摘要
以La2O3和Mn(NO3)2为原料,用"溶胶 凝胶"法结合"超临界干燥技术"制备镧锰气凝胶,在600,800℃下煅烧镧锰气凝胶,制备超细钙钛矿型LaMnO3+λ,用XRD,TEM,DTA,TG等手段对样品进行表征;并分别用CH4和CO气体的氧化反应来检测LaMnO3+λ的催化活性。结果显示:(1)制得镧锰气凝胶为疏松、具有较好分散性的棕色粉末;其中镧以氢氧化镧形式存在,而锰以非晶态形式存在;(2)镧锰气凝胶由针柱状晶体和散落在四周的絮状物组成,针柱状晶体的长度约为几个微米,粗端宽度约为100nm,细端宽度30nm;而絮状物尺寸范围跨度较大,大片絮状物尺寸范围约为500nm×150nm,小颗粒的直径仅为几个纳米;(3)镧锰气凝胶600℃下煅烧得LaMnO3,800℃下得LaM nO3.15;(4)超细钙钛矿型LaMnO3+λ气体净化催化剂对CH4和CO气体具有较好的催化活性。
Using La_2O_3 and Mn(NO_3)_2 as raw materials, the ultrafine lanthanum-manganese aerogel was prepared by sol-gel and surpercritical fluid drying complex technology. Calcining lanthanum-manganese aerogel at 600 and 800 ℃. The samples were characterized by FT-IR, XRD, TEM techniques and thermo-gravimetric, differential thermal analysis, and using CH_4, CO oxidized reaction to inspect the catalytic activity of LaMnO_(3+λ). The result shows that (1) The method can get brown-blue, well-dispersed ultrafine powder, the existing form of lanthanum is La(OH)_3 crystaline, and the existing form of manganese is amorphous condition. (2) It is composed of needle-column particles and wadding form particles distributed surrounding. The length of needle-column particle is about a few micrometers. The width of column end is about 100 nm, and the wide of needle end is about 30 nm. The range of the size of wadding form is great. The big wadding form particle is about 500 nm×150 nm, and the diameter of small particle is about a few nanometer. (3) Ultrafine LaMnO_3 can be got at 600 ℃ by calcining lanthanum-manganese aerogel, ultrafine LaMnO_(3.15) can be got at 800 ℃. (4) Nanometer perovskite oxide LaMnO_(3+λ) catalytic activity is fair for CO, CH_4 oxidation.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2005年第1期113-117,共5页
Journal of the Chinese Society of Rare Earths
基金
湖北省教育厅重点科研资助项目(2002A01018)
湖北省优秀中青年人才科研计划项目(2002B011004)
关键词
LaMnO3+λ
气凝胶
超临界干燥
热分析
稀土
LaMnO_(3+λ)
aerogel
surpercritical fluid drying
thermo gravimetric analysis
rare earths
