Extremely Active MAO Free Chromium Catalytic System for Ethylene Tetramerization
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초록
내용
Catalyst systems discovered by Sasol is comprised of Cr(III) source PNP ligand and MAO. When it comes to the large scale use of the Sasol system, the use of MAO has economic because of expensive price of MAO. we developed a catalytic system using inexpensive alkylaluminum in place of MAO. [(CH3CN)4CrIIICl2]+[B(C6F5)4]- isolated in the reaction of CrCl3(THF)3 with [(CH3CN)4Ag]+[B(C6F5)4]- is reacted with iPrN(PPh2)2 or [CH3(CH2)16]2CHN(PPH2)2 to produce cationic chromiumIII species bearing B(C6F5)4- anion. The cationic (PNP)CrIII complexes paired with [B(C6F5)4]- anions demonstrate high activity with satisfactory selectivity when activated with common trialkylaluminum species in chlorobenzene. That these activity and selectivity are acceptable is compared to original Sasol system. If it is not paired with a trityl cation, The [B(C6F5)4]- anion is compatible with trialkylaluminum species. So [(PNP)CrCl2(CH3CN)2]+[B(C6F5)4]-/Et3Al exhibited considerably higher activity