共查询到19条相似文献,搜索用时 156 毫秒
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羊毛—过渡金属络合物的合成及其选择性催化氢化性能的研究 总被引:1,自引:2,他引:1
合成和初步表征了以天然高分子羊毛为载体的羊毛一钯单金属和羊毛-钯-铁双金属络合物催化剂;研究表明,在羊毛-钯络合物催化剂中,引入第二金属能极大地改进它的催化性能,提高其催化选择性,更有效的接近酶催化剂的特征.在常温常压下,以羊毛-钯-铁双金属络合物作催化剂,能顺利地使氯代硝基苯和氯代苯甲醛选择氢化成氯代苯胶和氯代苯甲醇.产率均为100%,有效地抑制了氰取代基的氢解脱除,络合物催化剂中的钯/铁原子比极大地影响着该类氢化反应选择性,在氯代硝基苯和氯代苯甲醛的氢化反应中,最佳的钯/铁原子比分别为1:3和15:1,这时反应的选择性均达到100%,溶剂和温度对氢化反应速度均有一定的影响. 相似文献
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以交联聚席夫碱钯的配合物作为催化剂,对芳香族硝基化合物催化加氢性能进行了研究。该催化剂在常温、常压下可使硝基苯100%催化氢化为苯胺。对某些芳香族硝基化合物转化为相应胺的产率也可达90%以上。此催化剂性能稳定,重复使用80次仍具有一定催化活性。 相似文献
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用聚乙烯呲咯烷酮-钯络合物作为催化剂的硝基化合物的加氢 总被引:1,自引:0,他引:1
制备了以二氧化硅为载体的聚乙烯吡咯烷酮-钯络合物,可在常温常压下催化芳香族硝基化合物的加氢还原反应。其催化活性高于文献值。对硝基苯及间二硝基苯的加氢反应收率可达100%。该体系加入适量乙酸,可显著提高其催化活性,回收使用几乎不降低催化活性,本文还研究了络合物中氮钯克原子比、溶剂及芳香族硝基化合物取代基的种类和位置对加氢速度的影响。 相似文献
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一些高分子金属催化剂能够在常温常压下催化烯烃的加氢反应,具有很高的催化活性和选择性,而且容易回收.这些高分子催化剂所用的载体是以C—C键为主链的有机高聚物.Semikolenov等曾制备过以二氧化硅为载体的有机硅高聚物—金属络合物,即二氧化硅—聚-β-氰乙基硅氧烷—钯络合物作为烯烃的加氢催化剂,但是它的催化活性很低.我们曾经报道过二氧化硅—聚-γ-氰丙基硅氧烷—钯络合物,简写为[SiO_2— 相似文献
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用各种离子交换树脂为载体制备的载钯催化剂可用于对不饱和化合物的常温常压加氢。其加氢活性既与载体功能基的性质有关也与载体的物理特性有关。其中以孔度大、表面粗糙的树脂作载体利于底物与氢的扩散,加氢活性高。载体功能基要求与钯有一定的配位能力,同一功能基的配位原子数最好≤2。催化剂活性中心的价态对加氢活性也有影响,两种以上价态的钯比例适当协同作用时活性高。 相似文献
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用二氧化硅为载体的聚-γ-氰丙基和聚-γ-氨丙基硅氧烷的钯络合物对醛和酮的催化加氢 总被引:2,自引:0,他引:2
<正> 许多过渡金属络合物能够在温和的条件下催化烯烃的均相加氢,但是只有少数络合物能够催化醛酮的均相加氢。 从前我们曾报道过二氧化硅为载体的聚-γ-氰丙基硅氧烷-钯络合物(简称Si-CN-Pd)和聚-γ-氨丙基硅氧烷-钯络合物(Si-NH_2-Pd)能够作为烯烃的加氢催化剂。最 相似文献
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胍乙基-双腈乙基胺乙基及胺乙基-膦酸锆-钯催化剂的催化加氢性能 总被引:7,自引:1,他引:6
由胺乙基膦酸、胍乙基膦酸和N,N双腈乙基胺乙基膦酸制得相应无定形混合磷酸锆载体及其相应的钯催化剂.用IR、TG、DTA和XPS对其进行了表征.研究了影响钯催化剂常压催化加氢活性的各种因素.催化剂对各种取代烯烃和硝基苯有很高的催化加氢活性、选择性和重复使用性.将这类催化剂与钯炭催化剂进行了比较. 相似文献
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利用电纺丝技术制备出苯乙烯-丙烯腈共聚物负载钯的纳米丝催化剂.对催化剂进行了SEM、TEM、IR和XPS的测试.所制备的催化剂对α-己烯催化氢化结果表明,该催化剂在常温、氢气常压下具有很高的催化活性和较好的重复使用性,并且催化氢化过程中存在烯烃的异构化反应.实验结果表明,反应时间为150min时纳米催化剂A对α-己烯催化加氢生成正己烷的转化率是传统催化剂PdCl2/-γAl2O3的4.7倍. 相似文献
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The palladium complex of MgO‐supported melamine‐formaldehyde polymer catalyst was prepared and characterized by X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The preparation of N‐n‐octyl‐D ‐glucamine was investigated by using this complex as the catalyst. It was found that the palladium complex of MgO‐supported melamine‐formaldehyde polymer has a good catalytic activity for the hydrogenation of n‐octylamine with D ‐glucose to produce N‐n‐octyl‐D ‐glucamine. The effects of additive, solvent, temperature, hydrogen pressure, Pd content in the catalyst and the amount of catalyst on the preparation of N‐n‐octyl‐D ‐glucamine have all been studied. Under the optimum experimental conditions—D ‐glucose, 37.2 mmol; n‐octylamine, 31 mmol; triethylamine, 1.0 ml; ethanol, 60 ml; temperature, 333 K; hydrogen pressure, 1.5 MPa; the amount of the catalyst (Pd content 3.55%, N/Pd molar ratio 12), 0.7 g—the highest yield of N‐n‐octyl‐D ‐glucamine (57.6%) was obtained. XRD results show that melamine‐formaldehyde polymer changed the structure of MgO, and XPS results suggest that coordination bonds were formed between the hexatomic ring and metal atom, and palladium particles were immobilized on the polymer. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Chun Fang LI Dong Xiang LI Zhi Jie ZHANG Sheng Yu FENG School of Chemistry Chemical Engineering Shandong University Jinan School of Chemistry Chemical Engineering Materials Shandong Normal University Jinan Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2005,16(10):1389-1392
