Highly efficient SO3Ag-functionalized MIL-101(Cr) for adsorptive desulfurization of the gas stream: Experimental and DFT study

Abstract

In this research, an adsorbent with manifold interplay sites for the adsorption of sulfur components is developed in a silver ion functionalized Cr3+ based metal-organic framework (MIL-101(Cr)-SO3Ag). The adsorption performance of MIL-101(Cr), MIL-101(Cr)-SO3H, and MIL-101(Cr)-SO3Ag was evaluated in dynamic adsorption system in terms of its adsorption capacity. MIL-101(Cr)-SO3Ag could interact with H2S through multiple ways which performed about 4 times higher adsorption capacity (96.75 mg/g) rather than MIL-101(Cr); further, the high adsorption capacity of MIL-101(Cr)-SO3Ag was almost unchanged after five successive adsorption–desorption cycles, making it a potential adsorbent for an efficient desulfurization process. Consequently, the density functional theory (DFT) was performed to better understand the adsorption mechanism of H2S. The results showed that the MIL-101(Cr)-SO3Ag could increase adsorption energy (Ead) of H2S, almost ten/two times more than that of the pure/SO3H-modified linker, showing the exiting effects of Ag atom for efficient adsorption capacity of H2S. According to the natural bond orbital analysis (NBO), the larger amount of charge on interacting atoms (Ag and S) reveals that the electrostatic forces are the primary reason for the adsorption of H2S on MIL-101(Cr)-SO3Ag. Also, the net charge is mainly transferred from LPsulfur to LPAg∗, which could remarkably amplify the interaction of H2S with Ag atom.