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1.
以2-(二苯基膦)乙基三乙氧基硅烷和正硅酸乙酯为混合硅源, 采用延时共缩聚法经表面活性剂F127自组装合成了二苯基膦(PPh2)修饰的SBA-16纳米介孔分子筛(PPh2-SBA-16), 通过PPh2配体络合Ru(Ⅱ)化合物制备出固载化的Ru(Ⅱ)非均相催化剂(Ru-PPh2-SBA-16), 样品仍然保持了SBA-16的规整孔道结构. 以水相中高烯丙醇异构化反应为探针, 考察了所制备催化剂的催化性能, 发现其对目标产物具有高选择性, 虽然其催化活性略低于对应的均相Ru(Ⅱ)催化剂, 但该催化剂易与产物分离, 且重复使用三次后催化效率基本不变, 活性相与载体结合牢固, 不存在明显的脱落和流失, 因此更适合于工业化应用.  相似文献   

2.
采用正硅酸乙酯和有机金属Ru(II)硅烷在模板剂P123作用下共聚,合成出有序介孔Ru(II)有机金属催化剂,通过FTIR、NMR、XRD、TEM、N2吸附脱附等对催化剂进行了系统表征;将该催化剂应用于水介质中烯丙醇型异构化反应,结果表明,其具有高活性和高选择性,催化效率接近均相催化剂,且能够多次重复使用,有望在绿色化工中推广应用.  相似文献   

3.
以1,4-双(三乙氧基硅基)苯和2-(二苯基膦)乙基三乙氧基硅烷为混合硅源, 在表面活性剂作用下共缩聚得到二苯基膦功能化的有序介孔有机硅材料[PPh2-PMO(Ph)], 通过配位作用将Rh(Ⅰ)有机金属催化剂固载到PPh2-PMO上得到Rh(Ⅰ)-PPh2-PMO(Ph)非均相催化剂, 并采用FTIR, NMR, XRD, TEM和氮气吸附等手段对催化剂进行了表征. 考察了该催化剂在水介质Heck反应中的催化性能, 实验结果表明, 所制备的Rh(Ⅰ)-PPh2-PMO(Ph)具有与均相催化剂Rh(PPh3)3Cl相当的催化活性, 这主要归因于催化剂的高比表面积、有序介孔结构有利于提高Rh(Ⅰ)活性位的分散度, 减少了传质阻力; 同时PMO构建形成的微环境增强了表面疏水性, 有利于反应底物的吸附和扩散. 此外, 催化剂重复使用多次后活性仍没有明显降低.  相似文献   

4.
手性多孔有机聚合物具有较高的稳定性和催化活性,广泛用于多相不对称催化中.目前研究多集中在合成具有微孔结构的聚合物,而少有具有多种孔道结构(包含介孔和微孔)的聚合物的报道.之前我们报道了乙烯基修饰的BINAP配体,(S)-5,5’-divinyl-BINAP,将其与不同单体共聚后得到了一系列具有不同孔结构的有机聚合物.其负载的Rh基催化剂在苯乙烯不对称氢甲酰化反应中,表现出比均相更高的产物对映体选择性.本文采用不同的溴代步骤,合成了(S)-4,4’-divinyl-BINAP配体.将这两种具有乙烯基官能团的手性配体按相同的摩尔比与二乙烯基苯(DVB)共聚,得到两种不同的有机聚合物.负载[RuCl_2(benzene)]_2后,分别得到Ru/4-BINAP@POPs和Ru/5-BINAP@POPs-1.采用一锅法合成了催化剂Ru/5-BINAP@POPs-2;以[RuCl_2(p-cyme)]_2和RuCl_3分别合成了Ru/5-BINAP@POPs-3和Ru/5-BINAP@POPs-4催化剂.N2物理吸附结果显示,Ru/4-BINAP@POPs和Ru/5-BINAP@POPs-1催化剂具有相似的孔道结构;而采用一锅法合成的Ru/5-BINAP@POPs-2催化剂的介孔孔径较大.4-BINAP@POPs和5-BINAP@POPs聚合物的~(13)C核磁显示,其均在145,137和128 ppm处有明显的吸收峰,可归结为萘环和苯环上的碳振动峰;在44.0 ppm处的峰归属为亚甲基上的碳振动峰;31P核磁显示,在聚合物中P基本没有被氧化.将所得到的Ru/POPs催化剂应用于乙酰乙酸甲酯的多相不对称加氢反应中,Ru/5-BINAP@POPs-1催化剂具有与Ru/4-BINAP@POPs更快的反应速率.在相同反应条件下,催化剂活性大小为Ru/5-BINAP@POPs-1Ru/5-BINAP@POPs-3Ru/5-BINAP@POPs-4Ru/5-BINAP@POPs-2.另外Ru/5-BINAP@POPs-1催化剂对β-酮酸酯有着较好的底物适应性,且在釜式反应中可循环使用6次而活性基本不变.分析发现,使用前后的催化剂均没有明显的Ru–Ru键的存在.表明Ru金属高度分散于催化剂上,且具有较高的稳定性,金属不易聚集,这也是其具有高活性和稳定性的原因.  相似文献   

