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脱油沥青基碳材料的溶剂热合成和铁磁性研究

Study on Solvothermal Synthesis and Ferromagnetic Properties of Carbon Materials from DOA

【作者】 文海荣

【导师】 刘旭光;

【作者基本信息】 太原理工大学 , 应用化学, 2009, 硕士

【摘要】 碳包覆纳米金属颗粒(CEMNPs)、碳纳米管(CNTs)、纳米洋葱状富勒烯(NOLFs)、碳纳米纤维(CNFs)、碳微球(CMSs)和碳纳米棒(CNRs)等多种形貌的新型碳功能材料以其特殊的结构赋予了其优异的性能和广阔的应用空间。脱油沥青(DOA)是重油加工过程中的副产物,作为一种富碳的复杂混合物,可进行合成碳材料的研究。从DOA中获得高附加值产品,可为扩展传统石油加工过程的产品链并实现资源的综合利用提供新的途径。本文主要以DOA为原料,采用溶剂热合成法,甲苯为反应溶剂,二茂铁为催化剂,通过改变两性共聚物P123(P123)的加入量,合成了不同形貌的碳材料。采用场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)、X-射线衍射(XRD)、红外光谱(FT-IR)等对产物进行了表征和分析,并利用振动样品磁强计(VSM)测试了产物的铁磁性能。结果表明:1、以0.3g DOA为原料,40mL甲苯为反应溶剂,二茂铁为催化剂前躯体,0.8g P123为表面活性剂,溶剂热合成法制备了CEMNPs。考察了反应温度、反应时间、催化剂二茂铁含量和反应气氛对产物的影响:温度450℃,时间4h,二茂铁含量10wt.%,氮气气氛下合成了粒径均匀的CEMNPs,其直径分布在100-300nm,内包核为Fe3O4,外壳层为无定形碳层。FT-IR表征显示产物表面含有碳氢类基团。通过考察不同反应物组配对产物的影响,初步探讨了溶剂热合成CEMNPs的生长机理:产物是在二茂铁的催化作用及P123对DOA芳族分子的组装作用下形成的。铁磁性测试表明:所制备CEMNPs的矫顽力为160Oe,呈明显的铁磁性。2、以0.3g DOA为原料,40mL甲苯为反应溶剂,含量10wt.%的二茂铁为催化剂前躯体,氮气气氛下450℃反应4h,当P123的加入量为3.5g时,制备了一种新颖结构、分布均匀的蠕虫状碳材料,其直径约0.5μm,长约1-1.5μm。FT-IR表征显示产物表面含有碳氢类基团。初步探讨了其生成机理:二茂铁的催化作用及P123对DOA芳族分子的分散组装作用决定了蠕虫状碳材料的形成。铁磁性能测试表明:所制备蠕虫状碳材料的矫顽力为231Oe,也呈明显的铁磁性。3、当40mL甲苯中加入0.3g二茂铁时,氮气气氛下450℃溶剂热4h生成了副产物相互缠绕的CNFs,直径约100nm,产物中还发现有螺旋状CNFs。

【Abstract】 Advanced carbon functional materials, such as cabon-encapsulated metal nanoparticle (CEMNP), carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon microspheres (CMSs) and carbon nanorods (CNRs), have excellent properties and potential applications because of their special structure. Deoiled asphalt (DOA) is a carbon-rich by-product of petroleum industry, which can be used to synthesize various carbon structures. Utilization of DOA can provide a new approach for expansion of product chains of petroleum processing and comprehensive utilization of petroleum resource.In this paper, carbon materials with different morphologies were achieved from DOA by solvothermal synthesis. Field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were employed to characterize the morphology and structure of the products. The ferromagnetic property of the products was measured with a vibrating sample magnetometer (VSM). The results are as follows:1. CEMNPs were synthesized by solvothermal synthesis route using DOA as carbon precursor, amphiphilic triblock copolymer P123 (P123) as surfactant and ferrocene as catalyst. The influences of different experimental parameters, such as reaction temperature, reaction time, ferrocene content and reaction atmosphere, were investigated, with respect to the morphologies of the products. CEMNPs were obtained with Fe3O4-amorphous carbon layer core-shell structure and uniform diameters of about 100-300nm using ferrocene content of 10wt.% at 450℃for 4h in N2 atmosphere. In addition, hydrogen-carbon bondings were observed on surface of CEMNPs. The discussion of growth mechanism indicates that the catalysis of ferrocene and the assemblies of the aromatic molecules of DOA directed by P123 were crucial to the formation of CEMNPs. The coercivity value (160Oe) from measurement of VSM showed an obvious ferromagnetic behavior.2. A novel worm-like carbon structure was obtained at 450℃for 4h in 40mL of toluene solution through a solvothermal synthesis route under N2 atmosphere, using 0.3g of DOA, 3.5g of P123 and 10wt.% of ferrocene. The obtained products had good dispersion and uniform diameters of about 0.5μm and lengthes of 1-1.5μm. In addition, hydrogen-carbon bondings were observed on surface of worm-like carbon structures. The discussion of growth mechanism indicates that the catalysis of ferrocene and the dispersities and assemblies of the aromatic molecules of DOA directed by P123 were critical for the formation of the samples. The coercivity value (231Oe) from the measurement of VSM also showed an obvious ferromagnetic behavior.3. CNFs were synthesized using 40mL of toluene as the solvent and ferrocene as carbon source and catalyst precursor at 450℃for 4h under N2 atmosphere,which were inter twisted with diameters of 100nm. In addition, some helical CNFs were also observed.

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