Improvement of HZSM-5 performance by alkaline treatments: Comparative catalytic study in the MTG reactions

Modifying of Na-ZSM-5 zeolite catalyst applying converting of methanol to gasoline (MTG) was studied in this work. The post synthesis of HZSM-5 catalyst by CaCO3, Na2CO3 and NaOH solutions improved the catalytic performance to produce higher amount of gasoline range hydrocarbons. The catalyst samples were characterized by XRD, XRF, FT-IR, SEM and NH3-TPD techniques. The dehydration of methanol over synthesis catalysts carried out in a fixed-bed tubular reactor at 400 degrees C and WHSV of 28 h(-1) under ambient pressure. The desilication of the catalyst exhibited great improvements in catalytic life time, selectivity to C-5(+) hydrocarbons and yield of gasoline rang products. It was found that acidity of the sample treated by Na2CO3 more enhanced the catalytic performance among the other treated and untreated samples in the methanol to gasoline reactions. The yield of gasoline cut C-5(+) over this catalyst was increased about 43% in the mediocre time on stream (4 h), and also catalytic life time increased about 11.5% relative to HZSM-5 catalyst. (C) 2013 Elsevier Ltd. All rights reserved.