Improving photoreduction of CO2 with water to CH4 in a novel concentrated solar reactor

CO2 photoreduction is an attractive process which allows the storage of solar energy and synthesis of solar fuels. Many different photocatalytic systems have been developed, while the alternative photo-reactors are still insufficiently investigated. In this work, photoreduction of CO2 with H2O into CH4 was investigated in a modified concentrating solar reactor, using TiO2 and Pt/TiO2 as the catalysts. The TiO2 and Pt/TiO2 samples were extensively characterized by different techniques including powder X-ray diffraction (XRD), N-2 adsorption/desorption and UV-vis absorption. The catalytic performance of the TiO2 and Pt/TiO2 samples in the gas phase was evaluated under unconcentrated and concentrated Xe-lamp light and nature solar light with different concentrating ratios. Various parameters of the reaction system and the catalysts were investigated and optimized to maximize the catalytic performance of CO2 reduction system. Compared with the normal light irradiation, the TiO2 and Pt/TiO2 samples show higher photocatalytic activity (about 6-7 times) for reducing CO2 into CH4 under concentrated Xe-lamp light and nature solar light. In the range of experimental light intensity, it is found that the concentration of the light makes it suitable for the catalytic reaction, and increases the utilization efficiency of the TiO2 and Pt/TiO2 samples while does not decrease the quantum efficiency. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.