Influence of pitch additions on coal carbonization: Characterization of pitches

The technique of etching polished coke surfaces and examination by SEM was used to compare the abilities of a series of pitches to modify the carbon texture of cokes prepared from two low-rank coals. Cokes prepared from the pitches were similarly examined and a numerical texture index, the magnitude of which increased with increasing content of the larger textural components, was found to provide a useful measure of the ability of the pitches to modify the coke carbon texture.     

Improvement and control of the quality of binder pitch for graphite electrodes

Factors influencing the coke yield and the softening point (SP) of pitches were studied to ascertain procedures for the improvement and control of their quality. The coke yield of pitches from different tar sources is expressed as a linear function of the BI content. Pitches were prepared by distillation under constant operating conditions. The coke yields of pitches, determined by thermogravimetric analysis (TGA), increased with their benzene insoluble (BI) content, which is controlled by reflux heat treatment. Softening point increased with the nitrogen content as well as BI content. Therefore, increasing the BI content and decreasing the nitrogen content increases coke yield without any change in the softening point of binder pitches for graphite electrodes.     

热溶过滤法脱除煤焦油沥青中喹啉不溶物的研究

以5种煤焦油沥青为原料,喹啉为溶剂,研究了热溶过滤法脱除喹啉不溶物(QI)等杂质的效应,目的是制备QI含量较低的净化沥青。结果表明:热溶过滤法可以有效地脱除喹啉不溶物,QI脱除率随滤网网目增加而提高,但阻力增加,脱除时间变长。综合考虑脱除率和实际可操作性,采用1000目的滤布,QI含量可以降到0.3%以下,基本能达到要求。采用凝胶色谱对QI脱除后沥青的组成和分子量分布的研究表明,热溶过滤脱除了沥青中的大分子组分,分子量减小,分子量分布变窄。     

Hydrogen donor and acceptor abilities of pitch: 1H n.m.r. study of hydrogen transfer to anthracene

Petroleum pitches, coal-extract solutions and hydrogenated coal-extract solutions are co-carbonized with anthracene at 673 K. Chloroform-soluble fractions of the system are monitored by ¹H n.m.r. for formation of 9.10 dihydroanthracene (DHA). A hydrogenated coal-extract solution is also co-carbonized at 673 K with anthracene together with thianthrene and sulphur. Ashland A240 petroleum pitch and anthracene are co-carbonized with hydrogenated anthracene oil and resultant ¹H n.m.r. spectra are analysed for DHA. The pitches and coal-extract solutions are carbonized to 823 K and the optical textures of resultant cokes are assessed by optical microscopy. The purpose of the study is to assess if pitches which form cokes with larger optical textures or have greater abilities to modify the carbonization behaviour of coals also have the ability to act as ‘hydrogen shuttles’ in the carbonization system. Results would indicate that such pitches produce the largest amounts of DHA. It is proposed that the most efficient of the modifying pitches operate by extending the zone of temperature of maximum fluidity and by increasing the value of maximum fluidity by removal by proton transfer of radicals which if left in the carbonizing system would interact to form cokes of smaller optical texture.     

Carbonization and liquid-crystal (mesophase) development. 17. Co-carbonization of a solvent-refined coal with petroleum pitches and hydrogenated coal-extract solution

This study characterizes the optical textures of cokes prepared by the carbonization of Ashland petroleum pitches, of non-hydrogenated and hydrogenated coal-extract solutions (CES) and of blends of non-hydrogenated CES materials with the petroleum pitches and hydrogenated CES materials. At an HTT of 823 K petroleum pitches produce cokes with large sized optical texture of flow-type anisotropy characteristic of needle-cokes. The non-hydrogenated CES materials produce cokes with optical textures of mozaics, 2–10 μm. However, following hydrogenation the CES materials carbonized to cokes all of which possess considerable large sized optical textures which for some materials resemble that of needle-cokes by possessing strong flow-type anisotropy, > 100 μm. Hydrogenation of the CES materials evidently facilitates the physical and chemical requirements for growth and coalescence of lamellar nematic liquid-crystals and mesophase from the fluid phase of carbonization leading to anisotropic carbon. Co-carbonizations of the non-hydrogenated and hydrogenated CES materials exhibit the dominant partner effect and are comparable in behaviour with Ashland petroleum pitches which are known to produce needle-cokes on carbonization.     

A novel method to obtain a petroleum-derived mesophase pitch suitable as carbon fibre precursor

This paper studies a novel method for the preparation of mesophase pitches suitable as carbon fibre precursors. A series of thermally treated petroleum pitches with mesophase contents ranging from 10.8 to 52.2 vol.% was obtained from pitch A-240. Separation of the phases was initially attempted by hot filtration, a suitable method for separating the phases in thermally treated coal-tar pitches. Although filtration failed for the petroleum samples, the behaviour observed led to the development of a new separation method that consists in the sedimentation of the mesophase. This method, after optimisation, yielded pitches with mesophase contents up to 97 vol.%, which were easily spun into carbon fibres of reasonable mechanical properties.     

