Catalyst for selectively oxidizing methacrylaldehyde to prepare methacrylic acid and preparation and application methods thereof

Abstract

The invention discloses a catalyst for selectively oxidizing methacrylaldehyde to prepare methacrylic acid and preparation and application methods thereof. The catalyst for selectively oxidizing the methacrylaldehyde to prepare the methacrylic acid is composed of PaMobVcXxYyZz1HhOg1-Zz2Og2, wherein X is a combination of at least two from sodium, potassium, rubidium and cesium, Y is a mixture of one or at least two from calcium, magnesium, chromium, manganese, iron, cobalt, copper, nickel, zinc, aluminum, silicon, germanium, antimony, bismuth, lanthanum or cerium, and Z comprises titanium and / or zirconium. Compared with traditional phosphovanadomolybdate catalysts. The catalyst for selectively oxidizing the methacrylaldehyde to prepare the methacrylic acid can be higher in activity when applied to selectively oxidizing the methacrylaldehyde to prepare the methacrylic acid, and during the catalytic process, when the methacrylaldehyde converting rate is 90%, and the selectivity to the methacrylic acid can reach up to 93%, so that the catalyst for selectively oxidizing the methacrylaldehyde to prepare the methacrylic acid can meet the demands of practical industrial production.

Description

technical field [0001] The invention relates to the field of catalytic materials, in particular to a catalyst for preparing methacrylic acid through the selective oxidation of methacrolein, a preparation method and application thereof. Background technique [0002] In 1982, Japan Catalyst Chemical Corporation and Mitsubishi Rayon Corporation realized the industrialization of methyl methacrylate synthesis technology using isobutylene or tert-butanol as raw materials through two-step catalytic oxidation and one-step esterification. Among them, the oxidation of methacrolein to methacrylic acid is a key reaction of this process route, and the catalyst generally uses phosphomolybdic acid or phosphomolybdovanadate heteropolyacidate. [0003] CN1750878A discloses a catalyst for the gas-phase catalytic oxidation of methacrolein, isobutyraldehyde or isobutyric acid to prepare methacrylic acid and its preparation method and use. The catalyst uses heteropolyacid containing heteropolyac...

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[0003] CN1750878A discloses a catalyst for the gas-phase catalytic oxidation of methacrolein, isobutyraldehyde or isobutyric acid to prepare methacrylic acid and its preparation method and use. The catalyst uses heteropolyacid containing heteropolyacid Salt as active component, which contains Mo, V, P, Cu, Cs and NH 4 As the basic active component, the catalyst can use cesium weak salt or cesium hydroxide as the cesium raw material of the catalyst active component and ammonium acetate as the NH of the catalyst active component. 4 raw materials; the catalyst obtained by this scheme has low selectivity to methacrylic acid in the process of catalyzing the selective oxidation of methacrolein, more by-products, and high separation cost

[0004] CN104001542A discloses a heteropolyacid and oxide composite catalyst for the oxidation of methacrolein to methacrylic acid; the catalyst consists of phosphomolybdic acid and metal oxides (such as vanadium pentoxide, ferric oxide, copper oxide , nickel dioxide, manganese dioxide, cobalt oxide, titanium dioxide and zinc oxide) are mixed step by step in the liquid phase to form more active sites on the surface of heteropolyanions, and then add cesium to obtain; The conversion rate of acrolein is low, and the production cost is high

[0005] CN104001543A discloses a heteropolyacid catalyst for the oxidation of methacrolein to methacrylic acid and a preparation method thereof. The catalyst uses cesium phosphomolybdovanadate or ammonium phosphomolybdovanadate with strong thermal stability as the core, Ammonium phosphomolybdovanadate or cesium phosphomolybdovanadate is the second outer layer, and phosphomolybdovanadate with catalytic active sites is wrapped in the outermost layer; the conversion rate of methacrolein of the catalyst prepared by this scheme is low, And the preparation process adopts liquid phase reaction, the preparation process control is difficult

[0006] Although the above-mentioned documents provide some catalysts and preparation methods for the selective oxidation of methacrolein, there are still some problems that the preparation process adopts liquid phase reaction, and the parameter control is difficult. The conversion rate of aldehyde and the selectivity of methacrylic acid are insufficient, so it is still of great significance to develop a catalyst with higher conversion rate of methacrolein and the selectivity of methacrylic acid, and a preparation method with easy control of catalyst preparation process parameters

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