Enhanced ethylene production by dehydration of ethanol over Al/SBA-15 mesoporous catalysts

Abstract

Dehydration of ethanol into ethylene was studied over Al/SBA-15 at the temperature range 250–450 °C. A novel technique was developed for synthesis of three kinds of Al/SBA-15 as mesoporous catalysts by modifying the reported direct and post synthesis procedures. The neat SBA-15 as well as Al/SBA-15 were characterized adopting several characterization techniques viz., N2 adsorption–desorption, XRD, TGA–DSC, FT-IR, TEM, EDX and NH3-TPD. Incorporation of Al into modified SBA-15, namely, Al/SBA-15(Inst), prepared by in situ Al grafting direct method, could result in a marked acidity referred to the presence of stronger Bronsted acid sites and an increased surface area (880 m2/g) reflecting on the catalyst functionality. As a consequence, this Al–SBA/15(Inst) catalyst sample exhibited the highest activity toward ethylene production with a maximum yield of (100%) at 400 °C. The percent ethanol conversion at the same reaction temperature decreased on the studied catalysts in the order: Al–S(Inst) prepared by in situ direct modification > Al–S(Imp) produced by impregnation post synthesis > Al–S(Us) obtained through ultrasonic irradiation > neat SBA-15. All the modified catalysts achieved 100% selectivity which was stabilized over the whole temperature range used. They may be considered thus as highly promising candidates for selective ethanol dehydration into ethylene.