POM-promoted synergistic catalysis of NO and chlorobenzene over amorphous MnCeOx catalysts: Activation of lattice oxygen, role of acid site, catalytic mechanism.

The release rate of lattice oxygen and surface acidic sites are key factors for the multi-pollutant synergistic catalysis such as nitrogen oxides (NOx) and chlorine-containing volatile organic compounds (Cl-VOCs). In this study, a polyoxometalate (POM)-assisted strategy was employed to optimize the synergistic catalytic performance of MnCeOx for NO and chlorobenzene. The strong proton conductivity of the surface POM structure effectively suppresses the deposition of chlorinated species, preventing the poisoning of active sites. Specifically, POM-SiW structure can act as a dechlorination site in place of Mn3O4 and exhibits the highest density of acidic sites and oxygen vacancies, leading to a reduction of the T90 for chlorobenzene to 167 ℃ and an expansion. The assistance of POM-SiW structure facilitates the electron transfer from POM-SiW to lattice oxygen (Olat), resulting in reduced orbital overlap between Mn and O atoms, thereby weakening the Mn-O bond and activating Olat. Furthermore, in-situ DRIFTs, TOF-SIMS and DFT results confirmed that POM-SiW structure can inhibit the competitive adsorption of NO, NH3 and chlorobenzene, NO2 and NH4+ act as additional oxidants and dechlorinating agents, effectively promoting the catalytic decomposition of chlorobenzene and its intermediate products. This work provides a novel strategy for catalyst design in low-temperature multi-pollutant synergistic catalysis.