镧钴钙钛矿型催化剂的制备及其催化甲烷燃烧性能的研究
发布时间：2019-06-01 16:30
【摘要】：甲烷催化燃烧是一种高效率、低污染的能源利用和废气处理技术,能够通过催化作用降低燃料的起燃温度和燃烧的峰值温度,提高甲烷燃烧利用率,减少大气污染物的生成。钙钛矿在氧分离、固体氧化物燃料电池和催化燃烧领域都显示了其良好的性能,具有替代贵金属催化剂的潜力。本文制备了La0.6Sr0.4Co0.2Fe00.8O3-δ钙钛矿。采用低温N2物理吸附,X-射线衍射(XRD),氢气程序升温还原(H2-TPR),氧气程序升温脱附(O2-TPD)和X-射线光电子能谱(XPS)表征了其物理化学性质,并考察了低浓度甲烷燃烧催化活性。通过共沉淀法、微乳液法和柠檬酸络合法制备了 La0.6Sr0.4Co0.0Fe0.8O3-δ钙钛矿催化剂,并研究了制备方法对催化剂物理化学性质的影响。通过对比,选择柠檬酸络合法优于共沉淀法和微乳液法。采用柠檬酸络合法制备La0.6Sr0.4Co0.2Fe0.8O3-δ钙钛矿催化剂时,适量的柠檬酸用量会提高催化剂的氧化还原能力和催化性能。当柠檬酸/金属离子摩尔比为1.25形成的钙钛矿晶型更完整,催化剂中的Fe4+和Co3+的还原温度较低,还原性能好,催化剂表面上吸附氧晶格氧之比最大,低温还原性最好,催化活性也最好。采用柠檬酸络合法制备催化剂时,空气气氛和先氮气预处理后空气焙烧的样品活性比在氮气气氛中活性好,空气气氛中柠檬酸自燃放出大量热量,使得制得的催化剂晶型最好,颗粒最分散,催化剂活性最好。采用柠檬酸络合法制备催化剂时,焙烧温度小于700 ℃时,焙烧温度略低,钙钛矿未完全形成,温度大于700 ℃时,催化剂团聚长大,并发生烧结,此时催化剂粒径较大。700 ℃焙烧的样品不仅形成了单一均相的复合钙钛矿氧化物La0.6Sr0.4Co0.2Fe0.8O3-δ催化剂,且该样品低温还原性好,化学稳定性较好,对甲烷的催化燃烧具有较高的催化活性。采用柠檬酸络合法制备Ba掺杂的La0.6Sr0.4Co0.2Fe0.8O3-δ钙钛矿型催化剂时,钡掺杂量对催化剂比表面积影响不大,但会影响了 B4+含量和表面吸附氧浓度,两者对催化活性均有重要影响,在掺杂量为0.1时,反应速率达到了最佳匹配,得到了最好的催化活性。
[Abstract]:Methane catalytic combustion is a kind of high efficiency and low pollution energy utilization and waste gas treatment technology, which can reduce the ignition temperature and combustion peak temperature of fuel, improve the utilization rate of methane combustion and reduce the formation of air pollutants. Perovskite has shown good performance in the fields of oxygen separation, solid oxide fuel cell and catalytic combustion, and has the potential to replace precious metal catalysts. In this paper, La0.6Sr0.4Co0.2Fe00.8O3- 未 perovskite was prepared. Its physicochemical properties were characterized by low temperature N2 physical adsorption, X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), oxygen programmed desorption (O2-TPD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of low concentration methane combustion was investigated. La0.6Sr0.4Co0.0Fe0.8O3- 未 perovskite catalyst was prepared by coprecipitation method, microemulsion method and citric acid complexation method, and the effect of preparation method on the physical and chemical properties of the catalyst was studied. By comparison, the citrate complexation method is superior to the coprecipitation method and the microemulsion method. When La0.6Sr0.4Co0.2Fe0.8O3- 未 perovskite catalyst is prepared by citric acid complexation method, the redox ability and catalytic performance of the catalyst can be improved by proper amount of citric acid. When the perovskite crystal form formed by citric acid / metal ion molar ratio of 1.25 is more complete, the reduction temperature of Fe4 and Co3 in the catalyst is lower, the reduction performance is good, the ratio of adsorbed oxygen to oxygen on the surface of the catalyst is the largest, and the reducibility at low temperature is the best. Catalytic activity is also the best. When the catalyst was prepared by citric acid complexation method, the activity of the sample calcined in air atmosphere and nitrogen pretreatment was better than that in nitrogen atmosphere, and the spontaneous combustion of citric acid in air atmosphere released a lot of heat, which made the crystal form of the catalyst the best. The particles are the most dispersed and the catalyst activity is the best. When the catalyst is prepared by citric acid complexation method, the calcination temperature is slightly lower and the perovskite is not completely formed when the calcination temperature is less than 700 鈩，
本文编号：2490416
[Abstract]:Methane catalytic combustion is a kind of high efficiency and low pollution energy utilization and waste gas treatment technology, which can reduce the ignition temperature and combustion peak temperature of fuel, improve the utilization rate of methane combustion and reduce the formation of air pollutants. Perovskite has shown good performance in the fields of oxygen separation, solid oxide fuel cell and catalytic combustion, and has the potential to replace precious metal catalysts. In this paper, La0.6Sr0.4Co0.2Fe00.8O3- 未 perovskite was prepared. Its physicochemical properties were characterized by low temperature N2 physical adsorption, X-ray diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), oxygen programmed desorption (O2-TPD) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of low concentration methane combustion was investigated. La0.6Sr0.4Co0.0Fe0.8O3- 未 perovskite catalyst was prepared by coprecipitation method, microemulsion method and citric acid complexation method, and the effect of preparation method on the physical and chemical properties of the catalyst was studied. By comparison, the citrate complexation method is superior to the coprecipitation method and the microemulsion method. When La0.6Sr0.4Co0.2Fe0.8O3- 未 perovskite catalyst is prepared by citric acid complexation method, the redox ability and catalytic performance of the catalyst can be improved by proper amount of citric acid. When the perovskite crystal form formed by citric acid / metal ion molar ratio of 1.25 is more complete, the reduction temperature of Fe4 and Co3 in the catalyst is lower, the reduction performance is good, the ratio of adsorbed oxygen to oxygen on the surface of the catalyst is the largest, and the reducibility at low temperature is the best. Catalytic activity is also the best. When the catalyst was prepared by citric acid complexation method, the activity of the sample calcined in air atmosphere and nitrogen pretreatment was better than that in nitrogen atmosphere, and the spontaneous combustion of citric acid in air atmosphere released a lot of heat, which made the crystal form of the catalyst the best. The particles are the most dispersed and the catalyst activity is the best. When the catalyst is prepared by citric acid complexation method, the calcination temperature is slightly lower and the perovskite is not completely formed when the calcination temperature is less than 700 鈩，
本文编号：2490416
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