JPS6144849B2 - - Google Patents

Abstract

Methyl tertiarybutyl ether is produced by reacting isobutylene or a hydrocarbon mixture containing isobutylene with methanol in the presence of a perfluorocarbon polymer having sulfonic acid groups as a catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing methyl tertiary butyl ether (hereinafter abbreviated as MTBE), and more specifically, the present invention relates to a method for producing methyl tertiary butyl ether (hereinafter abbreviated as MTBE), and more specifically, a method for producing methyl tertiary butyl ether (hereinafter abbreviated as MTBE), and more specifically, a method for producing methyl tertiary butyl ether (hereinafter abbreviated as MTBE). The present invention relates to a method for producing MTBE.

MTBE is a very useful compound as an octane improver for gasoline, and it is known that it can be produced from isobutylene and methanol using a catalyst. Examples of catalysts in this case include:
(1) Mineral acids such as sulfuric acid or aromatic sulfonic acids (U.S. Patent No. 2720547), (2) Metal sulfates (Japanese Patent Publication No. 1972-
12168), (3) Silica-phosphomolybdate (U.S. Pat. No. 3,135,807), (4) Heteropolyacid (Japanese Patent Application Laid-open No. 1989-
14909), (5) Strong acid type ion exchange resin (Unexamined Japanese Patent Publication No. 14909-
6912, 52-62206, 53-50113, etc.) are known.

However, when viewed as an industrial catalyst, these catalysts have the following problems and are not necessarily satisfactory.

That is, in (1), it is not easy to separate the catalyst from the reaction mixture, and there is also the problem of waste acid. (2) The catalyst easily decomposes at high temperatures. In (3), olefin polymerization tends to occur. (4) is not highly active. The materials conventionally used as suitable materials for (5) include sulfonated resins obtained by copolymerizing styrene and polysaturated compounds such as divinylbenzene, and resins obtained by condensing phenolsulfonic acid with formaldehyde. It is gel-like or giant porous.

However, the MTBE production reaction was 18.6Kcal/mol
Since the reaction is accompanied by exothermic heat (400°K), if these resins are used in a fixed bed system where temperature control is difficult, deterioration due to resin decomposition due to heat, acid elution, etc. will be significant. On the other hand, in a fluidized bed reaction where the temperature can be easily controlled, acid elution from the resin and its deterioration are likely to occur due to wear and the like. In such a case,
The eluted acid decomposes the generated MTBE, so
As disclosed in JP-A No. 53-65809, consideration must be given, such as providing a special step for removing acid during the purification process.

The present inventors have completed the present invention as a result of intensive studies aimed at solving these problems that have tended to accompany conventional inventions.

That is, the present invention provides a method for producing MTBE, which comprises using a perfluorocarbon polymer having a sulfonic acid group as a catalyst in producing MTBE by reacting isobutylene or an isobutylene-containing hydrocarbon with methanol in the presence of a catalyst. It provides:

The perfluorocarbon polymer having a sulfonic acid group used as a catalyst in the present invention may be a copolymer of a vinyl fluoride compound having a sulfonic acid group and another vinyl monomer, or a copolymer thereof such as divinylbenzene or a copolymer containing divinylbenzene. Those crosslinked with a crosslinking agent such as a fluorine polyunsaturated compound are used. Such catalysts include, for example,
Commercially available from Dupont (Nafion®)
Copolymers of sulfonyl fluoride vinyl ether and tetrafluoroethylene, such as,
general formula A polymer represented by the following formula, where m is 5 to 13.5, z is an integer (especially 1 to 3), and n, which represents the degree of polymerization, is several hundred to several thousand, typically about 1000. It is. Such polymers are produced by copolymerizing tetrafluoroethylene and the corresponding perfluorosulfonyl ethoxy vinyl ether to obtain the desired m value, and if necessary, hydrolyzing the sulfonyl fluoride type pendant chain terminals. It can be prepared by converting it into a sulfonic acid form.

Among the perfluorocarbon ion exchangers that are commonly used in the form of a membrane to physically isolate the anolyte and catholyte and allow sodium ions to pass from the anolyte to the catholyte in chloralkali electrolysis, cation exchangers with sulfonic acid groups are used. Ion exchangers can also be used in this invention.

