensity mixer for about 15 minutes to about 40 minutes.

After mixing, the mixed material is extruded into a suitable shape. The shape corresponds substantially to the shape of the resulting catalyst support. In a preferred embodiment, the mixed material is continuously extruded in a wide range of diameters and shapes. Examples of the forming or extrusion machines include extrusion molding machines, single screw extruders, twin screw extruders, co-extruders, pin extruders, linear extruders, and monofilament extruders.

The extrudate is then optionally molded into any desired shape. Examples of forming machines include molding machines, tableting machines, compaction granulators, marumarizers, and pellet formers. The shape of the extrudate includes spheres, tablets, cylinders, stars, triplets, tetralobes, balls, granules, honeycombs, and cubes. The shapes, generally referred to as "particulates", can be of any suitable size. However, in a preferred embodiment, the sizes of the shapes are substantially uniform. In another preferred embodiment, the mixed material is extruded into cylindrical shapes with diameters from about 1.5mm to about 3.5mm.

The extrudate has its components (the carbonaceous material and any optional additives) mixed evenly within it. Optional additives and carbonaceous material uniformly mixed into the subsequent resulting catalyst support contribute to the advantageous properties of the resulting extruded catalyst support and the resulting composite catalyst containing the catalyst support.

After extruding the material into a desired shape, the extrudate is optionally dried to remove any remaining liquid (and usually to remove any remaining water). Drying is carried out in the at least one desiccator, under vacuum (reduced pressure) and / or at elevated temperature (cooking) for a period of time sufficient to remove any remaining liquid from the formed material. Drying of the extrudate contributes to the wear resistance properties of the resulting extruded carbon catalyst support.

The way in which the extrudate dries is not critical, but in many cases, the drying conditions depend primarily on at least one of the dimensions of the extrudate, the shape of the extrudate, and the way in which the extrudate extruded material holds. In one embodiment, the dried extrudate contains less than about 3% by weight of free moisture. In another embodiment, the dried extrudate contains less than about 1% by weight of free moisture. In another embodiment, the dried extrudate contains less than about 0.5% by weight of free moisture.

In one embodiment, drying involves at least one of maintaining an elevated temperature (greater than about 35 ° C) overnight, drying overnight, and under vacuum overnight. By employing elevated temperatures, in one embodiment the extrudate is heated from about 35 ° C to about 150 ° C for a time from about 5 seconds to about 6 hours. In another embodiment, the extrudate is heated from about 40 ° C to about 110 ° C for a time from about 30 seconds to about 30 minutes. In yet another embodiment, the extrudate is heated from about 50 ° C to about 90 ° C for a time from about 1 minute to about 20 minutes. In a preferred embodiment, the extrudate is subjected to an incremental drying process (two-stage drying process), with the initial drying temperature from about 40 ° C to about 95 ° C, and more preferably from about 60 ° C to about 85 ° C, and then heated to at least about 100 ° C, and more preferably at least about 110 ° C, to complete the drying procedure.

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After drying, the extracted material is heat treated. However, in one embodiment, the drying step can be incorporated into the heat treatment step by initiating the heat treatment at a relatively low temperature (low temperatures relative to heat treatment temperatures). The extruded and dried material is heat treated in any suitable way to provide a hard catalyst support and to provide a catalyst support containing a carbonaceous material possessing properties corresponding to those of activated carbon (especially in embodiments where carbonaceous material is not used).

Heat treatment involves heating the extrudate to a temperature of 600 ° C to 1,500 ° C. Preferably, the heat treatment involves heating the extrudate to a temperature of from about 700 ° C to about 1000 ° C. More preferably, the heat treatment involves heating the extrudate to a temperature of from about 800 ° C to about 900 ° C. It is observed that the temperature can vary within a range of temperatures. For example, the temperature can be suddenly increased or increased steadily for the duration of the heat treatment.

