Discovery of novel zeolites and multi-zeolite processes for p-xylene separation using simulated moving bed (SMB) chromatography

Abstract

We present a multiscale approach for the identification of novel zeolites as well as for the optimization of simulated moving bed (SMB) chromatographic processes for p-xylene separation. Our hierarchical in silico approach pertains to detailed modeling, simulation, and optimization at molecular and process scales. At the molecular scale, it includes geometric-level pore topology characterization, minimum-energy pathway based selectivity prediction, and shape-selectivity based zeolite ranking for separation of xylenes. At the process scale, first principles model-based optimization of industrial-scale SMB process with 24 columns is performed for the selection of top zeolites and optimal process conditions. We develop a generalized mixed-integer nonlinear optimization (MINLP) model which considers both process design and material selection. We also allow for different zeolites to be selected in different columns. The application of the overall framework results in the discovery of several novel zeolites for the most profitable p-xylene separation using SMB chromatography. The top-ranked shape-selective zeolites are OBW, MEL, MWW, MTT, OWE, FER, SZR, IMF, TON and LAU, which have not been considered in the previous literature for p-xylene separation. To that end, we suggest new applications for these zeolites. Our results indicate that significant increase in profit can be achieved by replacing the current adsorbents by MWW and MEL zeolites. Remarkably, a new SMB process with multiples zeolites introduced in different columns

Shape-Induced Selective Separation of Ortho-substituted Benzene Isomers Enabled by Cucurbit[7]uril Host Macrocycles

“…This supports that the cavity of CB7 is responsible for the isomer separation through host-guest interactions with OX. Moreover, other cucurbituril homologs-cucurbit [5]uril (CB5), cucurbit [6]uril (CB6), and cucurbit [8]uril (CB8)-were also tested. For CB5 and CB6, there was no obvious capacity for three xylene molecules.…”

“…(COFs), porous organic cages (POCs), and porous coordination polymers (PCPs), has proved to be quite efficient for the separation of disubstituted benzene isomers. 4,5,[7][8][9][10][11][12][13][14][15][16][17][18] Nonporous adaptive crystals (NACs), which are mostly based on pillararenes, have achieved excellent selective guest separation due to their unique pillar-like structure and extensive host-guest properties. [19][20][21][22][23][24][25] However, in all the cases of solid-vapor adsorption separation, the vapor production and desorption processes need high temperature and high pressure, which means steep energy requirements.…”

Interdisciplinary Research on Designing Engineering Material Systems: Results From a National Science Foundation Workshop

“…[34], in which the application of topology optimization methodologies is well suited to both the macro and microscale. Other approaches include the work of Hasan et al [35], who have developed a multiscale computational framework for the concurrent simulated moving bed process optimization and the identification of novel zeolites. Their approach combines discovery or selection of materials process systems to screen large databases of candidate materials with certain properties.…”

Mathematical modeling and parameter estimation of MFI membranes for para/ortho‐xylene separation

“…In this article, we focus on the separation of xylene isomers, which is one of the most energy‐intensive separation processes, 23,24 currently accomplished by crystallization 25,26 or adsorption 27‐33 . Separation via membranes has long been studied as a substitute for these technologies, 34‐43 and progress have been achieved based on b‐oriented MFI membranes prepared by gel‐free secondary growth of nanosheets 16,44 .…”

“…In this article, we focus on the separation of xylene isomers, which is one of the most energy-intensive separation processes, 23,24 currently accomplished by crystallization 25,26 or adsorption. [27][28][29][30][31][32][33] Separation via membranes has long been studied as a substitute for these technologies, [34][35][36][37][38][39][40][41][42][43] and progress have been achieved based on boriented MFI membranes prepared by gel-free secondary growth of nanosheets. 16,44 A mathematical model that accounts for diffusion through the MFI layer, defects, and support layer, and mass transfer from the vapor bulk phase to the membrane surface is developed.…”