Factors Controlling Highly Efficient Ultralow-Content Ru Catalyst for Selective Hydrogenation of Dimethyl Terephthalate to Dimethyl 1,4-Cyclohexanedicarboxylate

The catalytic hydrogenation of dimethyl terephthalate (DMT) to dimethyl 1,4-cyclohexanedicarboxylate (DMCD) is a widely used process on a scale of over 250 kilotons. However, conventional catalysts require expensive noble metals with high loadings and harsh operating conditions, resulting in high costs and safety concerns. In this study, we have evaluated the metal loadings and supports in a rational manner and present a simple yet highly efficient low-content ruthenium (Ru) catalyst for the selective hydrogenation of DMT to DMCD. This catalyst achieves up to 100% conversion and 96% selectivity for DMCD formation with 6330 turnover numbers (TONs) and 528 h –1 turnover frequencies (TOF) with up to 21044 TONs in catalyst recycling experiments. Comprehensive characterization and structure–activity analysis reveals that the TiO 2 -γ-Al 2 O 3 composite support bearing with rich mesopores, surface areas, oxygen vacancies and balanced acid–base properties, stabilizes nanocrystalline Ru particles with abundant Ru 0 species, thus facilitating effective substrate adsorption, activation and hydrogenation.