Assessment and Modeling of Adsorption Selectivities in the Transport of Mixtures of Hydrocarbons in FCC Catalysts

ADOLFO M. AVILA; C.M. BIDABEHERE; U. SEDRAN

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

American Chemical Society

Lugar: Columbus, Ohio, USA; Año: 2007 vol. 46 p. 7927 - 7935

0888-5885

Adsorption experiments with up to 10 s contact time in a batch adsorber with a ternary mixture of hexane, decane and toluene at 250ºC and a binary mixture of hexane and 1-hexene at 160 ºC were used to assess equilibrium and apparent adsorption selectivities and diffusion selectivities in an equilibrium commercial FCC catalyst; and confirm the predictions of a zeolite diffusion ? adsorption model based on the Maxwell ? Stefan formulation in combination with an isotherm according to the ideal adsorbed solution theory IAST. Hexane was the reference hydrocarbon, and the decane and toluene apparent selectivities observed in the mixture were higher than those of the individual cases. The predictions of the apparent adsorption selectivities were close to the experimental values and higher than those for diluted conditions. The stronger adsorption of decane and the interactions between the various species within the zeolite particles contributed positively to decane overall transport in comparison to the other hydrocarbons in the mixture. Such interaction effects can be clearly visualized in the simulation of the transient adsorbate concentration profiles inside the zeolite particles. A similar behavior was observed in the case of the olefin in the hexane/hexene mixture.