Vapor-assisted conversion synthesis of prototypical zeolitic imidazolate framework-8

Abstract

ZIF-8 [Zn(MIM)₂, MIM = 2-methylimidazole] samples were synthesized by a vapor-assisted conversion method with n-heptane, methanol, and DMF, respectively. X-ray diffraction, thermogravimetric analysis, nitrogen (N₂) adsorption, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the properties of the ZIF-8 samples. The particle sizes of the ZIF-8 samples synthesized with methanol, DMF, and n-heptane were 10–20, 60–90, and 30–50 μm, respectively. To our knowledge, this is the first time that ZIF-8 has been synthesized through vapor-assisted conversion with nonpolar n-heptane. For the ZIF-8 synthesis by this method, 0.5 mL of solvent was sufficient, greatly reducing the solvent dosage required compared with a traditional solvothermal method. In our study, on the crystallization of ZIF-8 synthesis by different liquid phases at 50 and 100 °C, we found that the transformation rate from the solid reagents to ZIF-8 phase with n-heptane was faster than that with methanol or DMF.

Keywords:

• n-Heptane
• Vapor-assisted conversion method
• Zeolitic imidazolate frameworks (ZIFs)

Acknowledgments

This work was supported by the National Natural Science Funds (Grant no. 51172153), Program for the Shanxi Province Foundation for Returness.