Polymerization of 1,3-butadiene over metal oxides-supported nickel chloride catalysts

Summary Polymerization of 1,3-butadiene was conducted by two series of catalysts: nickel ion exchanged Y-zeolite and metal oxides-supported nickel chloride. For these polymerizations, a plausible active species was proposed.     

Polymerization of propylene with highly active MgCl2-supported TiCl3 catalyst

Summary The MgCl₂ supported TiCl₃ catalyst was prepared by grinding the mixture of TiCl₃·3Py and MgCl₂ in a ball mill. The catalyst was treated either i.vac. at 50–200°C or with alkylaluminum halides to remove the residual pyridine, and propylene polymerization was conducted at 65°C using the resulting catalysts combined with triethylaluminum. The catalyst treated with diethylaluminum chloride showed an extremely high activity for the polymerization.     

Polymerization of propylene by highly active catalysts synthesized with Mg(OEt)2/benzoyl chloride/TiCl4

Summary Active centers have been studied in the polymerization of propylene using highly active Mg(OEt)₂/Benzoyl chloride/TiCl₄ catalysts activated with AlEt₃. The method for the measurement of active centers is based on the inhibiting effect of CO on polymerization. The activity of the present catalysts, which is higher than that of TiCl₃ or MgCl₂-supported catalyst, is mainly due to the higher concentration of active centers by one order of magnitude. In order to investigate the stability of active centers during polymerization the number of active centers are compared at various polymerization times.     

Polymerization of propylene with TiCl3–AlEt2Cl–trilauryltrithiophosphite catalyst

AlEt₃Cl was modified with TLTTP (trilauryltrithiophosphite) in the catalyst system consisting of TiCl₃ and AlEt₂Cl. The effects of TLTTP on the polymerization of propylene were studied in comparison with those of alkyl homologues of TLTTP. The catalytic behavior of the TiCl₃–AlEt₂Cl-TLTTP catalyst system in the polymerization of propylene was also studied in comparison with that of the TiCl₃–AlEt₂Cl catalyst system. In the study of the effect of various alkylthiophosphites added, it is found that the bulkiness of the alkyl group affects the rate of propylene polymerization and the stereoregularity of the resultant polymers. The TiCl₃–AlEt₂Cl–TLTTP catalyst system gave different catalytic behavior in the propylene polymerization from that of the unmodified conventional catalyst system (TiCl₃–AlEt₂Cl). These effects of TLTTP were considered to be due to the bulkiness of the alkyl groups attached to the phosphorous atom and the higher reactivity to TiCl₃ of the modified AlEt₂Cl than of the unmodified AlEt₂Cl.     

Polymerization of propylene over titanium exchanged Y-zeolite

Summary It was found that isotactic polymerization of propylene took place over titanium ion-exchanged Y-zeolite without organometallic compounds. The results obtained have led to the conclusions that Ti⁴⁺ species as well as Ti³⁺ species are active for the polymerization and that neither Ti-alkyl bonds nor Cl ligands are necessarily essential for polymerization of propylene.     

TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅱ.聚合条件及聚合动力学

使用以球磨法制备的 SiO2负载 TiCl4催化剂进行丁二烯溶液聚合,考察了聚合条件对催化效率的影响以及在 20～ 60℃下的聚合动力学。确定了适宜的聚合条件：以加氢汽油为溶剂, Al/Ti摩尔比为 20, Ti/Bd摩尔比为 2× 10－ 4, 50℃聚合 10 h以上。溶液聚合动力学研究结果表明,本体系在低转化率下为稳态聚合,其稳态聚合速率方程为 Rp=kpf[Ti]0[Bd],聚合的表观活化能为 11.4 kJ/mol。     

Polymerization of propylene oxide by using double metal cyanide catalysts and the application to polyurethane elastomer

