超临界流体干燥技术制备Nd_xO_y气凝胶

Preparation of Nd_xO_y Aerogel by Supercritical Fluid Drying Technique

以化学纯Nd2(CO3)3.6H2O为主要原料,用溶胶-凝胶法结合超临界流体干燥技术制备钕气凝胶,经850℃煅烧制备纳米NdxOy微粉。采用XRD、TEM、FT-IR对样品进行表征,重点考察制备工艺对NdxOy气凝胶晶态、形貌和尺寸的影响,并通过“CO+NO”的反应测试其催化活性。结果显示:(1)溶胶-凝胶法结合超临界流体干燥技术可制备出疏松、分散性较好的灰褐色的钕气凝胶;(2)260℃时,NdxOy气凝胶呈枝状,其宽度介于10nm^30nm,长度介于200nm^350nm;经850℃煅烧,NdxOy微粉由Nd2O3和NdO2组成,形貌仍呈枝状,且长度明显减小;(3)超临界流体干燥技术有效地解决了纳米NdxOy微粉制备过程中的“团聚”问题;(4)单一纳米NdxOy微粉对“NO+CO”反应的催化净化效果不明显。

Using Nd2 （CO3）3 · 6H2O as the main material, the aerogel of neodymium was prepared by sol-gel method combined with super-critical fluid drying technique, and it was calcined at 850℃, then nanometer micropowder of NdxOy could be gained. The sample was characterized by XRD,TEM,FT-IR. The key aim was to consider the effect of super-critical fluid drying technique and calcinations technique on crystal shape, appearance and size, then through the chemical reaction ＂CO＋ NO＂ to check the catalytic activity and to discuss its use in catalysis of purification of automobile exhaust. The result shows as follows ： （1） The prepared neodymium aerogel was a kind of taupe well-dispersed loosen powder; （2） At 260℃ ,the forerunner body of NdxOy aerogel was made up of some dendritic substance. The width of the substance was about between 10nm and 30nm and the length was about between 200nm and 500nm. After calcined at 850℃, calcinate was made up of Nd203 and NdO2, NdxOy remains arborization. The width of substance was still about between 10nm and 30nm but the length was serious reduced to 50nm to 500nm. ; （3）Super-critical fluid drying technique effectively solved the conglobation problem when nanometer micropowder of NdxOy is prepared ; （4）The catalytic effect of nanometer NdxOy is not obvious for the reaction ＂NO＋ CO＂.