TY - JOUR

T1 - Ethylene Polymerization over Supported Vanadium-Magnesium Catalysts with Different Vanadium Content: The Effect of Hydrogen on Molecular Weight Characteristics of the Produced Bimodal Polyethylene

AU - Mikenas, Tatiana

AU - Zhao, Zenghui

AU - Guan, Peng

AU - Matsko, Mikhail

AU - Zakharov, Vladimir

AU - Wu, Wei

N1 - Funding Information: This work was financially supported by the PetroChina Petrochemical Research Institute (Daqing) and the Ministry of Science and Higher Education of the Russian Federation within the governmental order for Boreskov Institute of Catalysis (project AAA-A21-121011490008-3). Publisher Copyright: © 2022 by the authors.

PY - 2022/9

Y1 - 2022/9

N2 - Data are presented on the activity of supported vanadium-magnesium catalysts (VMCs) with different vanadium content in ethylene polymerization and the molecular weight characteristics of the produced polyethylene. The VC1 catalyst, with a very low vanadium content (0.12 wt.%), showed a sixfold higher activity per unit weight of vanadium than the VC2 catalyst with a high-vanadium content (4.0 wt.%). Additionally, the total activity of VC2 (kg PE/g cat·h) was fivefold higher when compared to VC1. The introduction of hydrogen in polymerization leads to a considerable decrease in the activity of both catalysts. The polyethylene obtained in the presence of hydrogen over both catalysts has a broad bimodal molecular weight distribution (MWD) with a distinct shoulder in the high-molecular region (Mw ≥ 106 g/mol). Decomposition of the MWD curves of bimodal polyethylene into two fractions (high- and low-molecular fractions) made it possible to determine for the first time the ratio of the reaction rate constants of chain transfer with hydrogen (KtrH) and polymer chain propagation (Kp) for two groups of the VMC active sites producing low- and high-molecular fractions of bimodal polyethylene.

AB - Data are presented on the activity of supported vanadium-magnesium catalysts (VMCs) with different vanadium content in ethylene polymerization and the molecular weight characteristics of the produced polyethylene. The VC1 catalyst, with a very low vanadium content (0.12 wt.%), showed a sixfold higher activity per unit weight of vanadium than the VC2 catalyst with a high-vanadium content (4.0 wt.%). Additionally, the total activity of VC2 (kg PE/g cat·h) was fivefold higher when compared to VC1. The introduction of hydrogen in polymerization leads to a considerable decrease in the activity of both catalysts. The polyethylene obtained in the presence of hydrogen over both catalysts has a broad bimodal molecular weight distribution (MWD) with a distinct shoulder in the high-molecular region (Mw ≥ 106 g/mol). Decomposition of the MWD curves of bimodal polyethylene into two fractions (high- and low-molecular fractions) made it possible to determine for the first time the ratio of the reaction rate constants of chain transfer with hydrogen (KtrH) and polymer chain propagation (Kp) for two groups of the VMC active sites producing low- and high-molecular fractions of bimodal polyethylene.

KW - catalytic reaction kinetics

KW - experimental methods

KW - heterogeneous catalysis

KW - theoretical methods

UR - http://www.scopus.com/inward/record.url?scp=85138662408&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/b4ea8b8d-312d-38be-8024-6e62875455a4/

U2 - 10.3390/catal12090985

DO - 10.3390/catal12090985

M3 - Article

AN - SCOPUS:85138662408

VL - 12

JO - Catalysts

JF - Catalysts

SN - 2073-4344

IS - 9

M1 - 985

ER -