碳纳米球/聚乙烯复合物的制备与表征

以碳纳米球为载体,经格氏试剂处理后,与TiCl4反应制成负载型Ziegler-Natta催化剂,在AlEt3存在下,催化乙烯聚合,原位制备聚乙烯(PE)/碳纳米球(CSs)复合物,催化剂活性达5.7×106gPE/(molTi·h),聚乙烯分子量为4.9×105.HRTEM和SEM结果表明,常压聚合条件下聚乙烯/CSs复合物为核-壳结构,颗粒呈圆形,直径约为1μm左右,复合物颗粒中包含碳纳米球.介电分析结果表明,由于碳纳米球的引入,复合物的介电性能相较于普通聚乙烯有明显的提高,从而提高了聚乙烯的抗静电性能,且介电常数和介电损耗都随着聚合时间的延长而降低.此外,采用WAXD,DSC和TGA表征了PE/CSs复合物的结晶性能和热性能,结果表明聚乙烯/CSs复合物具有好的结晶性能和热稳定性能.     

新型Ti-Co复合负载化催化剂制备支化聚乙烯

以反应法制备了TiCl4、乙酰丙酮改性的TiCl4和Co(acac) 2 为主催化剂 ,SiO2 MgCl2 为载体的复合负载型催化剂 (TiCl4 CH3COCH2 COCH3 Co(acac) 2 SiO2 MgCl2 ) ,以烷基铝作为助催化剂 ,以单一乙烯单体制备了支化聚乙烯 .研究了复合催化剂的组成、烷基铝种类和聚合反应温度等对聚合反应和产物结构性能的影响 .探讨了聚合反应机理 .聚合产物经IR、1 3 C NMR谱分析 ,结果表明Ti Co复合催化剂具有低聚原位共聚功能 ,可制得含有丁基、戊基、己基等各类支链结构的支化聚乙烯 .     

核壳结构Al2O3-TiO2脱硝催化剂的制备及性能研究

以核壳结构Al2 O3-TiO2为载体,V2 O5为活性组分,WO3为助催化剂,通过挤压成型制备核壳结构Al2 O3-TiO2复合载体脱硝催化剂.本文通过分析催化剂BET、XRD、抗压强度、抗硫酸盐腐蚀和脱硝反应NOx转化效率,考察核壳结构Al2 O3-TiO2复合脱硝催化剂物理化学性质.实验结果表明:核壳结构Al2 ...     

有机/无机复合载体负载复合催化剂用于乙烯聚合时有机载体的作用

采用溶胶-凝胶法,将苯乙烯-丙烯酸(P(S-co-AA))共聚物包覆在以硅胶/MgCl2为载体的TiCl3催化剂(M-1催化剂)上,负载(n-BuCp)2ZrCl2后制得TiCl3/(n-BuCp)2ZrCl2复合催化剂,研究聚合物载体P(S-co-AA)在复合催化剂乙烯聚合中的作用.前期实验结果表明有机载体P(S-c...     

结构化纳米Ziegler-Natta催化剂制备超高分子量聚乙烯

用1,4-丁二醇作为络合沉淀剂,通过再结晶活化法将晶型混乱并具有晶格缺陷的纳米级MgCl2晶粒均匀分散在硅胶表面,形成结构化纳米载体.将此载体用于负载TiCl4得到结构化纳米Ziegler-Natta催化剂.研究了醇镁比对载体形貌的影响,以及结构化纳米催化剂用于乙烯聚合的催化特性和产物特点.乙烯淤浆高压聚合结果表明结构化纳米Ziegler-Natta催化剂可用于制备超高分子量聚乙烯,并且温度对催化剂活性和聚乙烯产物的分子量都有很大的影响,在实验条件下催化剂活性可达到1261 kg PE.(molTi)-1.h-1.10-5Pa-1,超高分子量聚乙烯的黏均分子量可达到5.87×106.SEM、DSC和粒径分析等结果表明,结构化纳米催化剂制备的聚乙烯产物结晶度高,在实验考察条件下最高可达到49.5%,而且产物形貌规整,接近球形,平均粒径在68～69μm之间,利于后续的生产加工.     

