镍配合物催化乙烯齐聚和聚合的进展

继SHOP催化体系采用镍配合物催化乙烯齐聚制备端烯烃在研究和应用中获得成功以来,由于后过渡金属上容易产生β-氢消除反应,镍配合物催化乙烯的研究搁置了近二十年。然而,近十年里,镍配合物催化乙烯齐聚和聚合研究再次受到催化剂研究者的重视,进入了飞速发展的新时期。本文综述近三年间这个领域的发展,特别是我国学者在这个领域的贡献,展示了镍配合物在乙烯齐聚和乙烯聚合制备支化聚烯烃中的巨大潜力,促进该领域研究的发展。     

Mesoporous Nickel–Alumina Catalysts for Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG)

Recent progress on the mesoporous nickel–alumina catalysts for hydrogen production by steam reforming of liquefied natural gas (LNG) was reported in this review. A number of mesoporous nickel–alumina composite catalysts were prepared by a single-step surfactant-templating method using cationic, anionic, and non-ionic surfactant as structure-directing agents for use in hydrogen production by steam reforming of LNG. For comparison, nickel catalysts supported on mesoporous aluminas were also prepared by an impregnation method. The effect of preparation method and surfactant identity on physicochemical properties and catalytic activities of mesoporous nickel–alumina catalysts in the steam reforming of LNG was investigated. Regardless of preparation method and surfactant identity, nickel oxide species were finely dispersed on the surface of mesoporous nickel–alumina catalysts through the formation of surface nickel aluminate phase. However, nickel dispersion and nickel surface area of mesoporous nickel–alumina catalysts were strongly affected by the preparation method and surfactant identity. It was found that nickel surface area of mesoporous nickel–alumina catalyst served as one of the important factors determining the catalytic performance in hydrogen production by steam reforming of LNG. Among the catalysts tested, a mesoporous nickel–alumina composite catalyst prepared by a single-step non-ionic surfactant-templating method exhibited the best catalytic performance due to its highest nickel surface area.     

镍盐前驱体对Ni/C催化剂乙醇气相羰化活性的影响

采用等体积浸渍法制备了分别以乙酰丙酮镍、氯化镍、硝酸镍和醋酸镍为前驱体负载在活性炭上的四种催化剂。用BET、金属分散度、H2-TPR、CO-TPD和XRD等方法研究了四种催化剂的结构特点和乙醇气相羰化活性。结果表明,以醋酸镍制备的Ni/C催化剂的羰化活性最高,乙醇转化率和丙酸选择性分别为96.1%和95.7%,而以乙酰丙酮镍制备的Ni/C催化剂的羰化活性最低,乙醇转化率和丙酸选择性分别为68.9%和27.1%。这种活性的差异与镍盐前驱体和活性炭之间的相互作用强弱有着密切关系。醋酸镍组分与活性炭之间的相互作用较强,浸渍组分易在活性炭表面充分吸附,活性中心Ni0在240－340 ℃温度范围内对CO吸附量最大,还原后金属镍的分散度较好且晶粒较小。     

固相浸渍法制备NiO/CeO2催化剂及其在CO氧化反应中的应用

采用固相浸渍法制备了一系列NiO/CeO2催化剂,并通过与常规湿浸渍法比较,考察了制备方法对催化剂和CO氧化反应性能的影响.同时结合X射线衍射(XRD),N2吸附-脱附(BET),透射电镜(TEM),氢气-程序升温还原(H2-TPR),拉曼(Raman)光谱,X射线光电子能谱(XPS)等手段对催化剂的结构和表面物种分散状态进行了表征.CO氧化活性测试结果表明,当镍负载量相同时,固相浸渍法制备的催化剂相比于湿浸渍法表现出更好的催化性能.TEM、XPS、H2-TPR结果表明,固相浸渍法更有利于加强镍铈间的相互作用和得到高分散的镍物种,从而促进镍物种的还原.Raman结果表明固相浸渍法相比于湿浸渍法能产生更多氧空位,这有利于氧气在催化剂表面的活化,使得CO氧化反应更容易进行.     

