Preparation and characterization of pitch-based mosaic coke from heavy-phase coal pitch: Effects of quinoline insoluble
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摘要: 镶嵌结构沥青焦作为一种特种人造炭材料,是制备高品质各向同性石墨和核石墨的重要原料。镶嵌结构沥青焦的性质在很大程度上决定了其石墨制品的质量。为进一步明确重相沥青中QI含量对其镶嵌结构沥青焦的结构及性质的影响,本研究以九种QI含量迥异的重相沥青为原料,制备了系列镶嵌结构沥青焦。利用偏光显微镜、扫描电镜、XRD、Raman光谱及分峰拟合的方法对镶嵌结构焦的微观结构进行了判定,并对九种镶嵌结构沥青焦的显微强度进行了研究。结果表明,重相沥青中QI含量越高,在液相炭化过程中越有利于镶嵌结构的生成。并且,随着重相沥青QI含量的增加,镶嵌结构沥青焦中趋于规整炭微晶含量逐渐降低,无定型炭含量逐渐增加,强度越大。当重相沥青中QI含量超过7%时,制备的镶嵌结构沥青焦中镶嵌结构总含量(细粒镶嵌、中粒镶嵌和粗粒镶嵌)超过82%,显微强度超过85%。换言之,QI含量超过7%的重相沥青是生产优质镶嵌结构沥青焦的优选原料。Abstract: Mosaic coke is a kind of special artificial carbon material, which is usually used as the raw material to produce high-quality nuclear graphite. The quality of graphite has been usually focused on the properties of mosaic cokes. In order to investigate the influence of the quinoline insoluble (QI) content of heavy-phase pitch on the micro-structure and properties of mosaic coke, 9 kinds of heavy-phase pitches with varied QI contents were used as the raw materials to produce series of mosaic cokes in this study. Optical micro-scope, scanning electronic micro-scope, X-ray diffraction, Raman spectrum and curve-fitted methods were used to judge the micro-structure of 9 kinds of mosaic cokes. Also, the micro-strength of mosaic cokes was determined. The results show that the higher content of QI in heavy-phase pitch has the mosaic structure easier to be produced during the liquid-phase carbonization process. What’s more, with the increase of QI content, the content of regular carbon microcrystals decreases, but the content of amorphous carbon and micro-strength are improved. When the QI contents in the heavy-phase are higher than 7%, the derived mosaic cokes have the total contents of mosaic structure (the sum of fine mosaic structure, medium mosaic and coarse mosaic) higher than 82% and the micro-strength higher than 85%. In other words, the heavy-phase pitch with the content of QI higher than 7% is a promised raw material to produce high-quality mosaic coke.
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图 3 镶嵌结构沥青焦中六种典型偏光结构:(a)片状结构,(b)粗纤维结构,(c)细纤维结构,(d)粗粒镶嵌结构,(e)中粒镶嵌结构,和(f)细粒镶嵌结构
Figure 3 Six kinds of typical optical structure in mosaic coke: (a) leaflet structure, (b) coarse fibrous structure, (c) fine fibrous structure, (d) coarse mosaic structure, (e) medium mosaic structure, and (f) fine mosaic structure
图 6 镶嵌结构沥青焦的SEM照片:(a)AGDP-0.3-50%-C,(b)AGDP-0.4-50%-C,(c)AGDP-0.5-50%-C,(d)AGDP-0.6-50%-C,(e)AGDP-0.7-50%-C,(f)AGDP-0.8-50%-C,(g)AGDP-0.8-60%-C,(h)AGDP-0.8-70%-C和(i)AGDP-0.8-80%-C
Figure 6 SEM graphs of mosaic cokes: (a) AGDP-0.3-50%-C, (b) AGDP-0.4-50%-C, (c) AGDP-0.5-50%-C, (d) AGDP-0.6-50%-C, (e) AGDP-0.7-50%-C, (f) AGDP-0.8-50%-C, (g) AGDP-0.8-60%-C,(h) AGDP-0.8-70%-C and (i) AGDP-0.8-80%-C
表 1 重相沥青的工业分析
Table 1 Proximate analysis of heavy-phase pitches
