LAUSR

Abstract In the present work, the photocatalytic treatment of simulated automotive exhaust emissions was studied in an annular reactor operating in CSTR mode. Three feeds with different compositions were created, rich (λ = 0.98), stoic (λ = 1), and lean (λ = 1.02) and five photocatalysts were tested: TiO 2 isopropoxide, TiO 2 P25 and TiO 2 -P25 with addition of 1% of Pt, Fe or Ce. Pt-TiO 2 P25 showed the highest activity for NO and hydrocarbons (C 3 H 6 , C 3 H 8 ) removal, with hydrocarbons oxidation being promoted in lean conditions of feed and NO reduction in rich condition of feed, behavior similar to commercial three-way catalysts. Additional work was carried out in order to study separately the main reactions that take place on the catalytic surface. For NO decomposition/oxidation reaction in the presence of water there was no NO 2 formation observed and also no deactivation of the catalyst which indicates that decomposition reaction is the main reaction with good selectivity to N 2 formation for these conditions. In C 3 H 6 oxidation the increase of O 2 inlet concentration leads to the increase of the reaction rate and in redox reaction of NO with C 3 H 6 the results showed that a secondary reaction for C 3 H 6 is required to explain the conversion values. The kinetic study of the reactions showed that Langmuir–Hinshelwood expression can interpret the experimental data assuming that NO and C 3 H 6 are co-adsorbed on the same active sites, with dissociatively adsorption of C 3 H 6 and O 2 adsorption on different active sites.