Integrated design, scale-up, and surrogate-based optimization of PSA systems for hydrogen purification from ammonia decomposition

Green hydrogen production from liquid organic hydrogen carriers such as ammonia is a key pathway toward decarbonization and net-zero emissions. However, hydrogen derived via ammonia decomposition must be further purified to meet stringent requirements of some applications, including adoption in fuel cells. This study presents a framework for the design, modeling, and multi-objective optimization of a purification unit based on pressure swing adsorption (PSA). An adsorption model was developed and validated against experimental isotherms and breakthrough data. The validated model was then scaled to industrial conditions to serve as a base-case simulation. A detailed sensitivity analysis was conducted to evaluate the impact of key operational and design variables—including bed length, diameter, pressure, temperature, and flow rate—on four critical performance indicators: hydrogen purity, recovery, productivity, and specific energy consumption (SEC). A surrogate model was trained using high-fidelity simulation data and integrated with the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to generate Pareto-optimal solutions. The surrogate model's predictions were successfully validated against full-order simulations. The optimization results revealed three distinct operating regions, each representing a trade-off between purity, recovery, and energy efficiency. Notably, the proposed design achieves up to 99.99 % hydrogen purity with a recovery of 77.4 %, and SEC values as low as 5.19 MJ/kg H₂. Compared to baseline configurations, the recommended design achieves improvements of 2.78 % in hydrogen purity and 11.11 % in energy efficiency, offering a promising and scalable strategy for ammonia-based hydrogen purification systems. The economic assessment, based on technical performance, estimated the projected cost of purifying hydrogen to 99.99 % concentration using an industrial-scale PSA unit fed by ammonia decomposition. These evaluations suggest a pathway to produce high-purity hydrogen supporting its integration into energy markets.