Propene Surface Species and Their Role in NO Reduction over Cu-ZSM-5 in the Excess of Oxygen
Статья (Full article),
Kinetics and Catalysis
, E-ISSN: 1608-3210
Институт катализа им. Г.К. Борескова СО РАН
Институт химической физики им. Н.Н. Семенова РАН
The nature and reactivity of surface complexes under the conditions of NO reduction by propene over Cu-ZSM-5 in the excess of oxygen are studied in situ by IR spectroscopy. The pi- and pi-allyl complexes are formed during the interaction of C3H6 or C3H6 + O-2 With the zeolite surface at low temperatures, whereas coke is formed at higher temperatures. Complexes with organic nitro compounds are observed in the presence of NO at relatively low temperatures, and nitrito complexes are found under the reaction conditions (300 degrees C). NO reduction by propene over Cu-ZSM-5 in the excess of O-2 occurs via two routes. One involves the formation of coke on the surface followed by the interaction of coke with NO to yield the reaction products. In this process, coke by itself serves is a reducing agent. In this reaction, copper ions increase the rate of the coke formation and change the ratio between the amounts of "soft" and "hard" coke. The other route involves the reaction between propene and the Cu2+-O-N=O complex formed on copper ions followed by the formation of reaction products. This process is analogous to that observed earlier for NOx, reduction by propane in these systems.