One-pot Aldol Condensation and Hydrodeoxygenation of Biomass-derived Carbonyl Compounds for Biodiesel Synthesis

Integrating reaction steps is of key interest in the development of processes for transforming lignocellulosic materials into drop‐in fuels. We propose a procedure for performing the aldol condensation (reaction between furfural and acetone is taken as model reaction) and the total hydrodeoxygenation of the resulting condensation adducts in one step, yielding n‐alkanes. Different combinations of catalysts (bifunctional catalysts or mechanical mixtures), reaction conditions, and solvents (aqueous and organic) have been tested for performing these reactions in an isothermal batch reactor. The results suggest that the use of bifunctional catalysts and aqueous phase lead to an effective integration of both reactions. Therefore, selectivities to n‐alkanes higher than 50 % were obtained using this catalyst at typical hydrogenation conditions (T=493 K, P=4.5 MPa, 24 h reaction time). The use of organic solvent, carbonaceous supports, or mechanical mixtures of monofunctional catalysts leads to poorer results owing to side effects; mainly, hydrogenation of reactants and adsorption processes. One step is enough! The use of bifunctional catalysts allows the integration of aldol condensation and total hydrodeoxygenation of the condensation products in a single step. Using an aqueous solution of furfural and acetone, selectivities to alkanes higher than 50 % are obtained when Pt/Mg–Zr oxides are used as catalyst. The use of organic solvent, carbonaceous supports, or mechanical mixtures of basic and metal catalysts leads to poorer results.