Catalyst, preparation method and application thereof

Abstract

The invention relates to a catalyst, a preparation method and application thereof. The catalyst has composition shown as the formula in the specification, wherein D is at least one of copper, magnesium, manganese, antimony and zinc, E is at least one of tungsten, silicon, nickel, palladium, iron and lead; Z is SiC, MoO3, WO3, TiO2 or ZrO2, y / x is 11.1-50%, a is 0.1-3, b is 0.01-5, c is 0.01-5, d is 0.01-3, e is 0.01-2, and f is the atom ratio of oxygen for meeting the valency. The method comprises: (i) preparing a solution A from compounds of molybdenum, phosphorus and vanadium, preparing a solution B from potassium and a D-containing compound, and preparing a solution C from an E-containing compound; (ii) mixing the solution A, the solution B and the solution C at a temperature ranging from -5 to 10DEG C; (iii) conducting pre-roasting; (iv) adding graphite powder and a dilution heat conduction agent, controlling the weight ratio y / x of the dilution heat conduction agent to a catalyst precursor at 11.1-50%; and (V) performing roasting. x(Mo12PaKbVcDdEeOf) / yZ.

Description

technical field [0001] The invention relates to a catalyst for synthesizing methacrylic acid (MAA) from methacrolein (MAL) through an oxidation reaction. The catalyst can produce methacrylic acid with high conversion rate and high selectivity at relatively low reaction temperature. The invention also relates to a method for preparing the catalyst and the use of the catalyst in the synthesis of methacrylic acid (MAA) from methacrolein (MAL) by oxidation. Background technique [0002] The production of methacrylic acid by gas-phase oxidation of methacrolein with a heteropolyacid catalyst is currently the most widely used method for producing methacrylic acid in industry. In such a process, the yield of methacrylic acid is mainly affected by the performance of the heteropolyacid catalyst used, most of which contain phosphorus and molybdenum as main components, with heteropolyacid and / or Salt structure, they have low reactivity, low selectivity for methacrylic acid and short li...

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Problems solved by technology

[0003] Chinese patent CN1270824C proposes that coating catalysts are used to increase the effective utilization of catalyst active components, and the purpose of improving catalyst selectivity is achieved by increasing the thermal conductivity of the catalyst or quickly removing the heat of reaction due to the dilution effect of the inactive carrier. However, it is difficult to obtain a catalyst with high mechanical strength, and the reaction temperature of the catalyst is too high, which is not good for the catalyst life

[0004] U.S. Patent No. 5,422,326 proposes to control the pore size distribution of the catalyst by adding an organic polymer compound with an average particle size of 0.01 to 10 microns during the molding process to improve the selectivity of the catalyst. However, the high reaction temperature of the catalyst is not conducive to prolonging the catalyst. life

[0005] Chinese patent CN1874842A proposes that a high-performance catalyst can be obtained by using the following procedures: the procedure of preparing a solution or slurry (I solution) containing molybdenum, phosphorus and vanadium; the procedure of preparing a solution or slurry (II solution) containing ammonium radicals; Either solution (PR liquid) of liquid I or liquid II is put into the tank (tank A), and it has a continuous liquid level with an area of ​​0.01 to 10% relative to the entire area of ​​the liquid surface of the PR liquid loaded into tank A. In the area, another above-mentioned solution (LA solution) is put into the process of preparing the mixed liquid of liquid I and liquid II; the catalyst is obtained by drying and roasting, but the catalyst also has the disadvantage of high reaction temperature

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