5.
不对称加氢催化剂[Ru(BINAP)(OAc)2]的合成及其固载化研究   总被引:1,自引:0,他引:1  
对文献报道的实验反应条件进行优化改进后,合成了不对称加氢催化剂[Ru((S)-BINAP)(OAc)2]和[Ru((R)-BINAP)(OAc)2]。将合成的催化剂应用于惕各酸的不对称催化氢化,(S)-2-甲基丁酸得率为88%,立体选择性可达85%e.e.。为了提高催化剂的利用率,将催化剂[Ru(BINAP)(OAc)2]负载在新型介孔分子筛SBA-15上,用于惕各酸的不对称催化氢化,循环应用3次后,(S)-2-甲基丁酸得率仍可达到59%,立体选择性达57%e.e.。  相似文献   

6.
手性多孔有机聚合物具有较高的稳定性和催化活性,广泛用于多相不对称催化中.目前研究多集中在合成具有微孔结构的聚合物,而少有具有多种孔道结构(包含介孔和微孔)的聚合物的报道.之前我们报道了乙烯基修饰的BINAP配体,(S)-5,5'-divinyl-BINAP,将其与不同单体共聚后得到了一系列具有不同孔结构的有机聚合物.其负载的Rh基催化剂在苯乙烯不对称氢甲酰化反应中,表现出比均相更高的产物对映体选择性.本文采用不同的溴代步骤,合成了(S)-4,4'-divinyl-BINAP配体.将这两种具有乙烯基官能团的手性配体按相同的摩尔比与二乙烯基苯(DVB)共聚,得到两种不同的有机聚合物.负载[RuCl2(benzene)]2后,分别得到Ru/4-BINAP@POPs和Ru/5-BINAP@POPs-1.采用一锅法合成了催化剂Ru/5-BINAP@POPs-2;以[RuCl2(p-cyme)]2和RuCl3分别合成了Ru/5-BINAP@POPs-3和Ru/5-BINAP@POPs-4催化剂.N2物理吸附结果显示,Ru/4-BINAP@POPs和Ru/5-BINAP@POPs-1催化剂具有相似的孔道结构;而采用一锅法合成的Ru/5-BINAP@POPs-2催化剂的介孔孔径较大.4-BINAP@POPs和5-BINAP@POPs聚合物的13C核磁显示,其均在145,137和128 ppm处有明显的吸收峰,可归结为萘环和苯环上的碳振动峰;在44.0 ppm处的峰归属为亚甲基上的碳振动峰;31P核磁显示,在聚合物中P基本没有被氧化.将所得到的Ru/POPs催化剂应用于乙酰乙酸甲酯的多相不对称加氢反应中,Ru/5-BINAP@POPs-1催化剂具有与Ru/4-BINAP@POPs更快的反应速率.在相同反应条件下,催化剂活性大小为Ru/5-BINAP@POPs-1>Ru/5-BINAP@POPs-3>Ru/5-BINAP@POPs-4>Ru/5-BINAP@POPs-2.另外Ru/5-BINAP@POPs-1催化剂对β-酮酸酯有着较好的底物适应性,且在釜式反应中可循环使用6次而活性基本不变.分析发现,使用前后的催化剂均没有明显的Ru–Ru键的存在.表明Ru金属高度分散于催化剂上,且具有较高的稳定性,金属不易聚集,这也是其具有高活性和稳定性的原因.  相似文献   

