Adsorption and Separation of Ethyl Mercaptan from Methane by Hydroxyl Groups on the Surface of HTiNbO5-Nanosheets.

Abstract

Adsorption and separation of light mercaptan (R-SH, R = C1-C4) from methane gas can effectively improve the utilization efficiency of methane and the resource conversion of organic sulfide. To further investigate the effects of composition and structural characteristics of laminates on desulfurization performance, in this paper, a two-dimensional (2D) HTiNbO5-nanosheet (HTiNbO5-NS) was constructed. In addition, the hydrogen-bonding interaction between the exposed hydroxyl active sites on the surface of HTiNbO5-NS and ethyl mercaptan (Et-SH) was constructed to realize the adsorption and separation of Et-SH from methane gas. The breakthrough adsorption capacity (Cap (BT)) of HTiNbO5-NS is 14.35 mg·g-1 in a micro fixed bed with a space velocity of 6000 h-1. The regeneration desulfurization rate (q) of the 10-cycle regeneration adsorption was ca. 96%. Furthermore, density functional theory (DFT) calculation results show that the S atoms of Et-SH and HTiNbO5-NS with the terminal hydroxyl and bridge hydroxyl have electron cloud covering to form the hydrogen-bonding interaction. In addition, the formation details of this hydrogen-bond interaction are discussed. The effects of Ti on the microstructure, hydroxyl acid, hydroxyl content, surface area, and pore volume of nanosheets were studied to explain the reasons for the differences in the properties of the two kinds of nanosheets. This work broadens the design of 2D niobium-based efficient adsorbents for R-SH based on hydrogen-bonding interaction and is helpful to enrich the application of the hydrogen-bonding interaction.