无机/有机复合载体负载乙酰丙酮铁/双亚胺基吡啶催化剂及其乙烯聚合

采用溶胶-凝胶法,将苯乙烯-丙烯酸共聚物(PSA)包覆于955 Davison硅胶上得到无机/有机复合微球载体,并在2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3均相催化剂中浸渍后得到负载型双亚胺基吡啶铁催化剂.该催化剂在生产高结晶度(72%)聚乙烯的同时,还能生产一定量的α-烯烃.考察了不同膜材料以及聚合条件(不同助催化剂,压力,温度,Al/Fe摩尔比)对聚合活性以及聚合产物性能的影响,发现温度对聚合产物的α-烯烃与聚乙烯的质量比影响最大,助催化剂类型既影响催化剂的活性,也对最终产物的性质有着很大的影响.氯化镁处理的PSA作为膜材料时,负载2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3所得到聚乙烯分子量较低(Mw=11.9×104),结晶度较大(72%),熔融指数MI较高(2.35 g/10min),可作为双峰聚乙烯中的低分子量部分加以利用.     

α-二亚胺镍(Ⅱ)配合物-TiCl4复合催化剂催化乙烯原位聚合制备支化聚乙烯

制备了α-二亚胺镍()配合物[C6H5—NC(CH3)—C(CH3)N—C6H5]NiBr2(NiL)-TiCl4负载在MgCl2-SiO2载体上的复合催化剂(NiL-TiCl4/MgCl2-SiO2),以AlR3为助催化剂(不用MAO)催化乙烯聚合.研究了NiL和TiCl4负载方法、NiL/TiCl4摩尔比、助催化剂种类及聚合反应温度等对催化剂性能的影响.用IR和13CNMR表征聚合产物支化度及支链结构;用GC-MS监测聚合反应.实验结果表明,NiL-TiCl4复合催化剂具有齐聚原位共聚特性,可催化乙烯原位聚合,合成支化聚乙烯.     

Cu@Pt/MWCNTs-MnO2电催化剂的制备及电催化性能研究

通过浸渍还原法,以乙二醇作为还原剂,以H2PtCl6 6H2O作为Pt的前驱体制备了Cu@Pt/MWCNTs核壳型电催化剂;通过水热法,以KMnO4和Mn(NO3)2作为锰源制备了α-MnO2和β-MnO2,并把Cu@Pt/MWCNTs核壳型电催化剂与二氧化锰进行掺杂制得Cu@Pt/MWCNTs-MnO2复合材料.利用XRD,SEM,TEM对复合材料的结构和形貌进行表征,利用循环伏安测试曲线和阴极极化曲线等电化学测试方法对电催化剂的性能进行测试.结果表明,电催化剂中Cu@Pt纳米颗粒为核壳型,粒径为6～8 nm,MnO2的晶型为α-MnO2和β-MnO2;另外,Cu@Pt/MWCNTs-MnO2复合材料具有良好的催化性能,其中Cu@Pt/MWCNTs-β-MnO2电催化剂的电化学性能较好,具有较大的电化学活性面积,为71.1 m2 g-1,同时对MnO2促进氧还原的机理进行了初步探讨.     

