可纺石油基中间相沥青制备及测试分析

中间相沥青是由重质芳烃类物质(煤焦油沥青、石油沥青和纯芳烃类物质及其混合物等)在中温液相炭化热处理过程中形成的一种具有较大区域范围内晶体光学各向异性的液晶态物质。本文以催化裂化油浆为原料制备中间相沥青,考察不同原料特性对中间相沥青的影响,研究了中间相沥青的形成机理。通过工艺参数的优化,所制备的石油基中间相沥青可以达到以下性能:中间相含量在95%～100%之间,软化点为250～290℃时,结构呈现广域流线型结构,制备的碳纤维具有极高的导热率。     

中间相沥青的调制及其大直径炭纤维制备

以萘沥青为原料,分别采用常压聚合、加压聚合以及甲苯可溶组分加压聚合3种方式调制中间相沥青,并对制备的3种中间相沥青进行熔融纺丝、氧化稳定化和炭化处理制备大直径(约20μm)炭纤维,再利用相关测试仪器对制得的不同中间相沥青及其炭纤维进行分析和表征。结果表明:相同热处理条件下,加压聚合制备的中间相沥青较常压聚合的沥青液晶相转化程度高,分子取向优异,以其为原料制备的大直径炭纤维拉伸强度为840 MPa,明显高于常压聚合沥青所制炭纤维的拉伸强度(540 MPa)。萘沥青经甲苯抽提后灰分从790×10~(-6)降至180×10~(-6),以其可溶组分加压聚合制备的中间相沥青光学织构取向较好,所制大直径炭纤维的拉伸强度可达950 MPa。     

煤直接液化沥青制备中间相沥青炭纤维的研究北大核心

中间相沥青基炭纤维的性能直接取决于纺丝用中间相沥青,煤直接液化沥青因其饱和烃含量高,氢碳比高,高温融变性好,硫含量低等优点成为制备纺丝用中间相沥青的优良前驱体。本文以煤直接液化沥青为原料,研究不同热缩聚工艺对中间相沥青组成和结构的影响,通过考察其偏光织构、软化点、喹啉不溶物含量、黏温曲线和纺丝时长等指标综合评价可纺性。采用高低温结合多段聚合工艺制得具有大融并体结构、可纺性优良的中间相沥青,并进一步制得具有理想微观形貌的纤维,其拉伸强度为2.03 GPa,拉伸模量达到581 GPa。     

两种精制沥青热改质研究

以热过滤制备的精制沥青和萃取沉降制备的精制沥青为原料,采用常压-减压法进行热改质研究,对热改质产物进行了光学结构、红外光谱表征及软化点、TI、QI等指标测定。研究结果表明,以热过滤制备的精制沥青热转化生成中间相的速度要大于由萃取沉降制备的精制沥青热转化生成中间相的速度。两种精制沥青都是制备中间相沥青的较好原料。     

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。     

煤沥青基中间相沥青的制备研究

以纯化的煤焦油沥青为原料,考察了热聚合温度和恒温时间对中间相沥青的收率、光学显微形态、软化点和族组成的影响.结果表明:反应温度在420℃,恒温5 h时得到了软化点为312℃的流线体型中间相沥青,其收率为79.1%;热聚合反应在相对较低的温度400℃,反应时间为10 h时形成了软化点为305℃、收率为81.4%的优质广域型可纺性中间相沥青.对该原料煤沥青而言,通过控制热聚合反应温度和恒温时间可以达到制备优质中间相的目的.     

2种煤沥青的中间相热聚合行为研究

以中温煤沥青(MTCP)和改质煤沥青(MCP)为原料，采用热聚合反应方法，在相同的反应时间下，研究不同反应温度下2种煤沥青的中间相热聚合行为。采用软化点仪、偏光显微镜、X射线粉末衍射仪(XRD)以及激光共焦拉曼光谱仪(Raman)对中间相沥青表征和分析。结果表明，2种煤沥青在相同工艺条件下呈现出相似的中间相聚合行为。偏光显微镜照片说明2种煤沥青聚合所得到的中间相类型均为镶嵌结构。XRD与Raman分析表明随着聚合温度的升高，中间相沥青内部芳香片层分子的取向性更好，排列更为规整。MTCP经过430℃、8 h聚合，可制备软化点为319℃的中间相含量高于80%的中间相沥青；MCP经过420℃、8 h聚合，可制备软化点316℃,中间相含量高于80%的中间相沥青。     

三种不同原料中间相沥青的性质表征

为更深入地理解不同原料制备的中间相沥青的性质差别,从挥发分、饱和度、分子量分布、有序度的角度研究了以萘、煤沥青、精制煤液化沥青（DCLR）为原料的3种中间相沥青,分析手段包括偏光显微镜、元素分析、TGA、红外光谱（FTIR）、MALDI-TOF MS、XRD、拉曼。结果表明：萘系中间相沥青分子量最高且分布窄,挥发分低,饱和基团含量高,分子柔性大,平面性和规整性较差,分子堆砌紧密度较低,有序度较差,因此具有较低的软化点和广域流线型光学组织结构;煤系中间相沥青分子量较高,分布最宽,挥发分高,饱和度低,烷基侧链少,分子刚性和平面性较大,易堆积成紧密结构,因此具有较高的软化点,流动性差,较难形成流线型光学组织结构;DCLR系中间相沥青分子量低且分布窄,挥发分较高,含有一定量的饱和基团,分子具有一定的韧性,分子刚性和规整性较好,有序度高,因此流动性较差,软化点较高。     

