Incorporation of Cu3BTC2 nanocrystals to increase the permeability of polymeric membranes in O2/N2 separation

Chong Yang Chuah,Tae-Hyun Bae

doi:10.1186/s42480-019-0002-z

Abstract

To increase permeability in O2/N2 separation without compromising selectivity, Cu3BTC2 (or HKUST-1) nanocrystals, which possess well-defined channels and high surface area, were used as the filler for mixed-matrix membrane fabrication. The Cu3BTC2 nanocrystals, which were synthesized at room temperature with a facile method, showed desirable physical properties and porosity comparable to those of a commercial Cu3BTC2 adsorbent (Basolite C300). High-quality mixed-matrix membranes without appreciable defects were successfully fabricated with both Matrimid and polysulfone, which are commercial membrane polymers that suffer from poor permeability. Gas permeation testing revealed that 20 wt% Cu3BTC2 nanocrystals loading dramatically improved the O2 permeability of both polymer membranes (106% for Matrimid and 379% for polysulfone), with modest increases in O2/N2 selectivity. A detailed analysis of diffusivity and solubility showed that the overall O2/N2 diffusion selectivity was improved substantially over that of a neat polymeric membrane with the incorporation of Cu3BTC2 nanocrystals. A comparative study with literature data demonstrated that Cu3BTC2 nanocrystals are far more effective than other metal-organic framework fillers tested to increase permeability in O2/N2 separation.

Highlights

There is growing interest in oxygen-enhanced combustion as a tool to improve energy efficiency in combustion processes typically used in energy production [1, 2]
With the use of Cu3BTC2 nanocrystals as the filler material, we aimed to demonstrate a dramatic enhancement in the gas permeability without compromising the selectivity, which can in turn improve the economic feasibility of a membrane-based O2/N2 separation process
Cu3BTC2 nanocrystals dramatically improved the O2 permeability of polysulfone and Matrimid, which are widely used membrane polymers that suffer from poor permeability

Summary

Introduction

There is growing interest in oxygen-enhanced combustion as a tool to improve energy efficiency in combustion processes typically used in energy production [1, 2]. Nitrogen, which is the largest component of air but does not participate in the combustion reaction, takes up a large amount of heat in combustion processes, leading to a drastic decrease in energy efficiency [1, 2] This decrease is exacerbated by the possible production of nitrogen oxides (NOx), which have negative consequences on the environment such as photochemical smog and acid rain. The O2 content in the feed source must be increased to increase the efficiency of the energy output and to decrease emissions of carbon In this regard, many approaches have been developed to produce an oxygen-enriched stream for these processes.

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Conclusion