LCA analysis and quantification of adsorption performance of Kanuma clay by simultaneous adsorption of H₂S and NH₃

In recent years, fuel cell (FC) applications have shown promise in contributing to the abatement of greenhouse gas (GHG) emissions, thereby expanding the demand for hydrogen fuel. Currently, non-renewable sources such as fossil fuels are the primary source of hydrogen. Therefore, for mitigating the GHG emissions during the hydrogen production phase, the focus has been directed toward biomass-derived hydrogen (Bio-H2) production processes. In this study, the environmental impact of Bio-H2 production from sewage sludge has been discussed. The bio-syngas contain various impurities, such as H2S, HCl, and NH3. These impurities could damage the performance of the FC operation. Our previous experimental studies have proposed the use of hydroxyl aluminum silicate clay (HAS-Clay) as an adsorbent in the impurity removal process. HAS-Clay can adsorb a significant amount of H2S by physisorption and is an environment-friendly adsorbent. However, it was found that NH3 decreased the adsorption performance of HAS-Clay. The life cycle assessment revealed that any reduction of eco-burden would be less obtained. Therefore, in this study, Kanuma clay (Kc), which is a natural resource, was used to first adsorb NH3 and aim for maintaining the adsorption performance of HAS-Clay. Kc adsorption capacities of H2S and NH3 have been obtained. However, the adsorption capacity in the simultaneous adsorption of H2S and NH3 has never been investigated. Thus, in this study, the simultaneous adsorption of H2S and NH3 was conducted using an adsorption column with the adsorbents as Kc and HAS-Clay. Finally, the environmental burden of the system was assessed.