Cascade Upgrading of Furfural to Alkyl Levulinate over Ni Exchanged Supported 12-Tungstophosphoric Acid: Concerted Effects of Lewis/Brønsted Acidic Sites

Abstract

The new insights toward the cascade synthesis of isopropyl levulinate (i-PL), an important biofuel additive and precursor to the highly valued γ-valerolactone (GVL), from bioderived furfural (FA) via Meerwein−Ponndorf−Verley (MPV) reduction followed by alcoholysis were studied. For that, a sustainable catalyst nickel exchanged 12-tungstophosphoric acid anchored to zeolite HY was synthesized and characterized by different techniques such as FTIR, UV−vis−NIR, TGA, BET, XRD, 31 P NMR, HRTEM, EDX, and XPS. The total acidity as well as types of acidity was studied by NH 3 -TPD and pyridine FTIR. The catalyst exhibited its exceptional performance to attain 72% yield of i-PL which successfully implied the strategy of "say no to external H-source" leading to a remarkable turnover number (1385). The sustainable features of the catalyst were boosted by its regeneration and reuse. The comparison study highlighted the superiority of the catalyst in terms of employing a non-noble metal as well as the highest yield of the desired product. The reaction pathway was also proposed on the basis of control experiments.