High-Performance Ni–Al Catalysts for Hydrogenation of C5/C9 Petroleum Resins: Effects of Catalyst Composition on Dispersibility, Stability, and Reaction Kinetics

A highly dispersed and stable nickel–aluminum (Ni–Al) bimetallic catalyst was synthesized via a coprecipitation method combined with spray granulation technology. The catalyst composition and preparation parameters were investigated systematically. When the nickel and aluminum contents in the catalyst reached 64.4 and 5.6 wt %, respectively, the catalyst exhibited significantly enhanced structural stability while maintaining high hydrogenation activity. The structure–activity relationship was elucidated by multiple characterization techniques. XRD and SEM characterization revealed that the interaction between aluminum and nickel formed a nickel–aluminum orthorhombic crystal system, which enhanced the structural stability and dispersion of the catalyst significantly. The degree of hydrogenation of the C5/C9 petroleum resins was determined by infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectroscopy. The hydrogenation process was optimized using response surface methodology, and kinetic analysis was conducted under conditions that eliminated diffusion limitations. Through the aforementioned studies, the activation energies (Ea) for the hydrogenation reactions of C5 and C9 hydrocarbons were determined to be 48.978 and 49.948 kJ/mol, respectively. Attempts were made to elucidate the hydrogenation mechanism of the catalyst and the reasons for catalyst deactivation. This work provides a viable strategy for designing highly efficient nonprecious metal catalysts, which can effectively enhance the quality of petroleum resins.