芳香类重质油基针状焦的制备及表征

针状焦作为一种应用广泛的人造炭素材料,是制备超高功率石墨电极和锂离子电池负极用石墨的重要原料。原料的基础物性对针状焦的品质影响极大,从而进一步影响石墨材料的性质。为进一步考察芳香族重质油制备高品质针状焦的可行性,分别以混合油(MO)和乙烯渣油馏分油(EPO)为原料,利用延迟焦化装置进行公斤级试验。分别以FTIR和TGA解析重质油的分子结构以及热解特性,从光学组织结构、表面形貌、晶体结构、微晶分布形式以及导电性能五个方面分析针状焦性质。研究结果表明：MO和EPO的芳香性指数(I_ar)分别为0.592 7和0.569 4,支链化指数(CH₃/CH₂)为0.351 6和0.228 3,得到的针状焦MO-Coke和EPO-Coke中纤维状结构含量分别为47.68%和57.40%。两种针状焦MO-Coke和EPO-Coke表面光滑且呈类石墨片层结构,微晶堆垛高度分别为2.73 nm和3.50 nm,理想石墨微晶含量达到10.58%和16.43%,电阻率仅为489μΩ·m和471μΩ·m。换句话说,芳香族重质油MO和EPO是制备高品...     

延迟焦化工艺新技术探索

我国大部分原油具有重质渣油多、沥青质、残炭量少的特点,采用延迟焦化工艺加工重质渣油,可以得到高达78%的馏分油收率。所得馏出油中,汽油馏分较少,柴油与汽油的产量比值可达2.3左右,经加氢精制后,产品质量可达到规格要求,比较适合我国市场对中间馏分日益增长的需求状况。     

石油系新型炭材料的研发现状和发展趋势

主要介绍了几种石油系新型炭材料 ,如中间相沥青、中间相沥青炭微球、碳纤维及其复合材料、针状焦、活性炭的研发现状和发展趋势 ,并对独山子石化公司生产的几种石油沥青、石油渣油进行了组成分析比较 ,对石油系渣油制备新型炭材料的可能性进行了分析     

管弹式焦化器作为延迟焦化器的模拟装置

采用在熔融锡浴中的管弹式焦化器作为延迟焦化器的模拟装置,在加压和快速加热条件下对石油渣油进行了碳化试验。这样碳化得到了一种块状焦,这种块状焦的宏观外表和微观外表、热膨胀系数(CTE)和堆密度和由同一原料在延迟焦化器中生产的针状焦具有类似的性质。研究了碳化条件对生成焦性质的影响。     

石油渣油和沥青作为针状焦原料的评价

在加压和快速加热条件下,在臂弹式焦化器中碳化了几种石油渣油,来评价它们作为针状焦原料的性能。用光学显微镜检查、测量热膨胀系数(CTE)和堆密度等方法鉴定了生成焦的质量,以便找出原料结构特性和生成焦的质量之间的关系。     

石墨烯晶种法制备有序针状焦及电化学性研究

实验以石墨烯(Graphene, GE)为晶种, 精制煤沥青为原料, 通过程序控温, 对如何制备高含量的各向异性中间相条件进行了优化, 并将其用于制备半焦和针状焦研究。中间相和半焦的组织结构采用偏光显微镜进行了观察和分析, 针状焦用X射线衍射仪(XRD)和扫描电子显微镜(SEM)进行了观察, 并通过电化学工作站对半焦进行了电化学性质分析, 用循环伏安法对石墨微晶结构的有序性进行了分析。结果表明: 石墨烯的加入, 明显促进了中间相小球的形成, 显著提高了所制针状焦结构的有序性和电子的传输能力。其中, 当石墨烯加入量为原料的0.2wt%时, 得到的中间相小球数量最多且大小均匀, 半焦结构的纤维流域状结构成为其主要的显微组织。在相同的情况下, 同未加石墨烯相比较, 石墨烯的存在使制备的针状焦石墨化度提高了200%; 电荷迁移电阻减少65.3%。     

乳液法制备中间相炭微球的研究

为制备高性能中间相炭微球(MesocarbonMicrobeads,简称MCMB),选用三种不同中间相含量的石油渣油沥青为原料(中间相体积含量:PP185%,PP290%,PP3100%),采用乳液法制备中间相沥青微球(MesophasePitchMi crobeads,简称MPMB),再经预氧化和炭化处理,制得圆整度好、收率高、球径分布窄的中间相炭微球。利用扫描电子显微镜(SEM)考察了MPMB的微观形貌,同时还利用激光粒度分析仪测定了MPMB的粒度分布。研究了乳液法制备MPMB的影响因素,研究结果表明:(1)耐高温硅油适宜作为乳液法的导热分散介质;(2)不同中间相含量的沥青制备微球时有其适宜的处理温度和时间(PP1:320℃,30min;PP2:330℃,30min;PP3:355℃,30min),且制得的微球收率(收率:PP1相似文献   

