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Title: Oxidative dehydrogenation of propane over vanadia-based catalysts supported on high-surface-area mesoporous MgAl2O4

Abstract

The oxidative dehydrogenation of propane to propene was investigated over a series of novel vanadia-based catalysts supported on high-surface-area magnesium spinel. A mesoporous MgAl2O4 support was synthesized via a low-temperature sol gel process involving the heterobimetallic alkoxide precursor, Mg[Al(O iPr)4]2. A high-purity catalyst support was obtained after calcination at 1173 K under O2 atmosphere and active vanadia catalysts were prepared from the thermolysis of OV(O tBu)3 after grafting onto the spinel support. MgAl2O4-supported catalysts prepared in this manner have BET surface areas of 234 245 m2/g. All of the catalysts were characterized by X-ray powder diffraction, and Raman, solid-state NMR, and diffuse-reflectance UV vis spectroscopy. At all vanadium loadings the vanadia supported on MgAl2O4 exist as a combination of isolated monovanadate and tetrahedral polyvanadate species. As the vanadium surface density increases for these catalysts the ratio of polyvanadate species to isolated monovanadate species increases. In addition, as the vanadium surface density increases for these catalysts, the initial rate of propane ODH per V atom increases and reaches a maximum value at 6 VOx/nm2. Increasing the vanadium surface density past this point results in a decrease in the rate of propane ODH owing to the formation of multilayer species in whichmore » subsurface vanadium atoms are essentially rendered catalytically inactive. The initial propene selectivity increases with increasing vanadium surface density and reaches a plateau of {approx}95 percent for the V/MgAl catalysts. Rate coefficients for propane ODH (k1), propane combustion (k2), and propene combustion (k3) were calculated for these catalysts. The value of k1 increases with increasing VOx surface density, reaching a maximum at about 5.5 VOx/nm2. On the other hand, the ratio (k2/k1) for V/MgAl decreases with increasing VOx surface density. The ratio (k3/k1) for both sets of catalysts shows no dependence on the vanadia surface density. The observed trends in k1, (k2/k1), and (k3/k1) are discussed in terms of the surface structure of the catalyst.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Director. Office of Science. Office of Basic Energy Sciences. Chemical Sciences Geosciences and Biosciences Division (US)
OSTI Identifier:
839229
Report Number(s):
LBNL-54399
Journal ID: ISSN 0021-9517; JCTLA5; R&D Project: 406201; TRN: US200509%%336
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 226; Journal Issue: 1; Other Information: Journal Publication Date: August 15, 2004; PBD: 1 Jun 2004; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALKOXIDES; CALCINATION; CATALYST SUPPORTS; CATALYSTS; COMBUSTION; DEHYDROGENATION; MAGNESIUM; PRECURSOR; PROPANE; PROPYLENE; SOL-GEL PROCESS; SPECTROSCOPY; SPINELS; SURFACE AREA; VANADIUM; PROPANE OXIDATIVE DEHYDROGENATION VANADIA

Citation Formats

Evans, Owen R, Bell, Alexis T, and Tilley, T Don. Oxidative dehydrogenation of propane over vanadia-based catalysts supported on high-surface-area mesoporous MgAl2O4. United States: N. p., 2004. Web. doi:10.1016/j.jcat.2004.06.002.
Evans, Owen R, Bell, Alexis T, & Tilley, T Don. Oxidative dehydrogenation of propane over vanadia-based catalysts supported on high-surface-area mesoporous MgAl2O4. United States. https://doi.org/10.1016/j.jcat.2004.06.002
Evans, Owen R, Bell, Alexis T, and Tilley, T Don. 2004. "Oxidative dehydrogenation of propane over vanadia-based catalysts supported on high-surface-area mesoporous MgAl2O4". United States. https://doi.org/10.1016/j.jcat.2004.06.002.
@article{osti_839229,
title = {Oxidative dehydrogenation of propane over vanadia-based catalysts supported on high-surface-area mesoporous MgAl2O4},
author = {Evans, Owen R and Bell, Alexis T and Tilley, T Don},
abstractNote = {The oxidative dehydrogenation of propane to propene was investigated over a series of novel vanadia-based catalysts supported on high-surface-area magnesium spinel. A mesoporous MgAl2O4 support was synthesized via a low-temperature sol gel process involving the heterobimetallic alkoxide precursor, Mg[Al(O iPr)4]2. A high-purity catalyst support was obtained after calcination at 1173 K under O2 atmosphere and active vanadia catalysts were prepared from the thermolysis of OV(O tBu)3 after grafting onto the spinel support. MgAl2O4-supported catalysts prepared in this manner have BET surface areas of 234 245 m2/g. All of the catalysts were characterized by X-ray powder diffraction, and Raman, solid-state NMR, and diffuse-reflectance UV vis spectroscopy. At all vanadium loadings the vanadia supported on MgAl2O4 exist as a combination of isolated monovanadate and tetrahedral polyvanadate species. As the vanadium surface density increases for these catalysts the ratio of polyvanadate species to isolated monovanadate species increases. In addition, as the vanadium surface density increases for these catalysts, the initial rate of propane ODH per V atom increases and reaches a maximum value at 6 VOx/nm2. Increasing the vanadium surface density past this point results in a decrease in the rate of propane ODH owing to the formation of multilayer species in which subsurface vanadium atoms are essentially rendered catalytically inactive. The initial propene selectivity increases with increasing vanadium surface density and reaches a plateau of {approx}95 percent for the V/MgAl catalysts. Rate coefficients for propane ODH (k1), propane combustion (k2), and propene combustion (k3) were calculated for these catalysts. The value of k1 increases with increasing VOx surface density, reaching a maximum at about 5.5 VOx/nm2. On the other hand, the ratio (k2/k1) for V/MgAl decreases with increasing VOx surface density. The ratio (k3/k1) for both sets of catalysts shows no dependence on the vanadia surface density. The observed trends in k1, (k2/k1), and (k3/k1) are discussed in terms of the surface structure of the catalyst.},
doi = {10.1016/j.jcat.2004.06.002},
url = {https://www.osti.gov/biblio/839229}, journal = {Journal of Catalysis},
issn = {0021-9517},
number = 1,
volume = 226,
place = {United States},
year = {Tue Jun 01 00:00:00 EDT 2004},
month = {Tue Jun 01 00:00:00 EDT 2004}
}