Thermochemical splitting of CO2 using Co-precipitation synthesized Ce0.75Zr0.2M0.05O2-δ (M = Cr, Mn, Fe, CO, Ni, Zn) materials

Abstract

This work reports the investigation of the redox reactivity of Ce0.75Zr0.2M0.05O2-δ (M = Cr, Mn, Fe, Ni, Co, Zn) materials towards thermochemical CO2 splitting (CS) cycle. The Ce0.75Zr0.2M0.05O2-δ materials were prepared via co-precipitation method and the derived materials were characterized to determine the phase/elemental composition and microstructural morphology. The powder X-ray diffraction (PXRD) analysis indicate formation of phase pure Ce0.75Zr0.2M0.05O2-δ materials with no metal or metal oxide impurities. The analysis performed using scanning electron microscopy confirms production of agglomerated roundish particles of Ce0.75Zr0.2M0.05O2-δ materials. Synthesized Ce0.75Zr0.2M0.05O2-δ materials were further tested, using a thermogravimetric analyzer (TGA), to determine their redox reactivity towards CS reactions. The obtained results indicate that all the Ce0.75Zr0.2M0.05O2-δ materials possess better thermal reduction (TR) and CS aptitude as compared to previously studied phase pure ceria and transition metal doped ceria oxides. The obtained results further indicate that, except for Ce0.75Zr0.2Mn0.05O2-δ material, all the other Ce0.75Zr0.2M0.05O2-δ materials were capable of releasing higher amounts of O2 during TR performed at 1400 °C as compared to Ce0.75Zr0.25O2-δ. Overall in ten thermochemical cycles, the Ce0.75Zr0.2Zn0.05O2-δ showed the highest O2 releasing capacity (105.1 μmol/g·cycle) and the Ce0.75Zr0.2Ni0.05O2-δ indicated the maximum CO production aptitude (170.5 μmol/g·cycle).