CS248641B1 - Zeolites to heterogeneous catalytic conversion of acetone to i-butene - Google Patents

Abstract

The use of zeolites, whose general formula in the anhydrous state is in which x takes on values of 0.05 to 0.95 and y takes on values of 1 to 200, for the heterogeneous catalytic conversion of acetone to i-butene at elevated temperatures and at least atmospheric pressure.

Description

The invention relates to a heterogeneously catalytic selective conversion of acetone to isobutene and solves the problem of conversion with high yield and high selectivity.

Isobutene is an important raw material for the production of industrially desired methyl tert-butyl ether / MTB12, which replaces toxic tetraethyl lead in high-octane gasolines and for the production of polyisobutene. Isobutene for the production of MTBE or polyisobutene has so far been obtained from the C-4 fraction after the pyrolysis of naphtha. The highly selective heterogeneous catalytic conversion of acetone to isobutene has not been addressed in the literature.

Based on an extensive series of experiments with red catalysts, it has been found according to the invention that zeolts whose general formula in the anhydrous state is

H ,. _x Na _x AlSi _y 2 _{/ y + 1 /} 'wherein x is 0.05 to 0.95 and y is 1 to 200, to heterogeneously catalyze the conversion of acetone to i-butene at elevated temperature and at least atmospheric pressure.

When using zeolites of this composition as the catalyst, the acetone conversion proceeds with high selectivity and yield. The high activity of zeolites is due to the presence of highly reactive acid-base sites. At the same time, their crystalline structure and the content of Si and Al ensure their high stability - durability during acetone conversion and catalyst regeneration by oxygen at temperatures of 200 to 600 ° C.

In summary, the advantage of the selective acetone conversion process of the present invention is the high yield of isobutene and the very good service life of the zeolite catalysts. Another advantage is the high activity and selectivity of the zeolites and their easy availability, or a technologically simple and easily reproducible preparation. In addition, their structural stability during acetone conversion and their simple activation and reactivation.

The process for the selective conversion of acetone to isobutene can be carried out intermittently or preferably continuously. The catalyst itself may be placed in a fixed or fluidized bed. The resulting isobutene is isolated after product reaction by distillation, rectification or extraction distillation. In the production of MTBE, the crude product can be used directly without separation.

The advantages of the method of converting acetone to isobutene are evident from the following examples, which are not intended to limit the invention in any way.

Example 1 g of zeolites having the composition Ηθ jNhq ΙΙΙΙΙ Οθ, which corresponds to the crystallographic structure of the faujasite zeolites, were introduced into a flow reactor. The acetone conversion was carried out at 300 ° C under normal pressure and loaded with 11 g of acetone per 1 g of catalyst per hour. The total acetone conversion over 3 hours was 53%, with conversion to isobutene 33%, selectivity 62%.

and

Example 2

The acetone conversion was carried out in the same manner as in Example 1, except that a zeolite having a composition Ηθ θΝβ ₀ gAlSi ^ 2 ° 20 corresponding to the crystallographic structure of the erionite zeolites was used as catalyst and the conversion was carried out at 350 ° C. The total acetone conversion over 7 hours was 29%, the conversion to isobutene was 27% and the selectivity was 92%.

Example 3

The acetone conversion was carried out in the same manner as in Example 1, except that it was used as a catalyst having the composition Ηθ γΝβθ ^ AlSi,? 3 ^ 24 6 ´ corresponds to the crystallographic structure of zeolite mordenite and the conversion was carried out at 350 ° C. Total acetone conversion was 22% over 15 hours, 12.1% isobutene conversion and selectivity 55 The zeolite was then activated at 400 ° C with an air stream for 5 hours. The overall conversion of acetone to isobutene and selectivity were the same (ie 22% and 55 36) after reactivation as before.

Example 4

Acetone conversion is carried out in the same manner as in Example I but with the difference that it was used as a catalyst a zeolite having a composition ^^ _Q H ₀ 05 ° 402 200 ^Alsi '^ ^which corresponds to the crystallographic structure of ZSM-11th Total acetone conversion over 10 hours was 20%, isobutene conversion 16%, selectivity 81 36.

Example 5

The acetone conversion was carried out in the same manner as in Example 1, except that zeolite having the composition Ηθ gNa _{Q (} AlSiig gOg. 5), which corresponds to the crystallographic structure of the zeolite ZSM-5, was used and the reaction temperature was 350 The total acetone conversion over 15 hours is 50 36, the conversion to isobutene 42%, and the selectivity 85 85.

These examples show that the selective conversion to isobutene takes place on zeolite-type catalysts of various compositions with very good results, i.e. with a yield of 12 to 42%, a total conversion of 20 to 53% and a selectivity of 55 to 92 36.

Claims (1)

Use of zeolites whose general formula in the anhydrous state is H ,. _x Na _y O _x AlSi _{2 / y + y} in which x takes values from 0.05 to 0.95 and y takes values from 1 to 200, the heterogeneous catalytic conversion of acetone and i-butene at elevated temperatures are employed, and at least atmospheric pressure.