Since the catalyst is active only in the acid form, if it is in the salt form, it should be treated with a mineral acid such as hydrochloric acid or nitric acid to convert it into the acid form, and then dried. The ion exchange capacity of the catalyst is desirably about 0.3 mg equivalent/g dry catalyst or more in order to have appropriate activity for the reaction, and about 2.0 mg equivalent/g dry catalyst or less in order to avoid side reactions. It is desirable that More preferably about 0.5 to about 1.5
mg equivalent/g dry catalyst.

From the same point of view, the amount of catalyst used in the reaction is about 0.001 to about 20 parts by weight of raw material alcohol.
It is preferably within the range of parts by weight, and more preferably within the range of about 0.01 parts by weight to about 10 parts by weight. When using a catalyst, the shape is as follows:
It may be in the form of powder, granules, or pellets (or film).

Perfluorocarbon polymers having sulfonic acid groups are of the so-called super acid type and are said to be good catalysts for the oligomerization of isobutylene, one of the raw materials of the present invention (as disclosed in U.S. Patent No.
4065512), there was a concern that undesirable side reactions would occur when used in the present invention, but it has been confirmed that such side reactions do not actually pose any problems as long as they are used under the conditions of the present invention. However, when the catalyst of the present invention is used in the form of a membrane, it is desirable to avoid long-term reactions at high temperatures in order to prevent oligomerization of isobutylene.

Isobutylene, one of the raw materials of the present invention, is not limited to highly pure isobutylene, but may also be a mixture containing isobutylene. In addition to isobutylene, the mixture includes 4-carbon atoms such as 1-butene, 2-butene, butadiene, n-butane, and isobutane.
or other hydrocarbons. As the other raw material, methanol, industrially produced methanol may be used as is. The molar ratio of isobutylene to methanol is not particularly limited, but usually about 0.1 to about 10 methanol to 1 part isobutylene is used. The reaction can usually be easily carried out without a solvent, but may be carried out in a solvent if necessary.

The reaction temperature is usually between 0 and 200°C,
Since the reaction rate is slow at low temperatures, and undesirable side reactions may occur at high temperatures, the temperature is preferably in the range of about 30 to about 150°C, more preferably in the range of about 50 to about 120°C.

The reaction pressure can be from normal pressure to the vapor pressure of the reaction mixture at the reaction temperature. However, in terms of equilibrium, it is preferable to have a certain degree of pressure, generally in the range of normal pressure to about 100 atm, preferably about 2 to about 80 atm, more preferably about 3 to about 50 atm. .

If the vapor pressure of the reaction mixture is less than the desired reaction pressure, the pressure can be brought to a predetermined level by sealing a gas that does not participate in the reaction in the reaction vessel. As such a gas, for example, an inert gas such as helium or argon, nitrogen, air, etc. can be used.

The perfluorocarbon polymer having sulfonic acid groups used as a catalyst in the present invention has extremely excellent properties in terms of wear resistance. This reaction can be carried out particularly preferably by a phase fluidized bed reaction. In such a reaction method, in order to easily separate the catalyst from the reaction mixture, the catalyst is in a solid form such as powder, granules, granules, or pellets, and the particle size is about 1 μm or more, preferably about 1 μm or more. It is preferable to use a particle size of 10 μm or more, most preferably a particle size of about 0.01 to about 5 mm.

The reaction is carried out by fluidizing the catalyst in a liquid phase by stirring, etc., and the stirring speed at this time is about 10 to about 2,000 revolutions per minute, more preferably about 20 to about 1,000 revolutions per minute, or equivalent thereto. The reaction can be carried out advantageously by using shear energy,
Moreover, almost no deterioration of the catalyst is observed.

In addition, the perfluorocarbon polymer having a sulfonic acid group used as a catalyst in the present invention is
Since it also has extremely excellent heat resistance, it is possible to carry out the reaction suitably in a fixed bed reaction system without causing deterioration of the catalyst.

These reaction methods can be carried out either continuously or batchwise. However, it is clear that continuous reaction is more advantageous from an industrial perspective.

As is clear from the above description, if a perfluorocarbon polymer having a sulfonic acid group is used as a catalyst, MTBE can be industrially advantageously produced from isobutylene or an isobutylene-containing hydrocarbon and methanol.

EXAMPLES The present invention will be explained in more detail below using Examples, but the present invention is not limited to these Examples.

