Selective Hydrogenation of Benzene in the Presence of Aromatic Hydrocarbons: Mechanisms, Catalysts, and Modern Approaches

Abstract

This review article systematizes current knowledge on the catalytic hydrogenation of benzene as a key process in petrochemistry, environmental protection, and hydrogen energy technologies. The fundamental mechanisms of benzene ring activation and molecular hydrogen dissociation on transition metal surfaces are discussed, with particular emphasis on the disruption of aromatic stability as the rate-limiting step of the reaction. Special attention is given to the challenge of achieving selective benzene hydrogenation in the presence of other aromatic compounds, a situation typical of reformate and pyrolysis gasoline fractions. The influence of the active metal type (Ni, Pd, Pt, Ru), catalyst supports (oxide, zeolitic, carbon-based, and natural materials), and reaction parameters (phase, temperature, and hydrogen pressure) on catalytic activity, selectivity, and stability is systematically analyzed. Competitive adsorption among aromatic compounds, the role of electronic and steric effects of substituents, and mass-transfer limitations in liquid-phase systems are also examined. Results obtained for both industrial and emerging catalytic systems are summarized, including catalysts for the deep and partial hydrogenation of benzene, as well as their potential applications in liquid organic hydrogen carrier (LOHC) technologies. Achieving high selectivity therefore requires comprehensive optimization of catalyst composition, support structure, and process conditions, which defines the main directions for future research.