CN1074310C

CN1074310C - Catalyst for synthetising dimethyl carbonate from methanol and propylidene carbonate

Info

Publication number: CN1074310C
Application number: CN98106728A
Authority: CN
Inventors: 孙予罕; 赵天生; 韩怡卓; 杨彩虹; 李文彬
Original assignee: Shanxi Institute of Coal Chemistry of CAS
Current assignee: Shanxi Institute of Coal Chemistry of CAS
Priority date: 1998-03-06
Filing date: 1998-03-06
Publication date: 2001-11-07
Anticipated expiration: 2018-03-06
Also published as: CN1228358A

Abstract

The present invention relates to a catalyst for synthetising dimethyl carbonate from methanol and propylidene carbonate, which uses inorganic potassium compounds impregnated on zeolite molecular sieves. The catalyst comprises 11% to 17% of inorganic potassium compounds and 83% to 89% of zeolite molecular sieves according to weight percentage. The catalyst of the present invention has the advantages of high activity and selectivity and repeated use, and is easy to separate through filtration after reactions end.

Description

Catalyst for synthesizing dimethyl carbonate from methanol and propylene carbonate

The present invention belongs to a catalyst for synthesizing dimethyl carbonate from methanol and propylene carbonate.

Dimethyl carbonate belongs to environment-friendly chemicals and has good application prospect in the aspects of being used as an organic synthesis intermediate and an oil additive (catalysis in the production and reaction of dimethyl carbonate which is a large environment-friendly raw material, appl. Catal A: General 1997,155, 133-166). One of the effective methods for the synthesis of dimethyl carbonate by transesterification of methanol and propylene carbonate ("production of dimethyl carbonate and its progress as an oil additive", Energy&Fuels,1997,11,2-29) is shown in the following reaction scheme:

homogeneous catalysts such as alkali metal hydroxides, carbonates, alkoxides, etc. have a better catalytic activity for this reaction ("research on the transesterification of propylene carbonate with methanol to produce DMC" Natural gas chemical 1997,22(5), 1-4). But there is a problem of catalyst separation.

The object of the present invention is to provide a catalyst for the synthesis of dimethyl carbonate from methanol and propylene carbonate, which is easily separated from the product.

The invention is realized by adopting inorganic potassium compound to impregnate zeolite molecular sieve, and the catalyst composition is (weight percentage):

inorganic potassium compound 11-17% zeolite molecular sieve 83-89%

The inorganic potassium compound is potassium hydroxide, potassium nitrate or potassium carbonate.

The zeolite molecular sieve as described above consists of (molar ratio):

SiO₂∶Al₂O₃=(2-50)∶1

the zeolite molecular sieve as described above is preferably of the type A, X, L, ZSM-5.

The preparation method of the invention adopts an impregnation method, namely: roasting molecular sieve at 550 deg.C for 2 hr, performing first ion exchange with 1.0 equivalent concentration potassium nitrate solution at 80 deg.C, filtering, oven drying, roasting at 350 deg.C for 3 hr, performing second ion exchange, filtering, oven drying, roasting at 550 deg.C for 3 hr, performing third ion exchange, filtering, oven drying, and roasting at 550 deg.C for 4 hr. Then, the carrier is dipped into the water solution of inorganic potassium compound according to the catalyst composition, vacuumized, kept stand for 24 hours, dried at 120 ℃, and roasted and activated at 600 ℃ for 4 hours to obtain the catalyst.

Compared with the prior art, the catalyst has the advantages of higher activity and selectivity, easy separation by filtration after the reaction is finished, and reusability.

The examples of the invention are as follows:

example 1

Roasting a molecular sieve at 550 ℃ for 2 hours, performing first ion exchange at 80 ℃ by using a potassium nitrate solution with the equivalent concentration of 1.0, filtering, drying, roasting at 350 ℃ for 3 hours, performing second ion exchange, filtering, drying, roasting at 550 ℃ for 3 hours, performing third ion exchange, filtering, drying, roasting at 550 ℃ for 4 hours to obtain a KX molecular sieve carrier, then soaking KX into a KOH aqueous solution according to the composition (weight percentage) of 16 percent of KOH and 84 percent of KX, vacuumizing, standing for 24 hours, drying at 120 ℃, roasting and activating at 600 ℃ for 4 hours to obtain a catalyst, adding propylene carbonate and methanol into a reaction vessel, wherein the adding amount of the catalyst is 4 percent of the weight of a reaction mixture, heating the reaction temperature to 120 ℃ under the stirring condition, performing reaction for 2 hours, filtering, separating the catalyst from a reaction solution, and analyzing the reaction solution by using GC, the conversion of propylene carbonate was 41.0% and the yield of DMC was 38.5%.

Example 2

The catalyst was prepared from KX molecular sieve support obtained from X type molecular sieve with KOH 12% and KX 88% composition, as in example 1. The reaction solution was analyzed by GC, the conversion of propylene carbonate was 38.1% and the yield of DMC was 35.7%.

Example 3

A KA molecular sieve support was prepared using the type A molecular sieve, and the catalyst was prepared with a KOH of 17% and KA of 83%, as in example 1. The reaction solution was analyzed by GC, the conversion of propylene carbonate was 25.3% and the yield of DMC was 23.6%.

Example 4

According to K₂CO₃The catalyst was prepared at 16% KX of 84% composition, as in example 1. The reaction solution was analyzed by GC, the conversion of propylene carbonate was 36.7% and the yield of DMC was 35.1%.

Example 5

Push against KNO₃The catalyst was prepared at 17% KX of 84% composition as in example 1. The reaction solution was analyzed by GC, the conversion of propylene carbonate was 36.0% and the yield of DMC was 29.6%.

Example 6

Preparing KZSM-5 molecular sieve carrier from ZSM-5 type molecular sieve, and preparing thecarrier by KNO₃16% of KZSM-5 and 84% of KZSM-5, the catalyst was prepared, the remainder being the same as in example 1. The reaction solution was analyzed by GC, the conversion of propylene carbonate was 33.4% and the yield of DMC was 28.0%.

Claims

1. A catalyst for synthesizing dimethyl carbonate from methanol and propylene carbonate is characterized in that:

inorganic potassium compound 11-17 wt% and potassium-containing zeolite molecular sieve 83-89 wt%

2. The catalyst for synthesizing dimethyl carbonate from methanol and propylene carbonate according to claim 1, wherein the potassium-containing zeolite molecular sieve comprises the following components in mole ratio:

SiO₂∶Al₂O₃=(2-50)∶1

3. a catalyst for the synthesis of dimethyl carbonate from methanol and propylene carbonate according to claim 1, characterised in that the inorganic potassium compound is potassium hydroxide, potassium nitrate or potassium carbonate.

4. The catalyst for the synthesis of dimethyl carbonate from methanol and propylene carbonate according to claim 2, characterized in that the zeolite molecular sieve containing potassium is of the A, X, L or ZSM-5 type.