Oxidative Dehydrogenation Of Isobutane Research Articles

Sol-gel processing of silica supported Ni and Co molybdate catalysts used for isoC 4 alkane oxidative dehydrogenation

A novel sol-gel route has been developed to prepare silica supported Ni and Co molybdate catalysts. The metal oxides obtained are homogeneously dispersed in the silica matrix and specifically for NiMoO 4 the high-temperature β-phase which is catalytically more active has been found to be stable at room temperature. The catalytic activities of the silica supported stoichiometric Ni and Co molybdates prepared by sol-gel method have been tested continuously in the oxidative dehydrogenation of isobutane.

Oxidative Dehydrogenation of Isobutane over Supported Chromium Oxide on Lanthanum Carbonate

Oxidative Dehydrogenation of Isobutane over Supported Chromium Oxide on Lanthanum Carbonate

Oxidative dehydrogenation of isobutane to isobutylene over supported transition metal oxide catalysts

Various supported transition metal oxides have been tested for the oxidative dehydrogenation of isobutane to isobutylene. Chromium oxide supported on lanthanum carbonate has been found to be active and selective for this reaction.

Oxidative dehydrogenation of isobutane on supported chromia catalysts

Oxidative dehydrogenation, ODH, of isobutane has been performed on chromia supported on SiO 2, Al 2O 3, TiO 2, ZrO 2 and MgO. The potassium promoted (K/Cr= 0.1) catalysts have also been examined. The supported chromia has been found active in the ODH of isobutane at relatively low temperatures 200–400°C, the total activity and selectivity to isobutene depending on the nature of the support and the potassium presence. The highest selectivities to isobutene (ca. 70% at 5% conversion) and the isobutene yields of ca. 9% have been obtained for Cr/O xTiO 2 and K-promoted CrO x/Al 2O 3 preparations.

Thermal stability and catalytic properties of the Wells-Dawson K6P2W18O62·10H2O heteropoly compound in the oxidative dehydrogenation of isobutane to isobutene

The thermal stability of the Wells-Dawson heteropoly compound K6P2W18O62·10H2 was examined under both reducing and oxidizing conditions, and its structural and morphological evolution was characterized by several complementary solid state techniques. It is shown that the primary structure of this compound remains intact up to 770 K, while at higher temperature structural changes and rearrangements are observed. These modifications depend considerably on the treatment conditions and catalyst composition. Under oxidizing conditions the Wells-Dawson compound rearranges with formation of a mixed phase containing the Keggin-type unit K3PW12O40 and the hexatungstate K2W6O19. Furthermore, the catalytic activity in the oxidation of isobutane is affected considerably by these changes. The best catalytic performance was shown by the rearranged Wells-Dawson compound.

Selective oxidative dehydrogenation of isobutane over unidimensional aluminophosphate molecular sieves (AlPO4-5, AlPO4-41, AlPO4-25)

Unidimensional aluminophosphate molecular sieves (AlPO4-5, AlPO4-41, AlPO4-25) are found to be selective for the oxidative dehydrogenation of isobutane (2-methylpropane) to isobutene (2-methylprop-1-ene) and AlPO4-5 with a twelve-membered ring pore shows relatively high conversion.

Oxidative Dehydrogenation of Isobutane over Monoliths at Short Contact Times

Isobutylene can be produced with high selectivity and conversion by oxidative dehydrogenation of isobutane in air or oxygen over a ceramic foam monolith coated with Pt at contact times of ∼ 5 ms in an atmospheric pressure reactor operating at 800 to 900°C. Total olefin selectivities up to 80% (40% isobutylene, 40% propylene) at 60% conversion of isobutane are achieved in an autothermal process with higher reactant conversion when the reactants are preheated up to 400°C. No carbon build-up is observed at molar isobutane-to-oxygen feed ratios up to 2.5, and the catalyst shows no deactivation over at least several weeks of operation. Maximum isobutylene selectivity occurs at a fuel-to-oxygen ratio of 1.4 at contact times ≤ 5 ms, while propylene yield is maximized at longer contact times and at higher fuel-to-oxygen ratios. The total selectivity to methane, ethane, and ethylene is always much less than the total selectivity to isobutylene and propylene. A simple reaction mechanism can explain these products. Surface oxygen abstracts a hydrogen from isobutane resulting in an isobutyl group on the surface. On the Pt surface, β-elimination reactions than take place, leading to either isobutylene or propylene production. The small amounts of smaller hydrocarbons compared to n-butane oxidation or to homogeneous cracking are explained by the absence of a β-alkyl group on the isobutyl species adsorbed at a 3° carbon.