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Mass and heat transfer effects on the oxidative dehydrogenation of propane (ODP) over a low loaded VOx/Al2O3 catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
43609 45979 2007 11 PDF Available
Title
Mass and heat transfer effects on the oxidative dehydrogenation of propane (ODP) over a low loaded VOx/Al2O3 catalyst
Abstract

A low loaded VOx/Al2O3 catalyst (1.4 wt.% V) was prepared by saturation-impregnation of a commercial γ-alumina support. The nature, distribution and redox properties of surface VOx species were investigated by means of in situ UV–vis and TPR tests as well as by O2 pulse experiments. Macroscopic structural properties of the catalyst were determined from XRD and BET (N2 physisorption) analysis including pore size distribution. It was found that propene selectivity in the oxidative dehydrogenation of propane with oxygen in the temperature range of 673–773 K decreases with an increase in the size of the catalyst particles. Based on a simulation of intraparticle concentration and temperature profiles using developed intrinsic power-law kinetics, it was concluded that the dependence of propene selectivity on particle size is related to propene accumulation inside the particle pores and further oxidation. The kinetic evaluation indicated that total propene selectivity suffers exclusively from consecutive propene combustion to CO and CO2, whereas the reaction of propane with lattice oxygen of VOx species selectively yields propene. Moreover, the kinetic model in agreement with the experiment predicts an increase in propene selectivity with temperature. This is due to slightly higher activation energy of propene formation than its combustion. Since the measured effects were predicted quantitatively by the kinetic model, it, therefore, can be used for a precise design of extended microkinetic studies with this catalyst.

Graphical abstractA low loaded VOx/Al2O3 catalyst (1.4 wt.% V) was prepared by saturation-impregnation of a commercial γ-alumina support. The nature, distribution and redox properties of surface VOx species were investigated by means of in situ UV–vis and TPR tests as well as by O2 pulse experiments. Macroscopic structural properties of the catalyst were determined from XRD and BET (N2 physisorption) analysis including pore size distribution. It was found that propene selectivity in the oxidative dehydrogenation of propane with oxygen in the temperature range of 673–773 K decreases with an increase in the size of the catalyst particles. Based on a simulation of intraparticle concentration and temperature profiles using developed intrinsic power-law kinetics, it was concluded that the dependence of propene selectivity on particle size is related to propene accumulation inside the particle pores and further oxidation. The kinetic evaluation indicated, that total propene selectivity suffers exclusively from consecutive propene combustion to CO and CO2, whereas the reaction of propane with lattice oxygen of VOx species selectively yields propene. Moreover, the kinetic model in agreement with the experiment predicts an increase in propene selectivity with temperature. This is due to slightly higher activation energy of the ODP reaction compared to propene combustion. Since the measured effects were predicted quantitatively by the kinetic model, it, therefore, can be used for a precise design of extended microkinetic studies with this catalyst. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Vanadia; VOx/Al2O3; Oxidative dehydrogenation of propane; ODP; Kinetic model; Mass transport limitation; Particle modelling
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Mass and heat transfer effects on the oxidative dehydrogenation of propane (ODP) over a low loaded VOx/Al2O3 catalyst
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 323, 30 April 2007, Pages 66–76
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us