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

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, 31P NMR, HRTEM, EDX, and XPS. The total acidity as well as types of acidity was studied by NH3-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.