Vanadium-titanium catalysts are commercially deployed for selective catalytic reduction (SCR) of industrial NOx emissions. However, their performance in complex flue gases containing NOx, aromatic volatile organic compounds (VOCs, e.g., toluene), and chlorinated VOCs (e.g., chlorobenzene) remains limited. This study evaluates the crystalline phase-dependence of TiO2-supported V2O5 catalysts (anatase: V/TiO2-A; rutile: V/TiO2-R) for synergistic multipollutant control. We identify a crystal-dependent reversal in synergistic catalytic performance: V/TiO2-A exhibits superior activity for NOx-toluene coremoval, while V/TiO2-R achieves optimal NOx-chlorobenzene elimination. Mechanistic studies reveal that oxygen vacancies in V/TiO2-A enhance toluene activation, whereas high V5+/V4+ ratios and Brønsted acidity in V/TiO2-R promote chlorobenzene activation and HCl formation. This insight enabled the design of a tandem catalyst system (V/TiO2-R upstream + V/TiO2-A downstream) within a single SCR reactor, achieving >90% simultaneous conversion of NOx, chlorobenzene, and toluene at 375 °C─outperforming individual catalysts, physical mixtures, and commercial benchmarks with high HCl selectivity. The configuration exploits phase-specific strengths─rutile for chlorinated VOC oxidation at high temperatures, followed by anatase for aromatic VOC degradation─avoiding separate control units and easing retrofit cost and space constraints.
Liu et al. (Thu,) studied this question.