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Mechanistic Insight into Selective Catalytic Combustion of HCN over Cu-BEA: Influence of Different Active Center Structures

Abstract

HCN being of one kind of highly toxic N-containing volatile organic compounds (VOCs) exerts great threat to the human living environment. Selective catalytic combustion of HCN (HCN-SCC) over metal modified zeolite catalysts has attracted great attentions due to related high efficiency and excellent N2 selectivity. In the present work, three types of 24T-Cu-BEA models with different active centers of single [Cu]+; double [Cu]+; and [Cu-O-Cu]2+ were constructed for HCN-SCC mechanism simulations based on density functional theory (DFT). The DFT simulation results revealed that the HCN-SCC would follow an oxidation mechanism over double [Cu]+ through an intermediate of NCO, wherein the synergistic effects of double [Cu]+ active centers were clearly observed resulting in a greatly low energy barrier (1.6 kcal mol-1) during HCN oxidation into NCO. However, an oxidation mechanism (HCN oxidation into NH radical and CO2 through intermediate of HNCO) combining with a hydrolysis mechanism (NH radical hydrolysis into NH3) occurred over single [Cu]+ and [Cu-O-Cu]2+, wherein NH2 hydrolysis into NH3 step was regarded as the rate determining step with the respective energy barrier of 72.3 and 74.3 kcal mol-1. Finally, Mulliken charge transfer (CT) analysis was conducted, based on which the electric properties of different active centers were well illustrated.

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Publication details

The article was received on 09 Jul 2017, accepted on 08 Aug 2017 and first published on 08 Aug 2017


Article type: Paper
DOI: 10.1039/C7CP04604A
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Mechanistic Insight into Selective Catalytic Combustion of HCN over Cu-BEA: Influence of Different Active Center Structures

    N. Liu, X. Yuan, R. Zhang, Y. Li and B. Chen, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP04604A

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