Molecular sieve catalyst modified by rare earth metal and preparation method of molecular sieve catalyst

Abstract

The invention belongs to the technical fields of material chemistry and catalytic chemistry, and particularly relates to a molecular sieve catalyst modified by rare earth metal and a preparation method of the molecular sieve catalyst. The catalyst comprises a porous ceramic carrier and a molecular sieve catalyst coating layer which coats the carrier and is modified by the rare earth metal. The molecular sieve catalyst is characterized in that the coating weight of the molecular sieve catalyst coating layer is 30-400 g / L, and the weight ratio of molecular sieves to the rare earth metal to active components in the molecular sieve catalyst is 1:(0.1 wt.%-10 wt.%):(0.1 wt.%-10 wt.%), wherein the rare earth metal is one or more of Ce, La, Pr, Y, Sm, Yb and Nd. According to the catalyst and thepreparation method, through two modes of control over key parameters in the ion exchange process and hydrothermal calcination for promoting migration of rare earth metal ions, the content of the rareearth metal in a molecular sieve cage is adjusted, so that defect parts of a silicon-aluminum molecular sieve are filled with a proper number of rare earth metal ions, the structural stability of themolecular sieve catalyst can be significantly improved under the high-temperature hydrothermal condition, and the molecular sieve catalyst has a wide application prospect in the aspect of denitrationfor tail gas of diesels.

Description

technical field [0001] The invention belongs to the technical fields of material chemistry and catalytic chemistry, and in particular relates to a rare earth metal modified molecular sieve catalyst and a preparation method thereof. Background technique [0002] Metal-based molecular sieve catalysts have the advantages of microporous structure, non-toxicity, and SCR catalytic activity much higher than vanadium-titanium-based catalysts. 3 - Research hotspots of SCR denitrification. In the prior art, mostly by reducing the SiO of the molecular sieve catalyst 2 / Al 2 o 3 To obtain more active metal ion exchange sites and The acidic site further improves the SCR denitrification activity and ammonia storage capacity of the catalyst at low temperature (<200°C). [0003] However, the temperature of the DPF in the national VI diesel engine exhaust after-treatment system is as high as 600-800°C during active regeneration, and the high-temperature water vapor generated will ca...

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Problems solved by technology

[0003] However, the temperature of the DPF in the national VI diesel engine exhaust after-treatment system is as high as 600-800°C during active regeneration, and the high-temperature water vapor generated will cause the dealumination of the molecular sieve, thereby destroying the stability of the molecular sieve network structure [1]

At the same time, under the condition of high-temperature water vapor, the metal cations in the catalytic active center migrate and aggregate to form low-activity metal oxides, resulting in NO X The removal efficiency dropped sharply

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