NER: Novel Method of Producing Different Carbon Nanostructures in Oxy-Methane Flames Controlled by Electro-Magnetic Fields

NER：在电磁场控制的氧气-甲烷火焰中生产不同碳纳米结构的新方法

• 批准号: 0304528
• 负责人: Lawrence Kennedy
• 金额: $ 9.99万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0304528&HistoricalAwards=false
• 关键词: NER; Novel; Method; Producing; Different

Nanoscale Exploratory Research (NER): Novel Method of Producing Different CarbonNanostructures in Oxy- Methane Flames Controlled by Electro-Magnetic FieldsProject SummaryThis study investigates an adventitious discovery that may lead to an inexpensive means for producing a variety of carbon nanostructures. As part of experiments examining carbon structures in atmospheric oxy-fuel flames, the formation of carbon nanotubes and carbon nanofibers was observed using a nickel-based catalytic support positioned at the fuel side of an oxygen-enriched opposed-flow flame formed by streams of fuel (4% acetylene in methane) and oxidizer (50% oxygen and 50% nitrogen). For constant flame parameters and the same catalytic material, a wide variety of carbon nanostructures were observed and harvested from different positions in the opposed-flow flame. This is the first observation of multiple forms of nanostructures being generated in a single process and selectively harvested. Observed carbon structures include: carbon nanotubes (CNTs) and multi-wall nanotubes (MWNT) bundles, nanofibers with varying degrees of crystallinity, helical regularly coiled tubular carbon nanofibers, ribbon-like coiled nanofibers with rectangular cross section, and, finally, long (~0.2 mm) uniform-diameter (~100 nm) tubular nanofibers exhibiting a regular internal structure of carbon layers. All these variations of carbon nanostructures could be found and harvested in different regions of the fuel side of the opposed-flow oxy-flame. Some of these structures have only recently been synthesized in other laboratories in carefully designed chemical vapor deposition experiments. A key objective of this study is to explore whether the growth and type of nanostructures observed in the earlier studies on an oxy-fuel, counter-flow burner can be controlled using electromagnetic fields, as suggested by preliminary experiments. Potentially, this could result in a new manufacturing process for high-rate production of different nanostructures.Broader ImpactAt present, oxy-flames are the major industrial source of pyrolytic carbon (carbon black). Flames are also widely used for large-scale production of nanoceramics and other nanomaterials. The development of a high-rate synthesis method for carbon nanotubes and carbon nanofibers with controlled structure and morphology makes feasible numerous applications requiring large amounts of carbon nanomaterials. This includes modern composites with unique mechanical and electromagnetic properties, hydrogen storage elements, chemically active materials, fuel additives, etc. Preliminary experimental results showing carbon nanostructures are formed in a catalytic seeded fuel zone of an opposed-flow oxygen-enriched flame and on the application of electromagnetic fields to control the growth rates of carbon nanostructures suggest that manufacturing and harvesting specific types of nanostructures from different regions of a simple opposed-flow combustion facility is feasible and controllable..

纳米尺度探索性研究（NER）：在电磁场控制的氧甲烷火焰中产生不同碳纳米结构的新方法项目摘要这项研究调查了一个偶然的发现，可能导致一种廉价的方法来产生各种碳纳米结构。 作为检验大气氧燃料火焰中的碳结构的实验的一部分，使用位于由燃料流（甲烷中4%乙炔）和氧化剂流（50%氧气和50%氮气）形成的富氧逆流火焰的燃料侧的镍基催化载体来观察碳纳米管和碳纳米纤维的形成。 对于恒定的火焰参数和相同的催化材料，各种各样的碳纳米结构被观察到，并从不同的位置在逆流火焰收获。这是第一次观察到多种形式的纳米结构在一个过程中产生，并有选择地收获。 观察到的碳结构包括：碳纳米管（CNT）和多壁纳米管（MWNT）束、具有不同结晶度的纳米纤维、螺旋状规则盘绕的管状碳纳米纤维、具有矩形横截面的带状盘绕纳米纤维，以及最后，显示出碳层的规则内部结构的长（~ 0.2mm）均匀直径（~100 nm）管状纳米纤维。所有这些变化的碳纳米结构可以被发现和收获在不同区域的燃料侧的对向流氧气火焰。 其中一些结构最近才在其他实验室通过精心设计的化学气相沉积实验合成。 本研究的一个关键目标是探索在早期研究中观察到的氧燃料，逆流燃烧器的纳米结构的生长和类型是否可以使用电磁场控制，如初步实验所示。这可能会导致一种新的制造工艺，用于高速生产不同的纳米结构。更广泛的影响目前，氧气火焰是热解碳（炭黑）的主要工业来源。 火焰也被广泛用于大规模生产纳米铈和其他纳米材料。 具有受控结构和形态的碳纳米管和碳纳米纤维的高速合成方法的开发使得需要大量碳纳米材料的许多应用成为可能。 这包括具有独特机械和电磁性能的现代复合材料、储氢元件、化学活性材料、燃料添加剂，初步实验结果显示，碳纳米结构形成于反向流动氧气-空气混合器的催化晶种燃料区中。富集火焰和应用电磁场控制碳纳米结构的生长速率的研究表明，从简单的逆流燃烧设备的不同区域制备纳米结构是可行的和可控的。