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1.
《Carbon》1986,24(4):417-421
The concentration of secondary quinoline insolubles (SQI) in coal tar pitches corresponds to the increase of quinoline insolubles (QI) due to the heat treatment. A series of experimental pitches was used for the analytical estimate of SQI by several methods sensitive to heat treatment.The determination of the size of QI by small angle, forward-scattering light from a laser beam projected through a stream of isolated QI dispersed in toluene yielded results most suitable for the quantitative estimate of SQI concentration in heat treated coal tar pitches. 相似文献
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David R. Ball 《Carbon》1978,16(3):205-209
Seven pitches containing three types of quinoline insolubles, QI, were produced from a single coke oven coal tar. The tar was centrifuged into QI-rich and QI-lean fractions. A blend of the two fractions yielded a typical graphite electrode binder pitch. The QI content of the pitch derived from the QI-lean tar was increased through the addition of natural QI concentrate, or QI as a furnace carbon black, or QI as mesophase by means of heat treatment. The pitches were evaluated as binders by measuring the flexural strength of 19 mm diameter graphite electrodes. The results show that the typical electrode pitch is superior, and that increasing the QI content of the QI-lean material did not upgrade it. The results also show that the flexural strength of the derived graphite is not simply related to the coking value of a binder. 相似文献
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G.R. Romovacek 《Carbon》1985,23(6)
A new method for the determination of quinoline insolubles (QI) in tars and pitches, using elevated pressure instead of vacuum for filtration was developed. The apparatus is described and the outline of the procedure is given. The procedure was simplified by omitting the addition of filter aid and washing the filter cake with toluene. 相似文献
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Isao Mochida Keiko Kudo Kenjiro Takeshita Ryohei Takahashi Yoshio Suetsugu Jyuji Furumi 《Fuel》1974,53(4):253-257
Reactivities of benzene-insoluble/quinoline-soluble matter (QS—BI) and quinoline insolubles (QI) of coal-tar pitch in reductive alkylation and hydrogenation with the aid of alkali metals were investigated, to obtain basic information on the possibility of changing their graphitizability and the orientation of their cokes. Alkylation increased the solubility in benzene of both components; however only the soluble fraction of QS—BI was fusible. In contrast, the soluble fractions produced by hydrogenation from both QS—BI and QI were fusible giving a flow-pattern structure and graphitizable carbon. Fusibility of pitches in the early stage of carbonization is discussed from the viewpoints of graphitization and orientation of cokes obtained by subsequent heat treatment. 相似文献
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热溶过滤法脱除煤焦油沥青中喹啉不溶物的研究 总被引:3,自引:1,他引:3
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。 相似文献
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精制沥青是制备各种功能炭材料的前体,焦油沥青需要预处理脱除其中的固体颗粒物(称为喹啉不溶物,QI)以得到精制沥青,压力是脱除QI的重要条件。本文以煤焦油沥青和添加生物质沥青的混合沥青为原料,研究压力对溶剂法脱除固体颗粒物的影响,测试不同压力下精制沥青的QI含量及产率,利用纳米粒度分析仪、扫描电子显微镜和高温黏度测定仪对QI颗粒形貌、粒度及脱除体系黏度进行表征和测定,分析压力对固体颗粒物絮凝沉降的影响规律。研究结果表明,增加压力对沥青收率升高有明显影响,使精制煤焦油沥青的收率由常压的64.6%(质量分数)提升至1MPa时的84.3%(质量分数),精制沥青的QI含量维持在0.06%~0.1%(质量分数)之间。添加15%生物质沥青的混合沥青,产率则由常压时的55.7%(质量分数)提升至1MPa时的72.5%(质量分数)。压力对精制沥青的QI含量影响较小,压力增大,溶剂对沥青组分尤其是重质组分的溶解能力增强,使精制沥青产率升高。较高压力也使体系的黏度略微增大,造成部分QI颗粒沉降困难,不过影响较小。中间相沥青制备的结果表明,精制沥青可以制备出具有流域型结构的中间相沥青,添加生物质沥青更好地改进了流域型的显微结构。 相似文献
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Modification of the carbonization properties of coal-tar pitch by supercritical fluid extraction 总被引:1,自引:0,他引:1
