柠檬酸/金属离子比对La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)钙钛矿的制备及性能的影响  

Influence of citric acid to metal ions molar ratio upon preparation and performance of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) perovskites

作　　者：蔡静文 王琪 陈亚中 崔鹏 CAI Jingwen;WANG Qi;CHEN Yazhong;CUI Peng(School of Chemistry and Chemical Engineering,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]合肥工业大学化学与化工学院,安徽合肥230009

出　　处：《合肥工业大学学报（自然科学版）》2018年第8期1112-1117,共6页Journal of Hefei University of Technology：Natural Science

基　　金：国家自然科学基金资助项目(21106027)

摘　　要：文章采用柠檬酸络合法制备了La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)钙钛矿,采用低温N_2物理吸附、X-射线衍射(X-ray diffraction,XRD)、氢气程序升温还原(hydrogen temperature programmed reduction,H_2-TPR)、氧气程序升温脱附(oxygen temperature programmed desorption,O_2-TPD)和X-射线光电子能谱(X-ray photoelectron spectroscopy,XPS)表征了其物理化学性质,并考察了甲烷催化燃烧活性。结果表明,当柠檬酸/金属离子摩尔比(citric acid to metal ions molar ratio,CMMR)为1.25时,所制得的催化剂催化活性最佳。XRD表征结果表明,CMMR为1.25或1.50时,形成的钙钛矿晶型更完整。H_2-TPR表征结果表明,CMMR为1.25时,催化剂中的Fe^(4+)和Co^(3+)的还原温度较低,还原性能好。XPS表征结果表明,CMMR为1.25时,催化剂表面上吸附氧晶格氧之比最大。O_2-TPD表征结果表明,随着CMMR增加,催化剂中可移动晶格氧量减小,脱附温度增加,非化学计量比显著减小。CMMR为1.25时,催化剂表面吸附氧较易活化,形成活性物种。La0.6Sr0.4Co0.2Fe0.8O3-δperovskite samples were prepared through citric acid complexing method.The catalysts were characterized with low temperature N2 absorption,X-ray diffraction(XRD),hydrogen temperature programmed reduction(H2-TPR),oxygen temperature programmed desorption(O2-TPD)and X-ray photoelectron spectroscopy(XPS).And their catalytic performance for methane combustion was investigated.The results indicated that perovskite with a citric acid to metal ions molar ratio(CMMR)of 1.25 exhibited the best catalytic performance.XRD characterization confirmed that CMMR of 1.25 or 1.50 benefited the formation of perovskite structure with less impurity.H2-TPR characterizations confirmed that CMMR of 1.25 corresponded to lower reduction temperatures for Fe^4+and Co^3+.XPS results indicated that the ratio between adsorbed oxygen species and lattice oxygen was the highest when CMMR was 1.25.O2-TPD results also confirmed the higher lattice oxygen mobility for the sample with CMMR of 1.25.Catalyst with a CMMR of 1.25 adsorbed oxygen more easily,forming active species.

关 键 词：柠檬酸 La0.6Sr0.4Co0.2Fe0.8O3-δ 钙钛矿 甲烷燃烧 催化性能 

分 类 号：TQ032.41[化学工程]