Example 1 20 g of a potassium salt of a perfluorocarbon polymer having a sulfonic acid group (Nafion 501, trademark, manufactured by Du Pont) having the structure of the formula () and n of about 1000 was added to a 20% aqueous nitric acid solution at room temperature. After stirring for 20 hours, it was filtered and washed with about 1 ml of pure water. This was dried at 120° C. for 5 hours under reduced pressure to obtain an H-type dry catalyst. The ion exchange capacity of the catalyst thus obtained was 0.74 mg.
At equivalents/g dry catalyst, the average particle size was approximately 0.5 mm. 2.5 g of this catalyst and 20.08 g of methanol were weighed into an autoclave having an internal volume of 200 ml and equipped with a magnetic stirrer. Add to this 46.05g of liquefied isobutylene.
The reaction was carried out at a stirring speed of 700 rpm in an electric furnace with a set temperature of 80°C. (Initial pressure 10Kg/
cm ² ) After the reaction started, the temperature in the reactor increased,
After 14 minutes, the temperature rose to a maximum of 95°C. Thereafter, the temperature gradually decreased, and 45 minutes after the start of the reaction, the temperature in the reactor decreased again to 80°C. (The pressure at that time is 2.5
Kg/ ^cm2 ) At this point, the reaction was stopped by cooling the container, and gas chromatography analysis of the reaction solution revealed a methanol reaction rate of 82.1% and a selectivity to MTBE of 99.7%. Ta. Further, dimethyl ether and isobutylene polymers were not detected at all. When neutralization titration was performed on the catalyst after the reaction, it was found that the acid component of the catalyst had not decreased at all compared to before the reaction.

Example 2 The amount of the catalyst prepared in Example 1 was 1.5 g, methanol was 20.04 g, and isobutylene was 44.33 g.
The reaction was carried out in the same manner as in Example 1, except that g was used. The reaction was slightly slower than in Example 1, and the temperature rose to a maximum of 83°C. The reaction was stopped 100 minutes after the start of the reaction (the pressure at that time was 3 Kg/cm ² ). Based on gas chromatography analysis of the reaction solution, methanol reaction rate and MTBE selectivity were 73.4%.
and 99.8%, respectively. No polymers of dimethyl ether and isobutylene were detected in the reaction product. Further, no decrease in the acid component of the catalyst was observed.

Comparative Example: 2.5 g of fluorine-free sulfonic acid type cation exchange resin (Amberlyst 15, trademark) was used instead of the perfluorocarbon polymer having sulfonic acid groups, 20.27 g of methanol, and 46.05 g of isobutylene.
The reaction was carried out in the same manner as in Example 1 except that g was used. Six minutes after the start of the reaction, the maximum temperature rose to 100°C. The reaction was stopped 45 minutes after the start of the reaction, and gas chromatography analysis of the reaction solution revealed that the methanol reaction rate and MTBE selectivity were 83.4% and 99.7%, respectively. When the acid component of the catalyst was measured by neutralization titration, it was 5.10 mg equivalent/g dry catalyst before use, and 4.93 mg equivalent/g after reaction.
The dry catalyst had been reduced.

Claims (1)

[Claims] 1. In producing methyl tert-butyl ether by reacting isobutylene or an isobutylene-containing hydrocarbon with methanol in the presence of a catalyst,
A method for producing methyl-tertiary-butyl ether, characterized in that a perfluorocarbon polymer having a sulfonic acid group, which is a copolymer of tetrafluoroethylene and perfluorosulfonyl ethoxy vinyl ether, is used as a catalyst. 2. The method of claim 1, wherein the perfluorocarbon polymer having sulfonic acid groups has an ion exchange capacity of about 0.5 to 1.5 mg equivalent/g polymer. 3 General formula before polymerization of perfluorocarbon having sulfonic acid group (wherein m is a number from 5 to 13.5, z is an integer from 1 to 3, and n is about 1000). 4. Any one of claims 1 to 3 in which the reaction is carried out in a liquid phase at a temperature of about 30 to 150°C and a pressure of about 2 to about 0 atmospheres using a catalyst with a particle size of about 0.01 to about 5 mm. The manufacturing method described in the section. 5. The manufacturing method according to claim 4, wherein the reaction is carried out by suspending a catalyst in a liquid phase. 6. The manufacturing method according to claim 4, using a catalyst as a fixed bed.