Performance of bifunctional Pd/MxNyO (M = Mg, Ca; N = Zr, Al) catalysts for aldolization-hydrogenation of furfural-acetone mixtures

The performance of different bi-functional Pd catalysts (supported on Mg-Zr, Mg-Al and Ca-Zr mixed oxides) for the aqueous-phase aldol-condensation of acetone and furfural was studied in this work. Experiments were carried out in a batch slurry reactor at 323-393 K. Activity trends, as well as selectivity for the formation of the different adducts (C-8 and C-13), were correlated with the physico-chemical properties of the materials, mainly with the distribution of acid and basic sites. In general, it was observed that the catalyst with the lowest concentration of basic sites (Pd/Ca-Zr) presents the poorest performance. By contrast, the presence of medium-strength acid sites (as the observed in the case of one the Pd/Mg-Al catalyst) seems to enhance the catalytic activity of the material. Although selectivities trends were similar for the catalysts supported on Mg-Zr and Mg-Al catalysts, the ability of the materials for catalyzing the formation of the heaviest adducts depends mainly on the total concentration of basic sites. (C) 2010 Elsevier B. V. All rights reserved.