Differences of Short Straight-Chain Monoalcohols in the Value-Added Conversion of Furfural Catalyzed by Zr3Al1-MMO: Effect of Hydroxyl Position and Carbochain Length

We synthesized a catalyst of zirconium–aluminum bimetallic oxides (Zr3Al1-MMO) by microwave and investigated the effect of alcohol solvents on furfural valorization. Zr3Al1-MMO had high catalytic activity under mild conditions (80–140 °C). The hydroxyl position of the alcohol sources had a decisive influence on the reaction type. Furfural would condense with the primary alcohols to form high-carbon compounds, and the secondary alcohols prefer to act as a hydrogen donor to promote the transfer hydrogenation process to produce furfuryl alcohol. As the length of the carbon chain of alcohol solvent increased, both types of reactions showed a decrease in yield, which can be attributed to solvent polarity and steric hindrance. Reaction kinetics results verified the above conclusions. Combined with characterization results, we believed that the acid–base sites provided by the zirconium, aluminum, and oxygen vacancies in the catalyst were the main active sites. Through stability and recyclable experiments, Zr3Al1-MMO further confirmed its potential for industrial applications.