Sunfuels from CO 2 exhaust emissions: Insights into the role of photoreactor configuration by the study in laboratory and industrial environment

Abstract Direct photoconversion of CO 2 from exhaust emissions into fuels and chemicals is one of the most ambitious challenges to a greater and more effective use of the solar source. Through an extensive and systematic evaluation of CO 2 photoreduction process, both in aqueous media and in gas-vapour stream for over 120 h, this work addresses the role of the photoreactor configuration on the CO 2 reduction efficiency, leading the study from laboratory to industrial environment, probably for the very first time. Therefore, the performance of a continuously stirred “semi-batch” (SB) photoreactor, a packed-bed (PB) photoreactor and a multi-tubular (MT) photoreactor has been compared in term of efficiency, products distribution and available energy. The results of the photocatalytic tests demonstrate a strong influence of process conditions on the photocatalyst performance and on the reaction path. The packed-bed (PB) configuration reports a maximum “apparent quantum efficiency” of about 6.0% and a net thermal energy of 0.3 kW h/m 2 generated in 120 h.