不同馏程闪蒸油制预炭化沥青的热解行为及其性质研究

用差示扫描量热法（DSC）、热重法（TG）、微商热重法（DTG）分析研究了不同馏程的两种闪蒸油的预炭化沥青的热解行为。用偏光显微镜观察了两种预炭化沥青的炭化产物的光学显微结构,分析了两种预炭化沥青的性质。     

沥青球平均粒径与成球原料粘度相关性的研究

选用了3种典型煤沥青为初始原料，通过助剂配合法将其分别调制为精制沥青，再采用介质分散法将其制成普通沥青球(OPS)。考察了不同温度下成球原料的粘度和OPS平均粒径的变化特点，并将二者进行并联。试验发现，经调制的成球原料的粘度对数值与OPS的平均粒径随着温度的变化具有规律性。两参数之间的关系可以用简单线性回归方程表达。     

沥青炭化后显微结构的研究

采用中温沥青、改质沥青、浸渍沥青3种沥青试样,经过两种不同温度曲线炭化后,利用偏光显微镜、扫描电镜分析煤沥青炭化后的显微结构特征。结果表明,3种沥青炭化后的显微结构有所区别,不同的温度曲线对沥青炭化后的显微结构有一定影响。     

Determining the anisotropic content in a petroleum pitch - Comparison of centrifugation and optical microscopy techniques

The anisotropic content of a pitch is one of the most important parameters for characterizing such materials. Polarized light optical microscopy is the technique most commonly employed (ASTM D 4616 standard procedure) to measure this pitch parameter. However, this standard procedure is limited to pitches with mesophase contents only up to 20%. An alternative technique for determining the anisotropic content of a pitch is high-temperature centrifugation, which can be used without limitation for pitches with up to 100% anisotropic content. In this work, the two techniques have been compared; samples of four pitches with mesophase contents lower than 20% have been analyzed by both techniques and the results have been compared. The high-temperature centrifugation technique showed good repeatability, and the results that it yielded matched those obtained from optical microscopy when the anisotropic content of the pitch was higher than around 5%. The centrifugation technique is always faster, simpler, and possibly more accurate than optical microscopy for pitches with mesophase contents higher than 20%.     

升温速率对煤沥青热解缩聚的影响

用TGA对煤沥青的热失重过程进行了研究,分析了煤沥青的热解缩聚特征,并对中温沥青和改质沥青热解缩聚行为进行了比较,研究了升温速率对煤沥青热解缩聚的影响,发现快速升温使煤沥青组份更多地分解逸出,不利于提高煤沥青的结焦值。     

基于CATIA/CAA的轮胎多节距自动装配

针对企业在轮胎设计中存在多节距装配困难,效率低的问题,提出一种轮胎多节距自动化装配方法,并在CATIA平台上进行了应用。在分析轮胎花纹节距装配的约束参数及约束关系的基础上,给出了节距装配方法;讨论了对基于CATIA/CAA的虚拟装配技术及实现方法,采用二次开发方式开发了多节距自动装配工具,并给出装配实例,验证了本文方法的有效性。测试表明,该程序可以减少轮胎多节距装配过程中存在的大量重复性工作,快速准确完成多节距自动装配。     

Carbonization of pitch: Compatibility of components in carbonization

The carbonization of four kinds of solvent-refined-coal (SRC) pitches was investigated in order to determine the properties required for the formation of needle coke. Although the pitches were free from Ql materials, two of them gave needle cokes, whereas the other two gave mosaic cokes. The BS fractions of all pitches formed needle cokes, and all Bl fractions were infusible and isotropic. A combination of suitable BS and Bl fractions gave a needle coke, whereas another mixture formed a mosaic coke, indicating that the BS and the Bl fractions can be compatible to yield a needle coke. Cocarbonization of the BS fractions from other pitch sources with the Bl from the SRC pitches was further studied to evaluate the compatibility, which has been discussed from the structural viewpoint. Trials to improve the properties were proposed, based on the structural information.     

Stabilisation of low softening point petroleum pitch fibres by HNO3

This paper deals with the stabilisation of low softening point pitch fibres obtained from petroleum pitches using HNO₃ as oxidising agent. This method presents some advantages compared with conventional methods: pitches with low softening point (SP) can be used to prepare carbon fibres (CF), the stabilisation time has been reduced, the CF yields are similar to those obtained after general methods of stabilisation, and the initial treatments to increase SP when low SP pitches are used to prepare CF, are avoided. The parent pitches were characterised by different techniques such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), elemental analysis and solvent extraction with toluene and quinoline. The interaction between HNO₃ and the pitch fibres, as well as the changes occurring during the heat treatment, have been followed by DRIFTS.     

