Tuning the mesopore-acid-metal balance in Pd/HY for efficient deep hydrogenation saturation of naphthalene

Hydrogenation of polycyclic aromatic hydrocarbons to saturate all rings is of great importance for hydrogen storage and fuel production, which is extremely hard due to the hardly broken π bond. In this work, various bifunctional catalysts of HY zeolite supported Pd (Pd/HY) are prepared by a facile impregnation method for hydrogenation saturation of naphthalene. The system of Pd/HY is finely tuned by changing the SiO2/Al2O3 ratio and mesopore volume of HY. The influences of active metal, acid sites and mesopores on the catalytic performance are revealed. A factor termed mesopore-acid-metal factor (X) is defined to comprehensively and quantitatively describe the states of mesopores, acid sites, and Pd NPs in the Pd/HY catalyst. In our catalytic system, X correlates the yield of decalin well with a R2 value of 96.03%. The quantitative structure-activity relationship of the Pd/HY system has been determined. By balancing the mesopores, acid sites and Pd state, high decalin yield and good stability have been achieved. In addition, the kinetic behaviors of naphthalene hydrogenation on the optimal catalyst are preliminarily investigated and the apparent activation energy for the formation of tetralin is calculated to be 61.64 kJ/mol.