Photocatalytic oxidation of thiophene on RuO2/SO42−-TiO2: Insights for cocatalyst and solid-acid

• Highly efficient photocatalytic oxidation of thiophene was achieved on solid acid SO42−-TiO2 loaded with cocatalyst RuO2.
• The synergistic effect between oxidation catalysis and acid catalysis is crucial for developing highly active photocatalysts.
• The characterization shows that the crystallinity and surface acidity property of TiO2 is greatly improved by sulfation process.

Thiophene is one of the main sulfur-containing compounds present in gasoline and difficult to be oxidized with the conventional oxidative processes. Photocatalytic oxidation is believed to be a promising way to remove the sulfur-containing compounds from gasoline. Here we studied the photocatalytic oxidation of thiophene on RuO2/SO42−-TiO2 photocatalyst. We found that high activity can be achieved on 0.045 wt.% RuO2/1 M SO42−-TiO2 using molecular oxygen as oxidant. The sulfur in thiophene is oxidized to SO3 finally. SEM and XRD measurements show that the crystallinity of TiO2 is greatly improved by sulfation process. IR spectra of pyridine adsorption measurements gives the evidence for that the surface acidity property of TiO2 is also greatly improved. We can conclude that the synergistic effect of RuO2 acting as an oxidation cocatalyst and SO42−-TiO2 acting as a Lewis acid which capture superoxide species/activate thiophene molecules is responsible for the activity enchancement of thiophene photocatalytic oxidation. The synergistic effect between oxidation catalysis and acid catalysis is crucial for developing highly active photocatalysts for environmental protection.

Figure optionsDownload as PowerPoint slide