共查询到20条相似文献,搜索用时 153 毫秒
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Unipol工艺聚乙烯Ziegler-Natta催化剂研究及应用进展 总被引:1,自引:0,他引:1
综述了8种适用于Unipol工艺气相聚乙烯Ziegler-Natta催化剂的制备路线,分析了各催化剂的优缺点:M催化剂应用范围广,但活性低;BCG-Ⅳ催化剂制备中加入促进剂,初始活性和总活性都高;SCG-1催化剂制备工艺简单,活性适中;GM催化剂在载体活化过程中引入了特殊结构的给电子体,催化剂活性高、聚合物堆积密度也高;J催化剂性能优异,是Unipol工艺催化剂的发展方向;BCS-02催化剂较适合冷凝态操作;BCS-01催化剂制备工艺独特,但制备条件要求高;SLC-S催化剂不以硅胶作为载体,在保证催化剂高效率的同时,成本大大降低。对我国Unipol工艺Ziegler-Natta催化剂的研究及国产化提出了建议。 相似文献
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以偕胺肟纤维(AOCF)为载体与AgNO3通过配位反应,再经水合肼还原制备纳米银/偕胺肟纤维(Ag/AOCF)。用扫描电镜观察纤维表面形貌。以Ag/AOCF为光催化剂,活性黄为降解对象,研究了Ag/AOCF的制备工艺和光催化降解反应的条件对降解率的影响,并考察了催化剂的重复使用与再生。结果表明,在硝酸银浓度为0.010 mol/L、配位反应时间为40 min、pH=3.0条件下制备的催化剂对活性黄的光催化降解效率最佳;当活性黄溶液的pH=3.0、太阳光光源、催化剂用量为0.25 g/L时催化降解活性黄,降解效率能达到95.7%,且催化剂在重复使用了4次后,其对活性黄的光催化降解效率仍能保持在80%以上。用四氢呋喃再生后可重复使用。 相似文献
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《化纤文摘》1999,(1)
991323烯烃聚合的新催化剂Freemantle M.;Chemieal Engineering News,1998,76,(15),p .11一12(英)美国和英国的研究小组发现了以铁和钻为基础的新的催化剂家族,这种催化剂对乙烯聚合有高的活性。这种络合物当用共催化剂甲基铝环氧乙烷(MAO)活化后产生高密度聚乙烯。络合物含芳亚胺配位体,制造简单。两个小组制备了5种由三配位基铁(I)和钻(厄)与2,6一双胺毗陡配位体组成的原络合物,而2,6一双胺p比陡配位体通过两个等价的烷基取代胺与2,6一双乙酞毗淀经缩聚而成。乙烯聚合试验表明格外高的MAO催化活性。(张桂水)烯烃粱合催化剂活性 99132… 相似文献
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Hui Mao Xuepin Liao Wenhua Zhang Bi shi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(8):1104-1110
BACKGROUND: Synthetic ligands have conventionally been used for the preparation of homogenous Rh complex catalyst but biomass has rarely been utilized for this purpose. In the present investigation, plant tannins (natural polyphenols) were used as water‐soluble ligands for the preparation of homogenous Rh3+ complex catalysts. RESULTS: Based on X‐ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance (HNMR) analyses, the preparation mechanism of these complex catalysts was proven to involve chelating interactions between Rh3+ and the adjacent phenolic hydroxyls of plant tannins. As a result, the use of plant tannin promoted aqueous‐organic biphasic interactions and the plant tannin‐chelated Rh3+ complex catalysts exhibited much higher catalytic activity than commercial Rh complex catalysts in the biphasic hydrogenation of quinoline. Furthermore, the plant tannin‐chelated Rh3+ complex can be reused three times without significant loss of catalytic activity CONCLUSION: Our experimental results suggested that black wattle tannin (BWT) can be used as water‐soluble ligands for the preparation of highly active and recyclable Rh3+ complex catalysts. Copyright © 2012 Society of Chemical Industry 相似文献
