Efficient catalytic decomposition of CO₂ to CO and O₂ over Pd/mixed-conducting oxide catalyst in an oxygen-permeable membrane reactor

The thermal decomposition of CO₂ to CO and O₂ is a potential route for the consumption and utilization of CO₂. However, this reaction is limited by both the thermodynamic equilibrium and the kinetic barrier. In this study, we reported an innovative catalytic process to decompose CO₂ in an oxygen-permeation membrane reactor packed with a mixed-conducting oxide supported noble metal catalyst, or Pd/SrCo _0.4Fe_0.5Zr_0.1O_3-δ (Pd/SCFZ), which is of high activity in the decomposition of CO₂ into CO and O₂. Pd/SCFZ catalyst was prepared by incipient wetness impregnation of the SCFZ powders with an aqueous solution of PdCl₂, and the CO₂ sorption/desorption property was examined by in situ Fourier transform infrared spectroscopy and temperature-programmed desorption-mass spectrometry technologies. It was shown that there appeared a typical of bridged carbonyls (Pd-CO) on the surface of the Pd/SCFZ catalyst formed after CO ₂ decomposition. Both CO₂ and CO could be detected in the species desorbed from Pd/SCFZ catalyst, which implied that the Pd/SCFZ catalyst could effectively activate the CO₂ molecule. During the catalytic process, furthermore, the activity of the Pd/SCFZ catalyst can self-regenerate by removing the produced lattice oxygen through the dense oxygen-permeable ceramic membrane. At 900°C, this catalytic process attains 100% of CO formation selectivity at 15.8% of CO₂ conversions.