Optimized Fabrication of Ni–Mo/USY@SBA-15 Core–Shell Catalysts via Acid-Tailored Synthesis for Enhanced Naphthalene Hydrocracking

Encapsulating the USY zeolite within a mesoporous SBA-15 shell is a promising strategy to construct hierarchical catalysts with regulated acidity. However, the acidic conditions required for SBA-15 synthesis pose a stability challenge to the acid-sensitive USY core. In this work, we first systematically investigated the physicochemical evolution of USY under simulated SBA-15 synthesis conditions by varying the acid concentration, temperature, and treatment time. Through XRD, N2 physisorption, NH3-TPD, and Py-FTIR analysis, the optimal conditions for USY to retain its framework integrity and Brønsted acidity were determined to be ≤1.0 M HCl and treatment time ≤24 h. This acid-tailored optimization is essential for the subsequent fabrication of the core–shell structure. Guided by these findings, the Ni–Mo/USY@SBA-15 core–shell catalyst is successfully prepared and evaluated in naphthalene hydrocracking, achieving 97.8% conversion and 51.6% BTX selectivity, outperforming conventional Ni–Mo/USY (92.6% conversion and 26.0% BTX selectivity). XPS analysis provides direct evidence of the spatially regulated metal-acid distribution and enhanced electron density on active sites. The performance enhancement is attributed to the hierarchical pore structure and the spatially regulated metal-acid distribution, which together enhance mass transfer, optimize acid site accessibility, and suppress overcracking. This study provides an acid-tolerance-guided synthesis strategy for designing high-performance core–shell zeolite catalysts.