High-performance multi-layer composite membrane with enhanced interlayer compatibility and surface crosslinking for CO2 separation

Preparation of CO2 separation membrane with high gas permeance and CO2 selectivity is always desirable. In this work, inspired by pesticides and cosmetics, through the use of a variety of additives, good compatibility between the water-based coating solution of low concentration and the hydrophobic surface of the intermediate layer (or gutter layer) had been achieved. A membrane with high gas permeance and moderate CO2 selectivity was prepared preliminarily, and the synergistic mechanism among various additives was clarified. Then, through simple cross-linking modification of the membrane surface, a multi-layer composite membrane for CO2 separation was prepared with CO2 selectivity being improved greatly. The degree of cross-linking on the membrane surface and the thickness of the cross-linked layer was studied by XPS etching analysis. Separation performance for CO2/N2, CO2/CH4, and CO2/H2 mixture had been tested, and the prepared multi-layer composite membrane exhibited excellent CO2 separation performance. Moreover, the simulated flue gas test showed that the prepared membrane was of good long-term stability and impurity resistance. •Good compatibility between aqueous coating solution and hydrophobic surface of the intermediate layer was achieved.•With the addition of water absorbent, the CO2 permeance of the membrane was increased.•The diffusion selectivity of the membrane for CO2 was greatly improved by simple surface cross-linking.•The prepared multi-layer composite membranes showed certain stability and impurity resistance.