Search results for "1-Hexene"
showing 9 items of 9 documents
Studies on the microstructure of ethylene/1-hexene copolymers prepared over heterogeneous Ziegler - Natta catalysts
2000
Three MgCl 2(THF) 2-supported, AlEt 2Cl-activated VOCl 3, VCl 4 and TiCl 4 Ziegler - Natta catalysts were used to copolymerize ethylene with 1-hexene in the presence of hydrogen to prepare low-M well-soluble copolymers that could be analyzed by 13C-NMR. The spectra (Fig. 1) showed resonance signals due to ethylene and 1-hexene units in positions unaffected by catalyst type and with intensities related to the degree of comonomer incorporation into the copolymer. The triad sequence distribution and comonomer reactivity ratios (r) were calculated by the Randall method [11] and Bernoulli statistics based on the known copolymer composition. The latter appeared to be the more valid in predicting …
Hydroformylation of 1-Hexene over Rh/Nano-Oxide Catalysts
2013
The effect of nanostructured supports on the activity of Rh catalysts was studied by comparing the catalytic performance of nano- and bulk-oxide supported Rh/ZnO, Rh/SiO₂ and Rh/TiO₂ systems in 1-hexene hydroformylation. The highest activity with 100% total conversion and 96% yield of aldehydes was obtained with the Rh/nano-ZnO catalyst. The Rh/nano-ZnO catalyst was found to be more stable and active than the corresponding rhodium catalyst supported on bulk ZnO. The favorable morphology of Rh/nano-ZnO particles led to an increased metal content and an increased number of weak acid sites compared to the bulk ZnO supported catalysts. Both these factors favored the improved catalytic performan…
Microstructure of ethylene-1-hexene and ethylene-1-octene copolymers obtained over Ziegler–Natta catalysts supported on MgCl 2 (THF) 2
2001
Abstract The ethylene copolymerizations with 1-hexene or 1-octene in the presence of hydrogen using three catalysts, MgCl 2 (THF) 2 /VOCl 3 /Et 2 AlCl, MgCl 2 (THF) 2 /VCl 4 /Et 2 AlCl, MgCl 2 (THF) 2 /TiCl 4 /Et 2 AlCl, were investigated. It was found that the addition of hydrogen into the copolymerization feed reduces the molecular weight of the copolymers produced and decreases the activity of all the studied catalysts. The microstructure of the copolymers obtained was determined on the basis of 13 C NMR investigations and the reactivity ratios of the comonomers were calculated. The lack of tendency of the olefin comonomers to the creation of the polymer block was confirmed. It was found…
Zirconium and hafnium complexes of the thio(bisphenolato) ligand: synthesis, structural characterization and testing as 1-hexenepolymerizationcatalys…
2009
Thio(bisphenolato) complexes of the type [M2(mu-tbop-kappa3O,S,O)2Cl4] [M = Zr 1, Hf 2 and tbop = 2,2-thiobis{4-(1,1,3,3-tetramethyl-butyl)phenolate}] were prepared by HCl elimination from tbopH2 and MCl4. Substitution of the chlorides in 1 and 2 by 2,6-diisopropylphenolato groups (dipp) generates new compounds [M2(mu-tbop-kappa3O,S,O)2(dipp)4] (M = Zr 3, Hf 4). The structures of 1-4 were confirmed by NMR spectroscopy; complexes 3 and 4 were further investigated by X-ray crystallography. These studies showed 1-4 to be dimers either in the solid state or in solution and to have metal centers adopting distorted octahedral geometry. However treatment of MCl4 with [Al2(mu-OEt)2(tbop-kappa3O,S,O…
Studies on ethylene/1-hexene copolymerization over the zirconocene catalyst supported on MAO-modified MgCl2(THF)2. The effect of copolymerization con…
2002
