The gas phase dehydration of ethanol over gamma-alumina catalyst to produce ethylene was investigated in a tubular fixed bed reactor. The feed of 93.7 weight percent of ethanol was used throughout the experiments.
Kinetics of formation of ethylene and ether were experimentally studied in continuous operation with gamma-alumina catalysts (3/16"×1/8" pellet) in the reaction temperature range of 300℃ to 375℃ and liquid feed rate of 0.041 cc/sec to 0.321 cc/sec. The reaction system was composed of three reactions; the dehydration of ethanol to ethylene, the reaction of ethanol to form ether, the dehydration of ether to ethylene. The rates of formation of ethylene from ethanol and ether were found to be first order and that of ether from ethanol was second order with respect to reactants' concentrations in gas phase, respectively.
Cyclic operation were performed by on-off control of liquid flow rate in order to see whether conversion of ethanol and yield of ethylene were improved. The effect of cycle time was investigated in the cycle time ranges of 1 sec to 3.2 sec at two different amplitude ratios of two and three times of the average flow rate of 0.134 cc/sec. Reaction temperature was kept constant at 325℃. Maximum conversion of ethanol was 72.35 percent when amplitude ratio was two and cycle time 1.6 sec, and maximum yield of ethylene was 41.84 percent when amplitude ratio was two and cycle time 1 sec, while conversion of ethanol was 67.50 percent and yield of ethylene was 37.20 percent in continuous operation under the same reaction condition.
