A kinetic study of catalytic combustion of ethyl acetate and benzene in air stream over Cr-ZSM-5 catalyst

Kinetic modeling of catalytic combustion of ethyl acetate and benzene over Cr-ZSM-5 (Si/Al = 240) is reported. Ethyl acetate was more reactive than benzene and could suppress benzene conversion in the binary mixture while water vapor retarded the conversion of both organics. Kinetic data obtained in the differential reactor at GHSV 78 900 h(-1) were best fitted by the Mars-van Krevelen model. In binary mixtures, a competitive model based on the Mars-van Krevelen mechanism satisfactorily predicted the ethyl acetate reaction rate. Ethyl acetate was more favorably adsorbed on the oxidized catalytic sites and could stabilize benzene by inducing an electron cloud from the aromatic ring. The inhibition effect by water was modeled by a competitive adsorption mechanism. Deviation in reaction rates at a feedwater concentration of 9000 ppm was attributed to the formation of water clusters that blocked the internal diffusion of VOC molecules. The oxidation/reoxidation steps of the active sites appeared to be the rate-limiting steps in the catalytic combustion of VOC over Cr-ZSM-5 catalyst.