Experimental testing of adsorbents for H2S removal in industrial applications : A comparative study on lifetime and cost effectiveness of different materials

Abstract: Harmful emissions are a global issue and cause trouble for human health and for the environment. There is a wide variety of pollutants and one pollutant is hydrogen sulfide, H2S, that is a member of the group Volatile Sulfur Compounds. H2S is a compound that is known for its smell of rotten eggs and is detectable by the human nose at very low concentrations. At higher concentrations, H2S is highly toxic and even deadly for humans. It is also a corrosive gas, and can, therefore, cause problems for materials that are being exposed to it. This can be an issue when H2S is present in biogas since it can damage engines or pipes. It can also poison catalysts that are used for methane upgrading. There are different methods of removing H2S from air and common ones are to use adsorption media or catalytic oxidation for gas-solid reactions. The catalytic oxidation is oxidizing the H2S and converts it into elemental sulfur. A problem with these techniques is that they need replacement after some time when they have been saturated. The aim and objectives for this project are to find appropriate materials to test in a test rig that was finalized at the beginning of the project, to compare their lifetime. This was done to find the most cost effective material for H2S removal. The effect of humidity in the air was also examined. Eight different samples were tested. Two of these were activated carbonwithout impregnations and the other six were partial catalytic materials (impregnated carbons or metal oxide based materials). The partial catalytic materials were significantly better than the activated carbons. The lifetimes varied among the partial catalytic materials as well, andare believed to be due to different active compounds on the surfacesand the structure. When running the experiments with 70 % relative humidity, the lifetimes were significantly longer than when the same materials were run for 30 %. A lower concentration of H2S in low relative humidity showed lower or the same loading capacity than higher concentrations. Regeneration was tested for one of the metal based materials with a satisfactory result.