机械振动对改性煤沥青制备针状焦结构影响的研究

发布时间：2018-02-24 06:02

  本文关键词： 煤沥青 改性 机械振动 中间相 半焦 针状焦　出处：《太原理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：针状焦是一种结构非常有序、性能优良的一种焦炭。因其具有热膨胀系数小、机械强度高、导电率高、耗能低和易石墨化等优点，工业上常用做制备高功率(HP)和超高功率(UHP)石墨电极的原料。然而我国生产的针状焦与发达国家生产的相比，存在体积密度大、电阻率高等缺陷。目前，我国的针状焦仍以进口为主，严重制约了我国电炉炼钢产业的发展。所以，如何制备高质量的针状焦对于我国“富煤贫油少气”而大力发展的煤化工产业有着十分积极的意义。 本实验研究了中温煤沥青经过G和D改性后，其喹啉不溶物含量、β树脂含量、软化点、结焦值等理化性质的变化，，分析了不同质量比下制得的改性煤沥青（MCTP）的性质差异。发现与未改性的RCTP相比，MCTP的TI含量、β树脂含量、SP和CV都呈现出先增加后降低的趋势，QI含量随改性剂含量的增加而增多。 对MCTP做了氢核磁和元素分析，结果发现改性后MCTP的H含量增加、C含量减少，相应的H/C比值也增加；改性后芳香氢所占比例增大。改性促使稠环结构增加，相应的聚合程度增大，形成更大的芳香族化合物，进而促使半焦定向有序结构的形成。通过热重分析仪、傅立叶红外光谱仪（FT-IR）对MCTP化学结构和热行为进行了分析，发现MCTP总体产生更强烈的芳香族的C-H伸缩振动吸收峰和芳环骨架振动吸收峰。脂肪族的C-H伸缩振动吸收峰要弱很多。改性煤沥青拥有更好的热稳定性。改性剂最佳适量为5%。后将两种改性剂做了对比分析，同时对两种改性反应可能的机理进行了推测。 考察了温度、压力及机械振动对中间相微球生成的影响，得出了最佳炭化工艺条件。认为增大气压可以促使中间相小球生长速度加快，425℃为中间相最佳制备温度，适当的机械振动作用对于生成大小、分布都较为均匀的中间相微球有积极地促进作用。 采用偏光显微分析仪、XRD比较了机械振动作用对RCTP、MCTP制取半焦结构的影响。认为机械作用的存在对半焦的光学组织产生非常明显的影响。且施加的机械振动作用强度存在一个合适的振动频率。在机械振动的基础上，通过进一步D和G改性作用，纤维纹理方向行得到了进一步增强；机械作用和改性的存在能使半焦晶体面间距离减小，轴向晶体有序度增大。石墨化度提高。 采用SEM比较了机械振动作用对RCTP、MCTP制取针状焦结构的影响并做了电化学分析。增加机械振动针状焦结构有明显改善，呈现出有序层状结构。随着改性剂计量（超过5%后）的过度增加，反应体系过度交联，反而破坏了针状焦线性结构。通过改性和机械振动的作用提高了针状焦导电率。
[Abstract]:Needle coke is a kind of coke with very ordered structure and excellent performance. It has the advantages of low thermal expansion coefficient, high mechanical strength, high conductivity, low energy consumption and easy graphitization. Industrial applications are often used as raw materials for the preparation of high power HP-) and ultra-high power UHP-) graphite electrodes. However, compared with those produced in developed countries, the needle coke produced in China has many defects, such as high volume density and high resistivity. The needle coke in our country is still mainly imported, which seriously restricts the development of electric furnace steelmaking industry in China. Therefore, how to prepare high quality needle coke is of great significance to the coal chemical industry, which is rich in coal, lean oil and little gas. The physical and chemical properties of medium temperature coal pitch modified by G and D were studied, such as quinoline insoluble content, 尾 resin content, softening point, coking value and so on. The properties of modified coal tar pitch (MCTP) prepared with different mass ratio were analyzed. It was found that compared with the unmodified RCTP, the content of 尾 resin, SP and CV increased first and then decreased, and the content of QI increased with the increase of modifier content. The hydrogen NMR and elemental analysis of MCTP showed that the H content of modified MCTP decreased and the corresponding H / C ratio increased, and the proportion of aromatic hydrogen increased after modification. The corresponding polymerization degree increased to form larger aromatic compounds, which promoted the formation of oriented ordered structure of semi-char. The chemical structure and thermal behavior of MCTP were analyzed by thermogravimetric analyzer and Fourier infrared spectroscopy (FTIR). It is found that the C-H stretching vibration absorption peak and aromatic ring skeleton vibration absorption peak of MCTP are stronger than those of aromatic group. The C-H stretching vibration absorption peak of aliphatic group is much weaker. The modified coal pitch has better thermal stability. After that, the two modifiers were compared and analyzed. At the same time, the possible mechanism of the two modification reactions was speculated. The effects of temperature, pressure and mechanical vibration on the formation of mesophase microspheres were investigated, and the optimum carbonization conditions were obtained. It is considered that increasing the pressure can accelerate the growth rate of mesophase microspheres at 425 鈩

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