Mesoporous silica （MS）, 3-aminopropyltriethoxysilane （APTES） modified mesoporous silica （AMS）, bis（3- trimethoxysilylpropyl）amine modified mesoporous silica （BAMS） and APTES modified solid spherical silica ...Mesoporous silica （MS）, 3-aminopropyltriethoxysilane （APTES） modified mesoporous silica （AMS）, bis（3- trimethoxysilylpropyl）amine modified mesoporous silica （BAMS） and APTES modified solid spherical silica （AS） were prepared and used to immobilize metallocene catalysts for ethylene polymerization. Gel permeation chromatography results showed that polyethylenes （PEs） catalyzed by AMS （or BAMS） supported metallocene catalysts at the molar ratios of Al/Zr = 100, 300 and 500 were of bimodal molecular weight distribution （BMWD）; while PEs catalyzed by the above catalysts at the molar ratios of Al/Zr 〉 800 were of monomodal molecular weight distribution （MMWD）. However, MS （or AS） supported metallocene catalysts could only produce PEs with MMWD in spite of the molar ratio of Al/Zr. It was because that AMS （or BAMS） supported catalysts possessed two active sites for ethylene polymerization at low molar ratios of Al/Zr due to the combination effects of mesopore geometrical constraint and amino groups of the supports, which was confirmed by X-ray photoelectron spectroscopy. This brings forward a novel and easy method for the synthesis of polyolefin with BMWD.展开更多
Polymerization of propylene was carried out under bulk process at 70 degrees C using the supported metallocene catalyst with four kinds of SiO2 as carrier with triethylaluminum used as cocatalyst. The morphology of th...Polymerization of propylene was carried out under bulk process at 70 degrees C using the supported metallocene catalyst with four kinds of SiO2 as carrier with triethylaluminum used as cocatalyst. The morphology of the products was studied by SEM. It was found the property of the carriers gave great effect on the fine structure of the products as well as the apperance.展开更多
The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene （PE） catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mes...The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene （PE） catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves （SAPO1 and SAPO2） were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.展开更多
基金supported by the National Natural Science Foundation of China(Nos.50525311,20734006 and 50621302)
文摘Mesoporous silica （MS）, 3-aminopropyltriethoxysilane （APTES） modified mesoporous silica （AMS）, bis（3- trimethoxysilylpropyl）amine modified mesoporous silica （BAMS） and APTES modified solid spherical silica （AS） were prepared and used to immobilize metallocene catalysts for ethylene polymerization. Gel permeation chromatography results showed that polyethylenes （PEs） catalyzed by AMS （or BAMS） supported metallocene catalysts at the molar ratios of Al/Zr = 100, 300 and 500 were of bimodal molecular weight distribution （BMWD）; while PEs catalyzed by the above catalysts at the molar ratios of Al/Zr 〉 800 were of monomodal molecular weight distribution （MMWD）. However, MS （or AS） supported metallocene catalysts could only produce PEs with MMWD in spite of the molar ratio of Al/Zr. It was because that AMS （or BAMS） supported catalysts possessed two active sites for ethylene polymerization at low molar ratios of Al/Zr due to the combination effects of mesopore geometrical constraint and amino groups of the supports, which was confirmed by X-ray photoelectron spectroscopy. This brings forward a novel and easy method for the synthesis of polyolefin with BMWD.
文摘Polymerization of propylene was carried out under bulk process at 70 degrees C using the supported metallocene catalyst with four kinds of SiO2 as carrier with triethylaluminum used as cocatalyst. The morphology of the products was studied by SEM. It was found the property of the carriers gave great effect on the fine structure of the products as well as the apperance.
基金the support of the National Natural Science Foundation of China （No. 20174039） the Ministry of Science and Technology of China （No. 2005CB623800）.
文摘The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene （PE） catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves （SAPO1 and SAPO2） were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.
