Metallocene-catalyzed ethene/styrene co- and terpolymerization with olefinic termonomers

Ethene was co- and terpolymerized with 1-octene and styrene using the methylalumoxane (MAO) activated halfsandwich metallocene Me₂Si(Me₄Cp)(N-t.-butyl)TiCl₂(Cp = cyclopentadienyl, Me = methyl) as catalyst. At temperatures of 40 and 60°C styrene concentration was varied in order to investigate the influence of the comonomers. Despite decreasing the overall activity with respect to ethene/1-octene copolymerization, polymerization activity was found to exibit a relative maximum with increasing styrene concentration. An explanation is given taking two different comonomer effects into account. Low styrene concentration promoted higher 1-octene incorporation compared to ethene/1-octene copolymerization but significantly lowered the molecular weight of the terpolymers. With constant ethene and 1-octene concentration it was possible to produce ethene/1-octene/styrene terpolymers with styrene content varying from 0 to 25 mol % and 1-octene content varying from 8 to 21 mol %. All terpolymers were amorphous. With constant ethene content it was found possible to vary their glass transition temperature with 1-octene/styrene molar ratio incorporated in the terpolymer. ¹³C-NMR spectroscopic microstructure analysis showed that no styrene/1-octene sequences were found in the terpolymer backbone. Furthermore terpolymerizations were conducted successfully incorporating norbornene, 1,5-hexadiene and propene as monomers in terpolymertization with ethene and styrene. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2549–2560, 1997     

Co- and terpolymerizations of ethene and α-olefins with metallocenes

The suitability of the (n-butCp)₂ZrCl₂/methylaluminoxane (MAO) catalyst system for the copolymerization of ethene with propene, hexene, and hexadecene was studied and Ind₂ZrCl₂/MAO was tested as a catalyst for ethene/propene and ethene/hexene copolymerizations. The synergistic effect of longer α-olefin on propene incorporation in ethene/propene/hexene and ethene/propene/hexadecene terpolymerizations was investigated with Et(Ind)₂ZrCl₂MAO and (n-butCp)₂ZrCl₂/MAO catalyst systems. The molar masses, molar mass distributions, melting points, and densities of the products were measured. The incorporation of comonomer in the chain was further studied by segregation fractionation techniques (SFT), by differential scanning calorimetry (DSC), studying the β relaxations by dynamic mechanical analysis (DMA) and by studying the microstructure of some copolymers by ¹³C-NMR. In this study (n-butCp)₂ZrCl₂ and Ind₂ZrCl₂ exhibited equal response in copolymerization of ethene and propene and both catalysts were more active towards propene than longer α-olefins. A nearly identical incorporation of propene in the chain was found for the two catalysts when a higher propene feed was used. A lower hexene feed gave a more homogeneous comonomer distribution curve than a higher hexene feed and also showed the presence of branching. In terpolymerizations catalyzed with (n-butCp)₂ZrCl₂, the hexadecene concentrations of the ethene/propene/hexadecene terpolymers were always very low, and only traces of hexene were detected in ethene/propene/hexene terpolymers. With hexene no clear synergistic effect on the propene incorporation in the terpolymer was detected and with hexadecene the effect of the longer α-olefin was even slightly negative. With an Et(Ind)₂ZrCl₂/MAO catalyst system both hexene and hexadecene were incorporated in the chain in the terpolymerizations. © 1997 John Wiley & Sons, Inc.     

Defined synthesis of copolymers using metallocene catalysis

The copolymerization of propene with small amounts of ethene, catalyzed by tetrahydroindenyl zirconocenes such as [En(H₄Ind)₂]ZrCl₂ or [Me₂Si(H₄Ind)₂]ZrCl₂ and MAO in liquid propene produces polymers with much higher activities and molecular weights than the homopolymerization of propene. The normal bisindenyl complexes doesn't present such differences. The investigation of the microstructure shows for the tetrahydroindenyl catalyst that after a 2,1-insertion of a propene unit the system is in a sleeping state and can be activated when an ethene unit is inserted. In this case these catalysts become faster than the ansa bis-indenyl catalysts. An active catalyst for the copolymerization of ethene and norbornene is the more temperature stable [Me₃PhPen(Flu)]ZrCl₂. This catalyst produces atactic copolymers with high molecular weights of over 900 000 g/mol at 30°C and 38 mol% of norbornene content.     

