Investigation on Synthesis of CeO₂-stabilized CaO/CuO Composite Nanospheres and Their Thermochemical Energy Storage Characteristics

An integrated Ca/Cu looping thermochemical heat storage process was proposed, employing cyclic calcination/reduction-oxidation-carbonation reactions of CaO/CuO composite materials for hydrogen energy storage. In the energy storage stage, the calcination/reduction reaction occurred between hydrogen and CaO/CuO composite materials, storing hydrogen energy as the thermochemical energy of these materials. In the subsequent energy release stage, the CaO/CuO composite materials underwent oxidation and carbonation reactions stepwise with air and CO₂, releasing the previously stored thermochemical energy as heat. For the CaO/CuO composite materials in the proposed process, a two-step synthesis method was used to prepare CeO₂-stabilized CaO/CuO composite nanospheres. The effect of CeO₂ content on the CaO/CuO composite pellets was studied in a fixed-bed reactor. The results show that all of the CeO₂-stabilized CaO/CuO composite nanospheres exhibited stable oxidation performance over ten cycles. However, the CeO₂ content had a significant impact on the carbonation performance of CeO₂-stabilized CaO/CuO composite nanospheres. With an increase in the CeO₂ content from 20% to 60%, the initial carbonation performance of CaO/CuO composite nanospheres decreased significantly from 0.092 g/g to 0.017 g/g.