Transforming 3D CAU-10-H into 2D Materials with High Base Stability for Membrane Separation

Two-dimensional (2D) nanomaterials have received a significant research attention owing to their unique chemical and physical properties. These materials not only provide the chemically active sites and exposed surface atoms, but also display the porous nature suitable for their use as membranes for gas separation. In this study, 3D CAU-10-H has been transformed into a novel alkali stabilized 2D CACl-10 (180). Though CACl-10 (180) is similar to AlOOH, it is a novel 2D nanomaterial synthesized by using 4-chloroisophthalic acid and aluminum nitrate nonahydrate, with thermal decomposition at 300 °C. Further, CACl-10 (180) is noted to retain its framework structure in strong alkali solutions, attributed to the alkali-resistant aluminum hydroxide. At the same time, it has been demonstrated that 3D CAU-10-H can also transform into 3D CACl-10 (140) and 3D CACl-10 (130), and the halogen atoms of the ligands (−Cl) affect the alkali stability of the materials. Subsequently, the PVAm-CACl-10 (180)/MPSf mixed matrix membranes were prepared and applied for CH₄/N₂ separation. The developed membrane exhibits the CH₄ permeance of 1647.99 GPU with a CH₄/N₂ selectivity of 3.1. As a result, 2D CACl-10 (180), with a strong alkali stability and an acceptable CH₄/N₂ membrane separation performance, represents a high potential of application in the membrane separation process.