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

Abstract

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 (it 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°C leads to the best catalytic performance, i.e., good activity and high selectivity.