Particle morphology effects on conversion and reaction rate of copper chloride hydrolysis for thermochemical hydrogen production

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.