7.
TiO2-CeO2介孔复合氧化物的合成及应用   总被引:9,自引:0,他引:9  
以氯化十六烷基吡啶(C16PyCl)为模板剂, 在室温、中性条件下合成了TiO2-CeO2介孔复合氧化物, 分别用红外光谱(FT-IR)、X射线粉末衍射(XRD)和BET 比表面测定等技术对介孔TiO2的结构、晶相和比表面积进行了表征. 结果表明, Ce4+的引入能稳定介孔结构. 负载活性组分Ru 后, Ru 颗粒与介孔复合载体发生相互作用, 尽管可能会部分堵塞孔道, 但对于甲醇分解为CO 和H2, Ru/m-TiO2-CeO2的催化活性依然远高于Ru/m-TiO2. Ru 和CeO2之间的相互作用对甲醇分解反应表现出协同效应.  相似文献   

8.
介孔炭的孔结构对其负载的Ru基氨合成催化剂性能的影响   总被引:1,自引:0,他引:1  
采用模板法合成了介孔炭(MC),研究了其孔结构对其负载的Ru基氨合成催化剂Ba-Ru-K/MC性能的影响,采用N2吸附脱附、扫描电镜和透射电镜等手段对介孔炭的孔结构进行了表征.研究发现,介孔炭载体的孔结构取决于模板剂的用量,当SiO2/C质量比为1.0时,所制介孔炭比表面积最大.介孔炭负载的Ba-Ru-K催化剂活性与其介孔比表面积相关.在425℃,10MPa和10000h-1条件下,合成氨的反应速率为139mmol/(gcat·h).  相似文献   

9.
共轭羰基化合物的羰基选择性加氢反应被广泛用于制备重要的药物和化学中间体.利用氮掺杂碳纳米笼(hNCNC)大的比表面积和掺杂氮原子的锚定作用,构建了10 wt% Ru负载量的Ru/hNCNC催化剂,尺寸约2.4 nm的Ru纳米颗粒高度均匀地分散在hNCNC表面.用于催化苯乙酮选择性加氢制1-苯乙醇,在50.0℃、2.0 MPa H2的温和条件下,展现出优异的催化加氢性能:反应2.0 h后的苯乙酮转化率和1-苯乙醇选择性分别达到96.2%和95.8%,远优于未掺杂碳纳米笼(hCNC)和活性炭负载的Ru催化剂;循环使用6次后,其苯乙酮转化率仅略有下降(从96.2%到94.0%),明显优于Ru/hCNC.Ru/hNCNC的优异催化性能可归因于:hNCNC大的比表面积和掺杂氮原子的锚定作用有利于Ru纳米粒子的分散和固载、独特的微孔-介孔-大孔共存的分级孔结构有利于传质、掺杂氮原子有效调变了Ru催化剂的电子结构.  相似文献   

10.
以在室温条件下快速制备的一系列Ru掺杂的MCM-48介孔分子筛为催化剂,进行了无溶剂条件下空气催化氧化环己烷制环己醇和环己酮的反应研究,并通过XRD、N2吸附脱附、FT-IR等多种表征手段对该催化剂进行系统研究.表征结果表明该催化剂具有典型的MCM-48介孔材料结构,合成过程中加入的Ru以不同形态同时存在于催化剂中.催化反应的结果显示该催化剂在较温和反应条件下具有良好催化活性,并且不同的Ru物种在反应中呈现不同的活性.  相似文献   

