Synergetic effects promoted by in operandi surface reconstructions of oxides
(1997) 3rd World Congress on Oxidation Catalysis — Location: SAN DIEGO(Ca) (21.September.1997)
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- Synergetic effects are observed in the selective oxidation of isobutene to methacrolein when catalysts are prepared by mechanically mixing MoO3 with BiPO4. Both higher conversion and selectivity to methacrolein are observed. Catalyst characterization was carried out before and after catalytic tests. Scanning electron microscopy revealed that, when mixed with BiPO4, the (010) faces of the MoO3 crystals, known to be non selective, reconstructed to more active and selective (100) faces during the test. No effect was observed with pure MoO3 in the same conditions. In agreement with previous results, there was no indication of mutual contamination. The results lead to conclude that the two effects, namely the increase in activity and selectivity as well as the reconstruction, are linked and are both due to a remote control mechanism. This remote control is due to the action of spillover oxygen "Oso" generated by BiPO4 (the "donor") on MoO3 (behaving as an Oso "acceptor"). This confirms the interpretation given to identical results with mixtures of MoO3 and alpha-Sb2O4 (which, as BiPO4, is known to be an Oso donor) and reinforces the conclusion that the origin of the synergy is not mutual contamination. As different donors have the same effects, the conclusion is that the synergy is due to spillover oxygen and not to the chemical nature of the phase mixed with MoO3.
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Gaigneaux, E., Naud, J., Ruiz, P., & Delmon, B. (1997). Synergetic effects promoted by in operandi surface reconstructions of oxides. Studies in Surface Science and Catalysis, 110, 185-196. https://doi.org/10.1016/S0167-2991(97)80978-0 (Original work published 1997)