Reduction kinetics and catalytic activity of VO x /γ-Al 2 O 3 -ZrO 2 for gas phase oxygen free ODH of ethane

Vanadium Supported on Alumina and/or Zirconia Catalysts for the Selective Transformation of Ethane and Methanol

“…In general, the total H 2 -uptake increases when increasing the V-loading in good agreement with previous results reported by other authors [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. This suggests that all V-atoms are involved in the TPR experiments.…”

“…According to kinetic aspects of the ODH reactions [5][6][7]17,23,26,27,61,62] and the results obtained in the present work a simplified reaction network can be tentatively proposed. It must be mentioned that more catalytic data would be needed for a comprehensive kinetic analysis.…”

“…Supported vanadium oxide catalysts have been considered for many years the most promising catalysts in the ODH of C 2 -C 4 alkanes [4][5][6][7][8][9][10][11][12][13][14], although the nature of the optimal support is different depending on the nature of the alkane fed [5][6][7]14,15]. The catalytic behavior of supported vanadia catalysts can be related to [5][6][7][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]: (i) the nature of V n+ -O species, i.e., coordination, aggregation and oxidation state of V-species; (ii) the redox properties of the catalysts, i.e., the V 5+ /V 4+ ratio in reaction conditions, which are influenced by the presence of promoters and the nature of the metal oxide support; and (iii) the acid-base character of the catalysts (and support), which strongly influences the adsorption of reactants and the desorption of partial oxidation products and finally determines the selectivity to olefins. Depending on the support material and the VOx concentration, supported vanadium oxide can exist as isolated tetrahedral monovanadates, one or two-dimensional polyvanadate domains, or bulk V 2 O 5 crystallites [5][6][7]12,23].…”

“…Thus, zirconia has bifunctional properties as an acid and as a base, and high thermal stability. More interestingly ZrO 2 [25] and Al 2 O 3 -ZrO 2 [26,27] are appropriate supports for the synthesis of highly dispersed VOx-species. As highly-isolated vanadium species tend to overoxidize ethylene to a lower extent than more aggregated species [5][6][7][8][9][10][11] we have thought that by modifying the alumina support through the addition of zirconia, the ethylene decomposition could be mitigated.…”

Manganese‐containing redox catalysts for selective hydrogen combustion under a cyclic redox scheme

“…This approach to CL‐ODH involves the use of the redox catalyst to selectively combust the hydrogen co‐product from alkane dehydrogenation (DH); the DH reaction can occur either catalytically via a co‐catalyst or through thermal cracking. The redox catalyst is not intended to interact with the fed alkane and should be relatively inert toward hydrocarbons in general, a difference which distinguishes this method from catalytic ODH . Combustion of the hydrogen co‐product not only provides heat to the endothermic dehydrogenation reaction but also can shift the dehydrogenation equilibrium toward the product side.…”