Preparation method and application of eggshell type composite metal catalyst

Abstract

The invention relates to an eggshell type composite metal oxide catalyst applied to gas phase oxidation of isobutylene/tert-butanol for synthesis of methylacrolein. A spherical carrier and a binder are added during the preparation of the catalyst, so a metal salt undergoes a reaction on the surface of the spherical carrier and adheres onto the surface of the spherical carrier; and a part of the binder is removed by roasting so as to obtain the eggshell type composite metal oxide catalyst. The catalyst provided by the invention is simple in preparation process and low in cost, and has excellentcatalytic performance in the gas phase oxidation of isobutylene/tert-butanol for synthesis of methylacrolein; and the catalyst has long catalytic life and is suitable for industrialization.

Description

technical field [0001] The invention relates to a preparation method of an eggshell-type composite metal oxide catalyst and its use in the reaction of synthesizing methacrolein by gas-phase oxidation of isobutene / tert-butanol, belonging to the field of catalyst preparation and application. Background technique [0002] As an important organic chemical raw material and industrial intermediate, methyl methacrylate (MMA) is mainly used in the production of plexiglass (PMMA), light guide plates, light guide fibers, etc. Due to the excellent physical and chemical properties of PMMA, it is widely used in LED, aviation and Important national industries such as rail transit have important applications. The acetone cyanohydrin method is the traditional production process of MMA. Due to the use of highly toxic hydrocyanic acid and corrosive sulfuric acid in the production process, it seriously pollutes the environment, so a new alternative process that meets the requirements of green ...

AI Technical Summary

Problems solved by technology

Both processes are green processes with simple processes and low operating costs. As the key reaction steps of the two processes, the catalyst used for the oxidation of isobutene / tert-butanol to methacrolein is mainly Mo-Bi-Fe-Co-O Based on composite oxides, trace elements are added to the above basic components to achieve relatively high catalyst activity, but there are two difficult problems in the industrial application of these catalysts: 1. Strong heat release leads to catalyst performance decline, 2. The reaction of isobutene is not complete so as to affect the activity of the subsequent reaction catalyst

[0004] In order to solve the first problem, the patents US5728894 and US7012039 disclose a method to suppress the loss of the active component Mo by adding components with heat resistance and reduction resistance, so as to prolong the life of the catalyst, but this cannot be achieved from Fundamentally solve the problem; on this basis, patents CN1210511A, CN145946A and CN1048540A respectively improve the thermal conductivity of the catalyst by loading and adding inert substances to dilute the catalyst, thereby inhibiting the loss of the Mo component due to high temperature during the reaction process, but these methods It not only reduces the catalyst activity and product yield more or less, but also makes the preparation process and loading process of the catalyst more complicated.

[0005] The second problem focuses on the three-step method. The catalyst for the oxidation of methacrolein to methacrylic acid is very sensitive to isobutene, and too much residual isobutene will cause the catalyst to be poisoned and deactivated. Therefore, in order to improve the economics and Catalyst life for subsequent reactions, the isobutene in the first step needs to be reacted as completely as possible

Although a lot of progress has been made in the conversion rate, it still does not meet the requirements of the catalyst for the oxidation of methacrolein to methacrylic acid, and it also leads to a decrease in the selectivity of methacrolein.