Ethylene Polymerization by Phenyl Sulfide Bridged Dinuclear Titanocene Complex/MAO

2011 ◽  
Vol 181-182 ◽  
pp. 804-808
Author(s):  
Yu Jing Nie ◽  
Ming Yang
Keyword(s):  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Polymerization Temperature ◽  
Phenyl Sulfide ◽  
Highly Active ◽  
Concentration Time ◽  
Cyclopentadienyl Ligand ◽  
Broad Molecular Weight Distribution

The phenyl sulfide bridged metallocene complex [(C5H5)Cl2TiC5H4CH2(C6H4-p)]2S has been synthesized by treating the dilithium salts of the phenyl sulfide bridged cyclopentadienyl ligand with two equivalents of C5H5TiCl3 and characterized by 1HMNR and elemental analysis. After activation with methylaluminoxane (MAO), the complex was highly active catalysts for homogeneous ethylene polymerization in toluene. The influence of the molar ratio [MAO]/[Cat], the catalyst concentration, time and temperature have been studied systematically. The highest catalytic activity of 1 is up to 8.30×105 g PE/mol•Cat•h. Rising the polymerization temperature decreases the catalytic activity for 1. High temperature gel permeation chromatography (HT-GPC) proves the production of polyethylene with a broad molecular weight distribution (MWD), which is reached 10.11.

Ethylene Polymerization by Thioether Bridged Dinuclear Titanocene Complex

2011 ◽  
Vol 213 ◽  
pp. 354-357 ◽  
Author(s):  
Yu Jing Nie ◽  
Ming Yang
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Polymerization Temperature ◽  
High Concentration ◽  
Highly Active ◽  
Cyclopentadienyl Ligand ◽  
Broad Molecular Weight Distribution

The thioether bridged metallocene complex [(C5H5)Cl2TiC5H4CH2CH2]2S has been synthesized by treating the dilithium salts of the thioether bridged cyclopentadienyl ligand with two equivalents of C5H5TiCl3 and characterized by 1HMNR and elemental analysis. After activation with methylaluminoxane (MAO), the complex was highly active catalysts for homogeneous ethylene polymerization in toluene. The influence of the molar ratio [MAO]/[Cat], the catalyst concentration, time and temperature have been studied systematically. The catalytic activity of 1 is 3.63×105 g PE/mol•Cat•h. Rising the polymerization temperature decreases the catalytic activity for 1. A high concentration of the catalysts drops the catalytic activity as well as the molecular weight of polyethylene for the complex. High temperature gel permeation chromatography (HT-GPC) proves the production of polyethylene with a broad molecular weight distribution (MWD).

Ethylene Polymerization by Phenyl Sulfide Bridged Dinuclear Zirconocene Complex/MAO

2011 ◽  
Vol 181-182 ◽  
pp. 809-813
Author(s):  
Yu Jing Nie ◽  
Ming Yang
Keyword(s):  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Catalyst Concentration ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Phenyl Sulfide ◽  
Concentration Time ◽  
Cyclopentadienyl Ligand ◽  
Broad Molecular Weight Distribution ◽  
Higher Temperature

The phenyl sulfide bridged Zirconocene complex [(C5H5)Cl2ZrC5H4CH2(C6H4-p)]2S has been synthesized by treating the dilithium salts of the phenyl sulfide bridged cyclopentadienyl ligand with two equivalents of C5H5ZrCl3(DME) and characterized by 1HMNR and elemental analysis. Homogenous ethylene polymerization by this complex has been conducted systematically in the presence of methylaluminoxane (MAO). The influence of the molar ratio [MAO]/[Cat], the catalyst concentration, time and temperature have been studied in detail. The highest catalytic activity of 1 is up to 13.78×105 g PE/mol•Cat•h. Higher temperature is favorable for increasing the catalytic activity for 1. High temperature gel permeation chromatography (HT-GPC) proves the production of polyethylene with a broad molecular weight distribution (MWD), which is reached 6.02.

