Tungsten-Modulated Ru/ZrO₂ Catalysts Promote Selective Hydrogenation of Phthalide to Hexahydrophthalide: Synergistic Effects of Metal–Support Interaction and Acidic Characteristics

The development of chemically recyclable polyester derived from lactone ring-opening polymerization monomer hexahydrophthalide offers a promising solution to the plastic pollution issue. The selective hydrogenation of phthalide to hexahydrophthalide is a green atom-economy route; however, the selective hydrogenation of the benzene ring in phthalide containing different functional groups is a significant challenge. In this work, a series of W-modified Ru/ZrO2 catalysts were prepared via impregnation followed by liquid-phase reduction, and the effect of tungsten loading on catalytic performance was systematically evaluated for the hydrogenation of phthalide. Under 4 MPa H2 and 180 °C, the conversion of phthalide and the selectivity of hexahydrophthalide reach 98.6% and 80.4% on the Ru/15WZr catalysts, respectively. Compared to the Ru/ZrO2, it has a relatively low activation energy (51.49 kJ/mol) and excellent catalytic stability, with 110 h of catalytic performance remaining basically unchanged. The introduction of W species enhances the interaction between Ru and the support, generating an electron-deficient Ruδ+ structure and abundant acidic sites. This leads to the directional activation and hydrogenation of the aromatic ring of phthalide, thereby improving the selectivity of hexahydrophthalide. This work not only provides fundamental insights into the design of efficient hydrogenation catalysts but also establishes a versatile strategy for converting phthalide to recyclable lactones through precise control of the active sites.