Upgrading Bio-oil: Simultaneous Catalytic Esterification of Acetic Acid and Alkylation of Acetaldehyde

This paper reports a simultaneous catalytic esterification of acetic acid and alkylation of acetaldehyde using a silica sulfuric acid catalyst from 40 to 140 °C. The results show that the esterification of acetic acid and acetalization of acetaldehyde with 1-butanol took place simultaneously, and both reactions were strongly affected by the temperature and catalyst dosage. The esterification of acetic acid was restrained by acetalization of acetaldehyde at a relatively low temperature (e.g., 90 °C). The increase of the reaction temperature, however, would result in the decomposition of acetals (1,1-dibutoxyethane). To solve these problems, 2-methyl furan, which can react with acetaldehyde, was introduced. Further work shows that the decomposition of 1,1-dibutoxyethane was successfully resolved by the alkylation reaction of acetaldehyde, and yields of the ester (butyl acetate) decreased with the increase of the water content. The maximum yields of alkylation products [2,2′-ethylidenebis­(5-methylfuran)] and butyl acetate were 84.5 and 74.4%, respectively.