Yanke Yu,Mengqiao Geng,Jiahang Li,Jingjing Wang,Desheng Wei,Chi He
Commercial V 2 O 5 -WO 3 /TiO 2 (VWTi) catalysts used in NH 3 -SCR reaction with varied Zn loading were prepared and then effect of SO 2 on Zn-poisoned VWTi catalysts was investigated. Zn could cause the deactivation of VWTi catalysts. Nevertheless, the effect of SO 2 on Zn-poisoned VWTi catalysts varied with Zn loading. For Zn-poisoned catalyst with low content of Zn (1.0 wt.%, ZnL), SO 2 would promote the activity recovery of the catalyst. However, SO 2 had no influence on the Zn-poisoned catalyst with high Zn content (4.0 wt.%, ZnH). The catalyst was characterized by N 2 adsorption-desorption, XRD, XPS, SO 2 -TPD, NH 3 -TPD, H 2 -TPR and in situ DRIFTS. Tri-coordinated sulfate species were formed on ZnL sample in the presence of SO 2 , and the sulfate species could form new Brønsted acid sites, causing the recovery of activity. But ZnSO 4 was appeared and no Brønsted acid sites formed on ZnH sample under SO 2 , thus the activity of ZnH sample changed little.
Wenbo Jia,Yueyuan Wang,Shaohua Ling,Liren He,Binghe Chen,Songtao Liu,Chuanmin Chen,Yue Cao
Fast selective catalytic reduction (SCR) atmosphere can significantly improve the NOx removal activity of VWTi catalysts, while the catalytic performance and reaction pathway of Hg0 oxidation in a fast SCR atmosphere are still unclear. In this paper, the catalytic activity of simultaneous NOx removal and Hg0 oxidation over VWTi catalysts in a simulated fast SCR atmosphere was investigated for the first time. The results showed that VWTi catalysts possessed a wide NOx removal active temperature window and a high Hg0 oxidation activity in a fast SCR atmosphere. The X-ray photoelectron spectroscopy (XPS) and Hg temperature-programmed desorption (Hg-TPD) methods were used to investigate the Hg0 oxidation process over VWTi catalysts in a fast SCR atmosphere. Combined with the homogeneous Hg0 oxidation experiment results, two domination reaction routes of Hg0 oxidation over VWTi catalysts in a fast SCR atmosphere were proposed. One was that the adsorbed Hg0 could react with the surface active species to form HgO. The other reaction route was a gaseous homogeneous route that the gaseous Hg0 could be oxidized directly to Hg(NO3)2 by gaseous NO2. Particularly, the gaseous homogeneous Hg0 oxidation process could notably weaken the inhibition effect of NH3 on Hg0 oxidation, thus improving the Hg0 oxidation activity of VWTi catalysts in a fast SCR atmosphere.
Ming-Xiu Zhan,Long-Jie Ji,Yu-Feng Ma,Wang-Ruochen Chen,Sheng-Yong Lu
Catalytic oxidation is regarded an effective technique to control the emissions of chlorinated benzenes (CBzs) and polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) from waste incinerators . Among the numerous factors affecting the degradation efficiency of CBzs and PCDD/Fs, limited attention has been paid to the impact of hydrochloric acid (HCl) present in the flue gas . This study investigates how HCl affects the catalytic degradation of 1,2-dichlorbenzene (1,2-DCBz) at different reaction times and temperature regimes. The results showed that the removal efficiency of 1,2-DCBz, which was achieved by the V 2 O 5 /WO 3 -TiO 2 (VWTi) catalyst, decreased the largest by 10% in the presence of HCl. Furthermore, it was found that the increasing concentration of water vapor hindered the degradation efficiency of 1,2-DCBz. No relationship between the process temperature and the destruction efficiency of PCDD/Fs was observed in the presence of HCl. Potential increasing of the removal efficiency of 1,2-DCBz was confirmed by adding different amount of activated carbon (AC) in the presence of HCl.
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