Effect of the P/Al ratio on the performance of modified HZSM-5 for methanol dehydration reaction

The precipitation method was used to modify HZSM-5 by coating it with aluminophosphate at P/Al molar ratios of 0.3, 0.8, 1.2 and 1.5. These catalysts were characterized by XRD, NH3-TPD, BET, FT-IR, ICP-TEOS and SEM and evaluated as catalysts for the methanol dehydration reaction. The ZALPO0.8 catalyst achieved 86% conversion which was the highest conversion till 315 °C. It was found that primary benefits of AlPO modification were that it tended to retard the activity of the highly active acid sites which promote dimethyl ether decomposition and led to decrease in the apparent activation energy.