XPS在有机／无机复合载体型催化剂制备中的应用

以聚丙烯接枝马来酸酐聚合物及SiO2为载体,以3-氨基三乙氧基硅烷为偶联剂,制备了有机/无机复合载体。将此载体经MAO处理后负载TiCl4制得负载型催化剂。用光电子能谱追踪了负载催化剂的制备过程,结果表明,在复合载体催化剂中存在两种可能的活性中心。     

MgCl_2/AlEt_n(OEt)_(3-n)负载单茂钛催化剂催化乙烯聚合研究

以MgCl2/AlEtn(OEt)3-n为载体,分别负载五甲基茂基三氯化钛(Cp*TiCl3)和五甲基茂基三苄氧基钛(Cp*Ti(OBz)3),得到两种负载催化剂,在较廉价的AlEt2Cl为助催化剂常压下可以高效地催化乙烯聚合.报道了载体的制备、聚合条件(不同的烷基铝助催化剂、聚合温度、铝钛摩尔比)对催化剂的聚合行为以及聚合物结构的影响.研究结果表明,两种负载催化体系对乙烯聚合具有较高的催化活性,可达105g PE/(molTi·h)数量级,所得聚乙烯的黏均分子量在105以上.经过13C-NMR和DSC分析,两种负载催化剂得到的均为线型聚乙烯.与均相催化剂相比,负载后的单茂钛催化体系的聚合反应动力学表现高效而平稳.这表明载体的微孔结构使活性中心得到了有效的分散,有效地提高了催化剂的活性,同时载体的受限空间有效抑制了聚乙烯增长链的β-H消除反应.     

给电子体在制备烯烃聚合NdCl_3载体催化剂中的作用

<正> Martin以无水稀土氯化物为载体,与磷酸三丁酯(TBP)在庚烷溶剂中反应制得LnCl_3/TBP/TiCl_4载体催化剂,其中以NdCl_3为载体的催化剂对乙烯聚合有很高活性,但对TBP的作用和载钛结构涉及较少。NdCl_3为链状晶体结构,不同于层状晶体结构的MgCl_2和TiCl_3(α和δ型)。我们对NdCl_3/EtOH/TiCl_4催化剂进行了较为详细的研究,并与MgCl_2/EtOH/TiCl_4催化剂进行比较,发现NdCl_3载体催化剂与MgCl_2载体     

Gas Phase Polymerization of Ethylene with Supported Titanium-Nickel Catalysts

A new ditransition-metal catalyst system TiCl4-NiCl2/MgCl2-SiO2/AlR3 was prepared.Gas phase polymerization of ethylene with the catalysts has been studied.The kinetic curves of gas phase polymerization showed a decline.The catalystic efficiency and polymerization reaction rates have a optimum value when Ni content of the catalysts was 12.5%(mol).The products obtained are branched polyethylene.     

Ethylene polymerization studies with supported cyclopentadienyl,arene, and allyl chromium catalysts

Highly active catalysts for low pressure ethylene polymerization are formed when chromocene, bis (benzene)- or bis (cumene)-chromium or tris- or bis (allyl)-chromium compounds are deposited on high surface area silica-alumina or silica supports. Each catalyst type shows its own unique behavior in preparation, polymerization, activity, isomerization, and response to hydrogen as a chain transfer agent. The arene chromium compounds require an acidic support (silicaalumina) or thermal aging with silica to form a highly active catalyst. At 90°C polymerization temperature arene chromium catalysts produced high molecular weight polyethylene and showed, in contrast to supported chromocene catalysts, a much lower response to hydrogen as a chain transfer agent. An increase in polymerization temperature caused a significant decrease in polymer molecular weight. Addition of cyclopentadiene to supported bis (cumene)-chromium catalyst led to a new catalyst which showed a chain transfer response to hydrogen typical of a supported chromocene catalyst. Polymerization activity with tris- or bis (allyl)-chromium appears to depend on the divalent chromium content in the catalyst. Changes in the silica dehydration temperature of supported allyl chromium catalyst have a significant effect on the resulting polymer molecular weight. High molecular weight polymers were formed with catalysts that were prepared using silica dehydration temperatures below about 400°C. Dimers, trimers, and oligomers of ethylene were usually formed with catalysts that were prepared on silica dehydrated much above 400°C. The order of activity of the different types of catalysts was chromocene/silica > chromocene/silica-alumina > bis (arene)-chromium/silica-alumina ? allyl chromium/silica.     

