共查询到19条相似文献,搜索用时 140 毫秒
1.
rac-Et(Ind)_2ZrCl_2/MAO催化丙烯/1-辛烯共聚合的研究李勇,邴娟松,谢光华(中国科学院化学研究所北京100080)关键词锆茂均相催化体系,丙烯,共聚合乙烯与长链一。烯烃共聚合制备线型低密度聚乙烯(LLDPE)和极低密度聚乙烯(VL... 相似文献
2.
研究了TiCl_4/MgCl_2-三乙基铝(TEA)高效载体催化体系下的丙烯/癸烯-1共聚及δ-TiCl_3--氯二乙基铝(DEAC)催化体系下的丙烯/辛烯-1共聚合的基本反应规律,考察了铝钛比、温度、共聚单体浓度等对共聚合的影响;对比了两种催化体系的不同,利用非均相Ziegler-Natta催化体系下共聚合的非稳态扩散动力学的观点,解释了观察到的共聚合催化效率增加,共聚物粒子增大等实验现象. 相似文献
3.
锆茂均相催化剂对乙烯/丙烯和乙烯/1-丁烯共聚合研究姚晖,肖士镜,陆宏兰(中国科学院化学研究所北京100080)关键词共聚合,乙烯,丙烯,丁烯,锆茂,甲基铝氧烷金属茂均相催化剂中过渡金属的性质,及其周围配位体的结构对催化剂性能有很大影响[1,2].金... 相似文献
4.
锆茂均相催化剂对乙烯/丙烯和乙烯/1-丁烯共聚合研究姚晖,肖士镜,陆宏兰(中国科学院化学研究所北京100080)关键词共聚合,乙烯,丙烯,丁烯,锆茂,甲基铝氧烷金属茂均相催化剂中过渡金属的性质,及其周围配位体的结构对催化剂性能有很大影响[1,2].金... 相似文献
5.
TiCl_4/SiO_2-MgCl_2载体催化剂下的乙烯/己烯-1共聚反应陈辉,张学全,黄葆同王展望,杨永然(中国科学院长春应用化学研究所长春130022)(辽阳化纤公司化工三厂辽阳)关键词乙烯,己烯,共聚,Ziegler-Natta催化剂乙烯/α-烯?.. 相似文献
6.
用微臭氧化-薄层层析法分析测定了复合催化剂AlCl_3/SbCl_3,在不同Sb/Al比、投料比、溶剂和温度等条件下的α-菠烯(M_1)/苯乙烯(M_2)共聚产物的构成,表明该复合催化剂可获得~100%共聚体,其中α-蒎烯链节含量F1可在30%~56%之间调控。在仅生成共聚体的条件下由Mayo-Lewis积分式首次测定了竞聚率。AlCl_3/SbCl_3和单独AlCl_3相比,r1增大,r2减小,r2/r1值降低了5~6倍,使不易共聚的M_1/M_2变为易于共聚,可制备M_1组分含量高的共聚体。确认该复合催化剂对M_1/M_2的优良共聚合性能在于阳离子聚合活性种的非质子和抗衡阴离子(团)的特殊结构和性质. 相似文献
7.
WO_3在TiO_2/γ-Al_2O_3和在TiO_2/SiO_2复合载体表面的分散状态和最大分散量邓存,陈巧平(宁德师范专科学校化学系,宁德352100)刘英骏(北京大学物理化学研究所,北京100871)关键词WO_3/(TiO_2/γ-Al_2O_3)催化... 相似文献
8.
研究了TiCl4/MgCl2-三乙基铝高效载体催化体系下的丙烯/癸烯-1共聚及δ-TiCl3-氯二乙基铝催化体上的丙烯/辛烯-1共聚合的基本反应规律,考察了铝钛比、温度、共聚单浓度等对共聚合的影响,对比了两种催化体系的不同,利用非均相Ziegler-Nattz催化体系下共聚合的非稳态扩散动力学的观点,解释了观察到的共聚合催化效率增加,共聚物粒子增大等实验现象。 相似文献
9.
