新型硅胶负载型有机无机复合铬系催化剂的制备及乙烯聚合研究
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摘要
目前全球塑料制品市场上,高等级高耐压高密度聚乙烯(HDPE)管材料作为输水或天然气管道等广泛应用于建筑行业,而且应用市场还在不断扩大。该种管材主要是通过双釜串联工艺生产出的乙烯/a-烯烃(通常是1-丁烯,1-己烯或1-辛烯)共聚物加工制成。目前,双釜串联工艺及其催化剂技术仍为发达国家所垄断。为了替代当前高能耗、高成本的双釜工艺,开发低能耗、低成本的单釜工艺是现今的主流趋势。但在学术界和工业界开发应用于单釜工艺的新型催化剂体系依旧是一项巨大挑战。无机铬Phillips催化剂(硅胶负载氧化铬)和有机铬S-2催化剂(硅胶负载双三苯基硅烷铬酸酯)是两种重要的工业聚乙烯催化剂,这两种铬系催化剂在乙烯聚合行为及其产物特征方面均具有各自的优势。本文通过利用Phillips催化剂表面的剩余羟基进一步负载双三苯基硅烷铬酸酯(bis(triphenysilyl) chromate, BC)制备了一种新型硅胶负载型有机无机复合铬系催化剂,并最终成功应用于单釜工艺实现了高等级聚乙烯管材料的生产。该复合铬系催化剂结合了两者各自的优点,特别是具有较优的短支链分布调控性能。通过催化剂表征,乙烯均聚和乙烯/1-己烯共聚行为及其产物结构特征的研究,本文对影响复合催化剂体系的几个重要因素包括BC添加量、共聚单体1-己烯添加量、焙烧温度、总载铬量、助催化剂、聚合温度、压力和氢气等进行了系统地研究。
研究表明,在催化剂制备过程中,比较恰当的BC添加量应为CrBC≤0.25wt%。合适的焙烧温度和总载铬量应分别为<600℃和≤0.5wt%。
在乙烯均聚过程中,适量的烷基铝助催化剂如三乙基铝等,可以提高复合催化剂HCat-2勺活性。乙烯均聚动力学结果表明,在助催化剂的作用下,复合催化剂可能存在两种活性中心,分别是快速形成和快速衰减的活性中心(Site A1口Site A2)以及慢速形成和慢速衰减的活性中心(Site B1和Site B2),可能分别是由单体乙烯和烷基铝助催化剂还原表面两种六价铬前驱体所形成。随着聚合温度从30℃升高到90℃,复合催化剂HCat-2的活性及其产物的平均分子量均先升高后降低。将乙烯压力从0.14MPa升高到0.7MPa则大幅提高了该催化剂的活性。氢气的加入却降低了催化剂HCat-2的活性及其产物的平均分子量。
在乙烯/1-己烯共聚过程中,随着1-己烯用量从0vo1%提高到7vo1%,HCat-2催化剂的活性及其共聚产物中的1-己烯插入率分别呈下降和上升趋势。其共聚物的平均分子量则先升高后降低。共聚动力学结果表明,在助催化剂存在下,复合催化剂体系内可能同样存在上述两种活性中心,其可能分别由单体乙烯、共聚单体1-己烯和烷基铝助催化剂还原表面六价铬物种所形成。通过比较不同铬系催化剂,HCat-2催化剂显示出比S-2催化剂更高的活性。其共聚物具有比Phillips催化剂所产共聚物更高的平均分子量和更宽的分子量分布,且还具有比Phillips和S-2催化剂共聚物略高的1-己烯插入率。
在共聚产物短支链分布的表征方面,首先,本文摸索出一种快速、有效、定性表征高密度聚乙烯样品中短支链分布的方法,即升温淋洗分级联合连续自成核退火方法(temperature rising elution fractionation cross successive self-nucleation annealing, TREF+SSA)。这种方法具有成本低、耗时少的优点。利用该方法,本文比较了Phillips、S-2、 HCat-2和Cat-M四个催化剂小试所产共聚物中的短支链分布。其中Cat-M催化剂是机械混合Phillips和S-2催化剂所制备的。表征结果显示,HCat-2催化剂所产共聚物最高温级分的相对短支链含量与Phillips和Cat-M催化剂共聚产物类似,且比S-2催化剂共聚产物最高温级分的含量略高。而在最低温级分,HCat-2催化剂共聚产物的相对短支链含量最少。这种短支链分布将会有利于高等级高密度聚乙烯管材料的长期使用性能。对该结果的解释可能是由于在复合催化剂共聚过程中,催化剂体系内之前所述的铬活性中心Site A1和Site A2间存在一种协同效用。之后,本文又使用两种不同方法对采用新型复合催化剂的单釜工艺在生产性试验中所生产的两个高密度聚乙烯管材料样品(包括长期使用性能差的PE-1和长期使用性能好的PE-2样品)中的短支链分布进行了比较。其中一种是成本高、耗时长,但相对比较直接、定量的升温淋洗分级联合13碳核磁方法(TREF+13C-NMR)。另一种则是快速、定性的升温淋洗分级联合分步结晶方法(TREF cross step crystallization, TREF+SC)0表征结果显示,PE-2最高温级分(对应最高分子量部分)的相对短支链含量高于PE-1的最高温级分。而在最低温级分(对应最低分子量部分),与上述情况则刚好相反。该结果验证了之前TREF+SSA方法对高密度聚乙烯样品中短支链分布定性表征的正确性和有效性,同时说明样品最高温级分的相对短支链含量越高,以及最低温级分的相对短支链含量越低会越有利于高等级聚乙烯管材料的长期使用性能。因此,新型复合催化剂显示出了良好的综合性能包括聚合活性、共聚能力和产物微结构特别是短支链分布性能。
基于本研究工作的成果包括小试阶段新型复合催化剂的开发和管材料结构性能研究,合作单位中石化齐鲁分公司进一步完成了单釜UNIPOL工艺PE100级管材料专用催化剂的开发和管材料的产业化。截止到本课题所属合作项目(“十一五”科技支撑计划项目2007BAE50B04)结题为止(2010年12月),齐鲁分公司已成功生产出2万余吨单釜工艺的PE100级高等级管材料。该技术在创造了巨大的经济和社会效益的同时,还具备在国内外同类UNIPOL聚乙烯工艺上推广应用的可行性。
Nowadays high grade high density polyethylene (HDPE) pipe material is widely used for the transport of water or gas etc. at high pressure in the field of architecture with an increasing application in the world plastic market. It is manufactured from ethylene/α-olefin (Usually1-butune,1-hexene and1-octene) copolymers using mostly two-stage polymerization processes. However, up to now the technology of the two-stage processes and the catalysts thereof is monopolized by several developed countries. In order to substitute the current two-stage process with high cost and energy consumption, it is a mainstream trend to develop an one-stage process with low cost and energy consumption. However, it still remained as a great challenge in both academic and industrial fields to prepare a novel catalyst system for the one-stage process. In the industrial field, two important polyethylene catalysts namely inorganic Phillips (chromium oxide supported on the silica gel) and organic S-2(Bis(triphenysilyl) chromate supported on the silica gel) catalysts show their unique features on ethylene polymerization and their polyethylene products. In this work, a novel SiO2-supported inorganic and organic hybrid chromium-based catalyst is synthesized using the residual surface hydroxyl groups in Phillips catalyst to further support bis(triphenysilyl) chromate (BC), which is eventually successfully applied to manufacture high grade HDPE pipe material for the one-stage process. The novel hybrid catalyst gets the merits from each catalyst system, especially in the aspect of short chain branches distribution (SCBD) of its copolymer. By the characterization of the catalysts, the investigation of ethylene homopolymerization and ethylene/1-hexene copolymerization behavior and the microstructures of resultant polymers, several vital factors such as the addition amount of BC and1-hexene comonomer, cocatalyst, calcination temperature, total chromium loading, polymerization temperature, pressure and hydrogen etc, which could influence the hybrid catalyst system, were systematically investigated.
During the catalyst preparation, the proper addition weight amount of BC was found to be CrBC≤0.25wt%. The suitable calcination temperature and total chromium loading were≤600℃and≤0.5wt%, respectively.
As for ethylene homopolymerization, the proper dosage of alkyl aluminium cocatalyst such as triethylaluminium etc could enhance the activity of hybrid catalyst namely HCat-2. Kinetic results suggested that there might exist two kinds of Cr active sites in the hybrid catalyst system in the presence of cocatalyst:One was fast formation and fast decay type (Site A1and Site A2), and the other was slow formation and slow decay type (Site B1and Site B2), which might be formed through the reducing of surface chromate species by ethylene monomer and alkyl-Al cocatalyst, respectively. With raising the polymerization temperature from30℃to90℃, the activity of HCat-2catalyst and the average molecular weight (MW) of its polymer first increased and then decreased. Raising the ethylene pressure from0.14MPa to0.7MPa greatly enhanced the activity of HCat-2catalyst. But adding hydrogen decreased the activity of the catalyst and the average MW of its polymer.
In the ethylene/1-hexene copolymerization, with increasing1-hexene from0vol%to7vol%, the activity of HCat-2catalyst and1-hexene incorporation of its copolymers showed a decreasing and an increasing tendency, respectively. The average MW of its copolymer first increased and then decreased. Kinetic results showed that there might still exist the above two kinds of Cr active sites in the hybrid catalyst system in the presence of cocatalyst, which might be formed through the reducing of surface chromate species by ethylene monomer,1-hexene comonomer and alkyl-Al cocatalyst. By comparing different chromium catalysts, HCat-2catalyst showed much higher activity than S-2catalyst. Its copolymer had higher average MW, boarder molecular weight distribution (MWD) than that obtained from Phillips catalyst, and showed slightly higher1-hexene incorporation than those obtained from Phillips and S-2catalysts.
In the aspect of SCBD characterization of resultant copolymers, firstly, a quick, effective and qualitative method for characterizing the SCBD of HDPE samples namely temperature rising elution fractionation cross successive self-nucleation annealing (TREF+SSA) was developed in this work, which needs low cost and short time consumption. By using this method, the SCBD of copolymers obtained from Phillips, S-2, HCat-2and Cat-M catalysts was compared. The Cat-M catalyst was prepared by mechanically mixing the Phillips and S-2catalysts. The results showed that the copolymer obtained from HCat-2catalyst showed similar relative short chain branches (SCBs) content in its highest temperature TREF fraction as those obtained from Phillips and Cat-M catalyst. The SCBs content was slightly higher than that in the highest temperature TREF fraction of the copolymer obtained from S-2catalyst. In contrast, it had the least relative SCBs content in the lowest temperature TREF fraction of the four copolymers. This SCBD might be beneficial for the long term performance of high grade HDPE pipe material. The result might be explained by a synergetic effect between the above Cr active sites namely Site A1and Site A2in the copolymerization with the hybrid catalyst. Thereafter, the SCBD of two industrial test HDPE pipe material samples (PE-1with bad long term performance and PE-2with good long term performance, both made by the hybrid catalyst through industrial test) was compared by two different methods. One was TREF cross13C-NMR (TREF+13C-NMR) as a relatively direct, quantitative method with high cost and long time consumption, and the other was TREF cross step crystallization (TREF+SC) as a quick, qualitative method. The results showed that the relative SCBs content in the highest temperature TREF fraction (corresponding to the highest MW part) of PE-2sample was higher than that of PE-1sample. In contrast, the opposite situation occurred in their lowest temperature TREF fraction (corresponding to the lowest MW part). The results demonstrated the accuracy and effectiveness of the TREF+SSA for characterizing the SCBD of HDPE samples. It also suggested that the higher relative SCBs content in the highest temperature TREF fraction (corresponding to the highest MW part) of HDPE sample, and the lower relative SCBs content in the lowest temperature TREF fraction (corresponding to the lowest MW part) were beneficial for the long term performance of high grade HDPE pipe material. Therefore, the novel hybrid catalyst had well-balanced properties including activity, copolymerization ability and microstructures of its polymer especially SCBD.
