Synthesis promotion and product distribution for HZSM-5 and modified Zn/HZSM-5 catalysts for MTG process

Abstract

In this study presented here, attempt is made to development of active zeolite base catalyst for gasoline production in methanol to gasoline (MTG) catalytic process based on wet impregnation technique. Synthesis and improvement methods for ZSM-5 zeolite are essential for a wide variety of different reactions in the chemical industry. In this regard, HZSM-5 and promoted Zn/HZSM-5 samples are prepared. HZSM-5 is synthesized by NaOH treatment and then it is promoted using wet impregnation technique. Distribution of hydrocarbons, which produced in catalytic reaction of methanol to gasoline process, are reviewed over synthesized HZSM-5 and promoted samples with Zinc (Zn) element in a fixed-bed continuous flow reactor. The reaction is performed with weight hourly space velocity (WHSV) equal to 4 (gmethanol)·(gcatalysth)−1, at ambient pressure and 370°C. The zeolite samples after preparation are characterized by XRD, SEM, TPD-NH3 and N2 adsorption/desorption isotherms tests. We have finally managed to identify optimized Zn impregnated catalyst (Zn/HZSM-5) that is exhibited good improvements in liquid hydrocarbons production compared to other prepared samples. Optimized sample is prepared with Zn loading equal to 0.75wt.%. For optimized sample, the results showed that in gas phase, produced C5+ component is increased; in addition, produced dimethyl ether and unreacted methanol are decreased compare to other prepared samples. Also in liquid phase, produced xylene and alkyl aromatic components are increased about 9.33%; in addition yield of produced hydrocarbons (produced gasoline) are increased. Also, 30% increase in the weight of oil cut over optimized sample is observed.