Kinetic Study on the Reaction and Deactivation Behavior of Hydrodearomatization Catalysts During Initial Use.

Abstract

Amidst increasing environmental regulations, reducing the aromatic content in diesel oil has become a challenge in the refining industry. This study investigated the kinetics of hydrodearomatization and catalyst deactivation on a CoMo/Al₂O₃ catalyst using a fixed-bed reactor in the lab. Experiments were conducted with blended feedstocks of straight-run diesel and catalytic cracking diesel. A lumped kinetic model considering the influence of competitive adsorption was built up, and the model parameters were estimated using optimization methods, achieving satisfactory results. Research shows that aromatic saturation is reversible, with optimal conditions favoring saturation, including elevated pressure, reduced liquid hourly space velocity, and controlled temperature (360 °C). Based on the established reaction kinetic model, a catalyst deactivation kinetic model was proposed, correlating catalyst activity with feedstock properties and process severity, revealing the activity change of the catalyst in the early stage of use: increased temperature and decreased liquid hourly space velocity accelerate the deactivation of catalysts in all hydrodearomatization reactions, while feedstock and reaction pressure show different trending effects on catalyst deactivation for different types of reactions.