Selectivity

Barrer

Ionic liquid

Organic chemistry

Gas separation

Polymer chemistry

Membrane

Thermogravimetric analysis

Engineering

Catalysis

Composite material

Chemistry

Materials science

Chemical engineering

Polymer

Biochemistry

Journal of Membrane Science

In this work, we synthesized an ionic liquid (IL)/metal organic framework (MOF) composite, 1-ethyl-3-methylimidazolium acetate/copper-1,3,5-benzenetricarboxylate ([EMIM][OAc]/CuBTC) and used it as a filler in a polymer, Pebax, to fabricate novel IL/MOF/polymer mixed matrix membranes (MMMs). CuBTC/Pebax and [EMIM][OAc]/CuBTC/Pebax MMMs having different filler loadings of 10, 15, and 20 wt.% were prepared by solution casting method and characterized using various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Uniform dispersion of MOF and IL/MOF fillers in the MMMs was observed. Incorporation of IL/MOF composite into Pebax significantly improved CO2 permeability and CO2/N2 selectivity of the polymer by 2.5- and 5.5-times, respectively. Gas permeability measurements showed that the MMM having 15 wt.% IL/MOF loading exhibits significantly higher CO2 permeability of 335 Barrer and CO2/N2 selectivity of 176 than the Pebax membrane having CO2 permeability of 135 Barrer and CO2/N2 selectivity of 32. CO2/N2 selectivity of the [EMIM][OAc]/CuBTC/Pebax MMM with 15 wt.% [EMIM][OAc]/CuBTC filler loading was the highest among the selectivity values reported for other types of IL/MOF/polymer MMMs in the literature. All the CuBTC/Pebax MMMs and [EMIM][OAc]/CuBTC/Pebax MMMs that we fabricated in this work exceeded the Robeson's updated upper bound, showing the excellent potential of these novel membranes for CO2/N2 separation.

A novel IL/MOF/polymer mixed matrix membrane having superior CO2/N2 selectivity