A simplified partial ionic charge model to evaluate the role played by bismuth pyrostannate in multiphase catalysts for the selective oxidation of isobutene to methacrolein

摘要

A simplified model based on partial ionic charges, developed by Jolivet to rationalise the condensation of cations in aqueous phase, is used to evaluate the electro-donating properties of binary and ternary oxide phases within the context of the remote control mechanism, in relationship with their use as heterogeneous selective oxidation catalysts. The model is applied to calculate partial ionic charges on the oxygen atoms in various binary oxides (Bi2O3, Sb2O4), or ternary systems (antimonates, phosphates, molybdates, ferrates) which are widely used in partial oxidation of alkenes. After being validated by referring to catalytic data on the partial oxidation of isobutene to methacrolein from the literature, the model is more particularly implemented to locate bismuth pyrostannate (Bi2Sn2O7), an oxide whose interest as selective oxidation catalyst was recently demonstrated, along an already available empirical scale of donor-acceptor power of spill-over oxygen. The limitations of this simplified approach are also discussed. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 29]