【作者】 刘伟；

【导师】 罗来涛；

【作者基本信息】 南昌大学 ， 工业催化， 2007， 硕士

【摘要】 甲烷催化燃烧可降低污染气体（CO，NO_x）和未充分燃烧烃类的排放而日益受到重视。长期以来，贵金属催化剂尽管拥有良好的催化活性，但由于价格高昂、资源匮乏，从而制约其应用，研制一种高活性、价格低廉的催化剂就显得很有必要。钙钛矿型La_0.8Sr_0.2CoO₃复合氧化物具有较高的活性、稳定性和价格低廉而被受人们关注，然而La_0.8Sr_0.2CoO₃复合氧化物需要较高的焙烧温度才可形成，从而导致晶粒较大和比表面积较低（＜5 m²／g）而制约其应用。因此，寻找一种大比表面积La_0.8Sr_0.2CoO₃复合氧化物的制备方法具有一定的研究价值。本文采用丙氨酸溶液燃烧法、丙烯酰胺-丙氨酸法、丙烯酰胺-氨基乙酸法、环氧丙烷法等方法制备La_0.8Sr_0.2CoO₃复合氧化物，以CH₄催化燃烧为探针反应，研究了不同制备方法、有机燃料、有机燃料与氧化剂的化学计量比、稀土金属离子（Ce、Nd）的A位掺杂、过渡金属离子（Ni、Cu）的B位和焙烧温度对La_0.8Sr_0.2CoO₃复合氧化物催化剂甲烷催化燃烧性能的影响，采用XRD、FI-IR、比表面积测定、H₂-TPR等技术对催化剂进行了表征。1．研究了丙氨酸溶液燃烧法、丙烯酰胺-丙氨酸法、丙烯酰胺-氨基乙酸法、环氧丙烷法等制备方法对La_0.8Sr_0.2CoO₃催化剂甲烷催化燃烧性能的影响。结果表明，丙氨酸溶液燃烧法制备的复合氧化物催化剂表现出最好的甲烷催化燃烧活性，其半转化温度(T₅₀)和完全转化温度(T₁₀₀)分别为470℃和550℃，这是由于该法所制的催化剂平均晶粒度较小、表面和氧空穴处的化学吸附氧更容易移动、表观活化能较低所致。2．采用溶液燃烧合成法制备了La_0.8Sr_0.2CoO₃钙钛矿型复合氧化物，考察了丙氨酸、氨基乙酸和丙三醇等有机燃料对催化剂结构和CH₄催化燃烧活性的影响。结果表明，不同有机燃料所制La_0.8Sr_0.2CoO₃复合氧化物均具有较大比表面积，有机燃料对催化剂的结构和性能有较大的影响，其中以丙氨酸有机燃料制备的复合氧化物活性最好。3．以D，L-丙氨酸为有机燃料，考察了有机燃料与氧化剂的化学计量比（φ）对催化剂结构和性能的影响。实验结果表明，它们的结构和性能随φ的不同而变化，当φ=1.52时所制备的催化剂活性最好，T₅₀和T₁₀₀分别为460和540℃。4．采用Nd、Ce和Ni、Cu分别取代La_0.8Sr_0.2CoO₄复合氧化物A位La离子、掺杂B位中Co离子，结果表明，Nd、Ce和Ni、Cu的掺杂均不能提高La_0.8Sr_0..2CoO₃催化剂CH₄催化氧化反应活性，其活性顺序为La_0.8Sr_0..2CoO₃＞Ce_0.8Sr_0..2CoO₃＞Nd_0.8Sr_0..2CoO₃＞La_0.8Sr_0.2Co_0.5Ni_0.5O₃＞La_0.8Sr_0.2Co_0.5Cu_0.5O₃。5．考察了焙烧温度对La_0.8Sr_0.2CoO₃复合氧化物催化剂甲烷催化燃烧性能的影响。结果表明，不同焙烧温度制备的La_0.8Sr_0.2CoO₃复合氧化物催化剂均具有钙钛矿结构，700℃焙烧的催化剂具有较大的比表面积和较强的还原性能，其甲烷催化燃烧性能较好。更多还原

