Publications (2)2.62 Total impact
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Article: Catalytic dense membranes of doped Bi4V2O11 (BIMEVOX) for selective partial oxidation: chemistry of defects versus catalysis
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ABSTRACT: A catalytic dense membrane reactor (CDMR) is used to physically separate the reaction step from the reoxidation of the catalyst. By decoupling the redox mechanism prevailing in mild oxidation of hydrocarbons, the operating conditions may be optimized resulting in an increase of selectivity. The membranes are made up of BIMEVOX oxides, obtained by partial substitution of V in γ-Bi4V2O11 by ME (Co, Cu, Ta). Experiments performed on BIMEVOX dense membranes using propene and propane are described in terms of, (i) active sites on polished or unpolished surfaces, (ii) operating conditions (T, pO2 in the high oxygen partial pressure compartment), which determine the selectivity, either to mild oxidation products (acrolein, hexadiene, CO), or to partial oxidation products (CO, H2), and, (iii) nature of ME cations and relative properties. The discussion deals with the respective role of electronic versus oxide ion conductivities which depend on defects in the structure as well as on the redox properties of cations.Topics in Catalysis 04/2012; 38(1):169-179. · 2.62 Impact Factor -
Article: Effect of a current polarisation on BIMEVOX membranes for oxidation of propane in a Catalytic Dense Membrane Reactor
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ABSTRACT: A BICOVOX dense membrane covered with BICOVOX/Au cermet was investigated at 700°C in the partial oxidation of propane under OCV and under electrical bias. The propane conversion remained constantly equal to 12% whatever the conditions of polarisation. Hydrogen was the main product with a selectivity of 60%. At OCV, no product of oxidation was detected except water which could not be quantified. Under anodic polarisation, traces of CO were observed as well as a small increase of propylene content which can be explained by partial oxidation and oxidative dehydrogenation of propane, respectively. An anodic polarisation led to a decrease of hydrogen due to its oxidation into water. In contrast, an increase of the hydrogen content was observed under cathodic polarisation. However one cannot exclude some thermal cracking of propane, and the role of the BIMEVOX membrane in the catalytic process remains to be clarified.
