▎ 摘　　要

NOVELTY - Preparing graphene-assisted metal organic framework membrane material, comprises (i) selecting two-dimensional porous graphene as substrate material, washing it many times with deionized water and acetone, drying, and calcining in air at 250-350 ℃ for 8-16 hours to obtain an activated graphene substrate, (ii) grafting functional groups of aromatic carboxylic acid derivative (I) on the surface of the activated graphene substrate to obtain a modified graphene substrate, and (iii) placing the modified graphene substrate obtained in step (ii) in a reaction kettle, adding zinc nitrate aqueous solution, heating at 100-140 ℃ for 5-12 hours, adding 2-methylimidazole aqueous solution and benzodimethylimidazole aqueous solution, continue stirring for 12-24 hours, washing with methanol, and drying to obtain graphene-assisted ZIF-8 (2-methylimidazole zinc salt) membrane material. USE - The graphene-assisted ZIF-8 membrane material is useful for extracting helium from natural gas (claimed). ADVANTAGE - The graphene-assisted hybrid ZIF-8 membrane material efficiently extracts helium from natural gas, has excellent stability, and excellent separation selectivity and permeability for helium in helium/nitrogen and helium/methane; has simple and feasible preparation method, and is suitable for large scale production. DETAILED DESCRIPTION - Preparing graphene-assisted metal organic framework membrane material, comprises (i) selecting two-dimensional porous graphene as substrate material, washing it many times with deionized water and acetone, drying, and calcining in air at 250-350 ℃ for 8-16 hours to obtain an activated graphene substrate, (ii) grafting functional groups of aromatic carboxylic acid derivative of formula (I) on the surface of the activated graphene substrate to obtain a modified graphene substrate, and (iii) placing the modified graphene substrate obtained in step (ii) in a reaction kettle, adding zinc nitrate aqueous solution, heating at 100-140 ℃ for 5-12 hours, adding 2-methylimidazole aqueous solution and benzodimethylimidazole aqueous solution, continue stirring for 12-24 hours, washing with methanol, and drying to obtain graphene-assisted ZIF-8 (2-methylimidazole zinc salt) membrane material. R1-R3= H, CH3, and OCH3.