新型铬系催化剂的制备及其载体性能

对自制硅胶和参考硅胶进行了两种方法的改性并分别制得铬系催化剂,利用热重分析仪（TG-DTA）、比表面积测定仪（BET）和扫描电子显微镜（SEM）对两种硅胶进行了分析,并对所制备的催化剂进行了聚合实验。结果表明,自制硅胶初始干燥不如参考硅胶充分。自制硅胶表观形态较优,但其破碎强度不如参考硅胶。改性剂钛的引入有利于催化活性的提高,钛的加入量一样时,通过溶胶-凝胶法改性后载体制备的催化剂活性高于传统浸渍法改性后载体制备的催化剂活性。     

硅胶负载型烯烃聚合催化剂的研究Ⅰ载体硅胶的宏观形态及热活化的影响

聚烯烃催化剂载体粒子的宏观形态在聚合过程中控制着聚合物产品粒子的宏观形态，并影响聚合催化剂的催化性能和聚合物产品性能。本文通过对催化剂载体Ｔ－１型硅胶宏观形态及其受热活化影响的研究，发现了活化过程中硅胶粒子存在着破碎和聚结现象。破碎粒子主要是粒径８０μｍ以上的大粒子，聚结粒子主要是１０μｍ以下的小粒子。还阐明了硅胶活化过程中，粒子的破碎、聚结以及硅胶粒子的流动分散性能、粒径分布、平均粒径、比表面积、孔体积、孔径的变化机制和规律     

硅胶载体镁-钛催化剂乙烯聚合性能研究

研究了硅胶载体镁-钛催化剂的制备方法以及制备过程中影响聚合性能的关键因素,研究表明采用新生态氯化镁-硅胶复合载体,用醇类化合物和氯化烷基铝进行改性的工艺路线制得的催化剂具有高的催化效率和优良的氢调能力,确定了n(醇)∶n(镁)=2.0~2.3和n(铝)∶n(镁)=1.50~1.83时催化剂具有最好的聚合性能,以及采用升温程序2煅烧活化的硅胶载体制得的催化剂颗粒形态最好。研究还表明在不改变催化剂关键配方的情况下,可以通过调整硅胶载体的煅烧活化温度和镁-钛催化剂中的钛/镁质量分数比来实现对催化剂聚合动力学行为的调控。     

用BCL-100型催化剂在Innovene S工艺装置上生产HDPE粉料的性能

研究了在Innovene S工艺装置上采用不同钛系催化剂生产的PE100级管材专用高密度聚乙烯(HDPE)粉料的颗粒形态和粒径分布。结果表明:采用国产BCL-100型催化剂生产的HDPE粉料颗粒形态好,粒径分布窄,且小于90μm的细粉质量分数仅4.1%,远少于REF型催化剂的10.3%。这是由于BCL-100型催化剂的比表面积、孔容、孔径、固体真密度和堆密度都大于REF型催化剂,所以BCL-100型催化剂粒子在HDPE分子链增长的作用下不易破碎,或破碎较少。用BCL-100型催化剂生产的HDPE粉料中细粉含量少是延长装置运行周期的主要措施之一。     

DQC-700型催化剂催化丙烯聚合

采用仪器分析和化学分析法表征了DQC-700型催化剂的组成、结构及其颗粒形态。以环己基甲基二甲氧基硅烷为外给电子体,用DQC-700型催化剂催化丙烯本体聚合,评价了预聚合温度对预聚合倍数、预聚物等规指数和预聚物粉料粒径分布的影响,研究了催化剂的聚合性能和聚丙烯粉料中的细粉含量。结果表明:DQC-700型催化剂具有较窄的粒径分布(粒径分布跨度1.0)、较大的比表面积(300 m2/g)、较高的聚合活性[45 kg/(g·h)]和立构定向性(聚丙烯等规指数98%)。     

高效气相聚乙烯催化剂的制备

探索了提高气相法聚乙烯催化剂效率的方法,其中包括选择高比表面积的硅胶载体、提高催化剂有效组分在载体上的负载量和使用三氯乙醇促进剂.结果表明:通过选择高比表面积的硅胶载体和提高催化剂有效组分的负载量可以提高催化剂效率,但这两种方法会导致催化剂的氢调性能变差;使用三氯乙醇促进剂不但可以提高催化剂的效率,而且可以改善催化剂的氢调性能.综合使用以上3种方法.可将催化剂的催化效率提高2～4倍,氢调性能优良,聚合树脂的细粉含量较低,有利于气相流化床聚乙烯生产装置的平稳运行.     

