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综述了烯烃聚合钯催化剂的研究进展,烯烃聚合钯催化剂的配体类型有膦配体、氮配体、碳配体、氧配体、氮-氧配体、膦-氧配体、氮-膦配体等。与齐格勒-纳塔催化剂和茂金属催化剂相比,烯烃聚合钯催化剂具有高催化活性、单活性中心和良好的分子剪裁性等优点,可在分子层次上实现烯烃聚合的分子设计与组装;与铁、钴、镍等后过渡金属催化剂相比,烯烃聚合钯催化剂具有反应条件较温和、催化活性和立体选择性较高的优势。 相似文献
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过渡金属氧化物(TMOs)是阴离子交换膜燃料电池最有前途的氧还原催化剂之一. 目前,TMOs的氧还原活性同铂基催化剂相比仍然有一定的差距,研究如何合成具有高催化活性的TMOs催化剂非常重要. 导电性和本征活性一直被认为是开发高性能TMOs催化剂的两个关键因素,本文着重总结与评述了近年来有关TMOs氧还原催化剂在导电性和本征活性方面的研究进展,尝试提出了未来提高TMOs氧还原催化活性的努力方向. 相似文献
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Werner J. Blank 《Macromolecular Symposia》2002,187(1):261-270
Environmental, safety and health concerns are major driving forces for the development of new coating systems, which in turn require catalysts with a different performance profile. One critical area for the development of new catalysts is the replacement of organotin compounds in polyurethanes with environmentally friendly catalysts, such as bismuth, aluminum and zirconium chelates. For applications in epoxies new catalysts for the epoxy-carboxyl reaction are also being developed. To gain the needed improved performance multiple cure mechanisms are being employed in coatings requiring dual action catalysts. 相似文献
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随着聚合用稀土催化剂本质的深入研究,不断出现新的催化剂和聚合物,其中一些催化剂已实现工业比生产.本文以稀土催化剂在烯烃、双烯烃和其它单体的聚合物领域中较为突出的主要成就为中心,扼要地介绍稀土催化剂在高分子科学和工业上的最新进展. 相似文献
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With the enhancement of the people consciousness of environment protection, soot particulates(PM)elimination has drawn wide attention in recent years. Efficient after-treatment with well-designed catalysts is one of the best ways to eliminate soot particulates that come from diesel engines. Catalysts coated on the DPF(diesel particulate filter) are considered as the main factor to lower soot ignition temperature.Improvement of the structures of the catalysts is significantly important in order t... 相似文献
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A new range of polar imidazolium and phosphate-containing ligands was synthesised from readily available starting materials in high yielding multi-step transformations. These ligands were used to generate Pd catalysts for Suzuki and Heck C–C coupling reactions in organic and organic/aqueous media. The catalysts performed well in aqueous media in the Suzuki reaction and less well in the Heck reaction, related to substrate solubility in the aqueous media. When moving to ionic liquids, the Heck reaction dramatically improved, especially in media compatible with the polar catalysts and the non-polar reagents. In all cases, the catalysts were stable to the formation of Pd black, a form of degradation that frequently befalls Pd catalysts. The catalysts could be successfully recycled without loss of activity. 相似文献
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The Grubbs' first and second generation catalysts were occluded into cross-linked slabs of polydimethylsiloxane with volumes from 1 mm3 to 1 cm3 by swelling the polymer with catalyst and methylene chloride. Methylene chloride was evaporated under vacuum to yield occluded catalysts where their solvent was polydimethylsiloxane. These occluded catalysts were reacted with alkenes dissolved in H2O or H2O/MeOH mixtures that diffused into the polydimethylsiloxane to react by ring-closing metathesis and cross metathesis. Control experiments revealed that the catalysts remained occluded and metathesis did not occur in the solvent. Occlusion of these catalysts allowed commercially available Grubbs' catalysts to be used with H2O as the solvent while isolating the H2O sensitive ruthenium methylidene from exposure to H2O. Functional group selective experiments were carried out where the polydimethylsiloxane was an "active" membrane to exclude salts. Polydimethylsiloxane is a hydrophobic polymer, so the deprotonated salt of diallylmalonic acid did not diffuse into it while a diallylether diffused into it and reacted by metathesis. Thus, by controlling the polarity of reagents their reactivity can be controlled owing to the properties of polydimethylsiloxane rather than those of the Grubbs' catalysts. Occlusion of catalysts in polydimethylsiloxane has been shown to add new selectivities to mature catalysts. 相似文献
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多相不对称催化氢化研究进展* 总被引:7,自引:0,他引:7
本文综述了多相不对称催化氢化反应的最新研究进展.特别是对最近几年来两个典型的多相不对称催化氢化体系即酒石酸盐修饰镍催化剂催化β-酮酸酯的不对称氢化反应体系和金鸡纳生物碱修饰铂催化剂催化α-酮酸酯的不对称氢化反应体系进行了详细的介绍和讨论,同时展望了多相不对称催化氢化反应研究的前景. 相似文献
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目前单原子催化剂的研究呈现爆发式增长, 已然成为材料科学和催化领域的明星材料和研究热点. 前期报道的单原子催化剂研究主要针对某一个应用方向进行探讨, 较少研究催化剂的双功能或多功能应用. 近年来, 为了拓展单原子催化剂在更多领域和方向的应用, 具有双功能甚至多功能的单原子催化剂的设计开发备受关注. 本文综合评述了近年来具有双功能活性的单原子催化剂的研究进展, 重点介绍了其在电化学领域中的最新应用研究. 最后, 对具有双功能活性的单原子催化剂发展研究中存在的问题进行了简要分析, 并对未来发展前景进行了展望. 相似文献
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