Cerium-based denitrification catalyst and preparation method and application thereof

Abstract

A preparation method of a cerium-based denitrification catalyst includes the steps of dissolving Ce, Sn and Ti salts separately in deionized water, stirring until clarification, and mixing the three salt solutions to obtain a mixed salt solution; dropwise adding ammonia water solution as a precipitating agent into the mixed salt solution, stirring until PH of the mixed solution is 9-11 to generatewhite precipitate, stopping adding ammonia water, ad allowing to stand for aging; washing the white precipitate, filtering to obtain a catalyst precursor, and calcining the dried catalyst precursor to obtain Ce-Sn-TiOx composite oxide SCR (selective catalytic reduction) catalyst, with x ranges from 1 to 4. The SCR catalyst prepared via the preparation method herein has catalytic efficiency whichmay reach 90% and above in the reaction temperature range of 200-450 DEG C under the reaction condition of high space velocity (60000 h<-1>).

Description

technical field [0001] The invention belongs to the field of preparation technology of flue gas denitrification catalyst, and in particular relates to a cerium-based denitrification catalyst, a preparation method thereof, and an application of the catalyst. Background technique [0002] Nitrogen oxide (NOx) is a general term composed of nitrogen, oxygen and other compounds, and is one of the main pollutants in the atmosphere. 2 O, NO, NO 2 , N 2 o 5 , N 2 o 3 , NO 3 , N 2 o 4 , where NO and NO 2 The largest proportion. A large amount of NOx emitted into the air will cause various environmental problems, such as the formation of acid rain, photochemical smog, and the destruction of the ozone layer. my country's energy consumption is dominated by coal, so coal combustion has become the largest source of NOx, and its NOx emissions account for 67% of the country's total emissions. Among all coal-fired industries, thermal power plants have the largest NOx emissions. T...

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Problems solved by technology

[0004] At present, the denitrification efficiency is higher and the most mature application is V 2 o 5 / TiO 2 catalysts, but there are still many problems with such catalysts, such as N 2 The selectivity is low, the reaction temperature window is narrow, and it can only react in the temperature range of 300-400 °C, and the SO in the flue gas is easy to 2 Oxidation to SO 3 , causing catalyst deactivation, poisonous vanadium oxides, easy to cause secondary pollution to the environment and a series of problems

with V 2 o 5 / TiO 2 Catalyst based, by adding WO 3 、MoO 3 V 2 o 5 -WO 3 (MoO 3 ) / TiO 2 Although the catalyst has solved some problems, the improved catalyst still faces key problems such as low catalytic activity at low temperature, poor resistance to sulfur and water, etc.

[0005] At present, most domestic power plants use wet desulfurization, which makes the temperature of flue gas lower than 300°C after dust removal and desulfurization, which cannot reach the reaction temperature of vanadium-titanium catalysts, which easily leads to low denitrification efficiency and waste of catalysts. and many other disadvantages

And after desulfurization, some SO still remains in the flue gas 2 , will poison and deactivate the SCR catalyst at low temperature

In addition, the thermal power plants that have been built in my country do not reserve space for the denitrification device between the air preheater and the economizer, making the temperature of the flue gas lower after treatment

To achieve the use conditions of conventional catalysts, the flue gas must be heated, which increases the cost of flue gas treatment

As another major source of flue gas emissions, industrial combustion boilers and industrial furnaces have lower flue gas emission temperatures, which makes it difficult for existing SCR catalysts to meet the use requirements

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