Research on the reaction mechanism and molecular stacking of acid catalyzed naphthalene to prepare mesophase pitches

Abstract

Mesophase pitches (MPs) act as crucial precursors for the production of high-performance carbon materials. The initial step in MP generation involves the formation of planar condensed polycyclic aromatic hydrocarbon (PAH) macromolecules. This study unveils the catalytic reaction mechanism leading to the production of planar condensed PAH macromolecules through DFT theoretical calculations. Our research delineates that the generation of planar condensed PAH macromolecules entails five key reactions: protonation reaction (PRO), intermolecular electrophilic addition reaction (IEEA), intramolecular electrophilic addition reaction (IAEA), dehydrogenation reaction (DEH), and deprotonation reaction (DEP). The reaction pathway demands substantial energy input and the presence of a strong acidic catalyst. Through molecular dynamics simulations, this study compares the stacking of product molecules with various structures, affirming the role of intramolecular electrophilic addition reaction and dehydrogenation reaction in enhancing molecular planarity and facilitating their orderly arrangement. Molecular interactions are elucidated to unveil the mechanism behind the formation of stacked graphite-like structures. The research findings not only offer a comprehensive explanation consistent with experimental observations but also mark a significant step in understanding the formation of MPs, elucidating the ideal product structure, formation pathway, and the factors influencing orderly molecular stacking. This study, for the first time, comprehensively unveils the reaction mechanism underpinning MP formation, shedding light on environmentally friendly catalyst development. It establishes crucial guidelines for MP preparation conditions and provides theoretical underpinnings for the production of enhanced-performance MPs.