Trickle-bed reactor models for systems with a volatile liquid phase

A significant number of gas-liquid-solid catalyzed reactions in the petroleum processing and chemical industries are carried out in trickle-bed reactors under conditions where substantial volatilization of the liquid phase can occur. A review of the limited literature on experiments and models for trickle-bed reactor systems with volatile liquids is presented first. A rigorous model for the solution of the reactor and pellet scale flow-reaction-transport phenomena based on multicomponent diffusion theory is proposed. To overcome the assumptions in earlier models, the Stefan-Maxwell formulation is used to model interphase and intra-catalyst transport. The model predictions are compared with the experimental data of Hanika et al. (1975, Chem. Engng Commun., 2, 19-25; 1976, Chem. Engng J., 12, 193-197) on cyclohexene hydrogenation and also with the predictions of a simplified model (Kheshgi et al., 1992, Chem. Engng Sci., 47, 1771-1777). Rigorous reactor and pellet-scale simulations carried out for both the liquid-phase and gas-phase reaction, as well as for intra-reactor wet-dry transition (hysteresis and rate multiplicity), are presented and discussed. Comparisons between various models and pitfalls associated with introducing simplifying assumptions to predict complex behavior of highly non-ideal three phase systems are also presented. (C) 1999 Elsevier Science Ltd. All rights reserved.