Implementation of the Vapor-Liquid Equilibrium On the Kinetic Model for the Oligomerization of Olefins

The oligomerization of light C₂-C₄ olefins has emerged as one of the most studied processes for the sustainable production of different refinery cuts of interest as green fuels, such as gasoline, diesel, or aviation fuels. However, oligomerization is a complex process in which the presence of a gas and liquid phase (heavy oligomers) leads to unique phenomena in this reaction: an apparent initial deactivation of the catalyst due to the pore filling with retained oligomers and a steady state of catalyst constant activity. These features make it difficult to develop robust kinetic models to simulate the reactor and upscale the process. Herein, a lump kinetic model has been developed for the simulation of 1-butene oligomerization in a packed-bed reactor using a catalyst of the HZSM-5 zeolite embedded in a mesoporous γ-Al₂O₃ matrix. The computation methodology is based on a one-dimensional three-phase reactor model combined with vapor-liquid equilibrium calculations and a concentration-dependent deactivation equation. The compounds in the gas phase were considered reactive, while those in the liquid phase were assumed to be retained in the catalyst pores. The model suitably fitted the experimental data obtained at 40 bar, different temperatures (150-250 °C), and space-time values up to 5.7 g h mol_C ^-1. The proposed model reconciled some of the observations in literature for oligomerization, such as the effect of the retained liquid as deactivation kinetics distorted by pore diffusion resistance or the higher stability (high remanent activity) in the presence of the liquid flow.