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Gas Phase Polymerization of Conjugated Dienes with Supported Rare Earth Catalyst: Kinetics and Molecular Weight Control

Author: LiJunFei
Tutor: ZhangYiFeng；NiXuFeng
School: Zhejiang University
Course: Polymer Chemistry and Physics
Keywords: Supported rare earth catalysts Alkylaluminum Butadiene Isoprene Gas-phase polymerization Block copolymerization Molecular weight and molecular weight distribution Dynamics
CLC: O631.5
Type: Master's thesis
Year: 2002
Downloads: 127
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Abstract

Gas-phase polymerization of its less investment, low energy consumption, environment pollution concern and has been successfully applied in the industrial production of ethylene, propylene and a polymerization method has a broad prospect. In recent years, double-olefin gas-phase polymerization of butadiene, isoprene, and other research gradually expand our group carried out the first in the country in the of butadiene vapor phase polymerization studies. Firstly using composite aluminum alkyl cocatalyst, the development of efficient load applicable to the gas phase polymerization of the bis-olefin type rare earth catalyst, polymerization of butadiene vapor and its regulation of the molecular weight of the polymer, isoprene gas phase homopolymerization of polymerizable system dynamics, and to investigate the copolymerization of butadiene / isoprene Gas. Research and development for the first time the SiO: load to a rare earth compound-containing alkyl aluminum cocatalyst catalytic system Nd (naph);-Al2EthCl-Al (i-Bu) :/ AlH (i-Bu): for butadiene gas phase polymerization. The catalytic system of butadiene gas phase polymerization has a high catalytic activity, the catalytic efficiency in the of 1000 ~ 2300KgPBd/molNd · H. Systematically investigated the cocatalyst with rare earth compound, the molar ratio (Al / Nd), tri-iso-butyl aluminum hydride and isobutyl aluminum ratio (AL / H) cocatalyst, polymerization temperature, reaction time, the amount of dispersing agent on the polymerization The molecular weight of the product, and found that by varying the above factors can effectively regulate the molecular weight and molecular weight distribution of the the polymerization proceeds butadiene rubber. Wherein, Al / Nd, the Al / H of the polymerization product MW affect significantly, i.e. with the catalytic system in the increase of the amount of aluminum alkyl and aluminum alkyl of AlH (i-Bu): content increased, the molecular weight decreased significantly. The polymerization temperature, reaction time, a dispersing agent for the polymerization product of molecular weight less affected. By adjusting the composition and proportions of the co-catalyst in the catalyst system and the polymerization reaction time may be in the weight average molecular weight for of 40 ~~ 100 x 10'g / mol to effectively regulate the molecular weight of the resulting polybutadiene rubber. Also investigated the influence of the above factors on the polymerization product of the molecular weight distribution, and found that the polymerization time, alkyl amount of aluminum species larger molecular weight distribution of the polymerization product, the polymerization product has a molecular weight distribution index of between 2.7 to 4.0. The the GPC study also confirmed the rare earth catalytic polymerization of butadiene system of two active centers: C * and C: *. Wherein C1 * quick response, but short life, easy to lose the Activity and chain transfer reaction; while C: * slow reaction, with the characteristics of the quasi-living polymerization, precisely due to the ratio of the two active centers in the catalyst system is different, resulting in The change in molecular weight of the resulting polymer. Supported rare earth catalytic system for the first time for isoprene gas-phase polymerization, the study of different rare earth catalytic performance of the catalyst system consisting of different ligands. Found that the catalytic activity of the order of different rare earth Nd gt; gt; Gd gt; of Er gt; the Sm, of different ligands rare earth compounds catalytic activity order naph gt; Psov gt; the acac gt; CF3COO '. Within the experimental range the isoprene gas phase polymerization of the top main catalyst of rare earth is Nd (naph):. A detailed examination of Nd (naph) 3-Al2Et3Cl3-Al (i-Bu) 3/AlH (i-Bu), the catalytic system composed of SiO: a load (such as: Al / Nd, Cl / Nd, Al / H molar ratio etc.) Journal of Zhejiang University and the polymerization conditions (such as the polymerization temperature and reaction time, etc.) the influence on the polymerization, considering the catalytic activity and product molecular weight, The preferred conditions called for lfNd CI / Nd = 4, AI 4, The polymerization temperature is 50C, isoprene gas phase polymerization, the polymerization activity of 1000-1500K to noisy the D / molNd · h, the resulting polyisoprene weight average molecular weight of about 50 Chuan 'g / ITIOI, cis structure content is 935 %. Research 80. The load * ... knock the N Hirokawa BC Buchuan Bo hh system catalytic the isoprene vapor phase polymerization kinetics behavior. Compare the different composition of the catalyst, the catalyst concentration and polymerization temperature. . Polymerization rate. The study found that the polymerization kinetics curve are attenuated, i.e. in the early stages of the polymerization reaction, the polymerization reaction rate rapidly increases, and reached the highest 5 called minutes, thereafter, the reaction rate is slowly reduced. Further AlfNd molar ratio increases, the shorter the time the polymerization rate reaches a peak. Found that under different reaction temperatures, the polymerization reaction rate is reduced with the extension of the polymerization reaction time, decrease its maximum rate, the rate is large decline. The polymerization temperature is low, the maximum value of the rate of reaction appeared later, but the rate of decline is also relatively flat. *, ** N load knock *. The Yichuan D. C the BU pair of two Bll) / Chuan *** u), catalytic systems for butadiene - isoprene gas phase copolymerization. The resulting product was analyzed by DSC, and GPC showed that a block copolymer. Infrared analysis showed that the copolymer polybutadiene chain cis-l, 4 content and polyisoprene chain of cis-l, 4 total content of about 95%. The initial effects of the type of catalyst, monomer feed ratio, polymerization temperature on the copolymerization product composition and found that the monomer feed ratio, polymerization temperature copolymerization product shadow noon larger. The FTIR and 'H-NyllL copolymer polyisoprene chain content of between 10% -70%.

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