Photocatalytic Reduction of CO2 Using Ti–MCM-41 Photocatalysts in Monoethanolamine Solution for Methane Production

Photocatalytic reduction of carbon dioxide (CO2) to form a valuable energy source of methane (CH4) in monoethanolamine (MEA) solution is first investigated by mesoporous photocatalysts of Ti–MCM-41 in this study. The MEA solution was chosen as the absorbent and reductant because amine absorption is one of the most popular methods for CO2 capture from flue gas streams. Also, it is intended to integrate the CO2 capture and utilization into one process. The photocatalytic results of methane yields indicated that MEA served as a better reductant than water and NaOH which have been commonly used for CO2 reduction. For the best photocatalyst of Ti–MCM-41(50) manufactured at a Si/Ti molar ratio of 50, its methane yield (62.42 μmol/g of cat.) was much higher than that of commercial P25 photocatalyst after 8 h of UV illumination. A photoreduction quantum efficiency (PQE) of 9.18% was achieved.