【摘要】：甲烷催化燃燒是一種高效率、低污染的能源利用和廢氣處理技術(shù),能夠通過催化作用降低燃料的起燃溫度和燃燒的峰值溫度,提高甲烷燃燒利用率,減少大氣污染物的生成。鈣鈦礦在氧分離、固體氧化物燃料電池和催化燃燒領(lǐng)域都顯示了其良好的性能,具有替代貴金屬催化劑的潛力。本文制備了La0.6Sr0.4Co0.2Fe00.8O3-δ鈣鈦礦。采用低溫N2物理吸附,X-射線衍射(XRD),氫氣程序升溫還原(H2-TPR),氧氣程序升溫脫附(O2-TPD)和X-射線光電子能譜(XPS)表征了其物理化學(xué)性質(zhì),并考察了低濃度甲烷燃燒催化活性。通過共沉淀法、微乳液法和檸檬酸絡(luò)合法制備了 La0.6Sr0.4Co0.0Fe0.8O3-δ鈣鈦礦催化劑,并研究了制備方法對(duì)催化劑物理化學(xué)性質(zhì)的影響。通過對(duì)比,選擇檸檬酸絡(luò)合法優(yōu)于共沉淀法和微乳液法。采用檸檬酸絡(luò)合法制備La0.6Sr0.4Co0.2Fe0.8O3-δ鈣鈦礦催化劑時(shí),適量的檸檬酸用量會(huì)提高催化劑的氧化還原能力和催化性能。當(dāng)檸檬酸/金屬離子摩爾比為1.25形成的鈣鈦礦晶型更完整,催化劑中的Fe4+和Co3+的還原溫度較低,還原性能好,催化劑表面上吸附氧晶格氧之比最大,低溫還原性最好,催化活性也最好。采用檸檬酸絡(luò)合法制備催化劑時(shí),空氣氣氛和先氮?dú)忸A(yù)處理后空氣焙燒的樣品活性比在氮?dú)鈿夥罩谢钚院?空氣氣氛中檸檬酸自燃放出大量熱量,使得制得的催化劑晶型最好,顆粒最分散,催化劑活性最好。采用檸檬酸絡(luò)合法制備催化劑時(shí),焙燒溫度小于700 ℃時(shí),焙燒溫度略低,鈣鈦礦未完全形成,溫度大于700 ℃時(shí),催化劑團(tuán)聚長(zhǎng)大,并發(fā)生燒結(jié),此時(shí)催化劑粒徑較大。700 ℃焙燒的樣品不僅形成了單一均相的復(fù)合鈣鈦礦氧化物L(fēng)a0.6Sr0.4Co0.2Fe0.8O3-δ催化劑,且該樣品低溫還原性好,化學(xué)穩(wěn)定性較好,對(duì)甲烷的催化燃燒具有較高的催化活性。采用檸檬酸絡(luò)合法制備Ba摻雜的La0.6Sr0.4Co0.2Fe0.8O3-δ鈣鈦礦型催化劑時(shí),鋇摻雜量對(duì)催化劑比表面積影響不大,但會(huì)影響了 B4+含量和表面吸附氧濃度,兩者對(duì)催化活性均有重要影響,在摻雜量為0.1時(shí),反應(yīng)速率達(dá)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，

本文編號(hào)：2490416