Micro-kinetic modelling of photocatalytic CO2 reduction over undoped and N-doped TiO2
CO2 photoreduction is studied using in-house synthetized undoped and N-doped TiO2 nanoparticular photocatalysts. Comparison with the commercial P25 TiO2 powder shows that the synthetized samples are more effective. P25 produced a negligible amount of CH4, unlike the synthetized samples. N-doping of TiO2 powder caused higher productivity rate of all product, and provided the best performance for CO2 reduction. The average production rate of CH4 was 0.191 μmol h-1 g-1, whereas of CO was 0.111 μmol h-1 g-1. The experimental data is used to fit the micro-kinetic modelling parameters. The kinetic constant of H2O dissociation is the lowest for all tested samples, showing that this is the rate-determining step. The kinetic constants for the H2, CO, and CH4 formation were of the same order for all catalysts samples, showing that the rates of these reactions are independent on the catalyst type.