Control of zeolite framework flexibility and pore topology for separation of ethane and ethylene

Abstract

The discovery of new materials for separating ethylene from ethane by adsorption, instead of using cryogenic distillation, is a key milestone for molecular separations because of the multiple and widely extended uses of these molecules in industry. This technique has the potential to provide tremendous energy savings when compared with the currently used cryogenic distillation process for ethylene produced through steam cracking. Here we describe the synthesis and structural determination of a flexible pure silica zeolite (ITQ-55). This material can kinetically separate ethylene from ethane with an unprecedented selectivity of ~100, owing to its distinctive pore topology with large heart-shaped cages and framework flexibility. Control of such properties extends the boundaries for applicability of zeolites to challenging separations.

Building Zeolites from Precrystallized Units: Nanoscale Architecture

“…It appears to us that zeolite synthesis and applications are ac ontinuous evolving field that is full of surprises and potential applications.Avery recent example [132] is the separation of ethene and ethane with an extraordinary selectivity by using an ew pure silica zeolite (ITQ-55) on the basis of not only the pore diameter but also the framework flexibility.T his should open new insights on flexibilityassisted molecular diffusions.F inally,n ew paradigm changes in the trinomial relationship of zeolite synthesis,s tructure, and reactivity have been put forward by directly preparing zeolite structures that should be adequate for catalyzing predefined particular processes.T his can be achieved by starting with the reaction to be catalyzed and establishing its mechanism. Am imic of the reaction transition state is then synthesized as an organic structure-directing agent (OSDA), and used to prepare the zeolite structure that, by definition, will be able to stabilize the transition state of the desired reaction.…”

SSZ‐27: A Small‐Pore Zeolite with Large Heart‐Shaped Cavities Determined by Using Multi‐crystal Electron Diffraction

“…[24] Thef ramework structure of this zeolite,I TQ-55, consists of heart-shaped cavities exclusively.These 48 T-atom cavities ([8 3 6 8 5 8 4 9 ]) are interconnected via three shared 8-ring windows forming a2-dimensional channel system. [24] Thef ramework structure of this zeolite,I TQ-55, consists of heart-shaped cavities exclusively.These 48 T-atom cavities ([8 3 6 8 5 8 4 9 ]) are interconnected via three shared 8-ring windows forming a2-dimensional channel system.…”

Low Heat of Adsorption of Ethylene Achieved by Major Solid‐State Structural Rearrangement of a Discrete Copper(I) Complex

“…0.3 %o ft he worldst otal energy consumption. [8][9][10][11][12][13] Adsorbent materials show either kinetic or thermodynamic selectivity for adsorbing components of agas mixture, and are used in pressure (PSA) and temperature swing adsorption (TSA) processes to produce high-purity gases.Key parameters for adsorbent materials include heat of adsorption, working-capacity,s electivity,s orption kinetics,a nd tolerance to contaminants. [5][6][7] There has been considerable recent interest in developing materials for both technologies.…”