This study investigates the hydrolysis process of the thermochemical copper-chlorine (Cu-Cl) cycle of hydrogen production, specifically the influence of CuCl₂ particle morphology and size on conversion and reaction rates. Effects of drying, crushing, and crystallization of particles are considered. CuCl₂ samples with average particle diameters of 95 µm (dried), 27 µm (crushed), and 230 µm (crystallized) were tested in a semi-batch fixed bed reactor at 390°C. Crystallization using HCl as an anti-solvent yielded flaky agglomerated particles and achieved up to 97% conversion, outperforming dried material and closely matching the crushed sample. Kinetic modelling with a shrinking core model (SCM), for both spherical and cylindrical geometries, identified gas film diffusion as the dominant resistance for the smallest sizes of crushed and crystallized particles. X-ray diffraction indicated the formation of CuCl as a side product. The findings established crystallization as a promising approach to facilitate the hydrolysis process. • Particle size and morphology significantly impact CuCl 2 hydrolysis conversion rates. • Crushed CuCl 2 showed superior conversion compared to dried and crystallized forms. • Crystallised CuCl 2 conversion rates increased with decreasing particle size. • Kinetic data for hydrolysis best aligns with the cylindrical shrinking core model.
Radwan et al. (Wed,) studied this question.