Based on our results including the development of a novel catalyst in the bench scale and the investigation of structure-property relationship of the high grade HDPE pipe material, Qilu Branch Co., SINOPEC further accomplished the commercial development of the novel hybrid catalyst for producing PE100pipe material with the one-stage UNIPOL process. Until the end of our joint project (2007BAE50B04)(Dec.31,2010), more than twenty thousand tons of PE100pipe materials using the one-stage process were successfully manufactured by Qilu Branch Co., SINOPEC. This technic creates huge economic and social benefit, and also owns the possibility for a wide application in other UNIPOL processes.
研究表明,在催化剂制备过程中,比较恰当的BC添加量应为CrBC≤0.25wt%。合适的焙烧温度和总载铬量应分别为<600℃和≤0.5wt%。
在乙烯均聚过程中,适量的烷基铝助催化剂如三乙基铝等,可以提高复合催化剂HCat-2勺活性。乙烯均聚动力学结果表明,在助催化剂的作用下,复合催化剂可能存在两种活性中心,分别是快速形成和快速衰减的活性中心(Site A1口Site A2)以及慢速形成和慢速衰减的活性中心(Site B1和Site B2),可能分别是由单体乙烯和烷基铝助催化剂还原表面两种六价铬前驱体所形成。随着聚合温度从30℃升高到90℃,复合催化剂HCat-2的活性及其产物的平均分子量均先升高后降低。将乙烯压力从0.14MPa升高到0.7MPa则大幅提高了该催化剂的活性。氢气的加入却降低了催化剂HCat-2的活性及其产物的平均分子量。
在乙烯/1-己烯共聚过程中,随着1-己烯用量从0vo1%提高到7vo1%,HCat-2催化剂的活性及其共聚产物中的1-己烯插入率分别呈下降和上升趋势。其共聚物的平均分子量则先升高后降低。共聚动力学结果表明,在助催化剂存在下,复合催化剂体系内可能同样存在上述两种活性中心,其可能分别由单体乙烯、共聚单体1-己烯和烷基铝助催化剂还原表面六价铬物种所形成。通过比较不同铬系催化剂,HCat-2催化剂显示出比S-2催化剂更高的活性。其共聚物具有比Phillips催化剂所产共聚物更高的平均分子量和更宽的分子量分布,且还具有比Phillips和S-2催化剂共聚物略高的1-己烯插入率。
在共聚产物短支链分布的表征方面,首先,本文摸索出一种快速、有效、定性表征高密度聚乙烯样品中短支链分布的方法,即升温淋洗分级联合连续自成核退火方法(temperature rising elution fractionation cross successive self-nucleation annealing, TREF+SSA)。这种方法具有成本低、耗时少的优点。利用该方法,本文比较了Phillips、S-2、 HCat-2和Cat-M四个催化剂小试所产共聚物中的短支链分布。其中Cat-M催化剂是机械混合Phillips和S-2催化剂所制备的。表征结果显示,HCat-2催化剂所产共聚物最高温级分的相对短支链含量与Phillips和Cat-M催化剂共聚产物类似,且比S-2催化剂共聚产物最高温级分的含量略高。而在最低温级分,HCat-2催化剂共聚产物的相对短支链含量最少。这种短支链分布将会有利于高等级高密度聚乙烯管材料的长期使用性能。对该结果的解释可能是由于在复合催化剂共聚过程中,催化剂体系内之前所述的铬活性中心Site A1和Site A2间存在一种协同效用。之后,本文又使用两种不同方法对采用新型复合催化剂的单釜工艺在生产性试验中所生产的两个高密度聚乙烯管材料样品(包括长期使用性能差的PE-1和长期使用性能好的PE-2样品)中的短支链分布进行了比较。其中一种是成本高、耗时长,但相对比较直接、定量的升温淋洗分级联合13碳核磁方法(TREF+13C-NMR)。另一种则是快速、定性的升温淋洗分级联合分步结晶方法(TREF cross step crystallization, TREF+SC)0表征结果显示,PE-2最高温级分(对应最高分子量部分)的相对短支链含量高于PE-1的最高温级分。而在最低温级分(对应最低分子量部分),与上述情况则刚好相反。该结果验证了之前TREF+SSA方法对高密度聚乙烯样品中短支链分布定性表征的正确性和有效性,同时说明样品最高温级分的相对短支链含量越高,以及最低温级分的相对短支链含量越低会越有利于高等级聚乙烯管材料的长期使用性能。因此,新型复合催化剂显示出了良好的综合性能包括聚合活性、共聚能力和产物微结构特别是短支链分布性能。
基于本研究工作的成果包括小试阶段新型复合催化剂的开发和管材料结构性能研究,合作单位中石化齐鲁分公司进一步完成了单釜UNIPOL工艺PE100级管材料专用催化剂的开发和管材料的产业化。截止到本课题所属合作项目(“十一五”科技支撑计划项目2007BAE50B04)结题为止(2010年12月),齐鲁分公司已成功生产出2万余吨单釜工艺的PE100级高等级管材料。该技术在创造了巨大的经济和社会效益的同时,还具备在国内外同类UNIPOL聚乙烯工艺上推广应用的可行性。
Nowadays high grade high density polyethylene (HDPE) pipe material is widely used for the transport of water or gas etc. at high pressure in the field of architecture with an increasing application in the world plastic market. It is manufactured from ethylene/α-olefin (Usually1-butune,1-hexene and1-octene) copolymers using mostly two-stage polymerization processes. However, up to now the technology of the two-stage processes and the catalysts thereof is monopolized by several developed countries. In order to substitute the current two-stage process with high cost and energy consumption, it is a mainstream trend to develop an one-stage process with low cost and energy consumption. However, it still remained as a great challenge in both academic and industrial fields to prepare a novel catalyst system for the one-stage process. In the industrial field, two important polyethylene catalysts namely inorganic Phillips (chromium oxide supported on the silica gel) and organic S-2(Bis(triphenysilyl) chromate supported on the silica gel) catalysts show their unique features on ethylene polymerization and their polyethylene products. In this work, a novel SiO2-supported inorganic and organic hybrid chromium-based catalyst is synthesized using the residual surface hydroxyl groups in Phillips catalyst to further support bis(triphenysilyl) chromate (BC), which is eventually successfully applied to manufacture high grade HDPE pipe material for the one-stage process. The novel hybrid catalyst gets the merits from each catalyst system, especially in the aspect of short chain branches distribution (SCBD) of its copolymer. By the characterization of the catalysts, the investigation of ethylene homopolymerization and ethylene/1-hexene copolymerization behavior and the microstructures of resultant polymers, several vital factors such as the addition amount of BC and1-hexene comonomer, cocatalyst, calcination temperature, total chromium loading, polymerization temperature, pressure and hydrogen etc, which could influence the hybrid catalyst system, were systematically investigated.
During the catalyst preparation, the proper addition weight amount of BC was found to be CrBC≤0.25wt%. The suitable calcination temperature and total chromium loading were≤600℃and≤0.5wt%, respectively.
As for ethylene homopolymerization, the proper dosage of alkyl aluminium cocatalyst such as triethylaluminium etc could enhance the activity of hybrid catalyst namely HCat-2. Kinetic results suggested that there might exist two kinds of Cr active sites in the hybrid catalyst system in the presence of cocatalyst:One was fast formation and fast decay type (Site A1and Site A2), and the other was slow formation and slow decay type (Site B1and Site B2), which might be formed through the reducing of surface chromate species by ethylene monomer and alkyl-Al cocatalyst, respectively. With raising the polymerization temperature from30℃to90℃, the activity of HCat-2catalyst and the average molecular weight (MW) of its polymer first increased and then decreased. Raising the ethylene pressure from0.14MPa to0.7MPa greatly enhanced the activity of HCat-2catalyst. But adding hydrogen decreased the activity of the catalyst and the average MW of its polymer.
In the ethylene/1-hexene copolymerization, with increasing1-hexene from0vol%to7vol%, the activity of HCat-2catalyst and1-hexene incorporation of its copolymers showed a decreasing and an increasing tendency, respectively. The average MW of its copolymer first increased and then decreased. Kinetic results showed that there might still exist the above two kinds of Cr active sites in the hybrid catalyst system in the presence of cocatalyst, which might be formed through the reducing of surface chromate species by ethylene monomer,1-hexene comonomer and alkyl-Al cocatalyst. By comparing different chromium catalysts, HCat-2catalyst showed much higher activity than S-2catalyst. Its copolymer had higher average MW, boarder molecular weight distribution (MWD) than that obtained from Phillips catalyst, and showed slightly higher1-hexene incorporation than those obtained from Phillips and S-2catalysts.
In the aspect of SCBD characterization of resultant copolymers, firstly, a quick, effective and qualitative method for characterizing the SCBD of HDPE samples namely temperature rising elution fractionation cross successive self-nucleation annealing (TREF+SSA) was developed in this work, which needs low cost and short time consumption. By using this method, the SCBD of copolymers obtained from Phillips, S-2, HCat-2and Cat-M catalysts was compared. The Cat-M catalyst was prepared by mechanically mixing the Phillips and S-2catalysts. The results showed that the copolymer obtained from HCat-2catalyst showed similar relative short chain branches (SCBs) content in its highest temperature TREF fraction as those obtained from Phillips and Cat-M catalyst. The SCBs content was slightly higher than that in the highest temperature TREF fraction of the copolymer obtained from S-2catalyst. In contrast, it had the least relative SCBs content in the lowest temperature TREF fraction of the four copolymers. This SCBD might be beneficial for the long term performance of high grade HDPE pipe material. The result might be explained by a synergetic effect between the above Cr active sites namely Site A1and Site A2in the copolymerization with the hybrid catalyst. Thereafter, the SCBD of two industrial test HDPE pipe material samples (PE-1with bad long term performance and PE-2with good long term performance, both made by the hybrid catalyst through industrial test) was compared by two different methods. One was TREF cross13C-NMR (TREF+13C-NMR) as a relatively direct, quantitative method with high cost and long time consumption, and the other was TREF cross step crystallization (TREF+SC) as a quick, qualitative method. The results showed that the relative SCBs content in the highest temperature TREF fraction (corresponding to the highest MW part) of PE-2sample was higher than that of PE-1sample. In contrast, the opposite situation occurred in their lowest temperature TREF fraction (corresponding to the lowest MW part). The results demonstrated the accuracy and effectiveness of the TREF+SSA for characterizing the SCBD of HDPE samples. It also suggested that the higher relative SCBs content in the highest temperature TREF fraction (corresponding to the highest MW part) of HDPE sample, and the lower relative SCBs content in the lowest temperature TREF fraction (corresponding to the lowest MW part) were beneficial for the long term performance of high grade HDPE pipe material. Therefore, the novel hybrid catalyst had well-balanced properties including activity, copolymerization ability and microstructures of its polymer especially SCBD.
Based on our results including the development of a novel catalyst in the bench scale and the investigation of structure-property relationship of the high grade HDPE pipe material, Qilu Branch Co., SINOPEC further accomplished the commercial development of the novel hybrid catalyst for producing PE100pipe material with the one-stage UNIPOL process. Until the end of our joint project (2007BAE50B04)(Dec.31,2010), more than twenty thousand tons of PE100pipe materials using the one-stage process were successfully manufactured by Qilu Branch Co., SINOPEC. This technic creates huge economic and social benefit, and also owns the possibility for a wide application in other UNIPOL processes.
