| In this thesis, an easy method was used to produce cerium-cobalt binary nanostructured oxides, cobalt-cerium-copper ternary nanostructured oxides and lanthanum-based perovskite nanoporous metal oxides. Precursor alloys which contain cerium and lanthanum elements were fabricated through melting. Then sodium hydro oxide was used to corrode aluminum, and the corrosion products were heat-treated in air at last.We used gas analyzer and temperature programmed control system to perform catalytic tests during carbon monoxide gas flux in a reaction bed. Then characterization methods such as X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, high resolution transmission electron microscopy and BET surface area measurement were used to characterize.The whole experiment is mainly divided into two parts. The first part is about the preparation of cerium-based binary and ternary catalysts and catalytic performance research, and the second part is about the preparation and characterization of lanthanum-based perovskite oxide.In the first part, a series of binary and ternary nanoscale oxide powder materials which contain cobalt, cerium or copper were produced after dealloying and annealing treatment. The first part of the experiment is the preparation of cobalt-cerium binary metal oxides and catalytic performance evaluation. The catalytic results showed that with the increase of cobalt in catalyst, the final conversion temperature of the catalyst declined. When the cobalt-cerium ratio reached 25:75 and 15:85, room temperature catalytic response appeared during the second round of the normal catalytic test. Taking the phenomenon of room temperature response and lower complete transformation temperature into consideration, the catalystst with the Co/Ce ratio of 25:75 (Co1Ce3) is the best in a series of samples. So we tested the selective oxidation in hydrogen atmosphere, and found that the catalyst can only catalyze the oxidation of carbon monoxide and have no catalytic effect on hydrogen gas in the overall process of temperature range. So the Co1Ce3 catalyst has fine selective catalysis for carbon monoxide oxidation in the hydrogen-rich atmosphere. The XPS, XRD and TEM results further confirmed that the Co1Ce3 sample consisted of Co3O4 and CeO2 nanorods with high specific surface area (50.67m2/g).Then we calculated the activation energy of the Co1Ce3 catalyst is 49.26 m2/g based on the Arrhenius equation. The ternary Co-Cu-Ce catalysts are similar to the binary catalysts on the preparation method and test method. There is no much difference according to the results of two kinds of different components, and their total conversion temperature is lower than 150℃. And the addition of copper can not cause the sample to obtain room temperature response. Through characterization of the samples by XRD and TEM, we found that the microstructure of the catalyst is nanorod-like and is composed of cobalt oxide, cerium oxide and cupric oxide.In the second part of the experiment, two kinds of components of the precursor alloys were prepared. They are Al88La6X6 and Al95La2.5X2.5 (X is Fe, Cu, Cr, Mn, Ni) in at%. After corroding aluminum by using 5 M/L sodium hydro oxide, the samples were heated for 2 hours at 800 ℃ in air. Then we obtained lanthanum-based perovskite oxide nanoparticles. Using the method of SEM and TEM characterization for analysis, we found that the de-alloyed precursors of Al88La6X6 can obtain pervoskite oxides after high temperature treatment. The materials are very convenient to get, and we can use pure materials directly. This method is also not difficult to repeat too. What’s more, the process of this method is easy to be controlled so that we can achieve large-scale and high-volume production. |
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