Ternary Metal Modified Molecular Sieve Selective Catalytic Reduction Catalyst for Lean Burn Engine

Abstract

The invention discloses a ternary metal modified molecular sieve type lean burn engine selective catalytic reduction catalyst. The catalyst adopts a Cu-Ce-Zr ternary metal modified molecular sieve as an active component, gamma-Al2O3 as a coat matrix and cordierite honeycomb ceramic as a supported catalyst carrier, and the ratio of the mass sum of copper oxide, cerium oxide and zirconia to the mass of the ZSM-5 molecular sieve is 10.9-23.7% / 89.1-76.3%. A preparation technology of the catalyst comprises a step of determining the consumption amount of a catalyst raw material, a step of preparing the active component, and a step of preparing and supporting a coat slurry. The catalyst removes NOx in the exhaust of a lean burn engine through the selective catalytic reduction by adopting urea or ammonia gas as a reducing agent. The cerium oxide can improve the low temperature catalytic activity of the catalyst, and zirconia forms a solid solution together with the cerium oxide to improve the heat ageing resistance of the cerium oxide. The catalyst which contains no toxic materials avoids the harms of V2O5 catalysts to the health of humans.

Description

technical field [0001] The invention belongs to engine nitrogen oxide purification catalysts, in particular to a catalyst for purifying nitrogen oxides in lean-burn engine tail gas through selective catalytic reduction reaction and a preparation method thereof. Background technique [0002] Exhaust emissions from motor vehicles are atmospheric nitrogen oxides (NO X ), and NOx is not only harmful to human health, but also the precursor of acid rain and photochemical smog, which can be transformed into more harmful substances in the environment. Therefore, countries around the world have issued increasingly strict emission regulations. NOx emissions from motor vehicles. To this end, engine manufacturers have developed a variety of NOx purification technologies, among which technologies such as three-way catalytic converters have been widely used in gasoline engines. However, there is a certain amount of oxygen in the exhaust of lean-burn engines such as diesel engines and ga...

AI Technical Summary

Problems solved by technology

The copper-modified ZSM-5 molecular sieve catalyst has good SCR catalytic performance, but its low-temperature activity cannot meet the low-temperature activity requirements of lean-burn engine vehicles in urban areas for SCR catalysts

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