期刊
JOURNAL OF CATALYSIS
卷 306, 期 -, 页码 68-77出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2013.06.010
关键词
NH3-SCR; Cu/SAPO-34; Hydrothermal aging; Cu migration
资金
- GM Global RD
- Ministry of Education, China
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-06CH11357]
- Department of Energy
- MRCAT member institutions
In the present work, we report the migration of copper species in Cu/SAPO-34 during hydrothermal aging and its role in selective catalytic reduction (SCR) of NOx. Two Cu/SAPO-34 catalysts, prepared by ion-exchange and precipitation methods, were hydrothermally aged at 700 degrees C for 48 h and characterized in detail. The aged ion-exchanged catalyst exhibited little deterioration in activity; however, the catalytic activity of the precipitated catalyst, which showed inferior activity for the fresh sample, was markedly improved after hydrothermal treatment and became comparable to that of the ion-exchanged sample. A detailed characterization of the Cu species before, during, and after the hydrothermal treatment using a combination of experimental techniques clearly demonstrated that the copper species in the precipitated sample, which initially existed as CuO clusters on the external surface of SAPO-34, migrated to the ion-exchanged sites as isolated ions after aging. The change in copper oxidation states and coordination environment during the aging process was probed by in situ X-ray absorption spectroscopy, and a possible mechanism of Cu migration involving metallic Cu species was proposed. (C) 2013 Elsevier Inc. All rights reserved.
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