Influence of pretreatment and reaction conditions on the catalytic activity of HAlBEA and CoHAlBEA zeolites in vinyl chloride formation from 1,2-dichloroethane
Résumé
HAlBEA and CoHAlBEA zeolite catalysts treated at 523 K or 873 K for 3 h in Ar, H2/Ar or air flows, respectively, were investigated in catalytic dehydrochlorination of 1,2-dichloroethane (DCE). The dehydrochlorination of DCE on these zeolite catalysts resulted in almost 100% selectivity to vinyl chloride (VC) monomer. It was demonstrated that different conditions of pretreatment of zeolite catalysts resulted in varied amount of Lewis and Brønsted acid sites responsible of the catalytic activity, stability and selectivity. HAlBEA and CoHAlBEA zeolites treated in the Ar flow showed the best activities in the dehydrochlorination of DCE, while the same zeolites treated in the air flow demonstrated the best time-on-stream stability. To clarify the reasons of differences in the catalytic behavior of HAlBEA and CoHAlBEA treated in the various conditions N2 physisorption, XRD, TPH, TEM, XPS, NMR and FTIR measurements were performed.