Solar hydrogen production via perovskite-based chemical-looping steam methane reforming

Abstract

Solar thermochemical cycle is considered a promising strategy for hydrogen production. The reaction process and oxygen carrier (OC) are the key issues for solar hydrogen production. In this study, a solar-driven chemical-looping steam methane reforming (S-CL-SMR) process by using perovskite as the oxygen carrier is proposed. In this process, the heat required by the endothermic reduction is supplied by solar heat, and the heat is converted into the chemical energy of solar fuels. Perovskites La1−yCayNi0.9Cu0.1O3 were synthesized and characterized. Meanwhile, the reactivity was studied via thermogravimetry analysis at 400 °C for reduction, and 900 °C for re-oxidation. The results show that the reactivity of the La1−yCayNi0.9Cu0.1O3 is improved as the calcium substitution increases. In the reduction reactor, the fractional oxidation of La0.1Ca0.9Ni0.9Cu0.1O3 reaches to 0.61, and the methane conversion is about 52% with 60% CO selectivity. In the steam reactor, oxygen vacancies and reduced metal ions (Ni2+ and Cu2+) in doped perovskites can provide more active sites to break chemical bonds of HO. It is found that La0.1Ca0.9Ni0.9Cu0.1O3 has the best reactivity, regenerability and high resistance to carbon deposition among the synthesized perovskites. Our study is expected to provide a promising potential for hydrogen production by mid-temperature solar heat.