Insertion of porous chromia in gamma-zirconium phosphate and its catalyticperformance in the oxidative dehydrogenation of propane

An expanded phase of acetate-hydroxide of Cr(III) intercalated into gamma-z irconium phosphate has been isolated by refluxing a solution formed by chro mium(III) acetate-hydroxide and gamma-zirconium phosphate, previously dispe rsed in 1:1 water-acetone solution at 353 K. By calcination of this phase a t 623 K under vacuum, an intercalated compound with a basal spacing of 1.73 nm and a surface area of 147 m(2) g(-1) was obtained. A temperature-progra mmed reduction study reveals that this solid contains a little amount of ch romium in high oxidation state. However, when the precursor is heated at 67 3 K, a collapsed structure with a low surface area was obtained. The insert ed porous chromia in gamma-zirconium phosphate calcined at 623 K is active in the oxidative dehydrogenation of propane at 623 K with 58% conversion an d 10% of selectivity to propene. When this material is calcined at 823 Kin air, it is also active in this reaction but only at high temperature, 823 K being necessary to attain catalytic properties similar to those observed f or the catalyst prepared at low temperature.