Rheological characteristics of coal tar and petroleum pitches with and without additives

An extensive study of rheological characteristics of coal tar and petroleum pitches with and without additives, namely, petroleum coke, natural graphite and carbon black has been made. It is found that all pitches, pure or mixed with a carbon additive are not Newtonian as reported in the literature, but behave Theologically as Bingham plastics with certain yield stress and plastic viscosity at all temperatures of measurement between 85–180°C. The yield stress and plastic viscosity both decrease with increase in temperature of the pitch. A pure petroleum pitch having the same softening point as that of a coal tar pitch is found to have a lower viscosity compared to that of the latter at all temperatures of measurement. This suggests that the criterion of softening point as a measure of suitability of a coal tar pitch binder in the manufacture of artificial carbon is not sufficient for petroleum pitches. Addition of ten parts of carbon black by weight of pitch results in a considerable decrease in viscosity change with temperature of the coal tar pitch compared to almost insignificant change in the case of the petroleum pitch of the same softening point. However, the addition of petroleum coke or natural graphite makes the pitch more viscous but does not change the temperature dependence of viscosity of either of the two types of pitches. The implications are discussed.     

Production of petro/coal tar pitch by joint distillation of coal tar and heavy pyrolytic oil

The properties of petro/coal tar pitch and distillate fractions obtained in the joint distillation of coal tar and heavy pyrolytic oil from ethylene production are described. The petro/coal tar pitch is particularly reactive in heat treatment and air-blowing. The petro/coal tar pitch may be used as less carcinogenic binder and impregnating electrode pitch.     

贫煤与煤沥青共炭化研究

进行了不同配比的煤沥青和贫煤的共炭化研究,研究表明,煤沥青与贫煤共炭化时的相互作用是物理融合和化学相互作用的共同作用。其中物理融合表现在使焦炭界面结合状态改善,化学相互作用表现在煤沥青使贫煤的炭化性能发生变化。随煤沥青配比的增加,配煤黏结性有较大改善,焦炭OTI值增大,ISO值减小。煤沥青通过增大焦炭光学组织各向异性程度,使焦炭的反应性降低,反应后强度提高。     

Centrifuge treatment of coal tar

New technology is required for the removal of water and heavy fractions from regular coal tar. Centrifuges offer the best option. Purification of coal tar by means of centrifuges at OAO NLMK permits the production of pitch coke or electrode pitch that complies with current standards.     

Preparation of micro-porous monolithic activated carbon from anthracite coal using coal tar pitch as binder

Monolithic activated carbon (MAC) has been produced from steam activation of monoliths prepared by mixing coal powders with high-temperature coal tar binder for a long time. However, this process leads to poor working conditions, environmental pollution, and waste of resource. This study investigated the use of coal tar pitch as binder to prepare MAC with high surface area, micro-pore structures, and strong mechanical strength. The performances of the MACs with both coal tar and coal tar pitch as binders were compared. The product yield of MAC bonded with coal tar pitch (MAC_p) was 10% higher than that with coal tar (MAC_T). The BET surface area, micropore volume, and average pore diameter of MAC_P were 837.99 m² g^?1, 0.346 m³ g^?1, and 1.776 nm, respectively, which were all superior to the corresponding values of MAC_T. Only the attrition resistance strength of MAC_P was slightly lower than that of the MAC_T. The SEM images showed that the cokes on the surface of both MACs distributed identically and uniformly. Furthermore, XRD results revealed that the pore-expanding reactions mainly led to the reduction of carbon crystallite along with the stacking direction rather than horizontal direction during steam activation process. This work demonstrates that cost-effective MAC can be prepared with the coal tar pitch as binder and the results of the investigation presented in this work provide new and important information necessary to the successful application of MACs in industrial field.     

