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.     

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。     

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。     

煤沥青热聚合研究

以煤沥青为原料,采用直接热聚合工艺制备出优质中间相沥青。研究了热聚合温度及保温时间对中间相沥青族组成及光学组织结构等性能的影响,并对反应机理进行了深入研究,得到了制备中间相沥青的最佳工艺条件。研究表明,在一定条件下,通过热聚合,在低温、长时间或高温、短时间都能制备优质中间相沥青。在360℃、5 h条件下制备的中间相球晶较小,分布较分散;而在380℃、4 h条件下制备的球晶较大,分布较集中。制备的中间相可作为高级炭材料的优质前躯体,为制取高质量的新型炭材料提供了一条新的途径,对煤炭资源的综合利用具有十分重要的意义。     

改性煤沥青在炭素生产中的应用

概述了沥青的分类和性质以及沥青改性、改性方法,讲述了在改性煤沥青生产应用中的要求,改性沥青的应用过程、效果和缺点。根据实验数据阐述了在改性煤沥青生产应用中的温度选择。结果表明,改性煤沥青特有的高软化点和粘度决定了在熔化、输送和混捏过程对温度的要求较高。数据分析表明软化点不能够准确指导下料温度,而粘度与下料温度呈正比例关系。因此,粘度可以作为下料温度的一个可靠的参考指标。     

Effect of erucic acid on the rheological and surface properties of coal tar pitch

Coal tar pitch (CTP) was modified using erucic acid, CH₃(CH₂)₇CH=CH(CH₂)₁₁COOH, and the rheological and surface properties of the modified CTP were evaluated. The effect of erucic acid was investigated using a rotational viscometer as well as by drop and weight tests. The modified CTPs were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy following a carbonization process. The results showed significant differences in several properties between the CTP and modified CTPs, such as decreases in viscosity, wetting temperature, and softening point when erucic acid content was 1–3 wt% of CTP. An improvement in bonding between the coke and the modified CTP can be achieved when the coke value remained 62%. Moreover, a modification mechanism was proposed to explain the physical plastification of CTP modified with erucic acid.     

煤沥青制备针状焦的研究

通过溶剂-离心法净化原料沥青,应用延迟焦化工艺制备针状焦,考察了在聚合过程中QI含量、温度、压力以及时间对成焦的影响.结果表明,原料中QI含量的减少有利于针状结构的生成,当QI含量小于0.1％时能形成大面积的针状结构;适当的温度和压力能使体系的黏度降低,促进气流拉焦作用,在470℃、0.35 MPa条件下得到的针状焦较为理想;充足的反应时间保证小球的充分融并,反应24h体系能融并、重排,形成良好的针状结构.     

聚乙二醇改性脱除煤沥青中3,4-苯并芘

以聚乙二醇为改性剂,研究在溶剂条件下降低煤沥青中3,4-苯并芘的工艺。研究表明,当混合溶剂V环己烷∶V甲苯=2∶1为反应溶剂、硫酸用量为煤沥青质量的6.67%、聚乙二醇600用量为煤沥青质量的10%、反应温度为80℃、反应时间为5h时,3,4-苯并芘降低率为85.59%。     

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。     

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.     

Catalytic reforming of coal tar pitch in supercritical fluid

This paper describes a new method to remove nitrogen from coal derived pitches, using catalytic hydrotreating in supercritical toluene-tetralin. The results obtained suggest that nitrogen was selectively removed from the mother pitch, the reaction rate was much higher than that in conventional processes due to higher diffusivity, and coke deposition on the catalyst could be prevented perhaps due to the high solvent power of the supercritical fluid.     

