2022 Volume 101 Issue 3 Pages 43-49
The photocatalytic reduction of carbon dioxide into methanol over modified SiO2-Al2O3 supported TiO2 catalyst at atmospheric pressure was investigated. The SiO2-Al2O3 supported TiO2 catalyst was modified by coating the bimetallic metal (Ni-Cu) using the sol-gel method with various Ni-Cu loading in the range of 0wt.% to 5wt.%. All prepared catalysts were characterized using Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), N2 adsorption-desorption, UV-vis diffuse reflectance spectrometer (UV-Vis-DRS), and Photoluminescence Spectroscopy (PL). The reaction was performed in a liquid-phase batch-reactor equipped with a UVC lamp (125W) as a source of UV radiation. The reactions were tested at atmospheric pressure and the temperature of 25 °C for 5 h with a catalyst loading of 4 g/L. It was found that the coating of bimetallic metal had effects on the reduction of surface area and energy bandgap. The prepared catalyst had a surface area in the range 108 m2/g to 199.6 m2 /g, and the bandgap energy varied from 3.01 eV to 3.08 eV. The presence of Ni (3wt.%) and Cu (2wt.%) on the TiO2/SiO2-Al2O3 catalyst had slower recombination rate of electron-hole pairs than that of TiO2/SiO2-Al2O3 catalyst. The highest methanol production rate of 405.08 µmol/gcat was obtained after 2 h over 3wt.%Ni-2wt.%Cu-TiO2/SiO2-Al2O3. This production rate was three times higher than that over unmodified TiO2/SiO2-Al2O3 due to good retardation of electron-hole pair recombination.
