The preparation, characterisation and catalytic activity of tungsten bronzes

Abstract

The structure and catalytic aspects of tungsten bronzes have been considered. A series of potassium tungsten bronzes, KxW03, 0.05 =< x =< 0.8, and the corresponding series of sodium tungsten bronzes, NaxW03, 0.05 =< x =< 0.8 were prepared by a thermal method. The thermal stability of the prepared samples was studied in the presence of both an oxidising and a reducing gas. The number and strength of acid sites present on the bronzes was studied by temperature-programmed desorption of ammonia. Xps, xrd and electrical resistivity measurements gave information about the bulk and surface properties of the bronzes. The activity of the tungsten bronzes for isopropanol decomposition and propene metathesis was investigated. In addition, a silica-supported tungsten bronze and a copper-potassium tungsten bronze, CUyKxW03, were prepared. Their structures and catalytic values were considered.