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Title: Kinetic isotopic effects in oxidative dehydrogenation of propane on vanadium oxide catalysts

Abstract

Kinetic isotopic effects (KIEs) for oxidative dehydrogenation of propane were measured on 10 wt% V{sub 2}O{sub 5}/ZrO{sub 2}. Normal KIEs were obtained using CH{sub 3}CH{sub 2}CH{sub 3} and CD{sub 3}CD{sub 2}CD{sub 3} as reactants for primary dehydrogenation (2.8) and combustion (1.9) of propane and for secondary combustion of propene (2.6), suggesting that in all cases C-H bond dissociation is a kinetically relevant step. CH{sub 3}CH{sub 2}CH{sub 3} and CH{sub 3}CD{sub 2}CH{sub 3} reactants led to normal KIEs for dehydrogenation (2.7) and combustion (1.8) of propane, but to a very small KIE (1.1) for propene combustion. These results show that the methylene C-H bond is activated in the rate-determining steps for propane dehydrogenation and combustion reactions. The rate-determining step in secondary propene combustion involves the allylic C-H bond. In each reaction, the weakest C-H bond in the reactant is cleaved in the initial C-H bond activation step. The measured propane oxidative dehydrogenation KIEs are in agreement with theoretical estimates using a sequence of elementary steps, reaction rate expression, and transition state theory. The much smaller KIE for propane oxidative dehydrogenation (2.8) than the maximum KIE (6) expected for propane thermal dehydrogenation indicates the participation of lattice oxygen. The different KIE valuesmore » for propane primary dehydrogenation and combustion suggest that these two reactions involve different lattice oxygen sites.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab., CA (US); Univ. of California, Berkeley, CA (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20076103
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 192; Journal Issue: 1; Other Information: PBD: 15 May 2000; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 10 SYNTHETIC FUELS; PROPANE; OXIDATION; DEHYDROGENATION; VANADIUM OXIDES; CATALYTIC EFFECTS; COMBUSTION; ISOTOPE EFFECTS; DEUTERIUM COMPOUNDS

Citation Formats

Chen, K., Iglesia, E., and Bell, A.T. Kinetic isotopic effects in oxidative dehydrogenation of propane on vanadium oxide catalysts. United States: N. p., 2000. Web. doi:10.1006/jcat.2000.2832.
Chen, K., Iglesia, E., & Bell, A.T. Kinetic isotopic effects in oxidative dehydrogenation of propane on vanadium oxide catalysts. United States. doi:10.1006/jcat.2000.2832.
Chen, K., Iglesia, E., and Bell, A.T. Mon . "Kinetic isotopic effects in oxidative dehydrogenation of propane on vanadium oxide catalysts". United States. doi:10.1006/jcat.2000.2832.
@article{osti_20076103,
title = {Kinetic isotopic effects in oxidative dehydrogenation of propane on vanadium oxide catalysts},
author = {Chen, K. and Iglesia, E. and Bell, A.T.},
abstractNote = {Kinetic isotopic effects (KIEs) for oxidative dehydrogenation of propane were measured on 10 wt% V{sub 2}O{sub 5}/ZrO{sub 2}. Normal KIEs were obtained using CH{sub 3}CH{sub 2}CH{sub 3} and CD{sub 3}CD{sub 2}CD{sub 3} as reactants for primary dehydrogenation (2.8) and combustion (1.9) of propane and for secondary combustion of propene (2.6), suggesting that in all cases C-H bond dissociation is a kinetically relevant step. CH{sub 3}CH{sub 2}CH{sub 3} and CH{sub 3}CD{sub 2}CH{sub 3} reactants led to normal KIEs for dehydrogenation (2.7) and combustion (1.8) of propane, but to a very small KIE (1.1) for propene combustion. These results show that the methylene C-H bond is activated in the rate-determining steps for propane dehydrogenation and combustion reactions. The rate-determining step in secondary propene combustion involves the allylic C-H bond. In each reaction, the weakest C-H bond in the reactant is cleaved in the initial C-H bond activation step. The measured propane oxidative dehydrogenation KIEs are in agreement with theoretical estimates using a sequence of elementary steps, reaction rate expression, and transition state theory. The much smaller KIE for propane oxidative dehydrogenation (2.8) than the maximum KIE (6) expected for propane thermal dehydrogenation indicates the participation of lattice oxygen. The different KIE values for propane primary dehydrogenation and combustion suggest that these two reactions involve different lattice oxygen sites.},
doi = {10.1006/jcat.2000.2832},
journal = {Journal of Catalysis},
issn = {0021-9517},
number = 1,
volume = 192,
place = {United States},
year = {2000},
month = {5}
}