11.
PPh(2)-functionalized SBA-15 was synthesized by co-condensation of tetraethyl orthosilicate and 2-(diphenylphosphino)ethyltriethoxysilane through prehydrolysis. The as-prepared PPh(2)-SBA-15 was used as the support to immobilize the Ru(II) organometallic catalyst through the strong coordination between the Ru(II) and the PPh(2)-ligand (Ru-PPh(2)-SBA-15). During 1-phenyl-3-buten-1-ol isomerization carried out in water as an environmentally friendly medium, the Ru-PPh(2)-SBA-15 catalyst exhibited almost the same activity and selectivity as the corresponding RuCl(2)(PPh(3))(3) homogeneous catalyst and could be used repetitively nearly 7 times. On the basis of various characterizations, the correlation of the catalytic behaviors of the Ru-PPh(2)-SBA-15 to its structural characteristics was discussed briefly. Obviously, the high activity of the Ru-PPh(2)-SBA-15 could be attributed to both the high surface area of the support, which ensured the good dispersion of Ru(II) active sites, and the ordered mesoporous structure, which facilitated the diffusion of organic reactants.  相似文献   

12.
Here we demonstrate for the first time the encapsulation of a chiral oxazaborolidine complex in the 3D mesoporous channels of an amine functionalized KIT-6 material via covalent bonding through a post-synthetic approach. The physico-chemical properties of the pure and immobilized KIT-6 catalysts were obtained by various techniques such as XRD, nitrogen adsorption, HRSEM, UV-Vis diffuse reflectance spectroscopy, and FT-IR spectroscopy. It has been found that the structural stability of the KIT-6 was not affected even after the immobilization of a significant amount of chiral ligand inside the mesoporous channels of the support. However, the values of structural parameters such as the specific surface area and the specific pore volume of the KIT-6 support was significantly lower than the pure KIT-6 support. The chemical interaction between the chiral ligand inside the mesochannels and the KIT-6 support was also confirmed by UV-Vis and FT-IR spectroscopy. The chiral catalytic performance of the immobilized catalysts for the enantioselective reduction of aromatic prochiral ketones was demonstrated and the results were compared with chiral catalyst immobilized supports with uni-dimensional porous structures, such as MCM-41 and SBA-15. Among the catalysts studied, chiral catalyst immobilized KIT-6 showed the highest performance with a high product yield and a high enantioselectivity due to its 3D porous structure with two continuous and interpenetrating systems of chiral channels and an interwoven 3D cylindrical type pores of Ia3d symmetry. The catalyst also exhibited much better recycling capability than other chiral catalyst supported mesoporous materials used in the study.  相似文献   

13.
Controlled-potential electrochemical oxidation of cis-[Ru(ROCS2)2(PPh3)2] (R = Et, iPr) yielded corresponding Ru(III) complexes, and the crystal structures of cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2](PF6) were determined. Both pairs of complexes exhibited almost identical coordination structures. The Ru-P distances in trans-[Ru(III)(ROCS2)2(PPh3)2](PF6) [2.436(3)-2.443(3) A] were significantly longer than those in cis-[Ru(II)(ROCS2)2(PPh3)2] [2.306(1)-2.315(2) A]: the smaller ionic radius of Ru(III) than that of Ru(II) stabilizes the trans conformation for the Ru(III) complex due to the steric requirement of bulky phosphine ligands while mutual trans influence by the phosphine ligands induces significant elongation of the Ru(III)-P bonds. Cyclic voltammograms of the cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2]+ complexes in dichloromethane solution exhibited typical dual redox signals corresponding to the cis-[Ru(ROCS2)2(PPh3)2](+/0) (ca. +0.15 and +0.10 V vs ferrocenium/ferrocene couple for R = Et and iPr, respectively) and to trans-[Ru(ROCS2)2(PPh3)2](+/0) (-0.05 and -0.15 V vs ferrocenium/ferrocene for R = Et and iPr, respectively) couples. Analyses on the basis of the Nicholson and Shain's method revealed that the thermal disappearance rate of transient trans-[Ru(ROCS2)2(PPh3)2] was dependent on the concentration of PPh3 in the bulk: the rate constant for the intramolecular isomerization reaction of trans-[Ru(iPrOCS2)2(PPh3)2] was determined as 0.338 +/- 0.004 s(-1) at 298.3 K (deltaH* = 41.8 +/- 1.5 kJ mol(-1) and deltaS* = -114 +/- 7 J mol(-1) K(-1)), while the dissociation rate constant of coordinated PPh3 from the trans-[Ru(iPrOCS2)2(PPh3)2] species was estimated as 0.113 +/- 0.008 s(-1) at 298.3 K (deltaH* = 97.6 +/- 0.8 kJ mol(-1) and deltaS* = 64 +/- 3 J mol(-1) K(-1)), by monitoring the EC reaction (electrode reaction followed by chemical processes) at different concentrations of PPh3 in the bulk. It was found that the trans to cis isomerization reaction takes place via the partial dissociation of iPrOCS2(-) from Ru(II), contrary to the previous claim that it takes place by the twist mechanism.  相似文献   

