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Preparation, Characterization and the Application of CeO2-Co3O4 Catalyst in Low-temperature CO Catalytic Oxidation

Author: HouXiaoDong
Tutor: ZhaoYongXiang;WangYongZuo
School: Shanxi University
Course: Applied Chemistry
Keywords: Co3O4 CeO2-Co3O4 CO oxidation Water resistance
CLC: O643.36
Type: Master's thesis
Year: 2008
Downloads: 223
Quote: 1
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Abstract


Flurry CO low-temperature catalytic oxidation (often) have important practical value in many ways, such as for the underground mine the filter self and the fire self-help respirator CO gas sensors, closed CO 2 < / sub> CO lasers as well as a closed system to eliminate. Meanwhile, due to the reaction system, the theoretical study of CO oxidation is also often used as a probe reaction to study the oxidation catalyst, in order to reveal the relationship between the structure and properties of the catalyst, and to explore the reaction mechanism. Co 3 O 4 as a non-noble metal catalysts for low-temperature catalytic oxidation of CO in recent years has become one of the hot. Showed a very high catalytic activity, but Co 3 O the defects and poor thermal stability and water resistance 4 presence of a catalyst. In this paper, for the of CeO 2 -Co 3 O 4 catalyst preparation, characterization and CO in the low-temperature catalytic oxidation. First examine the immersion method, co-precipitation method and sol-gel method in three different preparation methods affect the performance of its low-temperature CO oxidation, and then focuses on the immersion method doped CeO 2 Co 3 O 4 2 - physical adsorption, TEM, TPR, FT-IR characterization methods. The structure of the catalyst system, by contrast, doped CeO 2 before and after the changes in the structure of the catalyst, and water resistance differences of CeO 2 -Co < / sub> O 4 catalyst has excellent water resistance possible reasons to explore. The main results and conclusions are as follows: 1. By comparing the impregnation, co-precipitation method, sol-gel method CeO 2 -Co 3 O 4 catalyst for CO oxidation performance found prepared by impregnation of CeO 2 content of 5% CeO 2 -Co 3 O 4 catalysts for CO oxidation minimum ignition temperature, the highest catalytic activity; 2. Prepared by impregnation calcination temperature CeO 2 content of 5% CeO 2 -Co 3 O 4 catalyst for CO oxidation performance impact was observed that the 400 ° C calcined CeO 2 content of 5% CeO 2 -Co 3 O < sub> 4 catalysts for CO oxidation has the minimum ignition temperature, the highest catalytic activity; ignition temperature rise from the high-temperature calcination of the catalyst, the decrease in activity, especially 800 ° C calcined catalytic activity was significantly decreased, the ignition The temperature reached above 100 ℃; 3. The CeO 2 doped Co 3 O 4 catalyst structure as well as low-temperature CO catalytic oxidation performance impact, and combined with a series of characterization means of CeO 2 -Co 3 O 4 catalyst has good catalytic activity and stability are explained; For CeO 2 -Co 3 O 4 catalysts exhibit very high water resistance gives a possible reason. Draw the following main results: 1). Room temperature, and the presence of water under the conditions of phase For the single component Co3O 4 catalyst of CeO 2 -Co 3 O 4 < / sub> catalyst has high catalytic stability and activity; For the pure CeO 2 catalyst performance is poor. 2). CO oxidation to water resistance investigation found that when the raw material gas in the water content of 0.6%, room temperature, single component Co 3 O 4 catalyst and CeO 2 -Co 3 O 4 catalyst stability than the poor, just to maintain the CO complete conversion of 20 min, but when the reaction temperature is increased to 110 ° C Co 3 O 4 catalyst for the complete conversion of CO increased to about 100 min, the while of CeO 2 -Co 3 O 4 CO catalyst completely transformed the time it reached at least 8400 min, exhibit excellent water resistance. For the pure CeO 2 catalyst for CO conversion rate is poor; 3). XRD, TEM, N 2 -adsorbtion TPR, FT-IR characterization methods found, compare Co 3 O 4 catalyst, CeO < sub> 2 -Co 3 O 4 catalyst has a smaller particle size, a larger surface area, Co 3 O 4 spinel structure of CeO 2 by highly dispersed catalyst exists because of CeO 2 doped CeO < sub> 2 and Co 3 O 4 interaction between these characteristics of CeO 2 -Co O 4 high catalyst activity, stability, and water resistance have contributed. The main thing is detected in the reaction exhaust to a trace amount of H 2 and show that the water gas shift reaction in water resistance that may occur during the experiment, but in the single component Co 3 O 4 catalyst examine not detected H 2 , the results show that the CeO 2 doped promote the water-gas shift reaction occurrence of this reaction may be of CeO 2 -Co 3 O 4 catalyst has excellent water resistance more direct reason.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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