Methanol Dehydration to Dimethyl Ether over Kaolinite-supported TiO₂ Catalysts

抄録

The present work aims to study the catalytic performance of kaolinite (KN)-supported TiO₂ in the production of dimethyl ether (DME) from methanol. KN was doped with 0, 3, 5, 10, and 15 wt% Ti composite particles via the sol-gel method. The performance of the TiO₂/KN catalysts were then tested in a fixed-bed reactor having a temperature in the range 200-350 °C under atmospheric pressure. The molar ratio of methanol to nitrogen, total gas flow rate, and weight hourly space velocity (WHSV) were set to 1:4, 60 mL/min at standard temperature and pressure, and 2.054 h^-1, respectively. The catalysts were characterized using scanning electron microscopy, the Brunauer-Emmett-Teller method, X-ray diffraction, and temperature-programmed desorption of NH₃. The final products were analyzed using gas chromatography. An increase in Ti loading yielded a higher methanol conversion rate owing to the increase in the number of acid sites on the catalyst surface. The highest methanol conversion rate of 79% was reported for TiO₂/KN (Ti=15%) at 350 °C. However, TiO₂/KN (Ti=15%) exhibited low selectivity to DME owing to the decomposition of DME to CH₄ and CO₂. Our results indicate the optimum Ti loading to be TiO₂/KN (Ti=10%), which resulted in a catalyst that was active at 250 °C and showed good selectivity to DME.