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Several parameters involved in preparing the complex metal-oxide (CMO) catalysts (MaVbTecNbdOn, M: Mo and W) for the selective oxidation of propane to acrylic acid (AA) were investigated and discussed. These include the role each metal element plays and the effects on the performance of the catalysts exerted by the proper metal ratio, as well as various preparation methods, such as the mixing of starting chemicals to form an aqueous precursor mixture, the solvent removal, and the proper calcination atmosphere and gas flow. It was found that each metal element plays a critical role and while an appropriate MoVTeNb metal ratio is critical to the formation of an effective catalyst, each and every step of the preparation methods also have profound effects on the structures and performance of the resulting catalysts. The preferred preparation method for an effective MoVTeNb oxide catalyst includes the intimate mixing of all starting chemicals to form a precursor solution, drying via rotavap for solvent removal followed by calcination under a non-flow inert atmosphere. Using this preferred preparation method, effective complex metal-oxide catalysts can be prepared which affords up to 73% propane conversion and 42% one-pass yield to acrylic acid, while undesirable preparation methods, in contrast, lead to very ineffective catalysts of the identical composition. 相似文献
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固体超强酸催化剂改性研究进展 总被引:67,自引:0,他引:67
负载型固体超强酸是近年来发展的一种新型催化材料 ,对许多化学反应有较好的催化活性、选择性及重复使用性能 ,并可催化许多均相反应难以进行的各种化学反应。综述了国内外此类催化剂改性研究的最新进展 ,包括载体、促进剂、制备条件、酸中心结构的研究、利用纳米技术制备固体超强酸催化剂。讨论了固体超强酸催化剂理论及催化剂现代表征方法 ,催化剂酸中心形成、失活机理 ,固体超强酸催化剂的应用。最后指出了今后固体超强酸催化剂的发展方向 相似文献
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采用溶剂热法合成了以三核碘化亚铜(CuI)四面体结构为活性中心的硅氢加成反应催化剂,探讨了物料比对产物收率的影响。结果说明了当配体与碘化亚铜的摩尔比为1:6时,产物收率最高。通过元素分析、傅里叶红外光谱分析、X射线光电子能谱分析、X射线单晶体衍射分析、紫外可见光光谱分析、热失重分析对配合物的化学组成、空间结构及性能进行表征,并进一步通过甲基苯基乙烯基树脂和甲基苯基含氢硅油的硅氢加成反应进行催化固化效果验证。结果说明了在催化剂填加量为0.04%、固化温度为150℃的优化条件下反应24h,共混体系固化效果最佳。该配合物对硅氢加成反应具有很好的催化性能,并且原料成本低、制备方法简单、晶体颗粒方便储存,有望解决硅氢加成反应中贵金属催化剂的高成本问题。 相似文献
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The anion exchange resin Amberlyst, A-26, forms an efficient matrix for the immobilization of the water soluble complex, HRh(CO)(m-C6H4SO3Na)3)3. Catalysis proceeds in anhydrous alcohol solvents which allows the conversion of water insoluble olefins to aldehydes. Activities and selectivities are similar to both supported aqueous phase catalysts and to the neutral complex, HRh(CO)(PPh3)3 in non-aqueous solvents. The catalyst preparation minimizes the quantity of water in the supported catalyst; the lack of water is thought to be responsible for an increase in catalyst stability toward oxidation. 相似文献
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Mn(Salen)/Al-HMS催化剂微波固相法制备及其催化性能 总被引:2,自引:0,他引:2
采用新的微波固相法制备出Mn(Salen)/Al-HMS催化剂。通过FT IR和TG的表征,结果表明,微波固相方法成功地将Mn(Salen)配合物固载于介孔Al-HMS分子筛中。以苯乙烯环氧化反应为例比较了不同方法制备的催化剂的催化性能,发现微波固相法制备的Mn(Salen)/Al-HMS-IP催化剂具有较高的催化活性和最好的环氧化物选择性,此外,考察了催化剂性能还与制备过程中的微波辐射时间、反应时间、反应溶剂、反应温度、氧化剂的用量及催化剂的重复使用对微波固相法制备的催化剂的性能影响规律,得到了满意的结果。 相似文献