Synergistic and Antisynergistic Intracrystalline Diffusional Influences on Mixture Separations in Fixed-Bed Adsorbers

作     者：Rajamani Krishna 

作者机构：Van’t Hoff Institute for Molecular SciencesUniversity of Amsterdam Science Park9041098 

出 版 物：《Precision Chemistry》 (精准化学（英文）)

年 卷 期：2023年第1卷第2期

页      面：83-93页

学科分类：07[理学] 0703[理学-化学] 0701[理学-数学] 070101[理学-基础数学] 

主　　题：kinetic separations transient uptake microporous crystalline adsorbents Maxwell−Stefan equations thermodynamic coupling uphill diffusion transient breakthrough fixed-bed adsorber 

摘      要：Separations of mixtures in fixed-bed adsorbers are influenced by factors such as(1)selectivity of adsorption,Sads,(2)diffusional time constants,Đi/rc 2,and(3)diffusion selectivity,Đ1/Đ*** synergistic separations,intracrystalline diffusion of guest molecules serves to enhance the selectivities dictated by thermodynamics of mixture *** antisynergistic separations,intracrystalline diffusion serves to reverse the hierarchy of selectivities dictated by adsorption *** both scenarios,the productivities of the desired product in fixed-bed operations are crucially dependent on diffusional time constants,Đi/rc 2;these need to be sufficiently low in order for diffusional influences to be ***,the ratioĐ1/Đ2 should be large enough for manifestation of synergistic or antisynergistic *** synergistic and antisynergistic separations have two common,distinguishing ***,for transient uptake within crystals,the more mobile component attains supraequilibrium loadings during the initial stages of the *** overshoots,signifying uphill diffusion,are engendered by the cross-coefficientsΓij(i≠j)of thermodynamic correction ***,the component molar loadings,plotted in composition space,follow serpentine equilibration *** cross-coefficients are neglected,no overshoots in the loadings of the more mobile component are experienced,and the component loadings follow monotonous equilibration *** important takeaway message is that the modeling of mixture separations in fixed-bed adsorbers requires the use of the Maxwell−Stefan equations describing mixture diffusion employing chemical potential gradients as driving forces.