Chemoselective hydrogenation of furfural to furfuryl alcohol on ZrO2 systems synthesized through the microemulsion method

Different solids consisting in hydrous zirconia were synthesized by the water in oil microemulsion technique (ME series). For comparative purposes, diverse solids were also obtained by the conventional sol-gel method (Pseries). The solids were tested for liquid-phase selective hydrogenation of furfural to furfuryl alcohol, using propan-2-ol as the hydrogen donor (Meerwein-Ponndorf-Verley process). The best results corresponded to catalysts calcined at 200 degrees C which consisted in amorphous solids with surface areas of ca 200 m(2)/g. The presence of some surfactant remaining from the synthetic process in solids obtained through the microemulsion technique favored selectivity to furfuryl alcohol with values >= 98%. Results were explained by the steric hindrance of furfural by the surfactant molecules in micelles thus favoring the interaction of the substrate with hydroxyl groups in hydrous zirconia through the C=O group. Application of microwave irradiation accelerated the reaction (15-30 times) as compared to conventional heating.