The carbonization properties of coal-tar pitch were modified by supercritical fluid (SCF) extraction. Pitches extracted with supercritical toluene (SCFE pitch) contained none of the quinoline insoluble (QI) matter responsible for anisotropic structures with small unit sizes. The size of anisotropic structures from SCFE pitches was closely related to the β-resin (toluene insoluble and quinoline soluble fraction) content. Anisotropic structures from blended pitches prepared to have the same β-resin content as SCFE pitches (by blending toluene soluble (TS) and β-resin fractions obtained through a conventional liquid solvent extraction) were smaller. Extraction of the β-resin fraction with supercritical toluene could be interpreted by the co-solvent effects of the TS fraction dissolved in the extract phase. The high concentration of TS fraction in the extract phase enhanced the solubility of the β-resin fraction into this phase. In the raffinate phase, the heavier β-resin components, which are unsuitable for the development of mesophase structures, coagulated and formed unextractable QI matter through reduction in the concentration of the TS fraction. Since the TS concentration in both the phases depends on pressure and the ratio of the amounts of supercritical toluene and pitch, the control of the β-resin content in the SCFE pitches is possible through the adjustment of these two parameters. 相似文献
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Koji Ouchi Akihiko Mikami Hironori Itoh Masataka Makebe 《Fuel Processing Technology》1985,11(3):231-240
Yubari coal vitrite was extracted with quinoline at 420° C for 0–4 h and the products were separated into several fractions. Quinoline solubles (QS) and insolubles (QI) increased with time and the total recovered weight became nearly 200% of the original weight of the coal. A large part of this weight increase was due to the contribution of the formation of biquinoline and to quinoline addition to coal. Depolymerization to smaller molecules and polymerization to QI took place simultaneously via the addition of quinoline and the production of biquinoline. 相似文献
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The microstructure of nuclear graphite binders 总被引:1,自引:0,他引:1
The microstructures of the binder in two grades of nuclear graphite, Gilsocarbon graphite and Pile Grade A graphite, were characterized by light microscopy, transmission electron microscopy and high resolution transmission electron microscopy. A variety of structures of carbon were observed, including a well-graphitized structure, nanosized graphite particles, quinoline insoluble (QI) particles, chaotic structures and non-graphitizing carbon. QI particles were observed on the surface of mesophase spheres as well as inside mesophase spheres. The aggregation of QI particles on the surface of mesophase spheres, or very near the surface in mesophase spheres, appears to have a significant influence on the development of the mesophase structure, resulting in refinement of the mesophase spheres before their coalescence. The chaotic structure, which is turbostratic and isotropic, is suggested to have developed from the isotropic pitch remaining between mesophase spheres. The non-graphitizing carbon consisted of flat and curved single layer graphene fragments with a size typically less than 1 nm. The formation of the various structures in the two graphites is attributed to the introduction of different pitches at stages of the graphite manufacture. 相似文献
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《Carbon》2002,40(11):1937-1947
Modified pitches with softening points of about 175 °C were prepared by air-blowing at 300 °C of coal-tar pitches from different commercial coke-oven tars. The modifications induced by the mild oxidation were monitored using solvent and extrographic fractionation, elemental analysis, 1H NMR and HPLC. Optical microscopy was used to follow the effect of air-blowing on carbonization behaviour. Low molecular weight cata-condensed PAHs and those with basic nitrogen and hydroxylic functionalities present in extrographic fractions F2 and F4, respectively, are preferentially polymerized pitch constituents. In contrast, peri-condensed PAHs in extrographic fractions F2 and F3, are practically unreactive under the oxidation conditions used. The mild oxidation enhances the tendency of quinoline insoluble (QI) particles to form aggregates in an early stage of thermal treatment, modifying the mode of mesophase development and leading to a non-homogeneous optical texture. The enhanced propensity of QI to aggregation is discussed in terms of structural peculiarities of the parent pitch and possible oxidative polymerization reactions. 相似文献
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《Fuel》1987,66(11):1540-1543
The relationship between the rate of secondary quinoline insoluble (QI) formation in coal-tar pitches and variations in their chemical composition is examined. Production of significant concentrations of secondary QI is shown to be accompanied by mesophase formation, the significance of which is discussed in terms of electrode binder performance. 相似文献
14.
