给电子体控制乙烯聚合反应的动力

研究了给电子体在烯烃聚合催化剂中的作用机理。以体积比为1∶1的γ-氨丙基三甲氧基硅烷和γ-氨丙基三乙氧基硅烷的混合液作为给电子体,在催化剂制备的不同时期加入该给电子体体系对催化剂的性能有很大的影响。加入给电子体大大改善了催化剂催化乙烯聚合动力学行为,易于实现工业化生产。     

丙烯聚合用复合内给电子体催化剂的制备

将自制的内给电子体与芳香二酯内给电子体复配,制备丙烯聚合用新型复合内给电子体催化剂,考察了内给电子体加入温度、用量、负载时间及复配比例等对催化剂性能的影响,并分析了催化剂的表观形态及所制聚丙烯(PP)的性能。确定了催化剂制备的工艺条件:内给电子体与MgCl_2的摩尔比为1∶15,内给电子体的加入温度为80℃,两种内给电子体负载时间均为30min,芳香二酯与磷酸酯的摩尔比为0.5∶0.5。在此条件下制备的催化剂形态良好,所制PP很好地复制了催化剂的形态;PP的等规指数为97.7%,相对分子质量分布为7.1。     

HDC球形催化剂性能优化的研究

利用"正交试验"对HDC催化剂醇合过程中白油/硅油配方进行了优化,同时探讨了在制备过程中加入内给电子体的工艺.结果表明催化剂性能有了明显的提高.     

烯丙基硅烷内给电子体催化剂在丙烯聚合中的应用

以烯丙基硅烷化合物为内给电子体,考察了其与其他不同内给电子体进行复配制备的催化剂的性能,以及对催化剂衰减性能的影响。同时探索了化合物结构中只含硅烷或碳碳双键时对所制备催化剂的影响,以及使用的化合物分子结构中同时含有硅烷及碳碳双键时,制备的催化剂能否起到长效催化剂的作用。结果表明:丙烯聚合用Ziegler-Natta催化剂中内给电子体的结构对丙烯聚合催化剂体系的影响非常大,同一种官能团对于不同种类的内给电子体结构的影响程度不一样;结构中兼具碳碳双键和硅烷的丙烯基硅烷化合物制备的催化剂用于丙烯聚合时的效果不同,其综合性能较好,且具有长期活性,不同结构的烯丙基硅烷化合物对所用的内给电子体具有一定的选择性。     

酮/酯复配内给电子体催化剂的制备及其乙烯聚合评价

用酮类和二酯类为复配内给电子体制备了一种高效乙烯聚合催化剂,用FTIR分析了单个内给电子和复配内给电子体对催化剂结构的影响,结果表明3种催化剂中给电子性能为邻苯二甲酸邻苯二甲酸/二异丁酯乙酰丙酮二异丁酯乙酰丙酮。用凝胶渗透色谱(GPC)和差示扫描量热仪(DSC)对3种催化剂所制备的聚乙烯进行了表征,与单个内给电子体催化剂制备的聚乙烯相比,复配内给电子体催化剂所制备的聚乙烯具有更高的聚合活性,更明显的"共单体效应"和更宽的相对分子量分布。     

外给电子体对丙烯聚合和产品性能的影响

对比分析了气相聚丙烯生产工艺中外给电子体二异丁基二甲氧基硅烷（Donor-B）与四乙基硅烷（Donor-T）对丙烯聚合的影响,并根据工业生产情况研究了不同外给电子体对产品性能的影响。结果表明：在相同的聚合条件下,Donor-B作为外给电子体时,主催化剂活性明显提高,制备的聚丙烯的等规指数较高,刚性和拉伸性能更优;Donor-T作为外给电子体时,催化剂具有更强的氢调敏感性,生产过程稳定可控。     

丙烯聚合用高效球形Ziegler-Natta催化剂制备工艺研究进展

综述了丙烯聚合用高效球形Ziegler-Natta催化剂的两种通用制备方法及其研究进展。采用负载法制备球形催化剂主要包括球形载体的制备和用Ti Cl4处理。乙醇含量不同,球形载体的结构不同,从而会影响催化剂的性能;Ti Cl4的处理温度、处理次数和内给电子体的加入情况等直接影响所制催化剂的性能。采用沉淀析出法制备球形催化剂是通过反应析出法直接得到球形催化剂,所制催化剂的性能主要由催化剂制备工艺决定。催化剂的性能可以通过制备路线和工艺进行有效调控,从而满足不同场合的需求。     

