Advances on research of H2S removal by deep eutectic solvents as green solvent

Abstract

H₂S in natural gas and other industrial gas is seriously harmful to human health, environmental protection and the downstream industries. Efficient purification of H₂S containing gas is the basic process in the chemical industry. Benefiting from multiple advantages, deep eutectic solvents (DES) can be used as tailor-made green solvents, and have been booming in the fields of harmful gas removal and fuel oil desulfurization. Furthermore, significant scientific research of DES in desulfurization and purification of natural gas has accelerated the process of its practical application. This paper systematically summarizes and analyzes the removal mechanism, impact factors and challenges of DES as emerging green solvent in H₂S absorption and conversion. Strategies on H₂S removal by DES generally fall into two categories: physical absorption and chemical conversion. Although the chemical conversion of H₂S by DES has been less studied compared with the physical absorption, it presents great application potential. At present, the research on H₂S removal by DES is still in the initial stage. Therefore, it is necessary to further study the mechanism of H₂S removal and construct the relationship between structural properties and desulfurization performance of DES, thereby to solve the issues of sulfur blockage and low quality of sulfur paste which is suffered by conventional liquid redox desulfurization solvent system. Additionally, the methods for efficient solvent regeneration and recycling remain to be explored out to promote the practical application of iron-based DES in the field of gas desulfurization.