Reaction Mechanism of Naphthalene and α-Tetradecene Alkylation over H-FAU Zeolite Revealed by In Situ DRIFTS

This study aims to elucidate the reaction mechanism of naphthalene alkylation with long-chain α-tetradecene (α-C14H28) over H-FAU zeolite, a reaction critical for producing high-value alkylated aromatics in industrial catalysis. By combining in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) with kinetic and thermodynamic analysis, this study quantitatively tracks the evolution of four key carbocation intermediates formed on distinct Brønsted acid sites and identifies the Wheland-intermediate-forming step as rate-determining. For the first time, adsorption and diffusion analysis, reaction kinetics, and comprehensive catalyst characterization (XRD, NH3-TPD, pyridine-IR) are integrated to establish a complete mechanistic pathway. The results reveal how pore confinement and acid-site distribution govern intermediate evolution and overall activity, thereby offering a validated model for the rational design of selective and stable zeolite catalysts for continuous alkylation processes.