Hyun-Suk Na

A crucial role for the CeO2–ZrO2 support for the low temperature water gas shift reaction over Cu–CeO2–ZrO2 catalysts

A co-precipitation method was employed to prepare Cu dispersed on CeO2, ZrO2 and CeO2–ZrO2 supports to obtain catalysts useful for the low temperature water gas shift (WGS) reaction. To optimize the Cu–CeO2–ZrO2 catalysts, the CeO2/ZrO2 ratio was systematically changed. The cubic phase Cu–Ce0.8Zr0.2O2 catalyst exhibited the highest turnover frequency and the lowest activation energy among the catalysts tested and its CO conversion was maintained without significant loss during the reaction for 100 h. The enhanced catalytic activity and stability of the co-precipitated Cu–Ce0.8Zr0.2O2 was mainly attributed to an enhanced oxygen mobility and a strong resistance against the sintering of Cu, resulting from a large amount of defect oxygen and the strong interaction between CuO and cubic phase Ce0.8Zr0.2O2.

Highly Active and Stable Pt-Loaded Ce0.75Zr0.25O2 Yolk–Shell Catalyst for Water–Gas Shift Reaction

Multishelled, Pt-loaded Ce0.75Zr0.25O2 yolk-shell microspheres were prepared by a simple spray pyrolysis process for use in the water-gas shift (WGS) reaction. The Pt-loading was optimized, obtaining highly active Pt/Ce0.75Zr0.25O2 yolk-shell nanostructures for the WGS. Of the prepared catalysts, a 2% Pt loading of the Ce0.75Zr0.25O2 yolk-shell microspheres showed the highest CO conversion. The high catalytic activity of the 2% Pt/Ce0.75Zr0.2O2 catalyst was mainly due to its easier reducibility and the maintenance of active catalytic Pt species. The Pt-loaded Ce0.75Zr0.25O2 catalyst microspheres were highly resistant to Pt sintering because of their unique yolk-shell structure. Spray pyrolysis was found to be highly efficient for the production of precious-metal-loaded, multicomponent metal oxide yolk-shell microspheres for catalytic applications.

Preferential CO oxidation over supported Pt catalysts

Preferential CO oxidation reaction has been carried out at a gas hourly space velocity of 46,129 h−1 over supported Pt catalysts prepared by an incipient wetness impregnation method. Al2O3, MgO-Al2O3 (MgO=30 wt% and 70 wt%) and MgO were employed as supports for the target reaction. 1 wt% Pt/Al2O3 catalyst exhibited very high performance (XCO>90% at 175 °C for 100 h) in the reformate gases containing CO2 under severe conditions. This result is mainly due to the highest Pt dispersion, easier reducibility of PtOx, and easier electron transfer of metallic Pt. In addition, 1 wt% Pt/Al2O3 catalyst was also tested in the reformate gases with both CO2 and H2O to evaluate under realistic condition.

A Study on Preferential CO Oxidation over Supported Pt Catalysts to Produce High Purity Hydrogen

To develop preferential CO oxidation reaction (PROX) catalyst for small scale hydrogen generation system, supported Pt catalysts have been applied for the target reaction. The supports were systematically changed to optimize supported Pt catalysts. Pt/Al2O3 catalyst showed the highest CO conversion among the catalysts tested in this study. This is due to easier reducibility, the highest dispersion, and smallest particle diameter of Pt/Al2O3. It has been found that the catalytic performance of supported Pt catalysts for PROX depends strongly on the reduction property and depends partly on the Pt dispersion of supported Pt catalysts. Thus, Pt/Al2O3 can be a promising catalyst for PROX for small scale hydrogen generation system.

The investigation of non-noble metal doped mesoporous cobalt oxide catalysts for the water–gas shift reaction

In this study, we report an investigation of the low temperature water–gas shift (LT-WGS) reaction over a series of non-noble metal doped (Me = Mn, Fe, Co, and Ni) mesoporous Co3O4 catalysts. The effect of metal dopants on the structure and reducibility of the mesoporous Co3O4 oxide was examined using X-ray diffraction (XRD), N2-adsorption/desorption isotherm measurements, and H2-temperature programmed reduction (TPR) measurements. Experimental results revealed that among the Me-doped Co3O4 catalysts, Ni/Co3O4 demonstrated the highest catalytic performance (XCO = 93% with 47% H2 yield at 280 °C). The higher activity of the Ni-doped Co3O4 catalyst was mainly due to its smaller crystallite size (8.6 nm) and strong interaction between Co and Ni, which lead to the higher reducibility of Co3O4 compared to the other metal-doped Co3O4. To further optimize the loading of Ni- over the mesoporous Co3O4, a series of Ni(x%)/Co3O4 catalysts were prepared by varying the Ni-loading in the range of 3 to 15 wt%. Among these catalysts, 5 wt% Ni- was found to be the optimum loading, whereas higher Ni-loaded samples (10 and 15 wt%) showed a decrease in catalytic performance and hydrogen yield during the WGS reaction.

A Study on Cu Based Catalysts for Water Gas Shift Reaction to Produce Hydrogen from Waste-Derived Synthesis Gas

>> Simulated waste-derived synthesis gas has been tested for hydrogen production through water-gas shift (WGS) reaction over supported Cu catalysts prepared by co-precipitation method. CeO2, ZrO2, MgO, and Al2O3 were employed as supports for WGS reaction in this study. Cu-CeO2 catalyst exhibited excellent catalytic activity as well as 100% CO2 selectivity for WGS in severe conditions (GHSV = 40,206h and CO concentration = 38.0%). In addition, Cu-CeO2 catalyst showed stable CO conversion for 20h without detectable catalyst deactivation. The high activity and stability of Cu-CeO2 catalyst are correlated to its easier reducibility, high oxygen mobility/storage capacity of CeO2.