Ethylene Polymerization by Thioether Bridged Dinuclear Zirconocene Complex

2011 ◽  
Vol 213 ◽  
pp. 374-377 ◽  
Author(s):  
Yu Jing Nie ◽  
Ming Yang
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Ethylene Polymerization ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
High Concentration ◽  
Concentration Time ◽  
Cyclopentadienyl Ligand ◽  
Broad Molecular Weight Distribution ◽  
Higher Temperature

The thioether bridged Zirconocene complex [(C5H5)Cl2ZrC5H4CH2CH2]2S has been synthesized by treating the dilithium salts of the thioether bridged cyclopentadienyl ligand with two equivalents of C5H5ZrCl3(DME) and characterized by 1HMNR and elemental analysis. Homogenous ethylene polymerization by this complex has been conducted systematically in the presence of methylaluminoxane (MAO). The influence of the molar ratio [MAO]/[Cat], the catalyst concentration, time and temperature have been studied in detail. The catalytic activity of 1 is 6.46×105 g PE/mol•Cat•h. Higher temperature is favorable for increasing the catalytic activity for 1. A high concentration of the catalysts drops the catalytic activity as well as the molecular weight of polyethylene for the complex. High temperature gel permeation chromatography (HT-GPC) proves the production of polyethylene with a broad molecular weight distribution (MWD).

Preparation of Polyethylene with Vanadium/Titanium Bi-Metal Ziegler-Natta Catalysts

2014 ◽  
Vol 665 ◽  
pp. 335-338
Author(s):  
Tao Jiang ◽  
Xiang Lu Gao
Keyword(s):  
Ethylene Polymerization ◽  
Bimetallic Catalyst ◽  
Gel Permeation Chromatography ◽  
Catalyst System ◽  
Molar Ratio ◽  
Dsc Analysis ◽  
Scanning Calorimetry ◽  
Vanadium Titanium ◽  
Ziegler Natta Catalysts ◽  
C Nmr

The catalyst with magnesium chloride supported vanadium/titanium bimetallic Ziegler-Natta catalysts has been prepared. The effects of V/Ti molar ratio and dosage of α-olefin on catalytic activity of ethylene polymerization were investigated. Gel permeation chromatography (GPC),13C-NMR spectra and differential scanning calorimetry (DSC) analysis were performed to characterize the polymers. The results indicated that the bimetallic catalyst system produced PE with broad and bimodal MWD.

Deactivation of arenetitanium(II) bromoalane complexes in the cyclotrimerization of butadiene

1986 ◽  
Vol 51 (12) ◽  
pp. 2751-2759 ◽  
Author(s):  
Jindřich Poláček ◽  
Helena Antropiusová ◽  
Lidmila Petrusová ◽  
Karel Mach
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Model System ◽  
Highly Active ◽  
Catalytic Stability

The C6H6.Ti(II)(AlBr4)2 (Ib) catalyst deactivates during the butadiene cyclotrimerization to give a solid containing all titanium (mostly as TiBr3) and a mixture of AlBr3 and RAlBr2 compounds dissolved in benzene. The residual cationic catalytic activity of the deactivated Ib system is due to presence of AlBr3. In contrast to TiCl3, the deactivated Ib system and the model system TiBr3 + AlBr3 are not activated by the addition of EtAlCl2 in the presence of butadiene: the highly active benzenetitanium(II) system is re-constituted only after reduction of TiBr3 with Et3Al followed by the addition of EtAlCl2. The addition of Et2AlBr to Ib accelerates the deactivation of the system. Deactivation products of this system contain mainly Ti(II) species which forms benzenetitanium(II) catalytic system after addition of EtAlCl2. All the EtAlCl2 reactivated systems produce (Z, E, E)-1,5,9-cyclododecatriene with high catalytic stability and considerable selectivity (>90%). This behaviour points to the catalysis by benzenetitanium(II) chloroalane complexes containing only low amount of bromine atoms and ethyl groups.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

scholarly journals Highly Dispersed Pd Species Supported on CeO2 Catalyst for Lean Methane Combustion: The Effect of the Occurrence State of Surface Pd Species on the Catalytic Activity

