Moisture-Assisted Synthesis and Carbon Dioxide Capture Performance of ZIF-L in Methanol Solution

The leaf-like zeolite imidazolate framework (ZIF-L) with a lamellar structure is an excellent gas adsorption material. It is generally considered that the synthesis of ZIF-L must be carried out in an aqueous solution. In this study, an almost pure ZIF-L crystalline phase with nanoflake morphology was unexpectedly synthesized as the Zn2+ concentration in the methanol solution was greater than or equal to 0.36 M, and the molar ratio of Hmim to Zn2+ was fixed at 4:1. X-ray diffraction was used to characterize the crystalline structure of the product. X-ray absorption fine structure spectra were used to analyze the local atomic structure around Zn. Scanning electron microscopy was used to observe the morphology of products. Through air isolation experiments, it was found that the ambient moisture is a critical factor in determining the final product because the moisture not only penetrated the precursor solution but also participated in the synthesis of the ZIF-L phase. The as-prepared ZIF-L phase exhibits good CO2 adsorption performance. Its CO2 adsorption capacity is 1.09 for ZIF-Zn1, 1.04 for ZIF-Zn2, 1.42 for ZIF-Zn4, and 1.16 mmol/g for ZIF-Zn6 at ambient temperature and normal pressure. This study provides a moisture-assistant approach to synthesize the ZIF-L phase in a non-aqueous solution.