14.
Microporous NaY zeolite is a common support of Cu catalysts for oxidative carbonylation of methanol, but the dispersion of Cu species on NaY is usually subjected to its micropore size. Here, ordered mesoporous KIT-6 was employed as the support for Cu catalyst and Al was incorporated into its framework to increase the surface acidity, which eventually improves the surface exchange capacity and Cu dispersion. The evolution of the state of Cu species on KIT-6 was analyzed combined with control of Cu loading. The physicochemical properties of the supports and corresponding catalysts were characterized by N2 adsorption–desorption, X-ray diffraction, ammonia temperature programmed desorption, Fourier transform infrared spectra, transmission electron microscopy, hydrogen temperature programmed reduction, and X-ray photoelectron spectroscopy. It was found that mesoporous KIT-6 showed better Cu dispersion than microporous NaY zeolite. Agglomerated CuO, dispersed CuO, and Cu2+ are the major Cu species observed on the catalyst surface. The increased surface acidic sites of KIT-6 by Al incorporation promoted the formation of Cu2+ and dispersion of CuO. With the increase in Cu loading, the Cu2+ content in the catalyst was decreased gradually along with increase in the bulk CuO. It was speculated that some exchanged Cu2+ could be transformed into highly dispersed CuO and even bulk CuO after calcination at a high Cu loading. Combined with the catalyst evaluation results, it was deduced that highly dispersed Cu2+ and CuO particles play significant roles in catalytic activity. The catalyst Cu/Al-K-10 achieved the highest space time yield of dimethyl carbonate of 135.4 mg/(g·h), which is 2.7 times the Cu/K-10 owing to its more dispersed Cu species. This laid the basis for preparing highly dispersed Cu species on mesoporous silica supports.  相似文献   

15.
Formic acid(FA), which can be produced via CO2reduction and biomass conversion, has received extensive interest as a convenient and safe hydrogen carrier due to its wide range of sources, renewable,high hydrogen content(4.4 wt%), and convenient storage/transportation. Designing highly efficient catalysts is the main challenge to realize the hydrogen production from FA. In this work, well-dispersed and electron-rich Pd Ir alloy nanoparticles with a size of 1.8 nm are confined in amino-modified 3D...  相似文献   

16.
Oxidative desulfurization (ODS) of organic compounds containing sulfur element from a model oil was performed using tungsten oxide catalysts supported on mesoporous silica with cubic Ia3d mesostructure, well-defined mesopores (7.2 nm), high surface area (719 m2/g), and three-dimensional pore network (WO x /KIT-6). The prepared WO x /KIT-6 catalysts (5–20 wt% WO x ) were characterized by X-ray diffraction analysis, N2 sorption measurements, electron microscopy, H2-temperature programmed reduction, Raman spectroscopy, and thermogravimetric analysis. Among the mesoporous catalysts, 10 wt% WO x /KIT-6 exhibited the best catalytic performance. Sulfur-containing organic compounds, such as dibenzothiophene, 4,6-dimethyldibenzothiophene, and benzothiophene, were completely (100 %) removed from the model oil over 10 wt% WO x /KIT-6 catalyst in 2 h. In addition, the catalyst could be reused several times with only slight decrease in catalytic activity.  相似文献   

