Simultaneous removal of naphthalene and NOx over V-Ce/Ti catalyst: Design of separated active sites for naphthalene degradation and SCR reaction

V-Ce/Ti catalysts were prepared for the removal of naphthalene and NOx in the flue gas. The adverse effects of NH3 and NO on the naphthalene degradation were weakened on V-Ce/Ti, resulting in a decrease of only 2.5% in COx selectivity. The formation of high molecular weight byproducts was also reduced. Besides the acid sites on the catalysts, Ce introduced new Brønsted basic sites, which could also adsorb and degrade naphthalene into naphthol effectively. With the separated active sites for naphthalene degradation and NO removal, the reaction between NH3 and the intermediates during the naphthalene degradation was also inhibited, decreasing the formation and accumulation of phthalimide. The oxidation of the intermediates was promoted by active V5+ introduced by Ce, inhibiting the transformation of the intermediates to higher molecular weight byproducts. Nearly 100% conversion of naphthalene and NO, as well as 40.1% of the COx selectivity were obtained on V-Ce/Ti. Nowadays, there is relative high amount of polycyclic aromatic hydrocarbons (PAHs) been emitted from the flue gas of coal-fired power plants, which brings significant threat to human health and ecosystems. The simultaneous removal of PAHs and NOx in selective catalytic reduction (SCR) devices is an economically feasible solution. In our research, V-Ce/Ti catalyst with separated active sites for both SCR reaction and PAHs degradation were synthesized, which demonstrated an ideal performance in efficient removal of PAHs and NOx. Moreover, the reaction mechanism for the simultaneous removal of PAHs and NOx over V-Ce/Ti was studied by in situ DRIFTS.