镧元素和氧化铝载体对于铁酸钴催化生长碳纳米管的影响

Effects of lanthanum and alumina support on cobalt ferrite catalyzed growth of carbon nanotubes

关键词:  铁酸钴  碳纳米管  催化剂  化学气相沉积法  自蔓延溶胶凝胶法

Key words:  cobalt ferrite  carbon nanotubes  catalyst  chemical vapor deposition  self-propagating sol-gel method

摘要:

铁酸钴作为碳纳米管催化剂具有较高的催化活性,如何进一步提升铁酸钴催化生长碳纳米管的产率,是碳纳米管宏观制备研究的前沿热点。采用自蔓延溶胶凝胶法制备了铁酸钴催化剂并逐步掺杂硝酸镧、硝酸铝以实现表面修饰改性。针对不同的催化剂设置温度、时间梯度实验,通过化学气相沉积法制备碳纳米管,并采用XRD、SEM、TG等方法对催化剂和碳纳米管进行表征分析。结果表明,镧元素的添加能够降低催化剂的晶粒尺寸,有利于增大催化剂比表面积；氧化铝作为催化剂载体,能够有效增加活性位点,提高分散性,进而提高了催化剂的产率,并使得碳纳米管的平均管径减小。对铁酸钴催化剂的掺杂改性研究为宏量催化制备碳纳米管提供了新的思路和方法,同时为进一步的工艺优化提供了实验依据和理论支撑。

Abstract:

Cobalt ferrite has high catalytic activity as a catalyst for the production of carbon nanotubes. Enhancing the yield of cobalt ferrite catalyzed growth of carbon nanotubes is a cutting-edge research hotspot in the macro-scale preparation of carbon nanotubes. In this paper, a self-propagating sol-gel method was employed to synthesize cobalt ferrite catalyst, followed by sequential doping of lanthanum nitrate and aluminum nitrate to achieve surface modification. Through gradient experiments involving different catalysts with variations in temperature and duration, carbon nanotubes were synthesized via chemical vapor deposition. Characterization of the catalysts and carbon nanotubes was conducted using methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The results indicate that the addition of lanthanum can reduce the grain size of the catalyst and enhance its specific surface area. Alumina, as a catalyst carrier, effectively increases active sites and improves dispersion, leading to an increased yield of the catalyst, and a reduction in the average diameter of carbon nanotubes. The doping modification study of cobalt ferrate catalyst in this paper provides new insights and methods for macro-scale catalytic preparation of carbon nanotubes, while also offering experimental evidence and theoretical support for further process optimization.