PROMOTION OF SELECTIVE CONVERSION OF METHANOL TO XYLENES OVER TRIMETALLIC & ALKALINE-LOW-Si/Al ZSM-5

PROMOTION OF SELECTIVE CONVERSION OF METHANOL TO XYLENES OVER TRIMETALLIC & ALKALINE-LOW-Si/Al ZSM-5

In the current communication, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over mesoporous low-silica ZSM-5 (Si/Al = 11) catalysts while the promotional effect of Zn and Fe was also explored. The catalyst was prepared by employing alkaline treatment of the parent ZSM-5 (alk-ZSM-5) prior to impregnation with Fe and Zn. The catalyst samples were characterized by using XRD, XRF, NH3-TPD, SEM, TGA, FT-IR techniques. On the basis of TPD analysis, the incorporation of Zn into ZSM-5 adjusted the acidity to notable strong/weak ratio of 2.1. The parent ZSM-5 and [Fe, Zn]-alk-ZSM-5 catalysts were hired for the conversion of methanol to gasoline (MTG) process. The dehydration of methanol over catalysts carried out in a fixed-bed tubular reactor at 375 °C and WHSV of 1.9 h-1 under ambient pressure. The trimetallic catalyst [Fe, Zn]-alk-ZSM-5 exhibited great improvement in selectivity for aromatic hydrocarbons on the basis of GC and GC-MS results. [Fe, Zn]-alk-ZSM-5 catalyst was capable to promote the formation of 86.8 wt.% aromatics with highly selective for xylenes selectivity (44.7 %) having very low content of benzene (0.1 %). Both of the catalysts enjoy of long-term activity, e.g. keeping ~96% of their activity after 8 h.