Sample SP /℃ TI /% QI /% CV /% AGDP-0.3-50% 78 20.31 4.99 53.84 AGDP-0.4-50% 79 22.50 7.04 55.93 AGDP-0.5-50% 80 25.67 7.06 54.77 AGDP-0.6-50% 82 24.18 7.21 55.36 AGDP-0.7-50% 82 23.72 6.13 54.00 AGDP-0.8-50% 86 25.90 6.64 58.99 AGDP-0.8-60% 120 31.55 9.70 61.00 AGDP-0.8-70% 130 37.23 14.02 64.49 AGDP-0.8-80% 156 45.21 20.22 67.82 表 2 重相沥青的元素分析
Table 2 Ultimate analysis of heavy-phase pitches
Sample C /% H /% N /% S /% O* /% AGDP-0.3-50% 92.21 4.09 1.08 0.75 1.87 AGDP-0.4-50% 93.2 3.91 0.86 0.57 1.46 AGDP-0.5-50% 93.25 3.88 0.91 0.54 1.42 AGDP-0.6-50% 93.01 3.95 1.01 0.59 1.44 AGDP-0.7-50% 93.03 4.03 1.12 0.62 1.2 AGDP-0.8-50% 92.76 4.06 1.00 1.17 1.01 AGDP-0.8-60% 91.90 3.60 1.02 0.94 2.54 AGDP-0.8-70% 91.82 3.64 1.03 0.79 2.72 AGDP-0.8-80% 91.81 3.23 0.95 0.78 3.23 *: by difference 表 3 九种镶嵌结构沥青焦的光学显微结构分布
Table 3 Distribution of optical micro-structure of 9 kinds of mosaic cokes
Sample Optical microstructure /% L Fc Ff Mc Mm Mf ∑M* AGDP-0.3-50%-C 24.00 2.50 3.50 14.50 16.00 39.50 70.00 AGDP-0.4-50%-C 15.19 0.63 0.63 23.42 19.62 40.51 83.55 AGDP-0.5-50%-C 13.94 0.00 1.92 19.71 23.08 41.35 84.14 AGDP-0.6-50%-C 12.93 0.68 4.08 14.29 25.17 42.85 82.31 AGDP-0.7-50%-C 26.71 1.43 1.43 16.86 16.43 37.14 70.43 AGDP-0.8-50%-C 25.81 1.07 2.14 18.04 11.23 41.71 70.98 AGDP-0.8-60%-C 20.12 0.61 2.44 21.95 16.47 38.41 76.83 AGDP-0.8-70%-C 11.94 1.00 0.50 20.40 21.89 44.27 86.56 AGDP-0.8-80%-C 11.41 1.04 0.34 17.41 24.83 44.97 87.21 ∑M:Mc + Mm + Mf 表 4 镶嵌结构焦中炭微晶结构参数
Table 4 Structural parameters of the microcrystalline structure in mosaic cokes
Sample γ /° π /° Aγ Aπ Ig /% Lc /nm N n AGDP-0.3-50%-C 21.61018 25.58083 743.27 3920.46 84.06 1.78 6.13 12.01 AGDP-0.4-50%-C 21.52343 25.47738 553.91 2665.36 82.79 1.68 4.76 7.25 AGDP-0.5-50%-C 22.18675 25.46421 591.04 2874.09 82.94 1.73 4.71 7.09 AGDP-0.6-50%-C 21.38190 25.44661 413.72 2140.85 83.80 1.70 4.44 6.30 AGDP-0.7-50%-C 21.85182 25.5768 433.77 2476.17 85.09 1.76 6.02 11.61 AGDP-0.8-50%-C 21.77165 25.54868 547.42 2964.72 84.41 1.77 5.75 10.57 AGDP-0.8-60%-C 21.85996 25.43312 842.34 3380.21 80.05 1.75 4.40 6.20 AGDP-0.8-70%-C 21.38620 25.38444 548.10 2816.61 83.71 1.72 3.80 4.61 AGDP-0.8-80%-C 21.31012 25.41089 517.70 2672.65 83.77 1.69 4.04 5.23 表 5 镶嵌结构焦的分峰拟合数据
Table 5 Curve-fitting data of mosaic cokes
Sample Integrate area Ratio /% ID1 ID2 ID3 ID4 IG IG/IAll ID3/IAll AGDP-0.3-50%-C 241513.7 29201.65 35629.39 41520.8 40177.34 10.35 9.18 AGDP-0.4-50%-C 541957.9 61585.15 88291.38 114910 81506.39 9.18 9.94 AGDP-0.5-50%-C 365501.6 41021.28 57707.57 88800.16 53698.82 8.85 9.51 AGDP-0.6-50%-C 274546.2 36099.4 45174.6 58339.46 39870.09 8.78 9.95 AGDP-0.7-50%-C 615535.8 63206.43 95462.96 162349.3 113947.1 10.85 9.09 AGDP-0.8-50%-C 419794.9 41435.38 64913.62 109506 69256.43 9.82 9.21 AGDP-0.8-60%-C 406857.8 50986.83 65061.17 96048.75 56192.3 8.32 9.64 AGDP-0.8-70%-C 503672.7 54928.00 78977.61 103660.2 66017.56 8.18 9.78 AGDP-0.8-80%-C 328627.9 46658.08 54453.43 81594.12 41748.72 7.55 9.85 -
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