不同温度下加磁制备针状焦的结构与性能研究

以除去喹啉不溶物的中温煤沥青为原料,通过在不同温度下对原料体系进行磁化制备了针状焦。采用扫描电镜(SEM)、X射线衍射(XRD)表征了产物针状焦的结构特征;采用循环伏安法(CV)测试了产物针状焦的电化学性能。结构分析表明,不同温度下加磁制备的针状焦有明显的区别,其中在420℃加磁制备的针状焦具有较规则的微观结构,并且石墨化度得到大大提升;电化学测试表明,在420℃加磁制备的针状焦具有较高的电容量和比电容值,并具有良好的充放电可逆性。     

前驱体对炭泡沫孔结构的影响

分别以煤沥青、石油中间相沥青和AR沥青为前驱体制备炭泡沫材料。采用GPC测定前驱体分子量,SEM观察所制炭泡沫的孔结构,光学显微镜测量所制炭泡沫的孔径及其分布。结果发现,由于煤焦油沥青不含中间相,且QI含量较高,导致在实验条件下不能直接制备出合格的炭泡沫。以石油中间相沥青和AR沥青为原料均能制备出具有分布均匀开孔结构,且微观各向异性的炭泡沫。由AR沥青制备的炭泡沫呈现平均孔径较小(212μm)、孔壁较薄、孔径分布较窄(180μm~300μm)、开孔率较高、以及韧带排列较规整等特点,表明低QI含量、低分子量且分布较窄的前驱体有利于发泡。     

由高缩合度芳烃制备中间相

一、液晶相基础由于煤系和石油系的渣油具有合适的C/H比,它们是生产高级炭材料(例如,高功率电极用针状焦或炭纤维)的优良原料。沥青类残渣要获得石墨晶体结构,必须经过许多层次的有序化。在300—500℃左右,沥青类物质能排列成中间相状态,液晶相就是在此阶段构     

聚乙二醇法测定超滤膜截留率的不确定度评定

截留率和切割分子量是表征超滤膜截留性能的主要技术参数。以聚乙二醇-20000为标准物质,建立截留率测试结果的不确定度评定数学模型,分析不确定度来源,评定超滤膜截留率测试结果的不确定度。结果表明,PEG-20000的多分散系数(Mw/Mn)为1.005,优于标准中对截留测试标准物质的分子量分布系数小于1.8的要求,GPC谱图呈现单峰形式,符合PEG结构明确、分子量分布窄的特点,完全满足测试需要,标准测试曲线线性好、相关系数R2大于0.999;通过重复性实验,测定了超滤膜对PEG-20000的截留率为93.04%,对该结果进行了A类和B类不确定度评定,当包含因子k=2、置信水平为95%时,扩展不确定度为2.90%。     

聚丙烯纤维料树脂对无纺布性能的影响研究

目的 研究聚丙烯原料对无纺布的力学和加工性能的影响规律，从而制备出力学性能高、纺丝性能好的无纺布。方法 以不同熔融指数的聚丙烯粉料为基础树脂，使用不同的过氧化物与其进行共混熔融挤出造粒，然后采用气相色谱、高温凝胶渗透色谱、拉伸等测试手段对样品的基础物性、分子结构、气味、VOC、残留物和无纺布的力学性能及加工稳定性等方面进行表征与分析。结果 以熔融指数8 g/10 min(GB/T 3682.1—2018)的粉料为基础树脂，加入少量的3,6,9-三甲基-1,4,7-三过氧壬烷，挤出造粒制备出的4号树脂原料样品。该样品具有高的熔体流动性(MFR为35~40 g/10 min)、窄的分子量分布(3~5)、低灰分和鱼眼数、低气味、低残留的过氧化物等性能，从而制成拉伸强度高、纺丝效率高且加工稳定的无纺布成品。结论 基础聚丙烯树脂的分子量设计、原料的配方体系、工艺路线都对无纺布制品的力学性能和可纺性产生重要影响。     

Rheological Behaviour for Polymer Melts and Concentrated Solutions Part Ⅲ: A New Multiple Entanglement Model to Predict the Dependence of Linear Viscoelastic Function (η_0, Ψ_(10)~0,η_(ext)~0) on the Ranges of Primary Molecular Weights and the

It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer chain and the sequence distribution of constituent chains in entanglement spacings. A unified quantity for the three combing factors is the average constrained dimensional number of constituent chains in the long entanglement spacings (v). A new relation of v to the primary molecular weight and the number of testing polymers were derived from the multiple entanglement and reptation model, and a new method for determining v was proposed. The dependences of linear viscoelastic functions on the primary molecular weight and its distribution were derived by the statistical method. When Mn=6Me to 18 Me, the values of (v) can range from 3.33 to 3.70. Their values are in a good agreement with the experiment data, and it can slightjy vary with the different species of polymers and the different ranges of molecular weight of polymers     

Morphologies of coke deposited on surfaces of pure Ni and Fe-Cr-Ni-Mn alloys during pyrolysis of propane

