STABILITY OF MIXED-PHASE ALUMINA CATALYSTS FOR ETHANOL DEHYDRATION REACTION

Abstract

Dehydration reaction is an important and basic technology for converting ethanol into ethylene product which temperature is less than pyrolysis reaction. It is also considered as alternative energy for future. Many researches improve and modify catalyst in order to obtain high selectivity. The selectivity factor mostly depends on acidity on a catalyst and temperature, which is catalytic early degradation. In this present study, the mixed gamma and chi crystalline phases of alumina catalyst calcined at 600 °C was employed for ethanol dehydration to ethylene. The mixed γ- and χ-crystalline phase alumina was prepared by solvothermal method. The catalyst was performed for ethanol dehydration reaction under atmospheric pressure at temperature of 200-400 °C in a fixed-bed reactor. They exhibited both high conversion and high selectivity to ethylene more than 90% of interval temperature 350-400°C. The catalyst was characterized by several techniques. However, the stability of these catalysts will be further investigated by reaction test at the specified temperature (300-400°C) within time-on-stream (TOS) around 6 and 12 hrs.. The coke formation will appear on the surface of spent catalysts. After TOS 12 hrs., the coke content reaches very high level, which affects to catalyst deactivation. Therefore, the operating condition (such a TOS and temperature) leads to generate coke deposited on the catalysts significantly. The different characteristics of the fresh and spent catalysts will be compared and discussed further. Moreover, the modified MoO3 loading on mixed γ- and χ-crystalline phase alumina catalysts were investigated catalytic performance at the same condition of TOS in order to study effective of metal oxide and compare with mixed phase alumina catalysts for predicable the optimum temperature.