Preparation of dimethyl 1,4-cyclohexanedicarboxylate by Ru/HZSM-5-catalyzed hydrogenation of dimethyl terephthalate

Abstract

BACKGROUND

Dimethyl 1,4-cyclohexanedicarboxylate (DMCD) has emerged as a critical feedstock in contemporary chemistry, attributed to its distinctive molecular composition and good environmental compatibility. This study explored the targeted hydrogenation of dimethyl terephthalate (DMT) to produce DMCD, with a focus on screening and optimizing various Ru-based catalysts. Of the catalysts evaluated, those supported on HZSM-5 and enriched with weak acid sites demonstrated superior catalytic performance. Additionally, the impact of various reaction conditions on DMT conversion and DMCD selectivity was thoroughly examined.

RESULTS

The Ru/HZSM-5 catalysts, synthesized via the impregnation technique, exhibited remarkable catalytic efficiency in the reduction of DMT. Ru on the HZSM-5 support primarily exists in the forms of Ru⁰ and Ru⁴⁺, with the Ru⁰ content identified as the critical factor governing the catalytic performance. Under the experimental parameters of 160 °C, 2.5 MPa H₂, and 2 h reaction time, the 3 wt.% Ru/HZSM-5 catalyst could achieve 100% DMT conversion and 99.5% DMCD selectivity. Furthermore, the catalyst maintained high activity after three cycles of use.

CONCLUSION

The Ru/HZSM-5 catalyst displays outstanding stability during the hydrogenation of DMT to DMCD. The exceptional performance is ascribed to the moderate Ru loading, the even distribution of Ru nanoparticles, and the synergistic effects between the high hydrogenation activity of Ru⁰ and the weak acidic sites of HZSM-5. This research offers a novel approach to designing effective and stable hydrogenation catalysts and establishes a crucial foundation for the sustainable synthesis of DMCD. © 2025 Society of Chemical Industry (SCI).