Page 54 - Book of Invited & Keynotes Talks

th
8 Biannual Conference on Chemistry - CHEM 08

Non-Conventional Oxidative Dehydrogenation of Propane to
Propylene over VOx/ZrO2 Catalysts
M. Mokhtar *, K. Narasimharao , A. Jedidi1, S. Basahel , S. Bawaked , T.
1
1
1
1
Ali1, N. Alyaser , K. Al-Majnouni , A. Al-Mutairi , A. Al-Zenaidi , A.
2
2
2
2
Toseef , N. Elwaer
3
3
1 Surface Chemistry and catalytic studies group, Department of Chemistry,
Faculty of Science, King Abdulaziz University, 21589 Jeddah, Saudi Arabia
2 Olefins and Aromatics – Regional Analytical, Technology and Innovation,
3
SABIC, Saudi Arabia

ABSTRACT
The development of simple, selective and energy saving process to produce
propylene from n-propane is of current interest in petrochemical industries.
Oxidative dehydrogenation of n-propane (ODHP) is one of such process, which
overcomes many drawbacks from the conventional steam reforming process of
hydrocarbons . The major advantage is the exothermic nature of the reaction, which
1
requires no additional energy to accelerate the rate of reaction. Control of olefins
selectivity in ODHP process is an important step and still it’s a challenge due to the
formation of undesired carbon oxides. Therefore, design of a propylene selective
catalyst that provides optimum level of lattice oxygen is important to minimize
carbon oxides formation . The control of active component-support interaction and
2
the acid character of the designed catalyst are necessary to maximize the adsorption
of n-propane and propylene and minimize the combustion of propylene. In the
ODHP process, catalysts should be active at moderate temperature to activate C-H
bond of n-propane without deep oxidation of produced alkenes. Vanadium based
catalysts are known to be very active in ODH reaction, which offered relatively high
n-alkane conversion and alkene selectivity 3-11 . Tetrahedral V species are proposed
5+
to be the active sites for ODH reaction, and isolated vanadate species were found
to be more active and selective than polymeric V2O5 species 12. Different transition
metal oxides such as ZrO2, SiO2, TiO2 and Al2O3 etc. were selected to disperse V
5+
species. Among the investigated supports, ZrO2 found to be a suitable support,
which provided a good dispersion of monolayer coverage of about 6.8 V atoms/nm 2
12 . Several contributing factors such as state of aggregation, vanadium species
coordination environment, oxygen vacancies of the catalyst, the redox ability of
V /V species and acidity of the catalysts influenced the catalytic ODH
5+
4+
performance 13, 14 . In our prior research, it was observed that there are usually strong
interactions between the ZrO2 support and the active component 15-17 . In this
research, it is our aim to develop a highly selective catalyst towards propylene
production in ODHP process. Primarily, we performed simulations using Density
Functional Theory on VASP program to estimate oxygen vacancy formation
energies for ZrO2 structures and possible atomic state of vanadium atoms over the

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