Intrinsic reaction kinetic study for catalytic dehydration of methanol to dimethyl ether

A series of mixed metal oxide (MMO) solid-acid catalysts were synthesized for methanol dehydration to dimethyl ether reaction. These catalysts were prepared via the wet impregnation method by modifying γ-Al₂O₃ with varying contents of molybdenum, phosphorus, and magnesium. The influence of compositional variation on catalytic performance was systematically studied to identify the optimum catalyst. The catalysts were comprehensively characterized using BET, XRD, NH₃- TPD, elemental analysis, SEM and HR-TEM. Among the series, the optimized MMO-3 catalyst (90 wt% Al₂O₃, 5 wt% P, 3 wt% Mo, and 2 wt% Mg) exhibited conversion of 86.9% and selectivity of 100%. Intrinsic kinetic studies were carried out on the MMO-3 catalyst under differential reactor conditions, ensuring the absence of mass and heat transfer limitations. These reactions were conducted in a fixed-bed reactor under atmospheric pressure across a temperature range of 200–280°C at a weight hourly space velocity (WHSV) of 1- 12 h⁻¹, while varying the feed concentration of methanol with water. A new semi-empirical rate expression was developed in this study, which provided the best fit to the experimental data. The estimated activation energy is 65.91 kJ. mol -1 . These results highlight the moderate energy barrier for methanol activation and demonstrate that the laboratory-synthesized MMO-3 catalyst exhibits better performance as compared to commercially available catalysts. This enhanced catalytic performance makes MMO-3 a catalyst for reliable kinetic modelling and future process scale-up.