The ethanol dehydration was performed over a commercial alu- mina based catalyst, which had exhibited 97.7% ethylene selectivity at 99.9% ethanol conversion during the catalyst screening experi- ments at temperature 400 ◦ C. The original catalyst was in the form of cylinder with a height of 5–6 mm and a diameter of 3.6–4.0 mm.
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doi:10.1016/j.cej.2011.06.049
The BET surface area of the catalyst was 270 m2 /g. In kinetic experi- ments the catalyst was crushed to the size of 0.25–0.5 mm particles to avoid intraparticle diffusion limitations and create kinetics- controlled conditions.
The steady-state kinetics of ethanol dehydration to ethylene has been studied experimentally in a differentially operated reactor at
normal pressure and temperature interval of 350–450 ◦ C. The com-
position of inlet reaction mixture was (mol.%): ethanol 41.3–78.8, water 12.8–50.8, and nitrogen–balance. The residence time was within 0.005–2.2 s. The influence of reagent concentrations, res- idence time and operation temperature on the rate of ethylene formation and product selectivities has been studied. The exper- imental conditions secured no mass and heat transfer limitations. The catalyst activity as well as the reproducibility of the measure- ments was regularly checked by performing a standard experiment at the same conditions.
The experimental studies revealed that the main products of the ethanol dehydration on the surface of alumina-based catalyst are ethylene, acetaldehyde (ACA), diethyl ether (DEE) and butylenes, according to the following reaction scheme: