Hydroisomerization Principles of Acenaphthene to Alkyladamantanes over Modified USY-Supported Pt Catalysts

Alkyladamantanes (AAs) are the ideal candidates for high energy density fuels for aviation propulsion due to their high density, high calorific values, and good low-temperature performance. However, the reaction process of AAs through the hydroisomerization of related polycyclic aromatic hydrocarbons (PAHs) remained unclear. This study focuses on investigating the hydroisomerization process of acenaphthene as a representative PAH using Pt/USY catalysts. To enhance the highest yield of the C12 AAs, USY zeolites were demetallized to enhance the diffusion and adjust the acidity. Additionally, the isomerization process of perhydroacenaphthene (PHA) was studied to examine the impact of different conformations of fully hydrogenated species. It was observed that the tiled trans-trans-trans conformation was more easily isomerized to AAs, likely catalyzed by multiple active sites. Based on the reaction network of anthracene, phenanthrene, and fluorene, the ability to form the perhydrophenalene type tricyclic structure was a necessary condition for the hydroisomerization of PAHs to AAs.