Efficient and stable Pd catalyst confined in microporous carbon shells for phenol hydrogenation

•Pd@CS nanosphere reactor with well-define core-shell structures were successfully synthesized through hydrothermal methods.•The FT-IR results in the mechanism exploration revealed the synthesis pathway of Pd@CS nanospheres.•The Pd@CS-3.5 h had the lowest activation energy (81.16 kJ/mol).•The optimal adsorption site and reaction pathway for the hydrogenation of phenol were investigated using DFT. In this article, Pd@CS nanosphere reactor with well-define core–shell structures were successfully synthesized using glucose and potassium tetrachloropalladium as C and Pd sources, respectively, through one-step hydrothermal methods. Obtained Pd@CS nanospheres exhibit excellent activity and stability for hydrogenation reaction of phenol to cyclohexanone. Under the conditions of 150 °C and 2 MPa H2, phenol was converted to cyclohexanone with a conversion of 99.9 % and a selectivity of 98.6 % within 3 h. In addition, Pd@CS has good stability and reusability, and the activity loss is not obvious, after 5 cycles, the selectivity is still above 95.0 %. The fourier transform infrared spectroscopy (FT-IR) results in the mechanism exploration revealed the synthesis pathway of Pd@CS nanospheres. Finally, based on the density functional theory (DFT) results of the adsorption configuration of phenol on the surface of Pd clusters, the optimum adsorption position and the first hydrogenation site of phenol were investigated, and the reaction path of hydrogenation of phenol to cyclohexanone was summarized.