Catalyst, preparation method thereof and application in preparation of unsaturated aldehyde (acid)

Abstract

The invention provides a catalyst, a preparation method thereof and an application in preparation of unsaturated aldehyde (acid). The catalyst has the characteristics of high activity, good heat resistance, long service life and the like. Meanwhile, the product selectivity and yield are higher when the catalyst is used for catalyzing unsaturated olefin for preparation of unsaturated aldehyde (acid). The catalyst comprises a core catalyst, an inner catalyst, a middle catalyst and an outer catalyst sequentially from inside to outside; all the catalysts have similar thermal expansion coefficientsin the range of (6.5-7.5)*10<-6> m / m.K; the composition and mass ratio of all the catalysts of the coated catalyst are shown in the following general formula: (Moa0BibFecCodNieAfOx):m(Moa1NbgVhWiBjOy):n1(Moa2PbkAll1Sip1Cq1Oz1):n2(All2Sip2Dq2Oz2).

Description

technical field [0001] The present invention relates to a multi-protection layer catalyst and its preparation method, and the application of the catalyst in the preparation of corresponding unsaturated aldehydes (acids) by catalyzing the selective oxidation of unsaturated olefins, especially in the production of acrolein (acid) or isobutylene by oxidation of propylene Application in the oxidation of methacrolein (acid). Background technique [0002] Unsaturated aldehydes (acids) are used in a wide range of fields, and one of the representative products is acrylic acid and esters. Its application fields cover coatings, adhesives, chemical fibers, papermaking, leather, building materials, plastic modification, synthetic rubber, radiation curing water treatment agents and other industries. The methods for the production of acrylic acid on an industrial scale generally include the chlorohydrin method, the high-pressure Reppe method, the propiolactone method, the Dorr-Badi she m...

AI Technical Summary

Problems solved by technology

It can be seen that in the current patent reports, in the reaction of isobutene to MAL, the selectivity is mostly between 85% and 90%.

[0004] In addition, there is a strong exothermic process in the oxidation of unsaturated olefins such as propylene and isobutene to unsaturated aldehydes (acids), and the catalyst has been operating at a high temperature for a long time. This requires the catalyst to have excellent strength, and the catalyst is composed of various element compounds. Initiate cracks in the catalyst, thereby weakening the strength of the catalyst, causing the catalyst to be crushed, the bed pressure difference rises, and the effective product continues to be deeply oxidized to form carbon oxides, and the heat release of carbon oxides is an order of magnitude higher than the normal reaction heat release, so that the oxidation reaction Falling into a vicious cycle, the sublimation of the active component molybdenum will be accelerated, shortening the life of the catalyst, and the reaction will be out of control, and the device will face the risk of explosion. Therefore, in order to achieve safe production and improve the economy of the process, this type of reaction requires the catalyst to have excellent Heat resistance

[0005] Patent CN105413702B mentions that the multilayer catalyst has excellent thermal conductivity, but in the actual preparation and application of the catalyst, there is a certain probability that the catalyst will have surface cracks, which will cause the heat resistance strength of the catalyst to decrease, the catalyst will be broken, and the bed pressure difference will increase. , resulting in an increase in side reactions, which need to be optimally controlled

In patent CN1461236A, the active component is coated on the inactive carrier ball to obtain a coated catalyst. The catalyst shows good conversion and selectivity, but the coated catalyst has high requirements for mechanical strength, especially wear resistance. , at the same time, the active component Mo element in the outer layer will inevitably be lost during the reaction process, resulting in a shortened catalyst life

Images