引文
[1]王红秋.世界聚乙烯技术的最新进展.中外能源.2008,13(5):83-86
[2]张宝森,孙涛,刘田库.聚乙烯技术进展.辽宁化工.2006,35(9):540-542
[3]段晓芳.聚乙烯催化剂技术进展.国内外石油化工快.2008,38(10):1-9
[4]潘建兴,杨敬一,徐心茹.聚乙烯技术新进展.现代化工.2005,25(8):20-26
[5]M. P. McDaniel. A review of the Phillips supported chromium catalyst and its commercial use for ethylene polymerization, in Advances in Catalysis, C.G. Bruce and K. Helmut, Editors.2010, Academic Press, p.123-606
[6]吴绍鳢,刘华.简述PE100管材的应用与节能优势.甘肃科技.2008,24(16):71-72
[7]M. D. Failla, J. C. Lucas, L. Mandelkern. Supermolecular structure of random copolymers of ethylene. Macromolecules.1994,27(6):1334-1337
[8]M. A. Kennedy, A. J. Peacock, L. Mandelkern. Tensile properties of crystalline polymers: Linear polyethylene. Macromolecules.1994,27(19):5297-5310
[9]K. Jordens, G. L. Wilkes, J. Janzen, D. C. Rohlfing, M. B. Welch. The influence of molecular weight and thermal history on the thermal, rheological, and mechanical properties of metallocene-catalyzed linear polyethylenes. Polymer.2000, 41(19):7175-7192
[10]J. B. P. Soares, R. F. Abbott, J. D. Kim. Environmental stress cracking resistance of polyethylene:The use of CRYSTAF and SEC to establish structure-property relationships. Journal of Polymer Science Part B:Polymer Physics.2000, 38(10):1267-1275
[11]L. Hubert, L. David, R. Seguela, G. Vigier, C. Corfias-Zuccalli, Y. Germain. Physical and mechanical properties of polyethylene for pipes in relation to molecular architecture. II. Short-term creep of isotropic and drawn materials. Journal of Applied Polymer Science. 2002,84(12):2308-2317
[12]P. J. DesLauriers, D. C. Rohlfing, E. T. Hsieh. Quantifying short chain branching microstructures in ethylene 1-olefin copolymers using size exclusion chromatography and Fourier transform infrared spectroscopy (SEC-FTIR). Polymer.2002,43(1):159-170
[13]P. J. DesLauriers, M. P. McDaniel, D. C. Rohlfing, R. K. Krishnaswamy, S. J. Secora, E. A. Benham, P. L. Maeger, A. R. Wolfe, A. M. Sukhadia, B. B. Beaulieu. A comparative study of multimodal vs. bimodal polyethylene pipe resins for PE-100 applications. Polymer Engineering and Science.2005,45(9):1203-1213
[14]P. J. DesLauriers, M. P. McDaniel. Short chain branching profiles in polyethylene from the Phillips Cr/silica catalyst. Journal of Polymer Science Part A:Polymer Chemistry. 2007,45(15):3135-3149
[15]R. K. Krishnaswamy, Q. Yang, L. Fernandez-Ballester, J. A. Kornfield. Effect of the distribution of short-chain branches on crystallization kinetics and mechanical properties of high-density polyethylene. Macromolecules.2008,41(5):1693-1704
[16]J. P. Hogan, R. L. Banks. Start-up of a polymerziation process.1958, US 2860127
[17]J. P. Hogan, R. L. Banks. Stablized catalyst and improved polymerization process.1958, US 2846425
[18]J. P. Hogan, R. L. Banks. Polymer and production thereof.1958, US 2825721
[19]N. Kashiwa. The discovery and progress of MgCl2-supported TiCl4 catalysts. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(1):1-8
[20]W. Kaminsky. The discovery of metallocene catalysts and their present state of the art. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(16):3911-3921
[21]J. A. Ewen. Mechanisms of stereochemical control in propylene polymerizations with soluble Group 4B metallocene/methylalumoxane catalysts. Journal of the American Chemical Society.1984,106(21):6355-6364
[22]B. L. Small, M. Brookhart, A. M. A. Bennett. Highly active iron and cobalt catalysts for the polymerization of ethylene. Journal of the American Chemical Society.1998, 120(16):4049-4050
[23]G. J. P. Britovsek, V. C. Gibson, B. S. Kimberley, P. J. Maddox, S. J. Mctavish, G. A. Solan, A. J. P. White, D. J. Williams. Novel olefin polymerization catalyst based on iron and cobalt. Chemical Communications.1998(7):849-850
[24]J. P. Hogan. Ethylene polymerization catalysis over chromium oxide. Journal of Polymer Science Part A:Polymer Chemistry.1970,8(9):2637-2652
[25]D. S. Kim, J. M. Tatibouet, I. E. Wachs. Surface structure and reactivity of chromium trioxide/silica catalysts. Journal of Catalysis.1992,136(1):209-221
[26]P. C. Thune, J. Loos, A. M. de Jong, P. J. Lemstra, J. W. Niemantsverdriet. Planar model system for olefin polymerization:the Phillips CrOx/SiO2 catalyst. Topics in Catalysis. 2000,13(1-2):67-74
[27]P. C.Thune, J. Loos, D. Wouters, P. J. Lemstra, J. W. Niemantsverdriet. The CrOx/SiO2/Si(100) catalyst-A surface science approach to supported olefin polymerization catalysis. Macromolecular Symposia.2001,173:37-52
[28]P. C. Thune, R. Linke. W. J. H. van Gennip, A. M. de Jong, J. W. Niemantsverdriet. Bonding of supported chromium during thermal activation of the CrOx/SiO2 (Phillips) ethylene polymerization catalyst. Journal of Physical Chemistry B.2001, 105(15):3073-3078
[29]E. Groppo, C. Lamberti, S. Bordiga, G. Spoto, A. Zecchina. The structure of active centers and the ethylene polymerization mechanism on the Cr/SiO2 catalyst:A frontier for the characterization methods. Chemical Reviews.2005,105(1):115-183
[30]C. A. Demmelmaier, R. E. White, J. A. van Bokhoven, S. L. Scott. Evidence for a chromasiloxane ring size effect in Phillips (Cr/SiO2) polymerization catalysts. Journal of Catalysis.2009,262(l):44-56
[31]C. A. Demmelmaier, R. E. White, J. A. van Bokhoven, S. L. Scott. Nature of ==SiOCrO2Cl and (==SiO)2CrO2 sites prepared by grafting CrO2Cl2 onto silica. Journal of Physical Chemistry C.2008,112(16):6439-6449
[32]M. P. McDaniel. Supported chromium catalysts for ethylene polymerization, in Advances in Catalysis, D.D. Eley, H. Pines, and P.B. Weisz, Editors.1985. p.47-98
[33]M. P. McDaniel. The state of chromium(Ⅵ) on the chromium/silica polymerization catalyst. Journal of Catalysis.1981,67(1):71-76
[34]H. L. Krauss, H. Stach. Chromium(Ⅱ) as the active constituent in the Phillips catalyst in ethylene polymerization. Inorganic and Nuclear Chemistry Letters.1968,4(7):393-397
[35]H. L. Krauss, H. Stach. Surface compounds of transition metals. Ⅲ. Reactions of reduced Philips contact catalysts. Zeitschrift fur Anorganische und Allgemeine Chemie.1969, 366(1-2):34-42
[36]R. Merryfield, M. McDaniel, G. Parks. An XPS study of the Philips chromium/silica polymerization catalyst. Journal of Catalysis.1982,77(2):348-359
[37]A. Damin, J. G. Vitillo, G. Ricchiardi, S. Bordiga, C. Lamberti, E. Groppo, A. Zecchina. Modeling CO and N2 adsorption at Cr surface species of Phillips catalyst by hybrid density functionals:Effect of Hartree-Fock exchange percentage. Journal of Physical Chemistry A.2009,113(52):14261-14269
[38]C. N. Nenu, E. Groppo, C. Lamberti, A. M. Beale, T. Visser, A. Zecchina, B. M. Weckhuysen. Dichloromethane as a selective modifying agent to create a family of highly reactive chromium polymerization sites. Angewandte Chemie International Edition.2007,46(9):1465-1468
[39]E. Groppo, J. Estephane, C. Lamberti, G. Spoto, A. Zecchina. Ethylene, propylene and ethylene oxide in situ polymerization on the Cr(II)/SiO2 system:A temperature-and pressure-dependent investigation. Catalysis Today.2007,126(1-2):228-234
[40]E. Groppo, C. Lamberti, F. Cesano, A. Zecchina. On the fraction of CrⅡ sites involved in the C2H4 polymerization on the Cr/SiO2 Phillips catalyst:a quantification by FTIR spectroscopy. Physical Chemistry Chemical Physics.2006,8(21):2453-2456
[41]E. Groppo, C. Lamberti, S. Bordiga, G. Spoto, A. Zecchina. In situ FTIR spectroscopy of key intermediates in the first stages of ethylene polymerization on the Cr/SiO2 Phillips catalyst:Solving the puzzle of the initiation mechanism? Journal of Catalysis.2006, 240(2):172-181
[42]A. Damin, F. Bonino, S. Bordiga, E. Groppo, C. Lamberti, A. Zecchina. Vibrational properties of Cr" Centers on reduced Phillips catalysts highlighted by resonant Raman spectroscopy. ChemPhysChem.2006,7(2):342-344
[43]A. B. Gaspar, L. C. Dieguez. The influence of Cr precursors in the ethylene polymerization on Cr/SiO2 catalysts. Applied Catalysis A:General.2002, 227(1-2):241-254
[44]A. B. Gaspar, J. L. F. Brito, L. C. Dieguez. Characterization of chromium species in catalysts for dehydrogenation and polymerization. Journal of Molecular Catalysis A: Chemical.2003,203(1-2):251-266
[45]A. B. Gaspar, L. C. Dieguez. Reduction and desorption with carbon monoxide in Cr/SiO2 catalysts for ethylene polymerization. Journal of Molecular Catalysis A:Chemical.2004, 219(2):357-362
[46]B. P. Liu, H. Nakatani, M. Terano. New aspects of the induction period of ethene polymerization using Phillips CrOx/SiO2 catalyst probed by XPS, TPD and EPMA. Journal of Molecular Catalysis A:Chemical.2002,184(1-2):387-398
[47]M. P. McDaniel, S. J. Martin. Poisoning studies on chromium/silica.2. Carbon monoxide. Journal of Physical Chemistry.1991,95(8):3289-3293
[48]S. M. Wang, P. J. T. Tait, C. E. Marsden. Phillips-type polymerization catalysts:kinetic behavior and active center determination. Journal of Molecular Catalysis.1991, 65(1-2):237-252
[49]G. Ghiotti, E. Garrone, A. Zecchina. IR investigation of polymerization centers of the Phillips catalyst. Journal of Molecular Catalysis.1988,46(1-3):61-77
[50]S. L. Scott, J. A. N. Ajjou. Surface organometallic investigation of the mechanism of ethylene polymerization by silica-supported Cr catalysts. Chemical Engineering Science. 2001,56(13):4155-4168
[51]D. L. Myers, J. H. Lunsford. Silica-supported chromium catalysts for ethylene polymerization. Journal of Catalysis.1985,92(2):260-271
[52]D. L. Myers, J. H. Lunsford. Silica-supported chromium catalysts for ethylene polymerization:the active oxidation states of chromium. Journal of Catalysis.1986, 99(1):140-148
[53]M. P. McDaniel, M. B. Welch. The activation of the Phillips polymerization catalyst. I. Influence of the hydroxyl population. Journal of Catalysis.1983,82(1):98-109
[54]M. Nishimura, J. M. Thomas. IR study of the interaction of hydroxyl groups of silica gel with chromium species of Phillips' type catalysts. Catalysis Letters.1993, 21(1-2):149-155
[55]M. Nishimura, J. M. Thomas. Probing the early stages of polymerization of ethylene on a model chromium/silica catalyst by Fourier transform infrared spectroscopy. Catalysis Letters.1993,19(1):33-41
[56]O. Espelid, K. J. Borve. Theoretical models of ethylene polymerization over a mononuclear chromium(Ⅱ)/silica site. Journal of Catalysis.2000,195(1):125-139
[57]V. C. F. Holm, A. Clark. Reduction studies on supported metal oxide catalysts. Journal of Catalysis.1968,11:305-316
[58]M. P. McDaniel. Polymerization Reaction, in Handbook of Heterogeneous Catalysis, G. Ertl, et al., Editors.2008, Wiley:Weinheim Germany, p.3733-3792