催化-萃取光度法研究Ⅱ.H_2O_2-Co(Ⅱ)-phen-DPC/CHCl_3体系测定钴孙登明,吴峰(淮北煤炭师范学院化学系,235000)动力学分析法测定钴已有报道[1~3]。但把动力学指示反应和显色反应相结合,建立催化-萃取光度法测定钴还未见报道?.. 相似文献
10.
6,6-二苯基富烯在Cp_2TiCl_2-i-prMgBr催化下的加氢反应贺峥杰,陈寿山(南开大学元素有机化学研究所,天津,300071)关键词富烯,催化氢化,异构化在温和条件和氢气氛下,Cp2TiCl2与i-prMgBr组成的低价态钛催化体系对1,5... 相似文献
11.
The light-initiated halogenation of bicyclo[3.2.1]octene-2, its 3-phenyl and 3-bromo derivatives with N-bromosuccinimide and t-butyl hypochlorite resulted in the exclusive formation of the exo-4-halobicyclo[3.2.1]octene-2-derivatives. 相似文献
12.
Introduction Various ethylene/ α- olefin copolymers such as LLDPE,VLDPE/ ULDPE,EPR,EPDMetc.have a wide application in polymer materials science and engineering.The properties ofthose copolymers are greatly influenced by the type,content and distributions of thecomonomer branches.The effects of different kinds of chain branches,which were derivedfrom comonomerincorporationsin themain chain of the ethylene/α- olefin copolymers on theirproperties and studied by many authors,have sh… 相似文献
13.
In the presence of traces of acidic materials, Diels-Alder condensation of ethylene and cyclohexadiene-1,3 gives, besides the expected bicyclo[2,2,2]octene-2, the isomeric bicyclo[3,2,1] octene-2; the latter is formed through acid-catalysed rearrangement. Its structure was proved among other things by stepwise oxidative degradation to cyclopentane- cis-1,3-dicarboxylic acid. Competitive halogenations of bicyclo[2,2,2]octane and cyclohexane showed that the methylene groups in the latter are somewhat more reactive. Reactivity ratios decreased at increasing temperatures. The reactivity of the bridgehead positions in bicyclo-octane towards hydrogen removal is appreciably larger than that of the methylene groups, in contrast to the situation in bicyclo[2,2,1]-heptane. This is probably due to the greater flexibility of the bicyclo-octane skeleton permitting a near-planar configuration at the bridgehead. Some of the differences between the bicyclo[2,2,2]octane, bicyclo[2,2,1]heptane and cyclohexane systems are briefly discussed. 相似文献
14.
The solution copolymerization of ethylene (1) with octene-1 (2) in Isopar E using constrained geometry catalyst system, [C 5Me 4(SiMe 2N tBu)]TiMe 2 (CGC-Ti)/tris(pentafluorophenyl)boron (TPFPB)/modified methylaluminoxane (MMAO), has been carried out in a high-temperature, high-pressure continuous stirred-tank reactor (CSTR) at 140°C, 500 psig and with a mean residence time of 4 min. A series of copolymer samples with octene-1 content up to 0.337 mole fraction were synthesized and characterized. The estimated reactivity ratios were r1 = 7.90 and r2 = 0.099. The CGC-Ti showed a higher ability to incorporate high α-olefins than other metallocene catalysts investigated in the literature due to its open structure. The presence of octene-1 lowered the catalyst activity, particularly at octene-1 levels higher than 0.45 mole fraction. Octene-1 was also found to reduce the molecular weight of polymer and broaden the molecular weight distributions. The triad distributions were measured by 13C-NMR. A minor penultimate effect was observed. The penultimate octene-1 unit appeared to slow down monomer insertion rates. A comparison of the propagation rate of octene-1 with the incorporation rate of macromonomer in the homopolymerization of ethylene suggests that the addition of macromonomer is effectively instantaneous after it is generated with diffusion to or from the active center reaction volume playing a minor role. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2949–2957, 1999 相似文献
15.
