EFFECT OF TEMPERATURE, PRESSURE AND VOLUME OF REACTING PHASE ON PHOTOCATALYTIC CO2 REDUCTION ON SUSPENDED NANOCRYSTALLINE TiO2

The effect of temperature, pressure and volume of reactant solution on the photocatalytic reduction of CO2 at suspended TiO2 was studied in an annular batch photoreactor. Reaction products in the liquid phase (methanol, formaldehyde) and in the gas phase (methane, ethane, carbon monoxide, molecular oxygen and hydrogen) were analysed by gas chromatography. The photocatalytic reduction of CO2 was not sensitive significantly to small temperature variations within 10 K. The CO2 pressure at carbonation of the solution influenced the selectivity of the CO2 conversion to methane and methanol, while the dihydrogen yield was higher by two orders of magnitude and independent of the pressure. The dependence of the product yields on the volume of the liquid phase confirmed the fact that the requirement for perfect mixing was difficult to fulfil for the annular configuration of the reactor.