Adsorption and Separation of Ethyl Mercaptan from Methane Gas on HNb3O8 Nanosheets

Light mercaptan (R-SH, R = C1–C4) is commonly found in various methane gases. These R-SH compounds are toxic, odorous, and corrosive. On the other hand, they are very important chemical raw materials. Hence, the physical separation of light mercaptan from methane has great economic and environmental benefits. In this paper, a stripping recombination method was adopted to prepare HNb3O8 nanosheet (HNS) aggregation for the adsorption and separation of a mixed gas of ethyl mercaptan (Et-SH) from methane. The composition, morphology, structure, and acidity of the prepared samples were characterized in detail by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), laser Raman spectroscopy (LRS), 1H magic-angle spinning nuclear magnetic resonance (1H MAS NMR), and N2 adsorption and desorption. The cyclic regeneration performance of HNS adsorption and separation of Et-SH from methane gas was studied. Through the analysis of the crystal structure and acidity of HNS, combining characterizations of the adsorbent before and after adsorption and regeneration, and the detection of the regenerated outlet gas, the types of adsorption mechanisms are obtained. Molecular-level adsorption mechanisms of Et-SH on HNS are proposed by density functional theory (DFT) calculations.