Engineering Hierarchical NiMo/USY Catalysts for Selective Hydrocracking of Naphthalene to BTX

The selective hydrocracking of polycyclic aromatic hydrocarbons to BTX requires precise control over catalyst porosity and metal–acid balance. Hierarchical porosity, integrating microporous and mesoporous networks, is pivotal for enhancing mass transport and regulating reaction pathways. USY zeolites were engineered to create distinct hierarchical architectures via HCl, urea, and NaOH–surfactant treatments. HCl treatment constructed a gradient pore acidity system, urea treatment enhanced acidity while preserving microporosity, and NaOH–surfactant fabricated ordered mesopores with reduced acidity. The catalyst with the HCl-engineered gradient pore (NiMo/YH-1) achieved a 91% BTX yield at 425 °C in naphthalene hydrocracking, outperforming others. This performance is attributed to its gradient structure that enforces an optimal “hydrogenation-then-cracking” pathway, highlighting the critical role of tailored hierarchical porosity.