The length of time for which the extrudate is heated depends primarily on the temperature, the content of the atmosphere, the size of the extrudate, the related equipment, and the identity of the components (the specific type of carbonaceous material and the optional additives). In one embodiment, the heat treatment involves heating the extrudate from about 15 minutes to about 5 hours. In another embodiment, the heat treatment involves heating the extrudate from about 30 minutes to about 4 hours. Heat-up time refers to the amount of time the extrudate itself is at the specified temperature (and therefore does not include ramps or cooldowns).

In one embodiment, the atmosphere in which the heat treatment is carried out contains at least steam or water vapor. The atmosphere can further contain at least one of an inert gas, air, oxygen, and carbon dioxide. Inert gases include the noble gases and nitrogen. The noble gases include helium, neon, argon, krypton, and xenon. In another embodiment, the atmosphere in which the heat treatment is carried out contains at least one steam / steam and an inert gas. In this regard, in one embodiment, the atmosphere in which the heat treatment is carried out contains a substantially inert atmosphere, such as from about 50% to about 100% of at least one inert gas and from about 0% to less than about 50% of one or more of vapor, air, oxygen, and carbon dioxide. In a preferred embodiment, the heat treating atmosphere contains steam and nitrogen.

In a preferred embodiment, the heat treating atmosphere contains from about 5% to about 100% steam and from about 0% to about 95% of at least one of an inert gas, air, oxygen, and carbon dioxide. In another embodiment, the heat treating atmosphere contains from about 20% to about 95% steam and from about 5% to about 80% of at least one of an inert gas, air, oxygen, and dioxide. carbon. In yet another embodiment, the heat treating atmosphere contains from about 30% to about 90% steam and from about 10% to about 70% of at least one of an inert gas, air, oxygen, and carbon dioxide.

After heat treatment, the optionally dried extrudate is cooled in any suitable way. In one embodiment, the optionally dried extrudate is cooled in an atmosphere containing an inert gas.

The extruded carbon catalyst supports resulting from the present invention possess a level of porosity that is controllable, primarily through varying the heat treatment parameters and by varying the relative amounts of the ingredients (carbonaceous material and optional additives). Porosity can also be controlled or can be further controlled by the amount and type of additive, such as rheology control agent or extrusion aid.

In one embodiment, the extruded carbon catalyst supports of the present invention have a bulk density of from about 400 grams per liter to about 1,000 grams per liter. In another embodiment, the extruded carbon catalyst supports of the present invention have a bulk density from about 425 grams per liter to about 750 grams per liter. In yet another embodiment, the extruded carbon catalyst supports have a bulk density of from about 440 grams per liter to about 600 grams per liter.

In general, the surface area of ​​the extruded carbon catalyst supports of the present invention correspond to a weighted average of the surface area of ​​the optional additives and carbonaceous material. In one embodiment, the surface area of ​​the extruded carbon catalyst supports is approximately 300 µm²/ g or more and approximately 1,600 m²/ g or less. In another embodiment, the surface area of ​​the extruded carbon catalyst supports is approximately 800 µm.²/ g or more and approximately 1,400 m²/ g or less.

In general, extruded carbon catalyst supports possess a unique pore size distribution that contributes to the advantages obtained by the present invention. While not wishing to be bound by theory, it is believed that the minimum surface area and / or pore size distribution in extruded carbon catalyst supports contribute to better aging (by maximizing the porosity of pore sizes of about

ES 2 275 014 T3 x 10 ⁸ m (200 A) or greater, such as at least 40% porosity at pore sizes of about 2x10^-8 m (200 A) or greater or at least 38% porosity at pore sizes of about 1x10 ⁷ m (1,000 A) or greater); better HMBA / toluic acid ratios; better removal of CBA and / or better removal of yellow color.

