Study of hydrogen effect in propylene polymerization on (with) the MgCl2-supported ziegler-natta catalyst—part 2. Effect of CS2 on polymerization centres

Vizen, E.I.; Rishina, L. A.; Sosnovskaja, L.N.; Dyachkovsky, F.S.; Dubnikova, I. L.; Ladygina, T. A.

doi:10.1016/0014-3057(94)90144-9

Cited by 26 publications

(14 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increasing the concentration of hydrogen to a certain level can lead to an increase in the reaction rate . From Figure it appears that, at least for the catalyst used in this part of the study, the optimum hydrogen concentration in terms of activity for the conditions studied here is approximately 2% when no hexane is present in the gas phase.…”

Section: Resultsmentioning

confidence: 84%

“…Hydrogen is often used in olefin polymerization to control the molecular weight distribution, but it also has an effect on the reaction rate. Increasing the hydrogen concentration in the reactor will lead to an increase in the rate of polymerization for PP and to a decrease in the average molecular weight . It has been shown that heavier components can influence the way hydrogen is absorbed in PE, so we will also investigate this effect for propylene polymerization.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Study of the Gas Phase Polymerization of Propylene: The Impact of Catalyst Treatment, Injection Conditions and the Presence of Alkanes on Polymerization and Polymer Properties

Martins

Cancelas

McKenna

2016

Macro Reaction Engineering

View full text Add to dashboard Cite

Propylene is polymerized in the gas phase in a 2.5 L semibatch reactor using a commercially available supported Ziegler–Natta (ZN) catalyst. The mode of injection (wet vs dry), the impact of including a prepolymerization step, and of changing the composition of the gas phase are systematically investigated in terms of their influence on the instantaneous polymerization rate and polymer properties. Prepolymerization is observed to enhance the polymerization activity. This is attributed, at least in part, to the effect of prepolymerization step in decreasing local particle overheating in the initial instants of reaction. Furthermore, a noticeable decrease of the catalyst activity is observed when the catalyst is injected dry as compared to when is first wetted with paraffinic oil before being charged to the reactor. Adding a hydrocarbon to the catalyst can eventually reduce the risk of overheating during the critical initial instants of polymerization since it increases resistance of the diffusion of monomer to the active sites, acting as an “in situ” prepolymerization. Methods that increased the productivity also lead to an improvement of the powder morphology. Finally, it is found that adding vaporized iso‐hexane to the gas phase provokes an increase in the instantaneous polymerization rate, and increases the impact of hydrogen on the rate and molecular weight.

show abstract

Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

A Study of the Gas Phase Polymerization of Propylene: The Impact of Catalyst Treatment, Injection Conditions and the Presence of Alkanes on Polymerization and Polymer Properties

Martins

Cancelas

McKenna

2016

Macro Reaction Engineering

View full text Add to dashboard Cite

show abstract

“…As mentioned, hydrogen was used for controlling the molecular weight of polyolefins in the coordination polymerization with decrease in the molecular weight 5, 35–38…”

Section: Resultsmentioning

confidence: 99%

Preparation of bimodal polypropylene in two‐step polymerization

Abedi

Hassanpour

2006

J of Applied Polymer Sci

View full text Add to dashboard Cite

Polymerization of propylene was carried out by using MgCl 2 .EtOH.TiCl 4 .DIBP.TEA.cHMDMS catalyst system in n-heptane, where MgCl 2 , EtOH, TiCl 4 , DIBP (diisobutyl phthalate), TEA (triethyl aluminum), and cHMDMS (cyclohexyl methyl dimethoxy silane) were support, ethanol for alcoholation, catalyst, external donor, cocatalyst (activator), and internal donor, respectively. The catalyst activity and polymer isotacticity were studied by measuring the produced polymer and its solubility in boiling n-heptane, respectively. The molecular weight and molecular weight distribution of the polymers were evaluated by gel permeation chromatography. Hydrogen was used for controlling the molecular weight. For producing the bimodal polypropylene, the polymerization was carried out in two steps (i.e., in the presence and absence of hydrogen). It was found that the catalyst showed high activity and stereoselectivity, on the other hand, bimodal polymer could simply be produced in two-step polymerization by using MgCl 2 .EtOH.TiCl 4 .DIBP.TEA.cHMDMS catalyst system. Meanwhile, the effect of the step of the hydrogen adding on propylene polymerization was investigated. It was shown that the addition of hydrogen in the second step was more suitable.

show abstract

“…Specifically, in the case of the titanium-based Ziegler-Natta (TiCl 4 /MgCl 2 ) polymerization catalysts, such systems are strongly inhibited by alcohol, organic amines and sulfites, as shown by Eley et al [6], Ballard et al [7], Grayson and McDaniel [8] and Vizen et al [9]. For these catalysts, traces of oxygenated compounds in the parts per billion (ppb) level are enough to engender significant loss of catalytic activity, because they can compete with ethylene for the Ti active site.…”

Section: Introductionmentioning

confidence: 91%

Modified-sorbents for acetone adsorption: Application in ethylene polymerization process

Gollmann

Capeletti

Miranda

et al. 2009

Chemical Engineering Journal

View full text Add to dashboard Cite

Study of hydrogen effect in propylene polymerization on (with) the MgCl2-supported ziegler-natta catalyst—part 2. Effect of CS2 on polymerization centres

Cited by 26 publications

References 6 publications

A Study of the Gas Phase Polymerization of Propylene: The Impact of Catalyst Treatment, Injection Conditions and the Presence of Alkanes on Polymerization and Polymer Properties

A Study of the Gas Phase Polymerization of Propylene: The Impact of Catalyst Treatment, Injection Conditions and the Presence of Alkanes on Polymerization and Polymer Properties

Preparation of bimodal polypropylene in two‐step polymerization

Modified-sorbents for acetone adsorption: Application in ethylene polymerization process

Contact Info

Product

Resources

About