Reaction of butane to isobutane on silica-supported 12-tungstosilicic acid

Abstract

The heteropolyacids 12-tungstosilicic acid (TSA), 12-tungstophosphoric acid (TPA), 12-molybdosilicic acid (MSA) and 12-molybdophosphoric acid (MPA) were supported on SiO₂ and examined in the gas–solid phase reaction of butane to isobutane. Use of a support was effective for TSA and TPA whereas no reaction was observed with MSA or MPA. Effectiveness of the support for TSA was observed with ZrO₂ and Al₂O₃ but not with TiO₂, SnO₂, or Fe₂O₃. The most active catalyst was prepared by impregnating SiO₂ with an aqueous solution of 40 wt% TSA followed by water evaporation and heat-treating in air at 300 °C (40% TSA/SiO₂). The catalytic activity was more than doubled when a physical mixture of 40% TSA/SiO₂ and Pt/ZrO₂ was used.