The extruded and heat-treated carbon catalyst possesses a pore size distribution in which a first set of pores containing a porosity of at least about 0.15 cc / g has a pore diameter of at least 4x10^-9 m (40 A) and at most 1x10 ⁸ m (100 A), and a second set of pores containing a porosity of at least about 0.3 cc / g has a pore diameter of at least 5x10 ⁷ m (5,000 A) and at most 2x10^-6 m (20,000 A) (Hg intrusion porosimetry, such as using a model Micrometrics Autopore-II 9220 porosimeter according to the analysis procedure outlined in one or more of US Patents 5,186,746; 5,316 .576 and 5,591,256). Preferably, the extruded carbon catalyst has a pore size distribution in which a first set of pores containing a porosity of at least about 0.2 cc / g has a pore diameter of at least 4x10⁹ m (40 A) and at most 1x10 ⁸ m (100 A), and a second set of pores containing a porosity of at least about 0.4 cc / g has a pore diameter of at least 5x10^-7 m (5,000 A) and at most 2x10 ⁶ m (20,000 A).

Referring to Figure 2, the pore structure of a typical conventional granular coconut carbon (Pica G202X) is compared to an extruded carbon (Takeda S2X) in accordance with an embodiment of the present invention. The pore volume distribution of carbon extruded according to the present invention weighs much more in large pores, whereas conventional granular coconut carbon weighs in relatively small pores.

For this reason, conventional granular coconut carbon is called microporous, while extruded carbon according to the present invention can be called mesoporous or macroporous.

Referring to Figure 1, the pore structure of typical conventional granular coco four carbons is compared to five different embodiments of the extruded carbons in accordance with the present invention. In the chart, conventional granular coconut carbons include Granular TA-485E available from Pica, Granular G202X available from Pica, Granular 206CAT available from Barneby-Waterlink, and Granular NCA available from Pica. Extruded carbons include Extruded AC40 / 3 available from Mint, Extruded RX3 Extra available from Noria, Extruded S2X available from Takeda. The pore volume distribution of carbons extruded in accordance with the present invention weighs much more in larger pores, whereas conventional granular coconut carbon weighs in relatively small pores. For example, as can be seen in the graph, at least approximately 40% of the porosity_orof total Hg is produced in pores with a diameter of 2x10 ⁸ m (200 A) and larger, such as 1x10 ⁷ m (1,000 A) and greater.

In Table 1 below, the amount (wt%) of palladium in a composite catalyst and the corresponding removal rates of 4-CBA are indicated. The 4-CBA removal rate is the ratio of the first order 4-CBA removal rate for the subject composite catalyst divided by the first order 4-CBA removal rate for a conventional standard composite catalyst (composite catalyst that contains a Pica G202X bracket). The catalyst compounds according to the present invention (containing Takeda C2X or Ceca AC40 / 3 based compound) exhibit better removal rates of 4-CBA compared to a standard compound catalyst (compound catalyst containing a Pica G202X support) .

Catalyst support

TABLE 1% Pd Elimination rate of 4-CBA

Takeda C2X Takeda C2X Takeda C2X Mint AC40 / 3 Mint AC40 / 3 Pica G202X

<td> 0,5</td><td> 1,25</td>

<td> 0,35</td><td> 1,11</td>

<td> 0,25</td><td> 0,95</td>

<td> 0,5</td><td> 1,2</td>

<td> 0,35</td><td> 1,15</td>

<td> 0,5</td><td> 1,0</td>

In one embodiment, the extruded carbon catalyst has a pore size distribution in which at least about 40% of the total Hg porosity occurs in pores having a diameter of about 2x10^-8 m (200 ja) and greater (Hg intrusion porosimetry). In another embodiment, the extruded carbon catalyst has a pore size distribution in which at least about 3_or8% of the total Hg porosity is produced in pores having a diameter of approximately 1x10 ⁷ m (1,000 ja) and older. In yet another embodiment, the extruded carbon catalyst has a pore size distribution in which at least about 34% of the total Hg porosity occurs in pores having a diameter of about 5x10^-7 m (5000 ha) and older.

