(350a) Robust Nanostructured Noble Metal/ Ceria/Lanthana Catalysts for Water-Gas-Shift

Noble metal nanoparticles dispersed on oxide supports are widely used as catalysts in fuel processing, chemicals production, and environmental protection. Particularly noble metal/ceria catalyst systems have found much attention due to their excellent activity in partial oxidation and water-gas shift. However, the noble metal nanoparticles suffer from insufficient temperature stability and sensitivity to poisoning in the presence of S-contamination in the reactant feed. Both sintering due to high temperatures as well as poisoning by S-contaminants cause the loss of active surface area and result in irreversible deactivation.

Here, we are reporting on the synthesis, characterization, and testing of robust nanostructured noble metal Au/ceria/lanthana catalysts in Water-Gas Shift (WGS) with S-contaminated syngas feeds. The metal nanoparticles are deposited on nanostructured CeO2 supports through deposition-precipitation or impregnation. Subsequently, La2O3 or La-CeOx is deposited on the supported catalysts. La2O3 has been shown to be an efficient regenerative S-capturing material in the temperature range of interest in WGS. The protective surface modification enhanced thermal stability of the catalyst and enables the catalyst combine simultaneous sulfur capturing with WGS catalysis in a synergistic way.

The catalyst were characterized (TEM, XRD, BET, and TPO/TPR), and tested in cyclic TGA and fixed-bed reactor experiments. WGS activity test in repeated temperature ramps shows greatly improved stability of the active nanoparticle through the surface decoration. First results in repeated sulfidation-regeneration cycles are equally promising, showing fast sulfidation kinetics, large S-capturing capacity, and stable regeneration. Synthesis, characterization, and catalytic activity test will be discussed in detail in the presentation.