The influence of organic sulfur compounds and metals on the texture of the mesophase formed in pitch during the carbonization process was investigated by the addition of organic sulfur compounds and organometallic compounds to the cracked oil obtained from Khafji asphalt and polyvinyl chloride (PVC) pitch. These pitches, containing sulfur and metals, have been examined by polarised light microscopy, and quinoline insolubles (QI), sulfur and metal contents were determined. The existence of either organic sulfur compounds or organometallic compounds in the pitch has no effect on mesophase texture. However, the coexistence of sulfur and metals (such as vanadium or nickel) has a great effect on mesophase texture. From these results, sulfur and metals coexisting in the pitch have a catalytic effect which activates the thermal decomposition and the thermal polymerization reactions of the pitch. Furthermore, the precursors of mesophase (β resin) are formed abundantly in the pitch by these reactions. These precursors promote the nucleation of mesophase spherules, and a large number of mesophase spherules are formed in the pitch at the same time. Therefore, these spherules coalesce with each other before growing to large spheres and lead to a fine mosaic texture. 相似文献
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煤焦油是一种制备高附加值碳材料的理想原料,然而其深加工利用受到内部高含量喹啉不溶物(QI)的影响。为此,本文介绍了煤焦油的组成和性质,简述了煤焦油中QI的组成、来源和其对煤焦油加工利用的危害,综合对比分析了煤焦油净化分离常用的几种方法。热过滤法分离效率虽然满足工业需求,但工业成本较高;重力沉降法操作简单,但分离效率低;离心分离法分离效率高,但处理量小,难以满足工业化应用;蒸馏处理法分离效率高,但原料利用率低;溶剂萃取法容易操作,但溶剂需求量大;改质法效果明显,但成本较高;静电分离法能量消耗低,但静电分离最佳条件变动性较大;联合处理法分离效率较高,应用前景广阔,可以作为一种净化分离的科学有效方法,并可以作为一种净化分离技术的发展趋势。 相似文献
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《Fuel Processing Technology》2004,85(15):1671-1687
Point of Ayr coal has been extracted using three solvents, tetralin, quinoline and 1-methyl-2-pyrrolidinone (NMP) at two temperatures 350 and 450 °C, corresponding approximately to before and after the onset of massive covalent bond scission by pyrolysis. The three solvents differ in solvent power and the ability to donate hydrogen atoms to stabilise free radicals produced by pyrolysis of the coal. The extracts were prepared in a flowing solvent reactor to minimise secondary thermal degradation of the primary extracts. Analysis of the pentane-insoluble fractions of the extracts was achieved by size exclusion chromatography, UV-fluorescence spectroscopy in NMP solvent and probe mass. With increasing extraction temperature, the ratio of the amount having big molecular weight to that having small molecular weight in tetralin extracts was increased; the tetralin extract yield increased from 12.8% to 75.9%; in quinoline, increasing extraction temperature didn't have an effect on the molecular weight of products but there was a big increase in extract yield. The extracts in NMP showed the enhanced solvent extraction power at both temperatures, with a shift in the ratio of larger molecules to smaller molecules with increasing extraction temperature and with the highest conversion of Point of Ayr coal among these three solvents at both temperatures. Solvent adducts were detected in the tetralin and quinoline extracts by probe mass spectrometry; solvent products were formed from NMP at both temperatures. 相似文献