Dehydration of 1,5-Pentanediol over CeO2-MeOx Catalysts

The dehydration reaction of 1,5-pentanediol was performed over CeO2 and modified CeO2 (CeO2-MnOx, CeO2-ZnO, CeO2-MgO, CeO2-CaO, CeO2-Na2O) catalysts in a fixed-bed tubular reactor at 350 degrees C and an atmospheric pressure. The undoped CeO2 produced a mixture of the products containing mainly 4-penten-1-ol, 1-pentanol, cyclopentanol, cyclopentanone and tetrahydropyran-2-one from 1,5-pentanediol, while additions of MgO, MnOx, or ZnO to CeO2 was found to enhance the overall production rate of unsaturated alcohol. On the other hand, more basic metals like CaO or Na2O tend to decline the dehydration activity of CeO2. The porous structure of CeO2 did not change appreciably with the addition of metal oxides. Temperature programmed desorption of adsorbed CO2 on an activated catalyst suggest more CO2 remain on the catalyst surface, particularly CeO2-CaO and CeO2-Na2O indicating that fewer defect sites are only available for reaction. The defect sites or oxygen vacancy on CeO2 controls both activity and selectivity for the dehydration of 1,5-pentanediol.