Construction of Hierarchical Porous Carbon Support Pd Nanoparticle for Efficient Pyridine Hydrogenation Catalysis

Pd-based catalysts are increasingly being used in pyridine hydrogenation. Suitable catalyst supports are crucial for catalytic activity. Herein, three Pd-based catalysts loaded on microporous carbon (AC), mesoporous carbon (MC), and micromesoporous carbon (MAC) were tested for pyridine hydrogenation. The influence of catalyst supports, their porosity characteristics, and reaction conditions on the catalytic performance was investigated. The results show that Pd/MAC catalyst exhibits optimal catalytic activity, which can achieve 99% conversion of pyridine and 99% yield of piperidine under the conditions of balloon pressure and room temperature. Specifically, Pd/MAC has excellent catalytic activity even after 5 cycles and shows high compatibility with various N-heterocycles with a high yield. The excellent catalytic performance is attributed to its multistage pore structure and a high specific surface area, which provide more defects for loading of active sites and accelerate the mass transfer rate, and the uniformly dispersed ultrafine active palladium nanoparticles can also greatly enhance the catalytic activity. This work provides a feasible research idea for the preparation of hydrogenation catalysts for pyridine analogues.