| Summary: | 博士 === 國立清華大學 === 化學工程研究所 === 83 === Using fluorite-type oxygen-ion conducting oxide support to
enhance the reducibility and catalytic activity of copper oxide
catalyst is the major purpose of this study. The fluorite-type
oxygen-ion conducting oxide support employed in this work was
yttria-stabilized zirconia (YSZ), of which the yttria content
is 6.8 and 8 mol%. For comparison, γ-alumina was also adopted
as support. All copper oxide catalysts were prepared by using
impregnation method. The physical and chemical properties of
catalyst and support were characterized by temperature-program-
med reduction (TPR), temperature-programmed oxidation(TPO), x-
ray diffraction (XRD), transmission electron microscope(TEM),
electron paramagnetic resonance (EPR), and x-ray photoelectron
spectroscopy (XPS), respectively. The activity test of catalyst
was carried out in a continuous flow reactor and the reactants
were CO and O2. Results showed that oxygen vacancies of YSZ
support can protect the interfacial Cu+ to avoid further
reduction or oxidation during reaction. In the TPR study, it
was found that the surface oxygen vacancies of YSZ support can
sig- ificantly lower the reduction temperature of the
interfacial copper oxide, and the temperature difference is ca.
50℃ as compared with that of γ-alumina supported one. This
phenomenon is associated with the functions of the oxygen
vacancy of YSZ. Results of the activity tests indicated that
CuO/YSZ catalysts can exhibit PM-like behaviors such as light-
off characteristic and hysteresis phenomenon but CuO/γ-alumina
catalysts can not do so. The significant and conspicuous
activity enhancement of the YSZ supported copper oxide has been
ascribed to the modifi- cation of reaction mechanism due to the
surface oxygen vacancy of YSZ. An interfacial active center
composed of an interfacial Cu+ ion and a surface oxygen vacancy
of YSZ and formed by the interfacial metal oxide-support
interaction (IMOSI) was proposed to explain the activity
enhancement.
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