Catalytic and photocatalytic water gas shift reaction (WGSR) using a continuous flow, gas phase reactor

Abstract

Abstract A series of different M/TiO2 catalysts are prepared, where M\u202f=\u202fAu, Pt, Pd and Ag, with a 0.2\u202fwt% loading, and tested for activity as catalysts and photocatalysts for the water gas shift reaction, WGSR, using a continuous flow, gas phase reactor. For both the thermal (dark) and photocatalytic (UV irradiated) WGSR the best catalyst/photocatalyst is Au/TiO2. The kinetics of the WGSR is studied as a function of reactor temperature, Au loading and concentrations of CO and H2O. Langmuir-Hinshelwood kinetics are observed for the photocatalytic WGSR with non-competitive adsorption of the CO and H2O, whereas those for the thermal WGSR fit a slightly more complex, previously reported, reaction mechanism. At 125\u202f°C, with a 0.2\u202fwt% loading, the Au/TiO2 photocatalysis of the WGSR is very efficient, with a formal quantum efficiency for 1/2H2 production of 57 %. The potential scale up of the relatively efficient photocatalytic WGSR is discussed briefly.