Density functional theory was used to optimize structures of different methylaluminoxane nanotubes with general formula [（AIOMe）2]n, [（AlOMe）3]n and [（A1OMe）4]n cycle unit, where n ranges from 1 to 10. To explor...Density functional theory was used to optimize structures of different methylaluminoxane nanotubes with general formula [（AIOMe）2]n, [（AlOMe）3]n and [（A1OMe）4]n cycle unit, where n ranges from 1 to 10. To explore the stability of nanotubes, the binding energies and total energies are calculated. The results indicate that [（A1OMe）3]n and [（A1OMe）4]n have the stable structure of nanotubes. When n is 3, they have the most stable structure in all systems. Moreover, [（A1505）]n and [（A17OT）]n are also considered, but their dimers have irregular and distorted structures. So [（A1505）]n and [（A17OT）]n nanotubes are impossible to exist.展开更多
Novel highly active eta(5)-pentamethylcyclopentadienyltribenzyloxy titanium catalyst activated by modified methylaluminoxane (m-MAO) was prepared for styrene syndiospecific polymerization. The influences of the conten...Novel highly active eta(5)-pentamethylcyclopentadienyltribenzyloxy titanium catalyst activated by modified methylaluminoxane (m-MAO) was prepared for styrene syndiospecific polymerization. The influences of the contents of trimethylaluminum (TMA) in m-MAO and external addition of tri-isobutylaluminum (TIBA) on the distribution of the oxidation states of titanium were investigated in detail. The Ti (III) is in favour of styrene syndiospecific polymerization in higher catalytic activity.展开更多
A novel poly(1\|butene) was synthesized with η 5 \|pentamethylcyclopentadienyl\|tribenzyloxytitanium(Cp\+*Ti(OBz)\-3) and modified methylaluminoxane(MAO). The influence of various conditions (e.g., catalyst compositi...A novel poly(1\|butene) was synthesized with η 5 \|pentamethylcyclopentadienyl\|tribenzyloxytitanium(Cp\+*Ti(OBz)\-3) and modified methylaluminoxane(MAO). The influence of various conditions (e.g., catalyst composition, temperature, Al/Ti, pressure of monomer, and catalyst concentration) on the catalytic activity, molecular weight of the products were investigated in detail. It was found that the catalyst exhibited highest activity of 91 3kgPB/molTi·h at \%T\%=30℃, and Al/Ti(mol/mol)=200. The catalytic activity and molecular weight were sensitive to the TMA content in MAO and external TIBA. Catalytiac activity and molecular weight were decreased with increasing the content of TMA in MAO.External addition of TIBA can deactivated the catalyst. Molecular weight of the products was increased with decreasing temperature and Ti concentration. The catalyst had the highest activity at a Ti concentration of 1 0×10 -3 mol/L. The molecular weight of poly(1\|butene) is high, over one million by GPC method. The results showed that with this catalyst system, a high molecular weight poly(1\|butene) can be synthesized.展开更多
文摘Density functional theory was used to optimize structures of different methylaluminoxane nanotubes with general formula [（AIOMe）2]n, [（AlOMe）3]n and [（A1OMe）4]n cycle unit, where n ranges from 1 to 10. To explore the stability of nanotubes, the binding energies and total energies are calculated. The results indicate that [（A1OMe）3]n and [（A1OMe）4]n have the stable structure of nanotubes. When n is 3, they have the most stable structure in all systems. Moreover, [（A1505）]n and [（A17OT）]n are also considered, but their dimers have irregular and distorted structures. So [（A1505）]n and [（A17OT）]n nanotubes are impossible to exist.
文摘Novel highly active eta(5)-pentamethylcyclopentadienyltribenzyloxy titanium catalyst activated by modified methylaluminoxane (m-MAO) was prepared for styrene syndiospecific polymerization. The influences of the contents of trimethylaluminum (TMA) in m-MAO and external addition of tri-isobutylaluminum (TIBA) on the distribution of the oxidation states of titanium were investigated in detail. The Ti (III) is in favour of styrene syndiospecific polymerization in higher catalytic activity.
文摘A novel poly(1\|butene) was synthesized with η 5 \|pentamethylcyclopentadienyl\|tribenzyloxytitanium(Cp\+*Ti(OBz)\-3) and modified methylaluminoxane(MAO). The influence of various conditions (e.g., catalyst composition, temperature, Al/Ti, pressure of monomer, and catalyst concentration) on the catalytic activity, molecular weight of the products were investigated in detail. It was found that the catalyst exhibited highest activity of 91 3kgPB/molTi·h at \%T\%=30℃, and Al/Ti(mol/mol)=200. The catalytic activity and molecular weight were sensitive to the TMA content in MAO and external TIBA. Catalytiac activity and molecular weight were decreased with increasing the content of TMA in MAO.External addition of TIBA can deactivated the catalyst. Molecular weight of the products was increased with decreasing temperature and Ti concentration. The catalyst had the highest activity at a Ti concentration of 1 0×10 -3 mol/L. The molecular weight of poly(1\|butene) is high, over one million by GPC method. The results showed that with this catalyst system, a high molecular weight poly(1\|butene) can be synthesized.