[59]O. M. Bade, R. Blom, I. M. Dahl, A. Karlsson. A DRIFTS study of the Cr(II)/SiO2 catalyst. Ethylene coordination and early stages of polymerization. Journal of Catalysis. 1998,173(2):460-469
[60]Y. V. Kissin, A. J. Brandolini, J. L. Garlick. Kinetics of ethylene polymerization reactions with chromium oxide catalysts. Journal of Polymer Science Part A:Polymer Chemistry. 2008,46(16):5315-5329
[61]Y. V. Kissin, A. J. Brandolini. Chemistry of olefin polymerization reactions with chromium-based catalysts. Journal of Polymer Science Part A:Polymer Chemistry.2008, 46(16):5330-5347
[62]A. Ellison, T. L. Overton. Characterization of Cr/silica catalysts. Part 2. Ti- and Mg-modified catalysts. Journal of the Chemical Society, Faraday Transactions.1993, 89(24):4393-4395
[63]A. Ellison, T. L. Overton. Characterization of modified Cr-silica catalysts. Journal of Molecular Catalysis.1994,90(1-2):81-86
[64]B. M. Weckhuysen, I. E. Wachs, R. A. Schoonheydt. Surface chemistry and spectroscopy of chromium in inorganic oxides. Chemical Reviews.1996,96(8):3327-3349
[65]B. M. Weckhuysen, I. E. Wachs. In situ Raman spectroscopy of supported chromium oxide catalysts:Reactivity studies with methanol and butane. Journal of Physical Chemistry.1996,100(34):14437-14442
[66]B. M. Weckhuysen, R. A. Schoonheydt, J.-M. Jehna, I. E. Wachs, S. J. Cho, R. Ryoo, S. Kijlstra, E. Poels. Combined DRS-RS-EXAFS-XANES-TPR study of supported chromium catalysts. Journal of the Chemical Society, Faraday Transactions.1995, 91(18):3245-3253
[67]J. N. Finch. Reduction studies on supported chromic anhydride catalysts. Journal of Catalysis.1976,43(1-3):111-121
[68]B. Rebenstorf, T. Lindblad. Amorphous AIPO4 as catalyst support 3. CO FTIR study of AlPO4 impregnated with chromium. Journal of Catalysis.1991,128(2):303-310
[69]M. P. McDaniel, M. M. Johnson. A comparison of Cr/SiO2 and Cr/AlPO4 polymerization catalysts.2. Chain transfer. Macromolecules.1987,20(4):773-778
[70]M. P. McDaniel, M. M. Johnson. A comparison of chromium/silica and chromium/aluminum phosphate polymerization catalysts. Ⅰ. Kinetics. Journal of Catalysis.1986,101(2):446-457
[71]A. B. Gaspar, R. L. Martins, M. Schmal, L. C. Dieguez. Characterization of Cr2+ and ethylene polymerization on Cr/SiO2 catalysts. Journal of Molecular Catalysis A: Chemical.2001,169(1-2):105-112
[72]P. Zielinski, I. G. D. Lana. An FTIR spectroscopic view of the initiation of ethylene polymerization on chromium/silica catalyst. Journal of Catalysis.1992,137(2):368-376
[73]M. Kantcheva, I. G. D. Lana, J. A. Szymura. FTIR spectroscopic investigation of the initiation of ethylene polymerization on Cr/silica. Journal of Catalysis.1995, 154(2):329-334
[74]W. K. Jozwiak, I. G. D. Lana, R. Fiedorow. On the role of surface hydroxyls during the chromium/silica-catalyzed polymerization of ethylene. Journal of Catalysis.1990, 121(1):183-195
[75]M. P. McDaniel, D. M. Cantor. Hydrogen transfer during propagation of the Phillips catalyst. Journal of Polymer Science Part A:Polymer Chemistry.1983,21(4):1217-1221
[76]W. K. Kim, M. J. Fevola, L. M. Liable-Sands, A. L. Rheingold, K. H. Theopold. [(Ph)2nacnac]MCl2(THF)2 (M = Ti, V, Cr):A new class of homogeneous olefin polymerization catalyst featuring beta-diiminate ligands. Organometallics.1998, 17(21):4541-4543
[77]L. A. MacAdams, G. P. Buffone, C. D. Incarvito, A. L. Rheingold, K. H. Theopold. A chromium catalyst for the polymerization of ethylene as a homogeneous model for the Phillips catalyst. Journal of the American Chemical Society.2005,127(4):1082-1083
[78]H. Ikeda, T. Monoi, Y. Sasaki. Performance of the Cr[CH(SiMe3)2]3/Si02 catalyst for ethylene polymerization compared with the performance of the Phillips catalyst. Journal of Polymer Science Part A:Polymer Chemistry.2003,41(3):413-419
[79]T. Monoi, Y. Sasaki. Silica-supported Cr[N(SiMe3)2]3/isobutylalumoxane catalyst for selective ethylene trimerization. Journal of Molecular Catalysis A:Chemical.2002, 187(1):135-141
[80]T. Monoi, H. Ikeda, H. Ohira, Y. Sasaki. Ethylene polymerization with silica-supported Cr[N(SiMe3)2]3/alumoxane catalyst. Polymer Journal.2002,34(6):461-465
[81]J. A. N. Ajjou, S. L. Scott. A kinetic study of ethylene and 1-hexene homo-and copolymerization catalyzed by a silica-supported Cr(IV) complex:Evidence for propagation by a migratory insertion mechanism. Journal of the American Chemical Society.2000,122(37):8968-8976
[82]J. A. N. Ajjou, S. L. Scott, V. Paquet. Synthesis and characterization of silica-stabilized chromium(IV) alkylidene complexes. Journal of the American Chemical Society.1998, 120(2):415-416
[83]J. A. N. Ajjou, G. L. Rice, S. L. Scott. Kinetics and mechanisms of thermally induced alkane eliminations from silica-supported bis(alkyl)chromium(IV) and -vanadium(IV) complexes. Journal of the American Chemical Society.1998,120(51):13436-13443
[84]B. P. Liu, Y. W. Fang, W. Xia, M. Terano. Theoretical investigation of novel silsesquioxane-supported Phillips-type catalyst by density functional theory (DFT) method. Kinetics and Catalysis.2006,47(2):234-240
[85]R. H. Cheng, C. Xu, Z. Liu, Q. Dong, X. L. He, Y. W. Fang, M. Terano, Y. T. Hu, T. J. Pullukat, B. P. Liu. High-resolution spectroscopy (XPS,1H MAS solid-state NMR) and DFT investigations into Ti-modified Phillips CrOx/SiO2 catalysts. Journal of Catalysis. 2010,273(2):103-115
[86]K. Tonosaki, T. Taniike, M. Terano. Origin of broad molecular weight distribution of polyethylene produced by Phillips-type silica-supported chromium catalyst. Journal of Molecular Catalysis A:Chemical.2011,340(1-2):33-38
[87]Z. Liu, L. Zhong, Y. Yang, R. H. Cheng, B. P. Liu. DFT and CASPT2 study on the mechanism of ethylene dimerization over Cr(Ⅱ)OH+ cation. Journal of Physical Chemistry A.2011,115(28):8131-8141
[88]O. Espelid, K. J. Borve. Theoretical analysis of CO adsorption on the reduced Cr/silica system. Journal of Catalysis.2002,205(1):177-190
[89]O. Espelid, K. J. Borve. Molecular-level insight into Cr/silica Phillips-type catalysts: polymerization-active mononuclear chromium sites. Journal of Catalysis.2002, 205(2):366-374
[90]O. Espelid, K. J. E(?)rve. Molecular-level insight into Cr/silica Phillips-Type catalysts: Polymerization-active dinuclear chromium sites. Journal of Catalysis.2002, 206(2):331-338
[91]F. J. Karol, G. L. Karapinka, C. Wu, A. W. Dow, R. N. Johnson, W. L. Carrick. Chromocene catalysts for ethylene polymerization. Scope for polymerization. Journal of Polymer Science Part A:Polymer Chemistry.1972,10(9):2621-2637
[92]M. Hoshino, F. Ebisawa. Low dielectric loss polyethylene polymerized with chromocene catalyst. Journal of Applied Polymer Science.1998,70(3):441-448
[93]M. Schnellbach, F. H. Koehler, J. Bluemel. The Union Carbide catalyst (Cp2Cr + SiO2), studied by solid-state NMR. Journal of Organometallic Chemistry.1996, 520(1-2):227-230
[94]P. J. Ellis, R. W. Joyner, T. Maschmeyer, A. F. Masters, D. A. Niles, A. K. Smith. An EXAFS investigation of chromocene on silica using empirical, semi-empirical and ab initio methods. Journal of Molecular Catalysis A:Chemical.1996, 111(3):297-305
[95]F. J. Karol, S. C. Kao. Ligand effects at transition metal centers for ethylene polymerization. New Journal of Chemistry.1994,18(1):97-103
[96]G. Spoto, A. Zecchina, S. Bordiga, D. Scarano, S. Coluccia. Interaction of chromocene with magnesium oxide and reactivity of the adsorbed species towards carbon monoxide: an IR study. Spectrochimica Acta.1993,49A(9):1235-1245
[97]S. L. Fu, M. P. Rosynek, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.4. Study of ethylene polymerization over chromocene on silica catalysts. Langmuir.1991,7(6):1179-1187
[98]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.3. Interactions of nitrogen oxides with chromocene on silica catalysts. Langmuir.1991,7(6):1172-1178
[99]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.2. The interactions of carbon oxides with chromocene on silica catalysts. Langmuir.1990,6(12):1784-1792
[100]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.1. Characterization of chromocene on silica catalysts. Langmuir.1990, 6(12):1774-1783
[101]A. Zecchina, G. Spoto, S. Bordiga. Interaction of chromocene with the silica surface, and structure of the active species for ethene polymerization. Faraday Discussions of the Chemical Society.1989,87(Catal. Well Charact. Mater.):149-160
[102]C. Otero Arean, E. Escalona Platero, G. Spoto, A. Zecchina. Ethylene polymerization on chromocene supported on gamma -alumina:an FT-IR investigation. Journal of Molecular Catalysis.1989,56(1-3):211-219
[103]A. Noshay, F. J. Karol. Chemical activation of silica supports for chromocene-based polyethylene catalysts, in Transition Metal Catalyzed. Polymerizations:Ziegler-Natta and methathesis, R.P. Quirk, et al., Editors.1988, Cambridge university press:Akron, p. 396-416
[104]F. J. Karol, C. Wu, W. T. Reichle, N. J. Maraschin. Role of silanol groups in formation of supported chromocene catalysts. Journal of Catalysis.1979,60(l):68-76
[105]F. J. Karol, R. N. Johnson. Ethylene polymerization studies with supported cyclopentadienyl, arene, and allyl chromium catalysts. Journal of Polymer Science Part A:Polymer Chemistry.1975,13(7):1607-1617
[106]F. J. Karol, C. S. Wu. Chromocene-based catalysts for ethylene polymerization. Thermal removal of the cyclopentadienyl ligand. Journal of Polymer Science Part A:Polymer Chemistry.1974,12(7):1549-1558
[107]F. J. Karol, G. L. Brown, J. M. Davison. Chromocene-based catalysts for ethylene polymerization. Kinetic parameters. Journal of Polymer Science Part A:Polymer Chemistry.1973,11(2):413-424
[108]W. L. Carrick, R. J. Turbett, F. J. Karol, G. L. Karapinka, A. S. Fox, R. N. Johnson. Ethylene polymerization with supported bis(triphenylsilyl) chromate catalysts. Journal of Polymer Science Part A:Polymer Chemistry.1972,10(9):2609-2620
[109]L. M. Baker, W. L. Carrick. Bistriphenylsilyl chromate. Oxidation of olefins and use in ethylene polymerization. Journal of Organic Chemistry.1970,35(3):774-776
[110]W. L. Carrick, G. L. Karapinka, R. J. Turbett. Polymerization process.1967, US 3324095
[111]L. M. Baker, W. L. Carrick. Olefin polymerization process.1967, CA 759121
[112]L. M. Baker, W. L. Carrick. Olefin polymerization process and catalyst therefor.1967, US 3324101
[113]B. P. Liu, P. Y. Qiu, R. H. Cheng, B. Tumanskii, R. J. Batrice, M. Botoshansky, M. S. Eisen. A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization. Organometallics.2011, 30(8):2144-2148
