Performance analysis of photocatalytic CO2 reduction in optical fiber monolith reactor with multiple inverse lights

Highlights: • A new optical fiber monolith reactor model for CO2 reduction was developed. • Methanol concentration versus fiber location and operation parameters was obtained. • Reaction efficiency increases by 31.1% due to the four fibers and inverse layout. • With increasing space of fiber and channel center, methanol concentration increases. • Methanol concentration increases as the vapor ratio and light intensity increase. - Abstract: Photocatalytic CO2 reduction seems potential to mitigate greenhouse gas emissions and produce renewable energy. A new model of photocatalytic CO2 reduction in optical fiber monolith reactor with multiple inverse lights was developed in this study to improve the conversion of CO2 to CH3OH. The new light distribution equation was derived, by which the light distribution was modeled and analyzed. The variations of CH3OH concentration with the fiber location and operation parameters were obtained by means of numerical simulation. The results show that the outlet CH3OH concentration is 31.1% higher than the previous model, which is attributed to the four fibers and inverse layout. With the increase of the distance between the fiber and the monolith center, the average CH3OH concentration increases. The average CH3OH concentration also rises as the light input and water vapor percentage increase, but declines with increasing the inlet velocity. The maximum conversion rate and quantum efficiency in the model are 0.235 μmol g−1h−1 and 0.0177% respectively, both higher than previous internally illuminated monolith reactor (0.16 μmol g−1h−1 and 0.012%). The optical fiber monolith reactor layout with multiple inverse lights is recommended in the design of photocatalytic reactor of CO2 reduction