煤沥青基功能碳材料的研究现状及前景

我国煤沥青资源丰富,但深加工技术落后,产品附加值低,实现煤沥青高附加值利用是亟待解决的重大课题。本文介绍了以煤沥青为原料合成高性能功能碳材料的主要技术,重点阐述了以煤沥青为原料制备中间相沥青、多孔碳材料、碳纤维、二维纳米碳材料及碳基复合材料的研究进展。分析表明,高芳香性和高缩合度分子结构所引起的强π-π相互作用是阻碍煤沥青基高性能功能碳材料设计合成的瓶颈问题。通过催化聚合、氧化、共热解等技术手段可有效改善煤沥青分子结构及其物理、化学性质。结合模板复制、物理/化学活化、界面诱导以及催化石墨化等技术可实现多种功能性碳材料结构设计与表面化学性质调控。发展煤沥青分子结构调控新技术作为改善煤沥青基碳材料性能的重要策略,需要系统深入研究。     

煤焦油的性质与加工利用

煤焦油的深加工可以减轻对石油产品的±赖。简要介绍了中低温煤焦油与高温煤焦油的性质和组成,发现原料煤种、热解工艺不同,生产的煤焦油的组成和性质也有较大差别。重点从煤焦油蒸馏前的准备,焦油蒸馏工艺,煤焦油馏分的加工,煤焦油加氢改质4个方面介绍了煤焦油的加工工艺。最后根据煤焦油中的馏分,介绍了其加工产品的用途。     

复合纳米材料的制备及对路用煤沥青的改性研究

通过水热共沉淀法制备了改性纳米复合材料,利用比表面积、TEM和接触角对其进行了表征。将改性纳米复合材料应用于路用煤沥青的改性中,结果显示该纳米改性煤沥青的性能指标完全达到了90#路用石油沥青指标,可以应用于实际道路的铺设。     

煤沥青的最新研究进展

综述了最近几十年国内外对煤沥青的主要分析方法和以它为原料在制备沥青基中间相、中间相炭微球、针状焦、活性炭、泡沫炭和高性能炭/炭复合材料基体方面的研究和进展,展望了其在材料领域潜在的应用前景和未来发展的趋势.     

芳香族硝基化合物改性煤沥青研究

以煤沥青为原料,通过添加不同含量的芳香族硝基化合物对煤沥青进行改性处理,采用TG、CO2反应性、XRD和SEM对改性沥青焦进行表征。结果表明,芳香族硝基化合物有效地促进了煤沥青在炭化过程中的焦化缩聚,使产物沥青焦结构更加致密,并在一定程度上改变了沥青焦的氧化行为,从而显著提高了沥青黏结焦的抗氧化性能。     

煤沥青对我国铝用炭阳极质量的影响

论述了国产铝电解炭阳极用煤沥青的现状和最新趋势,研究了煤沥青对炭阳极质量的影响,指出我国炭阳极用煤沥青存在的技术标准与大型预焙阳极技术不适宜、质量波动、科研滞后等问题,提出了改进建议。     

Use of coal tar pitch and petroleum bitumen in the production of thermally expanded graphite (short communication)

The applicability of coal tar pitch and petroleum bitumen to the production of thermally expanded graphite was studied. The dependence of the coefficient of thermal expansion and the specific surface area on the amount of added substances was examined.     

Benefits of ultrasound in pitch production from coal tar and its mixtures with styrene distillation residue

Ultrasound treatment of coal tar increases the yield of pitch by a factor of 1.5 in subsequent oxidation by atmospheric oxygen. The yield of pitch may be regulated in terms of its softening temperature by changing the oxidation time. To obtain standard pitch, the following conditions are employed: ultrasound treatment for 3 h; initial oxidation temperature 260–270°C; final oxidation temperature 360–370°C; rate of air supply 63 L/h; oxidation time ~30–70 min, depending on the requirements on the final product. The concentration of aromatic derivatives of benzo[a]pyrene type in the pitch produced and in the liquid fraction (which may be used as a fuel) is considerably less than in the current industrial method. After ultrasound treatment, a 1: 1 mixture of coal tar and rectification residues from styrene yields pitch with satisfactory characteristics on oxidation by atmospheric air. That expands the range of raw materials for pitch production.     

