Method of obtaining tertiary ethyl butyl ether

<td>POLAND REPUBLIC CHINA</td><td>Egi. BUSINESS PATENT DESCRIPTION</td><td> 137</td><td> 664</td>

<td></td><td>Additional patent for a patent</td><td></td><td></td>

<td>tlflr</td><td>Reported: 82 04 08 (P. 235879)</td><td></td><td></td>

<td>OFFICE PATENTOWT</td><td>Priority: 81 04 10 Italy The application was announced: 82 10 25</td><td colspan="2">Int. Cl? C07C 43/04</td>

<td>PRL</td><td>Patent description published: 1987 07 31</td><td></td><td></td>

Inventor: Giancarlo Paret

Patent holder: Snamprogetti SpA, Milan (Italy)

Method for producing methyl ether-II. butyl

The present invention relates to a process for producing methyl tert-butyl ether from a hydrocarbon feed containing isobutene and from methanol. The process of the present invention also applies in its entirety to all other III ethers. alkyl because the differences in the boiling points of the substrates and products are of the same order of magnitude as in the case of III-methyl ether. back.

Known publications give a method for producing methyl tert-butyl ether (MTBE) by isobutene reaction, occurring in various percentages in the hydrocarbon fraction C₄ with methanol, in the presence of a suitable catalyst containing sulfone styrene-divinylbenzene resins, maintained at a temperature ranging from ambient temperature to about 100 ° C. In practice, isobutene is not available on an industrial scale and therefore we will refer to the above mentioned hydrocarbon fraction C₄containing isobutene. A balance is established in this response. If the amount of methanol taken into the reaction is close to the stoichiometric amount, then at temperatures where the reaction rate is satisfactory, the conversion rate of isobutene is 90% or slightly more.

In the event that a higher conversion value is required, excess methanol should be taken into the reaction, which must then be separated from the reaction products and recycled, which allows a conversion rate exceeding slightly 95% under satisfactory process conditions or, after isolation of the reaction products direct the remaining mixture to the second reaction stage, in which conditions similar to stoichiometric conditions are also maintained, allowing a conversion rate of around 99% to be achieved. However, the difficulty is that in order to carry out this process it is necessary to strip C hydrocarbons twice₄ and the use of two reactors and two distillation columns, which significantly increases investment outlays and operating costs. Recently, in accordance with European Patent No. 8,860, a method has been developed to eliminate the abovementioned difficulties, consisting in introducing a mixture of isobutene and methanol into a distillation column filled with an appropriate catalyst, enabling the production of MTBE and simultaneously fulfilling the role of filling the column, which allows the simultaneous production of MTBE and separation of MTBE from unreacted hydrocarbons. C₄.

The method described in this European patent specification No. 8,860 enables simultaneously conducting a chemical reaction and fractionation of the reaction mixture in a distillation column filled in 2/5 of height with glass spirals, and in 3/5 with catalysts placed in vertically located pockets

137 664 I | made of stainless steel mesh. In this method, the reactants are led to a column in the feed zone in a glass filling, whereby these reagents pass through a solid catalyst bed, which is also a distillation and reaction zone, in which the reactants react with the help of a catalyst, forming a product mixture and substrates, which in turn undergoes fractionation in the bed, which allows the separation of lower boiling components from the top of the column and the removal of higher boiling components from the bottom of the column, in which the lacquer is mentioned, the chemical reaction and the fractionation take place simultaneously in the whole catalyst bed, which simultaneously serves as a catalyst and a column fill.

! As for the production of methyl tert-butyl ether by the method described in the above-mentioned European Patent No. 8,860, it consists in the fact that a mixture containing isobutene and normal butene and methanol is introduced into the feed zone of the above-described distillation column. which then, going up, contacts the solid cation exchange resin in acid form, which is also the reaction and distillation zone of the column, in which the reaction of isobutene with methanol to form methyl tert-butyl ether occurs, which in turn in the mixture with normal butene undergoes fractionation, as a result of which the fraction containing normal butene is collected from the top of the column above the feed point, and from the bottom of the column below the power point, ether is being received.

However, the method described in this patent has a number of weaknesses related to the Takt that the catalyst is also the filling of the distillation column and therefore must meet additional special requirements, in particular it is required that its presence does not affect the pressure drop in the installation. For this reason, it is used in bags forming belts, leaving free space for the flow of vapors and condensate, which, on the other hand, is difficult to prepare and pack in a column. Another disadvantage of the method described in this patent is the presence of a gas phase as a continuous phase and a liquid phase as the dispersed phase inside the column. This leads to low MRBE yields because the reaction practically occurs in the gas phase. It also creates the possibility of significant amounts of dimer, because there is an alcohol deficiency in the gas phase.

