Adsorption of propane and propylene in zeolite 4A honeycomb monolith

Abstract

One of the developments in separation technologies by adsorption is the use of new shaped structured materials offering some attractive properties rather than pellet or extrudates behavior. Monolithic adsorbents have actually been studied in a wide range of applications. It is the purpose of this work to report the behavior of a square honeycomb monolith containing zeolite 4A crystals inserted by extrusion. Adsorption equilibrium of pure gases was measured at 423 and 473 K in a Rubotherm microbalance, and data were in agreement with commercial extrudates data. Diffusivity coefficients of propylene were determined by uptake curves at low pressures; D c ( 423 ) = 0.56 × 10 - 17 m 2 / s and D c ( 473 ) = 2.00 × 10 - 17 m 2 / s . These values are three orders of magnitude smaller than that of previous data measured in commercial extrudates due to partial blocking of the micropores of the zeolite with one of the materials used in the monolith preparation. A complete mathematical 3D-distributed parameter model for fixed-bed adsorption of dilute streams in monoliths composed of materials with bidisperse structure was developed. A more simplified model in 1D was also used for description of adiabatic bulk adsorption. Breakthrough curves of propylene diluted in helium at three different partial pressures (1.5, 5.6 and 10.0 kPa ) were measured to validate both models.