Palladium‐Promoted Carbon Monoxide/Ethylene/Styrene Terpolymerization Reaction: Throwing Light on the Different Reactivity of the Two Alkenes

The catalytic behavior of dicationic bis‐chelated Pd^II complexes, [Pd(N? N)₂][PF₆]₂, in the CO/ethylene/styrene terpolymerization reaction is studied in detail. The bidentate N‐donor ligands were chosen among 2,2′‐bipyridine ( 1 ), 1,10‐phenanthroline ( 3 ), their symmetrically substituted derivatives 2, 4 , and 5 , and 3‐alkyl‐substituted 1,10‐phenanthrolines 6 – 10 . The effect of several parameters (like temperature, CO/ethylene pressure, styrene content, reaction time) was investigated and related to the productivity of the catalytic system, to the relative content of the two olefins in the polymeric chains, and to the molecular mass of the synthesized polyketones. The presence of 1,4‐benzoquinone was necessary to reach productivities as high as 16 kg of terpolymer (TP) per gram of Pd. ¹³C‐NMR spectroscopy was useful to characterize the distribution of the two repetitive units along the polymer chain. Terpolymers with prevailingly isolated CO/styrene units in CO/ethylene blocks as well as terpolymers with CO/styrene and CO/ethylene blocks were obtained by varying the reaction conditions. Detailed MALDI‐TOF‐MS analysis was performed on the CO/ethylene/styrene terpolymers for the first time, and it allowed us to characterize the end groups of the terpolymer chains. The presence of different chain end groups was found to be related to the initial amount of the two alkenes, thus suggesting that different reactions are involved in the initiation and termination steps of the terpolymerization catalytic cycle.     

Course of the terpolymerization of ethylene,propylene, and dicyclopentadiene. II. Two-step addition of dicyclopentadiene

Terpolymerizations of ethylene, propylene, and dicyclopentadiene were carried out in which the dicyclopentadiene was added to the reaction system in two equal portions at the beginning and midpoint of each run, while the monoolefins were added continuously. In the resultant elastomers, unsaturation remains much more constant throughout the course of the polymerization than for terpolymers obtained when all dicyclopentadiene is added at the start of the reaction. Yield and molecular weight of the terpolymers produced by either technique are quite comparable, however. With VCl₄ catalyst (with Al₂Et₃Cl₃ cocatalyst) in heptane solvent, the two-step addition of the diene gave terpolymers with little gel, in contrast to the high gel in terpolymers formed with the single initial addition of the diene. This system also produced terpolymer with the highest final unsaturation and molecular weight. Catalysts of VCl₄, VOCl₃, or V(C₅H₇O₂)₃ in benzene gave terpolymers of moderate unsaturations and molecular weights.     

Smog chamber study of H2O2 formation in ethene?NOx and propene?NOx mixtures

Hydrogen peroxide formation in the photooxidation of CO? NO_x, ethene? NO_x, and propene? NO_x mixtures has been determined in the TVA 31 cubic meter smog chamber under the following conditions: [NO_x] ca. 22–46 ppb; ethene = 0.22–1.1 ppm, [propene] = 0.12–0.97 ppm; [H₂O] ca. 8 × 10^?3 ppm. Ethene, propene, NO, NO_x, PAN, HCHO, and CH₃CHO were also monitored. Computer modeling was performed using the gas phase ethene and propene mechanism of the Regional Acid Deposition Model. There is good agreement between the model predicted and observed H₂O₂ concentrations. However, to successfully model all the propene? NO_x experimental results, organic nitrate formation from the reaction of peroxy radicals with NO must be included in the mechanism.     

Role of CO2 in dehydrogenation of propane over CrOX/SiO2 catalyst with low Cr content

When ethene alone was contacted with silica supported cobalt catalyst (Co/SiO₂), ethene homologation took place with considerable activity. Moreover, the propene metathesis reaction was suppressed ca. 1/6 fold as much as in the case using MoO_X/SiO₂ catalyst. The possibility of selective homologation with a lower activity for metathesis was suggested for the cobalt-based catalyst system.     

