Unraveling the effects of pore structure on the performance of Ru/SiO2 catalysts for the selective hydrogenation of dimethyl terephthalate to dimethyl 1,4-cyclohexanedicarboxylate

Ru/Fumed SiO 2 achieves 100% DMT conversion and 100% DMCD selectivity. • Macropores of Fumed SiO 2 lower diffusion barriers and enhance active site utilization. • Strong Ru-O-Si interaction promotes Ru dispersion and ensures 5-cycle reusability. • Low apparent activation energy enables high-efficiency aromatic ring hydrogenation. The growing accumulation of waste polyethylene terephthalate (PET) causes severe resource depletion and environmental pollution, making its high-value chemical recycling essential for sustainable development. PET methanolysis affords dimethyl terephthalate (DMT), and its selective hydrogenation to dimethyl 1,4-cyclohexanedicarboxylate (DMCD) connects waste PET valorization with high-performance polyester synthesis. Herein, a series of Ru-based catalysts supported on microporous-dominated S-1, ordered mesoporous MCM-41 and SBA-15, and Fumed SiO 2 with the open interparticle macro-mesoporous were prepared by the incipient wetness impregnation, and the role of support pore structure in DMT hydrogenation to DMCD was systematically examined. The results show that the open interparticle macro-mesoporous framework of Fumed SiO 2 alleviates diffusion constraints and improves the accessibility of Ru active sites. This structure enables uniform Ru dispersion, giving Ru/Fumed SiO 2 the smallest average Ru particle size (6.0 nm). Surface Si-OH groups anchor Ru species through Ru-O-Si interfacial structures, which strengthens metal-support interactions and promotes H 2 activation and active-site utilization. Under 180 °C, 3.0 MPa H 2 , and 3 h, Ru/Fumed SiO 2 delivers 100% DMT conversion and 100% DMCD selectivity. It also shows the lowest apparent activation energy (39.0 kJ·mol −1 ), stable performance over five cycles, and over 93% conversion and selectivity for representative substituted aromatic compounds. These findings demonstrate that an open interparticle macro-mesoporous framework could improve molecular accessibility, mitigate mass-transfer limitations, and enhance hydrogenation efficiency. Download: Download high-res image (185KB) Download: Download full-size image