聚合—热解法制备沥青基炭微球的研究

发布时间：2018-05-09 19:26

本文选题：MCMB + 甲醛　；参考：《福州大学》2010年硕士论文

【摘要】：本文研究了在酸性催化剂的条件下采用甲醛对煤沥青进行聚合改性，然后对改性沥青进行热解制备出中间相炭微球（MCMB）。研究了改性煤沥青的中间相转化行为，探索了MCMB的制备工艺与结构和性能之间的关系。以MCMB为原料，对MCMB进行热处理，将处理过的炭微球应用于锂离子电池的负极材料，并分析了MCMB的结构和粒径分布与电化学性能之间的关系。采用FT-IR、1H-NMR、XRD、TG和流变仪对改性煤沥青的结构和性能进行了分析。结果表明：甲醛在草酸的作用下与煤沥青中的多环芳烃发生亲电取代反应，进一步的环化和芳构化，形成分子量大的多核芳烃化合物。改性后煤沥青的残炭率和软化点都有了明显的提高，同时它的耐热性和流变性能都有了很大的改善，表现出非牛顿流体行为的性质，并且改性后煤沥青的粘流活化能降低，表现出对温度的不敏感性。采用FT-IR、SEM、TEM和偏光显微镜对中间相转化过程中的结构和形貌进行了观察。研究表明：在炭化过程中，C-H、C-C键断裂形成具有自由活性的自由基，随着温度的升高，，分子结构发生重排，进一步稠化、脱氢缩聚反应，形成分子量更大的平面稠环芳烃化合物，在表面张力的作用下，形成MCMB。采用SEM、XRD、粒度分析仪等分析手段，研究了MCMB的制备工艺、组成与性能的关系。结果表明：不同的工艺条件对于MCMB的结构和性能均有不同程度的影响，特别是炭化温度和保温时间的影响更为显著，在460℃下炭化保温2h，MCMB的收率达到30.23%，并且球形度好，粒径分布均匀；炭黑在炭微球的形成过程中起到了成核的作用，并且阻止了炭微球的融并，使MCMB粒径分布更均匀。通过电化学性能测试考察了MCMB作为锂离子电池负极材料的性能，研究了热处理温度以及粒径对其电化学性能及循环性能的影响。研究表明：MCMB的可逆容量和不可逆容量，都随着热处理温度的升高而降低，而库仑效率升高；同时电化学性能随粒径的变化而表现出一定的规律。随着平均粒径的增大，可逆容量和不可逆容量逐渐减小，库仑效率则升高。将1000℃热处理的炭微球制成锂离子负极材料，经过30次充放电循环后，容量下降仅为6.5%。
[Abstract]:This paper studied the polymerization modification of coal tar pitch with formaldehyde under the condition of acid catalyst. Then the mesophase microsphere (MCMB) was prepared by pyrolysis of modified bitumen. The intermediate phase transformation behavior of modified coal tar pitch was studied. The relationship between the preparation process of MCMB and the structure and energy of the asphalt was explored. The MCMB was used as the raw material to heat the MCMB. The treated carbon microspheres were applied to the anode materials of lithium ion batteries, and the relationship between the structure and particle size distribution of MCMB and the electrochemical performance was analyzed.
The structure and performance of modified coal tar pitch were analyzed by FT-IR, 1H-NMR, XRD, TG and rheometer. The results showed that formaldehyde was electrophilic substitution reaction with polycyclic aromatic hydrocarbons in coal tar pitch under the action of oxalic acid, further cyclization and aromatization, and formed a polyarene compound with large molecular weight. The residual carbon rate and softening of modified coal bitumen. At the same time, the heat resistance and rheological properties have been greatly improved, and the properties of non Newton fluid behavior are shown, and the viscous flow activation energy of the modified coal bitumen is reduced and the temperature is insensitive to the modified coal tar.
The structure and morphology of the mesophase transformation were observed by FT-IR, SEM, TEM and polarizing microscope. The results showed that in the carbonization process, the free radicals were formed with the free activity of C-H and C-C bonds. With the increase of temperature, the molecular structure rearranged, further thickened, dehydrogenized and condensed, and formed a larger molecular weight plane. Polycyclic aromatic hydrocarbons form MCMB. under the action of surface tension.
By means of SEM, XRD and particle size analyzer, the relationship between the preparation process and the composition of MCMB is studied. The results show that the different technological conditions have different influence on the structure and properties of MCMB, especially the influence of carbonization temperature and holding time, and the heat preservation of 2H at 460 C and the yield of MCMB is 30.2. 3%, the sphericity is good and the particle size distribution is uniform. Carbon black plays a nucleation role in the formation of carbon microspheres, and prevents the melting of carbon microspheres, so that the distribution of MCMB particle size is even more uniform.
The performance of MCMB as a anode material for lithium ion batteries was investigated by electrochemical performance test. The effects of heat treatment temperature and particle size on its electrochemical performance and cyclic properties were investigated. The results showed that the reversible capacity and irreversible capacity of MCMB decreased with the increase of heat treatment temperature, and the coulomb efficiency increased; With the increase of the average particle size, the reversible capacity and irreversible capacity gradually decrease with the increase of the average particle size, and the coulomb efficiency increases. The carbon microspheres treated at 1000 C are made of lithium ion anode material. After 30 charging and discharging cycles, the capacity drop is only 6.5%.

【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TQ522.65

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