Anti-carbon deposition performance of twinned HZSM-5 encapsulated Ru in the toluene alkylation with methanol

摘要

Toluene methylation with methanol to produce para-xylene has been extensively and intensively studied.However,the methanol-to-hydrocarbons(MTH)side reaction in this reaction is difficult to be inhibited,which will cause a mass of carbon deposition and cover the catalyst surface,resulting in catalyst deactivation.Here,a dual-functional Ru@HZSM-5 catalyst with high para-selectivity and low carbon deposition was prepared by encapsulating Ru metal with HZSM-5.According to catalytic performance studies,the Ru@HZSM-5 catalyst produced xylene selectivity of 98%and para-xylene selectivity of 96%.Meanwhile,we find that carbon precursors(e.g.ethylene)were very little when Ru catalyst was used,but the results of HZSM-5 catalyst were completely opposite.Ru@HZSM-5 catalyst achieves a lower carbon deposition rate of only 6%of HZSM-5.The main possible reason for this is that the initial C-C bond between methanol and the olefin is difficult to form.