DRIFTS study of the interaction of the AlEt3 cocatalyst with the internal donor ethyl benzoate in supported Ziegler–Natta catalysts

Potapov, A.G.; Букатов, Г. Д.; Захаров, В. А.

doi:10.1016/j.molcata.2008.11.002

Cited by 27 publications

(22 citation statements)

References 12 publications

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“…On the other hand, the long-wavelength shift of the bands in the PL spectra of these samples can be associated with interactions with neighboring molecules, for example, chlorine atoms or OH groups, always present in magnesium chloride due to the trace amounts of water. 25 , 37 …”

Section: Resultsmentioning

confidence: 99%

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New Insight into Titanium–Magnesium Ziegler–Natta Catalysts Using Photoluminescence Spectroscopy

et al. 2020

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This paper presents the results of study of titanium–magnesium catalysts often used in polymerization processes, by photoluminescence spectroscopy (PL) in combination with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The interaction of dibutyl phthalate (DBP) with MgCl2 was studied at DBPadded/Mg = 0–1 (mol/mol). The luminescence spectra with excitation at 278 nm and the excitation spectra for main emission bands were recorded. It was shown that DBP adsorbed on magnesium chloride, both in the form of donor–acceptor complexes (D+A–) and in the form of molecular complexes. At DBPadded/Mg <0.15, the formation of D+A– complexes occur predominantly; with an increase in DBPadded/Mg, the fraction of molecular complexes increases. Molecular complexes are destroyed during the treatment of the support by TiCl4. In this case, the structure of magnesium chloride is disordered and new coordination–unsaturated sites are formed. This work is a first attempt to apply PL spectroscopy in combination with DRIFTS spectroscopy to study titanium–magnesium Ziegler–Natta catalysts. The application of PL spectroscopy to such systems made it possible to detect interactions within and between donor molecules, which would be particularly challenging to achieve using other spectroscopic methods. Both spectroscopic methods provided crucial information about the existence of two types of complexes on the sample surface which is important for tuning the synthesis procedure of the titanium–magnesium catalysts for olefin polymerization.

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Section: Resultsmentioning

confidence: 99%

“…An activated MgCl 2 sample was synthesized accordingly to described procedure by reaction of magnesium with BuCl (at a molar ratio BuCl/Mg = 3) in n-heptane at 98 ℃, and then washed twice with the same solvent. 25 MgCl 2 (BuCl) sample (S BET = 70 m 2 /g) contained ∼10 wt.% of organic products.…”

Section: Methodsmentioning

confidence: 99%

New Insight into Titanium–Magnesium Ziegler–Natta Catalysts Using Photoluminescence Spectroscopy

et al. 2020

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“…This agrees with experimental findings. [46] However,i ti sp ossible that the donor displacementp roduct, AlEt 3 -eb,i sa lso adsorbed on the MgCl 2 surface, in close proximity to the Ti IV center, that is,t he AlEt 3 -ebspecies acts as ad onor. The free-energy profile for the AlEt 3 -eb donor is shown in Figure S10.…”

Section: Comparative Study Between Wd(ticl 4 )And the Donorsmentioning

confidence: 99%

“…In addition to the primary objective of investigating the possible role of the donors in the activation process, we have also investigated the competing possibilityo ft he donor detaching from the MgCl 2 surface through its interaction with the AlEt 3 group, ash as been observed in experimental studies, for the case of the eb donor. [46] This would diminish the donor influence on the activation process, and therefore has to be considered. It is also possible that the AlEt 3 coordinated donor species can act as an ew "donor" for the system.…”

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confidence: 99%

Effect of Donors on the Activation Mechanism in Ziegler–Natta Catalysis: A Computational Study

2016

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Full quantum chemical calculations, using density functional theory (DFT), have been conducted to explain the effect of donors on the “activation mechanism” in the Ziegler–Natta (Z–N) catalyst system. In the activation mechanism, the inactive TiIVCl4 catalyst converts into the active TiIIICl2Et catalyst with the help of the AlEt3 present in the system. The donors that have been considered in this study are: ethyl benzoate (eb), two representative diether cases, a phthalate donor, and a silyl ester donor. The results indicate that eb and the diether donor cases donor have a negative effect on the barriers for the activation mechanism. However, the eb donor can be displaced from the MgCl2 surface by AlEt3, which matches experimental observations. For the phthalate, silyl ester and TiCl3–OC4H8Cl cases, the results indicate that a significant induction period would be present in Z–N systems employing such donors or having such a catalytic center, before catalysis could commence.

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“…The absorption band at 1627 cm −1 can be assigned to the complex of (Al(C 2 H 5 ) 2 Cl) with carboxyl group of DEP [23]. In contrast to support (A) and catalyst (B) in IR spectra of C and D catalysts (Figure 2), a few absorption bands belonging to stretching vibrations of carbonyl groups were observed [24]. The doublet band at 1596–1583 cm −1 most probably belongs to (TiCl 4 DEP) 2 and (TiCl 4 DEHP) 2 surface complexes.…”

Section: Resultsmentioning

confidence: 99%

A Study of Ziegler–Natta Propylene Polymerization Catalysts by Spectroscopic Methods

et al. 2017

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Ziegler–Natta polymerization catalysts were characterized by a complex of surface- and bulk-sensitive methods (DRIFTS, XPS, ESR, and XAS = XANES + EXAFS). A diffuse-reflectance Fourier-transform IR spectroscopy (DRIFTS) study showed the presence of strong Lewis acid sites in different concentrations and absence of strong basic sites in the polymerization catalysts. X-ray photoelectron spectroscopy (XPS), electron-spin resonance (ESR), and (X-ray absorption near-edge structure (XANES) analysis revealed the presence of Ti4+, Ti3+, Ti2+, and Ti1+ species in the surface layers and in the bulk of catalysts. The samples under study differ drastically in terms of the number of ESR-visible paramagnetic sites. The EXAFS study shows the presence of a Cl atom as a nearest neighbor of the absorbing Ti atom.

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DRIFTS study of the interaction of the AlEt3 cocatalyst with the internal donor ethyl benzoate in supported Ziegler–Natta catalysts

Cited by 27 publications

References 12 publications

New Insight into Titanium–Magnesium Ziegler–Natta Catalysts Using Photoluminescence Spectroscopy

New Insight into Titanium–Magnesium Ziegler–Natta Catalysts Using Photoluminescence Spectroscopy

Effect of Donors on the Activation Mechanism in Ziegler–Natta Catalysis: A Computational Study

A Study of Ziegler–Natta Propylene Polymerization Catalysts by Spectroscopic Methods

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