title: Insight into the mechanism of selective catalytic reduction of NO(x) by propene over the Cu/Ti(0.7)Zr(0.3)O2 catalyst by Fourier transform infrared spectroscopy and density functional theory calculations.
abstract: The mechanism of selective catalytic reduction of NOx by propene (C3H6-SCR) over the Cu/Ti0.7Zr0.3O2 catalyst was studied by in situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations. Especially, the formation and transformation of cyanide (-CN species) during the reaction was discussed. According to FTIR results, the excellent performance of the Cu/Ti0.7Zr0.3O2 catalyst in C3H6-SCR was attributed to the coexistence of two parallel pathways to produce N2 by the isocyanate (-NCO species) and -CN species intermediates. Besides the hydrolysis of the -NCO species, the reaction between the -CN species and nitrates and/or NO2 was also a crucial pathway for the NO reduction. On the basis of the DFT calculations on the energy of possible intermediates and transition states at the B3LYP/6-311 G (d, p) level of theory, the reaction channel of -CN species in the SCR reaction was identified and the role of -CN species as a crucial intermediate to generate N2 was also confirmed from the thermodynamics view. In combination of the FTIR and DFT results, a modified mechanism with two parallel pathways to produce N2 by the reaction of -NCO and -CN species over the Cu/Ti0.7Zr0.3O2 catalyst was proposed.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Xinyong
authors.initials: X
authors.lastname: Li
authors.forename: Qidong
authors.initials: Q
authors.lastname: Zhao
authors.forename: Ce
authors.initials: C
authors.lastname: Hao
authors.forename: Dongke
authors.initials: D
authors.lastname: Zhang
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D008962:Models, Theoretical; D009589:Nitrogen Oxides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000475:Alkenes; D009589:Nitrogen Oxides; D003300:Copper; C013658:propylene; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide