(760c) Composite Mixed Ionic-Electronic Conducting Materials for Low-Temperature Thermochemical CO2 Splitting and Syngas Generation
To address these limitations, we report a thermochemical cyclic redox scheme which uses a redox-active oxide to split CO2 for CO production followed with methane partial oxidation to produce syngas with 2:1 H2:CO molar ratio. To achieve the effective conversion of both methane and CO2 at low temperatures, we investigated composite mixed ionic-electronic conductive (MIEC) materials. Specifically, two compatible yet structurally distinct MIEC oxides are prepared with different ratios and elemental compositions. It was determined that the lattice oxygen (O2-) transport and donation of the composite materials were enhanced at relatively low temperatures. Moreover, the reactions were catalyzed by active sites dynamically formed on the surface of the oxide materials. The as-prepared and cycled materials were tested by XRD, in-situ XRD, TEM, and EDX. Experimental studies demonstrated that up to 85% methane conversion, 95% CO selectivity in partial oxidation of methane, and 92% CO2 to CO conversion at 700oC without using platinum group metals. The redox stability was tested for 50 cycles, and the results showed the conversion and selectivity remained at a high level as the first cycle. Furthermore, the performance of the redox materials at different temperatures of 600 oC, 650 oC, 700 oC, 750 oC, 800 oC was tested. The effects of the compositions of the composite materials were systematically investigated.