Polymerization of olefins with a novel dinuclear ansa-zirconocene catalyst having a biphenyl bridge

Both the rac- and meso-dinuclear ansa-zirconocene catalysts (μ-C₁₂H₈{[SiPh(Ind)₂]ZrCl₂}₂) were prepared by a coupling reaction between 2 equiv of diindenylphenylchlorosilane (rac- and meso-isomers) and 1 equiv of p-dilithiobiphenyl in diethyl ether at −80°C, followed by a successive reaction with ZrCl₄ · 2THF in THF at −78°C. Polymerizations of ethene and propene were conducted in a 1 dm³ high-pressure glass reactor equipped with a mechanical stirrer at 60, 80, 100, 120, and 150°C using methylalumoxane (MAO) as cocatalyst and toluene or decahydronaphthalene as the solvent. Copolymerization of ethene and 1-octene was also checked in brief. For ethene polymerization, the meso-catalyst was found to be more active, which displayed an extremely high activity to give linear polyethene with a high molecular weight and a narrow molar mass distribution (MMD). The apparent activity increased monotonously with rising polymerization temperature from 60°C up to 150°C, indicating that the active species are stable even at a high temperature. On the other hand, both the rac- and meso-catalysts showed very poor activities for propene polymerization. However, copolymerization of ethene and 1-octene proceeded at a high speed. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2269–2274, 1998     

Propene polymerization using homogeneous MAO-activated metallocene catalysts: Me2Si(Benz[e]Indenyl)2ZrCl2/MAO vs. Me2Si(2-Me-Benz[e]Indenyl)2ZrCl2/MAO

Propene was polymerized at 40°C and 2-bar propene in toluene using methylalumoxane (MAO) activated rac-Me₂Si(Benz[e]Indenyl)₂ZrCl₂ ( BI ) and rac-Me₂Si(2-Me-Benz[e]Indenyl)₂ZrCl₂ ( MBI ). Catalyst BI /MAO polymerizes propene with high activity to afford low molecular weight polypropylene, whereas MBI /MAO is less active and produces high molecular weight polypropylene. Variation of reaction conditions such as propene concentration, temperature, concentration of catalyst components, and addition of hydrogen reveals that the lower molecular weight polypropylene produced with BI /MAO results from chain transfer to propene monomer following a 2,1-insertion. A large fraction of both metallocene catalyst systems is deactivated upon 2,1-insertion. Such dormant sites can be reactivated by H₂-addition, which affords active metallocene hydrides. This effect of H₂-addition is reflected by a decreasing content of head-to-head enchainment and the formation of polypropylene with n-butyl end groups. Both catalysts show a strong dependence of activity on propene concentration that indicates a formal reaction order of 1.7 with respect to propene. MBI /MAO shows a much higher dependence of the activity on temperature than BI /MAO. At elevated temperatures, MBI /MAO polymerizes propene faster than BI /MAO. © 1995 John Wiley & Sons, Inc.     

SiGeAl-ITQ-13和SiAl(B)-ITQ-13分子筛的合成及其甲醇转化制烃催化性能

采用直接水热合成和后合成两种方法制备Al-ITQ-13分子筛,用于催化甲醇转化制备烃类化合物。采用XRD、²⁷Al MAS NMR、NH₃-TPD、Py-FTIR和SEM等技术对所合成样品进行了表征。结果表明,两种方法制备的Al-ITQ-13结晶度都较高,且晶体形貌为薄片。与ZSM-5相比,Al-ITQ-13在甲醇转化反应中显示出较高的丙烯选择性、较高的丙烯/乙烯产物比以及较好的催化稳定性。同时,由于后合成所得到的SiAl（B）-ITQ-13强酸量减少,其催化性能优于直接合成的SiGeAl-ITQ-13。     

Random propene/4‐methyl‐1‐pentene copolymers synthesized with C2 symmetric highly isospecific metallocenes

Propene (P)/4‐methyl‐1‐pentene (Y) copolymers in a wide range of composition were prepared with isospecific single center catalysts, rac‐Et(IndH₄)₂ZrCl₂ ( EBTHI ), rac‐Me₂Si(2‐Me‐BenzInd)₂ZrCl₂ ( MBI ), and rac‐CH₂(3‐^tBuInd)₂ZrCl₂ ( TBI ). ¹³C NMR analysis of copolymers and statistical elaboration of microstructural data at triad level were performed. Unprecedented and surprising results are here reported. Random P/Y copolymers were prepared with the most isospecific catalyst, TBI , that is known to prepare ethene/propene and ethene/4‐methyl‐1‐pentene copolymers with long homosequences of both comonomers, whereas longer homosequences of both comonomers were observed in copolymers from the less enantioselective metallocenes EBTHI and MBI . These findings, which are against what is acknowledged in the field, can pave the way for the preparation on a large scale of random propene‐based copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2575–2585     

