Regulate the mesopores and acidic structure of Pt/USY zeolite catalyst for improved performance in the hydroisomerization of phenanthrene to alkyl-adamantane

Abstract

Adamantane-based high energy density fuels (HEDFs) play a key role in military and aerospace applications due to their high volumetric calorific value and high density. In the preparation of adamantane-based HEDFs by hydroisomerization of polycyclic aromatic hydrocarbons (PAHs) in coal tar, there is competition between cracking and ring-opening reactions. Therefore, USY zeolites were etched with NaOH solution to expand the mesoporous and regulate the acidity, inhibit the cracking reaction, and promote the ring-shift isomerization of perhydrophenanthrene (PHP) to alkyl-adamantane (AlA), increasing the yield of AlA from 19% to 32%. There are two processes in the conversion of PAHs to AlA, hydrogenation and ring-shift isomerization. Phenanthrene was first hydrogenated to PHP, then isomerized to alkyl-adamantane, the product distribution of alkyl-adamantanes with different side chains was discovered, part of the C14 alkyl-adamantanes cracked, and the hydroisomerization reaction of PHP occurred only on the outer surface or pore mouth of USY zeolite. It provides a new perspective for the hydroconversion of PAHs to HEDFs.