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Organic/inorganic Composite Support for Immobilizing Catalyst Using in Ethylene Polymerization

Author: LiWei
Tutor: YangYongRong;WangJingZuo;JiangBinBo
School: Zhejiang University
Course: Chemical Engineering
Keywords: Composite catalyst Bimodal polyethylene Organic / inorganic composite carrier Carrier broken A styrene - acrylic acid copolymer Phase inversion method Metallocene catalyst Ziegler-Natta catalysts Late transition metal catalysts
CLC: TQ325.12
Type: PhD thesis
Year: 2011
Downloads: 118
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The development of high-end polyethylene specialized material needs through the close integration of catalyst technology and production processes on the molecular scale polyethylene molecular structure and molecular structure of the design, such as molecular weight and molecular weight distribution, degree of branching and branched distribution and so on, in order to meet the requirements of the end-use performance, bimodal polyethylene is a typical representative. Bimodal polyethylene is a bimodal distribution of molecular weight into polyethylene. Wherein the low molecular weight portion allows a material having a good processing performance, the high molecular weight fraction for the material to provide better performance. The composite catalyst is one of the method is the primary method of the preparation of bimodal polyethylene. The thesis \The the vinyl composite catalyst of new organic / inorganic composite microspheres carrier. Concrete work and the main results are as follows: (1) by the phase inversion method of the styrene - acrylic acid copolymer (PSA) is deposited in the carrier of the surface of the silica (Si02), prepared well dispersed, the surface densification PSA/SiO2 composite microspheres . Infrared spectroscopy, thermal gravimetric analysis, particle size distribution, scanning electron microscopy and BET method carrier preparation process on the structure and morphology of the carrier. The study showed that the concentration of the polymer and the amount of non-solvent can be adjusted by controlling the evaporation rate of a non-solvent, the surface morphology of the carrier of the composite microspheres. The composite microsphere carrier in PSA benign solvent toluene supported catalyst, should be added to the large amount of non-solvent, in order to maintain the stability of the morphology of microsphere carrier. (2) Based on the phase inversion process the composite microspheres carrier load (n-BuCp) 2ZrCl2/PSA/TiCl3 composite catalyst. The polymer film will be separated from the two conventional catalysts (metallocene and Ziegler-Natta catalysts), i.e. first Ziegler-Natta catalyst supported on the inorganic support as a kernel, the polymer film is then uniformly deposited on the catalyst surface of the inorganic carrier, Finally, the metallocene catalyst solution was rapidly load in the polymer film, to obtain the inner titanium Tomoji type (n-BuCp) 2ZrCl2/PSA/TiCl3 composite catalyst. Tandem reaction process under laboratory conditions, simulate industrial slurry double boiler, the preparation of high molecular weight high degree of branching in the first-stage reaction of the ethylene / 1 - hexene copolymers, the preparation of low molecular weight is low in the second-stage reaction, The degree of branching of the polymer. Slurry polymerization, the results show that the activity of the catalyst is slowly released, duration of activity (8 h) was significantly longer than the load on the inorganic carrier of the catalyst, the melt flow of the resulting polyethylene comparison in width (M121.6/M12.16) reached 79, the molecular weight The distribution reach 18.6. Experimental Study of the polymeric carrier in the composite microsphere carrier, and found that, in the polymerization process of the organic carrier of PSA on the auxiliary catalyst MMAO having a significant barrier effect. Changing the ethylene / 1 - alkenyl of polymerization reaction time by scanning electrical microscopy (SEM), infrared spectroscopy (FTIR), shown differential scanning calorimetry heat meter (DSC) and the high temperature gel chromatography instrument (GPC) study found that the form of product, branched degree of crystallinity, the melting temperature and the molecular weight after the start of the polymerization 40min hours were significantly change, indicates that the early stages of the polymerization reaction, the catalyst is an external load on the organic carrier PSA (n-BuCp) 2ZrCl2 catalyst is mainly involved in the reaction, when the polymerization 40min after reaction, in the catalyst interior TiCl3 catalyst gradually participate in the reaction, when the polymerization is carried out to 2 h, TiCl3 catalyst heavily involved in the reaction. Further, the combination of experimental data to explore the growth mechanism of polyethylene particles in the composite catalyst in the polymerization process. Finally, blends of polyethylene blends by DSC and rheology. (3) Based on the phase inversion process the composite microspheres carrier load (n-BuCp) 2ZrCl2/PSA/TiCl3 composite catalyst (within the titanium Tomoji \The inner titanium outer metallocene gas phase polymerization of the composite catalyst activity is lower than the results in slurry polymerization, is 2.95 × 105gPE the · (molZr) -1 · h-1 · bar-1. The Experiment using n-BuSnCl3 PSA modified by BET, the particle size analysis of the structural characteristics of the carrier before and after modification, infrared analysis means. Ethylene gas-phase polymerization results showed that the modified catalyst has high activity of 2.56 × 106 gPE the · (molZr) -1 · h-1 · bar-1. Further, experimental analysis polyethylene properties of the product under different polymerization time, the outer PSA crushing behavior of the carrier during the polymerization, and the results were compared with ethylene slurry polymerization. The results show that the solvent swellable PSA carrier, the uniform release of the activity of the catalyst plays a crucial role in the supported catalyst of the composite carrier is more suitable for a slurry polymerization. (4) based on the phase inversion process of the composite microspheres carrier load Fe (acac) 3/2, 6 - bis (1 - (2 --diisopropylbenzene amino ethyl)) catalyst, in the production of α-olefins Meanwhile, to obtain a high degree of crystallinity polyethylene. Ethylene slurry polymerization results showed that the catalyst to produce a high degree of crystallinity (72%) of low molecular weight polyethylene, while the production of C4-C26 α-olefin. The chemical environment of the polymer carrier, as well as the polymerization conditions (co-catalyst, pressure, temperature and ferroaluminum ratio) on the catalyst activity and product properties, and found that the temperature on the polymerization product in a mass ratio of α-olefin with polyethylene (liquid solid. ratio) of the greatest impact. Magnesium chloride-modified PSA after the load 2,6 - bis (1 - (2 - cumene aminoethyl)) pyridine / Fe (acac) 3 of polyethylene produced molecular weight low (Mw = 11.9 × 104g-mol-1 larger), a degree of crystallinity, can be used to do the low molecular weight part of the bimodal polyethylene. (5) based on the phase inversion process, the composite microspheres the vector load TiCl4/Cp2ZrCl2 composite catalyst in a single reactor with TEA as the sole co-catalyst, the production of bimodal polyethylene. PSA wrapped MAO activated of the Silicone load Cp2ZrCl2 catalyst surface after TiCl4 load on the PSA within Mau outer titanium composite catalyst. Ethylene slurry polymerization results showed that the outer layer of PSA on TEA having a barrier effect, so that only TEA as cocatalyst, to activate the outer TiCl4 catalyst while the catalyst to remain active within a certain polymerization time, so that the inner Cp2ZrCl2, eventually prepared bimodal polyethylene.

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CLC: > Industrial Technology > Chemical Industry > Synthetic resins and plastics industry > Polymer resin and plastic > Polyolefin plastic > Polyethylene
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