Self-Bound Hierarchical Beta Zeolite Catalysts: Engineering Intracrystalline Mesopores for High-Efficiency Tetralin Hydrocracking

Abstract

Beta zeolite is widely used for the deep conversion of heavy oils (e.g., hydrocracking) owing to its strong acidity and suitable pore architecture; however, its purely microporous channels impose severe diffusion limitations for bulky molecules, restricting industrial performance. Herein, a predominantly crystalline shaped Beta zeolite catalyst with a tunable hierarchical pore network is developed by coupling TEAOH-induced secondary crystallization with a surfactant-assisted soft-templating strategy. This synergistic approach enables in situ binder-to-zeolite transformation while generating intracrystalline mesopores, yielding shaped bodies with high mechanical strength, tunable acidity, and interconnected micro-mesoporous pathways. A dual-template strategy is further developed, enabling fine-tuning of the mesoporosity. The superiority of pore engineering of shaped zeolite is further demonstrated in tetralin hydrocracking as a model reaction. The optimized 70BSi-0.6T-C catalyst achieves significantly enhanced performance, with a tetralin conversion of 94.9% and a high BTX yield of 28.5% at 380 °C and a high weight hourly space velocity of 8.0 h–1, markedly outperforming the untreated counterpart. The improved catalytic behavior is attributed to the synergistic effects of binder-to-zeolite transformation, restoration of Brønsted acidity, and enhanced mass transport enabled by intracrystalline mesopores. This work provides a general and scalable strategy for constructing industrially relevant hierarchical zeolite catalysts, offering improved activity and selectivity for the hydroconversion of bulky molecules.