The influence of the Si/Al ratio of Mo/HZSM-5 on methane non-oxidative dehydroaromatization
A series of Mo/HZSM-5 catalysts with Si/Al ratios ranging from 16 to 136 were prepared. The physico-chemical properties of the catalysts were characterized by XRD, H2-TPR, NH3-TPD, Py-IR and so on. The catalytic performance was tested in methane non-oxidative dehydroaromatization. The results showed that the anchoring mode between molybdenum species and HZSM-5 changed with the increase of the Si/Al ratio, with MoO22+ for the low Si/Al ratio samples and (Mo2O5)2+ for the high Si/Al ratio samples. This would also influence the dispersion of Mo species at the external surface or inner channel of the HZSM-5 zeolite. Besides, the post-reaction catalysts for various Si/Al ratio samples were also characterized. Both the coke deposits generated at the external surface and in the zeolite channels could deactivate the catalyst, but the former might contribute more than the latter. BAS could resist the coke at the external surface and induce excellent performance.