The role and performance of isolated zirconia sites on mesoporous silica for aldol condensation of furfural with acetone

Furfural is an important bio-based platform chemical in the production of valuable products such as biofuel intermediates and polymeric materials. In this work, isolated Zr on mesoporous silica catalysts at varied Zr loading were prepared and evaluated for aldol condensation of furfural with acetone to 4-(2-furyl)− 3-buten-2-one(FAc) and 1,5-bis-(2-furanyl)− 1,4-pentadien-3-one(F2Ac). A remarkable effect of the Zr loading on the catalyst performance is revealed. The catalysts are characterized by XRD, BET, NH3-TPD, Py-FTIR, XPS, UV–visible, and TGA. The connectivity of Zr was characterized by XPS and UV–visible spectroscopy. For the 25 wt% Zr loading, Zr is present predominantly as isolated monomeric species on mesoporous SiO2. The types and densities of different acid sites of the catalysts are measured with Py-FTIR analysis. The results show that isolated Zr on mesoporous SiO2 enhanced Lewis acid site densities and exhibited superior catalytic activity for aldol condensation between furfural and acetone to produce FAc and F2Ac. [Display omitted] •Highly dispersed Zr on m-SiO2 catalyst exhibited high activityfor aldol condensation of furfural with acetone.•The rate of aldol condensation correlated with the Lewis acidic sitedensity of Zr doped on m-SiO2.•The catalyst was stable and no leaching of active sites in recycled uses.