Influence of the synthesis route on the catalytic oxidation of 1,2-dichloroethane over CeO2/H-ZSM5 catalysts

Abstract

The performance of supported CeO₂/HZSM-5 catalysts with a nominal CeO₂ loading of 10 wt.% was evaluated for the oxidation of one of the most common chlorinated pollutants found in waste streams, namely 1,2-dichloroethane. The influence of the preparation method, such as impregnation in different media (water and ethanol), precipitation and ion exchange, was examined. Structural, morphological and physico-chemical changes caused as a function of the synthesis procedure were analysed by atomic emission spectroscopy, X-ray diffraction, BET measurements, transmission electronic microscopy, X-ray photoelectron spectroscopy, NH₃-temperature- programmed desorption, adsorption of CO at low temperature followed by infrared spectroscopy, temperature-programmed reduction with hydrogen, energy dispersive X-ray spectroscopy and dynamic thermogravimetry coupled to mass spectrometry. The enhancement of the catalytic behaviour of the resulting ceria loaded samples with respect to plain H-ZSM5 could be explained on the basis of the synergetic effects of oxygen mobility and acid sites. In particular, the procedure based on impregnation with ethanol led to a highly dispersed ceria catalyst with a larger amount of oxygen vacancies. As a result, this catalyst required a temperature lower than 200 °C for attaining 50% conversion.