Preparation of ZIF-62 polycrystalline and glass membranes for helium separation.

Defects among the grains of MOF polycrystalline membranes lead to non-selective gas transport, thereby reducing their selectivity in gas separation. In this work, ZIF-62 polycrystalline membranes with a well-intergrown structure were prepared on MXene-modified supports. Subsequent thermal treatment transformed the membranes into glass membranes, effectively eliminating non-selective defects at grain boundaries. Due to the incorporation of the MXene film and the vertical positioning of the support during the solvothermal process, only a minimal portion of the glass melt infiltrated into the porous support. Across the temperature range of 303 K–423 K and pressure range of 1 bar–3 bar, the ZIF-62 glass membranes showcased superior helium separation property and long-term chemical stability (resistant to CO 2 and H 2 O). The helium permeance reached approximately 51 GPU, with selectivities against N 2 and CH 4 being 17.4 and 13.9, respectively, outperforming current MOF membranes. [Display omitted] • Zinc ions are absorbed and intercalated into a thin film of the 2D material MXene. • Well-intergrown ZIF-62 membranes are prepared on MXene modified Al 2 O 3 supports. • ZIF-62 polycrystalline membranes melt to glass membranes upon a thermal treatment. • The infiltration of the glass liquid into supports has been effectively prevented. • ZIF-62 glass membranes exhibit great helium separation performance. [ABSTRACT FROM AUTHOR]