The Reversible Removal of SO₂ by Amino Functionalized ZIF8 with 5-Aminotetrazole via Post-Synthesis Modification

Abstract

The post-synthesis modification is a highly efficient method for the modification of Metal-organic framework (MOF) materials, which has been used to synthesize MOF materials purposefully that cannot be prepared by direct synthesis and impregnation method. In this work, amino modified ZIF8 with 5-aminotetrazole was prepared by the post synthesis modification method and was employed to reversibly remove SO2 from flue gas. Based on the characterization and analysis of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and Brunner Emmet Teller (BET), it was found that the functionalized ZIF8 (Zn(5-ATZ)1.5) was a microporous material with a two-dimensional nano-layered structure. According to the SO2 adsorption experiments, the adsorption capacity of SO2 at the concentration of 1.6% vol can reach to 122 mg/g under the optimal conditions (25 °C, 2865 h−1). Five successive adsorption-desorption experiments exhibited that Zn(5-ATZ)1.5 had excellent regeneration performance. The characterization results of Raman Spectra (Raman) and X-ray photoelectron spectroscopy (XPS) as well as the DFT simulation calculations revealed that SO2 mainly interacted with Zn(5-ATZ)1.5 by hydrogen bonds between O of SO2 and amino H in the Zn(5-ATZ)1.5, and the interaction of SO2 with amino N and 5-aminotetrazole N by forming a non-covalent charge transfer complex. This work suggested that Zn(5-ATZ)1.5 is an excellent potential sorbent for SO2 removal.

Keywords

• post-synthesis modification
• ZIF8
• sulfur dioxide
• flue gas
• 5-aminotetrazole