Yeol-Lim Lee

Hydrogen production by the water-gas shift reaction using CuNi/Fe2O3 catalyst

Incorporation of both Cu and Ni together into the crystalline lattice of Fe2O3 results in a significant increase in the catalytic activity and also suppresses the methanation reaction in the high-temperature water-gas shift (HT-WGS) reaction. CuNi/Fe2O3 exhibited the highest CO conversion with negligible CH4 selectivity at the extremely high GHSV of 101 000 h−1 (XCO = 85% at 400 °C). The high activity of CuNi/Fe2O3 catalyst is mainly due to the increase in the lattice strain and the decrease in the binding energy of lattice oxygen. In addition, X-ray photoelectron spectroscopy (XPS) results provide direct evidence for the formation of surface CuNi alloy, which plays a critical role in suppressing the methanation reaction. The detailed characterization by powder X-ray diffraction (XRD), XPS, BET, and H2 temperature-programmed reduction (TPR) techniques was used to understand the role of dopants on host iron oxides in the enhancement of catalytic activity for HT-WGS reaction.

Enhancing the catalytic performance of cobalt oxide by doping on ceria in the high temperature water–gas shift reaction

The high temperature water–gas shift (HT-WGS) reaction was performed using a Co–CeO2 catalyst, prepared through a co-precipitation method. The catalyst showed stable activity performance at 400 °C with 90% CO conversion without any side reactions (methanation) at a very high GHSV of 143 000 h−1, which is the highest value reported for the HT-WGS reaction. This remarkable performance is attributed to the superior reducible nature of ceria and the preferential exposure of (220) and (112) facets of CeO2 and Co3O4, respectively. The time-on-stream study substantiates that ceria stabilizes the surface area of the Co–CeO2 catalyst during the WGS reaction compared to the bulk Co3O4.

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 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.