Study of the modification of coal-tar pitch with p-methyl benzaldehyde

Coal-tar pitch is modified with p-methyl benzaldehyde (PMB) in the presence of p-toluene sulfonic acid (PTS). The main characteristics of the modified pitches such as coking value, softening point and solubility are studied in this paper. The molecular structures of the modified pitches are studied using FT-IR and ¹H-NMR spectroscopy techniques. In addition, the morphologies of the modified pitches are inspected with SEM, and the optical textures of resultant semi-cokes are characterized by polarized-light microscopy. Results show that the modified pitches have much higher coking value and β-resins content than the parent pitch. There exist many microfibers with a uniform distribution in the modified pitches. Moreover, the modification results in an improvement in the optical textures of resultant semi-cokes.     

Correlations between ability of pitch to penetrate coke and the physical characteristics of prebaked anodes for the aluminium industry

The nature of the interaction between coke and pitch is basic to the final properties of anodes for the aluminium melting industry. One of the significant properties of pitch which contribute to the quality of this binding is its ability to wet coke. The investigations reported here indicate the optimum experimental conditions for the use of an automatic apparatus that monitors pitch penetration into a coke bed. The penetration test described can be used to select pitches with good affinity for petroleum coke and to correlate this quality with the physical properties of electrodes produced therefrom. A particularly important conclusion is that the test suggests the suitability of certain pitches which would not satisfy the usual selection criteria. The temperature-dependent ability of a pitch to penetrate a coke bed, in conjunction with the traditional criteria, assists in the selection of binder pitches used in the aluminium industry.     

Carbonization of coal-tar pitches: effect of rank of parent coal

The object of the present work was to investigate whether the rank of coal from which the coal-tar pitches were obtained had any bearing on their carbonization behaviour. Using six laboratory produced pitches it is shown that the behaviour during the mesophase temperature range, and consequently the size of the anisotropic flow structures in the pitch coke, vary with the rank of the parent coal.     

Estimation of hydrogen mobility of coal tar pitch for carbon fiber using a tritium tracer method

Three coal tar pitches for high performance carbon fiber (HPCF) and general performance carbon fiber (GPCF) were hydrogenated by tritium labelled gaseous hydrogen in the absence of both catalyst and vehicle solvent under conditions of temperature 300–400°C, nominal reaction time 0–300 min and initial hydrogen pressure 5.9 MPa. The relative rate constants and apparent activation energies for hydrogen transfer from gas phase to the pitches have been estimated by tracing tritium. The apparent activation energies for hydrogen addition from the gas phase to the three pitches were very close (ca. 9–10 kcal/mol), but apparent activation energies for hydrogen exchange between the gas phase and the three pitches were different from each other (HP, 15.4; GP-A, 2.9; GP-B, 3.7 kcal/mol). Especially, apparent activation energy of hydrogen exchange of the raw pitch for HPCF was significantly larger than those of the raw pitches for GPCF. These results of kinetic parameters for hydrogen transfer can be used to evaluate the distribution and mobility of hydrogens in component molecules of pitches.     

TI-PS组份对沥青性能的影响

通过考察不同比例ＴＩ－ＰＳ组份沥青的软化点、残炭值和粘度，发现在ＰＩ组份或ＴＳ组份不变情况下，随着ＴＩ－ＰＳ组份的改变沥青的三种性能参数值呈直线变化。实验表明，有机酸催化可提高沥青ＴＩ－ＰＳ组份的含量，而改变原料沥青的组成与结构也可得到同样效果。     

Preparation and characterization of spinnable pitch for general-purpose carbon fiber from refined pitch

Four types of spinnable pitches (MP-N-A, MP-A, MP-A-H, and MP-A-N) for general-purpose carbon fiber have been prepared under certain conditions with the refined pitch as the raw materials. Fourier transform infrared spectrum and solid-state nuclear magnetic resonance spectra combined with curve-fitting analysis have been used to characterize the average molecular structure (I_ar, CH₃/CH₂, S_AR, and S_HFG) of spinnable pitches. Thermogravimetric analyses and polarizing microscope have been used to observe the thermal stability and the microstructure of spinnable pitches, respectively. The X-ray diffraction combined with curve-fitting analysis have showed that, the stacking heights (L_c) of these four kinds of spinnable pitches were 2.21, 1.78, 1.79, and 1.76 nm, respectively. The parallel layers (N) of each spinnable pitch were 7.30, 6.02, 6.06, and 5.97. What is more, the numbers of aromatic ring in each layer (n) were 17.03, 11.61, 11.75, and 11.41. Finally, the scanning electron microscopy has been used to characterize the surface morphology of carbon fibers which obtained by each spinnable pitches. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47880.