溶剂效应对脱除煤沥青中3,4-苯并芘的影响

研究了单种溶剂、混合溶剂对3,4-苯并芘的溶解选择性及煤沥青溶解量。并以顺丁烯二酸酐为改性剂、硫酸为催化剂,考察了溶剂效应对降低煤沥青中3,4-苯并芘的影响。研究表明,环己烷、甲苯,环己烷、乙酸丁酯组成的混合溶剂具有较好的3,4-苯并芘溶解选择性和合适的煤沥青溶解量。当环己烷∶甲苯=2∶1（体积比）和环己烷∶乙酸丁酯=2∶1（体积比）为反应溶剂时,能够高效地脱除煤沥青中3,4-苯并芘,煤沥青中3,4-苯并芘降低率分别达到88.26%和90.83%。其原因认为是此类溶剂能使包裹在沥青颗粒内部的3,4-苯并芘释放出来,且3,4-苯并芘与改性剂能够形成均相反应体系,大部分不具有致癌性的高相对分子质量环芳烃与改性剂之间形成两相体系,从而提高了改性剂与3,4-苯并芘的有效反应。     

Modified characteristics of mesophase pitch prepared from coal tar pitch by adding waste polystyrene

The toluene soluble of coal tar pitch was carbonized with waste polystyrene. The properties of mesophase pitches were characterized using polarized light optical microscope, apparent viscometer, FT-IR, ¹H NMR and X-ray diffractometer. After adding the waste polystyrene into the toluene soluble of coal tar pitch, the soluble mesophase were was increased from about 9% to 52% and the mesophase pitches were changed from 74% with coarse mosaic texture to 100% with flow domain texture. The mesophase pitches were transformed from thixotropy to unthixotropy. By waste polystyrene added into the toluene soluble of coal tar pitch, the methylene group was increased a lot. The presence of more alkyl groups modified the characteristics of mesophase pitches and improved the assembly of mesophase pitch molecules.     

煤焦油中渣相的分析及应用

分析了煤焦油中渣相的性质,其具有很强的反应性,可作为一些沥青反应添加剂使用,并在应用方面做了一些阐述.     

CO2 separation by carbon molecular sieve monoliths prepared from nitrated coal tar pitch

The objective of the present work is to develop a simple procedure, which avoids the need of a binder, to obtain activated carbon monoliths from a waste precursor (coal tar pitch) suitable for CO₂ capture and/or separation. The main task of this process consists of a nitration process of the coal tar pitch. This nitration step over the coal tar pitch is characterised by different techniques, such as infrared spectroscopy and thermogravimetric analysis. The nitration treatment produces the oxidation of the pitch molecules, leading to hydrogen consumption and generating oxygenated and nitrogenated surface complexes. As a consequence of this oxidation, nitrated coal tar pitch is an infusible material, which allows the carbonization of monolithic pieces avoiding their fusion. Decomposition of these surface complexes during the carbonization of monoliths generates narrow microporosity, which is suitable for CO₂ capture from gas streams at room temperature. The molecular sieving properties of these materials are studied by CH₄ and CO₂ adsorption kinetics.     

煤焦油沥青树脂黏结剂的制备研究

采用交联合成法,以煤焦油为原料,多聚甲醛为交联剂,在酸性催化剂对甲苯磺酸的作用下制备煤焦油沥青树脂。采用正交试验法研究了交联剂量、催化剂量、反应温度和反应时间对合成煤焦油沥青树脂的影响。结果表明,增加交联剂量和催化剂量可以起到降低反应温度和缩短反应时间的效果;煤焦油沥青树脂的软化点、结焦值和黏结强度等指标均随反应温度升高和反应时间延长而明显增加。     

Slurry removal from tar

We know that increasing the water content in coal tar above 4% and the ash content above 0.1% hinders its processing: soda consumption is increased; greater heating is required in dehydration; and it is impossible to comply with standards regarding the ash content in pitch coke and electrode pitch. Recently, the trend has been to introduce a centrifuge ahead of the final tar store in systems for conditioning coal tar.     

Anomalous capillary flow of coal tar pitches

Capillary flow of liquid coal tar pitch into a coke bed was studied. Anomalies in the flow could not be attributed to a plugging effect for mesophase content lower than 20 wt%. The flow behaviour of small pitch droplets can be correlated with the change in physicochemical properties, as measured by the glass transition temperature, on penetration into the coke bed.