Vergleichende Untersuchungen zur katalytischen Aktivität von Nickel und kristallinen Nickelboriden sowie RANEY-Nickel und borhaltigem RANEY-Nickel: Hydrierungs- und Dehydrierungsreaktionen,elektrochemische Methanoloxydation

The catalytic activation of the decomposition of gaseous formic acid with nickel powder and crystalline nickel borides is compared. Only after treatment with NH₃-solution the activity of the nickel borides has the same order as that of nickel powder. Ni₃B is the best of the catalysts used. The crystalline nickel borides cannot catalyze the anodic oxydation of methanol in alcaline solution at 80°C. — Nickel catalysts containing Boron can be prepared by the RANEY method from nickel boride and aluminum. These catalysts have the same activity as normal RANEY nickel with respect to the hydrogenation of the C?C? bond in crotonic acid; they are more active with respect to the C?O? bond of acetone. Methanol can be oxydised fastly in alcaline solution at 80°C on electrodes containing RANEY nickel. RANEY nickel containing boron is still better.     

Reinforced nickel and nickel-platinum catalysts for performing the thermally coupled reactions of methane steam reforming and hydrogen oxidation

The formation of composite nickel and nickel-platinum catalysts reinforced with steel gauze was studied. The catalysts were prepared by sintering powdered nickel metal and a supported nickel catalyst (GIAP-3 or NIAP-18) with a chromium oxide additive in the case of nickel-containing composite catalysts or by sintering powdered nickel, aluminum, and a supported platinum catalyst in the case of catalysts containing nickel-platinum. With the use of electron microscopy, mercury porosimetry, and X-ray electron probe microanalysis, it was found that a metal matrix, in the pores of which supported catalyst particles were distributed, was formed in the composite catalysts. The reinforced nickel catalysts prepared were active in the reaction of methane steam reforming, and the catalysts containing nickel-platinum were active in the reaction of hydrogen oxidation. An increase in the activity of reinforced nickel catalysts in the course of the reaction was found. It is believed that the increase of the activity was due to the reduction of nickel oxide from an inactive difficult-to-reduce oxide film containing nickel and chromium oxides under the action of the reaction atmosphere.     

Support Modification of Supported Nickel Catalysts for Hydrogen Production by Auto-thermal Reforming of Ethanol

Recent progress on support modification of supported nickel catalysts for hydrogen production by auto-thermal reforming of ethanol was reported in this review. Nickel catalysts supported on various materials, including metal oxides and metal oxide-stabilized mesoporous zirconias, were prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. Various experimental measurements such as NH₃-TPD (temperature-programmed desorption) and TPR (temperature-programmed reduction) were carried out to elucidate the different catalytic performance of supported nickel catalysts. It was revealed that acid property of supporting materials served as one of the important factors determining the catalytic performance. Hydrogen yield over nickel catalysts supported on metal oxides showed a volcano-shaped curve with respect to acidity of the supports. Among the catalysts tested, Ni/ZrO₂ catalyst with an intermediate acidity exhibited a superior catalytic performance. It was also observed that reducibility of nickel catalysts supported on metal oxide-stabilized mesoporous zirconias played a key role in determining the catalytic performance in the auto-thermal reforming of ethanol for hydrogen production. Hydrogen yield over nickel catalysts supported on metal oxide-stabilized zirconias increased with increasing reducibility of the catalysts (with decreasing TPR peak temperature of the catalysts).     

NiO/γ-Al2O3催化剂中NiO与γ-Al2O3间的相互作用

利用溶胶－凝胶法制备了不同含量的 ＮｉＯ／γ－Ａｌ_２Ｏ_３催化剂,通过ＸＲＤ,ＸＰＳ和 ＴＰＲ等技术考察了制备方法、ＮｉＯ含量和焙烧温度对催化剂结构和Ｎｉ存在状态的影响,发现溶胶－凝胶法制备的催化剂活性组分ＮｉＯ与担体γ－Ａｌ_２Ｏ_３间具有强相互作用．详细地讨论了Ｎｉ物种的还原状态与以“Ｎｉ~０”为活性中心的催化反应的活性之间的关系．溶胶－凝胶法制备的催化剂经高温焙烧后,Ｎｉ以一种类尖晶石结构的固溶体形式存在,这种固溶体态尖晶石可能会抑制Ｎｉ的烧结和流失,提高催化剂的稳定性．     

Etude de l'obtention d'enoxysilanes par action du triethylsilane sur des cetones enolisables,aliphatiques ou cyclaniques,en presence de catalyseurs au nickel

The preparion of alkoxysilanes and alkenoxysilanes has been achieved by the reaction of enolizable aliphatic or cyclic ketones with triethylsilane in the presence of nickel catalysts. For some catalysts, the reaction can be directed to give exclusively one or the other of these derivatives. The use of certain nickel catalysts gives very high yields of alkenoxysilanes, and this has been closely investigated.     

