Solar oxidation of toluene over Co doped nano-catalyst

Abstract

Cobalt (Co) co-doped TiO2 photo-catalysis were synthesized, characterized and tested toward solar photocatalytic oxidation of toluene (TOL). A multi-technique approach was used to characterize and relate the photo-catalytic property to photo-oxidation performance. Adding Co to TiO2 significantly changed crystal size and surface morphology (surface area, pore-volume, and pore size), reduced the bandgap energy of TiO2 and improved the solar photo-oxidation of TOL. Up to 96.5% of TOL conversion (%TNconv) was achieved by using Co–TiO2 compared with 28.5% with naked TiO2. The maximum %TNconv was achieved at high hydraulic retention time (HRT) ≥ 100 s, Co content in the photo-catalyst of 5 wt% and relative humidity (%RH) of 50%. The mechanism of TOL solar oxidation was related to the concentration of OH• and radicals produced from the generated electrons and holes on the surface of Co–TiO2. The products formed during the photo-catalytic oxidation of TOL were mainly CO2 and water, and minor concentration of benzene and benzaldehyde. Overall, the Co–TiO2 could be used as a potential photo-catalyst for the oxidation of toluene in gas-phase streams on an industrial scale.