Toward <i>n</i>-Alkane Hydroisomerization Reactions: High-Performance Pt–Al<sub>2</sub>O<sub>3</sub>/SAPO-11 Single-Atom Catalysts with Nanoscale Separated Metal-Acid Centers and Ultralow Platinum Content
Rui Yu, Yangchun Tan, Heliang Yao, Yanhui Xu, Jian Huang, Bin Zhao, Yanyan Du, Zile Hua, Jiusheng Li, Jianlin Shi
Abstract
Long-chain n-alkane hydroisomerization reaction plays a vital role in petrochemical and coal chemical industries, which could produce high-quality hydrocarbon fuels and lubricant base oils for modern transportation and mechanical drive. However, minimizing precious metal usage while maintaining the catalyst performance remains a great challenge. Herein, a novel bifunctional catalyst toward n-alkane hydroisomerization reactions, Pt–Al2O3/SAPO-11 (Pt-A/S11) featuring nanoscale separated metal-acid active centers has been synthesized via a simple two-step procedure. In detail, Pt species was first loaded on the nanometer-sized alumina matrices through an incipient wetness impregnation method and then mixed with SAPO-11 molecular sieve to form the composite catalyst. Importantly, 0.015Pt-A/S11 catalyst with the ever-reported lowest Pt loading amount of 0.015 wt % exhibits an extraordinarily high isomer yield of 85.8% compared to previous published results and the traditional Pt-SAPO-11/Al2O3 (Pt–S11/A) catalyst accompanying with the direct contact between metal and acid sites (65.6%). It has been confirmed that the Pt species in 0.015Pt-A/S11 samples exist in single-atom form, leading to an excellent hydroisomerization performance. The possible reaction processes have been discussed to elucidate the exemplary catalytic performance of the synthesized Pt-A/S11 catalysts with nanoscale intimacy of metal-acid sites.