二醚类Ziegler-Natta催化剂催化1-丁烯聚合

采用相同的工艺,制备了含有不同内给电子体[2-甲基-2-丙基-1,3-二甲氧基丙烷、2,2-二异丁基-1,3-二甲氧基丙烷(BIBIMP)、邻苯二甲酸二异丁酯]以及不含内给电子体的MgCl2负载型Ziegler-Natta催化剂,研究了给电子体结构对催化剂活性的影响以及用该催化剂合成的聚1-丁烯(PB)的等规指数、熔点、相对分子质量及其分布。结果表明:未加入外给电子体时,加入BIBIMP的催化剂活性最高,用其所制PB的等规指数最高,分别为539 g/g和84%;加入氢气可进一步提高催化剂活性和PB等规指数;加入外给电子体后,催化剂的活性均降低,二醚类Z-N催化剂活性降低最多,而使用二异丙基二甲氧基硅烷为外给电子体更有助于提高PB的等规指数。     

内给电子体在气相聚乙烯催化剂中作用的研究

采用浸渍法制备工艺,在MgCl2/SiO2复合载体齐格勒-纳塔(Z-N)催化剂制备过程中加入了醇、酯、醚和硅烷四类内给电子体,考察了不同内给电子体对气相聚乙烯催化剂的活性、产物堆密度、细粉含量的影响;结果表明:正硅酸乙酯作为聚乙烯催化剂的内给电子体效果较好,催化剂活性达到3447.5g·PE/g·Cat·h,聚合物堆密度达到0.33g·cm-3,细粉含量仅占0.052%,电子显微镜下催化剂颗粒呈均匀的球形。     

琥珀酸酯对映异构体的合成及其用于丙烯聚合催化剂

合成了具有不同旋光性的2,3-二异丙基琥珀酸二乙酯(DISE)对映异构体并作为内给电子体用于丙烯聚合催化剂。本工作发现,只有使用D-薄荷醇制备的R,R构型的(+)-2,3-二异丙基琥珀酸二-D-薄荷醇酯才能够通过结晶分离得到纯品,这也是进一步制备相应的(+)-2,3-二异丙基琥珀酸二乙酯的关键所在。本工作还研究了不同旋光性的2,3-二异丙基琥珀酸二乙酯作为内给电子体对丙烯聚合催化剂性能的影响。实验结果表明,尽管两种对映异构体分子构型不同,但其作为内给电子体的性能没有显著的差别,并且都能够赋予催化剂很好的聚合性能。     

一种新型丙烯聚合催化剂的研究

阐述在一定的条件下制备了一种新型的用于丙烯聚合的负载型Ziegler/Natta催化剂,在此催化剂体系中添加了一种新的内给电子体BN,结果表明:此种催化剂具有催化活性高,粒度非常集中,聚合得到的聚丙烯细粉少,此催化剂氢调敏感,等规度可调,聚合物性能好等特点.     

丙烯聚合用BCZ型催化剂的开发

在MgCl2溶解过程中加入内给电子体,开发了一种新型丙烯聚合用BCZ型催化剂,并在5 L聚合釜中进行了本体聚合考核评价,在12 m3小本体工艺装置上进行工业应用试验,在25 kg/h的连续法Innovene气相工艺装置进行中试试验。研究表明:用BCZ型催化剂制备聚丙烯(PP)时,催化剂活性高出国产同类催化剂近50%,氢调敏感性好,同样氢气用量下,PP的熔体流动速率可提高25%左右;所制PP的相对分子质量分布大于7.5,等规指数高;BCZ型催化剂可用于小本体法工艺、连续法气相工艺装置制备均聚和共聚PP。     

Effects of external electron donor on catalyst active sites in propylene polymerization

In order to investigate the effects of an external electron donor on catalyst active sites in propylene polymerization, physical properties of the produced polymers are measured with various techniques. From the thermal analysis and gel permeation chromatography (GPC) measurement, it is found that an external electron donor transfers the catalyst active sites from atactic sites via low isospecific sites to high isospecific sites. There are some differences between gas and slurry phase reactions. This may be due to the differences in diffusion phenomena with polymerization types. Polymer crystalline formations, such as spherulite and lamella structure, are observed by an image analyzer and closely coincide with the GPC results in molecular weight of polypropylene. From the results of ultraviolet visible (UV VIS) and Fourier transform infrared (FTIR) experiments, it is found that some complexes are formed between cocatalyst and the external electron donor, and it is supposed that those complexes are strongly associated with catalyst active site transition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1779–1787, 1998     

