Synergistic Effect of Iridium and Weak Acid Sites on SAPO-34 for the Deep Hydrogenation of Anthracene

Abstract

Polycyclic aromatic hydrocarbons (PAHs) in coal direct liquefaction heavy oil exhibit a complex aromatic structure and poor combustion performance. Hydrogenation of PAHs increases the hydrogen content and energy density, making them promising candidates for aviation fuel and enabling the efficient and clean utilization of coal liquefaction heavy oil. However, achieving selective deep hydrogenation of PAHs without ring opening critically relies on the optimal density and accessibility of acid sites to establish a robust metal–acid synergy. In this work, a controlled HCl etching strategy was employed to re-engineer the surface of SAPO-34, which loaded Ir nanoparticles to establish a synergistic effect of Ir and weak acidity. N2 adsorption–desorption isotherms and pyridine-infrared spectroscopy analyses revealed that the optimal HCl treatment effectively removed pore-blocking impurities, thereby significantly maximizing the exposure of accessible weak acid sites. This tailored structural modulation established a highly efficient “accessible weak acid sites–Ir nanoparticles” synergistic system, which fundamentally favored the deep hydrogenation reaction pathway. Compared to commercial SAPO-34, Ir nanoparticles supported on optimal HCl-treated SAPO-34 enhanced the selectivity of octahydroanthracene from 3.31 to 42.78% while simultaneously maintaining high hydrogenation activity.