Slight Structural Disorder in Bithiophene-based Random Terpolymers with Improved Power Conversion Efficiency for Polymer Solar Cells

A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol%and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor(D-A) type copolymer PTB7-Th(P1). All polymers showed similar molecular weight with number-average molecular weight(Mn) and weight-average molecular weight(Mw) in the range of(59-74) and(93-114) kg·mol~(-1), respectively, to ensure a fair comparison on the structure-property relationships.Compared with the control copolymer PTB7-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from400 nm to 650 nm in both solution and film as well as in polymer/PC71 BM blends. From grazing incident wide-angle X-ray diffraction(GIWAXS), compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced(100) lamellar stacking and slightly weakened(010) π-π stacking for the polymers as well as slightly reduced PC71 BM aggregation in polymer/PC71 BM blends. However, the measured hole mobility for terpolymers((1.20-3.73) × 104-cm2·V-1·s~(-1)) was evaluated to be comparable or even higher than 1.35 × 10~(-4) cm~2·V~(-1)·s-1 of the alternative copolymer. Enhanced average power conversion efficiency(PCE) from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.     

Stopped‐flow polymerizations of ethene and propene in the presence of the catalyst system rac‐Me2Si(2‐methyl‐4‐phenyl‐1‐indenyl)2ZrCl2/methylaluminoxane

The kinetics of ethene and propene polymerization at 20–60°C in the presence of the homogeneous catalyst system rac‐Me₂Si(2‐methyl‐4‐phenyl‐1‐indenyl)₂ZrCl₂/methylaluminoxane was investigated by means of stopped‐flow techniques. The specific rate of chain propagation, measured at the very short reaction times typical of this method, turned out to be ≈10² times higher for ethene than for propene; this suggests that diffusion limitations through the poly(ethylene) precipitating at longer reaction times may be responsible for the fact that the two monomers polymerize instead at comparable rates under “standard” conditions. It was also found that the concentration of active sites is significantly lower than the analytical Zr concentration.     

COPOLYMERIZATION OF ETHYLENE AND PROPYLENE WITH CpCH2CH2CH=CH2)2MCl2(M=Zr,Hf)AND Cp2ZrCl2 CATALYSTS

(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst, ~(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.     

Kinetics of oxidation of lower olefins with Fe(III) aqua ions in the presence of the Pd/ZrO2/SO4 precatalyst in a chloride-free system

The kinetics of oxidation of ethene, propene, and 1-butene with Fe(III) aqua ions to the corresponding carbonyl compounds in the presence of the 1% Pd/ZrO₂/SO₄ precatalyst in aqueous perchloric acid at 40–80°C was studied. The oxidation rate increases in the order C₂H₄ < C₄H₈ < C₃H₆ and with increasing catalyst weight and in the acid and Fe(III) concentrations; it is independent of the olefin pressure. The ethene oxidation rate is described by the Michaelis-Menten equation. In the case of 1-butene, the reaction is accompanied by migration of the double bond with the formation of 2-butene.     

Random ethene/propene copolymerization from a catalyst system based on a “constrained geometry” half‐sandwich complex

Ethene/propene copolymerizations were performed in solution with a single centre catalyst system composed of a “constrained geometry” half‐sandwich organometallic complex {η¹: η⁵‐[(tert‐butylamido)dimethylsilyl](2,3,4,5‐tetramethyl‐1‐cyclopentadienyl)}titanium dichloride, and methylaluminoxane. The statistical treatment of polymerization data allowed to determine the reactivity ratios for ethene and propene: r_E = 1.35 ± 0.09, r_P = 0.82 ± 0.05, r_Er_P = 1.10 ± 0.14. This catalyst system promotes an almost random distribution of ethene and propene and gives rise to values of r_P and r_E very similar to each other.     

