Preparation method of low-temperature selective catalytic reduction (SCR) catalyst by removing NOx from flue gas

Abstract

The invention provides a preparation method of a selective catalytic reduction (SCR) catalyst Mn-Ce-M / TiO2 by removing NOx from flue gas, wherein M represents one or more of composite oxides, namely Fe, Co, Cu, Cr, Zr and Al, the molar ratio of the elements is Ti: Mn: Ce: M =1:(0.005-1):(0.005-1):(0-1). In the invention, an improved coprecipitation method is adopted, and an intermediate compound, namely titanium nitrate Ti(NO3)4 is taken as a precursor of TiO2, thus the influence of the other impurities in the precipitation process is overcome; by changing the dispersing homogeneous degree of MnOx and CeO2 on the surface of a carrier TiO2, the activity of the catalyst is improved and the temperature of the SCR reaction is reduced; by adjusting the preparation condition of the TiO2 precursor, the sulfur resistance and water resistance of the catalyst are improved completely; and by adding the elements, such as Fe, Co, Cu, Cr, Zr and Al and the like, the activity and resistance of the catalyst are further modified.

Description

technical field [0001] The invention relates to a method for preparing a low-temperature SCR catalyst for flue gas removal of NOx, especially a Mn-Ce / TiO-based catalyst with anti-sulfur dioxide and water performance 2 The preparation method of the low-temperature SCR catalyst of the system. Background technique [0002] Currently, using ammonia NH 3 As a reducing agent, selective catalytic reduction (SCR) NOx removal technology is the most widely used flue gas denitrification technology. NH 3 , NO and O 2 Oxidation-reduction reactions occur under the action of catalysts to generate N 2 and H 2 O. The catalyst used is mainly V 2 o 5 / TiO 2 series, it has very high catalytic activity, but it mainly has the following disadvantages in domestic applications: First, the reaction temperature is relatively high, and the general operating temperature is about 350 ° C. In order to meet the temperature requirements, the catalytic bed is generally arranged in the dust collector...

AI Technical Summary

Problems solved by technology

The catalyst used is mainly V 2 o 5 / TiO 2 series, it has very high catalytic activity, but it mainly has the following disadvantages in domestic applications: First, the reaction temperature is relatively high, and the general operating temperature is about 350 ° C. In order to meet the temperature requirements, the catalytic bed is generally arranged in the dust collector before, but on the one hand this arrangement will cause the SO of the catalyst 2 and alkali metal poisoning, as well as dust blockage, on the other hand, a larger space behind the furnace is required; second, the vanadium V in the active component is poisonous, which is harmful to the ecological environment and human health; third, the core technology of the catalyst has been adopted by foreign countries. Monopoly, domestic promotion and application need to pay high technology royalties, so the cost of engineering technology and catalysts is very high

The current impregnation method uses the direct loading of active components on nano-TiO 2 The catalyst is prepared by the method, and a certain denitrification activity is obtained, but the dispersion of the active components of the catalyst on the carrier is uneven, and it is easy to sinter and peel off. The catalyst is resistant to SO 2 The ability to intoxicate with water is not strong, and it is difficult to meet the requirements of popularization and application

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