CuO/CeO2 supported on SBA-15 for Preferential Oxidation of CO in Hydrogen Rich Environment
Date Issued
2012
Date
2012
Author(s)
Wu, Chen-Yu
Abstract
Proton exchange membrane fuel cell (PEMFC) has been a powerful energy source due to several advantages such as high energy density, low emission of pollutants and low operation temperature. However, there are still some challenges needed to overcome. For example, the CO impurity in H2 fuel may poison the Pt electrode. During the hydrogen production by steam reforming and water-gas shift, there are still 0.25 %~0.5% CO in flowing gas, and the tolerance limit of Pt alloy anode for CO concentration is around 10-100 ppm. Therefore, it is necessary to eliminate 99% of the CO present in the H2 fuel, and the most effective way has been by preferential oxidation (PROX).
Copper and cerium mixed oxide has been found as a promising catalyst for PROX duo to its high conversion and relative cheap price. Mesoporous silica SBA-15 with uniform 2 D hexagonal arrays of pores and high surface area is a promising support to increase CuO/CeO2 surface area and dispersion. Various amounts of copper oxide were impregnated onto SBA-15.The catalysts were characterized by XRD, N2 sorption isotherm, SEM, TEM, XANES, TPR. The activities of the catalysts were tested in PROX reaction under 0.8 % CO, 0.8 % O2, 50 % H2, and 48.4 % He with a total flow rate of 100 mL/min.
XRD patterns showed that copper oxide formed small particles and well dispersed when the mixed oxide was supported on SBA-15. TPR showed that the formation of large CeO2 can enhance the reducibility of catalyst, The reason may due to the particle size of cerium oxide in the high surface silica support is too small, and it would lower the interface of CuO contact with CeO2 .CuO-CeO2 supported on SBA-15 dehydrated at 900oC gave higher catalytic activity than that supported on 500oC calcined SBA-15, probably due to hydroxyl groups on the surface hinder the active site. The activities of the catalysts were significantly decreased in the presence of H2O, especially the silica supported catalysts. This negative effect may be attributed to the hydrophilic surfaces of silica. Among the supported catalysts, 0.1CuO-0.9CeO2/ 2SBA-15-p-900 catalyst could reach 100% CO conversion at 140oC with O2 selectivity around 70%.
Subjects
PROX
PEMFC
CuO
CeO2
SDGs
Type
thesis
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