碳/氧化物复合物中碳层对氧化物相变的影响  

Influence of Carbon on Phase Transformation of Oxides in Carbon/Oxide Composites

作　　者：郭颖[1] 王培[2] 隗罡[1] 王羽[1] 朱月香[1] 谢有畅[1] 

机构地区：[1]北京大学化学与分子工程学院、分子动态与稳态结构国家重点实验室、北京分子科学国家实验室,北京100871 [2]中国工程物理研究院、化工材料研究所,四川绵阳621900

出　　处：《物理化学学报》2010年第7期1887-1892,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20973012);国家重点基础研究发展规划项目(973)(2006CB806100)资助~~

摘　　要：碳/氧化铝(氧化钛)复合物具有独特的物理化学性质,在吸附和催化过程中有广泛应用.复合物中碳层对氧化物的相变有重要影响.在高温下通氧气焙烧碳/γ-Al2O3复合物可使γ-Al2O3迅速转变为α-Al2O3;而在惰性气氛中,碳层可显著抑制氧化铝的相变与烧结.碳/氧化钛体系中,碳层可明显提高氧化钛在惰性气氛中的热稳定性,在800℃以下碳层能有效阻止锐钛矿相向金红石相的转变;在含氧气氛中控制焙烧条件可将碳层完全除去而基本不影响氧化钛的物相组成及织构.因此,碳层可作为一种特殊的表面修饰剂,既可在高温下抑制氧化物的相变,又可避免在氧化物中引入掺杂元素.Carbon/alumina （titania） composites have unique physicochemical properties and have been widely used in adsorption and catalysis.Carbon in these composites greatly influences the sintering and phase transformation behavior of the oxides.Calcining carbon/γ-Al2O3 in oxygen at high temperature results in a quick γ-to α-Al2O3 transformation.In nitrogen, X-ray diffraction （XRD） analysis showed that carbon inhibited the phase transformation significantly.This inhibition effect was found to be carbon content dependent.For the carbon/titania system, pure titania and carbon-protected-titania samples were calcined at different temperatures and analyzed by XRD, transmission electron microscopy （TEM）, and Raman spectroscopy.Surface area and pore size analysis was performed by isothermal nitrogen adsorption-desorption.Results show that the carbon layer can improve the thermal stability of the TiO2 nanoparticles and hinder the phase transformation of anatase to rutile at up to 800 ℃ under nitrogen-protected heat treatment.On the other hand, carbon can be removed by controlling calcination in oxygen at 500 ℃ without affecting the phase composition and texture of titania.The carbon removal efficiency was examined by temperature-programmed oxidation （TPO） analysis.Therefore, carbon can be used as a special surface modifier which can inhibit the high temperature phase transformation of oxides without introducing alien elements effectively.

关 键 词：碳 氧化铝 氧化钛 相变 锐钛矿 金红石 

分 类 号：O643.36[理学—物理化学]