Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This ...

Current heterogeneous catalysts lack the fine steric and electronic tuning required for catalyzing the selective dimerization of ethylene to 1-butene, which remains one of the largest industrial processes still catalyzed by homogeneous catalysts. Here, we report that a metal-organic framework catalyzes ethylene dimerization with a combination of activity and selectivity for 1-butene that is pre...

A series of anilido–imine chromium complexes have been used as precursors to catalyze homoand copolymerization of ethylene and norbornene. The chromium complexes activated with methylalumoxane (MAO) exhibit good activities for homopolymerization of ethylene (E) to produce linear polyethylene and moderate activities for norbornene (N) polymerization to afford vinyl-type polynorbornene. Ethylene–...

A diffuse reflectance infrared Fourier-transform (DRIFT) study has been conducted at 373 K and 1 bar on an industrial Cr/Ti/SiO2 Phillips-type catalyst modified with, and without, triethylaluminium (TEAl) as co-catalyst. The reaction rate of the polymerization of ethylene, as monitored by the increase in the methylene stretching band of the growing polyethylene (PE), has been investigated as a ...

Two late transition metal catalysts based on 2,6-bis(imino)pyridine iron(II) were synthesized by introducing methyl substitution (catalyst A) and t-Butyl substitution (catalyst B) at the ortho position of the aryl rings of the ligand. Comparative ethylene polymerizations using the catalysts showed quiet different behaviors. The activity of catalyst A was higher than that of catalyst B in all of...

ethylene was polymerized in slurry phase over a ticl4/mg(oc2h5)2 catalyst activated by al(c2h5)3. it was shown experimentally that mass transfer resistance has no effect on polymerization kinetics. after estimation ofthe active site concentration by inhibition method with carbon monoxide, the effects of polymerization temperature, monomer and cocatalyst  oncentrations and hydrogen were investig...

Ethylene-propylene-diene rubbers (EPDM) are one of the most important polyolefin materials widely commercialized and used in various industries recent years. The production EPDM is based solely on catalytic coordination polymerization processes. development new catalysts processes for synthesis has expanded range products their manufacturing terms energy efficiency, processability, environmenta...

a fi zr-based catalyst of bis[n-(3,5-dicumylsalicylidene)-2′,6′­diisopropylanilinato]zirconium(iv) dichloride was prepared and used for polymerization of ethylene. the effects of reaction conditions on the polymerization were examined in detail. the increase in ethylene pressure and rise in polymerization temperature up to 35 oc were favorable for catalyst/mao to raise the catalytic activity as...

Phosphino-phenolate neutral nickel catalysts 1-3/B(C6F5)3, without the help of any organoaluminum compound, were found to be efficient catalytic systems for norbornene polymerization and its copolymerization with norbornene derivatives. The amount of B(C6F5)3 required for achieving a high efficiency (3 equiv.) was markedly lower compared to previous reports, and high molecular weight polymers w...