A kind of preparation method of alumina-coated transesterification catalyst

Abstract

The invention discloses a preparation method of an alumina-coated transesterification catalyst, in particular an Al 2 O 3 Coated K 2 O / Na 2 O‑WO 3 The preparation method of catalyst, the method starts with K 2 O‑WO 3 or Na 2 O‑WO 3 as the core center, by coating Al 2 O 3 get K 2 O / Na 2 O‑WO 3 @Al 2 O 3 Composite structure catalyst, used in the reaction of propylene glycol carbonate and methanol to dimethyl carbonate, K 2 O / Na 2 O‑WO 3 with Al 2 O 3 Has a synergistic effect, the Al in the composite catalyst 2 O 3 Provide high specific surface area and better pore distribution for adsorption and screening of reactive molecules, K in the catalyst core center 2 O / Na 2 O‑WO 3 The surface reactant undergoes transesterification to generate dimethyl carbonate, which ultimately effectively improves the selectivity of the target product dimethyl carbonate, and the catalyst has better transesterification activity in the low temperature region (60-80°C).

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and relates to a kind of Al 2 O 3 Coated K 2 O / Na 2 O-WO 3 Catalyst, be specifically related to a kind of K that prepares the coating structure of dimethyl carbonate with transesterification 2 O / Na 2 O-WO 3 @Al 2 O 3 The preparation method of type catalyst. Background technique [0002] Dimethyl carbonate is an important green chemical raw material. It has a wide range of uses and can be used as a solvent, gasoline additive, etc. It is also an important raw material for the synthesis of polycarbonate through propylene carbonate. At present, many researchers at home and abroad are actively researching and promoting new carbonic acid. The method for synthesizing dimethyl carbonate, in which methanol is widely sourced and cheap as a raw material, and the process for synthesizing dimethyl carbonate by transesterification method is mild, and can co-produce ethylene glycol or 1,2-pro...

AI Technical Summary

Problems solved by technology

[0003] An important factor affecting the development of transesterification technology to synthesize dimethyl carbonate is the development of high-efficiency catalysts. The homogeneous catalysts with alkali metal hydroxides and alkali metal alkoxides as typical catalysts have fast reaction speeds and high product yields. Attention has been paid to homogeneous catalysts, but the homogeneous catalysts are not easy to separate from the product, the operating cost is high, and the stability is poor, which increases the difficulty of its promotion. Difficulties in separation and recovery, but the target product selectivity and yield of this type of catalyst are low;

[0004] For example, Mobil Corporation (patent US5498743) has successfully developed silica gel as a carrier and loaded alkaline earth metal halide salts as a transesterification catalyst, but the yield and selectivity are low. Patent CN1228358A uses X molecular sieves after potassium ion exchange as a carrier , KOH-KX catalyst is prepared by impregnation method, which can be reused and the product is easy to separate, but the conversion rate of propylene glycol carbonate is only 41%; patent CN 1431053A, also developed a heterogeneous catalyst, with phenolic resin as the main carrier, loaded Alkaline earth metal carbonate, propylene glycol carbonate conversion rate and dimethyl carbonate yield are all better under high temperature, but 80 ℃ propylene glycol carbonate conversion rate is only 68.4%, and reaction time is long; Therefore, the industry of heterogeneous catalyst There are still technical bottlenecks in the promotion, and key breakthroughs are needed

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