大港石化聚丙烯装置的助剂及催化剂试用试验

介绍了三乙基铝、给电子体、白油及凡士林脂等助剂及DJD—B催化剂在大港石化10万吨／年聚丙烯生产装置上的试用试验。各种助剂都可生产符合企业标准要求的聚丙烯产品,白油及凡士林脂的试用过程中催化剂输送管线压力波动,对生产的平稳性有一定影响。DJD—B催化剂活性较高,氢调敏感性好,产品质量合格。     

Effect of phenyltriethoxysilane as external donor on the microstructure of ethylene-propylene copolymers

Summary The effect of an external electron donor, namely, phenyltriethoxysilane (PES) on the compositional heterogeneity and the microstructure of ethylene-propylene copolymers prepared using a titanium-magnesium catalyst has been investigated. Addition of PES causes an increase in the average sequence length of ethylene and propylene. The products of reactivity ratios of ethylene and propylene indicate that the copolymer is blocky in nature. The external donor produces a propylene sequence in the copolymer which is richer in mmmm pentads.NCL Communication No. 5696     

Ziegler-Natta型丙烯聚合催化剂内给电子体复配的研究进展

简述了Ziegler-Natta催化剂内给电子体的作用,指出通过内给电子体复配可以使其优势互补,得到综合性能更优的催化剂。深入调研了国内外相关单位的研究动向,以LyondellBasell公司、DOW公司、中国石油化工股份有限公司北京化工研究院等多个研究单位为着眼点,阐述了复配内给电子体的研究进展,展望了内给电子体复配的广阔前景。     

Influence of cocatalyst on the structure and properties of polypropylene/poly (ethylene‐co‐propylene) in‐reactor alloys prepared by MgCl2/TiCl4/diester type Ziegler‐Natta catalyst

In this work, a series of polypropylene/poly(ethylene‐co‐propylene) (iPP/EPR) in‐reactor alloys were prepared by MgCl₂/TiCl₄/diester type Ziegler‐Natta catalyst with triethylaluminium/triisobutylaluminium (TEA/TIBA) mixture as cocatalyst. The influence of cocatalyst and external electron donor, e.g., diphenyldimethoxysilane (DDS) or dicyclopentyldimethoxysilane (D ‐donor), on the structure and mechanical properties of iPP/EPR in‐reactor alloys were studied and discussed. According to the characterization results, PP/EPR was mainly composed of random poly(ethylene‐co‐propylene), segmented poly(ethylene‐co‐propylene), and high isotactic PP. Using TEA/TIBA mixture as cocatalyst and DDS as external electron donor, as TEA/TIBA ratio increased, the impact strength of iPP/EPR in‐reactor alloys had an increasing trend. Using TEA/TIBA mixture as cocatalyst and D ‐donor as external electron donor, the impact strength of iPP/EPR in‐reactor alloy were dramatically improved. In this case, the iPP/EPR in‐reactor alloy prepared at TEA: TIBA = 4 : 1 was the toughest. The influence of cocatalyst and external electron donor on the flexural modulus and flexural strength could be ignored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies on the effects of external electron donor in propylene polymerization

In order to investigate effects of an electron donor in propylene polymerization (in gas and slurry phase reactions each) by using a 3rd generation Ziegler-Natta catalyst, the catalytic activities were measured before and after the addition of an electron donor. And physical properties of produced polymer were estimated. Polymerization rate was decreased with increasing EB/A1 mole ratio because atactic sites on catalyst were selectively poisoned by the addition of the electron donor, and consequently total number of active sites were diminished. It was found that the overall reaction order was the 2nd order, and a reaction rate form was suggested by using a CO inhibition technique. Catalyst deactivation was due to the formation of dense isotactic polypropylene on the catalyst at the beginning of polymerization so that monomers had the difficulties in diffusion into catalyst surface through the dense polymer. From the measurements of polymer physical properties, probability of active site transitions from atactic→low isotactic→high isotactic sites could be considered, which may be due to the formation of a complex between co-catalyst and electron donor.     

Electrocatalytic activity of Pt/C catalysts for methanol electrooxidation promoted by molybdovanadophosphoric acid

A Pt/C catalyst modified by the Keggin-structure molybdovanadophosphoric acid (PMV) is prepared by cyclic voltammetry and the modified Pt/C catalyst is studied for methanol electrooxidation. The results show that the PMV modified Pt/C catalyst has increased the electron transfer coefficient of the rate-determining step and diminished the adsorption of CO on Pt/C catalysts. Significant improvements in the catalytic activity and stability for methanol electrooxidation are observed, and it indicates that the PMV combined with Pt/C catalyst can be considered as a good electrocatalyst material for potential application in direct methanol fuel cells.