Catalytic combustion of vinyl chloride over Sr doped LaMnO3

Active Sr substituted LaMnO3 perovskite type catalysts were prepared by sol-gel method and further modified by acid, and the catalytic activity for vinyl chloride (VC) combustion were investigated. The techniques of XRD, N-2 adsorption-desorption, H-2-TPR, XPS were employed for the catalyst characterization. The HCl modified La0.5Sr0.5MnO3 (L0.5S0.5MO -H) showed the highest activity under stable test condition, VC could be completely converted to CO2 at 300 degrees C, and the main chloric organic by-products were trichlormethane (TCM), tetra-chloromethane (CTC) and 1,1,2-Trichloroethane (TCE), and their concentration were all below 5ppm. The characterization results showed that the pretreatment obviously promoted the amount of the active Mn4+ species and oxygen activation ability. The oxidation capability greatly affected the chloric by-product distribution, for the difference in oxidation capacity made the formation of chloric by-products followed different pathways. The lower temperature for VC complete oxidation would inhibited the Deacon reaction and chlorination occurred. However, the strong basicity of Sr and the preference to form Sr-Cl bond were inclined to keep Cl species on Sr and made active Mn species free of Cl.