Effect of Cavity Microenvironment in Cobalt-Encapsulated Hollow Carbon Spheres on Selective Phenol Hydrogenation to Cyclohexanol

Cyclohexanol is not only an important intermediate in the chemical industry, but also a key component in the production of green energy. Catalyzed hydrogenation of phenol to produce cyclohexanol is a green and efficient method. This work employed the soft template method to prepare hollow carbon-coated cobalt nanoreactors with different physical microenvironments by varying the amount of HMT (Hexamethylenetetramine) added. The results show that the cavity size and curvature of the hollow carbon spheres reactor have a significant effect on the reaction. Comprehensive characterizations (TEM, XRD, XPS, H2-TPR, etc.) and experimental data indicate that the optimized Co@HCS-0.25-500 promotes the adsorption and hydrogenation of phenol through the synergistic effects of curvature-induced electronic metal-support interactions and enhanced reactant enrichment in the larger cavities. The optimized Co@HCS-0.25-500 achieved a phenol conversion of 56.4% and >99% cyclohexanol selectivity under conditions of 140 °C, 1 MPa H2, 1 h. Co@HCS-0.25-500 exhibited excellent stability in six consecutive cycles and demonstrated good general applicability in the hydrogenation of biomass-derived phenolic compounds.