Study On The Synthesis And Properties Of Chromium Based Catalyst For Ethylene Polymerization

Bistriphenylsilyl chromate was prepared from triphenyl chlorosilane and potassiumdichromate, glacial acetic acid and cyclohexane as solvent. The optimized conditions forsynthesis were as follows: the reaction temperature was30℃, the reaction time was2h, themolar ratio of triphenyl chlorosilane to potassium dichromate was2.0:1.2, the volume ratio ofglacial acetic acid to cyclohexane was2:1. The structure was characterized by elementalanalysis, DSC and IR. The thermal stability, light stability and hydrolytic stability of theproduct were also tested. The product changed in presence of light, heat and water. Thepreparation of supported catalyst was studied and found active component was well dispersedon the surface of carrier by XRD characterization.A novel salicylic alidehyde imine chromium coordination complex was prepared, and theconditions of reaction were confirmed. The structure of the ligand and complex werecharacterized by IR, elemental analysis, XRD, NMR and UV. The complex was of1:2Cr（Ⅲ）,and had no melting point. The solublility, molar conductivity and thermal stability were tested,and the catalysis of complex in decoposition of hydrogen peroxide and polymerization ofethylene were also studied. The complex was well dissolved in DMF and DMSO. The molarconductivity of complex was33S·cm²·mol^-1, it was nonelectrolyte. The process of thermaldecomposition was consistent with the coordination forms of complex, the appatent activationenergy value for complex was250kJ·mol^-1, it has good stability. The decompostion rate ofhydrogen peroxide incresaed by54.9%, the ultraviolet absorption peak caused red shift ofcomplex, the decoloration of methyl violet reached58%, due to the addition of metal chelate.But the salicylic alidehyde imine chromium coordination complex showed no activity forethylene polymerization.