Catalytic conversion of methanol to aromatics over bimetallic CuO-ZnO/ZSM-5-ZSM-11

Methanol to hydrocarbon process is becoming increasingly important as methanol can be manufactured from flare gas, biomass, shale gas and coal [1]. In this work, composite co-crystalline zeolites ZSM-5-ZSM-11 synthesized by hydrothermal method [2], Then this nanocomposite catalyst modified with (2 wt %) Zn - (1 wt %) Cu by direct synthesis procedure and characterized by means of techniques such as XRD, SEM, TEM, N2 adsorption– desorption, XRF, NH3-TPD and FT-IR. The results indicate that metal species were successfully incorporated into ZSM-5- ZSM-11 zeolites. The obtained results showed after substitution of the framework Al by metal species crystal size and average diameters decrease while surface area and pore volume increase. The catalytic performances of prepared nanocrystalline zeolites were investigated by methanol to gasoline (MTG) reaction in a fixed bed stainless-steel reactor to study the synergistic effect of CuO and ZnO. The results indicated that the addition of ZnO promoted the catalytic activity of CuO in methanol aromatization to aromatics [3]. The NH3-TPD results imply that the incorporated Cu and Zn species replaced parts of the conventional acid sites and formed some new acid sites in the zeolites. This new acid sites significantly improved the hydrogen transfer and aromatization reaction, increasing the yield of aromatics.The catalytic results illustrated that the methanol conversion was higher than 90% for about 60 h, meanwhile, the gasoline yield reached up to 44%.