Pérez-Cabero M, Taboada J B, Guerrero-Ruiz A, Overweg A R, Rodríguez-Ramos I
Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, Cantoblanco, 28049, Madrid, Spain.
Phys Chem Chem Phys. 2006 Mar 14;8(10):1230-5. doi: 10.1039/b516243b. Epub 2006 Feb 6.
57Fe Mössbauer spectroscopy was used to study the reduction behavior at temperatures as high as 1073 K of an iron/silica catalyst, and also the carbonaceous materials isolated after acetylene decomposition over this catalyst at several temperatures (873-1073 K). The products were previously characterized by transmission electron microscopy and it was clearly proven that the concentration of carbon nanotubes increased when reaction reached highest temperatures. This was related with an increment in cementite concentration (generated from initial alpha-iron and the progressive reduction of the remnant Fe+2 caused by acetylene decomposition) as detected by 57Fe Mössbauer. These results undoubtedly revealed the role of alpha-iron as active center for acetylene decomposition and cementite as main carbide intermediate species in the catalytic growth of CNTs.
采用57Fe穆斯堡尔光谱研究了铁/二氧化硅催化剂在高达1073 K温度下的还原行为，以及在几个温度（873 - 1073 K）下乙炔在该催化剂上分解后分离出的含碳物质。产物先前已通过透射电子显微镜进行了表征，并且清楚地证明，当反应达到最高温度时，碳纳米管的浓度增加。这与通过57Fe穆斯堡尔检测到的渗碳体浓度增加有关（由初始α-铁以及乙炔分解导致的残余Fe+2的逐步还原产生）。这些结果无疑揭示了α-铁作为乙炔分解活性中心的作用，以及渗碳体作为碳纳米管催化生长中主要碳化物中间物种的作用。
