Photocatalytic CO2 reduction by CH4 over montmorillonite modified TiO2 nanocomposites in a continuous monolith photoreactor

Abstract

In this study, the performance of montmorillonite (MMT) modified TiO2 nanocomposites for photocatalytic CO2 reduction with CH4 in a continuous monolith photoreactor has been investigated. The MMT modified TiO2 nanocomposites were dip-coated over monolith channels and were characterized by XRD, SEM, TEM, XPS, N2-adsorption-desorption and UV-vis spectroscopy. The MMT produced anatase phase of TiO2 and reduced TiO2 crystallite size from 19 nm to 13 nm. CO was the major reduction product with a yield rate of 237.5 μmol g-catal.-1 h-1 over 10 wt.% MMT-loaded TiO2 at 100 °C, and CO2/CH4 feed ratio 1.0. The photoactivity of MMT-loaded TiO2 monolithic catalyst was 2.52 times higher than bare TiO2. Likewise, low concentrations of C2H6, CH3OH, C3H6 and C3H8 were detected in the products mixture. These results inferred MMT modified TiO2 and monolith photoreactor were beneficial for enhancing photocatalysis process with appreciable productivity. The stability test revealed photoactivity of MMT-loaded TiO2 nanocomposites partially diminished in recycle runs.