Hydrogenation of Bisphenol A-Type Epoxy Resin (BE186) over Vulcan XC72-Supported Rh and Rh–Pt Catalysts in Ethyl Acetate-Containing Water

This study demonstrates the hydrogenation of a bisphenol A-type epoxy resin (BE186) through solvent selection, development of a catalyst for aromatic ring hydrogenation, and control of epoxy loss. A functional greener solvent, water in ethyl acetate, was proposed based on solvatochromic parameters, high α and low β. RhOx present in Vulcan XC72-supported monometallic Rh and bimetallic Rh–Pt catalysts prepared by the polyol method acted as a promoter for hydrogenation. The hydrogenation pathway to control epoxy loss was proposed through changes of the reactant to the catalyst ratio and temperature. Though Rh–Pt catalysts were superior to Rh for aromatic ring hydrogenation, they led to higher epoxy loss owing to excessive C–O bond cleavage. Using Rh5/Vulcan XC72-polyol, 3 wt % water in ethyl acetate, and a reactant to catalyst ratio of 100:1, complete hydrogenation of BE186 with 3.4% epoxy loss was achieved at a H2 pressure of 1000 psi and 60 °C for 3.5 h.