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NH 3 Oxidation Mechanism over Cu/SAPO‐34 Catalysts Prepared by Different Methods
Author(s) -
Yu Tie,
Wang Jun,
Huang Yu,
Shen Meiqing,
Li Wei,
Wang Jianqiang
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402048
Subject(s) - catalysis , chemistry , electron paramagnetic resonance , redox , diffuse reflectance infrared fourier transform , reaction mechanism , scanning electron microscope , fourier transform infrared spectroscopy , temperature programmed reduction , inorganic chemistry , infrared spectroscopy , copper , nuclear chemistry , selective catalytic reduction , analytical chemistry (journal) , materials science , photocatalysis , nuclear magnetic resonance , chemical engineering , organic chemistry , physics , engineering , composite material
NH 3 oxidation mechanism and its inhibition effect on the selective catalytic reduction of NO x by NH 3 (NH 3 –SCR) reaction over two series of Cu/SAPO‐34 catalysts were studied. It was found that the different NO conversions were induced by the diverse NH 3 oxidation degree. X‐ray diffraction, scanning electron microscopy, H 2 temperature‐programmed reduction (H 2 –TPR), and CO diffuse reflectance infrared Fourier transform spectroscopy (CO–DRIFTS) analyses were conducted to estimate the Cu species distribution. The TPR results showed that the CuO species was dominant in impregnated Cu/SAPO‐34 samples, and the ion‐exchanged Cu/SAPO‐34 samples contained more isolated Cu 2+ species. Furthermore, H 2 –TPR, electron paramagnetic resonance, and CO–DRIFTS analyses were utilized to quantify the CuO, Cu 2+ , and Cu + species. The results together with the kinetic results revealed the CuO is the active site for NH 3 oxidation, and the NH 3 oxidation over Cu/SAPO‐34 sample consists two steps: (a) NO production; (b) further NO consumption by adsorbed NH 3 species on Cu 2+ sites. Finally, the inhibition of NH 3 oxidation on NH 3 –SCR activity was explained and the NO conversion at high temperature was related to the Cu 2+ /CuO ratio in Cu/SAPO‐34 sample.