超声场对锆溶胶的影响研究

研究了超声场分布、超声时间和超声功率对锆溶胶粒径分布的影响,还表征了超声场分散溶胶所制的非担载膜的性能。实验结果表明:扩散场处理的溶胶粒径分布比驻波场处理的溶胶粒径分布略窄;提高超声功率有助于减小溶胶粒径,超声时间的增加,溶胶粒径逐渐减小,且超声处理过的溶胶稳定性得到提高;超声处理的溶胶和未超声处理的溶胶所制得的非担载膜最可几孔径均为4 nm,但前者的比表面积和孔体积略有下降。     

钛矿或钛渣对偏钛酸的影响

选取钛渣与钛矿,采用硫酸法钛白的相关制备过程,在相同条件下制备出一系列偏钛酸。对钛矿和钛渣进行XRD、SEM分析,并对所制备出的脱硝催化剂专用钛白粉原材料-偏钛酸的比表面积、粒径等做了分析。结果表明,钛渣制备的偏钛酸比钛矿制备的偏钛酸晶粒度小,团聚程度较低,比表面积小,更适合应用于制备脱硝催化剂专用的纳米二氧化钛。     

含钛复合载体对长链烷烃脱氢催化剂性能的影响

采用浸渍法、沉淀法和共沉淀法制备了含钛复合载体,并制备Pt—sn双金属催化剂;分别采用XRD、TEM、Py-IR对所制得样品的晶相和表面酸性能进行了表征。结果表明,制备方法对含钛复合载体的存在形态有一定的影响;含钛复合载体表面只有L酸位,且共沉淀法制备的含钛复合载体的酸性最弱;共沉淀法所得含钛复合载体制得的催化剂表现出最好的催化剂活性稳定性和单烯烃选择性。     

新型丙烯聚合催化剂的性能与微观结构分析

采用激光粒度分布仪,扫描电子显微镜及差示扫描量热仪,分别对新型及原丙烯聚合催化剂及其聚合物的物性进行了分析,发现新型催化剂比原催化剂颗粒粒径分布窄且分布均匀,平均粒径小,比表面积大,颗粒形态良好。小试聚合实验结果表明：新型催化剂的催化效率高,氢调敏感,聚合物等规指数容易调节并可以控制,聚合物复制了催化剂的形态,且粒径分布较窄。同时,进行了丙烯－乙烯共聚实验,从聚合物熔点及乙烯含量的测定结果可以说明：新型催化剂共聚性能优良。     

Particle size distribution of polypropylene produced in continuous polymerisation

A theoretical relationship has been developed between the particle size of polyolefin powders and that of the Ziegler-Natta catalyst from which they are derived. This has been extended to examine how the yield on catalyst and the residence time distribution in a continuous stirred tank reactor affect the particle size distribution. Experimental confirmation of these relationships has been obtained using TiCl₃ catalyst of near-spherical morphology prepared by low-temperature reduction of titanium tetrachloride with triethyl aluminium in solution.     

Population balance modeling for a continuous gas phase olefin polymerization reactor

Steady-state population balance models have been developed for a continuous flow gas phase olefin polymerization process with both uniform sized and log-normally size distributed high activity catalyst feeds. For the calculation of polymer properties such as molecular weight averages and weight fraction of comonomers in the copolymer, a multigrain solid core model was used with an assumption that intraparticle monomer mass transfer resistance is negligibly small. The multigrain solid core model was incorporated into the population balance model and the effects of feed catalyst particle size distribution and catalyst deactivation parameters on the polymer production rate, polymer particle size distribution, and polymer properties were investigated. It is observed for deactivating catalyst that the polymer particle size distribution tends to be narrower with a reduced amount of large polymer particles. For the catalyst with nonuniform site deactivation, polymer particles of different sizes exhibit different molecular weight and copolymer composition. © 1994 John Wiley & Sons, Inc.     

催化装置催化剂跑损诊断和处理

找到催化剂跑损的原因和位置,减少和避免催化剂跑损,对催化装置的良好运行十分重要。分析了催化剂粒径分布、机械强度、重金属污染能力、水热稳定性等催化剂自身原因以及原料组成变化、生产操作不当等操作原因。结果表明,回收系统问题、流化分布问题、设备固有问题、设备出现异常等设备问题是造成催化剂跑损的主要因素。通过分析新鲜催化剂、待生催化剂、再生催化剂、三旋回收催化剂等筛分组成以及油浆固含量和催化装置仪表的数值诊断出催化剂跑损位置,提出减少和避免催化剂跑损的主要措施。     

Copolymerization of ethylene/α‐olefins using bis(2‐phenylindenyl)zirconium dichloride metallocene catalyst: structural study of comonomer distribution

