Propane ammoxidation to acrylonitrile over a tin-based mixed-oxide catalyst

The catalytic properties of a Sn/V/Sb mixed oxide for propane ammoxidation to acrylonitrile are studied in this paper. First, preparing the sample with a coprecipitation method from an ethanolic phase, the amounts of antimony and vanadium were changed in order to optimize the relative atomic ratio of the ternary catalyst. The results obtained indicate that vanadium is responsible for the paraffin activation and antimony for the insertion of nitrogen in the molecule tit can be considered as an acrylonitrile selectivity modulator). Other samples, with the optimized atomic ratio, were also prepared using a similar coprecipitation technique (but by dissolving the starting materials with iso-butanol or water instead of ethanol), or by solid state reaction between oxide and tin hydroxide, The sample prepared using ethanol shows the best catalytic performance. This solvent makes the partial alkoxides quite stable in solution and brings about better coprecipitation with a more intimate mixture of tin, antimony and vanadium. Finally, the thermal transformation of the precursor of this sample was followed during calcination, both in air and in nitrogen with several characterization techniques. The thermal treatment in air at 700 degrees C leads to the best catalytic performance, i.e., goad activity and high selectivity. (C) 1998 Elsevier Science B.V. All rights reserved.