摘要
A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic system is composed of β-diketonate zirconium complexes,i.e.(acac)2ZrCl2(Ⅰ)and(dbm)2ZrCl2(Ⅱ)as catalyst precursors,diethylaluminium chloride(AlEt2Cl)as a co-catalyst for ethylene oligomerization and methylaluminoxane(MAO)as another one for the in situ copolymerization with ethylene.The oligomers obtained were mainly α-olefins,and the contents of them in weight were 76.84 for Ⅰ and 65.99 for Ⅱ,while the part being able to be copolymerized was 62.12 and 55.32 for Ⅰ and Ⅱ,respectively.The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2Cl/MAO or Ⅱ/AlEt2Cl/MAO.13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2.1/1000C,including ethyl group of 1.2/1000C,butyl group of 0.8/1000C and longer branches of 0.1/1000C.With increasing the molar ratio of AlEt2Cl to MAO,the melting temperature of the polymer obtained decreased from 133.7 to 116.7 ℃ for Ⅰ/AlEt2Cl/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity.The catalytic activities for catalyst Ⅰ/AlEt2Cl/MAO and Ⅱ/AlEt2Cl/MAO were from 2.48×104 to 0.10×104 g PE/(mol Zr·h)and from 1.00×104 to 0.32×104 g PE/(mol Zr·h),respectively.The results indicate that the branched polyethylene can be obtained by such a catalytic system.
A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis, with ethylene as single monomer. Such catalytic system is composed of β-diketonate zirconium complexes, i.e. （acac）2ZrCl2（ Ⅰ ） and （dbm）2ZrCl2 （ Ⅱ ） as catalyst precursors, diethylaluminium chloride（AlEt2Cl） as a co-catalyst for ethylene oligomerization and methylaluminoxane（MAO） as another one for the in situ copolymerization with ethylene. The oligomers obtained were mainly α-olefins, and the contents of them in weight were 76. 84% for Ⅰ and 65.99% for Ⅱ , while the part being able to be copolymerized was 62. 12% and 55.32% for Ⅰ and Ⅱ , respectively. The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2CL/MAO or Ⅱ/AlEt2CL/MAO. ^13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2. 1/1000C, including ethyl group of 1.2/1000C, butyl group of 0. 8/ 1000C and longer branches of 0. 1/1000C. With increasing the molar ratio of AlEt2C1 to MAO, the melting temperature of the polymer obtained decreased from 133.7 to 116. 7 ℃ for Ⅰ/AlEt2CL/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity. The catalytic activities for catalyst Ⅰ/AlEt2C1/MAO and Ⅱ/AlEt2Cl/MAO were from 2. 48 × 10^4 to 0. 10 × 10^4 g PE/（mol Zr · h） and from 1.00 × 10^4 to 0. 32× 10^4 g PE/（mol Zr · h）, respectively. The results indicate that the branched polyethylene can be obtained by such a catalytic system.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第2期430-432,共3页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:50573018)资助
关键词
乙烯原位共聚
支化聚乙烯
β-二酮锆配合物
一氯二乙基铝
甲基铝氧烷
In situ copolymerization of ethylene
Branched polyethylene
β-Diketonate zirconium complex
Diethylaluminium chloride
Methylaluminoxane
