Reaction Steps in Heterogeneous Photocatalytic Oxidation of Toluene in Gas Phase—A Review

A review of the current literature shows there is no clear consensus regarding reaction mechanisms air-borne aromatic compounds such as toluene by photocatalytic oxidation. Potential oxidation reactions over TiO2 or TiO2-based catalysts under ultraviolet and visible (UV/VIS) illumination are most commonly considered for removal these pollutants. Along pathways from a model pollutant, toluene, to final mineralization products (CO2 H2O), formation several intermediates via specific include parallel less-reactive on surface. The latter may occupy active adsorption sites causes drastic catalyst deactivation in some cases. Major hazardous gas-phase benzene formaldehyde, classified International Agency Research Cancer (IARC) Group 1 carcinogenic compounds. Adsorbed leading benzaldehyde, benzoic acid, cresols. three typical reviewed: methyl group oxidation, ring opening.