In-situ Encapsulation of Pt and Acid-Site Engineering in Hierarchical SAPO-11 for Enhanced Isomerization-cracking and Anti-Coking in Sustainable Aviation Fuel Production

Isomerization-cracking is a critical step in the preparation of sustainable aviation fuel (SAF). The practical application of conventional Pt/SAPO-11 catalysts is hampered by several deactivation mechanisms: metal sintering, pore blockage, and inefficient mass transfer of bulky molecules, all contributing to unsustainable performance over time. To overcome these challenges, this study introduces a novel Pt@SAPO-11-H catalyst, where sub-nanometric Pt clusters are encapsulated within a hierarchically porous SAPO-11 framework. The synthesis employs a ligand-assisted in situ encapsulation strategy with P123 as a mesoprogen. Beyond constructing hierarchical porosity, a critical secondary role of P123: the formation of amorphous AlPO 4 during crystallization, which selectively covers strong acid sites on SAPO-11. This acid-site engineering effectively suppresses excessive cracking, a key factor for maximizing SAF yield. Comprehensive characterizations confirmed the confinement of Pt clusters, the hierarchical pore structure, and the moderated acidity. Catalytic evaluation using octadecane as a model feedstock, achieving a 66.4% SAF yield with a 4.12 i/n ratio. The SAF yields of cottonseed oil, castor oil, palm oil, and tiger nut oil reached 82%, 70.2%, 79%, and 80% respectively. These results highlight the dual benefits of hierarchical porosity for enhanced diffusion and metal encapsulation for precise active site localization, offering a promising solution for scalable SAF production. A Pt@SAPO-11-H catalyst with encapsulated sub-nanometric Pt clusters and a hierarchically porous structure was designed. The acid sites were engineered using P123 to form amorphous AlPO 4 , enabling enhanced isomerization-cracking efficiency and selectivity for sustainable aviation fuel production. • A hierarchical Pt@SAPO-11-H catalyst was synthesized via in-situ encapsulation. • P123 creates mesopores and in-situ amorphous AlPO 4 to moderate acidity. • A high SAF yield of 66.43% with i/n=4.12 was achieved from octadecane. • Superior stability over 100 h with anti-coking due to confined Pt clusters. • Versatile performance with real oils, boosting SAF yield to 82.00%.