Study on biochar as desulfurizer for SOFC application

• Published in: Fuel cells (Weinheim an der Bergstrasse, Germany) Vol. 21; no. 5; pp. 430 - 439
• Main Authors: Setiawan, Hendrik, Sakamoto, Mio, Shiratori, Yusuke
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.10.2021
• Subjects: Adsorption; Ammonia; Anodes; Bamboo; biochar; Biogas; desulfurization; Desulfurizing; Electrode materials; Free atmosphere; Hydrogen sulfide; Poisons; Reforming; Silicon dioxide; SOFC; Solid oxide fuel cells; Surface chemistry
• ISSN: 1615-6846; 1615-6854
• DOI: 10.1002/fuce.202100025

The potential of biogas as a source of H2 for the operation of solid oxide fuel cells (SOFC) has received much attention in recent years. However, in order to achieve commercial‐level stability of a biogas‐fueled SOFC system, impurities in biogas such as H2S, which poisons the reforming catalyst and anode material, must be eliminated. In this study, an environmentally‐friendly biogas purification process using biochar was explored. Bamboo (BB) and rice husk (RH) were chosen as starting materials and heat‐treated at 500°C for 120 min in an O2‐free atmosphere to produce BB‐ and RH‐derived biochars, BB‐BC and RH‐BC, respectively, then treated with steam or ammonia. H2S adsorption tests were performed for these biochar samples, and breakthrough capacity (ACPH2S(0)) and total H2S adsorption capacity (ACPH2S) were evaluated. Steam treatment effectively increased ACPH2S(0) and ACPH2S for BB‐BC, however, intense steam treatment had a negative effect, especially for RH‐BC because of the silica exposed on the surface. Ammonia treatment of biochar to form pyridinic N sites on the carbon surface was considerably effective to enhance the performance of a biochar as desulfurizer. By the ammonia treatment of RH‐BC at 900°C, ACPH2S(0) and ACPH2S increased by 2 and 30 times, respectively.