The influence of carbon source and catalyst nanoparticles on CVD synthesis of CNT aerogel
The influence of carbon source and catalyst nanoparticles on CVD synthesis of CNT aerogel
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DOI：
10.1016/j.cej.2016.11.157
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发表时间：
2017-04-15
影响因子：
15.1
通讯作者：
Boies, Adam
中科院分区：
文献类型：
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作者：
Hoecker, Christian;Smail, Fiona;Boies, Adam
浮动催化剂化学气相沉积 (FC-CVD) 方法的独特之处在于，能够通过一步连续气相工艺在工业规模上连续合成碳纳米管 (CNT)。控制铁基催化剂纳米粒子的形成被广泛认为是优化碳纳米管产品性能和生产率的主要参数。在此，热解碳物质和催化纳米颗粒的综合影响均显示出影响碳纳米管气凝胶的形成。这项工作研究了形成的碳纳米管中碳的来源、气凝胶形成的位置、催化剂纳米颗粒的原位行为以及所得碳纳米管的相关形态。使用同位素标记的甲烷 (CH4) 进行的轴向测量表明，所有 CNT 内的碳主要源自 CH4，而不是一些早期形成的 CNT 主要通过催化前体组分的热分解提供碳。沿反应器轴线对 CNT 产量的量化明确消除了注入参数影响 CNT 形成的观点，而是表明无论碳源（CH4、甲苯或乙醇）如何，大量 CNT 形成都发生在反应器出口附近。向不同反应器位置供应碳表明，只要碳源达到足够的温度（>1000摄氏度）以引发热解，即使碳被输送到反应器出口附近，也会发生CNT气凝胶形成。这些结果表明了如何通过修改下游催化剂和碳输送来优化和控制未来的大规模碳纳米管反应器。 (C) 2016 Elsevier B.V. 保留所有权利。
The floating catalyst chemical vapor deposition (FC-CVD) method is unique in providing the capability for continuous carbon nanotube (CNT) synthesis at an industrial scale from a one-step continuous gas-phase process. Controlling the formation of the iron-based catalyst nanoparticles is widely recognized as a primary parameter in optimizing both CNT product properties and production rate. Herein the combined influences of pyrolytic carbon species and catalytic nanoparticles are both shown to influence CNT aerogel formation. This work studies the source of carbon in the formed CNTs, the location of aerogel formation, the in-situ behaviour of catalyst nanoparticles and the correlated morphology of the resultant CNTs. Axial measurements using isotopically-labelled methane (CH4) demonstrate that carbon within all CNTs is primarily derived from CH4 rather than some of the early-forming CNTs being predominantly supplied with carbon via thermal decomposition of catalytic precursor components. Quantification of CNT production along the axis of the reactor definitively dispels the notion that injection parameters influence CNT formation and instead shows that bulk CNT formation occurs near the reactor exit regardless of the carbon source (CH4, toltiene or ethanol). Supply of carbon to different reactor locations indicates that CNT aerogel formation will occur even when carbon is delivered near the exit of the reactor so long as the carbon source reaches a sufficient temperature (>1000 degrees C) to induce pyrolysis. These results give an indication of how future large-scale CNT reactors may be optimized and controlled by modifying downstream catalyst and carbon delivery. (C) 2016 Elsevier B.V. All rights reserved.