RESUMO
The research of thermochemical CO2 splitting based on perovskites is a promising approach to green energy development. Performance evaluation was performed towards the doped perovskite LaCo0.7Zr0.3O3 (LCZ-73) based two-step thermochemical CO2 splitting process thermodynamically based on the experimentally derived parameters for the first time. The impacts of vacuum pump and inert gas purge to reduce oxygen partial pressure and CO2 heating on the performance parameter η solar-to-fuel have been analyzed. The results showed that at the P O2 of 10-5 bar, non-stoichiometric oxygen δ increased by more than 3 times as the reduction temperature varied from 1000 °C to 1300 °C, however, no significant deviation of δ was observed between 1300 °C and 1400 °C. The reaction enthalpy ranged from 60 to 130 kJ mol-1 corresponding to δ = 0.05-0.40. Comparing the abovementioned two ways to reduce the oxygen partial pressure, the η solar-to-fuel of 0.39% and 0.1% can be achieved with 75% and without heat recovery with the CO2 flow rate of 40 sccm under experimental conditions, respectively. The energy cost for CO2 heating during the thermodynamic process as the n CO2 /n LCZ-73 increases was obtained from the perspective of energy analysis. The ratio of n CO2 /n LCZ-73 at lower temperature required more demanding conditions for the aim of commercialization. Finally, the ability of perovskite to split CO2 and thermochemical performance were tested under different CO2 flow rates. The results showed that high CO2 flow rate was conducive to the production of CO, but at the cost of low η solar-to-fuel. The maximum solar-to-fuel efficiency of 1.36% was achieved experimentally at a CO2 flow rate of 10 sccm in the oxidation step and 75% heat recovery.
