Catalyst for selectively reducing NOx by ammonia with high thermal stability and preparation method thereof

Abstract

The invention relates to a manganese-based composite oxide catalyst for selectively reducing NOx by ammonia with high thermal stability and high low-temperature activity and a preparation method thereof. The catalyst can be applied to purification of NOx in flue gas from factories and vehicle tail gas. The catalyst is prepared with manganese oxide as an active component and samarium and other transit metals as cocatalysts, thus forming the ternary metal composite oxide catalyst. The catalyst is used for a reaction of selectively catalytically reducing NOx by ammonia and has very wide temperature window at a low temperature. After being roasted at 500-650 DEG C, the catalyst can reach more than 80% in NOx removal rate in a temperature range of 50 to 300 DEG C. The catalyst also has strong anti-water and anti-sulfur-poisoning capability. The preparation method is simple and low-cost, and has excellent application prospect.

Description

technical field [0001] The invention relates to a preparation method and application of an ammonia selective catalytic reduction catalyst used for removing nitrogen oxides in power plant boilers, various industrial furnaces and motor vehicle tail gases, and belongs to the field of environmental pollution control. Background technique [0002] At present, my country's energy structure is dominated by coal. According to statistics, thermal power installed capacity accounts for more than 74% of my country's installed power generation capacity. pollute. Among various flue gas denitrification technologies such as selective catalytic reduction, selective non-catalytic reduction, and nitrogen oxide storage and reduction, the most widely used and most mature technology is the selective catalytic reduction method, which has high efficiency and great impact on boilers. The advantages of little modification of the original equipment, etc., the technology has achieved large-scale indust...

AI Technical Summary

Problems solved by technology

Patent CN10449245A reports a kind of MnO X and different contents of rare earth oxides, although the catalyst exhibits good low-temperature activity and water and sulfur resistance, but the thermal stability is poor. -1 Under the condition of space velocity, the temperature window where the NOx conversion rate is higher than 80% is only 180-280°C

[0005] Although the catalysts listed above have good low-temperature catalytic activity, the ammonia-selective nitrogen oxide reduction activity of the catalyst will be significantly reduced after the catalyst is roasted at high temperature during the preparation process, resulting in narrowing of the temperature window. Poor stability

In the actual application process, due to the instability of the actual working conditions, there are certain fluctuations in the temperature of flue gas and diesel vehicle exhaust, which will generate instantaneous high temperature, so the catalyst is required to have a certain high temperature stability