[114]P. Y. Qiu, R. H. Cheng, Z. Liu, B. P. Liu, B. Tumanskii, M. S. Eisen. Switching from ethylene polymerization to nonselective oligomerization over a homogeneous model catalyst:A triphenylsiloxy complex of chromium(VI). Journal of Organometallic Chemistry.2012,699(0):48-55
[115]K. Cann, M. Apecetche, M. H. Zhang. Comparison of silyl chromate and chromium oxide based olefin polymerization catalysts. Macromolecular Symposia.2004, 213:29-36
[116]K. Cann, M. Apecetche, M. H. Zhang, J. Moorhouse. Production of broad molecular weight polyethylene.2004, WO 2004076494
[117]X. F. Li, R. H. Cheng, J. Luo, Q. Dong, X. L. He, L. Z. Li, Y. L. Yu, J. W. Da, B. P. Liu. Experimental and theoretical studies on ethylene polymerization using SiO2-supported silyl chromate type catalysts prepared by a green method. Journal of Molecular Catalysis A:Chemical.2010,330(1-2):56-65
[118]Y. W. Fang, W. Xia, M. He, B. P. Liu, K. Hasebe, M. Terano. Novel SiO2-supported chromium catalyst bearing new organo-siloxane ligand for ethylene polymerization. Journal of Molecular Catalysis A:Chemical.2006,247(1-2):240-247
[119]M. P. McDaniel. Controlling polymer properties with the Phillips chromium catalysts. Industrial and Engineering Chemistry Research.1988,27(9):1559-1564
[120]E. A. Benham, P. D. Smith, M. P. McDaniel. A process for the simultaneous oligomerization and copolymerization of ethylene. Polymer Engineering and Science. 1988,28(22):1469-1472
[121]A. Kurek, S. Mark, M. Enders, M. O. Kristen, R. Mulhaupt. Mesoporous silica supported multiple single-site catalysts and polyethylene reactor blends with tailor-made trimodal and ultra-broad molecular weight distributions. Macromolecular Rapid Communications.2010,31(15):1359-1363
[122]J. Moreno, R. van Grieken, A. Carrero, B. Paredes. Development of novel chromium oxide/metallocene hybrid catalysts for bimodal polyethylene. Polymer.2011, 52(9):1891-1899
[123]J. Aguado, G. Calleja, A. Carrero, J. Moreno. Morphological modifications of Cr/SBA-15 and Cr/Al-SBA-15 ethylene polymerization catalysts:Influence on catalytic behaviour and polymer properties. Microporous and Mesoporous Materials.2010, 131(1-3):294-302
[124]J. Aguado, G. Calleja, A. Carrero, J. Moreno. One-step synthesis of chromium and aluminium containing SBA-15 materials. New phillips catalysts for ethylene polymerization. Chemical Engineering Journal.2008,137(2):443-452
[125]K. J. Chu, J. B. P. Soares, A. Penlidis, S. K. Ihm. Effect of prepolymerization and hydrogen pressure on the microstructure of ethylene/1-hexene copolymers made with MgCl2-supported TiCl3 catalysts. European Polymer Journal.2000,36(1):3-11
[126]M. Ahmadi, R. Jarnjah, M. Nekoomanesh, G. H. Zohuri, H. Arabi. Ziegler-Natta/metallocene hybrid catalyst for ethylene polymerization. Macromolecular Reaction Engineering.2007, 1(6):604-610
[127]M. R. Seger, G E. Maciel. Quantitative 13C NMR analysis of sequence distributions in poly(ethylene-co-1-hexene). Analytical Chemistry.2004,76(19):5734-5747
[128]W. H. Daudt, J. F. Hyde. Synthesis of methylphenyldisiloxanes. Journal of the American Chemical Society.1952,74(2):386-390
[129]H. Suvi, R. Andrew. The reaction of hexamethyldisilazane and subsequent oxidation of trimethylsilyl groups on silica studied by solid-state NMR and FTIR. Journal of Physical Chemistry.1994,98(6):1695-1703
[130]P. J. DesLauriers, C. Tso, Y. Yu, D. L. Rohlfing, M. P. McDaniel. Long-chain branching in PE from Cr/aluminophosphate catalysts. Applied Catalysis A:General.2010, 388(1-2):102-112
[131]W. Xia, K. Tonosaki, T. Taniike, M. Terano, T. Fujitani, B. P. Liu. Copolymerization of ethylene and cyclopentene with the Phillips CrOx/SiO2 catalyst in the presence of an aluminum alkyl cocatalyst. Journal of Applied Polymer Science.2009, 111(4):1869-1877
[132]W. Xia, B. P. Liu, Y. W. Fang, K. Hasebe, M. Terano. Unique polymerization kinetics obtained from simultaneous interaction of Phillips Cr(VI)Ox/SiO2 catalyst with Al-alkyl cocatalyst and ethylene monomer. Journal of Molecular Catalysis A:Chemical.2006, 256(1-2):301-308
[133]B. P. Liu, P. Sindelar, Y. W. Fang, K. Hasebe, M. Terano. Correlation of oxidation states of surface chromium species with ethylene polymerization activity for Phillips CrOx/SiO2 catalysts modified by Al-alkyl cocatalyst. Journal of Molecular Catalysis A: Chemical.2005,238(1-2):142-150
[134]B. P. Liu, Y. W. Fang, M. Terano. High resolution X-ray photoelectron spectroscopic analysis of transformation of surface chromium species on Phillips CrOx/SiO2 catalysts isothermally calcined at various temperatures. Journal of Molecular Catalysis A: Chemical.2004,219(1):165-173
[135]Y. V. Kissin, L. A. Rishina, E. I. Vizen. Hydrogen effects in propylene polymerization reactions with titanium-based Ziegler-Natta catalysts. Ⅱ. Mechanism of the chain-transfer reaction. Journal of Polymer Science Part A:Polymer Chemistry.2002, 40(11):1899-1911
[136]Y. V. Kissin, L. A. Rishina. Hydrogen effects in propylene polymerization reactions with titanium-based Ziegler-Natta catalysts. I. Chemical mechanism of catalyst activation. Journal of Polymer Science Part A:Polymer Chemistry.2002, 40(9):1353-1365
[137]Y. V. Kissin, R. I. Mink, T. E. Nowlin. Ethylene polymerization reactions with Ziegler-Natta catalysts. I. Ethylene polymerization kinetics and kinetic mechanism. Journal of Polymer Science Part A:Polymer Chemistry.1999,37(23):4255-4272
[138]Y. V. Kissin, A. J. Brandolini. Ethylene polymerization reactions with Ziegler-Natta catalysts. Ⅱ. Ethylene polymerization reactions in the presence of deuterium. Journal of Polymer Science Part A:Polymer Chemistry.1999,37(23):4273-4280
[139]W. Wang, Z. Q. Fan, L. X. Feng, C. H. Li. Substituent effect of bisindenyl zirconene catalyst on ethylene/1-hexene copolymerization and propylene polymerization. European Polymer Journal.2005,41(1):83-89
[140]R. Quijada, A. Narvaez, R. Rojas, F. M. Rabagliati, G. B. Galland, R. S. Mauler, R. Benavente, E. Perez, J. M. Perena, A. Bello. Synthesis and characterization of copolymers of ethylene and 1-octadecene using the rac-Et(Ind)2ZrCl2/MAO catalyst system. Macromolecular Chemistry and Physics.1999,200(6):1306-1310
[141]J. S. Yoon, D. H. Lee, E. S. Park, I. M. Lee, D. K. Park, S. O. Jung. Copolymerization of ethylene/a-olefins over (2-MeInd)2ZrCl2/MAO and (2-BzInd)2ZrCl2/MAO systems. Journal of Applied Polymer Science.2000,75(7):928-937
[142]Y. W. Fang, B. P. Liu, K. Hasebe, M. Terano. Ethylene and 1-hexene copolymerization with CO-prereduced Phillips CrOx/SiO2 catalyst in the presence of Al-alkyl cocatalyst. Journal of Polymer Science Part A:Polymer Chemistry.2005,43(19):4632-4641
[143]K. Weiss, H. L. Krauss. Surface compounds of transition metals,:XXVIII. Polymerization of n-1-alkenes with surface chromium(II) on silica gel support at low temperatures and normal pressure. Journal of Catalysis.1984,88(2):424-430
[144]W. J. Wang, E. Kolodka, S. P. Zhu, A. E. Hamielec, L. K. Kostanski. Temperature rising elution fractionation and characterization of ethylene/octene-1 copolymers synthesized with constrained geometry catalyst. Macromolecular Chemistry and Physics.1999, 200(9):2146-2151
[145]G. B. Galland, R. S. Mauler, L. P. Da Silva, S. Liberman, A. A. Da Silva, R. Quijada. Study of the influence of the reaction parameters on the composition of the metallocene-catalyzed ethylene copolymers using temperature rising elution fractionation and C-13 nuclear magnetic resonance. Journal of Applied Polymer Science.2002,84(1):155-163
[146]Y. D. Fan, Y. H. Xue, W. Nie, X. L. Ji, S. Q. Bo. Characterization of the microstructure of bimodal HDPE resin. Polymer Journal.2009,41(8):622-628
[147]M. Keating, I. H. Lee, C. S. Wong. Thermal fractionation of ethylene polymers in packaging applications. Thermochimica Acta.1996,284(1):47-56
[148]P. Starck, K. Rajanen, B. Logren. Comparative studies of ethylene-α-olefin copolymers by thermal fractionations and temperature-dependent crystallinity measurements. Thermochimica Acta.2003,395(1-2):169-181
[149]F. Chen, R. A. Shanks, G. Amarasinghe. Crystallisation of single-site polyethylene blends investigated by thermal fractionation techniques. Polymer.2001, 42(10):4579-4587
[150]J. Kong, X. D. Fan, Y. C. Xie, W. Q. Qiao. Study on molecular chain heterogeneity of linear low-density polyethylene by cross-fractionation of temperature rising elution fractionation and successive self-nucleation/annealing thermal fractionation. Journal of Applied Polymer Science.2004,94(4):1710-1718
[151]A. J. Miiller, M. L. Arnal. Thermal fractionation of polymers. Progress in Polymer Science.2005,30(5):559-603
[152]D. M. Sarzotti, J. B. P. Soares, L. C. Simon, L. J. D. Britto. Analysis of the chemical composition distribution of ethylene/a-olefin copolymers by solution differential scanning calorimetry:an alternative technique to Crystaf. Polymer.2004, 45(14):4787-4799
[153]K. Czaja, M. Bialek, A. Utrata. Copolymerization of ethylene with 1-hexene over metallocene catalyst supported on complex of magnesium chloride with tetrahydrofuran. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(10):2512-2519
[154]A. Miiller, Z. Hernandez, M. Arnal, J. Sanchez. Successive self-nucleation/annealing (SSA):A novel technique to study molecular segregation during crystallization. Polymer Bulletin.1997,39(4):465-472
[155]C. J. Neves, E. Monteiro, A. C. Habert. Characterization of fractionated LLDPE by DSC, FTIR, and SEC. Journal of Applied Polymer Science.1993,50(5):817-824
[156]S. Hosoda, A. Uemura. Effect of the structural distribution on the mechanical properties of linear low-density polyethylenes. Polymer Journal.1992,24(9):939-949
[157]E. Adisson, M. Ribeiro, A. Deffieux, M. Fontanille. Evaluation of the heterogeneity in linear low-density polyethylene comonomer unit distribution by differential scanning calorimetry characterization of thermally treated samples. Polymer.1992, 33(20):4337-4342
[158]S. Hosoda. Structural distribution of linear low-density polyethylenes. Polymer Journal. 1988,20(5):383-397
[159]H. J. Assumption, J. P. Vermeulen, W. L. Jarrett, L. J. Mathias, A. J. van Reenen. High resolution solution and solid state NMR characterization of ethyl ene/1-butene and ethyl ene/1-hexene copolymers fractionated by preparative temperature rising elution fractionation. Polymer.2006,47(1):67-74
[160]J. T. Xu, L. X. Feng. Application of temperature rising elution fractionation in polyolefins. European Polymer Journal.2000,36(5):867-878
[2]张宝森,孙涛,刘田库.聚乙烯技术进展.辽宁化工.2006,35(9):540-542
[3]段晓芳.聚乙烯催化剂技术进展.国内外石油化工快.2008,38(10):1-9
[4]潘建兴,杨敬一,徐心茹.聚乙烯技术新进展.现代化工.2005,25(8):20-26
[5]M. P. McDaniel. A review of the Phillips supported chromium catalyst and its commercial use for ethylene polymerization, in Advances in Catalysis, C.G. Bruce and K. Helmut, Editors.2010, Academic Press, p.123-606
[6]吴绍鳢,刘华.简述PE100管材的应用与节能优势.甘肃科技.2008,24(16):71-72
[7]M. D. Failla, J. C. Lucas, L. Mandelkern. Supermolecular structure of random copolymers of ethylene. Macromolecules.1994,27(6):1334-1337
[8]M. A. Kennedy, A. J. Peacock, L. Mandelkern. Tensile properties of crystalline polymers: Linear polyethylene. Macromolecules.1994,27(19):5297-5310
[9]K. Jordens, G. L. Wilkes, J. Janzen, D. C. Rohlfing, M. B. Welch. The influence of molecular weight and thermal history on the thermal, rheological, and mechanical properties of metallocene-catalyzed linear polyethylenes. Polymer.2000, 41(19):7175-7192
[10]J. B. P. Soares, R. F. Abbott, J. D. Kim. Environmental stress cracking resistance of polyethylene:The use of CRYSTAF and SEC to establish structure-property relationships. Journal of Polymer Science Part B:Polymer Physics.2000, 38(10):1267-1275
[11]L. Hubert, L. David, R. Seguela, G. Vigier, C. Corfias-Zuccalli, Y. Germain. Physical and mechanical properties of polyethylene for pipes in relation to molecular architecture. II. Short-term creep of isotropic and drawn materials. Journal of Applied Polymer Science. 2002,84(12):2308-2317
[12]P. J. DesLauriers, D. C. Rohlfing, E. T. Hsieh. Quantifying short chain branching microstructures in ethylene 1-olefin copolymers using size exclusion chromatography and Fourier transform infrared spectroscopy (SEC-FTIR). Polymer.2002,43(1):159-170
[13]P. J. DesLauriers, M. P. McDaniel, D. C. Rohlfing, R. K. Krishnaswamy, S. J. Secora, E. A. Benham, P. L. Maeger, A. R. Wolfe, A. M. Sukhadia, B. B. Beaulieu. A comparative study of multimodal vs. bimodal polyethylene pipe resins for PE-100 applications. Polymer Engineering and Science.2005,45(9):1203-1213
[14]P. J. DesLauriers, M. P. McDaniel. Short chain branching profiles in polyethylene from the Phillips Cr/silica catalyst. Journal of Polymer Science Part A:Polymer Chemistry. 2007,45(15):3135-3149
[15]R. K. Krishnaswamy, Q. Yang, L. Fernandez-Ballester, J. A. Kornfield. Effect of the distribution of short-chain branches on crystallization kinetics and mechanical properties of high-density polyethylene. Macromolecules.2008,41(5):1693-1704
[16]J. P. Hogan, R. L. Banks. Start-up of a polymerziation process.1958, US 2860127
[17]J. P. Hogan, R. L. Banks. Stablized catalyst and improved polymerization process.1958, US 2846425
[18]J. P. Hogan, R. L. Banks. Polymer and production thereof.1958, US 2825721
[19]N. Kashiwa. The discovery and progress of MgCl2-supported TiCl4 catalysts. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(1):1-8
[20]W. Kaminsky. The discovery of metallocene catalysts and their present state of the art. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(16):3911-3921
[21]J. A. Ewen. Mechanisms of stereochemical control in propylene polymerizations with soluble Group 4B metallocene/methylalumoxane catalysts. Journal of the American Chemical Society.1984,106(21):6355-6364
[22]B. L. Small, M. Brookhart, A. M. A. Bennett. Highly active iron and cobalt catalysts for the polymerization of ethylene. Journal of the American Chemical Society.1998, 120(16):4049-4050
[23]G. J. P. Britovsek, V. C. Gibson, B. S. Kimberley, P. J. Maddox, S. J. Mctavish, G. A. Solan, A. J. P. White, D. J. Williams. Novel olefin polymerization catalyst based on iron and cobalt. Chemical Communications.1998(7):849-850
[24]J. P. Hogan. Ethylene polymerization catalysis over chromium oxide. Journal of Polymer Science Part A:Polymer Chemistry.1970,8(9):2637-2652
[25]D. S. Kim, J. M. Tatibouet, I. E. Wachs. Surface structure and reactivity of chromium trioxide/silica catalysts. Journal of Catalysis.1992,136(1):209-221
[26]P. C. Thune, J. Loos, A. M. de Jong, P. J. Lemstra, J. W. Niemantsverdriet. Planar model system for olefin polymerization:the Phillips CrOx/SiO2 catalyst. Topics in Catalysis. 2000,13(1-2):67-74
[27]P. C.Thune, J. Loos, D. Wouters, P. J. Lemstra, J. W. Niemantsverdriet. The CrOx/SiO2/Si(100) catalyst-A surface science approach to supported olefin polymerization catalysis. Macromolecular Symposia.2001,173:37-52
[28]P. C. Thune, R. Linke. W. J. H. van Gennip, A. M. de Jong, J. W. Niemantsverdriet. Bonding of supported chromium during thermal activation of the CrOx/SiO2 (Phillips) ethylene polymerization catalyst. Journal of Physical Chemistry B.2001, 105(15):3073-3078
[29]E. Groppo, C. Lamberti, S. Bordiga, G. Spoto, A. Zecchina. The structure of active centers and the ethylene polymerization mechanism on the Cr/SiO2 catalyst:A frontier for the characterization methods. Chemical Reviews.2005,105(1):115-183
[30]C. A. Demmelmaier, R. E. White, J. A. van Bokhoven, S. L. Scott. Evidence for a chromasiloxane ring size effect in Phillips (Cr/SiO2) polymerization catalysts. Journal of Catalysis.2009,262(l):44-56
[31]C. A. Demmelmaier, R. E. White, J. A. van Bokhoven, S. L. Scott. Nature of ==SiOCrO2Cl and (==SiO)2CrO2 sites prepared by grafting CrO2Cl2 onto silica. Journal of Physical Chemistry C.2008,112(16):6439-6449
[32]M. P. McDaniel. Supported chromium catalysts for ethylene polymerization, in Advances in Catalysis, D.D. Eley, H. Pines, and P.B. Weisz, Editors.1985. p.47-98
[33]M. P. McDaniel. The state of chromium(Ⅵ) on the chromium/silica polymerization catalyst. Journal of Catalysis.1981,67(1):71-76
[34]H. L. Krauss, H. Stach. Chromium(Ⅱ) as the active constituent in the Phillips catalyst in ethylene polymerization. Inorganic and Nuclear Chemistry Letters.1968,4(7):393-397
[35]H. L. Krauss, H. Stach. Surface compounds of transition metals. Ⅲ. Reactions of reduced Philips contact catalysts. Zeitschrift fur Anorganische und Allgemeine Chemie.1969, 366(1-2):34-42
[36]R. Merryfield, M. McDaniel, G. Parks. An XPS study of the Philips chromium/silica polymerization catalyst. Journal of Catalysis.1982,77(2):348-359
[37]A. Damin, J. G. Vitillo, G. Ricchiardi, S. Bordiga, C. Lamberti, E. Groppo, A. Zecchina. Modeling CO and N2 adsorption at Cr surface species of Phillips catalyst by hybrid density functionals:Effect of Hartree-Fock exchange percentage. Journal of Physical Chemistry A.2009,113(52):14261-14269
[38]C. N. Nenu, E. Groppo, C. Lamberti, A. M. Beale, T. Visser, A. Zecchina, B. M. Weckhuysen. Dichloromethane as a selective modifying agent to create a family of highly reactive chromium polymerization sites. Angewandte Chemie International Edition.2007,46(9):1465-1468
[39]E. Groppo, J. Estephane, C. Lamberti, G. Spoto, A. Zecchina. Ethylene, propylene and ethylene oxide in situ polymerization on the Cr(II)/SiO2 system:A temperature-and pressure-dependent investigation. Catalysis Today.2007,126(1-2):228-234
[40]E. Groppo, C. Lamberti, F. Cesano, A. Zecchina. On the fraction of CrⅡ sites involved in the C2H4 polymerization on the Cr/SiO2 Phillips catalyst:a quantification by FTIR spectroscopy. Physical Chemistry Chemical Physics.2006,8(21):2453-2456
[41]E. Groppo, C. Lamberti, S. Bordiga, G. Spoto, A. Zecchina. In situ FTIR spectroscopy of key intermediates in the first stages of ethylene polymerization on the Cr/SiO2 Phillips catalyst:Solving the puzzle of the initiation mechanism? Journal of Catalysis.2006, 240(2):172-181
[42]A. Damin, F. Bonino, S. Bordiga, E. Groppo, C. Lamberti, A. Zecchina. Vibrational properties of Cr" Centers on reduced Phillips catalysts highlighted by resonant Raman spectroscopy. ChemPhysChem.2006,7(2):342-344
[43]A. B. Gaspar, L. C. Dieguez. The influence of Cr precursors in the ethylene polymerization on Cr/SiO2 catalysts. Applied Catalysis A:General.2002, 227(1-2):241-254
[44]A. B. Gaspar, J. L. F. Brito, L. C. Dieguez. Characterization of chromium species in catalysts for dehydrogenation and polymerization. Journal of Molecular Catalysis A: Chemical.2003,203(1-2):251-266
[45]A. B. Gaspar, L. C. Dieguez. Reduction and desorption with carbon monoxide in Cr/SiO2 catalysts for ethylene polymerization. Journal of Molecular Catalysis A:Chemical.2004, 219(2):357-362
[46]B. P. Liu, H. Nakatani, M. Terano. New aspects of the induction period of ethene polymerization using Phillips CrOx/SiO2 catalyst probed by XPS, TPD and EPMA. Journal of Molecular Catalysis A:Chemical.2002,184(1-2):387-398
[47]M. P. McDaniel, S. J. Martin. Poisoning studies on chromium/silica.2. Carbon monoxide. Journal of Physical Chemistry.1991,95(8):3289-3293
[48]S. M. Wang, P. J. T. Tait, C. E. Marsden. Phillips-type polymerization catalysts:kinetic behavior and active center determination. Journal of Molecular Catalysis.1991, 65(1-2):237-252
[49]G. Ghiotti, E. Garrone, A. Zecchina. IR investigation of polymerization centers of the Phillips catalyst. Journal of Molecular Catalysis.1988,46(1-3):61-77
[50]S. L. Scott, J. A. N. Ajjou. Surface organometallic investigation of the mechanism of ethylene polymerization by silica-supported Cr catalysts. Chemical Engineering Science. 2001,56(13):4155-4168
[51]D. L. Myers, J. H. Lunsford. Silica-supported chromium catalysts for ethylene polymerization. Journal of Catalysis.1985,92(2):260-271
[52]D. L. Myers, J. H. Lunsford. Silica-supported chromium catalysts for ethylene polymerization:the active oxidation states of chromium. Journal of Catalysis.1986, 99(1):140-148
[53]M. P. McDaniel, M. B. Welch. The activation of the Phillips polymerization catalyst. I. Influence of the hydroxyl population. Journal of Catalysis.1983,82(1):98-109
[54]M. Nishimura, J. M. Thomas. IR study of the interaction of hydroxyl groups of silica gel with chromium species of Phillips' type catalysts. Catalysis Letters.1993, 21(1-2):149-155
[55]M. Nishimura, J. M. Thomas. Probing the early stages of polymerization of ethylene on a model chromium/silica catalyst by Fourier transform infrared spectroscopy. Catalysis Letters.1993,19(1):33-41
[56]O. Espelid, K. J. Borve. Theoretical models of ethylene polymerization over a mononuclear chromium(Ⅱ)/silica site. Journal of Catalysis.2000,195(1):125-139
[57]V. C. F. Holm, A. Clark. Reduction studies on supported metal oxide catalysts. Journal of Catalysis.1968,11:305-316
[58]M. P. McDaniel. Polymerization Reaction, in Handbook of Heterogeneous Catalysis, G. Ertl, et al., Editors.2008, Wiley:Weinheim Germany, p.3733-3792