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In one embodiment, the extruded carbon catalyst has an HMBA / toluic acid ratio at the end of a cycle of at least about 2.5. The HMBA / toluic acid ratio at the end of a cycle is the ratio of 4-hydroxymethyl benzoic acid to toluic acid present at the end of a test purification reaction (in the feeder, the HMBA / toluic acid ratio is approximately 0.44) . In another embodiment, the extruded carbon catalyst has an HMBA / toluic acid ratio at the end of a cycle of at least about 2.75. In yet another embodiment, the extruded carbon catalyst has a HMBA / toluic acid ratio at the end of a cycle of at least about 3. In yet another embodiment, the extruded carbon catalyst has a HMBA / toluic acid ratio at the end of a cycle of at least about 3.25.

Generally, the extruded carbon catalysts of the present invention have a longer life compared to a conventional granular carbon catalyst. In other words, the extruded carbon catalysts of the present invention generally possess a lower deactivation index than conventional granular carbon catalysts. For example, in one embodiment, the extruded carbon catalyst of the present invention containing 0.5% by weight of the metal catalyst has a life of about 1.5 times or more, longer than a conventional granular carbon catalyst that it contains 0.5% by weight of the same metal catalyst. In another embodiment, the extruded carbon catalyst of the present invention containing 0.5% by weight of the metal catalyst has a life approximately 2 times or more, longer than a conventional granular carbon catalyst containing 0.5%. by weight of the same metal catalyst.

In another embodiment, the extruded carbon catalyst of the present invention has a deactivation index that is approximately 25% or more lower than the deactivation index of a similarly charged conventional granular carbon catalyst (same amount of the same catalyst metal). In yet another embodiment, the extruded carbon catalyst of the present invention has a deactivation rate that is about 50% or more lower than the deactivation rate of a similarly charged conventional granular carbon catalyst.

Since the extruded carbon catalysts of the present invention possess a lower deactivation index than similarly charged conventional granular carbon catalysts, the activities of the extruded carbon catalysts of the present invention are higher after various levels of aging in comparison. with conventional granular carbon catalysts. In one embodiment, the extruded carbon catalyst of the present invention possesses an activity that is at least about 1.5 times that of the similarly charged conventional granular carbon catalyst after 6 months, 12 months, or 18 months, or 18 months of aging.

The low metal loaded extruded carbon catalysts of the present invention can generally perform the same as or even better than a conventional high metal loaded granular carbon catalyst. For example, in one embodiment, the extruded carbon catalyst of the present invention containing 0.25% by weight of metal catalyst possesses an activity equal to or greater than that of the conventional granular carbon catalyst containing 0.5% by weight. weight of the same metallic catalyst. In another embodiment, the extruded carbon catalyst of the present invention containing 0.35% by weight of metal catalyst has an activity equal to or greater than that of the conventional granular carbon catalyst containing 0.5% by weight thereof. metallic catalyst.

In one embodiment, the present invention involves forming a composite catalyst by impregnating the extruded carbon catalyst support with a solution of at least one catalytically active metal. The impregnation is effected by treating the extruded carbon catalyst support with an aqueous or organic solution of the desired metal or a combination of metals in an amount sufficient to deposit at least one catalytically active metal on or near the surface of the support, thereby providing a composite catalyst.

Typically, catalytically active metals include precious metals. Examples of catalytically active metals and metal blends include platinum, platinum and rhenium, platinum and ruthenium, platinum and tungsten, platinum and nickel, platinum and tin, platinum and iron, platinum and copper, platinum and rhodium, platinum and lead , platinum and germanium, platinum and gold, platinum and tellurium, palladium and gold, palladium and indium, palladium and sulfur, palladium and tellurium, palladium, palladium and rhenium, palladium and rhodium, palladium and tungsten, palladium and nickel, palladium and tin , palladium and copper, palladium and ruthenium, palladium and lead, palladium and germanium, cobalt, rhodium, ruthenium, osmium, iridium, various combinations thereof, etc. It should be understood that the above-mentioned list of catalytically active metals is only representative and therefore does not limit the type of metals that can be impregnated on the surface of the catalyst support.