It has now been surprisingly found possible to remove all of the aforementioned disadvantages of the process by carrying out both the reaction of formation of III-alkyl alkyl ether (e.g., MTBE) and its separation from hydrocarbons and accompanying compounds, in a single plate fractionator in which some sections are equipped with beds of catalyst in the form of granules based on a sulfone-styrene-vinyl vinyl benzene resin suitable for the production of III-alkyl ether (e.g. MTBE), and some sections are provided with shelves. 'In the process of the invention, a hydrocarbon feed containing Isoolefin compounds is introduced into a fractionation plate column in which some sections are filled with a catalyst bed consisting of a sulfonated styrene-divinylbenzene resin, which the catalyst is immersed in a liquid hydrocarbon phase containing methanol, with 8 sections being used, 6 of which are above, and 2 below the supply point, and the sections provided with shelves contain 6 shelves, with

In total, methanol is introduced into the upper part of the section filled with catalyst, maintaining a temperature of 40 40-130 ° C at a pressure of 500 kPa and 80-170 ° C at a pressure of 1000 kPa and conducting the process in the pressure range &lt;500-1000 kPa. From the bottom of the column, substantially pure ether is collected as the product, and from the top of the column (product containing the introduced hydrocarbons and alcohol in the form of azetrope with the unreacted hydrocarbons introduced is withdrawn.

The process according to the invention is carried out at a pressure of 500 to 1000 kPa. In the process of the invention, the hydrocarbon feed containing isoolefin compounds is fed to the plate column at a location such that at least two plates with a catalyst bed are above and at least one plate with a catalyst is below the feed stream inlet. Vapors formed in the fractionation column boiler pass through the catalyst beds, of which there are at least three in the column, and methanol and isobutene react in the liquid phase covering the catalyst bed. The catalyst is used in the form of spherical granules with a diameter of 0.5 mm to 1 mm, with a thickness of each catalyst bed of the order of 1 m. The liquid on each shelf with the catalyst flows to the lower distillation shelf through one or more overflow baffles arranged so that the catalyst bed is always covered with liquid. The catalyst is maintained in each section in such a way that the bottom and top of the bed are grids that prevent the bed from scattering.

According to the known method described in European Patent No. 8,860, the reaction takes place in a gas phase, because in the packed column this phase is a continuous phase. This promotes the formation of dimers, isobutene and other by-products, especially 2,4,4-trimethylpentene. In the gas phase, according to European Patent No. 8,860, methanol is in excess and some of the isobutene forms dimers reacting with a further isobutene molecule. In the process according to the invention, in contrast to the above process, the continuous phase in the column is the liquid phase, while the gas phase is the dispersed phase * Because in the liquid phase methanol is in excess and the isobutene fully reacts with methanol, side reactions of isobutene dimer formation under these conditions are effectively inhibited. Due to the fact that in the process according to the invention the catalyst is separated from the fractionation zone and the liquid phase is a continuous phase, there is no pressure drop in the column.

137 664 3

The use of a distillation plate column and thereby eliminating the disadvantages of the known method in which the process is carried out in a packed distillation column, and above all the elimination of isobutene losses by its dimerization, gave an unexpected effect that could not have been foreseen.

The invention is further illustrated in the attached drawing, showing one of many possible ways of implementing it. In Figure 1, it indicates fractionation shelves, 2 - fractionation shelves filled with catalyst 3, which is kept in a fixed position by the grids 4 and 5. The flow of liquid through the catalyst bed is indicated by arrows 6, and the flow of vapors from the bottom of the column to its top is indicated by arrows 7. One of many possible embodiments of the invention is described below.

An example. The distillation column was constructed of tubular sections 10 cm in diameter and 100 cm in length with flanges, each containing six distillation cap shelves with two caps on each shelf. The column consists of 1 meter sections, filled with catalyst, separated from each other by sections with six fractionation plates, with a total of six sections above the feeding place of the column, and two sections below. A 2 kg / h mixture of hydrocarbons C was introduced into the column₄containing 50% isobutene. The 1: 1 deposition rate was maintained. 575 g of methanol was introduced into the column with phlegm. The process was carried out at a pressure of 800 kPa, at a temperature of 60 ° -150 ° C. A product containing 1035 g of a C4 hydrocarbon mixture containing 30 g of methanol and 5g of isobutene was collected from the top of the column. 1540 g of virtually pure MTBE was collected from the bottom of the column. .

Comparative example. The method according to the invention was compared with Example 3 of European Patent No. 8,860. A feed containing 20% ​​methanol, 39.9% C hydrocarbons was introduced into the device used in the example described above.₄ other than isobutene, 39.9% isobutene, and 0.2% water at a rate of 1 kg / h per 1 kg of catalyst. The following results were obtained - (in brackets the values ​​obtained according to the invention): from the top of the column a stream was obtained containing 40.8% (44.3%) of the initial feed containing 96.0% (90.0%) of hydrocarbons C₄ other than isobutene, 1.3% (10.0%) of isobutene, 0.7% (0.0%) of methanol and from the bottom of the column a stream containing 0.6% (0.6%) of tert-butyl alcohol, 91.7% (99.0%) MTBE, 7.7% (0.4%) of diisobutene; MTBE yield was 54.3 g / 100 g of raw material introduced (55.14 g / 100 g).

The difference between the two tests was that in the method according to the invention the catalyst was immersed in liquid, while in the method according to European patent No. 8 860 it was in bags and was not immersed in liquid.