US EPA

6575286 

Journal Article 

HgCl2 Reduction under a Low-Temperature Selective Catalytic Reduction Atmosphere 

Jiang, S; Cai, L; Yang, J; Peng, H; Liu, Hui; Li, H; , 

2020 

Yes 

Energy and Fuels
ISSN: 0887-0624
EISSN: 1520-5029 

AMER CHEMICAL SOC 

WASHINGTON 

34 

2 

2417-2424 

English 

10.1021/acs.energyfuels.9b04284 

WOS:000518215400132 

http://://WOS:000518215400132
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Mercury chloride (HgCl2) is considered as the dominant form of mercury in coal combustion flue gas. Abundant studies were conducted to investigate how to stimulate the oxidation of elemental mercury (Hg-0) to HgCl2 over selective catalytic reduction (SCR) catalysts, which could be easily removed in a wet flue gas desulfurization system. However, the reverse reaction of Hg-0 oxidation, i.e., the reduction of HgCl2, was rarely studied. In this work, the entire mercury conversion process, including both Hg-0 oxidation and HgCl2 reduction, was investigated over a low-temperature SCR catalyst. Nitric oxide (NO) alone did not inhibit Hg-0 oxidation to HgCl2. However, NO with the assistance of ammonia (NH3) gas unexpectedly inhibited Hg-0 conversion, even in the presence of hydrogen chloride (HCl), which is generally recognized to be a great promotor of Hg-0 oxidation. The coexistence of NO and NH3 induced the reduction of HgCl2, which partly counteracted the forward Hg-0 oxidation reaction, thus leading to a lower observed Hg-0 oxidation efficiency. HgCl2 could not directly react with NO and NH3 to generate Hg-0 at low temperatures, while it could react with reduced species such as hydroxyl on the catalyst surface to produce Hg-0. This knowledge is of fundamental importance in accurately predicting Hg-0 conversion efficiency over SCR catalysts and developing efficient Hg-0 oxidation technologies. 

in-situ drifts; elemental mercury; flue-gas; simultaneous removal; cucl2/tio2 catalyst; no reduction; mixed oxides; oxidation; mechanism; Energy & Fuels; Engineering