The catalyst can be impregnated on / into the extruded carbon catalyst support in any suitable way. For example, immersion techniques, spraying techniques, and early humidification techniques can be employed. In one embodiment, the amount of catalyst in the composite catalyst is from about 0.01% to about 30% by weight. In another embodiment, the amount of catalyst in the composite catalyst is from about 0.1% to about 10% by weight. In yet another embodiment, the amount of catalyst in the composite catalyst is from about 0.2% to about 5% by weight. In one embodiment, the amount of extruded carbon catalyst support in the composite catalyst is from about 70% to about 99.9% by weight. In another embodiment, the amount of extruded carbon catalyst support in the composite catalyst is from about 90% to about 99.9%.

ES 2 275 014 T3 by weight. In another embodiment, the amount of extruded carbon catalyst support in the composite catalyst is from about 90% to about 99.9% by weight. In yet another embodiment, the amount of extruded carbon catalyst support in the composite catalyst is from about 95% to about 99.8% by weight.

The extruded carbon catalyst supports and catalyst compounds of the present invention are suitable for use in catalytic processes. Catalytic processes in which the extruded carbon catalyst supports and catalyst compounds of the present invention can be employed include hydrogenation, rearrangement, purification, dehydration, dehydrogenation, oxidation, reduction, polymerization, dehydrocyclization, reforming, hydrocracking, and isomerization. Specific catalytic reactions / procedures are too numerous to list, but the following are specific examples.

The extruded composite catalyst of the present invention is suitable for use in the purification of crude or relatively impure polycarboxylic aromatic acids, in particular crude terephthalic acid, isophthalic acid, phthalic acid and naphthalene dicarboxylic acid. The extruded composite catalyst of the present invention is also suitable for use in the purification of amines and alkynyl amines, and particularly aromatic amines, aromatic alkynyl amines, aliphatic amines and aliphatic alkynyl amines.

In one embodiment, the impure polycarboxylic aromatic acid is a crude product of the catalytic oxidation of an aromatic compound. Examples of suitable aromatic compounds include 1,2-dimethylnaphthalene; 2,6-dialkylnaphthalene; 2-acyl-6-alkylnaphthalene; 2,6-dimethylnaphthalene; 2,6-diethylnaphthalene; 2,6-diisopropylnaphthalene; 2acetyl-6-methylnaphthalene; 2-methyl-6-ethylnaphthalene; para-dialkylxylene; meta-dialkylxylene; and ortho-dialkylxylene; where the alkyl groups contain from 1 to about 6 carbon atoms. In a preferred embodiment, the purified crude acid according to the present invention is at least one of terephthalic acid formed by the oxidation of para-xylene, isophthalic acid formed by the oxidation of meta-xylene and 2,6-naphthalene acid. dicarboxylic formed by the oxidation of 2,6-dialkylnaphthalene (preferably 2,6-dimethylnaphthalene). In another embodiment, the crude polycarboxylic aromatic acid, such as 2,6-naphthalene dicarboxylic acid, is prepared by esterification, to form the corresponding ester, in this case dimethyl naphthalene dicarboxylate, and then hydrolyzing to form the acid. polycarboxylic aromatic which is then purified in accordance with the present invention.

Procedures for catalytically purifying crude polycarboxylic aromatic acids, including terephthalic acid, are known. For example, US Patents 3,607,921, 3,887,613, 3,919,306, 4,260,817, 4,281,179, 4,317,923,4,394,299,4,415,479,4,447,646,4,605,763, 4,629,715,4,791,226.4,803,295; 4,808,751, 4,892,972; 4,937. 378; 5,180,849; 5,362,908; 5,420,344; 5,616,792; 5,723,659; 5,756,833 describe various processes of catalytically purifying crude polycarboxylic aromatic acids and, in particular, terephthalic acid. Procedures for catalytically purifying crude amines and alkynyl amines, and in particular aromatic amines and aromatic alkynyl amines, are known. In this regard, the composite catalyst according to the present invention can be used in such processes.

