Synthesis of 1-Butanol from Ethanol over Calcium Ethoxide: Experimental and Density Functional Theory Simulation
2019
Wang, Dong | Liu, Zhenyu | Liu, Qingya
Conversion of bioethanol to 1-butanol has attracted much interest in the field of renewable resource conversion. Development of efficient catalysts is a hot topic for this reaction. In this work, calcium ethoxide was evaluated for ethanol condensation in a batch reactor. Results show that ethanol conversion is about 25% at 275–300 °C in 8–10 h, with 1-butanol and total alcohol carbon yields of 11% and 22%, respectively. The carbon balance shows that acetaldehyde is an intermediate of the reaction. Density functional theory (DFT) simulation confirms the intermediate and indicates that the promoting role of calcium ethoxide originates from the adsorption of O atom in ethanol on the Ca atom of calcium ethoxide, which activates the ethanol to form the adsorbed acetaldehyde and activated H. The adsorbed acetaldehyde reacts with ethanol to form 2-butenol via the aldol condensation while the 2-butenol is hydrogenated by the activated H to form 1-butanol. For the aldol-condensation reaction, ethanol and acetaldehyde prefer adsorbing on the same calcium ethoxide molecule to adsorbing on adjacent two calcium ethoxide molecules. The highest energy barrier of the former route for ethanol dehydrogenation is 288 kJ mol–¹ while that of the latter route for 2-butenol formation is 319 kJ mol–¹.
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