A great deal of interest has been shown in the field of dendrimer during the past decade1-10.Among the main potential applications of dendrimer,catalysis stands as one of the most promising applications,because dendrimers offer a unique opportunity to combine the advantages of homogeneous and heterogeneous catalysis11.It is possible to change the structure,size,and solubility of dendrimers and metallodendrimers at will12.It has been demonstrated that this metallodendritic catalyst is possible … 相似文献
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Heterogeneous palladium catalysts, a biopolymer complex wool-Pd, have been applied in water-mediated coupling reactions of aryl bromides without assistance of any phosphine ligands. The catalyst was characterized by XPS, ICP. The results showed that aryl bromides could carry out the coupling reaction with a variety of alkenes at 80 °C, in aqueous media under atmospheric condition. More importantly, the cheap catalyst is stable, which shows negligible metal leaching, and retain good activity for at least ten successive runs without any additional activation treatment. This approach would be very useful from a practical viewpoint. 相似文献
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A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with (trimethylsilyl)acetylene catalyzed by MCM-41-supported mercapto palladium(0) complex, followed by desilylation under mild conditions. This polymeric palladium catalyst can be reused many times without any decrease in activity. 相似文献
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《Tetrahedron》2019,75(34):130463
An efficient catalytic system for hydrogenation of ketones and aldehydes using a Cp*Ir complex [Cp*Ir(2,2′-bpyO)(H2O)] bearing a bipyridine-based functional ligand as catalyst has been developed. A wide variety of secondary and primary alcohols were synthesized by the catalyzed hydrogenation of ketones and aldehydes under facile atmospheric-pressure without a base. The catalyst also displays an excellent chemoselectivity towards other carbonyl functionalities and unsaturated motifs. This catalytic system exhibits high activity for hydrogenation of ketones and aldehydes with H2 gas. 相似文献
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Porous polymer supported palladium catalyst for cross coupling reactions with high activity has been successfully prepared by coordination of Pd 2+ species with Schiff bases functionalized porous polymer. The catalyst has been systemically investi-gated by a series of characterizations such as TEM, N 2 adsorption, NMR, IR, XPS, etc. TEM and N 2 isotherms show that the sample maintains the nanoporous structure after the modification and coordination. XPS results show that chemical state of palladium species in the catalyst is mainly +2. More importantly, the catalyst shows very high activities and excellent recycla-bility in a series of coupling reactions including Suzuki, Sonogashira, and Heck reactions. Hot filtration and poison of catalysts experiments have also been performed and the results indicate that soluble active species (mainly Pd(0) species) in-situ gener-ated from the catalyst under the reaction conditions are the active intermediates, which would redeposit to the supporter after the reactions. 相似文献