Small-Pore Zeolite Membranes: A Review of Gas Separation Applications and Membrane Preparation

Zishu Cao,Shaowei Yang,Ninad Anjikar

doi:10.3390/separations9020047

Zishu Cao, Shaowei Yang + Show 1 more

Open Access

https://doi.org/10.3390/separations9020047

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Journal: Separations	Publication Date: Feb 9, 2022
Citations: 17	License type: CC BY 4.0

Affiliation: University of Cincinnati, Cleveland State University

Abstract

There have been significant advancements in small-pore zeolite membranes in recent years. With pore size closely related to many energy- or environment-related gas molecules, small-pore zeolite membranes have demonstrated great potential for the separation of some interested gas pairs, such as CO2/CH4, CO2/N2 and N2/CH4. Small-pore zeolite membranes share some characteristics but also have distinctive differences depending on their framework, structure and zeolite chemistry. Through this mini review, the separation performance of different types of zeolite membranes with respect to interested gas pairs will be compared. We aim to give readers an idea of membrane separation status. A few representative synthesis conditions are arbitrarily chosen and summarized, along with the corresponding separation performance. This review can be used as a quick reference with respect to the influence of synthesis conditions on membrane quality. At the end, some general findings and perspectives will be discussed.

Highlights

Zeolites are crystalline microporous aluminosilicates formed by TO4 (T = Si, Al, B, Ti, P, etc.) tetrahedrons
Their uniform pore sizes are defined by their specific crystalline structures
To differentiate different types of zeolites by their crystal framework structure, a three-letter code is given for each zeolite structure by the International Zeolite Association (IZA)

Summary

Introduction

With good control of membrane quality and suppressed crystal growth inside substrate pores, AEI membranes are expected to achieve a separation performance similar to that of SSZ-13. Another important consideration is the influence from third component on membrane performance. There was no CO2/N2 separation-performance report for the most permeable high-quality SSZ-13 membranes from Yu and coworkers [3] These membranes are expected to have the highest CO2 permeance and moderate-to-good CO2/N2 selectivity. The high H2/CO2 selectivity, which was not observed by other researchers for DDR zeolite membranes [118,119], might be caused by a continuous amorphous silica film acting as an effective membrane for H2/CO2 separation.

H2 Separation from Hydrocarbons

Other Separations

Membrane Synthesis

Findings

Conclusions