Two novel Fe(Ⅱ) diimine complexes have been synthesized. In combination with MAO, they generate active catalytic systems that oligomerize ethylene with both high catalytic activity and high selectivity for a-olefins....Two novel Fe(Ⅱ) diimine complexes have been synthesized. In combination with MAO, they generate active catalytic systems that oligomerize ethylene with both high catalytic activity and high selectivity for a-olefins. The effects of substituents on the aryl ring, reaction temperatures and molar ratios of Al/Fe on catalytic activity and product distribution are studied.展开更多
A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with...A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with methylalurninoxane（MAO）, nickel complexes A--C all exhibited good catalytic activity[turnover frequency=5.2×10^5-16.3×10^5 g/（mol Ni-h）] and oligomer selectivity（above 85%, mass fraction） in ethylene oligomerization. In addition, C8--C12 olefins occupied an important proportion in the products of oligomers. Under the conditions of 4.0 MPa, 25℃ and A1/Ni molar ratio of 275, the catalytic selectivity of A/MAO system toward C8-C12 was about 30. 1%（mass fraction）, and the content of C8--C12 a-olefins was consistently above 70%. Furthermore, besides the ligand environment, the catalytic properties of A-C were substantially affected by experimental parameters, such as the reaction pressure, reaction temperature and A1/Ni ratio.展开更多
Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethyl...Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane （MAO）. The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers〉C4. The activity of 3b-MAO complex is 6.3×10^7 g/（molNi.h） at 50 ℃. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.展开更多
Olefin oligomerization reaction catalyzed by new catalyst systems（a Br？nsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst） has been investigat‐ed. The synthe...Olefin oligomerization reaction catalyzed by new catalyst systems（a Br？nsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst） has been investigat‐ed. The synthesized Br？nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy（FT‐IR）, ultraviolet‐visible spectroscopy（UV）, ^1H nuclear magnetic resonance（NMR）, and ^13 C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co‐catalysts, catalyst ratios（mole ratio of ionic liquid to co‐catalyst）, reac‐tion time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1‐（4‐sulfonic acid）butyl‐3‐hexylimidazolium hydrogen sulfate（[HIMBs]HSO4） exhibited the best catalytic activity under the tested reaction con‐ditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respec‐tively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experi‐mental products.展开更多
基金This work was supported by the Special Funds for the Major State Basic Research Projects (Grant No. G1999064800)the National Natural Science Foundation of China (Grant No. 29734141) the State Key Laboratory of Engineering Plastics (Grant No. 0062).
文摘Two novel Fe(Ⅱ) diimine complexes have been synthesized. In combination with MAO, they generate active catalytic systems that oligomerize ethylene with both high catalytic activity and high selectivity for a-olefins. The effects of substituents on the aryl ring, reaction temperatures and molar ratios of Al/Fe on catalytic activity and product distribution are studied.
文摘A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with methylalurninoxane（MAO）, nickel complexes A--C all exhibited good catalytic activity[turnover frequency=5.2×10^5-16.3×10^5 g/（mol Ni-h）] and oligomer selectivity（above 85%, mass fraction） in ethylene oligomerization. In addition, C8--C12 olefins occupied an important proportion in the products of oligomers. Under the conditions of 4.0 MPa, 25℃ and A1/Ni molar ratio of 275, the catalytic selectivity of A/MAO system toward C8-C12 was about 30. 1%（mass fraction）, and the content of C8--C12 a-olefins was consistently above 70%. Furthermore, besides the ligand environment, the catalytic properties of A-C were substantially affected by experimental parameters, such as the reaction pressure, reaction temperature and A1/Ni ratio.
基金This work is supported by PetroChina Company Limited (No.030414-01)
文摘Novel Ni（II）-based acetyliminopyridine complexes 1b, 2b, 3b （1-3b）, which are synthesized from ligands 1a, 2a, 3a （1-3a） and [NiCl2（DME）], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane （MAO）. The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers〉C4. The activity of 3b-MAO complex is 6.3×10^7 g/（molNi.h） at 50 ℃. The activities and molecular weight distributions of oligomers show significant reliance on the structures of catalyst precursors.
基金supported by the National Natural Science Foundation of China(21473225)
文摘Olefin oligomerization reaction catalyzed by new catalyst systems（a Br？nsted‐acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co‐catalyst） has been investigat‐ed. The synthesized Br？nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy（FT‐IR）, ultraviolet‐visible spectroscopy（UV）, ^1H nuclear magnetic resonance（NMR）, and ^13 C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co‐catalysts, catalyst ratios（mole ratio of ionic liquid to co‐catalyst）, reac‐tion time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1‐（4‐sulfonic acid）butyl‐3‐hexylimidazolium hydrogen sulfate（[HIMBs]HSO4） exhibited the best catalytic activity under the tested reaction con‐ditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respec‐tively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experi‐mental products.
