Biogas use in high temperature fuel cells: Enhancement of KOH-KI activated carbon performance toward H2S removal

• DOI: 10.1016/j.ijhydene.2017.02.021
• Publication Date: 2017-04-11T13:46:40Z
• Authors: Linda Barelli; Gianni Bidini; Nicolas de Arespa...; Laura Pérez; Elena Sisani
• Keywords: Biogas; Carbon fibers; Gas composition

Abstract Activated carbons (ACs) treated with KOH-KI are very effective sorbents for deep H 2 S removal, as required by biogas use in high temperature fuel cell systems. For this application, the performance of a commercial KOH-KI treated AC was investigated through a systematic study based on dynamic adsorption tests. With reference to the composition of a real biogas produced in a wastewater treatment plant located in Barcelona, the present work presents a sensitivity performance analysis on singular and synergetic effects of gas matrix, humidity and oxygen on AC KOH-KI performance. The results revealed a positive role of water (up to 90% of relative humidity (R.H.)) for different gas matrices, enhanced by the simultaneous presence of small percentages of oxygen (2% v ). A relevant influence of gas matrix composition was found (except for the case of oxygen addition to dry inlet streams), specifically in terms of a marked negative effect of CO 2 and a significant sorption capacity increase for high percentage of methane. Sulfur dioxide was not detected in the outlet gas-phase for the investigated operating parameters (O 2 2% v , R.H. 0–90%, H 2 S 100 ppm v , temperature 45 °C). Therefore, even in the case of further oxidation of adsorbed elemental sulfur to SO 2 , this product could be completely removed by AC KOH-KI.