Deactivation of silica supported Pd catalysts during liquid-phase hydrogenation

Summary Large pore MCM-41 was found to provide a better stabilization of Pd particles than amorphous SiO₂ during liquid phase hydrogenation. Pd/large pore MCM-41 exhibited higher hydrogenation activities as well as lower amount of metal loss by Pd leaching.     

Synthesis of polyphenylacetylene free-standing films in the presence of rhodium–imidazole catalysts

A new dinuclear rhodium(I) complex [Rh₂(cod)₂(imH)₂im]PF₆ (I) has been synthesized and characterized. The complex is unstable in solution where it undergoes modifications leading to insoluble oligomers. However, it exhibits high catalytic activity towards polymerization of phenylacetylene (PPA) films can be obtained under mild reaction conditions. As-grown PPA films are stable and soluble. Two different types of morphologies were found: one exhbits a cell-like structure with microfibrils inside the cell and the other a dense enamel-like smooth surface.     

铱基催化1-已烯氢甲酰化反应的研究

自1938年Otto Roelen从事Fisher-Ttopsch发现氢甲酰化反应以来,这类反应一直是有机合成和金属催化领域热点之一。目前合成醛及其衍生物的氢甲酰化反应已成为金属均相催化体系中使用可溶性催化剂最大的工业应用范例。而自20世纪90年代出现的Cativa(铱基催化剂),因具有原料价格低,稳定性好,易溶解,     

Rhodium complexes with dioximes as catalysts of hydroformylation and hydrogenation of 1-hexene

Rhodium(II) complexes with dioximes [Rh(Hdmg)₂(PPh₃)]₂ [I] (Hdmg=monoanion of dimethylglyoxime) and [Rh(Hdmg)(ClZndmg)(PPh₃)]₂ [II] catalyse hydroformylation and hydrogenation reactions of 1-hexene at 1 MPa CO/H₂ and 0.5 MPa H₂ at 353 K, respectively. Hydroformylation with complex [I] produces 94% of aldehydes (n/iso=2.2) and 6% 2-hexene whereas the second catalyst [II] gives ca. 40% of aldehydes (n/iso=2.1) and 60% of 2-hexene. Corresponding Rh(III) complexes are inactive in hydroformylation except of RhH(Hdmg)₂(PPh₃) [III], which shows activity similar to [I]. Complexes [Rh(Hdmg)₂(PPh₃)]₂ [I], [Rh(Hdmg)(ClZndmg)(PPh₃)]₂ [II], RhH(Hdmg)₂(PPh₃) [III] and [Rh(Hdmg)₂(PPh₃)₂]ClO₄ [V] catalyse 1-hexene hydrogenation with an average TON ca. 18 cycles/mol [Rh]×min. Complex [II] has also been found to catalyse hydrogenation of cyclohexene, 1,3-cyclohexadiene and styrene.     

Preparation and characterization of ultrafine Fe-Cu-based catalysts for CO hydrogenation

The ultrafine particles of a new style Fe-Cu-based catalysts for CO hydrogenation were prepared by impregnating the organic sol of Fe（OH）3 and Cu（OH）2 onto the activated Al2O3, in which the organic sol of Fe（OH）3 and Cu（OH）2 were prepared in the microemulsion of dodecylbenzenesulfonic acid sodium（S）/n-butanol（A）/toluene（O）/water with V（A）/V（O） = 0.25 and W（A）/W（S） = 1.50. This catalyst was characterized by particle size analysis, XRD and TG. The results of particle size analysis showed that Fe（OH）3 particles with a mean size of 17.1 nm and Cu（OH）2 particles with an average size of 6.65 um were obtained. TG analysis and XRD patterns suggested that 673 K is the optimal calcination temperature. CO hydrogenation produced C＋OH with a high selectivity above 58 wt% by using the ultrafine particles as catalyst, and the total alcohol yield of 0.250 g·ml^-1 ·h^-1 was obtained when the contents of Al2O3 and K were 88.61 wt% and 1.60 wt%, respectively.     

Rhodium(I) complexes with 1′-(diphenylphosphino)ferrocenecarboxylic acid as active and recyclable catalysts for 1-hexene hydroformylation

The rhodium complex trans-[Rh(CO)(Hdpf-κP)(dpf-κ²O,P)] (1), (Hdpf = 1′-(diphenylphosphino)ferrocenecarboxylic acid) was used as an efficient and recyclable catalyst for 1-hexene hydroformylation producing ca. 80% of aldehydes at 10 atm CO/H₂ and 80 °C. After the reaction, unchanged complex 1 was separated from the reaction mixture and used again three times with the same catalytic activity. The effect of modifying ligands, phosphines and phosphites, on the reactivity of 1 was investigated. The active catalytic systems containing 1 or trans-[Rh(CO)(L)(dpf-κ²O,P)] (2) were formed in situ from acetylacetonato rhodium(I) precursors [Rh(CO)₂(acac)] (3) or [RhL(CO)(acac)] (4) and Hdpf or Medpf (L = phosphine, Medpf = methyl ester of Hdpf).     

