Zr Oxo Cluster for Cascade Conversion of Furfural to Alkyl Levulinates

Abstract

A novel dodecanuclear Zr oxo cluster [Zr6O4(OH)4 (HSCH2CH2COO)12]2 (ZrO‐SH‐10) has been constructed under the room temperature, followed by oxidation of the sulfhydryl group with H2O2 to achieve a bifunctional catalyst with Lewis acid and Brönsted acid sites. The characterization of catalysts indicated that {Zr6O4} cluster core can be stabilized with a shell of carboxylate ligands, and the resulting ZrO‐SO3H was formed as a discrete molecular catalyst, exhibiting superior activity and recyclability for the cascade conversion of furfural to alkyl levulinate by the integration of transfer hydrogenation and alcoholysis in n‐butanol. The yield of n‐butyl levulinate can achieve as high as 91 % under the optimum conditions. Meanwhile, no leaching of the active species was found, which confirmed the structure of the Zr oxo cluster was air and moisture‐stable. On the basis of the studies on the reaction kinetics and isotope tracking, the reaction mechanism was proposed accordingly.

High-Efficiency Production of Biomass-Derived 5-Alkoxymethylfurfurals over a Lewis–Brønsted Bifunctional Carbonaceous Acid Catalyst

“…As for GHTC, the characteristic peaks at around 1021 and 1704 cm –1 were assigned to the vibrations of C–O bond and CO bond in the −COOH groups, – respectively, and the characteristic peak at around 3432 cm –1 was ascribed to the vibration of O–H bond in the −COOH groups and Ph–OH groups. – Moreover, the characteristic peak at around 1624 cm –1 was due to the vibration of CC bond, and the characteristic peaks at around 798, 1363, and 2926 cm –1 were attributed to the vibration of C–H bond in aromatic rings. – These observations demonstrated that GHTC contained abundant −COOH and Ph–OH groups, which were immobilized on the aromatic carbons in the carbonization process of glucose. Compared with GHTC, the characteristic peak intensities of −COOH groups and Ph–OH groups evidently weaken in Zr-GHTC (Figure S1), and at the same time, two characteristic peaks of the Zr–O bond at around 462 and 650 cm –1 were found in Zr-GHTC, – which indicated that Zr was triumphantly coordinated with O in the – COOH groups and Ph–OH groups of GHTC. When Zr-GHTC was sulfonated by CSA, the characteristic peaks of C–S bond and OSO bond at around 534 and 1227 cm –1 were observed in Zr/GHTC–SO 3 H, – respectively, which suggested that −SO 3 H groups were successfully incorporated into Zr/GHTC–SO 3 H in the sulfonation process of Zr-GHTC.…”

Ionic Liquid-Regulated Titanium Oxo Clusters Catalyze Selective Oxidation of Anilines to Azoxybenzenes

“…The experimental results were then fitted to these equations by the MATLAB program. , Then the obtained reaction rate constants were used to evaluate the apparent activation energy ( E a n , n = 1, 2, 3) by plotting ln k versus 1/ T through the Arrhenius equation (Figure ). Table summarizes the rate constants and activation energies of each reaction.…”