摘要
采用水油两相双引发剂的无皂乳液聚合法制备了羧基改性的聚甲基丙烯酸甲酯(PMMA)聚合物微球,并以此为模板,采用胶体晶体模板法制备了三维有序大孔(3DOM)钙钛矿LaFeO3催化剂.同时采用柠檬酸络合燃烧法制备了纳米钙钛矿LaFeO3催化剂.通过傅里叶红外光谱、扫描电镜、X射线衍射和激光粒度仪等方法对样品进行了表征.采用程序升温氧化反应评价了催化剂对模拟柴油机炭黑颗粒催化燃烧的活性.结果表明,制备的羧基改性PMMA聚合物微球固含量约为10%,表面羧基含量约为3mmol/g.微球粒径分布均匀,且可通过调节反应条件得到不同的粒径,可控范围在300～700nm.所制得的3DOM钙钛矿LaFeO3催化剂以六方有序的方式排列,其孔径及孔径收缩率分别为300nm和32%,大孔孔壁平均厚度约50nm.该催化剂对炭黑颗粒催化燃烧的T10,T50,T90和SmCO2分别为340,412,458oC和99.8%,性能优于纳米LaFeO3催化剂.
Carboxy-modified polymethyl methacrylate （PMMA） microspheres were prepared using an emulsifier-free emulsion polymerization technique with water-oil biphase double initiators. Three-dimensionally ordered macroporous （3DOM） LaFeO3 perovskite-type complex oxide was synthesized using a colloid crystal template, which was assembled by centrifugation of carboxy-modified PMMA spheres. The nanometric LaFeO3 oxide as a reference sample was also prepared by the citric acid ligation method. The samples were characterized by the techniques of Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and a laser particle size analyzer. Their catalytic performance for diesel soot combustion was investigated by temperature-programmed oxidation reaction. The results indicated that the obtained carboxy-modified PMMA spheres had carboxyl groups on the surface and did not show any aggregation, and they were suitable for the preparation of colloidal crystals. Their contents of solids and carboxyl groups were 10% and 3 mmol/g, respectively. The particle size distribution of the microspheres was narrow and the microspheres with diameter of 300-700 nm can be designed and prepared under different process conditions. The obtained 3DOM LaFeO3 catalyst had a hexagonally well-ordered array, and the diameter of macropore was about 300 nm, corresponding to a shrinkage ratio of 32%. The average thickness of its hole wall was about 50 nm. The T10, T50, and S^mco2 of 3DOM LaFeO3 catalyst for soot combustion were 340, 412, 458℃ and 99.8%, respectively. Compared with the nano-LaFeO3 catalyst for soot combustion, 3DOM LaFeO3 catalyst has higher activity.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2010年第2期236-241,共6页
基金
国家自然科学基金(20833011
20803093和20525621)
高等学校博士学科点专项科研基金(200804251016)
北京市优秀博士论文基金(YB20091141401)
关键词
三维有序大孔材料
钙钛矿氧化物催化剂
胶体晶体模板
柴油机炭黑颗粒
催化燃烧
three-dimensionally ordered macroporous material
perovskite-type oxide catalyst
colloid crystal template
diesel soot
catalytic combustion
