Methanol Dehydration to Dimethyl Ether over Silica Derived from Rice Husk as the Component-Based Catalysts

Dimethyl Ether (DME) an alternative fuel was synthesized by methanol dehydration over the silica-based catalysts. Silica extracted from both rice husk (A) and rice-husk ash (B) was used as the precursors for preparing the catalysts. The SiO2/Al2O3 and the SAPO catalysts prepared from that silica were analyzed using X-ray diffraction (XRD), N2 adsorption (BET surface area), X-ray fluorescence (XRF), NH3 temperature-programmed desorption (NH3-TPD), and thermal gravimetric analysis (TGA). The effects of reaction temperature on the methanol selectivity and conversion to dimethyl ether were investigated. The methanol dehydration reactions were carried out in a packed-bed reactor at the reaction temperature of 250-350°C. DME was the major product and formed with selectivity of 57% over SAPO-B. An increasing of the reaction temperatures resulted in the enhancing of methanol conversion. The highest methanol conversion of 93% was achieved at 325°C. The method of silica extraction had an effect on the selectivity to DME due to the higher BET surface area.