Carbon foams prepared from coal tar pitch for building thermal insulation material with low cost

A new approach is provided to resolve the large-scale applications of coal tar pitch. Carbon foams with uniform pore size are prepared at the foaming pressure of normal pressure using coal tar pitch as raw materials. The physical and chemical performance of high softening point pitch(HSPP) can be regulated by vacuumizing owing to the cooperation of vacuumizing and polycondensation. Results indicate that the optimum softening point and weight ratio of quinoline insoluble are about 292℃ and 65.7%, respectively. And the optimum viscosity of HSPP during the foaming process is distributed in the range of 1000-10000 Pa·s. The resultant carbon foam exhibits excellent performance, such as uniform pore structure, high compressive strength(4.7 MPa), low thermal conductivity(0.07 W·m~(-1) ·K~(-1)), specially, it cannot be fired under the high temperature of 1200 ℃.Thus, this kind of carbon foam is a potential candidate for thermal insulation material applied in energy saving building.     

Synthesis of nanoporous carbons from mixtures of coal tar pitch and furfural and their application as electrode materials

Synthetic nanoporous carbons are prepared by polymerization of mixtures containing coal tar pitch and furfural in different proportions, followed by carbonization of obtained solid product and steam activation of the carbonizate. The chemical composition of the initial mixture significantly affects the physicochemical properties (surface area, pore structure, electro resistance and amount of oxygen-containing groups on the surface) of the obtained materials. The incorporation of oxygen in the precursor mixture by means of furfural, has a strong influence in the synthetic step; increasing the furfural content facilitates the formation of a solid product characterized by a large oxygen content. Moreover, the solid product is more reactive towards activation as the furfural content increases, giving rise to nanoporous carbons with large surface areas and unique chemical features (high density of oxygen functionalities of basic nature). These nanoporous carbons have been investigated as electrodes in electrochemical applications.     

Coating of graphite anode with coal tar pitch as an effective precursor for enhancing the rate performance in Li-ion batteries: Effects of composition and softening points of coal tar pitch

Effects of compositions and softening points of coal tar pitches (CTPs) on the electrochemical performances especially for first cycle Coulombic efficiency and rate performance, of the amorphous carbon coating on the graphite surface were closely examined. CTPs with higher softening points could afford the better homogeneous amorphous carbon coating on the graphite surface, resulting in the better enhancing rate performance of graphite anode without decreasing the first cycle Coulombic efficiency. CTP with almost complete absence of hexane soluble (HS) fraction always showed the good enhancing effect of the rate performance. HS fraction of CTP, which is a reason for inducing surface defects on the coated carbon, hindered the enhancing effect of electrochemical performances. CTP derived amorphous carbon coating could effectively decrease charge transfer resistance on the graphite electrode–electrolyte interface.     

Fractionation of a coal tar pitch by ultra-filtration, and characterization by size exclusion chromatography, UV-fluorescence and laser desorption-mass spectroscopy

Ultra-filtration (UF) provides a new way of generating narrow bands of sample in the fractionation of coal and petroleum-derived liquids. It allows larger quantities of high-mass fractions to be recovered, making more detailed investigations possible, through the use of techniques requiring larger amounts of sample. In this work, UF-separated fractions have been used to study molecular mass distributions of a coal tar pitch, used as laboratory standard. The pitch was fractionated by solvent solubility into three fractions. These were further fractionated by ultra-filtration, using membranes specific to protein molecular sizes classed as “1 kDa”, “5 kDa”, “10 kDa” and “100 kDa”. Planar chromatography was used as a tertiary fractionation method, to sub-divide the UF-fractions. The various fractions were examined by size exclusion chromatography (SEC), UV-fluorescence spectroscopy and laser desorption-mass spectrometry (LD-MS). There was good agreement between mass estimates based on SEC and LD-MS of the smaller UF-fractions, with evidence for the presence of material with molecular masses ranging between 800 and 10,000 u. Examining the largest UF fractions of the pitch-pyridine-insoluble sample also gave clear evidence for material with molecular masses above 10,000 u. Taken together, however, the LD-MS data showed progressively diminishing differences, as the sizes of the UF membranes, and the likely molecular masses of the sample fractions, increased. One likely explanation is incomplete sampling during the laser desorption procedure. The evidence suggests that the upper mass limit detectable for these and similar samples by LD-MS has been reached. Despite these reservations, LD-MS appears as the best method to date, for investigating the mass ranges of samples derived from coal tar pitch and heavy petroleum fractions.     