When (Z)-1-tridecen-6-ynyl propanoate was treated with a titanium(II) alkoxide reagent, Ti(O-i-Pr)4/2i-PrMgCl, a novel tandem cyclization took place to give (1RS,2RS,3SR)-3-ethyl-4-hexyl-4-bicyclo[3.3.0]octene-2,3-diol virtually as a single stereoisomer after aqueous workup. The generality of this cyclization was also shown. Similarly, (Z)-3-butyl-1-tridecen-6-ynyl propanoate afforded (1RS,2RS,3SR,8SR)-8-butyl-3-ethyl-4-hexyl-4-bicyclo[3.3.0]octene-2,3-diol with a diastereoselectivity of >95:5, demonstrating the simultaneous construction of a total of four consecutive stereogenic centers in the product and with virtually complete diastereoselectivity. 相似文献
16.
研究了水/有机两相体系中TPPTS(磺化三苯基膦)氧化为OTPPTS(氧化的TPPTS)对Rh/TPPTS催化烯烃氢甲酰化反应的影响. 结果表明,在己烯-1、辛烯-1和十二烯-1氢甲酰化反应中,当n(OTPPTS)/n(TPPTS)<1时,对催化剂体系性能的影响较小,但当n(OTPPTS)/n(TPPTS)>1时,将引起催化剂体系的活性、选择性和稳定性下降; 如果保持体系中TPPTS的含量一定,使n(TPPTS)/n(Rh)≥18,当n(OTPPTS)/n(Rh)=20时,则对催化剂体系性能的影响不明显. 这说明生成的OTPPTS不是铑催化剂的毒物. TPPTS氧化为OTPPTS致使铑催化剂的活性和生成醛的选择性下降, 是由于TPPTS浓度的降低导致n(TPPTS)/n(Rh)值过低,使催化循环中各活性物种的平衡发生变化及铑配合物的稳定性变差所造成的结果. 相似文献
17.
In this paper, the upconversion luminescent properties of Gd2O3:Er3+,Yb3+ nanowires as a function of Yb concentration and excitation power were studied under 978-nm excitation. The results indicated that the relative intensity of the red emission (4F(9/2)-4I(15/2)) increased with increasing the Yb3+ concentration, while that of the green emission (4S(3/2)/2H(11/2)-4I(15/2)) decreased. As a function of excitation power in ln-ln plot, the green emission of 4S(3/2)-4I(15/2) yielded a slope of approximately 2, while the red emission of 4F(9/2)-4I(15/2) yielded a slope of approximately 1. Moreover, the slope decreased with increasing the Yb3+ concentration. This was well explained by the expanded theory of competition between linear decay and upconversion processes for the depletion of the intermediate excited states. As the excitation power density was high enough, the emission intensity of upconversion decreased due to thermal quenching. The thermal effect caused by the exposure of the 978-nm laser was studied according to the intensity ratio of 2H(11/2)-4I(15/2) to 4S(3/2)-4I(15/2). The practical sample temperature at the exposed spot as a function of excitation power and Yb3+ concentration was deduced. The result indicated that at the irradiated spot (0.5 x 0.5 mm2) the practical temperature considerably increased. 相似文献
19.
The mechanism of isobutyraldehyde-octene-2 cooxidation at 20°C has been investigated. The ratio of cis to trans epoxides in the reaction products shows that, at aldehyde concentrations lower than 1.0 M, the epoxide is formed mainly by a radical route. The difference in the Δ H of formation of cis and trans epoxides is around 0.8 kcal/mole at 20°. The isobutyraldehyde involved in the radical epoxidation chain has been found almost quantitatively to be isopropylhydroperoxide, which is formed through the decarboxylation of i-PrCO 2· radicals, addition of oxygen, and abstraction of hydrogen atoms from the aldehyde. A rate constant of about 14 M ?1 sec ?1 at 20° has been determined for the latter reaction. The chain length for the cooxdination reaction decreases from 75 to 20 as the isobutyraldehyde concentration goes from 1.0 to 0.3 M. The termination step seems to involve mainly the interaction of two i-PrO 2 · radicals. The cooxidation of octene-2 with pivalaldehyde follows a similar mechanism, but the chain length is about ten times higher under the same experimental conditions. 相似文献
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