Mn-Zr composite oxides for catalytic vinyl chloride oxidation: The deactivation and mechanism study

The catalytic stabilities of Mn-Zr composite oxides for catalytic oxidation of vinyl chloride (VC) were extensively investigated under variable catalytic systems and reaction temperatures. The physicochemical properties of fresh and spent catalysts, the formation of byproducts and the reaction intermediates were analyzed by various characterization methods and in situ approach with an aim of a better understanding about the deactivation origin and catalytic process. Characterization results indicated that the strong adsorption of residual chlorine species on the catalyst was the main reason for catalytic deactivation, concurrently inducing the byproducts formation of several chlorinated organics. With regard to the in situ DRIFTs analysis, the cleavage of C-Cl bond could occur under an inert atmosphere, but more tended to engender the formation of enolic and carboxylic acid species as the key organic intermediates under an oxygen condition.