Removal of Hydrogen Sulfide (H2S) Using MOFs: A Review of the Latest Developments

Abstract

Removal of hydrogen sulfide (H2S) from gas streams with varying overall pressure and H2S concentration is a long-standing challenge faced by the oil and gas industries. The present work focuses on H2S capture using metal-organic frameworks (MOFs), in an effort to shed light on their potential as adsorbents in the field of gas storage and separation. MOFs hold great promise as they make possible the design of structures from organic and inorganic units but also, they have provided an answer to a long-time challenging objective, i.e., how to design extended structures of materials. Moreover, the functionalization of the MOF's surface can result in increased H2S uptake. For example, the insertion of 1% of a fluorinated linker in MIL-101(Cr)-4F(1%) allows for enhanced H2S capture. Although noticeable efforts have been made in studying the adsorption capacity of H2S using MOFs, there is a clear need for gaining a deeper understanding in terms of their thermal conductivities and specific heats in order to design more stable adsorption beds, experiencing high exothermicity. Simply put, the exothermic nature of adsorption means that sharp rises in temperature can negatively affect the bed stability in the absence of sufficient heat transfer. The work presented herein provides a detailed discussion, by thoroughly combining the existing literature, on new developments in MOFs for H2S removal, and tries to provide insight into new areas for further research.