Mechanism of acrylonitrile decomposition over Cu-ZSM-5

The mechanism of acrylonitrile (AN) decomposition, that is, conversion of the nitrogen atoms in AN molecules to N2, over Cu-ZSM-5 was investigated. Oxygen was found to be necessary for AN decomposition and H2O in the reactant gas enhanced the reaction between AN and O2. The dependence of AN decomposition on contact time indicated that HCN, HNCO, NH3, and NOx behaved like intermediates. Temperature-programmed surface reaction of adsorbed AN revealed that H2O suppressed desorption of AN and lowered the temperature of N2 evolution. In situ diffuse reflectance infrared Fourier transform spectroscopy revealed that AN was mostly converted to isocyanate (–NCO), which was probably converted to adsorbed NH3 by hydrolysis. N2 was formed by the reaction of adsorbed NH3 and adsorbed nitrate or by oxidation of adsorbed NH3.

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