Performance of Al-MCM-41 nanospheres as catalysts for dimethyl ether production

Abstract The need to develop specific-morphology nanomaterials to produce dimethyl ether (DME), a promissory alternative fuel, by the catalytic methanol dehydration has triggered extensive research to synthesize novel materials. In this work mesoporous Al-MCM-41 nanospheres with variable size (35-90 nm) were synthesized by the sol-gel method. The size of the Al-MCM-41 nanospheres was controlled by adjustable NaOH/TEOS ratio (0.2-0.5). The Al-MCM-41 nanospheres were characterized by TPD, TEM, XRD, EDX, XPS and N2-physisorption. According to the characterization results the Al ions were successfully incorporated in the MCM-41 framework and the Al-MCM-41 nanospheres showed hexagonal and mesoporous structure. Additionally, it was observed that the higher the NaOH/TEOS ratio the smaller size of the nanosphere and, smaller Al-MCM-41 nanospheres presented more amount of medium acidic sites on its surface. The catalytic activity results showed that all samples tested reached 100% of selectivity towards DME. The smallest Al-MCM-41 nanospheres achieved 78 % of DME yield at 300 °C and good catalytic activity performance below to 300 °C. The stability of the fresh and regenerated Al-MCM-41 nanospheres was evaluated for 48 h time-on-stream. High values of DME yield (> 60 %) were maintained during 48 h time-on-stream showing the possibility for recycling the material.