Photocatalytic CO₂ reduction with H₂O vapors using montmorillonite/TiO₂ supported microchannel monolith photoreactor

In this study, the performance of a montmorillonite (MMT)/TiO₂ coated monolith photoreactor was tested for the photocatalytic CO₂ reduction. CH₄ and CO were the main products having yield rates of 139 and 52μmolegcatal.^-1h^-1, respectively. The other adequately significant products were C₂H₄, C₂H₆, C₃H₆ and C₃H₈. The catalytic reactor performance for CH₄ production was in the order of MMT-TiO₂-monolith (139μmolegcatal.^-1h^-1)>TiO₂-monolith (82μmolegcatal.^-1h^-1)>MMT-TiO₂-cell (43μmolegcatal.^-1h^-1)>TiO₂-cell (7.7μmolegcatal.^-1h^-1). The higher yield rates in monolith photoreactor were due to the higher illuminated surface area and efficient light utilization. In addition, the profound hydrocarbon yield rates over MMT/TiO₂ nanocatalyst supported microchannels were due to the efficient production and utilization of charges. The reaction rate and the adsorption-desorption phenomenon was postulated according to the Langmuir-Hinshelwood (L-H) model. A simple kinetic equation, derived to model the coupled effect of adsorptive photocatalytic reduction and oxidation, fitted-well with the experimental data.