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Formation mechanism of fullerenes

富勒烯的形成机理

基本信息

批准号：
11165222
负责人：
OSAWA Eiji
金额：
$ 12.03万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11165222/
关键词：
Mechanism of fullerene formation Natural fullerenes Coal Carbon black C60 TEM Shock wave peaceful use of explosives C_<60>生成機構 3次元螺旋ナノ粒子多層フラーレン煤電子線照射生成自由エネルギー天然カーボンナノチューブ天然カーボンナノ粒子 HPLC

项目摘要

Mechanism of fullerene formation is one of the most difficult problems in fullerene science but has been urgently needed in order to develop industrially favorable synthesis of C60, which is actually a critical obstacle to the emergence of applications of fullerene carbons. During the tenure of this grant, we clarified the mechanism and proposed two entirely new and promising methods of the preparation of C60.Our work is motivated by a novel coal sample arrived from Yunnan Province, China, that contains surprisingly high concentration of C60/C70 (an initial concentration immediately after excavation estimated to be 0.3%). We found three pieces of evidence that indicate that this particular coal has been exposed to shock wave. The strongest evidence is high abundance of the primary particles of soot with extremely small diameter (ca 10 nm in diameters). Noting the fact that the purest and the most readily available soot is commercial carbon black, we thereupon used carbon black in our s … More ubsequent study. Whereas carbon black did not contain measurable amounts of C60, we observed that the primary particles of carbon blacks are cleanly converted to onion-like multi-shell fullerenes upon irradiation with focused electron beam (a substitute of shock wave). Careful examination of this transformation in TEM revealed intervention of spiral particles as the intermediate. Furthermore, we also found that onion changes into spirals. We assumed that the spiral TEM images represent 3D spiroidal particles close in shape with onions. Chemical as well as numerical models were conceived and generated. These works eventually led us to construct a consistent mechanism of fullerene formation consisting of spiral growth of spiroids and the stabilization of spiroid particles into onions by reversible multiple bond cleavage/intershell valence isomerization reactions/multiple bond closure. Success of this mechanism to elucidate the origin of unique configuration of onions encouraged us to conceive a new method of C60 production that uses the production line of carbon black.Another new method of C60 production is simply to expose carbon to shock heating. If shock wave is generated by detonation of explosives and coal is carbon materials, the production of C60 may be carried out on the coal mine site. The method is cost effective, contributes to environmental problem by reducing the CO2 emission by burning coal as the fuel, and also promotes the use of explosives for peaceful purposes. There are already some examples previously reported in the literature that indicates that somewhat shock wave will generate fullerenes in stead of diamond under some conditions. For example, in a shock tube experiment, 300 ppm of C60 was formed when benzene was subjected to detonative shock. A few careful preliminary experiments will be needed to verify the present proposal. Less

富勒烯形成机理是富勒烯科学中最困难的问题之一，但为了开发工业上有利的C60合成方法，迫切需要解决这一问题，这实际上是富勒烯碳应用出现的关键障碍。在这笔资助期间，我们阐明了该机制，并提出了两种全新且有前景的 C60 制备方法。我们的工作受到来自中国云南省的一种新型煤样的推动，该煤样含有令人惊讶的高浓度 C60/C70（挖掘后的初始浓度估计为 0.3%）。我们发现了三项证据，表明这种特殊的煤炭已经受到冲击波的影响。最有力的证据是具有极小直径（直径约 10 nm）的烟灰初级颗粒的大量存在。注意到最纯净、最容易获得的烟灰是商业炭黑这一事实，我们因此在后续研究中使用了炭黑。尽管炭黑不含可测量量的 C60，但我们观察到，在聚焦电子束（冲击波的替代品）照射下，炭黑的初级颗粒完全转化为洋葱状多壳富勒烯。在 TEM 中仔细检查这种转变揭示了螺旋粒子作为中间体的干预。此外，我们还发现洋葱变成螺旋状。我们假设螺旋 TEM 图像代表与洋葱形状接近的 3D 螺旋颗粒。构思并生成了化学模型和数值模型。这些工作最终使我们构建了富勒烯形成的一致机制，包括螺旋体的螺旋生长和通过可逆的多键断裂/壳间价异构化反应/多键闭合将螺体颗粒稳定成洋葱。这一机制的成功阐明了洋葱独特结构的起源，这促使我们构思一种使用炭黑生产线生产 C60 的新方法。 C60 生产的另一种新方法是将碳暴露于骤热。如果炸药爆炸产生冲击波，而煤是碳材料，则C60的生产可以在煤矿现场进行。该方法具有成本效益，通过燃烧煤炭作为燃料来减少二氧化碳排放，有助于解决环境问题，并且还促进了爆炸物的和平用途。文献中已经有一些先前报道的例子表明，在某些条件下，一定程度的冲击波会生成富勒烯而不是金刚石。例如，在激波管实验中，当苯受到爆炸冲击时，形成了 300 ppm 的 C60。需要进行一些仔细的初步实验来验证当前的提议。较少的