Oxidation of propane to propylene oxide on gold catalysts

Propane epoxidation was carried out by sequential propane dehydrogenation-propylene epoxidation steps using a two-catalyst bed and H-2 and O-2 as the oxidant mixture. The propane dehydrogenation step used a Au/TiO2 catalyst that was active at the low temperature (443 K) used for the propylene, epoxidation step; the latter used a Au/TS-1 catalyst. In situ Au L-3-edge X-ray absorption near-edge structure and ultraviolet-visible measurements on Au/TiO2 under propane dehydrogenation conditions showed activation of oxygen on gold nanoparticles and evidence for the formation of adsorbed oxygen intermediate species responsible for the production of propylene. Propane epoxidation with H2 and 02 at 443 K and 0.1 MPa with the dual Au/TiO2 and Au/TS-1 catalysts resulted in an overall propane conversion of 2%, propylene selectivity of 57%, and propylene oxide selectivity of 8%, corresponding to a propylene oxide space-time yield of 4 gkg(cat)(-1)h(-1). The catalysts showed little deactivation and maintained their conversion and selectivity levels for the 12 h duration of the measurements. (c) 2008 Elsevier Inc. All rights reserved.