Hydrogen Evolution by Photocatalytic Steam Reforming of Methane over Pt/TiO2

Photocatalytic reaction of CH, gas with H2O vapor over Pt/TiO2 at around room temperature (ca 323 K) was examined in a flow reactor. H-2 and CO2 were the main products, and only trace amounts of C2H6, C2H4, and CO were observed. After an induction period, the molar ratio of H-2 to CO2 in the outlet gas became close to 1.7. Thus, the main reaction is suggested to be: CH4+2H(2)O(g)-> 4H(2)+CO2, which can be referred to as photocatalytic steam reforming of methane (PSRM). The reaction would be promoted by photoexcited electrons and holes, which were generated by band gap photoexcitation of the TiO2 photocatalyst. In addition, the effects of reaction parameters, such as molar ratio of CH4 to H2O, total flow rate, noble-metal cocatalysts, wavelength of irradiating light, amounts of catalysts, and recycling efficiency of the p-Pt/TiO2 photocatalyst via light deposition of preformed Pt nanoparticles on P25, on the hydrogen evolution were investigated.