[59]O. M. Bade, R. Blom, I. M. Dahl, A. Karlsson. A DRIFTS study of the Cr(II)/SiO2 catalyst. Ethylene coordination and early stages of polymerization. Journal of Catalysis. 1998,173(2):460-469
[60]Y. V. Kissin, A. J. Brandolini, J. L. Garlick. Kinetics of ethylene polymerization reactions with chromium oxide catalysts. Journal of Polymer Science Part A:Polymer Chemistry. 2008,46(16):5315-5329
[61]Y. V. Kissin, A. J. Brandolini. Chemistry of olefin polymerization reactions with chromium-based catalysts. Journal of Polymer Science Part A:Polymer Chemistry.2008, 46(16):5330-5347
[62]A. Ellison, T. L. Overton. Characterization of Cr/silica catalysts. Part 2. Ti- and Mg-modified catalysts. Journal of the Chemical Society, Faraday Transactions.1993, 89(24):4393-4395
[63]A. Ellison, T. L. Overton. Characterization of modified Cr-silica catalysts. Journal of Molecular Catalysis.1994,90(1-2):81-86
[64]B. M. Weckhuysen, I. E. Wachs, R. A. Schoonheydt. Surface chemistry and spectroscopy of chromium in inorganic oxides. Chemical Reviews.1996,96(8):3327-3349
[65]B. M. Weckhuysen, I. E. Wachs. In situ Raman spectroscopy of supported chromium oxide catalysts:Reactivity studies with methanol and butane. Journal of Physical Chemistry.1996,100(34):14437-14442
[66]B. M. Weckhuysen, R. A. Schoonheydt, J.-M. Jehna, I. E. Wachs, S. J. Cho, R. Ryoo, S. Kijlstra, E. Poels. Combined DRS-RS-EXAFS-XANES-TPR study of supported chromium catalysts. Journal of the Chemical Society, Faraday Transactions.1995, 91(18):3245-3253
[67]J. N. Finch. Reduction studies on supported chromic anhydride catalysts. Journal of Catalysis.1976,43(1-3):111-121
[68]B. Rebenstorf, T. Lindblad. Amorphous AIPO4 as catalyst support 3. CO FTIR study of AlPO4 impregnated with chromium. Journal of Catalysis.1991,128(2):303-310
[69]M. P. McDaniel, M. M. Johnson. A comparison of Cr/SiO2 and Cr/AlPO4 polymerization catalysts.2. Chain transfer. Macromolecules.1987,20(4):773-778
[70]M. P. McDaniel, M. M. Johnson. A comparison of chromium/silica and chromium/aluminum phosphate polymerization catalysts. Ⅰ. Kinetics. Journal of Catalysis.1986,101(2):446-457
[71]A. B. Gaspar, R. L. Martins, M. Schmal, L. C. Dieguez. Characterization of Cr2+ and ethylene polymerization on Cr/SiO2 catalysts. Journal of Molecular Catalysis A: Chemical.2001,169(1-2):105-112
[72]P. Zielinski, I. G. D. Lana. An FTIR spectroscopic view of the initiation of ethylene polymerization on chromium/silica catalyst. Journal of Catalysis.1992,137(2):368-376
[73]M. Kantcheva, I. G. D. Lana, J. A. Szymura. FTIR spectroscopic investigation of the initiation of ethylene polymerization on Cr/silica. Journal of Catalysis.1995, 154(2):329-334
[74]W. K. Jozwiak, I. G. D. Lana, R. Fiedorow. On the role of surface hydroxyls during the chromium/silica-catalyzed polymerization of ethylene. Journal of Catalysis.1990, 121(1):183-195
[75]M. P. McDaniel, D. M. Cantor. Hydrogen transfer during propagation of the Phillips catalyst. Journal of Polymer Science Part A:Polymer Chemistry.1983,21(4):1217-1221
[76]W. K. Kim, M. J. Fevola, L. M. Liable-Sands, A. L. Rheingold, K. H. Theopold. [(Ph)2nacnac]MCl2(THF)2 (M = Ti, V, Cr):A new class of homogeneous olefin polymerization catalyst featuring beta-diiminate ligands. Organometallics.1998, 17(21):4541-4543
[77]L. A. MacAdams, G. P. Buffone, C. D. Incarvito, A. L. Rheingold, K. H. Theopold. A chromium catalyst for the polymerization of ethylene as a homogeneous model for the Phillips catalyst. Journal of the American Chemical Society.2005,127(4):1082-1083
[78]H. Ikeda, T. Monoi, Y. Sasaki. Performance of the Cr[CH(SiMe3)2]3/Si02 catalyst for ethylene polymerization compared with the performance of the Phillips catalyst. Journal of Polymer Science Part A:Polymer Chemistry.2003,41(3):413-419
[79]T. Monoi, Y. Sasaki. Silica-supported Cr[N(SiMe3)2]3/isobutylalumoxane catalyst for selective ethylene trimerization. Journal of Molecular Catalysis A:Chemical.2002, 187(1):135-141
[80]T. Monoi, H. Ikeda, H. Ohira, Y. Sasaki. Ethylene polymerization with silica-supported Cr[N(SiMe3)2]3/alumoxane catalyst. Polymer Journal.2002,34(6):461-465
[81]J. A. N. Ajjou, S. L. Scott. A kinetic study of ethylene and 1-hexene homo-and copolymerization catalyzed by a silica-supported Cr(IV) complex:Evidence for propagation by a migratory insertion mechanism. Journal of the American Chemical Society.2000,122(37):8968-8976
[82]J. A. N. Ajjou, S. L. Scott, V. Paquet. Synthesis and characterization of silica-stabilized chromium(IV) alkylidene complexes. Journal of the American Chemical Society.1998, 120(2):415-416
[83]J. A. N. Ajjou, G. L. Rice, S. L. Scott. Kinetics and mechanisms of thermally induced alkane eliminations from silica-supported bis(alkyl)chromium(IV) and -vanadium(IV) complexes. Journal of the American Chemical Society.1998,120(51):13436-13443
[84]B. P. Liu, Y. W. Fang, W. Xia, M. Terano. Theoretical investigation of novel silsesquioxane-supported Phillips-type catalyst by density functional theory (DFT) method. Kinetics and Catalysis.2006,47(2):234-240
[85]R. H. Cheng, C. Xu, Z. Liu, Q. Dong, X. L. He, Y. W. Fang, M. Terano, Y. T. Hu, T. J. Pullukat, B. P. Liu. High-resolution spectroscopy (XPS,1H MAS solid-state NMR) and DFT investigations into Ti-modified Phillips CrOx/SiO2 catalysts. Journal of Catalysis. 2010,273(2):103-115
[86]K. Tonosaki, T. Taniike, M. Terano. Origin of broad molecular weight distribution of polyethylene produced by Phillips-type silica-supported chromium catalyst. Journal of Molecular Catalysis A:Chemical.2011,340(1-2):33-38
[87]Z. Liu, L. Zhong, Y. Yang, R. H. Cheng, B. P. Liu. DFT and CASPT2 study on the mechanism of ethylene dimerization over Cr(Ⅱ)OH+ cation. Journal of Physical Chemistry A.2011,115(28):8131-8141
[88]O. Espelid, K. J. Borve. Theoretical analysis of CO adsorption on the reduced Cr/silica system. Journal of Catalysis.2002,205(1):177-190
[89]O. Espelid, K. J. Borve. Molecular-level insight into Cr/silica Phillips-type catalysts: polymerization-active mononuclear chromium sites. Journal of Catalysis.2002, 205(2):366-374
[90]O. Espelid, K. J. E(?)rve. Molecular-level insight into Cr/silica Phillips-Type catalysts: Polymerization-active dinuclear chromium sites. Journal of Catalysis.2002, 206(2):331-338
[91]F. J. Karol, G. L. Karapinka, C. Wu, A. W. Dow, R. N. Johnson, W. L. Carrick. Chromocene catalysts for ethylene polymerization. Scope for polymerization. Journal of Polymer Science Part A:Polymer Chemistry.1972,10(9):2621-2637
[92]M. Hoshino, F. Ebisawa. Low dielectric loss polyethylene polymerized with chromocene catalyst. Journal of Applied Polymer Science.1998,70(3):441-448
[93]M. Schnellbach, F. H. Koehler, J. Bluemel. The Union Carbide catalyst (Cp2Cr + SiO2), studied by solid-state NMR. Journal of Organometallic Chemistry.1996, 520(1-2):227-230
[94]P. J. Ellis, R. W. Joyner, T. Maschmeyer, A. F. Masters, D. A. Niles, A. K. Smith. An EXAFS investigation of chromocene on silica using empirical, semi-empirical and ab initio methods. Journal of Molecular Catalysis A:Chemical.1996, 111(3):297-305
[95]F. J. Karol, S. C. Kao. Ligand effects at transition metal centers for ethylene polymerization. New Journal of Chemistry.1994,18(1):97-103
[96]G. Spoto, A. Zecchina, S. Bordiga, D. Scarano, S. Coluccia. Interaction of chromocene with magnesium oxide and reactivity of the adsorbed species towards carbon monoxide: an IR study. Spectrochimica Acta.1993,49A(9):1235-1245
[97]S. L. Fu, M. P. Rosynek, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.4. Study of ethylene polymerization over chromocene on silica catalysts. Langmuir.1991,7(6):1179-1187
[98]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.3. Interactions of nitrogen oxides with chromocene on silica catalysts. Langmuir.1991,7(6):1172-1178
[99]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.2. The interactions of carbon oxides with chromocene on silica catalysts. Langmuir.1990,6(12):1784-1792
[100]S. L. Fu, J. H. Lunsford. Chemistry of organochromium complexes on inorganic oxide supports.1. Characterization of chromocene on silica catalysts. Langmuir.1990, 6(12):1774-1783
[101]A. Zecchina, G. Spoto, S. Bordiga. Interaction of chromocene with the silica surface, and structure of the active species for ethene polymerization. Faraday Discussions of the Chemical Society.1989,87(Catal. Well Charact. Mater.):149-160
[102]C. Otero Arean, E. Escalona Platero, G. Spoto, A. Zecchina. Ethylene polymerization on chromocene supported on gamma -alumina:an FT-IR investigation. Journal of Molecular Catalysis.1989,56(1-3):211-219
[103]A. Noshay, F. J. Karol. Chemical activation of silica supports for chromocene-based polyethylene catalysts, in Transition Metal Catalyzed. Polymerizations:Ziegler-Natta and methathesis, R.P. Quirk, et al., Editors.1988, Cambridge university press:Akron, p. 396-416
[104]F. J. Karol, C. Wu, W. T. Reichle, N. J. Maraschin. Role of silanol groups in formation of supported chromocene catalysts. Journal of Catalysis.1979,60(l):68-76
[105]F. J. Karol, R. N. Johnson. Ethylene polymerization studies with supported cyclopentadienyl, arene, and allyl chromium catalysts. Journal of Polymer Science Part A:Polymer Chemistry.1975,13(7):1607-1617
[106]F. J. Karol, C. S. Wu. Chromocene-based catalysts for ethylene polymerization. Thermal removal of the cyclopentadienyl ligand. Journal of Polymer Science Part A:Polymer Chemistry.1974,12(7):1549-1558
[107]F. J. Karol, G. L. Brown, J. M. Davison. Chromocene-based catalysts for ethylene polymerization. Kinetic parameters. Journal of Polymer Science Part A:Polymer Chemistry.1973,11(2):413-424
[108]W. L. Carrick, R. J. Turbett, F. J. Karol, G. L. Karapinka, A. S. Fox, R. N. Johnson. Ethylene polymerization with supported bis(triphenylsilyl) chromate catalysts. Journal of Polymer Science Part A:Polymer Chemistry.1972,10(9):2609-2620
[109]L. M. Baker, W. L. Carrick. Bistriphenylsilyl chromate. Oxidation of olefins and use in ethylene polymerization. Journal of Organic Chemistry.1970,35(3):774-776
[110]W. L. Carrick, G. L. Karapinka, R. J. Turbett. Polymerization process.1967, US 3324095
[111]L. M. Baker, W. L. Carrick. Olefin polymerization process.1967, CA 759121
[112]L. M. Baker, W. L. Carrick. Olefin polymerization process and catalyst therefor.1967, US 3324101
[113]B. P. Liu, P. Y. Qiu, R. H. Cheng, B. Tumanskii, R. J. Batrice, M. Botoshansky, M. S. Eisen. A triphenylsiloxy complex of chromium(II) as a switchable catalyst for ethylene polymerization and nonselective oligomerization. Organometallics.2011, 30(8):2144-2148
