Solubility of Ethene in <i>n</i>-Hexane and <i>n</i>-Heptane as Common Slurry-Phase Polymerization Solvents: Experimental Measurement and Modeling

Dashti, Ali; Mazloumi, Seyed Hossein; Akbari, Amir; Ahadiyan, Hamid Reza; Emami, Ali

doi:10.1021/acs.jced.5b00907

Cited by 17 publications

(22 citation statements)

References 9 publications

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“…Figure shows the ethylene mole fraction in n‐hexane at different pressures and temperatures (i.e., 50, 60, 70, and 75 °C). The S–L EOS predictions are in excellent agreement with experimental data obtained from different sources …”

Section: Dynamic Mass and Energy Balances For A Slurry‐phase Series Osupporting

confidence: 82%

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

Pladis

Baltsas

Meimaroglou

et al. 2018

Macro Reaction Engineering

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in low-pressure catalytic (e.g., Ziegler-Natta, metallocenes) solution, slurry and bulk phase reactors. Despite the success of metallocene catalysts the majority of commercial polyolefins are still produced by Ziegler-Natta and Philips chromium catalysts. [1] Continuous slurry-phase polymerization, in the presence of a heterogeneous Ziegler-Natta (Z-N) catalyst, is one of the most commonly employed processes in the production of polyolefins, including high-density polyethylene (HDPE), isotactic polypropylene (IPP) as well as their copolymers with higher olefins. [1][2][3][4][5][6][7][8][9][10] The Z-N slurry-phase olefin polymerization in a series of continuous stirred tank reactors (CSTRs) and loop-reactors continue to dominate the HDPE production, accounting for almost 70% of the total installed capacity. Polymerization in a series of reactors is often employed to control the comonomer incorporation rate and copolymer distribution, which is important for polyolefin grades and applications (e.g., pipes) that require excellent environmental stress crack resistance. The attractive combination of good flowability and improved mechanical properties is achieved by tailoring MWDs and controlling comonomer branching distribution. The slurry-phase HDPE process technology (see Figure 1) employs two or more stirred-tank reactors in series and utilizes a Z-N catalyst system composed of a titanium chloride compound and an alkyl aluminum cocatalyst. The process uses hydrogen as a chain-termination agent to control the molecular weight of the product and a comonomer to control the density of the polyethylene grade. [11] The process operates in a continuous mode using a cascade of two or three autoclave-type vessels. Each reactor can operate under a different hydrogen partial pressure, thereby allowing the control of the molecular weight distribution produced in each reactor of the series. Low molecular-weight polyethylene has a low viscosity and a fast crystallization rate, accounting for high polymer stiffness, whereas high molecular-weight polyolefins exhibit significantly higher toughness, but a much slower crystallization rate and a lower crystallinity together with a high melt viscosity due to extensive polymer chain entanglement. Typical polymerization conditions are: temperatures of 70-90 °C, pressure less than 10 bar and a reactor mean residence time of 45 min.Modeling A comprehensive mathematical model is developed to simulate the dynamic Ziegler-Natta ethylene-α-olefins copolymerization in a series of slurry-phase continuous stirred tank reactors. A generalized multisite kinetic mechanism is considered to describe the molecular and compositional developments (joint molecular weight-copolymer composition distribution) in a series of continuous stirred tank reactors (CSTRs). Dynamic macroscopic mole balances are derived to calculate the dynamic evolution of all species concentrations in three phases (i.e., gas, liquid, and polymer) of the multiphase system. The polymer molecular properties (i.e., molecular weight dist...