17.
苯乙烯侧链C=C的选择性氧化一直是烯烃环氧化研究领域关注的热点之一.近几十年来,苯乙烯环氧化研究主要集中于多相过渡金属催化剂的开发与应用;以铜为主要活性物种的催化剂因具有较高的环氧苯乙烷选择性而备受瞩目.然而,采用pH调节法将铜离子引入三维六方介孔材料KIT-6阵列尚未见报道,尤其是pH值对合成材料的形貌、结构以及催化活性的影响尚未可知.基于此,本文采用pH调节法合成了铜嵌入KIT-6介孔材料Cu-KIT-6x(x代表初始溶胶的pH值,x=1.43,2.27,3.78,3.97,4.24,6.62),并将其应用于苯乙烯环氧化反应.采用X射线粉末衍射、氮气吸附脱附、透射电子显微镜以及X射线光电子能谱等手段对Cu-KIT-6x的表面结构及形貌进行了细致表征.结果表明,随着pH的变化,Cu-KIT-6x催化剂的物理特性、表面结构尤其是铜物种种类和含量均变化较大.较低的pH导致铜物种主要以Cu2+形式存在,难以引入到KIT-6骨架中,且不利于介孔材料的合成,最终导致产生无序介孔结构.当pH增大到3.78时,约有4.6 wt%的Cu(II)以?Cu?O?Si?形式成功引入KIT-6骨架中,获得了具有较高比表面积且有序的孔结构.此外,由于Cu2+的引入,骨架内部分Si4+被取代,促使Cu-KIT-63.78拥有可与载体KIT-6相媲美的大孔径.然而,当pH继续增大时,过量的Cu2+从KIT-6骨架中析出,以CuO形式存在于载体表面,从而导致Cu-KIT-6的孔径逐渐增大;同时NaOH对三维立方介孔结构的破坏,使得介孔结构坍塌及比表面积显著降低.以苯乙烯环氧化反应评价了Cu-KIT-6x系列催化剂的催化活性.当以叔丁基过氧化氢为氧化剂,乙腈为溶剂,在70 oC反应6 h后,Cu-KIT-63.78表现出最优的苯乙烯转化率(43.5%)及环氧苯乙烷选择性(86.6%).使用4次后,Cu-KIT-63.78展示了稳定的苯乙烯转化率、环氧苯乙烷选择性及有序的孔结构,充分表明其具有出色的稳定性.各表征结果揭示了在适宜pH下合成的Cu-KIT-63.78催化剂具有较高的铜含量、有序的立方Ia3d介孔结构及合适的结构参数,因而在苯乙烯环氧化反应中表现优异活性和良好稳定性.  相似文献   

18.
Neutral and cationic mononuclear complexes containing both group 15 and polypyridyl ligands [Ru(kappa3-tptz)(PPh3)Cl2] [1; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine], [Ru(kappa3-tptz)(kappa2-dppm)Cl]BF4 [2; dppm=bis(diphenylphosphino)methane], [Ru(kappa3-tptz)(PPh3)(pa)]Cl (3; pa=phenylalanine), [Ru(kappa3-tptz)(PPh3)(dtc)]Cl (4; dtc=diethyldithiocarbamate), [Ru(kappa3-tptz)(PPh3)(SCN)2] (5) and [Ru(kappa3-tptz)(PPh3)(N3)2] (6) have been synthesized. Complex 1 has been used as a metalloligand in the synthesis of homo- and heterodinuclear complexes [Cl2(PPh3)Ru(micro-tptz)Ru(eta6-C6H6)Cl]BF4 (7), [Cl2(PPh3)Ru(mu-tptz)Ru(eta6-C10H14)Cl]PF6 (8), and [Cl2(PPh3)Ru(micro-tptz)Rh(eta5-C5Me5)Cl]BF4 (9). Complexes 7-9 present examples of homo- and heterodinuclear complexes in which a typical organometallic moiety [(eta6-C6H6)RuCl]+, [(eta6-C10H14)RuCl]+, or [(eta5-C5Me5)RhCl]+ is bonded to a ruthenium(II) polypyridine moiety. The complexes have been fully characterized by elemental analyses, fast-atom-bombardment mass spectroscopy, NMR (1H and 31P), and electronic spectral studies. Molecular structures of 1-3, 8, and 9 have been determined by single-crystal X-ray diffraction analyses. Complex 1 functions as a good precursor in the synthesis of other ruthenium(II) complexes and as a metalloligand. All of the complexes under study exhibit inhibitory effects on the Topoisomerase II-DNA activity of filarial parasite Setaria cervi and beta-hematin/hemozoin formation in the presence of Plasmodium yoelii lysate.  相似文献   

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