Synthesis of photoluminescent SiC-SiOx nanowires using coal tar pitch as carbon source

SiC-SiOx nanowires (NWs) with core-shell and chain-bead structures were synthesized via a catalyst-free chemical vapor deposition (CVD) route without Ar gas, using silicon and coal tar pitch powders as raw materials. The SiC-SiOx NWs with sharp tips formed by solid-vapor between Si (s) and CO (g) or C (s) and SiO (g), liquid-vapor between Si (l) and CO (g), and vapor-vapor between SiO (g) and CO (g) growth process along the [111] direction. The NWs were several millimeters in length, and the average diameters of the chains and beads were 40–90 nm and 325 nm, respectively. The obtained NWs had good blue-green photoluminescence property owing to the stacking faults and amorphous SiOx. This novel CVD route is simple, low cost and suitable for large-scale production.     

Influence of oxidative stabilization on the electrochemical behaviour of coal tar pitch derived carbons in lithium batteries

A commercial coal tar pitch was thermally treated at 430 °C for 4 h and then submitted to hot filtration in order to separate the isotropic phase from the mesophase developed during the treatment. Each phase was then oxidatively stabilized in order to preserve its structure during carbonization and then carbonized at temperatures ranging from 700 to 1000 °C. The effect of the microstructure, particle morphology and chemical composition of the carbons and also the influence of their carbonization temperature on the electrochemical behaviour as electrode materials in lithium cells were studied.Galvanostatic cycling of lithium test cells using the carbon materials as positive electrodes showed the improvement of the electrochemical performance in both isotropic and anisotropic phases by stabilization with air previous to carbonization. More subtle differences between isotropic and anisotropic samples were evidenced and interpreted in terms of their textural properties. Moreover, the electrochemical impedance spectroscopy (EIS) has been demonstrated to be an interesting technique to elucidate the changes occurred in the electrode interfaces when these coal tar pitch based carbons are cycled.     

煤焦油沥青的深度利用及发展前景

煤焦油沥青的深加工对提高煤焦油沥青利用价值和经济性至关重要。本文主要概述了煤焦油沥青深加工利用的主要技术,重点概述了球形活性炭、中间相沥青、通用级沥青基碳纤维以及针状焦等。对各种产品的关键技术进行了分析,介绍了当前在各项关键技术方面的研究进展。煤焦油沥青基球形活性炭、通用级沥青基碳纤维以及针状焦已经得到了比较广泛的应用,当前研究的难点是提高各项产品的品质,缩短加工周期。另外,中间相沥青的发现与应用拓展了传统碳材料的应用领域,并大幅提高了炭材料的相关性能。     

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。     

Analysis of the carbonization and formation of coal tar pitch mesophase under dynamic conditions

Thermokinetic analysis of three pitch samples was carried out: coal tar pitch obtained from light coke oven tar (P), mesophase pitch after 10.5 h (MP1), and mesophase pitch after 12 h (MP2) thermopreparation at 410 °C. The process was realized in a continuous system with a 10 kg mass being charged to the reactor. It was demonstrated using Kissinger’s law that the temperature criterion, the first-order thermokinetics and the calculated Arrhenius law parameters fulfill the isokinetic effect when the classical routes of thermokinetic analysis of the samples prepared under dynamic conditions (at three heating rates) are used, which makes the qualitative interpretation of differences between these samples difficult. An alternative solution was proposed using the relative rate of thermal decomposition. The temperature ranges of the chemical reactions leading to the formation of mesophase structures, as well as the temperature ranges of the coking processes of the Fixed Carbon phase, were determined.