Manganese-zirconium dual metal modified selective catalytic reduction catalyst for molecular sieve type diesel engine

Abstract

The invention discloses a manganese-zirconium dual metal modified selective catalytic reduction catalyst for a molecular sieve type diesel engine. In the catalyst, manganese and zirconium elements enter a molecular sieve by a liquid ion exchange-immersion method; by taking the total weight of the modified powdered catalyst as reference, the manganese element accounts for 4.5 to 7.5 percent, and the zirconium element accounts for 4.5 to 15 percent; by taking the total weight of a supported catalyst as reference, a coating accounts for 5 to 15 percent; urea or ammonia is adopted as a reducing agent to remove NOx in exhaust gas of the diesel engine by virtue of selective catalytic reduction reaction; the novel SCR (selective catalytic reduction) catalyst for the diesel vehicle is prepared from non-toxic molecular sieve and low-toxic manganese and zirconium elements, so that the toxicity of the catalyst to a human body is reduced; and simultaneously a high-activity temperature window of the catalyst in the SCR reaction of the diesel vehicle is enlarged. According to the modification method, the supporting capacity is improved, the supporting proportion is more flexible and adjustable,and further optimization of the catalyst performance is facilitated.

Description

technical field [0001] The invention belongs to a purification catalyst for diesel engines, in particular to a molecular sieve type catalyst for diesel engines modified by manganese and zirconium bimetals. Background technique [0002] At present, the exhaust emission of vehicle diesel engine is one of the important pollution sources, and the nitrogen oxide (NOx) and particulate matter (PM) emitted by it seriously endanger human health. Since it is difficult to reduce NOx and PM emissions at the same time by improving the combustion in the cylinder, the exhaust after-treatment technology has become an inevitable choice for diesel engine emission control. The Selective Catalytic Reduction (SCR) technology using urea or ammonia as the reducing agent has extremely high NOx purification efficiency, and through matching and optimizing combustion improvement measures, it can also reduce PM emissions and engine fuel consumption at the same time. One of the promising efficient post...

AI Technical Summary

Problems solved by technology

The current commercialized SCR catalysts are mainly based on V 2 o 5 The supported catalyst as the main catalyst has a small effective temperature window, especially the minimum effective temperature is around 300°C, which is difficult to meet the actual requirements for low-temperature activity of SCR catalysts for diesel vehicles operating on Chinese urban roads

At the same time V 2 o 5 It is a highly toxic substance. Because the catalyst will inevitably be lost during use, the vanadium-based catalyst is harmful to human health.

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