Preparation of rhodium catalysts on laminar and zeolitic structures by anchoring of organometallic rhodium

Rhodium catalysts supported on six different aluminosilicate structures were prepared by hydrogen reduction of a cationic organometallic rhodium complex anchored to the support. The precursor active phase was incorporated in acetone medium through ion exchange using [Rh(Me₂CO)_x(NBD)]ClO₄ as the metal precursor species, in which NBD is 2,5‐norbornadiene and (Me₂CO)_x is acetone. The effect of the structure and characteristics of the support on metal load and dispersion was studied in the heterogeneous catalysts thus prepared. The supports were characterized by X‐ray diffraction, energy‐dispersive X‐ray analysis, volumetric adsorption and surface acidity. For the precursors and catalysts, the metal load was determined by UV–VIS spectra, the reduction temperature was determined by differential scanning calorimetry, and rhodium dispersion was measured by chemisorption. The structure of the materials used as supports had a great influence on the catalyst prepared. A higher metal content was achieved in the supports with laminar structures, whereas better dispersion was shown by the catalysts supported on zeolitic structures. Copyright © 2001 John Wiley & Sons, Ltd.     

层状K/Mg-Fe-Al催化剂的制备及其CO加氢性能研究

采用共沉淀法制备了系列不同Mg/Fe/Al配比MgFeAl-HTLcs前驱体,经焙烧、浸渍K改性、二次焙烧后用于CO加氢反应。采用N2吸附-脱附、SEM、TG、XRD、H2-TPR、XPS等手段对催化剂进行了表征。结果表明,共沉淀法制备的不同配比MgFeAl-HTLcs类水滑石前躯体均具有典型层状结构;焙烧后生成MgO、Fe2O3以及少量MgFeAlO4物相,三组元间相互作用增强,反应后以MgCO3和Fe3O4物相为主,同时出现较弱的Fe5C2相;K改性后发生结构重构,热稳定性增强,且随Al含量增加,比表面积显著单调下降;与K/Mg-Fe相比,K/Mg-Fe-Al样品中Fe2O3到Fe3O4的还原受到抑制;二次焙烧后,反应前表面相对富Fe,反应后表面富K。在CO加氢反应中,K/Mg-Fe-Al系列催化剂均表现出较高的反应活性以及烯烃选择性,随Fe/Al配比相对增加,C5+含量呈降低趋势,O/P值增加;与K/1.5Mg-0.67Fe相比,K/1.5Mg-0.67Fe-0.33Al催化剂C5+含量由22.17%降至10.90%,C=2-4含量由40.98%提高至47.28%。     

Application of [BoPhoz Rh] catalysts in the asymmetric hydrogenation of a pyridyl benzothiophene alkene

The asymmetric hydrogenation of a pyridyl benzothiophene alkene has been successfully accomplished using [BoPhoz Rh] catalysts. By tailoring the steric properties of the BoPhoz ligand, the ee of the product could be increased from just 12% to 90%. This research further expands the substrate scope of the conventional class of functionalized alkenes amenable to catalytic asymmetric hydrogenation.     

Preparation and catalytic performance of monolayer-dispersed Pd/Ni bimetallic catalysts for hydrogenation

Pd/Ni bimetallic catalysts were prepared by replacement reactions, characterized by X-ray diffraction, CO chemisorption and H₂ temperature-programmed desorption, and evaluated for hydrogenation of cyclohexene, styrene and acetone. The results show that Pd atoms are monolayer-dispersed on the Ni surface in these Pd/Ni catalysts. Consequently, Pd/Ni catalysts are much more active than Pd/Ni and Pd/c-Al₂O₃ with the same Pd loading prepared by the conventional impregnation method. __________ Translated from Chinese Journal of Catalysis, 2007, 28(8): 676–680 [译自: 催化学报]     

Analysis of microstructure of ethylene–1-hexene copolymer prepared over thermally pretreated MgCl2/THF/TiCl4bimetallic catalyst

