Sunfuels from CO2 exhaust emissions: Insights into the role of photoreactor configuration by the study in laboratory and industrial environment

Direct photoconversion of CO2 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 CO2 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 CO2 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.