Photocatalytic carbon dioxide reduction to fuels in continuous flow monolith photoreactor using montmorillonite dispersed Fe/TiO2 nanocatalyst

Abstract

Photocatalytic conversion of CO2 to fuels has attracted immense attention because it offers a cleaner energy technology and safer environment. In this study, performance of structured montmorillonite (MMT) dispersed Fe-doped titanium dioxide (Fe/TiO2) nanocomposite was tested for dynamic photo-induced CO2 reduction by H2 to fuels. Cordierite monolithic support was employed in order to improve the photo-activity and reusability of Fe-MMT/TiO2 nanocomposite in a CO2 utilization process. MMT-clay supported Fe/TiO2 samples were prepared by a controlled and direct sol-gel method and were dip-coated over the monolith micro-channels. The efficiency of Fe-loaded MMT/TiO2 for CO2 reduction by H2 toward CO was investigated using a cell type and a monolith photo-reactor under UV-light. The maximum CO yield over 3 wt % Fe-10 wt % MMT-loaded TiO2 catalyst reached 166 µmole g-catal.-1 h-1 at selectivity 99.70%, considerably higher than the amount of CO produced over the MMT/TiO2 (16 µmole g-catal.-1 h-1) and the pure TiO2 (5 µmole g-catal.-1 h-1) catalysts. The other products observed with adequate amounts were CH4 and C2H6. More importantly, photo-activity and stability of Fe-MMT/TiO2 catalyst for CO evolution was significantly improved using monolith photo-reactor compared to the cell type reactor under the same operating conditions. This enactment was evidently due to higher quantum efficiency of monolith photoreactor, improved adsorption-desorption process in a catalyst coated monolith channels and hindered charges recombination by Fe. The reusability of catalyst loaded over the monolithic support showed greater recycling capability than the catalyst dispersed in a cell reactor. This development confirmed higher photo-activity of Fe-MMT/TiO2 photo-catalyst loaded over monolithic support for CO2 photo-reduction to cleaner fuels.