Storage reduction catalyst used for removing nitrogen oxide in lean burn engine tail gas and preparation method

Abstract

The invention relates to a storage reduction catalyst used for removing nitrogen oxide in lean burn engine tail gas and a preparation method. The preparation method comprises the following steps of: with soluble cerium salt and zirconium salt as raw materials, alkali as coprecipitator and polyethylene glycol as thickening agent, preparing a cerium zirconium powder carrier according to the atom ratio of Ce to Zr of (6-8):(4-2); with soluble barium salt as a raw material, loading the barium salt onto the cerium zirconium powder carrier by adopting an isovolumetric method, wherein BaO accounts for 20-40% of the mass of the catalyst; then loading one or two precious metals of Pt and Pd accounting for 1.0-3.0% of the mass of the catalyst by adopting the isovolumetric method, thus a sample I is obtained; with Al2O3 as a carrier, loading one or two precious metals of Rh and Pd accounting for 0.5-2.0% of the mass of the catalyst by adopting the isovolumetric method, thus a sample II is obtained; and mechanically mixing the sample I and the sample II according to the mass ratio of (1-3):1, thus the nitrogen oxide storage reduction catalyst comprising 50-75% of ((Pt,Pd) / BaO / CexZr(1-x)O2) and 50-25% of ((Rh,Pd) / Al2O3) is obtained, wherein NOx conversion rate of the catalyst can reach more than 80%. After treatment in presence of high-temperature water vapour or SO2 is carried out, the nitrogen oxide storage reduction activity is maintained to be more than 80%.

Description

technical field [0001] The invention relates to a nitrogen oxide storage and reduction catalyst for removing lean-burn engine exhaust gas and a preparation method thereof, more specifically, to a nitrogen oxide storage and reduction catalyst for removing lean-burn engine exhaust gas and its preparation method. Preparation. Background technique [0002] According to statistics, in 2010 China's auto production and sales exceeded 18 million. With the continuous development of the economic level, the production and sales of automobiles will maintain a continuous growth momentum. The rapid development of the automobile industry has also brought problems of energy shortage and environmental pollution. Against this backdrop, lean-burn technology emerged as the times require. Lean combustion technology is an effective measure to reduce vehicle exhaust emissions and reduce fuel consumption. The air-fuel ratio of a lean-burn engine works stably is 23-27, and the oxygen concentrati...

AI Technical Summary

Problems solved by technology

The main problems of nitrogen oxide storage and reduction catalysts include: narrow activity temperature window, resistance to sulfur poisoning, poor hydrothermal aging ability, etc.

[0005] At present, there are no domestic patents on the preparation method of nitrogen oxide storage and reduction catalysts. Therefore, it is particularly necessary to develop a catalyst preparation method with a wide active temperature window and strong resistance to sulfur poisoning and hydrothermal aging.