title: Selective Catalytic Reduction over Cu/SSZ-13: Linking Homo- and Heterogeneous Catalysis.
abstract: Active centers in Cu/SSZ-13 selective catalytic reduction (SCR) catalysts have been recently identified as isolated Cu2+and [CuII(OH)]+ions. A redox reaction mechanism has also been established, where Cu ions cycle between CuIand CuIIoxidation states during SCR reaction. While the mechanism for the reduction half-cycle (CuII→ CuI) is reasonably well-understood, that for the oxidation half-cycle (CuI→ CuII) remains an unsettled debate. Herein we report detailed reaction kinetics on low-temperature standard NH3-SCR, supplemented by DFT calculations, as strong evidence that the low-temperature oxidation half-cycle occurs with the participation of two isolated CuIions via formation of a transient [CuI(NH3)2]+-O2-[CuI(NH3)2]+intermediate. The feasibility of this reaction mechanism is confirmed from DFT calculations, and the simulated energy barrier and rate constants are consistent with experimental findings. Significantly, the low-temperature standard SCR mechanism proposed here provides full consistency with low-temperature SCR kinetics.
authors.affiliation: Institute for Integrated Catalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Feng
authors.identifier: 0000-0002-8450-3419
authors.initials: F
authors.lastname: Gao
authors.affiliation: Institute for Integrated Catalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Donghai
authors.initials: D
authors.lastname: Mei
authors.affiliation: Institute for Integrated Catalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Yilin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Institute for Integrated Catalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: János
authors.initials: J
authors.lastname: Szanyi
authors.affiliation: Institute for Integrated Catalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.
authors.forename: Charles H F
authors.initials: CH
authors.lastname: Peden