Modeling and simulation of a simulated moving bed for adsorptive para-xylene separation

Abstract

A multi-cell model was developed to analyze the behavior of a simulated moving bed process for adsorptive para-xylene separation from other xylene isomers. A novel technology for a semi-batch mode adsorption experiment was developed and used for fast and accurate data collection. Interaction parameters between different species for a multi-component extended Langmuir isotherm were estimated from single and multi-component adsorption experiments and implemented into the model. The parameters such as porosities, particle density and mass transfer coefficients were obtained from adsorbent analysis and commercial plant operation. To resolve the problem of high dimensionality, a cell-by-cell approach was proposed to solve the model. The recovery and purity of para-xylene as well as the concentration profile calculated from the model were in good agreement with the actual data. The effects of channeling and feed composition change were simulated, and they turned out to be physically meaningful. The simulation model will be used for operation condition optimization, trouble shooting, and productivity enhancement including a configuration change.

Adsorption Equilibrium and Kinetics of the Parex' Feed and Desorbent Streams from Batch Experiments

“…Considering the experimental results summarized in Tab. 1, the saturation capacities are of the same order of magnitude as the results reported by Neves 23 and by Lee et al 13, but higher than those reported by Minceva and Rodrigues 12. p ‐Diethylbenzene has the lowest saturation capacity, which is also in agreement with the data of Neves 23 and Lee et al 13; m ‐xylene, o ‐xylene, and ethylbenzene have lower Langmuir constants than p ‐xylene, p ‐diethylbenzene, and toluene.…”

“…Previous adsorption studies of xylene isomers on faujasites addressed adsorption from the gas phase, e.g., Ba‐X 3, 4, Ba‐Y 5–7, K‐Y 6–11, Na‐Y 5–7) as well as from the liquid phase, e.g., Ba‐exchanged faujasite 2, 12, Ba‐X 4, KBa‐X 13, Na‐X 14, Y 15, Ba‐Y 16, K‐Y 17–19, KBa‐Y 20, 21, Na‐Y 22, and mostly on zeolite Y. In practice, the operation of the SMB in the gas phase requires much larger volumetric flow rates than in the liquid phase, and the recirculation and pressure control of the streams in the gas phase is more difficult to handle than in the liquid phase.…”

Adsorption of C6–C8Aromatics over Ba‐Exchanged Zeolite X at High Temperature

“…The adsorption equilibrium constants are similar to that reported by Minceva and Rodrigues and Lee et al. . The results reported by Lee et al.…”

“…The results reported by Lee et al. on zeolite X followed the order PX > OX > EB > MX > TOL. In this study, the results follow the sequence PX > OX > EB ≈ MX > TOL > Bz.…”

Hybrid Process for o‐ and p‐Xylene Production in Aromatics Plants

“…With all the developments in xylene separation already attained, in particular SMB process optimization in order to increase its performance and efficiency 8, 9, 32, 48–52, advances in xylene separation processes nowadays are able by application of new materials as adsorbents.…”