Higher α‐olefins carbonylation in aqueous media by Pd(II) catalysts modified with substituted diphosphine ligands: Aqueous polyketone latices with high solid contents and molecular weights

Water‐soluble palladium complexes cis‐[Pd(L)(OAc)₂] ( 1–8 ) (L represents a diphosphine ligands of the general formula CH₂(CH₂PR₂)₂, where for a : R ? (CH₂)₆OH; b–g : R ? (CH₂)_nP(O)(OEt)₂, n = 2–6 and n = 8; h : R ? (CH₂)₃NH₂) have been employed, after activation with a large excess of HBF₄, for emulsion polymerization of alkenes (propene, butene, and their equimolar mixtures) with carbon monoxide. Aliphatic polyketone lattices with a high solid content (21%), high molecular weight (6.3 × 10⁴ g mol^?1), and narrow polydispersities (M_w/M_n ≈ 2) were isolated. The catalytic activity of the dicationic palladium (II) based catalysts, C1–C8 is highly dependent on the length of the alkyl chain of the ligand. Catalyst 3 proved to be highly active for propene/CO copolymers, whereas 6 is active for butene/CO and propene/CO‐butene/CO systems. The presence of methyl β‐cyclodextrin, as a phase‐transfer agent, and undecenoic acid, as an emulsifier, increase the molar mass and the stability of the polyketones and finally the activity of the catalyst. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6715–6725, 2009     

Charakterisierung und katalytische Aktivität von Ni2+-ausgetauschten X- und Y-Zeolithen. II. Die Reduzierbarkeit des Ni2+ durch niedere Olefine und die Dimerisierungsaktivität der Ni2+-ausgetauschten Zeolithe

Characterization and Catalytic Activity of Ni²⁺ -X and -Y Zeolites. II. Reducibility of Ni²⁺ by Low Olefines and the Dimerization Activity of the Ni²⁺ -Zeolites The reducibility of Ni²⁺ in X and Y zeolites by hydrogen, but-1-ene, propene, and ethene is compared. The degree of reduction was determined after isothermal reduction and reoxidation by the TPR method. At 673 K on X zeolites the reducibility decreases in the order: H₂ > but-1-ene, propene > ethene. On Y zeolites an inversion takes place: but-1-ene, propene > H₂, ethene. The mechanism of reduction by olefins should be determined by an intermediate splitting off of a hydride ion as a reducing species. Such a mechanism explains the higher degree of reduction in the more acid Y zeolites. Assuming low valent nickel as an active center in ethen dimerization the induction period results from the reduction of Ni²⁺ ions.     

Isomer-specific product detection of CN radical reactions with ethene and propene by tunable VUV photoionization mass spectrometry

Product detection studies of CN reactions with ethene and propene are conducted at room temperature (4 Torr, 533.3 Pa) using multiplexed time-resolved mass spectrometry with tunable synchrotron photoionization. Photoionization efficiency curves, i.e., the ion signal as a function of photon energy, are used to determine the products and distinguish isomers. Both reactions proceed predominantly via CN addition to the π orbital of the olefin. For CN + ethene, cyanoethene (C₂H₃CN) is detected as the sole product in agreement with recent studies on this reaction. Multiple products are identified for the CN + propene reaction with 75(±15)% of the detected products in the form of cyanoethene from a CH₃ elimination channel and 25(±15)% forming different isomers of C₄H₅N via H elimination. The C₄H₅N comprises 57(±15)% 1-cyanopropene, 43(±15)% 2-cyanopropene and <15% 3-cyanopropene. No evidence of direct H abstraction or indirect HCN formation is detected for either reaction. The results have relevance to the molecular weight growth chemistry on Saturn's largest moon Titan, where the formation of small unsaturated nitriles are proposed to be key steps in the early chemical stages of haze formation.     

不同硅铝比Al-ITQ-13分子筛的甲醇制丙烯反应催化性能

采用晶种法直接合成了硅铝比(SiO_2/Al_2O_3物质的量比)为137、224和309的三种Al-ITQ-13分子筛,并采用粉末X射线衍射(XRD)、扫描电镜(SEM)、N_2吸附-脱附、固体核磁共振(MAS NMR)和NH_3-程序升温脱附(NH_3-TPD)等分析方法对不同硅铝比分子筛进行了表征,并在固定床微型反应评价装置上,考察了硅铝比对甲醇转化制丙烯反应性能的影响。结果表明,不同硅铝比Al-ITQ-13分子筛呈现出相似的织构性质,酸量及酸强度随着硅铝比的升高逐渐下降。硅铝比对甲醇转化反应的产物分布存在较大的影响;随着硅铝比的升高,氢转移反应和芳构化反应活性降低,使得乙烯选择性下降,而丙烯和丁烯的选择性升高。硅铝比由137提高到309,丙烯的选择性(质量分数)由46.04%增加到55.52%,而丙烯/乙烯比由3.39提高到6.57。