[114]P. Y. Qiu, R. H. Cheng, Z. Liu, B. P. Liu, B. Tumanskii, M. S. Eisen. Switching from ethylene polymerization to nonselective oligomerization over a homogeneous model catalyst:A triphenylsiloxy complex of chromium(VI). Journal of Organometallic Chemistry.2012,699(0):48-55
[115]K. Cann, M. Apecetche, M. H. Zhang. Comparison of silyl chromate and chromium oxide based olefin polymerization catalysts. Macromolecular Symposia.2004, 213:29-36
[116]K. Cann, M. Apecetche, M. H. Zhang, J. Moorhouse. Production of broad molecular weight polyethylene.2004, WO 2004076494
[117]X. F. Li, R. H. Cheng, J. Luo, Q. Dong, X. L. He, L. Z. Li, Y. L. Yu, J. W. Da, B. P. Liu. Experimental and theoretical studies on ethylene polymerization using SiO2-supported silyl chromate type catalysts prepared by a green method. Journal of Molecular Catalysis A:Chemical.2010,330(1-2):56-65
[118]Y. W. Fang, W. Xia, M. He, B. P. Liu, K. Hasebe, M. Terano. Novel SiO2-supported chromium catalyst bearing new organo-siloxane ligand for ethylene polymerization. Journal of Molecular Catalysis A:Chemical.2006,247(1-2):240-247
[119]M. P. McDaniel. Controlling polymer properties with the Phillips chromium catalysts. Industrial and Engineering Chemistry Research.1988,27(9):1559-1564
[120]E. A. Benham, P. D. Smith, M. P. McDaniel. A process for the simultaneous oligomerization and copolymerization of ethylene. Polymer Engineering and Science. 1988,28(22):1469-1472
[121]A. Kurek, S. Mark, M. Enders, M. O. Kristen, R. Mulhaupt. Mesoporous silica supported multiple single-site catalysts and polyethylene reactor blends with tailor-made trimodal and ultra-broad molecular weight distributions. Macromolecular Rapid Communications.2010,31(15):1359-1363
[122]J. Moreno, R. van Grieken, A. Carrero, B. Paredes. Development of novel chromium oxide/metallocene hybrid catalysts for bimodal polyethylene. Polymer.2011, 52(9):1891-1899
[123]J. Aguado, G. Calleja, A. Carrero, J. Moreno. Morphological modifications of Cr/SBA-15 and Cr/Al-SBA-15 ethylene polymerization catalysts:Influence on catalytic behaviour and polymer properties. Microporous and Mesoporous Materials.2010, 131(1-3):294-302
[124]J. Aguado, G. Calleja, A. Carrero, J. Moreno. One-step synthesis of chromium and aluminium containing SBA-15 materials. New phillips catalysts for ethylene polymerization. Chemical Engineering Journal.2008,137(2):443-452
[125]K. J. Chu, J. B. P. Soares, A. Penlidis, S. K. Ihm. Effect of prepolymerization and hydrogen pressure on the microstructure of ethylene/1-hexene copolymers made with MgCl2-supported TiCl3 catalysts. European Polymer Journal.2000,36(1):3-11
[126]M. Ahmadi, R. Jarnjah, M. Nekoomanesh, G. H. Zohuri, H. Arabi. Ziegler-Natta/metallocene hybrid catalyst for ethylene polymerization. Macromolecular Reaction Engineering.2007, 1(6):604-610
[127]M. R. Seger, G E. Maciel. Quantitative 13C NMR analysis of sequence distributions in poly(ethylene-co-1-hexene). Analytical Chemistry.2004,76(19):5734-5747
[128]W. H. Daudt, J. F. Hyde. Synthesis of methylphenyldisiloxanes. Journal of the American Chemical Society.1952,74(2):386-390
[129]H. Suvi, R. Andrew. The reaction of hexamethyldisilazane and subsequent oxidation of trimethylsilyl groups on silica studied by solid-state NMR and FTIR. Journal of Physical Chemistry.1994,98(6):1695-1703
[130]P. J. DesLauriers, C. Tso, Y. Yu, D. L. Rohlfing, M. P. McDaniel. Long-chain branching in PE from Cr/aluminophosphate catalysts. Applied Catalysis A:General.2010, 388(1-2):102-112
[131]W. Xia, K. Tonosaki, T. Taniike, M. Terano, T. Fujitani, B. P. Liu. Copolymerization of ethylene and cyclopentene with the Phillips CrOx/SiO2 catalyst in the presence of an aluminum alkyl cocatalyst. Journal of Applied Polymer Science.2009, 111(4):1869-1877
[132]W. Xia, B. P. Liu, Y. W. Fang, K. Hasebe, M. Terano. Unique polymerization kinetics obtained from simultaneous interaction of Phillips Cr(VI)Ox/SiO2 catalyst with Al-alkyl cocatalyst and ethylene monomer. Journal of Molecular Catalysis A:Chemical.2006, 256(1-2):301-308
[133]B. P. Liu, P. Sindelar, Y. W. Fang, K. Hasebe, M. Terano. Correlation of oxidation states of surface chromium species with ethylene polymerization activity for Phillips CrOx/SiO2 catalysts modified by Al-alkyl cocatalyst. Journal of Molecular Catalysis A: Chemical.2005,238(1-2):142-150
[134]B. P. Liu, Y. W. Fang, M. Terano. High resolution X-ray photoelectron spectroscopic analysis of transformation of surface chromium species on Phillips CrOx/SiO2 catalysts isothermally calcined at various temperatures. Journal of Molecular Catalysis A: Chemical.2004,219(1):165-173
[135]Y. V. Kissin, L. A. Rishina, E. I. Vizen. Hydrogen effects in propylene polymerization reactions with titanium-based Ziegler-Natta catalysts. Ⅱ. Mechanism of the chain-transfer reaction. Journal of Polymer Science Part A:Polymer Chemistry.2002, 40(11):1899-1911
[136]Y. V. Kissin, L. A. Rishina. Hydrogen effects in propylene polymerization reactions with titanium-based Ziegler-Natta catalysts. I. Chemical mechanism of catalyst activation. Journal of Polymer Science Part A:Polymer Chemistry.2002, 40(9):1353-1365
[137]Y. V. Kissin, R. I. Mink, T. E. Nowlin. Ethylene polymerization reactions with Ziegler-Natta catalysts. I. Ethylene polymerization kinetics and kinetic mechanism. Journal of Polymer Science Part A:Polymer Chemistry.1999,37(23):4255-4272
[138]Y. V. Kissin, A. J. Brandolini. Ethylene polymerization reactions with Ziegler-Natta catalysts. Ⅱ. Ethylene polymerization reactions in the presence of deuterium. Journal of Polymer Science Part A:Polymer Chemistry.1999,37(23):4273-4280
[139]W. Wang, Z. Q. Fan, L. X. Feng, C. H. Li. Substituent effect of bisindenyl zirconene catalyst on ethylene/1-hexene copolymerization and propylene polymerization. European Polymer Journal.2005,41(1):83-89
[140]R. Quijada, A. Narvaez, R. Rojas, F. M. Rabagliati, G. B. Galland, R. S. Mauler, R. Benavente, E. Perez, J. M. Perena, A. Bello. Synthesis and characterization of copolymers of ethylene and 1-octadecene using the rac-Et(Ind)2ZrCl2/MAO catalyst system. Macromolecular Chemistry and Physics.1999,200(6):1306-1310
[141]J. S. Yoon, D. H. Lee, E. S. Park, I. M. Lee, D. K. Park, S. O. Jung. Copolymerization of ethylene/a-olefins over (2-MeInd)2ZrCl2/MAO and (2-BzInd)2ZrCl2/MAO systems. Journal of Applied Polymer Science.2000,75(7):928-937
[142]Y. W. Fang, B. P. Liu, K. Hasebe, M. Terano. Ethylene and 1-hexene copolymerization with CO-prereduced Phillips CrOx/SiO2 catalyst in the presence of Al-alkyl cocatalyst. Journal of Polymer Science Part A:Polymer Chemistry.2005,43(19):4632-4641
[143]K. Weiss, H. L. Krauss. Surface compounds of transition metals,:XXVIII. Polymerization of n-1-alkenes with surface chromium(II) on silica gel support at low temperatures and normal pressure. Journal of Catalysis.1984,88(2):424-430
[144]W. J. Wang, E. Kolodka, S. P. Zhu, A. E. Hamielec, L. K. Kostanski. Temperature rising elution fractionation and characterization of ethylene/octene-1 copolymers synthesized with constrained geometry catalyst. Macromolecular Chemistry and Physics.1999, 200(9):2146-2151
[145]G. B. Galland, R. S. Mauler, L. P. Da Silva, S. Liberman, A. A. Da Silva, R. Quijada. Study of the influence of the reaction parameters on the composition of the metallocene-catalyzed ethylene copolymers using temperature rising elution fractionation and C-13 nuclear magnetic resonance. Journal of Applied Polymer Science.2002,84(1):155-163
[146]Y. D. Fan, Y. H. Xue, W. Nie, X. L. Ji, S. Q. Bo. Characterization of the microstructure of bimodal HDPE resin. Polymer Journal.2009,41(8):622-628
[147]M. Keating, I. H. Lee, C. S. Wong. Thermal fractionation of ethylene polymers in packaging applications. Thermochimica Acta.1996,284(1):47-56
[148]P. Starck, K. Rajanen, B. Logren. Comparative studies of ethylene-α-olefin copolymers by thermal fractionations and temperature-dependent crystallinity measurements. Thermochimica Acta.2003,395(1-2):169-181
[149]F. Chen, R. A. Shanks, G. Amarasinghe. Crystallisation of single-site polyethylene blends investigated by thermal fractionation techniques. Polymer.2001, 42(10):4579-4587
[150]J. Kong, X. D. Fan, Y. C. Xie, W. Q. Qiao. Study on molecular chain heterogeneity of linear low-density polyethylene by cross-fractionation of temperature rising elution fractionation and successive self-nucleation/annealing thermal fractionation. Journal of Applied Polymer Science.2004,94(4):1710-1718
[151]A. J. Miiller, M. L. Arnal. Thermal fractionation of polymers. Progress in Polymer Science.2005,30(5):559-603
[152]D. M. Sarzotti, J. B. P. Soares, L. C. Simon, L. J. D. Britto. Analysis of the chemical composition distribution of ethylene/a-olefin copolymers by solution differential scanning calorimetry:an alternative technique to Crystaf. Polymer.2004, 45(14):4787-4799
[153]K. Czaja, M. Bialek, A. Utrata. Copolymerization of ethylene with 1-hexene over metallocene catalyst supported on complex of magnesium chloride with tetrahydrofuran. Journal of Polymer Science Part A:Polymer Chemistry.2004,42(10):2512-2519
[154]A. Miiller, Z. Hernandez, M. Arnal, J. Sanchez. Successive self-nucleation/annealing (SSA):A novel technique to study molecular segregation during crystallization. Polymer Bulletin.1997,39(4):465-472
[155]C. J. Neves, E. Monteiro, A. C. Habert. Characterization of fractionated LLDPE by DSC, FTIR, and SEC. Journal of Applied Polymer Science.1993,50(5):817-824
[156]S. Hosoda, A. Uemura. Effect of the structural distribution on the mechanical properties of linear low-density polyethylenes. Polymer Journal.1992,24(9):939-949
[157]E. Adisson, M. Ribeiro, A. Deffieux, M. Fontanille. Evaluation of the heterogeneity in linear low-density polyethylene comonomer unit distribution by differential scanning calorimetry characterization of thermally treated samples. Polymer.1992, 33(20):4337-4342
[158]S. Hosoda. Structural distribution of linear low-density polyethylenes. Polymer Journal. 1988,20(5):383-397
[159]H. J. Assumption, J. P. Vermeulen, W. L. Jarrett, L. J. Mathias, A. J. van Reenen. High resolution solution and solid state NMR characterization of ethyl ene/1-butene and ethyl ene/1-hexene copolymers fractionated by preparative temperature rising elution fractionation. Polymer.2006,47(1):67-74
[160]J. T. Xu, L. X. Feng. Application of temperature rising elution fractionation in polyolefins. European Polymer Journal.2000,36(5):867-878