CS266525B1 - Method of methyl-tertiary butyl ether production - Google Patents

Abstract

Process for the preparation of methyl tert-butyl ether from methanol and isobutene by addition to organic The ion exchanger in several stages rests in the last reaction stage adds a mixture of butane-butene with methanol containing 3 to 5% by weight of methanol in an amount of 10 to 25 wt 100% by weight of the reaction mixture, thereby increasing overall conversion.

Description

The invention relates to a process for the preparation of methyl tert-butyl ether from methanol and isobutene by addition on an organic ion exchanger.

Methyl tert-butyl ether (MTBE) is industrially produced by the addition of methanol with isobutene on an organic ion exchanger. The reaction takes place at temperatures of 50 to 90 ° C and pressures, ensuring the fluidity of all components. The reaction is selective and virtually no by-products are formed. Only in the case of methanol deficiency does dimerization of isobutene begin to occur. The process usually takes place in several stages. In terms of different requirements, these production variants are used industrially.

Option I

Xsobutene, usually contained in the depleted pyrolysis fraction together with other butenes and butanes, is fed together with methanol to the multistage reaction section, where the catalyst selectively reacts with isobutene to form MTBE. The resulting reaction mixture of MTBE and unreacted hydrocarbons is distilled in an elbow from which the butane-butene mixture leaves at the top and MTBE at the bottom. Due to the small excess of methanol over isobutene, isobutene is calculated at isobutene at a purity of MTBE of 96 to 99% conversion. Excess methanol forms an azeotropic mixture with butenes and leaves as an accompanying component with both MTBE and the butane-butene fraction. This method is suitable for maximum operating costs for maximum use of MTBE in motor gasoline. The disadvantage of this method is the low degree of conversion.

Variant II

As in the first variant, methanol is mixed with the depleted fraction containing isobutene before the reaction section. Methanol is added in excess and the next distillation column is fed with a mixture of MTBE, a non-reacting butane-buffet mixture and methanol. Part of the methanol again passes with the butane-butene fraction as the overhead product and most of it, together with MTBE, is taken from the bottom of the column and injected onto another distillation column, where MTBE is separated from methanol, which is returned to the reaction section. Excess methanol in the reaction section ensures a conversion of at least 98% and significantly improves the quality of the butane-butene mixture, which is then suitable for further use. The disadvantage of this method is that the purity of MTBE or an increase in conversion is achieved by increasing both investment and operating costs. Each manufacturer strives to increase the conversion of the ongoing response without additional capital expenditures and thus improve the economy of the whole process.

The use of the present invention allows a substantial increase in isobutene conversion of up to 98% without additional investment costs for all manufacturers working with the first variant of MTBE production.

Process for the production of methyl tert-butyl ether from methanol and isobutene by addition on an organic ionex in several steps, consisting in adding to the reaction mixture stream entering the last reaction step a mixture of butane-butene with methanol containing 3 to 5% by weight of methanol in an amount of 10 to 25% by weight per 100% by weight of the incoming reaction mixture.

The process for the production of MTBE according to the invention uses the principle of shifting the reaction equilibrium by adding methanol before the last reaction step without affecting the deteriorating quality of MTBE and with only partially higher energy consumption in the rectification section of the reaction mixture. One of the most common methods of producing MTBE is used according to the process of the invention, so that the reaction taking place in three reactors connected in series is as follows:

- most of the isobutene and methanol react in the first two reactors up to a conversion of 92% isobutene, i.e. up to about 2.5% by weight of isobutene in the reaction mixture. The concentration depends on the isobutene content in the input fraction,

- a mixture of butane-butenes with methanol is added to the mixture thus reacted and the reaction is continued

CS 266 525 3 in the third reactor so that an excess of methanol increases the conversion up to 97 to 98% of isobutene.

The principle of the present invention is illustrated by way of validated examples.

Example 1

According to the current production method, the full capacity of the fraction with an isobutene content of 44% by weight and a corresponding amount of methanol is injected onto the plant so that the MTBE from the bottom of the distillation column at the outlet of the plant contains 1 to 2% by weight of methanol and the butane-butene mixture as distillation overhead. The columns of the reaction mixture contained 4% by weight of methanol and 2.9% by weight of isobutene, which is in full agreement with the theoretical calculation * for the original production plant. The conversion of isobutene is 96%.

Example 2

The process is carried out according to Example 1, with the difference that 1/4 of the amount of the butane-butene-methanol-mixed overhead distillate produced was added to the reaction mixture stream before the third reactor. The content of isobutene in the reaction mixture and subsequently also in the butane-butene mixture fell below 2% by weight and both the quality of MTBE increased and the amount of methanol decreased. A conversion of 97 to 98% is achieved.

Example 3

The device is injected with the full capacity of the fraction with an isobutene content of 44% by weight and the corresponding amount of methanol so that the methanol content in MTBE is less than 0.5% by weight and a butane-butene mixture with an isobutene content of 3% by weight and methanol leaves the column head. % by weight, which is in full agreement with the theoretical calculation for the original production equipment. By branching 1/4 of the amount of butane-butene mixture added to the reaction mixture before the third reactor as in Example 2, the isobutene content in the reaction mixture and subsequently also in the butane-butene mixture drops below 2% by weight and the methanol content in the butane-butene mixture begins to decrease to 3% by weight. A conversion of min. 97%.

Example 4

The device is injected with the full capacity amount of the fraction with an isobutene content of 44% by weight and the corresponding amount of methanol according to Example 1. A mixture of saturated aliphatic hydrocarbons with methanol in an amount of 1 to 4% by weight of methanol is prepared. The mixture is added before the third reactor to the reaction mixture stream in an amount of 1/10 to 1/4 of the total fraction injection. The conversion of the reaction increases to 97-98% based on the reacted isobutene.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of methyl tert-butyl ether from methanol and isobutene by addition on an organic ion exchanger in several stages, characterized in that a mixture of butane-butene with methanol containing 3 to 5% by weight is added to the reaction mixture stream entering the last reaction stage. of methanol in an amount of 10 to 25% by weight per 100% by weight of the incoming reaction mixture.