Photo-thermo-catalytic H2 production over flame made CeO2-Pt/TiO2

The photo-thermo-catalytic production of H2 by methanol steam reforming (MSR) was studied in an innovative home-made bench scale setup which allows to evaluate the synergistic effect of heat and UV–vis light irradiation. The variation of the concentrations of all reactants, intermediates, and products as a function of temperature were monitored in real-time by calibrated mass spectrometry. CeO2-Pt/TiO2 composite photocatalysts were prepared in continuous and single step by flame spray pyrolysis (FSP) with different ceria loading (5 or 50 wt%). The catalytic performance of the FSP materials were compared with that of pure Pt/TiO2 or CeO2 alone or their mechanical mixture. It was found that temperature strongly affects the photocatalytic performance in terms of methanol and water conversion (XCH3OH and XH2O), hydrogen production rate (rH2), and selectivity towards the different products of methanol oxidation (formaldehyde, carbon monoxide and carbon dioxide). The addition of 5 wt% of ceria to 0.75 wt% Pt/TiO2 led to an improved photo-thermo-catalytic performance at temperature above 150 °C. In contrast, a high ceria loading up to 50 wt% was found to be detrimental. The best catalytic performance was achieved over the catalyst obtained by mechanical mixing of 50 wt% of CeO2 with Pt/TiO2 leading to a significant increase of XCH3OH, XH2O, rH2 and selectivity to CO2 with a maximum at 350 °C of ca. 100 %, 17 %, 431 mmolH2 h−1 gcat−1 and 18 %, respectively, due to the parallel Water Gas Shift (WGS) reaction promoted by CeO2.