Catalysts have a major role in the polymerization of olefins and exert their influence in three ways: (1) polymerization behaviour, including polymerization activity and kinetics; (2) polymer particle morphology, including bulk density, particle size, particle size distribution and particle shape; and (3) polymer microstructure, including molecular weight regulation, chemical composition distribution and short‐ and long‐chain branching. By tailoring the catalyst structure, such as the creation of a bridge or introducing a substituent on the ligand, metallocene catalysts can play a major role in the achievement of desirable properties. Kinetic profiles of the metallocene catalyst used in this study showed decay‐type behaviour for copolymerization of ethylene/α‐olefins. It was observed that increasing the comonomer ratio in the feedstock affected physical properties such as reducing the melting temperature, crystallinity, density and molecular weight of the copolymers. It was also observed that the heterogeneity of the chemical composition distribution and the physical properties were enhanced as the comonomer molecular weight was increased. In particular, 2‐phenyl substitution on the indenyl ring reduced somewhat the melting point of the copolymers. In addition, the copolymer produced using bis(2‐phenylindenyl)zirconium dichloride (bis(2‐PhInd)ZrCl₂) catalyst exhibited a narrower distribution of lamellae (0.3–0.9 nm) than the polymer produced using bisindenylzirconium dichloride catalyst (0.5–3.6 nm). The results obtained indicate that the bis(2‐PhInd)ZrCl₂ catalyst showed a good comonomer incorporation ability. The heterogeneity of the chemical composition distribution and the physical properties were influenced by the type of comonomer and type of substituent in the catalyst. Copyright © 2010 Society of Chemical Industry     

钛液水解工艺对偏钛酸性能的影响

采用外加晶种常压水解法制备偏钛酸,使用激光粒度仪分析偏钛酸的粒度分布,通过沉降高度和洗涤时间判断偏钛酸的过滤性能。考察了晶种加入量、变灰点时间、钛液浓度、二次沸腾保温时间对偏钛酸粒度分布及其过滤性能的影响。结果表明：晶种加入量、钛液浓度和二次沸腾保温时间对偏钛酸性能有显著影响,晶种加入量越大、钛液浓度越低、水解速度就越快,变灰时间越短,得到的偏钛酸的粒度分布也越宽,过滤性能越差。延长二次沸腾保温时间可以使偏钛酸粒度分布更窄,粒子更均匀。     

三种催化剂对纳米纤维素尺寸分布的影响

采用激光粒度分析法测定无催化剂和添加催化剂纳米纤维素的尺寸分布,并对电子显微镜观察法与激光粒度分析法测定无催化剂纳米纤维素的尺寸分布进行了分析。结果表明添加间硝基苯磺酸钠（SMS）制备纳米纤维素尺寸分布较均一,体积数均尺寸为312．013m,所对应的尺寸分布宽度为10．8nm。电子显微镜观察法与激光粒度分析法的无催化剂纳米纤维素样品尺寸分布测定结果较接近,电子显微镜观察法表征纳米纤维素直径尺寸分布更具优势。     

TiO2的基本性质对SCR脱硝催化剂制造的影响

  针对广泛应用的蜂窝型SCR催化剂的制造过程,分析了主要原材料TiO₂的基本性质,如颗粒大小、粒度分布、形状、团聚程度、化学组成和纯度等,以及这些基本性质对催化剂制造过程中混合、挤出、干燥和煅烧等工序的影响。研究结果表明,精细程度非常高的脱硝催化剂制造过程对TiO₂的要求是：粒度分布范围较窄或单一,颗粒为球形或等轴形状,在混合工序所要求的pH值条件下团聚程度低以及TiO₂的化学组成和纯度指标高。     

水解偏钛酸粒度分布影响因素分析

以攀枝花某钛白粉厂的工业硫酸氧钛浓钛液为原料,采用外加晶种水解工艺制备水解偏钛酸,通过检测钛液水解过程中浆料透过率的变化间接检测水解过程反应速率的变化,通过分析水解过程不同时间段的偏钛酸粒度分布,确定了影响偏钛酸粒度分布的主要因素。在此基础上考察了钛液浓度、F值、铁钛比、水解晶种加量、熟化搅拌时间对偏钛酸粒度分布的影响。结果表明钛液沸腾后快速水解,再随钛液浓度降低水解速率逐渐降低,浆料粒度逐渐长大,二次沸腾20 min后,浆料的粒度分布逐渐稳定,后期保温过程对粒度分布影响不大;钛液浓度、铁钛比、F值、晶种加量和熟化期间搅拌时间均对偏钛酸粒度分布有影响,D50随着钛液浓度的增加而减小,随F值和铁钛比的增大而增加,随着晶种加量的增加而减小,随熟化期搅拌时间的延长而降低。     

Propylene polymerization using supported Ziegler–Natta catalyst systems with mixed donors

Magnesium dichloride supported titanium catalyst incorporated with varying concentration of ethylbenzoate and diisobutyl phthalate together as internal donor are synthesized. The synthesized catalysts are characterized and compared with respect to composition, phase characteristics, crystallite size, and particle morphology. Performance of catalysts containing mixed donors is compared with the conventional single donor-based catalysts. The polymerization studies of the catalysts for propylene polymerization show dependence of polymerization kinetics on relative concentration of diisobutyl phthalate and ethylbenzoate. Molecular weight characteristics of polypropylene obtained from these catalysts are studied and correlated with the nature and concentration of donors present in the catalyst. Morphology replication from catalyst precursor to polymer is observed irrespective of the nature of donor being incorporated in the synthesized catalyst. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012