Selective hydrogenation of dimethyl terephthalate over a potassium-modified Ni/SiO₂ catalyst

Selective hydrogenation of dimethyl terephthalate (DMT) is an ideal way to prepare 1,4-cyclohexane dicarboxylate (DMCD), an important intermediate and monomer. Even though noble metal-based catalysts (e.g., Ru, Pd) have been developed for selective hydrogenation of DMT, the use of non-precious Ni catalysts to achieve high activity and selectivity is still challenging. In this study, we present that only 0.5 wt% of KF by post-impregnated doping can significantly improve the performance of Ni/SiO₂ catalysts (83% vs. 96% selectivity; 41% vs. 95% conversion). The selectivity of DMCD can be up to 97%, which is the highest reported over Ni catalysts. The boosting effect of KF modification might be due to higher amounts of Ni(0) species and lower amounts of moderate acidic sites, which are beneficial for selective hydrogenation of phenyl rings over hydrogenolysis of ester groups.