Synthesis of W-substituted CeO2 powder and its CO2 adsorption under a CO2 atmosphere

We synthesized W-substituted CeO2 (W-CeO2) with a fluorite structure by heating precipitates, prepared from Ce(NH4)(2)(NO3)(6) and (NH4)(6)H2W12O40 aqueous solutions, at 700 degrees C in air. X-ray diffraction and X-ray fluorescence measurements confirmed successful W substitution into CeO2 with a fluorite structure. X-ray photoelectron spectroscopy revealed that the amount of Ce3+ in W-CeO2 was increased by W substitution. The lattice constant of the W-CeO2, as determined by Rietveld analysis, increased with increasing W content because of the greater Ce3+ content in CeO2. Fourier-transform infrared spectroscopy under a CO2-gas flow indicated that the proportion of hydrogen carbonate species on the surface of W-CeO2 with a W/Ce ratio of 1/6 was considerably larger than that of pure CeO2. The CO2 adsorption isotherms measured at 25 degrees C showed that W-CeO2 had a larger CO2 adsorption capacity than that of pure CeO2. Thus, the formation of hydrogen carbonate species improved the CO2 adsorption ability of the W-CeO2. (C) 2018 Elsevier B.V. All rights reserved.