The ethanol dehydration over alumina-spherical silica particle composite catalyst from modified sol-gel method

The spherical silica particle (SSP) and alumina silica composite (Al-SSP) catalysts were investigated for catalytic properties and catalytic activity via dehydration of ethanol. The SSP and Al-SSP catalysts were prepared by modified sol gel method with various alumina content ranges from 20 to 80 mol%. The properties of these catalysts were characterized by TGA, SEM, XRD, FTIR, EDX, XRF, NH3-TPD and nitrogen physisorption. In the first part, the dehydration of ethanol in gas phase over SSP and Al-SSP catalysts was performed in a fix-bed reactor at the atmospheric pressure with various temperatures from 200 to 400 ºC. The 60Al-SSP catalyst exhibited significantly higher acidity than the others. The ethanol conversion and selectivity depend on alumina content and reaction temperature. At lower temperature, diethyl ether was produced in significant quantities, while at higher temperature, ethylene was the major product. It was found that the 60Al-SSP exhibited the highest ethanol conversion and ethylene selectivity. The next part, it was found that the increasing of water content in reactant led to the increasing of ethanol conversion and ethylene yield at high temperature. However, it remains below the ethanol conversion and ethylene yield of pure ethanol. In the last part, the performance of 60Al-SSP via time on stream (TOS) test for 10 hours was investigated. The results showed that the conversion of ethanol and ethylene yield of pure ethanol kept constant at high during 10 hours, while the conversion and the ethylene yield of bioethanol slowly increased. And the coke formation on 60Al-SSP catalyst with using pure ethanol was higher than bioethanol.