Highly Selective Hydrogenation of Isophorone to 3,3,5-Trimethylcyclohexanone Using Ru–Ni@RGO: Kinetics, Mechanism, and Catalyst Reusability

Abstract This study investigated the selective hydrogenation of the C═C bond in α,β-unsaturated ketone isophorone to produce the value-added intermediate 3,3,5-trimethylcyclohexanone (TMCH). A bimetallic Ru–Ni catalyst supported on reduced graphene oxide (RGO) was developed and optimized, with 15 wt % (Ru/Ni = 1:3) called Ru–Ni@RGO exhibiting superior performance. Under mild conditions (80 °C, 15 bar H2 pressure, 800 rpm in the lab reactor, 3.5 h), the catalyst achieved 99.4% conversion with 100% selectivity toward the desired product. Comprehensive physicochemical characterization revealed strong metal–support interaction (SMSI) and synergistic effects between Ru and Ni, contributing to enhanced activity and selectivity. A possible reaction mechanism was proposed, and kinetic model developed. The model was validated against experimental data. The catalyst demonstrated excellent stability, with complete recovery and reuse over multiple cycles without significant loss of performance. The process offers a sustainable and efficient route for the selective hydrogenation of isophorone, with potential industrial relevance.