scholarly journals Enhancing thermostability of iron ethylene polymerization catalysts through N,N,N-chelation of doubly fused α,α′-bis(arylimino)-2,3:5,6-bis(hexamethylene)pyridines

2019 ◽  
Vol 9 (8) ◽  
pp. 1933-1943 ◽  
Author(s):  
Zheng Wang ◽  
Randi Zhang ◽  
Wenjuan Zhang ◽  
Gregory A. Solan ◽  
Qingbin Liu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
High Catalytic Activity ◽  
Polymerization Catalysts ◽  
Fe Catalyst

At temperatures up to 80 °C, high catalytic activity and high molecular weight PE was achievable using the Fe-catalyst depicted.

scholarly journals Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1078
Author(s):  
Hang Zhang ◽  
Zhipeng Ma ◽  
Yunpeng Min ◽  
Huiru Wang ◽  
Ru Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Catalytic Activity ◽  
Activated Carbon ◽  
Reaction Time ◽  
High Molecular Weight ◽  
Reaction Temperature ◽  
Water Soluble ◽  
High Catalytic Activity ◽  
High Molecular Weight Chitosan

Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the single-factor experiments, the reaction temperature, the reaction time, the amount of hydrogen peroxide and the loading capacity of PTA were selected as the influencing factors to study the catalyzed oxidation of hydrogen peroxide and degradation of high molecular weight chitosan. The results of IR showed that the catalyst had a Keggin structure. The results of the mercury intrusion test showed that the pore structure of the supported PTA catalyst did not change significantly, and with the increase of PTA loading, the porosity and pore volume decreased regularly, which indicated that PTA molecules had been absorbed and filled into the pore of activated carbon. The results of Response Surface Design (RSD) showed that the optimum reaction conditions of supported PTA catalysts for oxidative degradation of high molecular weight chitosan by hydrogen peroxide were as follows: reaction temperature was 70 ℃, reaction time was 3.0 h, the ratio of hydrogen peroxide to chitosan was 2.4 and the catalyst loading was 30%. Under these conditions, the yield and molecular weight of water-soluble chitosan were 62.8% and 1290 Da, respectively. The supported PTA catalyst maintained high catalytic activity after three reuses, which indicated that the supported PTA catalyst had excellent catalytic activity and stable performance compared with the PTA catalyst.

Syndiospecific polymerization of styrene by half-titanocene catalysts with the sulfur-containing donor ligand

e-Polymers ◽  
2014 ◽  
Vol 14 (4) ◽  
pp. 277-281 ◽  
Author(s):  
Wei Wang ◽  
Gang Zheng ◽  
Hongtao Wang
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
High Catalytic Activity ◽  
Narrow Molecular Weight Distribution ◽  
Donor Ligand ◽  
High Yields ◽  
Sulfur Containing

AbstractMonocyclopentadienyl titanium complexes of the type Cp*TiX2 L (Cp*=C5 Me5, 1: L=C6 F5 S, X=OMe; 2: L=C6 F5 S, X=Cl; 3: L=2, 6-Me2-C6 H3 S, X=OMe) have been synthesized with high yields. These complexes are used as the catalysts for the syndiospecific polymerization of styrene. High catalytic activity is observed, and a polymer with high molecular weight and narrow molecular weight distribution is obtained. It is concluded that not only the sulfur-containing donor ligand but also the anion ligand strongly affects the polymerization activity and the molecular weight of the resultant polymer.

Chromium complexes supported by the bidentate PN ligands: synthesis, characterization and application for ethylene polymerization

2018 ◽  
Vol 47 (38) ◽  
pp. 13459-13465 ◽  
Author(s):  
Quande Zheng ◽  
Dejuan Zheng ◽  
Binghao Han ◽  
Shaofeng Liu ◽  
Zhibo Li
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
Chromium Complexes ◽  
Highly Active ◽  
Imine Ligands

Chromium complexes bearing phosphine–imine ligands are highly active for ethylene polymerization and produce HDPE with a high molecular weight.

scholarly journals Chromium ethylene polymerization catalysts bearing sterically enhanced α,α′-bis(imino)-2,3:5,6-bis(pentamethylene)pyridines: Tuning activity and molecular weight

Polymer ◽  
2019 ◽  
Vol 171 ◽  
pp. 87-95 ◽  
Author(s):  
Chantsalnyam Bariashir ◽  
Zheng Wang ◽  
Gregory A. Solan ◽  
Chuanbing Huang ◽  
Xiang Hao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ethylene Polymerization ◽  
Polymerization Catalysts

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).

Asymmetric bis-salicylaldiminato binuclear titanium complexes for ethylene polymerization and copolymerization

2021 ◽  
Author(s):  
Yawen Qin ◽  
Tingcheng Li ◽  
Xiong Chen ◽  
Jian Li ◽  
Xiang Meng ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Ethylene Polymerization ◽  
Titanium Complexes ◽  
Broad Molecular Weight Distribution

Polyolefins with high molecular weight and broad molecular weight distribution have attracted great attention due to their ease of processing and wide applications. In this paper, methylene-bridged asymmetric disalicylaldimine ligands...

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