Polymerizations of propylene oxide have been carried out by using double metal cyanide (DMC) catalysts based on Zn₃[Co(CN)₆]₂. By controlling the type and the amount of complexing agent during preparation of catalyst the catalytic activity, initiation time, and the unsaturation level in polyether polyols could be tuned. Various catalysts prepared by changing the complexing and co-complexing agents were characterized by x-ray photoelectron spectroscopy, infrared spectroscopy, and X-ray powder diffraction. Highly active catalyst prepared by choosing a polytetramethylene ether glycol as a co-complexing agent resulted in polyoxypropylenes (POP) with low very low unsaturation level (0.003-0.006 meq/g) and with narrow molecular weight distribution (MWD=1.02-1.04). The active sites of DMC-catalyzed polymerization of propylene oxide have both cationic and coordinative characters. ¹³C NMR analysis showed that the polyols have a random distribution of the configurational sequences and head-to-tail regiosequence, even if the amount of [rr] triad of polyol produced by DMC catalyst was larger than that of polyol by conventional KOH catalyst. The distortionless enhancement by polarization transfer analysis showed that there exist regioirregular sequences as well. The stress-strain curves of methylene diisocyanate/1,4-butanediol cured POP-based polyurethane elastomers showed that the unsaturation content contained in POP showed a dramatic effect on the mechanical properties.     

Preparation of soluble TiCl3 catalysts by reduction of TiCl4 with Grignard reagents and their use for copolymerization of ethylene with propylene

Summary Preparations of soluble TiCl₃ catalysts by reduction of TiCl₄ with some types of Grignard reagents were carried out in halogenated hydrocarbon solvents by using appropriate ethers as donor. The soluble TiCl₃·MgX₂·ether complex catalysts and triisobutylaluminum as co-catalyst showed high activities for the copolymerization of ethylene with propylene. It was first found that the soluble TiCl₃·MgX₂·ether complex catalysts enhance the activities for the copolymerizations in the same manner as solid titanium catalysts supported on MgCl₂ which show high activities for homopolymerizations of olefin monomers. The copolymers obtained possessed low crystallinities. Also, the copolymers seem to contain microblock sequences and have outstandingly high tensile strength and elongation at break compared to copolymers by the conventional VOCl₃/Al(Et)_1.5Cl_1.5 catalyst system.     

Propane dehydrogenation to propylene over Pt-based catalysts

Propane catalytic dehydrogenation to propylene was investigated over novel platinum-based catalysts, and the BET, H₂-chemisorption, H₂-TPR, H₂-TPD, C₃H₆-TPD and O₂-pulse techniques were used for catalyst characterization in this paper. The results showed that the addition of Zn and Ce promoters into Pt-based catalyst could remarkably improve the performances of dehydrogenation. Highly propylene selectivity, about 99%, was obtained in the dehydrogenation reaction. This improvement in catalytic performances could be attributed to the strong surface interactions, which modified the surface properties of the active platinum metal and the support, and further improved the catalytic performance of Pt-based catalyst.     

Studies on highly active coordination catalysts for polymerization of α-olefins: 3. Polymerization of propylene with MgCl2/TiCl4/AlEt3 or MgCl2/PhCOOC2H5/TiCl4/AlEt3 systems

Activity and stereospecificity of the $\text{MgCl}{}_2\text{TiCl}{}_4$ catalyst in the polymerization of propylene follow curves showing maxima with grinding time of the MgCl₂ support. Using MgCl₂/PhCOOC₂H₅/TiCl₄ catalysts, no decrease in activity and stereospecificity was observed presumably because of complex formation between MgCl₂ support and ethyl benzoate.     

Particle control of Ziegler–Natta catalysts based on TiCl3 for propylene polymerization. Effect of prepolymerization

Prepolymerizations employing an extremely high stereospecific and high active catalyst based on TiCl₃ modified by di-n-butyl ether (DBE) were carried out with different monomers (styrene, propylene, hexene-1, cyclopentadiene). The influence of prepolymerization on the morphology of polypropylene obtained with TiCl₃ catalyst was investigated. The catalyst was synthesized by TiCl₄ reduction in toluene solution with A1Et₃·DBE complex. The polymer morphology was evaluated through optical and scanning electron microscopies and polymer bulk density and particle size distribution. © 1994 John Wiley & Sons, Inc.     

