Photocatalytic Carbon Dioxide and Methane Reduction to Fuels over La-promoted Titanium Dioxide Nanocatalyst

Abstract

Selective photocatalytic carbon dioxide (CO2) reforming of methane (CH4) to carbon monoxide (CO) and hydrocarbons over lanthanum loaded titanium dioxide (La/TiO2) nanoparticles has been investigated. TiO2 nanoparticles (NPs) with different La-loadings were synthesised using sol-gel method. The catalysts were characterised using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Photoluminescence (PL) spectroscopy. Pure crystallite and anatase phase TiO2 with hindered charge recombination were detected in the La-loaded TiO2 samples. The products obtained were mainly CO, followed by ethane (C2H6) and traces of propane (C3H8). Pure TiO2 was favourable for CO evolution, while La-loaded TiO2 samples promoted hydrocarbons formation. The 2 wt% La/TiO2 photocatalyst conferred the maximum C2H6 yield of 492.8 µmole/g-cat at CO2/CH4 feed ratio 1.0 and irradiation time 2 h. The enhanced photocatalytic performance can be attributed to efficient reactant adsorption with hindered charge recombination rate in the presence of La-metal.