Composite catalyst for nitric oxide purification and application of composite catalyst

Abstract

The invention provides a composite catalyst for nitric oxide purification and application of the composite catalyst. The composite catalyst for nitric oxide purification, which is provided by the invention, comprises a low-temperature catalyst and a medium / high-temperature catalyst, wherein the active temperature of the low-temperature catalyst is within 100-250 DEG C; the active temperature of the medium / high-temperature catalyst is within 200-500 DEG C; the volume ratio of the low-temperature catalyst to the medium / high-temperature catalyst is (1:5)-(5:1). As advantages of the low-temperature catalyst and the medium / high-temperature catalyst with excellent properties are combined, the composite catalyst has a wide temperature range, excellent low-temperature activity and N2 generation selectivity, and is high in NOx conversion rate and applicable to diesel engine tail gas NOx control and fixed source fume denitration.

Description

technical field [0001] The invention belongs to the technical field of air pollution purification, and relates to a combined catalyst for purifying nitrogen oxides and its application. Background technique [0002] Motor vehicle exhaust is an important source of air pollution in my country and an important cause of haze and photochemical smog. The urgency of my country's motor vehicle pollution prevention and control has become increasingly prominent, and the NO in the exhaust of diesel vehicles (especially heavy-duty diesel vehicles) x Control is an urgent problem to be solved. According to the "2016 China Motor Vehicle Environmental Management Annual Report" issued by the Ministry of Environmental Protection, diesel vehicles, which only account for 12.6% of my country's car ownership, emit NO x It accounts for 69% of total vehicle emissions. Among them, although diesel-fueled heavy-duty trucks account for only 3.3% of the vehicle population, their NO x Emissions account...

AI Technical Summary

Problems solved by technology

Therefore, since NH 3 The over-oxidation of the medium and high temperature will cause a significant decrease in the conversion efficiency of NO, and even the phenomenon that the NO concentration is higher than the initial concentration. 2 The massive generation of O (NH 2 →NH+H, NH+NO→N 2 O+H) resulting in N 2 Significantly lower selectivity

[0005] On the other hand, many excellent NH 3 -SCR catalysts have excellent catalytic activity in the medium and high temperature range, but the low temperature activity needs to be further improved

For example, the Ce-Ti oxide catalyst we developed earlier has a wide active temperature window and can efficiently remove NO in a high space velocity environment. x , but its low-temperature activity is significantly lower than that of Mn-based oxide catalysts

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