SUPPORTED VPO CATALYSTS FOR SELECTIVE OXIDATION OF BUTANE-III - EFFECT OF PREPARATION PROCEDURE AND SIO2 SUPPORT

The effects of the nature of silica support and removal of soluble van adium species by ethanol on the catalytic properties of silica-support ed VPO catalysts were investigated. Ethanol preferentially removes V+5 species. For a silica-supported sample of PIV ratio much lower than t wo, ethanol treatment resulted in a sample of higher PIV ratio and hig her selectivity for maleic anhydride in butane oxidation. The crystall ine VPO phases formed differed on a hydrophobic vs. hydrophilic silica . (VO)(2)P2O7 could be formed more easily on the former support. inter estingly, for all silica-supported catalysts, the maleic anhydride sel ectivity depended much more strongly on the PIV ratio than on the meth od of preparation, the nature of the silica, or the crystalline VPO ph ase present. (C) 1998 Elsevier Science B.V. All rights reserved.