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The remarkable promotional effect of SO 2 on Pb-poisoned V 2 O 5 -WO 3 /TiO 2 catalysts: An in-depth experimental and theoretical study

Yu, Yanke, Miao, Jifa, He, Chi, Chen, Jinsheng, Li, Can and Douthwaite, Mark 2018. The remarkable promotional effect of SO 2 on Pb-poisoned V 2 O 5 -WO 3 /TiO 2 catalysts: An in-depth experimental and theoretical study. Chemical Engineering Journal 338 , pp. 191-201. 10.1016/j.cej.2018.01.031

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Abstract

Currently, Pb poisoning of heterogeneous catalysts is considered to be a key area of interest in research involved with industrial NOx reduction. As such, a series of Pb-poisoned V2O5-WO3/TiO2 catalysts were prepared by a wet impregnation method and the influence of SO2 on the performance of these poisoned catalysts for NOx reduction was assessed both experimentally and using theoretical calculations. As expected, the incorporation of Pb in these materials resulted in a significant reduction in their catalytic performance. The conversion of NOx over the Pb-V2O5-WO3/TiO2 catalyst increased from approximately 50% to 90% in presence of SO2 (2000 ppm) at 350 °C. It was postulated that in the absence of SO2, Pb reacts with surface V-OH species, which ultimately results in the destruction of Brønsted acid sites; considered to be crucial for the catalytic conversion of NOx. In the presence of SO2 however, enhanced catalytic activity was observed which was suggested to be a result of the formation of additional Brønsted sites (S-OH) via a surface bidentate sulfate intermediate species. The formation of these species was attributed to the interaction of Pb with SO2 and O2 on the surface of the catalyst. Density functional theory (DFT) calculations based on a monolayer V model on TiO2 (0 0 1) showed that SO2 absorbed selectively onto Pb sites rather than V or Ti oxides. It was subsequently determined that NH3 absorption proceeds through the formation of Pb-N species with Pb atom and H-O with SO2. We believe that the present work provides new insights into the design and application of SCR catalysts with specific relevance for application in flue gas streams which contain high quantities of Pb content.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Chemistry
Cardiff Catalysis Institute (CCI)
Publisher: Elsevier
ISSN: 1385-8947
Date of First Compliant Deposit: 10 April 2018
Date of Acceptance: 4 January 2018
Last Modified: 29 Jun 2019 15:23
URI: http://orca-mwe.cf.ac.uk/id/eprint/110605

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