Ni-doped high silica HZSM-5 zeolite (Si/Al = 200) nanocatalyst for the selective production of olefins from methanol

摘要

This study deals with the modification of high silica H-ZSM-5 zeolite by different transition metals (nickel, iridium and silver). The nanocatalysts were characterized by XRD, FE-SEM, FT-IR, NH3-TPD, Pyridine adsorption IR spectra (Py-IR) and N-2 adsorption-desorption. The metal (0.5 wt.%) was introduced by wet impregnation technique including multi-steps. The promoter species were uniformly distributed on the nanocatalyst without significant damage of the structure. The nickel impregnation resulted in the high crystallinity (97.2%) and well adjusted acidity (strong/weak acidity = 0.98). The results showed that the nickel impregnation not only modulated the concentration of acid sites but also regulated the acid type. The highest methanol conversion (99.9%), light olefins selectivity (84%) and the lowest C5+ selectivity ( 10%) showed the high efficient performance of the nickel-doped ZSM-5 nanocatalyst in methanol to olefin (MTO) reaction for long time on stream.