Updating and 24 H Testing of State Key Laboratory of Clean Energy Utilization’s Thermochemical Iodine–Sulfur Cycle Water-Splitting Hydrogen Production System

This paper reports the latest update to and a 24 h continuous operation test of the CEU’s thermochemical iodine–sulfur cycle water-splitting system with a maximum H2 hydrogen production capacity of 1500 L/h. To address challenges such as high energy consumption and severe corrosion in traditional processes, the system was updated and optimized by introducing a small-cycle design, simulated using Aspen Plus software, achieving a thermal efficiency of 53%. Specifically, the key equipment improvements included a three-stage H2SO4 decomposition reactor and an HI decomposition reactor with heat recovery, resolving issues of severe corrosion when H2SO4 boils and reducing heat loss. During 24 h continuous operation in January 2025, the system achieved a peak hydrogen production rate of 1536 L/h and a long-term stable rate of approximately 300 L/h, with hydrogen purity reaching up to 98.75%. This study validates the potential for the scaling up of iodine–sulfur cycle hydrogen production technology, providing engineering insights for efficient and clean hydrogen energy production.