Catalytic conversion of methanol to gasoline range hydrocarbons

The catalytic conversion of methanol to hydrocarbons of gasoline range has been studied over HZSM-5, ZnO/HZSM-5, CuO/HZSM-5 and CuO/ZnO/HZSM-5. The selectivity of methanol conversion to hydrocarbon has been found to be a function of CuO/ZnO/HZSM-5 concentration. A comparison has been done to study the conversion and yield of different metal oxides doped on the catalyst. The catalysts were prepared by means of impregnation technique followed by heat treatment at 550 degreesC for 5 h. The copper and zinc oxide loading over HZSM-5 (Si/Al = 45) catalyst were 7 wt.% each. These catalysts were characterized by X-ray diffraction and surface area analysis. The performances of the catalysts were evaluated by conducting experiments in a fixed bed reactor (i.d.: 19 mm) made of stainless steel. Experiments were conducted at 1 atm and 400 degreesC at constant flow rate of methanol. The major products were ethylene, propylene, dimethyl ether, toluene, ethyl benzene, ethyl toluene, trimethyl benzene and tetra methylbenzene. Investigations have also been done to study the catalyst deactivation. The catalysts were mainly deactivated due to deposition of coke. Addition of ZnO over CuO/HZSM-5 significantly reduces the coke without affecting product yields. Over a ZnO/HZSM-5 catalyst, the coke formation was reduced compared to a CuO/HZSM-5 catalyst. ZnO/CuO/HZSM-5 enhanced the aromatics yield to 69 wt.% as compared to yield of 66.9 wt.% over ZnO/HZSM-5. The product compositions are compared and discussed. (C) 2004 Elsevier B.V. All rights reserved.