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Section: Dynamic Mass and Energy Balances For A Slurry‐phase Series Osupporting

confidence: 82%

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

Pladis

Baltsas

Meimaroglou

et al. 2018

Macro Reaction Engineering

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“…in catalytic performance, both in terms of activity and productivity (Figure 7 vs Figure 5). 72 The performance of the alkyl imido pre-catalyst 2c was the outlier, having given a lower activity, but similar productivity compared to that obtained at 60 °C, with the amount of polymer produced also having increased (Table 4, entry 1). For tests at 70 °C the activity increased consistently through the series 2d-g, although 2d showed the same catalyst lifetime as the other pre-catalysts, in contrast to its weaker performance at 60 °C (see Figure 5 and Figure 7).…”

Section: Impact Of Imido Substituent On Productmentioning

confidence: 94%

Exploration of Homogeneous Ethylene Dimerization Mediated by Tungsten Mono(imido) Complexes

et al. 2018

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“…The ethylene consumption of all catalysts at lower polymerization temperatures is much higher than that at 85 °C as shown in Table , which might result from the better dissolution of ethylene monomer in the solvent . The MW is strongly dependent on the polymerization temperature according to the study of Blom et al The MW of the polyethylene increases with the decreasing polymerization temperature, as shown in Table .…”

Section: Resultsmentioning

confidence: 86%

A Novel SiO₂‐Supported Fluorine Modified Chromium–Vanadium Bimetallic Catalyst for Ethylene Polymerization and Ethylene/1‐Hexene Copolymerization

Sun

Wang

Cheng

et al. 2017

Macro Reaction Engineering

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Phillips catalyst is one of the most significant industrial ethylene polymerization catalysts. Chemical modifications have been carried out to tune the Phillips catalyst performance and improve the polyethylene properties. After the modification of the catalyst by fluorine, the polyethylene product with higher molecular weight (MW) and narrower molecular weight distribution (MWD) is suitable for producing automobile fuel tanks. Vanadium containing Phillips catalyst enhances α‐olefin incorporation and MW regulation. In present work, fluorine modified and unmodified chromium–vanadium (Cr–V) bimetallic catalysts are prepared and explored. Compared with the fluorine‐free catalyst, the activities of F‐modified bimetallic catalysts slightly decrease with the increasing MW of the product and the hydrogen response increases slightly. Due to the synergistic effect of the chromium, vanadium and fluorine on the silica gel support, the short‐chain branch distribution (SCBD) of copolymers from F‐modified Cr–V bimetallic catalyst (Cr–V–F)600 is more beneficial than that of Cr–V bimetallic catalyst (Cr–V)600 and F‐modified Cr–V bimetallic catalyst (Cr–V–F)500. The fluorination of Cr–V bimetallic catalysts has not only preserved the high polyethylene activity of bimetallic active sites but also produced the advantage of the high MW ability from fluorine.

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Solubility of Ethene in n-Hexane and n-Heptane as Common Slurry-Phase Polymerization Solvents: Experimental Measurement and Modeling

Cited by 17 publications

References 9 publications

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

Exploration of Homogeneous Ethylene Dimerization Mediated by Tungsten Mono(imido) Complexes

A Novel SiO₂‐Supported Fluorine Modified Chromium–Vanadium Bimetallic Catalyst for Ethylene Polymerization and Ethylene/1‐Hexene Copolymerization

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Solubility of Ethene in n-Hexane and n-Heptane as Common Slurry-Phase Polymerization Solvents: Experimental Measurement and Modeling

Cited by 17 publications

References 9 publications

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

A Dynamic Simulator for Slurry‐Phase Catalytic Olefin Copolymerization in a Series of CSTRs: Prediction of Distributed Molecular and Rheological Properties

Exploration of Homogeneous Ethylene Dimerization Mediated by Tungsten Mono(imido) Complexes

A Novel SiO2‐Supported Fluorine Modified Chromium–Vanadium Bimetallic Catalyst for Ethylene Polymerization and Ethylene/1‐Hexene Copolymerization

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Product

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A Novel SiO₂‐Supported Fluorine Modified Chromium–Vanadium Bimetallic Catalyst for Ethylene Polymerization and Ethylene/1‐Hexene Copolymerization