PEI@MOFs thin film nanocomposite (TFN) membrane for efficient CO2 separation

Polyetherimide (PEI) membrane exhibits high CO2 selectivity while suffer from low permeance thus limiting the further application in CO2 separation. Thin film nanocomposite (TFN) membrane which contains a thin selective functional layer with nanomaterials porous fillers is a new class of high-performance membranes. In this work, a series of novel PEI@MOFs TFN membranes were prepared for efficient CO2 separation. The sub-micro scale PEI layers (about 400 nm) with four kinds of MOFs fillers including 3-dimensional MOFs nanoparticles (UiO-66 and MIL-101 (Cr)) and MOFs nanosheets (2-D CuBDC and Zn2(bim)4) were prepared by a simple spin-coating strategy. The properties and CO2 separation performance of the TFN membranes were further studied. The MOFs in PEI increased the diffusion coefficient and selectivity for CO2, at the same time, the ultra-thin functional layer maximized reducing the CO2 transport resistance. As a result, the PEI@MOFs TFN membranes exhibited high CO2 permeance as well as enhanced CO2 separation performance which close to the Robeson upper bound. The PEI@CuBDC TFN membrane exhibited CO2 permeance of 15.6 GPU (3.3 times higher than the neat PEI membrane), and the selectivity of CO2/CH4 reached 39.8 (2.2 times higher than the neat PEI membrane). In addition, the PEI@MOFs TFN membranes showed good thermal and operation stability.