title: Reaction pathway investigation on the selective catalytic reduction of NO with NH3 over Cu/SSZ-13 at low temperatures.
abstract: The mechanism of the selective catalytic reduction of NO with NH3 was studied using Cu/SSZ-13. The adspecies of NO and NH3 as well as the active intermediates were investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy and temperature-programmed surface reaction. The results revealed that three reactions were possible between adsorbed NH3 and NOx. NO2(-) could be generated by direct formation or NO3(-) reduction via NO. In a standard selective catalytic reduction (SCR) reaction, NO3(-) was hard to form, because NO2(-) was consumed by ammonia before it could be further oxidized to nitrates. Additionally, adsorbed NH3 on the Lewis acid site was more active than NH4(+). Thus, SCR mainly followed the reaction between Lewis acid site-adsorbed NH3 and directly formed NO2(-). Higher Cu loading could favor the formation of active Cu-NH3, Cu-NO2(-), and Cu-NO3(-), improving the SCR activity at low temperature.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, P. R. China.
authors.forename: Wenkang
authors.initials: W
authors.lastname: Su
authors.forename: Huazhen
authors.initials: H
authors.lastname: Chang
authors.forename: Yue
authors.initials: Y
authors.lastname: Peng
authors.forename: Chaozhi
authors.initials: C
authors.lastname: Zhang
authors.forename: Junhua
authors.initials: J
authors.lastname: Li
mesh_terms: D000327:Adsorption; D000397:Air Pollution / Q000517:prevention & control; D000641:Ammonia / Q000737:chemistry*; D002384:Catalysis; D003080:Cold Temperature; D003300:Copper / Q000737:chemistry*; D009566:Nitrates; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D017641:Zeolites / Q000737:chemistry*
chemical_list: D009566:Nitrates; D009589:Nitrogen Oxides; D017641:Zeolites; D000641:Ammonia; D003300:Copper