Badania dotyczą układu katalitycznego MgCl2(THF)2/MAO/Cp2ZrCl2/MAO (MAO — metyloaluminoksan). Stwierdzono, że zarówno aktywność tego układu katalitycznego, jak i właściwości kopolimerów w znacznym stopniu zależą od stosunku molowego Al:Zr (zmienianego w przedziae 1500—7000) i od temperatury kopolimeryzacji (tabele 1 i 2), natomiast wpływ czasu kopolimeryzacji jest mniejszy (tabela 3). Aktywność katalizatora oraz zawartość 1-heksenu wbudowanego do kopolimeru zwiększają się ze wzrostem temperatury i stosunku Al:Zr, a jednocześnie maleje ciężar cząsteczkowy i temperatura topnienia produktów. Ustalono także, że osadzenie katalizatora cyrkonocenowego na stosowanym nośniku powoduje zwiększenie je…
Synthesis and characterization of ethylene-1-hexene copolymers prepared by using MgCl2(THF)2-supported Ziegler-Natta catalysts
2000
Ethylene was copolymerized with 1-hexene over vanadium (VOCl3 and VCl4) and titanium (TiCl4) catalysts supported on MgCl2(THF)2 and activated with Et2AlCl. So far these catalyst systems have not been known as initiators of ethylene-1-hexene copolymerization. The vanadium catalysts were more active than the titanium catalyst and, at identical comonomer concentrations in the feed, gave rise to a greater incorporation of 1-hexene into the copolymer. Even at relatively low fractions of 1-hexene, the MgCl2(THF)2-supported catalysts affected much the copolymer properties like density, melting point and crystallinity.
Spektrofotometryczna metoda oznaczania składu kopolimerów etylen/1-heksen
2000
Zmodyfikowano znaną z literatury spektrofotometryczną (FT-IR) metodę oznaczania składu kopolimerów etylenu z α-olefinami i wykorzystano ją do oznaczania składu kopolimerów etylenu z 1-heksenem o bardzo dużym ciężarze cząsteczkowym (~ 106) (tabela 1). Wyprowadzono zależność umożliwiającą obliczenie zawartości 1-heksenu w kopolimerach etylen/1-heksen na podstawie stosunku wartości absorbancji pasm ACH31379 / ACH21369 [równanie (8)] oznaczonych po separacji odpowiednich pasm analitycznych (rys. 7 i 8). Ustalono też, że absorbancji pasm z zakresu 722 cm-1 nie powinno się wykorzystywać w proponowanej metodzie ilościowej (tabela 1).
Studies of intermolecular heterogeneity distribution in ethylene/1-hexene copolymers using DSC method
2002
The investigation of the intermolecular composition distribution of an ethylene/1-hexene copolymers using DSC method has been carried out. The known methods: step crystallization (SC) and successive self-nucleation/annealing (SSA) have been adapted for this purpose, and particularly, the optimal condition of the process have been chosen to enable the best fractional crystallization of the copolymer. The method has been applied for fractionation of two ethylene/1-hexenecopolymers synthesized with supported vanadium and zirconocene catalysts and having similar concentrations of 1-hexene. Although metallocene catalysts are known from their more homogeneous structure of active sites in comparis…
Studies of ethylene/1-hexene copolymerization over zirconocene catalyst supported on MAO-modified MgCl2(THF)2. The effect of copolymerization conditi…
2003
Composition of catalytic system and copolymerization reaction conditions influence on heterogeneity of ethylene/1-hexene copolymers obtained over MgCI2(THF)2/MAO/Cp2ZrCl2/MAO catalyst was studied. One of the DSC techniques, i.e. successive self-nucleation/annealing (SSA) method allowing separation of the polymer into fractions with differing chemical composition in result of alternating crystallization and melting cycles was applied. It was found that the intermolecular heterogeneity exists inside all studied samples irrespective of the reaction conditions (temperature and time) and the catalyst composition (Al/Zr molar ratio). It was also confirmed that catalyst composition has a considera…