Thermally pretreated catalysts were prepared by heating MgCl₂/THF/TiCl₄ (TT-0) at 80°C for 5 min (TT-1) and 60 min (TT-2), and at 108°C for 5 min (TT-3) and 60 min (TT-4). Ethylene–1-hexene copolymers were prepared with these catalysts. The TT-1 catalyst produced more blocky and higher 1-hexene content polymer than TT-0, 2, 3, and 4. Temperature rising elution fractionation (TREF) analysis was used to investigate the chemical composition distribution of the ethylene–1-hexene copolymer, exhibiting bimodal distribution for TT-0 and trimodal for TT-1, 2, 3, and 4. A portion of higher hexene content of the copolymer markedly increased when the copolymerization was performed with TT-1, indicating that copolymerization active sites were newly generated. Portion of homopolyethylene increased drastically when the copolymerization was performed with TT-4, indicating that ethylene homopolymerization active sites were increased. Gel permeation chromatography (GPC) also revealed that three kinds of active sites existed on the catalyst. ¹³C-NMR spectrum of each fraction after TREF analysis suggested that the isospecific active site could polymerize 1-hexene well, resulting in random and alternating copolymers. A scheme for generation of the active site and change of its nature during thermal treatment of bimetallic complex catalyst is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 291–300, 1998     

Palladium catalysts supported on oligomeric aramides in the liquid-phase hydrogenation of phenylacetylene

The catalytic behaviour of palladium supported on oligomeric aramides has been investigated in the liquid phase selective hydrogenation of phenylacetylene to styrene, by comparison with conventional Pd-supported systems, such as Pd/carbon. Pd/Al₂O₃ and Pd/SiO₂. The influences of the reduction temperature and metal loading on the activity/selectivity behaviour of the title reaction are explained in terms of different reducibility patterns of the catalysts, as well as in the light of a peculiar support effect of the organic matrix on Pd particles.     

Cu/MgO催化剂的MOCVD法制备及其γ-戊内酯加氢制1,4-戊二醇性能

以Cu（acac）₂为金属有机铜前体,层状MgO为载体,采用金属有机化学气相沉积方法（MOCVD）制备了Cu/MgO催化剂,并通过X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、场发射扫描电镜（FE-SEM）、透射电子显微镜（TEM）和N₂物理吸附等方法对Cu/MgO催化剂结构进行表征。结果表明,有机铜前体沉积在了MgO上,并且在沉积后,载体MgO的晶体结构仍然保留完整。利用生物质平台分子γ-戊内酯加氢反应来评价Cu/MgO催化剂的催化性能。研究表明,在473 K和10 MPa反应条件下,18% Cu/MgO催化剂表现出优异的催化活性（90.5%）和1,4-戊二醇选择性（94.4%）,且催化剂循环三次,催化活性没有显著降低。     

Soluble metal–polymer catalysts in the hydrogenation of organic compounds

Literature describing the use of soluble metal–polymer catalysts in the molecular hydrogenation of alkenes, alkynes, aromatic and heterocyclic compounds has been reviewed. Special attention has been paid to coordinated metallic and organometallic catalytic systems and highly dispersed colloidal metals stabilized with polymers. The influence of metals, polymers and solvents on the structures of active sites is discussed. The prospects for the application of soluble metal–polymer catalysts in organic synthesis are also considered.     

脂肪酸加氢改性Ni及Ni-Pd催化剂的制备

工业动植物油脚的主要成分为不饱和脂肪酸,通过催化加氢制得的硬脂酸[1,2],可作橡胶添加剂。但不饱和脂肪酸的酸值较高,易使镍催化剂皂化中毒而失活。本文在镍催化剂的基础上,加入微量的过渡或碱士等活泼金属作助剂,提高催化剂的抗皂化性能;加入微量钯,提高催化剂的活性,采用沉淀法,以硅藻土为载体,制备了负载型改性Ni及Ni Pd催化剂。并与国内化工企业常用的棕榈酸(酸值为188 6mgKOH/g)进口加氢催化剂USA 140和USA 110在相同条件下对进行对比。1　实验部分1 1　催化剂制备将18gNi(NO3)2:6H2O溶于130ml水,再依次加入一定配比的过…     

Studies of Intermolecular Heterogeneity Distribution in Ethylene/1-hexene Copolymers Using DSC Method

The investigation of the intermolecular composition distribution of an ethylene/1-hexene copolymers using DSC method has been carried out. The known methods: step crystallization (SC) and successive self-nucleation/annealing (SSA) have been adapted for this purpose, and particularly, the optimal condition of the process have been chosen to enable the best fractional crystallization of the copolymer. The method has been applied for fractionation of two ethylene/1-hexenecopolymers synthesized with supported vanadium and zirconocene catalysts and having similar concentrations of 1-hexene. Although metallocene catalysts are known from their more homogeneous structure of active sites in comparison to multi-site Ziegler–Natta catalysts, the copolymers obtained over both catalytic systems gave DSC curves resolved into several peaks but with different melting points. Using the Thomson–Gibbs equation, comparable average lamellar thickness of the separated peaks has been calculated. The amounts of copolymer fraction with defined lamellar thickness have been determined. It was obtained that the copolymer produced from the metallocene system contains a thinner and more homogeneous lamella thickness than that obtained with Ziegler–Natta vanadium catalyst supported on the same carrier. This revised version was published online in August 2006 with corrections to the Cover Date.     