In one embodiment, the composite catalyst is contacted with a relatively crude or crude terephthalic acid or aqueous solution that includes large amounts of impurities such as 4-carboxy benzaldehyde and undesirable coloration. Typically such impurities are present in amounts up to about 10,000 parts per million parts of terephthalic acid, by weight (although higher amounts are found in some cases). These impurities adversely affect subsequent polymerization reactions of terephthalic acid to produce polyethylene terephthalate, as well as undesirable coloration of the resulting polyethylene terephthalate polymers.

In this embodiment, the composite catalyst is contacted with an aqueous solution of relatively impure or crude terephthalic acid at an elevated temperature and pressure in a fixed catalyst bed. The crude terephthalic acid to be purified is dissolved in water or a similar polar solvent. Water is a preferred solvent; however, other suitable polar solvents include the lower molecular weight alkyl carboxylic acids, alone or in admixture with water.

In one embodiment, the temperature during catalytic purification is from about 100 ° C to about 350 ° C. In another embodiment, the temperature during catalytic purification is from about 225 ° C to about 340 ° C.

The pressure depends mainly on the temperature at which the purification procedure is carried out. Considering that the temperatures at which practical amounts of impure terephthalic acid can be dissolved are substantially higher than the normal boiling point of the polar solvent, the pressures are necessarily considerably above atmospheric pressure to keep the aqueous solution in the liquid phase. If the reactor is hydraulically full, the reactor pressure can be controlled by the pumping rate of the feeder. In one embodiment, the pressure during hydrogenation is about 1.034x10⁶ Pa (150 pounds per square inch, psig) at approximately 11.03x10⁶ Pa (1600 psig). In another embodiment, the pressure during hydrogenation is about 6,200x10⁶ Pa (900 psig) at approximately 8,274x10⁶ Pa (1200 psig).

ES 2 275 014 T3

In the operating mode where the process control is effected by adjusting the hydrogen partial pressure, the hydrogen partial pressure in the reactor is preferably about 6.895 x10⁴ Pa (10 psig) at approximately 5.576 x10⁶ Pa (800 psig), approximately 5,875 x10⁶ Pa (100 psig) at approximately 4,137 x10⁶ Pa (600 psig) or higher, depending on the power of the reactor pressure rating, the degree of contamination of the impure terephthalic acid, the activity and age of the particular catalyst used, and similar processing considerations. When purifying crude or crude terephthalic acid, in one embodiment, the reactor atmosphere contains from about 10% to about 40% by weight of hydrogen and from about 60% to about 90% by weight of water vapor. In another embodiment, when purifying crude or impure terephthalic acid, in one embodiment, the reactor atmosphere contains from about 15% to about 35% by weight of hydrogen and from about 65% to about 85% by weight of vapor. of water.

In the operating mode where the process control is effected by direct adjustment of the concentration in the feed solution, the latter is usually less than saturated in relation to hydrogen and the reactor itself is hydraulically full. Thus, an adjustment of the hydrogen flow rate to the reactor will result in the desired control of the hydrogen concentration in the solution. In general, an amount of hydrogen is supplied to the purification reactor which is sufficient to effect the desired hydrogenation under the reaction conditions employed.

In one embodiment, the activity indices for the removal of 4-carboxy benzaldehyde with 0.5% by weight of Pd catalyst compounds (made from Pd on the extracted carbon catalyst supports) of the present invention are about 1 h ¹ at about 2.6 h ¹. In another embodiment, the activity indices for removal of 4-carboxy benzaldehyde with 0.5% by weight of Pd catalyst compounds (made from Pd on the extracted carbon catalyst supports) of the present invention are about 1.1 h^-1 at about 2.2 h^-1.

Efficiencies in color removal for catalyst compounds are measured by ultraviolet adsorption at 340 nm. In one embodiment, the catalyst compounds of the present invention remove at least about 75% of the color from crude terephthalic acid. In another embodiment, the catalyst compounds of the present invention remove at least about 80% of the color from crude terephthalic acid. In yet another embodiment, the catalyst compounds of the present invention remove at least about 90% of the color from crude terephthalic acid.

Although the invention has been explained in relation to certain embodiments, it should be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it should be understood that the invention described herein is intended to cover such modifications as they fall within the scope of the appended claims.