Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr‐V Bimetallic Catalyst

Bao, Liu; Tian, Zhong‐Qun; Jin, Yulong; Zhao, Ning; Liu, Boping

doi:10.1002/mren.201700059

Cited by 14 publications

(12 citation statements)

References 75 publications

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“…Generally, the low‐ and the high‐MW peaks are originated from the chromium and vanadium centers in the CrV bimetallic polyethylene catalyst, respectively. [ 32 ] The PDIs of the products by CrV‐1/1‐CA, CrV‐1/2‐CA, and CrV‐1/3‐CA are broader than the counterparts, suggesting that more active sites are involved in the reaction. For CrV‐1/1‐CA and CrV‐1/1 catalysts, the molecular weight of the products are similar as 10.5 × 10 5 g mol −1 , with the PDI obviously changed from 50.1 to 58.2.…”

Section: Resultsmentioning

confidence: 99%

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CrV Bimetallic Phillips Catalyst Prepared by Citric Acid‐Assisted Impregnation on Ethylene Polymerization

Liu

Zhang²,

He³

et al. 2020

Macro Chemistry & Physics

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/macp.202000010. Three CrV bimetallic Phillips catalysts are developed by a citric acid-assisted impregnation method and studied in ethylene homopolymerization and ethylene/1-hexene copolymerization. The method benefits to the dispersion of bimetallic active sites, especially for the V ones. The electron binding energy shift of V 2p 3/2 in CrV-1/2-CA suggests the increased electron deficiency of V active center. The CrV-1/2-CA, CrV-1/3-CA catalysts present higher activity, broader molecular weight distribution, than the counterparts without CAassisted impregnation, suggesting more active sites involved in the reaction. The 1-hexene is higher inserted in the polyethylene by CrV-1/2 than the CrV-1/2-CA. But the results of temperature rising elution fractionation-successive selfnucleation and annealing (TREF-SSA) show the thinner platelet thickness at the high molecular weight parts of high-density polyethylene by CrV-1/2-CA, suggesting the higher insertion of 1-hexene and higher tensile properties. The CrV-1/2-CA also shows the more hydrogen-regulated response in the polymerization. The deconvolution of the gel permeation chromatography curves presents the higher fractions of high molecular weight polymer component.

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Section: Resultsmentioning

confidence: 99%

“…The final melting curve was carried out on TA DSC Q200 with the authors' previous reported program. [ 31,32 ]…”

Section: Methodsmentioning

confidence: 99%

CrV Bimetallic Phillips Catalyst Prepared by Citric Acid‐Assisted Impregnation on Ethylene Polymerization

Liu

Zhang²,

He³

et al. 2020

Macro Chemistry & Physics

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“…It is well stablished that the first and most important parameter controlling the final polymer properties is the catalyst [5,6]. On the other hand, it is noticed that the nature of this important chemical is practically undeniable without the presence of an activator known as cocatalyst [7,8]. Many advances have been made in the catalysts structural studies and polymerization condition, although the effect of important factors such as electron donor, cocatalyst, and comonomer in the catalyst performance and polymerization process is not very well explored and understood [9].…”

Section: Introductionmentioning

confidence: 99%

Exploring cocatalyst type effect on the Ziegler-Natta catalyzed ethylene polymerizations: experimental and DFT studies

Posada‐Pérez

Masoori

Nekoomanesh

et al. 2022

Preprint

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Due to the important role of cocatalyst in the polymerization process employing industrially favored Ziegler-Natta catalysts, its effect on kinetic behavior, catalyst activity, and polymer properties is discussed. In this paper triethyl aluminum (TEA) and triisobutyl aluminum (TIBA) have been used as the main cocatalyst ingredient with 10-20 mole percent of diethyl aluminum chloride (DEAC) and ethyl aluminum dichloride (EADC) cocatalysts. Among studied systems, neat TEA demonstrated the highest activity. Moreover, TEA-DEAC and TEA-EADC cocatalysts revealed a built-up kinetic profile, while TIBA-DEAC and TIBA-EADC show a decay-type kinetic curve. According to melt flow index results, no considerable change in flowability was detected in the synthesized polyethylenes (PE). On the other hand, the ethylene insertion and chain termination mechanisms were scrutinized by means of density functional calculations using Ti active center located in (110) and (104) facets of the MgCl2 surface. Results revealed that TiCl4 supported (110) termination favors the PE chain production, being the ethylene insertion, the rate-determining step. To shed light on the bulkiness level of employed cocatalysts, buried volume (VBur) together with the two-dimensional map of cocatalyst molecules were considered. Higher VBur of TIBA can explain its lower activity and decay type kinetic profile obtained in the experimental section.

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“…[19][20][21] Our group utilized the advantages of vanadiumbased catalysts to hybridize different kinds of bimetallic to produce bimodal PE with improved proccessability. [22][23][24][25][26] However, the activities of vanadium-based catalysts were not as high as Ziegler-Natta catalyst. Our group also developed the modified silica-supported vanadium-based catalyst to produce UHMWPE with higher activity compared with the previously published supported vanadium-based catalysts.…”

Section: Introductionmentioning

confidence: 99%

Study of Silica‐Supported Chromocene Catalysts for Ethylene Polymerization

Wang

Gao

et al. 2020

Macro Chemistry & Physics

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Ultrahigh molecular weight polyethylene (UHMWPE) has drawn great interest from researchers because it possesses many excellent properties such as superb strength and impact resistance, which other polyolefin cannot achieve. A silica‐supported chromocene catalyst, for the production of UHMWPE, is successfully developed. The polyethylene (PE) produced by the chromocene catalyst can achieve a molecular weight (MW) of over 3 × 106 g mol−1 with narrow molecular weight distribution (MWD) a value of approximately three. The activity calculated by Cr per unit reaches the maximum when the loading of Cr is 1.7 wt%. With the increasing loading of chromocene, the MW shows a small increase and the MWD becomes narrower. The chromocene catalyst for ethylene polymerization also shows a significant hydrogen response. With 0.01 MPa hydrogen added into the ethylene polymerization, the MW of the PE decreases immensely to only 0.7 × 106 g mol−1 and the MWD is broadened from <3 to ≈12. If the amount of hydrogen increases, the MW continues to decrease and the MWD becomes wider. The MW of the PE produced by the chromocene catalyst can be regulated easily by adjusting the amount of hydrogen.

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Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr‐V Bimetallic Catalyst

Cited by 14 publications

References 75 publications

CrV Bimetallic Phillips Catalyst Prepared by Citric Acid‐Assisted Impregnation on Ethylene Polymerization

CrV Bimetallic Phillips Catalyst Prepared by Citric Acid‐Assisted Impregnation on Ethylene Polymerization

Exploring cocatalyst type effect on the Ziegler-Natta catalyzed ethylene polymerizations: experimental and DFT studies

Study of Silica‐Supported Chromocene Catalysts for Ethylene Polymerization

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