Experimental Study on the Mechanism and Kinetics of CuCl₂ Hydrolysis Reaction of the Cu–Cl Thermochemical Cycle in a Fluidized Bed Reactor

Abstract

Hydrolysis of CuCl 2 is the water splitting step of the Cu−Cl thermochemical cycle, where CuCl 2 reacts with steam to produce Cu 2 OCl 2 and HCl. In the present work, this gas−solid reaction was investigated to understand the mechanism and kinetics. Experiments were conducted in a semibatch fluidized bed reactor to study the effect of temperature (275−375 °C), steam mole fraction (0.4−0.9), and reaction time (0−3 h). The challenges due to the hygroscopic nature of the reactant, product agglomeration, and multiple side reactions to achieve smooth and consistent reactor performance were overcome by the addition of inert additives during fluidization. The analysis of the mechanism showed that the desired product Cu 2 OCl 2 is formed initially and further undergoes decomposition to CuO and CuCl 2 . Also, with increasing temperatures, the yield of Cu 2 OCl 2 decreases because of the formation of CuCl from reactant decomposition. The results indicate that a minimum steam mole fraction of 0.5 is required to prevent the formation of side product CuCl in the temperature range of 300−325 °C. The minimum steam requirement for maximum yield to Cu 2 OCl 2 was found to increase with increase in temperature.

Cu–Cl Thermochemical Water Splitting Cycle: Probing Temperature-Dependent CuCl2 Hydrolysis and Thermolysis Reaction Using In Situ XAS

“…The formation of CuO was also observed in fixed-bed reactor experiments, at high S/Cu or reaction duration (25,27). Thus, structural similarity and better long-range ordering drives the rearrangement of ions in lattice of Cu 2 OCl 2 , leading to the formation of more stable CuO and CuCl 2 when subjected to thermal treatment for prolonged duration.…”

“…The excess amount of steam requirement is unfavourable to process efficiency. The hydrolysis step has been modelled theoretically [22] and performed experimentally also [23][24][25][26][27][28] to investigate in detail the effect of steam/Cu ratio on experimental yield. For solid-/liquid-phase reactions, reactor configuration also plays an important role in deciding the course of mixing of reactants, thus shaping the reaction kinetics and yield.…”

“…For solid-/liquid-phase reactions, reactor configuration also plays an important role in deciding the course of mixing of reactants, thus shaping the reaction kinetics and yield. Different reactors such as fixed bed [23][24][25], spray [21,26] and fluidized bed [27,28] were employed for CuCl 2 hydrolysis. Fixed-bed hydrolysis of CuCl 2 is associated with drawbacks of poor contact between reactants and creation of (1.1)…”

“…However, Ferrandon et al [21,26] showed that these limitations of fixed bed could be overcome if reactants are sprayed and achieved maximum phase-pure yield at lower steam/Cu ratio of ~ 20 under reduced pressures in a spray reactor. Similarly, Thomas et al [27] investigated the said reaction using a fluidized-bed reactor and revealed that the formation of side product CuCl occurs initially depending on temperature and steam content. Using a fluidizedbed reactor, the maximum yield of the desired product was achieved in range of 300-325 °C at a minimum steam mole fraction of 0.5 within 20-40 min.…”

Nuclear hydrogen production for industrial decarbonization: Creating the business case for the near term

“…Internal stakeholders include power plant and cogeneration facility owners, operators as well as regulators and they work as partners who have both high interest and influence. The power plant owners/ operators act as the nuclear hydrogen project developer, and their role includes feasibility studies, process design Research, development and demonstration projects are in progress on indigenous water 11 and steam electrolyser development, 12 intermediate temperature thermochemical cycles 13,14 (eg, Cu-Cl cycle) and high-temperature thermochemical cycles (eg, I-S process and its variants 15 ). Development of advanced high-temperature molten salt or molten metal cooled reactor (HTR) for supporting high-temperature nuclear hydrogen production and other industrial applications is also being pursued.…”