低碱度共沉淀法制备苯选择加氢Ru-Zn催化剂

在低碱度下采用共沉淀法成功制备了非负载型Ru-Zn催化剂,用于苯选择加氢制环己烯反应.固定氢氧化钠沉淀剂的量,考察了不同氯化锌加入量对催化剂结构和催化性能的影响,采用N2吸附、X射线衍射和程序升温还原等手段对催化剂进行了表征.同时考察了选用具有最佳锌含量的Ru-Zn催化剂时搅拌速度和硫酸锌添加剂等对催化反应性能的影响,最后考察了催化剂多次使用时的反应性能.研究表明, Zn含量16.7%(质量分数)的Ru-Zn催化剂具有最佳的催化性能;在ZnSO4水溶液(0.45 mol/L)中,优化反应条件(哈氏合金釜,1200 r/min,150oC, H2压5 MPa)下反应45 min,苯转化率57%时环己烯选择性可达80%(收率超过45%).钌催化剂中ZnO晶体对于环己烯选择性达到80%非常重要.催化剂回收循环反应5次时反应性能基本不变,表明低碱度下制备的催化剂具有良好的稳定性,显示了工业化应用前景.     

低碱度共沉淀法制备苯选择加氢Ru-Zn催化剂

在低碱度下采用共沉淀法成功制备了非负载型Ru-Zn催化剂,用于苯选择加氢制环己烯反应.固定氢氧化钠沉淀剂的量,考察了不同氯化锌加入量对催化剂结构和催化性能的影响,采用N2吸附、X射线衍射和程序升温还原等手段对催化剂进行了表征.同时考察了选用具有最佳锌含量的Ru-Zn催化剂时搅拌速度和硫酸锌添加剂等对催化反应性能的影响,最后考察了催化剂多次使用时的反应性能.研究表明, Zn含量16.7%(质量分数)的Ru-Zn催化剂具有最佳的催化性能;在ZnSO4水溶液(0.45 mol/L)中,优化反应条件(哈氏合金釜,1200 r/min,150oC, H2压5 MPa)下反应45 min,苯转化率57%时环己烯选择性可达80%(收率超过45%).钌催化剂中ZnO晶体对于环己烯选择性达到80%非常重要.催化剂回收循环反应5次时反应性能基本不变,表明低碱度下制备的催化剂具有良好的稳定性,显示了工业化应用前景.     

CO加氢制备低碳烯烃Fe基、Co基催化剂研究进展

CO加氢制备低碳烯烃是非石油路线获得烯烃的重要反应,其反应路线有直接法和间接法。直接法制备低碳烯烃具有反应路线短、能源利用率高、经济高效等优势。综述了近年来Fe基催化剂、Co基催化剂在CO直接制备低碳烯烃中的研究进展。分析认为：费托合成过程产物选择性遵循Anderson-Schulz-Flory（ASF）分布规律,助剂和载体的使用一定程度提高Fe基、Co基催化剂的低碳烯烃选择性。     

Enhanced catalytic performance of Pd‐Ga bimetallic catalysts for 2‐ethylanthraquinone hydrogenation

A series of Pd and Pd‐Ga bimetallic catalysts were prepared by a co‐impregnation method for 2‐ethylanthraquinone (EAQ) hydrogenation to produce hydrogen peroxide. Compared with 0.6Pd catalyst, the hydrogenation efficiency of 0.6Pd1.2Ga catalyst (11.9 g L^?1) increases by 32.2%, and the stability of 0.6Pd1.2Ga catalyst is also higher than that of 0.6Pd catalyst. The structures of the samples were determined by N₂ adsorption–desorption, ICP, XRD, CO chemisorption, TEM, H₂‐TPR, in situ CO‐DRIFTS and XPS. The results suggest that incorporation of Ga species improves Pd dispersion and generates a strong interaction between Ga₂O₃ and Pd interface or between Pd and support. DFT calculation results indicate that the strong adsorption of carbonyl group on Ga₂O₃/Pd interface facilitates the activation of EAQ and promotes the hydrogenation efficiency.