Selective Electrochemical Regeneration of Aqueous Amine Solutions to Capture CO₂ and to Convert H₂S into Hydrogen and Solid Sulfur

Abstract

Removing CO2 from natural gas or biogas in the presence of H2S is technically challenging and expensive as it often requires separation of both acid gases from the gas, typically using an aqueous amine solution, followed by separation of CO2 from H2S and conversion of H2S into solid S. In this work, the proof of concept of electrochemical, instead of thermal, regeneration of an aqueous amine solution is developed. This invention might be a very promising technology and has several advantages. It has H2S versus CO2 selectivity of 100%, can directly convert H2S into S and H2, and is economically competitive with CO2 desorption energy around 100 kJmol−1 and H2S conversion around 200 kJmol−1. If renewable energy is used for electrochemical regeneration, CO2 emissions due to the CO2 capture process can be significantly reduced.

Keywords

• CO₂ capture
• hydrogen sulfide
• electrochemistry
• regeneration
• amine
• gas treatment