Deactivation study of zirconocene immobilization into Lewis acid and dual-shell silicas prepared by a nonhydrolytic sol-gel method

Ullmann, Marcius A.; Santos, João Henrique Zimnoch dos

doi:10.1016/j.jcat.2019.08.040

Cited by 6 publications

(1 citation statement)

References 55 publications

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“…Cp 2 ZrCl 2 /MAO [50] Silicas with Mg(OEt) [98] Dual-shell silica 3 mol % Zr/(SiO 2 + SiOR); Rate = 1.6 × 10 6 g.mol À 1 .h À 1 ; Cp 2 ZrCl 2 /MAO [96] Diatomite RS400# diatomite; Zr/RS400 = 0.058 wt.%; Mw = 90 to 100 kg.mol À 1 ;…”

Section: -470mentioning

confidence: 99%

Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization

2023

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Silica-based supports known as structured-mixed supports were evaluated in ethylene polymerization. These supports exhibit local surface heterogeneity due to the in situ growth of nanoparticles under the surface. Standard (N) and hybrid (NTw and NPu) nanosilicas were synthesized by a sol gel method. The metallocene (nBuCp) 2 ZrCl 2 catalyst was immobilized onto nanosilicas and onto the structured-mixed support (MN, MNTw, and MNPu). The zirconocene active sites on the nanoparticles exhibited high activity (5,071 kg.mol Zr À 1 .h À 1 .bar À 1 with NPu) using Pluronic® L-31 (Pu). An excellent catalytic performance (10,777 kg.mol Zr À 1 .h À 1 .bar À 1 ) was achieved when Zr was incorporated on a structured-mixed support, and a polymer with high molecular weight (Mw up to 224 kg.mol À 1 ), broad polydispersion (Mw. Mn À 1 = 3.1), high melting temperature (Tm = 142 °C), and crystallinity (Xc = 76 %) was generated using Tween®80 (Tw). The results showed that support characteristics, such as a large surface area, surface fractal structure, functionalization of nanoparticles with Tw or Pu, and nano/microdomains, influenced the nature and distribution of active sites, leading to a robust catalytic system that is easily synthesized. Silica-based nano/microparticles pretreated with Tween®80 are an adequate candidate for new catalytic supports for ethylene polymerization.

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Section: -470mentioning

confidence: 99%

Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization

2023

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Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

et al. 2021

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Organic-inorganic hybrid materials are nowadays intensely studied for potential applications in heterogeneous catalysis because their properties and catalytic behavior differ from pristine inorganic counterparts. The organic groups at the catalyst surface can modify not only its hydrophilicity, but also acidity, hydrothermal stability, porosity, etc. In some cases, such properties alteration leads to improved catalytic performance in terms of activity, selectivity, or stability. However, the choice of organic groups stays relatively narrow, as most reports focus on pendant methyl groups. Here, a series of mesoporous hybrid aluminosilicate materials containing various organic groups was prepared in one pot by nonhydrolytic sol-gel (NHSG). Both aromatic and aliphatic, pendant and bridging organic groups were incorporated. The presence of the organic groups in the bulk and at the outermost surface of the materials was verified by solid-state NMR and ToF-SIMS, respectively.Aluminum is mostly incorporated in tetrahedral coordination in the hybrid silica matrix. The organically modified mesoporous aluminosilicate samples were tested as catalysts in the gas phase ethanol dehydration (which relies on solid acids) and most of them outperformed the purely inorganic catalyst benchmark. While a direct influence of surface hydrophilicity or hydrophobicity (as probed by water sorption and water contact angle measurements) appeared unlikely, characterization of acidity (IR-pyridine) revealed that the improved performance for hybrid catalysts can be correlated with a modification of the acidic properties. In turn, acidity is determined by the quality of the dispersion of Al centers in the form of isolated sites in the hybrid silica matrix. All in all, this study establishes a "ranking" for a variety of organic groups in terms of their effect on gas-phase ethanol dehydration to ethylene; ethylene yield decreases in this order: bridging xylylene ≈ pendant methyl > pendant benzyl > bridging methylene ≈ inorganic benchmark (no organic groups) > bridging ethylene.

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Non-hydrolytic sol–gel as a versatile route for the preparation of hybrid heterogeneous catalysts

Smeets

Stýskalík

Debecker

2021

J Sol-Gel Sci Technol

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Deactivation study of zirconocene immobilization into Lewis acid and dual-shell silicas prepared by a nonhydrolytic sol-gel method

Cited by 6 publications

References 55 publications

Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization

Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization

Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

Non-hydrolytic sol–gel as a versatile route for the preparation of hybrid heterogeneous catalysts

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Deactivation study of zirconocene immobilization into Lewis acid and dual-shell silicas prepared by a nonhydrolytic sol-gel method

Cited by 6 publications

References 55 publications

Supported Catalyst (nBuCp)2ZrCl2 on Nano/Micro Domains for High Performance Ethylene Polymerization

Supported Catalyst (nBuCp)2ZrCl2 on Nano/Micro Domains for High Performance Ethylene Polymerization

Non-hydrolytic sol–gel route to a family of hybrid mesoporous aluminosilicate ethanol dehydration catalysts

Non-hydrolytic sol–gel as a versatile route for the preparation of hybrid heterogeneous catalysts

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Product

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Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization

Supported Catalyst (nBuCp)₂ZrCl₂ on Nano/Micro Domains for High Performance Ethylene Polymerization