催化裂化油浆溶剂抽提及其中间相沥青

考察了FCC油浆及其在不同温度、不同剂油比条件下抽出油的组成和性质。确定了最佳抽提条件为50℃，剂油比为2：1。计算所得选择性表明糠醛是分离FCC油浆的有效溶剂。抽出油形成的中间相沥青，具有良好的可溶性，显现广域流线型大融并体，分子排列规整，具有较佳的流动性，是一种易石墨化炭。抽余油形成的中间相沥青，显示粗镶嵌结构，可溶性较差，难以制取上佳炭材料，但可回收作催化裂化原料。     

低温煤焦油沥青性质分析及应用初探

以低温煤焦油沥青为原料,分离其轻组分得到重相沥青,通过对2种沥青的组成、性质及炭化后焦样指标、微观结构对比分析,研究2种低温煤焦油沥青的性质差异,探索适合低温焦油沥青深加工利用的应用途径。结果表明:低温煤焦油沥青及重相沥青主要由饱和分、芳香分、胶质、沥青质组成,它们的含量变化,制约着原料的热反应过程;低温煤焦油沥青含有大量的饱和分,经炭化后所得焦样镜下出现大片、小片及镶嵌结构,均一性较差,此种沥青不适合直接用来制备高性能的炭素材料;低温煤焦油重相沥青中饱和分含量明显降低,胶质、沥青质含量升高,炭化后焦样的镜下结构以细镶嵌为主,有少量小片,结构均一且无单一取向性,各向同性度高,可以尝试用来制备各向同性焦炭。     

Influence of organic sulfur compounds and metals on mesophase formation

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.     

Structural study of cokes using optical microscopy and X-ray diffraction

Cokes exhibiting a range of optical texture from isotropie to anisotropic domains > 60 μm diameter were examined by X-ray diffraction. The variation of an optical texture index (OTI) with crystallite height and interlayer spacing was studied. The OTI varies little with the X-ray parameters for cokes whose optical texture is larger than medium-grained (1.5–5.0 μm) mosaic anisotropy. For cokes of smaller optical texture there is a sharp decrease in crystallite height and an increase in interlayer spacing. These results are discussed in terms of fluid mesophase removing defects in cokes of optical texture of size of coarsegrained mosaics and larger. The cokes of smaller optical texture are formed from less fluid mesophase which does not coalesce. Defects therefore remain in this anisotropic carbon of the coke so reducing crystallographic order.     

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.     

纺丝温度对中间相沥青炭纤维结构性能的影响

以萘催化合成中间相沥青(MP-1)和热缩聚法制备中间相沥青(MP-2)两种中间相沥青为原料,对其进行簇组成分析、偏光显微镜观察及红外光谱分析,研究其组成及结构.采用实验室气压式单孔纺丝装置在不同温度下对两种中间相沥青进行熔融纺丝,探讨纺丝温度对炭纤维结构及性能的影响.研究表明:MP-1低温获得无规结构,高温出现中心放射状边缘洋葱皮混合结构;MP-2随纺丝温度升高依次出现无规结构、准洋葱皮结构和洋葱皮结构.中间相沥青原料的性质影响着纤维截面结构随纺丝温度变化的规律.     

热聚合温度对煤液化沥青制备中间相沥青的影响

为制备优质的中间相沥青,以煤液化沥青为原料,在不同热聚合温度下制备中间相沥青,采用偏光显微镜、红外光谱仪、XRD、热分析等测试仪器对所得中间相沥青进行分析和表征。结果表明,温度对中间相沥青的收率、形貌和结构影响显著。随着温度升高,中间相沥青的收率降至86.2%,H含量降至3.96%,S含量有所下降,残炭率增大;中间相小球体的尺寸增大,逐渐出现融并现象,最终形成广域型中间相;煤液化沥青中的稠环芳烃、芳香烃的含量明显增加,烷烃成分则明显减少;煤液化沥青中的无定型区含量减少,分子的排列与取向性变好。选择低的热缩聚温度(410~420℃),适当延长反应时间有利于反应方向的控制,从而达到制备优质中间相的目的。     

A two-stage preparation of mesophase pitch from the vacuum residue of FCC decant oil

The preparation of mesophase pitch as a precursor for the high-performance carbon fiber from a vacuum residue of FCC-decant oil (FCC-DOVR) was studied, applying a two-stage heat treatment to improve the pitch yield as well as its liquid crystal properties. The present two-stage preparation consisted of the pressurized heat treatment (1–5 MP) of the first stage at 430–480°C and the successive heat treatment under 13–260 Pa at 430°C. Such a two-stage preparation increased the yield of the spinnable mesophase pitch of 100% domain texture with lower softening point to 45% from 22% by the single-stage one from the same feedstock. Spinning properties of the mesophase pitch were excellent to allow smooth spinning for longer than 15 min and random orientation of mesogen molecules in the tranverse section of the fiber perpendicular to the fiber axis. The chemistry of the two-stage preparation for the higher yield and better properties as the fiber precursor is briefly discussed.     

Needle coke formation derived from co-carbonization of ethylene tar pitch and polystyrene

Ethylene tar pitch was co-carbonized with waste polystyrene to prepare needle coke. The modified properties of mesophase, which were greatly improved due to increasing naphthenic and other alkyl content, availed the formation of needle coke with high quality. The coefficient of thermal expansion value was decreased from 3.2 × 10⁻⁶/°C to 0.3 × 10⁻⁶/°C and the optical texture of the coke was changed from coarse mosaic texture to flow domain of high uniaxial orientation after adding waste polystyrene into ethylene tar pitch. The low viscosity of the mesophase pitches favored the development of mesophase and highly uniaxial arrangement. The increase in alkyl group content greatly improved characteristics of the needle coke.