【Abstract】 Catalytic combustion has attracted much attention due to high combustionefficiency as well as low emission of exhaust gas such as CO, NO_x and unburnedhydrocarbons. For long time the supported noble metal catalysts have been generallyused for methane combustion. However, supported noble metal catalysts, althoughwith outstanding activity, are not fully satisfactory based on high price and scarceresource. Therefore there is a strong demand for the development of high activity, andlow-cost catalysts for the combustion of methane. Perovskite LaCoO₃ has beenextensively studied due to high catalytic activity for methane combustion and highthermal ability. However, the high calcination temperature of the preparedLaCoO₃catalysts inevitably leads to large crystallite size and lower specific surfacearea of the catalysts （less than 5 m²/g）, so the potential applications of these materialsas catalysts are limited. Therefore, in order to increase the specific surface area of theperovskite-type catalysts, the new synthesis method of the catalysts will be required.In the paper, a series of La_0.8Sr_0.2CoO₃ catalysts were prepared by differentsynthesis methods and used successfully for the methane combustion. The selectedtechniques included the alanine solution combustion method, polyacrylamide-alaninegel method, polyacrylamide-glycine gel method and epoxide gel method. The effectsof organic fuels, coefficient ofφ, rare earths （Nd,Ce）, transition metals （Ni,Cu） andcalcination temperature of catatlysts on methane combustion were studied. Theprepared samples were characterized by means of XRD, FI-IR, BET and H₂-TPRmethods.1. The effects of the preparation methods of catatlysts on methane combustionwere studied. The results indicate that La_0.8Sr_0.2CoO₃ catalyst prepared by alaninesolution combustion method has higher catalytic activity for methane combustion,whose T₅₀ and T₁₀₀ were 470℃and 550℃, respectively. It can be explained in termsof the smaller average crystal size, the higher pecific surface are, the lower activationenergy and more mobile chemical-adsorped oxygen in the surface and vacancy. 2. The effects of organic fuels on the structure and the catalytic activities ofLa_0.8Sr_0.2CoO₃ mixed oxides were studied. The results indicate that all La_0.8Sr_0.2CoO₃mixed oxides have large surface area, whose structure and catalytic activities arerelated to the corresponding organic fuels. The catalytic activity of La_0.8Sr_0.2CoO₃catalyst prepared by alanine solution combustion synthesis is the best among allsamples.3. The effects of stoichiometric ratio of organic fuel to oxidizer （φ） on structureand catalytic activities of the catalysts were studied. The results indicate that allLa_0.8Sr_0.2CoO₃ mixed oxides with the different coefficient ofφhave perovskitestructure, whose structure and catalytic activities alter regularly with the changecoefficient ofφ. Whenφis equal to 1.52, the catalytic activity of La_0.8Sr_0.2CoO₃mixed oxides catalyst is the best, whose T₅₀ and T₁₀₀ are respectively 460℃and 540℃, respectively.4. The La_0.8Sr_0.2CoO₃ catalysts of A-site doped different rare earths （Nd,Ce） andB-site doped different transition metals （Ni,Cu） were synthesized by alanine solutioncombustion method. The catalytic activity of La_0.8Sr_0.2CoO₃ mixed oxides for CH₄combustion was studied. The sequences of activities are La_0.8Sr_0.2CoO₃＞Ce_0.8Sr_0.2CoO₃＞Nd_0.8Sr_0.2CoO₃＞La_0.8Sr_0.2Co_0.5Ni_0.5O₃＞La_0.8Sr_0.2Co_0.5Cu_0.5O₃,.5. La_0.8Sr_0.2CoO₃ mixed oxides were prepared by alanine solution combustionmethod and calcined at 600, 700 and 800℃, respectively. The influence of thecalcination temperature of the mixed oxides on the performance of methanecombustion was studied. The catalysts calcined at 700℃has the higher surface area,smaller crystallize, and it has the best activity for methan combustion.更多还原