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Method for oxidizing elemental mercury by improving gas selective catalytic reduction (SCR) denitration processing system

A treatment system and SCR catalyst technology, applied in chemical instruments and methods, separation methods, dispersed particle separation, etc., can solve the problem of low mercury oxidation efficiency and achieve the effect of improving the removal rate

Inactive Publication Date: 2016-02-03
HEBEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The methods to realize the oxidation of elemental mercury to oxidized mercury include advanced oxidation methods such as oxidant method, photocatalysis and plasma discharge. Traditional SCR catalysts use V 2 o 5 -WO 3 / TiO 2 Medium-temperature catalyst, the catalyst exhibits high denitrification efficiency at 300-400°C, but the catalyst has a low mercury oxidation efficiency in this temperature range, generally at a mercury oxidation efficiency of 20%-40%

Method used

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Examples

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Effect test

Embodiment 1

[0012] A method for oxidizing elemental mercury by improving the flue gas SCR denitrification treatment system. The traditional SCR catalyst layer is arranged in front of the mercury oxidation catalyst, and then a layer of modified SCR catalyst is arranged as the mercury oxidation catalyst layer. In the traditional SCR catalytic system Inject NH 3 , NH 3 The molar ratio to NO is 0.6:1. The preparation method of the modified SCR catalyst is: adding transition metal oxides during the preparation of the SCR catalyst to modify it, that is, at V 2 o 5 -WO 3 / TiO 2 In the preparation of the SCR catalyst, after adding V 2 o 5 and WO 3 At the same time as the precursor, cerium nitrate was also added, and the mass of cerium nitrate added was 8% of the total amount of the catalyst based on Ce, and the removal efficiency of NO in flue gas was 80% at a temperature of 300-400 °C, and the oxidation efficiency of mercury 85%.

Embodiment 2

[0014] A method for oxidizing elemental mercury by improving the flue gas SCR denitrification treatment system. Before the traditional 4-layer SCR catalyst layer is arranged on the mercury oxidation catalyst, inject NH into the traditional SCR catalytic system 3 , NH 3 The molar ratio to NO is 1:1, and then two layers of modified SCR catalysts are arranged as the mercury oxidation catalytic layer. The preparation method of the modified SCR catalyst is: adding transition metal oxides during the preparation of the SCR catalyst to modify it. ie at V 2 o 5 -WO 3 / TiO 2 In the preparation of the SCR catalyst, after adding V 2 o 5 and WO 3 At the same time as the precursor, cerium nitrate was also added, and the mass of cerium nitrate added was 2% of the total amount of the catalyst based on Ce. The removal efficiency of NO in the flue gas was 95% at a temperature of 300-400 °C, and the oxidation efficiency of mercury was 95%. was 73%.

Embodiment 3

[0016] A method for oxidizing elemental mercury by improving the flue gas SCR denitrification treatment system. Before the traditional 3-layer SCR catalyst layer is arranged on the mercury oxidation catalyst, inject NH into the traditional SCR catalytic system 3 , NH 3 The molar ratio to NO is 0.9:1, and then a layer of modified SCR catalyst is arranged. The preparation method of the modified SCR catalyst is: adding transition metal oxides during the preparation of the SCR catalyst to modify it, that is, at V 2 o 5 -WO 3 / TiO 2 In the preparation of the SCR catalyst, after adding V 2 o 5 and WO 3 At the same time as the precursor, cerium nitrate was also added. The added mass of cerium nitrate was calculated as 4% of the total amount of catalyst based on Ce. The removal efficiency of NO in the flue gas was 85% at a temperature of 300-400 ° C. The oxidation of mercury The efficiency is 81%.

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Abstract

The invention discloses a method for oxidizing elemental mercury by improving a gas selective catalytic reduction (SCR) denitration processing system, wherein a traditional SCR catalyst layer is distributed in front of a mercury oxidation catalyst, and 1-2 layers of modified SCR catalysts are further distributed. A method for preparing a modified SCR catalyst is that predecessors of V2O5 and WO3 are added in the preparation of a SCR catalyst of V2O5-WO3 / TiO2, and cerous nitrate, cupric nitrate or cobalt nitrate is further added at the same time, and the oxidation efficiency of mercury in gas is above 80%. The method for oxidizing the elemental mercury by improving the gas SCR denitration processing system has the advantages that the method for oxidizing the elemental mercury by improving the gas SCR denitration processing system does not need to improve equipment based on an original gas SCR denitration processing system, does not need to use additional additives, does not need to be further provided with mercury removal equipment, and achieves to effectively denitration and mercury oxidation by utilizing the SCR catalyst and the modified SCR catalyst. Simultaneously, the method for oxidizing the elemental mercury by improving the gas SCR denitration processing system prevents the influence of NH3 to mercury oxidation by reasonably arranging the SCR catalyst and the modified SCR catalyst, thereby improving mercury discharge efficiency.

Description

technical field [0001] The invention relates to the improvement of a flue gas SCR denitration treatment system, in particular to a method for oxidizing elemental mercury by improving the flue gas SCR denitration treatment system. Background technique [0002] With the increasingly stringent air quality standards, mercury pollution in coal-fired flue gas has attracted more and more attention. There are three main forms of mercury in flue gas: particulate mercury (Hg p ), oxidized mercury (Hg 2+ ), elemental mercury (Hg 0 ). Particulate mercury can be captured by dust removal equipment, oxidized mercury can be washed and removed by desulfurization slurry in the wet desulfurization system, and most of the mercury in the flue gas exists in the form of elemental mercury, which is volatile and insoluble Difficult to remove in water. [0003] At present, the relatively mature mercury removal technology in flue gas that has been applied in industry is activated carbon adsorption...

Claims

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Application Information

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IPC IPC(8): B01D53/86B01D53/56B01D53/64B01J23/30B01J23/888
Inventor 沈伯雄朱少文池桂龙
Owner HEBEI UNIV OF TECH
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