Effect of hydrogen on the number of active centers and the propagation rate constant at ethylene polymerization over titanium-magnesium Ziegler-Natta catalysts

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Effect of hydrogen on the number of active centers and the propagation rate constant at ethylene polymerization over titanium-magnesium Ziegler-Natta catalysts. / Sukulova, V. V.; Barabanov, A. A.; Mikenas, T. B. et al.

In: Molecular Catalysis, Vol. 445, 01.02.2018, p. 299-306.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{d933a2bdf4fe4330b89bf336f84edd2a,

title = "Effect of hydrogen on the number of active centers and the propagation rate constant at ethylene polymerization over titanium-magnesium Ziegler-Natta catalysts",

abstract = "The effect of hydrogen on the number of active centers (СР) and the propagation rate constant (kP) at ethylene polymerization over titanium–magnesium catalysts is studied using quenching by radioactive carbon monoxide (14СО). The polymerization rate drops after hydrogen was added to the polymerization medium mainly due to the decrease in the calculated kP value. The changes in the polymerization rate and the experimental kP value observed after hydrogen was added or removed are found to be reversible. The data on the effect of the [H2]/[C2H4] molar ratio in the gas phase within the range of 0.125–1 on polymerization rate and the СР and kP values are obtained. Reduction of the kP value and a small decrease in the number of active centers are observed at the H2/C2H4 molar ratio ≥ 0.5. These findings were used to propose a scheme interpreting the effect of hydrogen on the СР and kP values. The scheme suggests that the decrease in the calculated kP value observed in the presence of hydrogen is related to the reversible formation of temporarily inactive dormant sites containing the titanium–polymer bond.",

keywords = "Ethylene polymerization, Number of active centers, Polymerization kinetics, Propagation rate constant, Ziegler-Natta catalysts, MECHANISM, PROPYLENE POLYMERIZATION, KINETIC FEATURES, CHAIN TRANSFER, POLYETHYLENE, VANADIUM-MAGNESIUM, MOLECULAR-WEIGHT DISTRIBUTION, SITES, OLEFINS, PROPENE POLYMERIZATION",

author = "Sukulova, {V. V.} and Barabanov, {A. A.} and Mikenas, {T. B.} and Matsko, {M. A.} and Zakharov, {V. A.}",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier B.V.",

year = "2018",

month = feb,

day = "1",

doi = "10.1016/j.mcat.2017.11.017",

language = "English",

volume = "445",

pages = "299--306",

journal = "Molecular Catalysis",

issn = "2468-8231",

publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Effect of hydrogen on the number of active centers and the propagation rate constant at ethylene polymerization over titanium-magnesium Ziegler-Natta catalysts

AU - Sukulova, V. V.

AU - Barabanov, A. A.

AU - Mikenas, T. B.

AU - Matsko, M. A.

AU - Zakharov, V. A.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - The effect of hydrogen on the number of active centers (СР) and the propagation rate constant (kP) at ethylene polymerization over titanium–magnesium catalysts is studied using quenching by radioactive carbon monoxide (14СО). The polymerization rate drops after hydrogen was added to the polymerization medium mainly due to the decrease in the calculated kP value. The changes in the polymerization rate and the experimental kP value observed after hydrogen was added or removed are found to be reversible. The data on the effect of the [H2]/[C2H4] molar ratio in the gas phase within the range of 0.125–1 on polymerization rate and the СР and kP values are obtained. Reduction of the kP value and a small decrease in the number of active centers are observed at the H2/C2H4 molar ratio ≥ 0.5. These findings were used to propose a scheme interpreting the effect of hydrogen on the СР and kP values. The scheme suggests that the decrease in the calculated kP value observed in the presence of hydrogen is related to the reversible formation of temporarily inactive dormant sites containing the titanium–polymer bond.

AB - The effect of hydrogen on the number of active centers (СР) and the propagation rate constant (kP) at ethylene polymerization over titanium–magnesium catalysts is studied using quenching by radioactive carbon monoxide (14СО). The polymerization rate drops after hydrogen was added to the polymerization medium mainly due to the decrease in the calculated kP value. The changes in the polymerization rate and the experimental kP value observed after hydrogen was added or removed are found to be reversible. The data on the effect of the [H2]/[C2H4] molar ratio in the gas phase within the range of 0.125–1 on polymerization rate and the СР and kP values are obtained. Reduction of the kP value and a small decrease in the number of active centers are observed at the H2/C2H4 molar ratio ≥ 0.5. These findings were used to propose a scheme interpreting the effect of hydrogen on the СР and kP values. The scheme suggests that the decrease in the calculated kP value observed in the presence of hydrogen is related to the reversible formation of temporarily inactive dormant sites containing the titanium–polymer bond.

KW - Ethylene polymerization

KW - Number of active centers

KW - Polymerization kinetics

KW - Propagation rate constant

KW - Ziegler-Natta catalysts

KW - MECHANISM

KW - PROPYLENE POLYMERIZATION

KW - KINETIC FEATURES

KW - CHAIN TRANSFER

KW - POLYETHYLENE

KW - VANADIUM-MAGNESIUM

KW - MOLECULAR-WEIGHT DISTRIBUTION

KW - SITES

KW - OLEFINS

KW - PROPENE POLYMERIZATION

UR - http://www.scopus.com/inward/record.url?scp=85039787120&partnerID=8YFLogxK

U2 - 10.1016/j.mcat.2017.11.017

DO - 10.1016/j.mcat.2017.11.017

M3 - Article

AN - SCOPUS:85039787120

VL - 445

SP - 299

EP - 306

JO - Molecular Catalysis

JF - Molecular Catalysis

SN - 2468-8231

ER -

ID: 9160463