Hydrogen generation from CaCl₂ and MgCl₂ using the chlor-alkali process
摘要
Hydrogen is considered a clean energy carrier with high potential for sustainable energy systems, yet the majority of industrial hydrogen production relies on non-renewable resources such as natural gas, petroleum, and coal, contributing to environmental pollution and greenhouse gas emissions. To address these challenges, alternative electrolytes for hydrogen production in chlor-alkali reactors have been proposed, but comprehensive studies comparing their energetic and sustainable performance are limited. In this study, the production of hydrogen via the chlor-alkali process using CaCl₂ and MgCl₂ salts is experimentally investigated under cell voltages of 5, 7.5, and 10 V, with inlet temperatures of 20 and 45 °C. The experiments were conducted in a membrane-based chlor-alkali reactor equipped with carbon rod electrodes and a Nafion 212 membrane to separate the anode and cathode compartments. Hydrogen production was quantified by the volumetric displacement method, and the corresponding energy efficiencies were calculated based on the applied electrical input. According to the experimental results, the reactor produces 30 mL of hydrogen using CaCl₂ and MgCl₂ at 20 °C and 5 V in durations of 19 and 27.42 min, respectively. At 10 V, the reactor generates the same amount of hydrogen much faster, taking only 2.2 min with CaCl₂ and 10.05 min with MgCl₂. The highest energy efficiency for CaCl₂ is achieved at 45 °C and 7.5 V, with a value of 12.90%, while for MgCl₂, it is observed under the same conditions, with a value of 5.10%. CaCl₂ consistently outperforms MgCl₂ in hydrogen production across varying temperatures and voltages. This study aims to provide a clear comparison of these alternative salts, offering insights into optimizing energy efficiency and sustainability in hydrogen production processes.
Graphical Abstract