5. Conclusions
In this work the process of bioethanol dehydration to ethy- lene over alumina-based catalyst has been studied at multiscale approach, viz. kinetic studies, pilot reactor testing, and process simulation. Kinetic studies were carried out in a differential reac- tor over alumina-based catalyst at normal pressure and within the temperature interval of 370–450 ◦ C. It was determined that forma- tion of ethylene occurs through the parallel-consecutive reaction scheme – directly from ethanol and via intermediate DEE. The maximal ethylene selectivity is achieved if the concentration of ethanol in inlet reactant mixture is no less than 94 wt.% and the temperature range of the process is within 370–400 ◦ C. For both the ethylene and by-products formation steady-state reaction rates were determined over a wide range of operation temperatures and inlet reagent concentrations. The observed reaction rates and acti- vation energies for the ethylene and the by-products reaction rates correspond well with the data obtained from kinetic model. Kinetic model with obtained parameters was used for the process simula- tion in industrial reactor of ethylene production.
An experimental study was presented on the performance of ethanol dehydration in a pilot set-up with a single-tube reactor. The influences of the thermostat temperature, gas flow rate, and residence time in the catalyst bed were experimentally examined and compared with the results obtained from numerical simu- lations. From pilot reactor study it was found that the lowest index of ethanol/raw ethylene consumption C = 1.7 kg/kg can be achieved when ethanol conversion is no less than 98% and ther- mostat temperature does not exceed 440 ◦ C. The catalyst exhibited
good performance and stability in pilot experiments. With the vali- dated model of a single tube reactor and using the minimal number of tubes as the optimization criterion, the optimal characteristics and process parameters of industrial tubular fixed bed reactor for ethylene production from bioethanol at capacity 60,000 TPA have been determined.