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2 Polish Journal of Chemistry

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Kinetics of the Propane Oxidative Dehydrogenation on Vanadia/Ceria and Vanadia/Ceria Doped by Potassium Catalysts

100%

Grabowski R.

Polish Journal of Chemistry

2006

tom Vol. 80, nr 5

791-804

Oxidative dehydrogenation of propane (ODH) over V2O5/CeO2 and V2O5/CeO2 doped with K was carried out by measuring conversions and selectivities for various feed compositions, contact times and temperatures.Modified byAndersson andCreaser version of Mars van Krevelen (MK) model and Eley-Rideal Steady State Adsorption model (ER-SSAM) were applied for the description of this reaction, and the activation energies and the pre-exponential factors obtained on the basis of these models were calculated. The calculations showed that both models describe adequately this reaction. The activation energies for the reoxidation of the catalyst, calculated in the frame of these models, are similar, but the fitting error for the ER-SSAMmodel is lower by about 5.5% and 2.3% forV2O5/CeO2 and V2O5/CeO2 doped with K, respectively compared to theMKmodel. It has been found in the frame of the ER-SSAM model that the direct total oxidation of propane represents about 5% of the consecutive propene oxidation. Addition of potassium exhibits a strong inhibitory effect on the consecutive propene combustion, decreasing its participation in the entire combustion. The decrease of the relevant rate constant is due mainly to the decrease of the pre-exponential factor. The activation energy is practically unchanged by the potassium additive. Total oxidation products (CO and CO2) arise from consecutive combustion of propene and parallel oxidation of propane.

Oxidative Dehydrogenation of Propane on Supported Mlybdena Catalysts: Effect of the Support Nature and Additives

100%

Klisińska A. , Samson K. , Grzybowska B.

Polish Journal of Chemistry

2003

tom Vol. 77 / nr 12

1867-1874

Oxidative dehydrogenation of propane has been studied on molybdena deposited on SiO2, Al2O3, TiO2, and MgO. The catalytic performance depended on the support nature, the selectivity to propene at iso-conversion decreasing in the sequence: MoOx/SiO2 >MoOx/Al2O3 ~ MoOx/TiO2 > MoOx/MgO. Introduction of the K, Cr , Ni and V additives to MoOx/SiO2 and Cr to MoOx/MgO catalysts led to the increase of the total activity. The increase of the selectivity to propene was observed for the Cr and Ni additives, whereas the K and V in the MoOx/SiO2 catalysts decreased the selectivity (K and higher amounts of V), or did not affect it (lower amounts of vanadium).