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 772
Author(s):  
Yanxiong Liu ◽  
Changhua Hu ◽  
Longchun Bian
Keyword(s):  
Catalytic Activity ◽  
Oxygen Vacancies ◽  
Methane Combustion ◽  
Pd Nanoparticles ◽  
High Concentration ◽  
Ch4 Combustion ◽  
Highly Active ◽  
Δ Phase ◽  
Occurrence State ◽  
Comprehensive Characterization

The correlation between the occurrence state of surface Pd species of Pd/CeO2 for lean CH4 combustion is investigated. Herein, by using a reduction-deposition method, we have synthesized a highly active 0.5% PdO/CeO2-RE catalyst, in which the Pd nanoparticles are evenly dispersed on the CeO2 nanorods CeO2-R. Based on comprehensive characterization, we have revealed that the uniformly dispersed Pd nanoparticles with a particle size distribution of 2.3 ± 0.6 nm are responsible for the generation of PdO and PdxCe1−xO2−δ phase with –Pd2+–O2−–Ce4+– linkage, which can easily provide oxygen vacancies and facilitate the transfer of reactive oxygen species between the CeO2-R and Pd species. As a consequence, the remarkable catalytic activity of 0.5% Pd/CeO2-RE is related to the high concentration of PdO species on the surface of the catalyst and the synergistic interaction between the Pd species and the CeO2 nanorod.

scholarly journals A new highly active La2O3–CuO–MgO catalyst for the synthesis of cumyl peroxide by catalytic oxidation

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12532-12542
Author(s):  
HanShuang Liu ◽  
KaiJun Wang ◽  
XiaoYan Cao ◽  
JiaXin Su ◽  
Zhenggui Gu
Keyword(s):  
Catalytic Activity ◽  
Catalytic Oxidation ◽  
Highly Active

The La2O3–CuO–MgO catalyst acts on the oxidation of cumene and shows excellent catalytic activity through the coordination of surface and interior.

scholarly journals Ferrous and Cobaltous Chlorides Bearing 2,8-Bis(imino)quinolines: Highly Active Catalysts for Ethylene Polymerization at High Temperature

2010 ◽  
Vol 29 (24) ◽  
pp. 6837-6840 ◽  
Author(s):  
Shu Zhang ◽  
Wen-Hua Sun ◽  
Tianpengfei Xiao ◽  
Xiang Hao
Keyword(s):  
High Temperature ◽  
Ethylene Polymerization ◽  
Highly Active

scholarly journals Nef Associates with p21-Activated Kinase 2 in a p21-GTPase-Dependent Dynamic Activation Complex within Lipid Rafts

2004 ◽  
Vol 78 (23) ◽  
pp. 12773-12780 ◽  
Author(s):  
Kati Pulkkinen ◽  
G. Herma Renkema ◽  
Frank Kirchhoff ◽  
Kalle Saksela
Keyword(s):  
Catalytic Activity ◽  
Lipid Rafts ◽  
Lipid Raft ◽  
Kinase Activity ◽  
Highly Active ◽  
Membrane Compartment ◽  
Per Se ◽  
P21 Activated Kinase ◽  
Autoregulatory Mechanism ◽  
Pak2 Activation

ABSTRACT We have previously reported that Nef specifically interacts with a small but highly active subpopulation of p21-activated kinase 2 (PAK2). Here we show that this is due to a transient association of Nef with a PAK2 activation complex within a detergent-insoluble membrane compartment containing the lipid raft marker GM1. The low abundance of this Nef-associated kinase (NAK) complex was found to be due to an autoregulatory mechanism. Although activation of PAK2 was required for assembly of the NAK complex, catalytic activity of PAK2 also promoted dissociation of this complex. Testing different constitutively active PAK2 mutants indicated that the conformation associated with p21-mediated activation rather than kinase activity per se was required for PAK2 to become NAK. Although association with PAK2 is one of the most conserved properties of Nef, we found that the ability to stimulate PAK2 activity differed markedly among divergent Nef alleles, suggesting that PAK2 association and activation are distinct functions of Nef. However, mutations introduced into the p21-binding domain of PAK2 revealed that p21-GTPases are involved in both of these Nef functions and, in addition to promoting PAK2 activation, also help to physically stabilize the NAK complex.

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