Effect of EtOH/MgCl(2) molar ratios on the catalytic properties of MgCl(2)-SiO(2)/TiCl(4) Ziegler-Natta catalyst for ethylene polymerization

MgCl(2)-SiO(2)/TiCl(4) Ziegler-Natta catalysts for ethylene polymerization were prepared by impregnation of MgCl(2) on SiO(2) in heptane and further treatment with TiCl(4). MgCl(2)·nEtOH adduct solutions were prepared with various EtOH/MgCl(2) molar ratios for preparation of the MgCl(2)-supported and MgCl(2)-SiO(2)-supported catalysts in order to investigate the effect on polymerization performance of both catalyst systems. The catalytic activities for ethylene polymerization decreased markedly with increased molar ratios of [EtOH]/[MgCl(2)] for the MgCl(2)-supported catalysts, while for the bi-supported catalysts, the activities only decreased slightly. The MgCl(2)-SiO(2)-supported catalyst had relatively constant activity, independent of the [EtOH]/[MgCl(2)] ratio. The lower [EtOH]/[MgCl(2)] in MgCl(2)-supported catalyst exhibited better catalytic activity. However, for the MgCl(2)-SiO(2)-supported catalyst, MgCl(2) can agglomerate on the SiO(2) surface at low [EtOH]/[MgCl(2)] thus not being not suitable for TiCl(4) loading. It was found that the optimized [EtOH]/[MgCl(2)] value for preparation of bi-supported catalysts having high activity and good spherical morphology with little agglomerated MgCl(2) was 7. Morphological studies indicated that MgCl(2)-SiO(2)-supported catalysts have good morphology with spherical shapes that retain the morphology of SiO(2). The BET measurement revealed that pore size is the key parameter dictating polymerization activity. The TGA profiles of the bi-supported catalyst also confirmed that it was more stable than the mono-supported catalyst, especially in the ethanol removal region.     

双组分茂金属催化剂催化乙烯聚合的研究

选择能形成支链的不对称桥联茂金属化合物Me2 C[(Cp) (Ind) ]ZrCl2 和非桥联的不同结构的茂金属化合物二氯二 (烯基取代环戊二烯 )锆如 ( Cp) 2 ZrCl2 ,(Cp) 2 ZrCl2 和 (Cp) 2 ZrCl2 ,以MAO为助催化剂 ,分别组成三组双组分茂金属催化剂的催化体系 ,催化乙烯聚合 .结果表明 ,两类催化剂组成的双组分茂金属催化体系催化乙烯聚合能得到支化的宽分子量分布的聚乙烯 ;聚合温度和改变两种茂金属催化剂的摩尔比对催化活性和分子量有很大影响 .因此可以利用改变双组分茂金属催化剂的摩尔比例和聚合温度来调控聚合物的分子量和分子量分布 .改变两种茂金属催化剂的摩尔比和聚合温度也能使聚合物的结晶度发生改变     

Gas Phase Polymerisation of Ethylene with Supported Titanium-Nickel Catalysts

Olefins gas phase polymerization uses generally supported titanium catalyst systems inindustrial production. The polymerization of olefins with late transition metal catalysthas recently attracted considerable interestl-2. The new catalyst family shares many ofthe advantages of metallocene catalysts in terms of activity and control of polymerproperties and, in addition, the new catalysts yield homopolymer of ethylene with veryhigh branching degrees and branching degree can be controlled.A new …     

乙烯与丙烯在负载型钛系催化剂上的共聚合行为

乙烯与α-烯烃配位共聚速率明显高于乙烯均聚速率~[1～4],其原因可归结为化学促进作用或单体扩散的影响.本文通过考察乙烯-丙烯在负载型钛系催化剂上的共聚动力学行为、催化剂-聚合物颗粒形态及改变聚合中单体的组成,以期进一步了解乙丙共聚反应的特征. 1 实验部分 1.1 催化剂及聚合 载体催化剂由无水MgCl_2、TiCl_4和EB共研磨而成,使用前用