Iron antimony oxide catalysts for the ammoxidation of propene to acrylonitrile: comments on the method of preparation of tellurium promoted catalysts

Three methods of catalyst preparation for tellurium promoted iron antimony oxide catalysts are investigated: (a) co-precipitation, (b) impregnation an d (c) reaction of solid oxides. For all three methods, the addition of Te i ncreases the selectivity for acrylonitrile. significantly. For catalysts pr epared by co-precipitation, this effect is only apparent at low Te concentr ations whereas, for the other two preparation methods, the positive effect on selectivity is maintained at higher doping levels. The catalysts are cha racterised using X-ray diffraction and X-ray photoelectron spectroscopy. Fo r the Fe30Sb60Te2Ox formulations prepared using the three methods, a simila r Te/Sb surface atomic ratio was observed which is consistent with the simi lar specific activity observed with all three catalysts, indicating that th e three methods of preparation can prepare similar surfaces following calci nation and catalyst testing. However, the co-precipitation method gives cat alyst surface areas approximately three times higher than the other two met hods and, consequently, gives the best catalyst performance. (C) 2001 Elsev ier Science B.V. All rights reserved.