Hydrogenation kinetic of alkenes and aromatics over NiMo hydrotreatment catalysts

Hydrotreatment is a critical process in the petrochemical industry to produce gasoline or diesel. Proper kinetic models and accurate kinetic parameters of hydrotreatment reactions are important for the industrial reactor design and scale-up research. In this work, hydrogenation kinetics of alkene and aromatic model compounds were studied thoroughly to provide deep understanding on alkene and aromatic hydrogenation behaviors in gasoline and diesel hydrotreating. Commercial NiMo hydrotreatment catalysts were used to obtain experimental data of hydrogenation reactions. Cyclohexene, 1-octene, naphthalene and phenanthrene were used as model compounds of alkenes and aromatics. Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic models for hydrotreatment reactions were established. In addition, phase equilibrium calculations were combined with kinetic study, and it is discovered that using calculated liquid phase compositions as kinetic model input could greatly enhance the accuracy of kinetic models and the quality of kinetic parameters, leading to higher accordance with experimental results. Using kinetic models and phase equilibrium analysis, the effect of reaction conditions (temperature, pressure, and H₂/oil ratio) on reaction rates were also predicted and clarified. The importance of phase equilibrium in kinetic analysis for hydrotreating reactions was demonstrated in this study, which provides an effective approach for future hydrotreatment reactor design and catalyst optimization.