Morphologies of coke deposited on pure Ni and Fe-Cr-Ni-Mn alloy surfaces during pyrolysis of propane at 750–1000°C have been investigated in detail. It is found that surface scales developed initially on pure Ni and Fe-Cr-Ni-Mn alloy surfaces have no catalytic effect on deposition of filamentary coke. But metal or alloy substrates under cracked scales strongly catalyze nucleation and growth of filamentary coke along the cracks. Ni is more efficient to catalyze the growth of filamentary coke than Fe-Cr-Ni-Mn alloys. The structure of oxide scales has marked influence on distribution and size of filamentary coke deposited on alloy surfaces. Coking morphology is closely dependent of coking temperature and time. Either increasing coking temperature or prolonging coking time results in coking morphology changes from filamentary to spherical. Both dissolution/precipitation mechanism and direct nucleation and growth mechanism may make a contribution to the development of graphitic film coke.     

On the lateral habits of polymer single crystals

Single crystals of trans-1, 4-polyisoprene (TPIP) have been grown from dilute solutions in amyl acetate, n-heptane and n-butanol/n-heptane mixtures. Two samples of different molecular weights, and molecular-weight distribution have been used to demonstrate the effect of these molecular parameters on the shape of single crystals. The experiments suggested that crystallization of narrowly distributed polymer chains, irrespective of the molecular weight of the crystallizing species, will produce a hexagonal morphology. This narrow distribution of chains during crystallization can be achieved by starting with a sample of low polydispersity or using a solvent/non-solvent mixture for crystallization. If the chain-size distribution is not controlled, then at later stages of growth the heterogeneous mixture of chains will create a curvature on the {110} faces and produce oval-shaped lamellar platelets. Further, the crystal habits in the present work were found to be related to the solvent, molecular weight and molecular-weight distribution, rather than to the crystallization temperature.     

延迟焦化装置对掺炼催化油浆的影响

为解决炼油厂催化装置油浆作为燃料油外销效益低的问题,中国石化股份公司沧州分公司在延迟焦化装置进行了掺炼催化油浆的试验探索,催化油浆在焦化原料中以不同的的掺炼比例进行了试验。本文就延迟焦化装置掺炼油浆的反应机理和对焦化的产品分布、产品质量、装置能耗及对焦化设备的影响进行了总结分析。     

Change in the Molecular Weight Distribution of Gelatin by a High Pressure Slurry Jet

Abstract

Physical and photographic properties of gelatin depend on the molecular weight distribution of the gelatin, which it is important to control. We controlled the molecular weight distribution of gelatin by pressurizing the sample gelatin solution and jetting it at high velocity from a nozzle to a collision plate. II was found that this method teas effective in controlling the molecular weight distribution of gelatin and in preparing a gelatin which contains mainly ± and β components and few high and low molecular weight components.     

Preparative Chromatography and Analysis of Molecular Weight Fractions of Gelatin

Preparative scale gel filtration chromatography has been used to isolate different molecular weight fractions of gelatin for subsequent chemical analysis. The broad molecular weight distribution of gelatin was fractionated into four regions corresponding to high molecular weight, beta, alpha and low molecular weight material. Characterization of the isolated fractions included molecular weight distribution, amino acid composition, total active sulphur measured by cysleic acid analysis after oxidative hydrolysis and analysis of the pyridinoline crosslinks. A limed bovine ossein gelatin was characterized by these ttxhniques.     

The cold-drawing of high density polyethylene

The cold-drawing of high density polyethylene has been studied over a wide range of temperatures and strain rates for a series of samples of very different molecular weight distribution. A natural draw-ratio was observed which was almost independent of temperature and strain rate, but was sensitive to the weight average molecular weight. A good correlation was observed between the Young's modulus of the drawn mono-filaments and the natural draw-ratio, and it is proposed that the Young's modulus is primarily related to molecular orientation rather than to interlamellar ties.     

Effects of molecular weights on the absorption, distribution and urinary excretion of intraperitoneally administrated carboxymethyl chitosan in rats

Carboxymethyl chitosan (CM-chitosan) is one of water-soluble derivatives of chitosan. Numerous studies have been focused on its applications as pharmaceutical excipient, bioactive reagent and nontoxic drug carrier. Like other polysaccharides, CM-chitosan is inhomogenous in molecular weight. Originations and preparation procedures considerably influence its molecular weight and molecular weight distributions. Understanding the molecular weight related biological behaviour of this inhomogenous glycopolymer in vivo were crucial for the quality control and clinical applications of chitosan and chitosan based medical devices. In this study, we investigated the effects of molecular weights on the absorption, distribution, degradation and urinary excretion of the fluorescein isothiocyanate-labeled CM-chitosan in rats. The results indicated that molecular weight significantly influenced the uptake of CM-chitosan from the lumen of abdomen and blood vessels to peripheral tissues, the distribution of this chemical and urinary excretion after intraperitoneal administration. These findings provided an important reference for the clinical applications of this versatile derivative of chitosan as postsurgical and other biomedical materials and important clues for the exploitation of CM-chitosan based drug targeting and delivery systems.