Polymerization of propylene in liquid monomer using state-of-the-art high-performance titanium-magnesium catalysts

A comparative study of propylene polymerization in liquid monomer is performed under laboratory conditions using the IK-8-21 Ti-Mg catalyst designed at the Boreskov Institute of Catalysis and imported industrial catalysts (conditionally labeled TMC-1, -2, and -3). The activity and stereospecificity of the catalysts are estimated along with properties of the resulting polypropylene (granular composition and physicomechanical characteristics). It is shown that the IK-8-21 catalyst is not inferior to imported counterparts in terms of catalytic properties in the synthesis of polypropylene. The polypropylene powder formed on IK-8-21 is homogeneous and has good morphology. The physicomechanical characteristics of polypropylene synthesized on the domestic IK-8-21 catalyst are similar to those for polypropylene prepared with the imported TMK-1 catalyst.     

Copolymerization of ethylene with propylene over the thermally-reduced γ-Al2O3-supported TiCl4 catalyst

Summary Copolymerization of ethylene with propylene was conducted over the thermally-reduced -Al₂O₃-supported TiCl₄ catalyst both in the absence or presence of AlEt₃ (or AlEt₂Cl). It was found that the structure of the polymer drastically changed from a random copolymer to polyethylene with an increase in the concentration of AlEt₃. A plausible mechanism was proposed for the copolymerization.     

双金属氰化物络合物催化环氧丙烷聚合

双金属氰化物经各合物的催化活笥随着有机配体中醚键数目的增多而增强,其催化环氧丙 聚合反应具有生聚合特性,反应体系中的小分子多元醇在聚合中起链转移剂的作用。     

锌基催化剂制备及其催化合成碳酸丙烯酯

通过尿素沉淀法制备了以锌基为主要活性组分的不同的复合型氧化物催化剂,考察了尿素与1,2-丙二醇（PG）合成碳酸丙烯酯（PC）反应的催化性能。用XRD,SEM,BET,CO2-TPD等技术对催化剂进行了表征。结果表明,催化剂的强碱性位数量可能是影响催化活性的关键因素, 在此基础上推出碱催化机理：较强的碱强度有利于降低中间产物羟丙基氨基甲酸酯（HPC）转化为PC的活化能。在反应温度170℃,反应时间1h, PG/尿素摩尔比1.5, 0.6g催化剂(尿素质量的2%),反应压力300mmHg的条件下, PC收率高达99.8%.锌/镁1:4催化剂经过五次再生,PC收率降低了2.2%。     

TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅲ.聚合物的结构与性能

用以球磨法制备的TiCl4/SiO2负载型催化剂进行丁二烯溶液聚合,考察了聚合条件对聚合物溶解性及结构的影响,测试了聚合物的基本力学性能.结果表明,Ti/Bd、聚合温度、溶剂类型对聚合物的溶解性影响较大.随着聚合温度升高,聚合物的反式-1,4-结构摩尔分数增加,顺式-1,4-结构摩尔分数降低.聚合物生胶具有较高的强度和邵尔A型硬度,但扯断伸长率低,其硫化胶具有较好的耐磨性和回弹性.     

Active centers of TiCl3 catalysts for propene polymerization

Summary Publications reporting numbers of active centers in TiCl₃ propylene polymerization catalysts are very contradictory. Experimental data from the beginning of the sixties are reevaluated by the author. It is concluded that TiCl₃-catalysts from the Hoechst type (and probably from the Stauffer AA-type) have, after an initial period of polymerization, numbers of active centers in the range of percentage of total TiCl₃. This value increases with temperature. By cooling during polymerization some metal polymer bonds, probably active centers, disappear.Conversion versus time and molecular weight versus conversion for propene polymerization     

Polymerization of N-substituted 2-propynamides with transition metal catalysts

Summary Polymerization of N-substituted 2-propynamides proceeded in the presence of Pd(II) catalysts such as [Pd(CH₃CN)₄](BF₄)₂, PdCl₂(PhCN)₂-n-BuLi, and PdCl₂(nbd)-n-BuLi. The molecular weights of the obtained polymers ranged 8,500 to 14,000, depending on the catalysts. From the ¹H NMR spectra, these polymers were found to have alternating double bonds in the main chain. Received: 25 December 2000/Revised version: 17 January 2001/Accepted: 19 January 2001