A comparative techno-economic analysis of aqueous and anhydrous HCl electrolysis processes

The state-of-the-art aqueous HCl electrolysis process is a well-established process for chlorine production but faces challenges such as limited conversion efficiencies, corrosion, and additional pre- and post-electrolyzer processing steps that add to its cost. This study evaluates whether a recently demonstrated anhydrous HCl electrolysis process is more economically viable than the state-of-the-art aqueous process. A 1D electrolyzer model was developed using Aspen Custom Modeler® and integrated into Aspen Plus® for process modeling. Multiple conversion efficiencies (30.5 %, 50 %, 80 %, and 93.4 %) were analyzed for the anhydrous process, with various heat recovery and heat exchanger configurations assessed using the Net Rate of Return (NRR) to identify the most economical setup. Our results show that while the anhydrous process can incur higher operating costs in some cases, operating at 80 % conversion is more economically viable than the current aqueous electrolysis process, with benefits realized due to simplified post-processing steps, high-purity hydrogen co-production, and increased chlorine production rate. We conclude that the anhydrous HCl process is a viable alternative to its aqueous counterpart with a reasonable pathway for industrial adoption. Finally, we discuss optimizations that will further enhance the cost competitiveness of the anhydrous HCl process, such as improved heat recovery and alternative HCl/Cl 2 separation methods. • 1st comparative TEA of aqueous and anhydrous HCl electrochemical recycling processes. • TEA reveals optimizations via waste heat recovery for the anhydrous process. • Anhydrous process is competitive with current process via higher conversion efficiency and generating hydrogen. • Analysis identifies multiple avenues for future research, including catalyst improvements & membrane separation of HCl/Cl 2 .