【作者】 赵雪飞；

【导师】 邱介山；

【作者基本信息】 大连理工大学 ， 化学工艺， 2011， 博士

【摘要】 以富勒烯、碳纳米管和石墨烯为家族成员的碳纳米材料是近年来纳米科技发展的一面旗帜,是众多科学家竞相研究的热点。随着研究工作的不断深入,从理论探讨到制备工艺开发都取得了一系列重大的突破。而碳纳米材料低成本规模化可控制备、生长机制至今仍然是限制其工业化应用的主要瓶颈。本论文工作以不同组成和结构特征的碳源为前驱体,系统研究了富勒烯和碳纳米管的可控制备和分离提纯,并对碳原子数60以下的低碳富勒烯加氢、卤化生成机制进行了理论研究。主要研究结果如下：(1)优化电弧放电工况条件及固体碳源组成和结构,成功获得了高产率的富勒烯。采用12脉冲可控硅整流电源减小整流电压波动,改善直流放电质量和放电电弧平稳性,粗富勒烯收率明显优于6脉冲整流放电之结果；无烟煤、针状焦、石墨、膨胀石墨均是合成富勒烯的合适原料,其中以膨胀石墨为碳源,富勒烯产率最高,表明前驱体的结构与富勒烯产率之间有内在的关联。(2)将模拟移动床色谱分离技术应用于粗富勒烯的分离提纯,获得了高纯度/高提取率的富勒烯。以粒径20μm-30μm、孔径12nm的球形ODS为固定相,一定比例的甲苯、甲醇混合溶剂为淋洗液,在模拟移动床色谱分离系统上可实现C60、C70与其他杂质的高效分离,从而获得高纯度、高产率的产品,其中C60纯度大于98%,提取率95.7%,C70的纯度大于98%,提取率达到98%。(3)以煤、针状焦为碳源,可控制备得到了多种不同形貌和结构特征的碳纳米材料。采用直流电弧放电技术,在0.020MPa氦气气氛下,以白杨树煤(无烟煤)为原料,制备得到了大量管径50nm左右的开口竹节状碳纳米管和以绒毛球状组装结构存在的直径20nm-30nm的碳纳米纤维；以高度光学各向异性的针状焦为碳源,铁粉为催化剂,直流电弧放电获得了表面修饰铁纳米粒子(5nm-10nm)、长度达微米尺度、直径20nm-50nm的一维碳纳米棒结构；以针状焦为碳源,FeCl3作为催化剂前躯体,通过直流电弧放电制备出了高质量和高产率的双壁碳纳米管,表明针状焦是制备双壁碳纳米管的理想原料。(4)利用密度泛函理论开展了富勒烯与H、F、Cl原子相互作用机理研究,为研究碳纳米材料的微观形成机制提供了有价值的信息。通过势能面分析和异构体之间转化活化能计算,对C28(Td)、C40(Td)的氢化与卤化机制进行了理论预测,发现C28(Td)、C40(Td)更容易与X(X=H、F、Cl)原子发生反应,生成更加稳定的C28(Td)X4和C40(Td)X4化合物。对C28(Td)X、C40(Td)X各自异构体相互转化的研究表明,它们之间的反应都是一步反应,由于反应通道的能垒较高,在室温下它们之间的相互转化难以实现。更多还原

【Abstract】 Nanocarbon materials including fullerenes, carbon nanotubes and graphene, have become the hot topics in recent years and play a leading role in the nanoscience and nanotechnology. Many breakthroughs have been accomplished both in the synthesis technique and theoretical research. However, the insolubilities of controllable fabrication in large-scale and growth mechanism still act as the main bottle-necks and limitations to their application widely in industry world. This work in the dissertation used various starting materials with different structures and compositions and investigated the controllable preparation, separation and purification of fullerene and carbon nanotubes based materials, meanwhile the mechanisms of hydrogenation and halogenation of the fullerenes with less carbon atoms than 60 have been studied theoretically.The main results are summarized as following:(1) By means of optimizing the operating conditions, the compositions and structures of the solid carbon starting materials, high yields of fullerene have been achieved in the process of arc discharge. Silicon-controlled rectifier with twelve-pulses has been used to minimize the fluctuation of direct-current (DC) wave for the stabilization of the arc discharge. Higher yield of fullerenes has been accomplished compared with that in the case of six-pulses. Anthracite, needle-coke, exfoliated graphite as well as graphite can be used as the starting materials for the production of fullerenes in the arc discharge, and the exfoliated graphite give rise to the highest yield of fullerene. Therefore, this suggests that there is an inherent relationship between the yield of fullerenes and structures of carbon precursors.(2) High purity of fullerene has been achieved by means of simulated moving bed (SMB) chromatography technology from the raw fullerenes obtained by arc discharge. Ball-like ODS with diameter of 20-30μm and pore size of 12nm is used as the stationary phase and the mixture of methanol and toluene as the eluent for the separation of fullerene. High purity (98% for both C60 and C70) and high extraction yield (95.7%,98% for C60 and C70, respectively) have been obtained. This demonstrates that the SMB chromatography technology is a high efficient approach to the purification of fullerenes.(3) Coal and needle-coke are used as the carbon source for the production of carbon nano-materials with various morphologies. With Baiyangshu coal (anthracite) as starting materials and He (0.020MPa) as discharge atmosphere, bamboo-like carbon nanotubes with diameter of 20-30nm and open end, as well as fluffy ball-like assemblies composed of carbon nanofibers with diameter of 20-30nm are grown in large-scale. Needle-coke with high optical anisotropy is used as carbon source and iron powder as catalyst, nanorods decorated with Fe nanoparticles (5-10 nm) on the surface and length of micrometer size are obtained with arc discharge method; While double-walled carbon nanotubes with high yield and high quality rather than Fe decorated nanorods are prepared with FeCl3 replacing of Fe powder as the catalyst precursor. This indicates that the needle-coke is the appropriate precursor for the production of double-walled carbon nanotubes.(4) Density functional theory is used to predict the fullerenes interacted with H, F and Cl atom for the purpose of pursuing valuable information for the growth mechanism of nanocarbon materials. Through the analysis of the potential energy surface and calculation of activation energy for the conversion between different isomers, the hydrogenation and halogenation mechanism of C2s(Td), C40(Td) are predicted with this theory. It demonstrates that the reaction between C28(Td), C4o(Td) and X(X=H,F,Cl) is easy and give rise to stable compounds of C2s(Td)X4 and C4o(Td)X4, respectively. It is shown that the conversion between isomers of C28(Td)X, C40(Td)X is a one step reaction, which become impossible at the room temperature because of the high energy barrier in the reaction channel.更多还原