Study on Ni/C catalysts for vapor phase carbonylation of ethanol

Activated carbon-supported Ni catalysts for vapor phase carbonylation of ethanol to propionic acid in the presence of ethyl iodide as promoter were investigated. Under optimum reaction conditions, the conversions of carbon monoxide and ethanol were measured to be 81.4% and 98.4%, respectively, while the selectivity for propionic acid was found to be 98.65%. The catalyst was stable within 48 h on stream. XRD and XPS methods were used to characterize the structures and surface properties of the fresh and tested catalysts. The characterization results indicated that aggregation of nickel particles and formation of nickel iodide on the catalyst surface should be responsible for the deactivation of the catalysts.     

漆原镍催化剂用于硝基化合物催化加氢

采用锌粉还原氯化镍制备了漆原镍催化剂,并将其用于催化间二硝基苯加氢制间苯二胺和2,5-二氯硝基苯加氢制2,5-二氯苯胺反应.运用X射线衍射、电感耦合等离子体发射光谱和透射电子显微镜等技术对催化剂进行了表征.考察了锌粉、展开剂和制备温度对催化剂活性的影响,以及压力、溶剂等对加氢反应速率的影响,确定了适宜的催化剂制备条件.结果表明,在间二硝基苯和2,5-二氯硝基苯加氢反应中,漆原镍催化剂表现出很高的活性和选择性,在乙醇溶剂中加入适量的水能够大大提高反应速率,适量的脱氯抑制剂能够有效加快2,5-二氯硝基苯加氢速率并提高2,5-二氯苯胺选择性.漆原镍催化剂重复使用5次后其性能基本保持不变.     

The Development and Use of New Hydrogenation Catalysts1

Advantages and drawbacks of commercial catalysts for gas-phase hydrogenation are considered. The use of modified catalysts, including nickel catalysts modified with heteropoly compounds, is promising. Data on the selective reduction of carbonyl compounds and hydrogenation of aromatic hydrocarbons over these catalysts are presented. Palladium films are shown to be the best catalysts for the selective reduction of acetylene compounds to olefins.     

Syndiotactic Polymerization of Propylene: Single‐Site Vanadium Catalysts in Comparison with Zirconium and Nickel

The syndiotactic‐specific polymerization of propylene can be promoted by single‐site catalysts based on vanadium, nickel and group IV metals. The polymerization mechanisms are reasonably well established for nickel and group IV metals. For vanadium catalysts the polymerization mechanisms reported in the literature are still debatable, since the stereochemistry of the monomer insertion is well known, but the active species have never been isolated. In this paper the mechanisms concerning Ni and group IV metal catalysts are briefly summarized and proposed mechanisms concerning vanadium are compared within one another.     

Tungsten Promoted Ni／Al2O3 Catalysts for Carbon Dioxide Reforming of Methane to Synthesis Gas

A series of tungsten promoted alumina supported nickel catalysts has been prepared for the carbon diox-ide reforming of methane to synthesis gas. The catalysts have been characterized by means of XRD, TEM,and Laser Raman spectroscopy. It is shown that the addition of tungsten to the nickel catalyst can stabilize the catalyst and increase the resistance to carbon deposition. Adding a suitable amount of tungsten can also increase the catalyst activity to be close to that of supported noble metal catalysts. The carburisation of the tungsten modified nickel catalyst decreases the catalyst activity at lower reaction temperatures (＜1123K),but has no effect on the catalyst performance at higher reaction temperatures. The alumina supported nickel catalyst modified by 0. 67% (mass fraction) WO3 has the equivalent equilibrium constant of the dry reforming reaction to that of alumina supported 5% (mass fraction) Ru at 873 K, and also has a lower activation energy for dry reforming than the latter.     

Study of nickel nanoparticles supported on activated carbon prepared by aqueous hydrazine reduction

Nickel nanoparticles were obtained by the reduction in hydrazine aqueous media of nickel acetate as a precursor supported on activated carbon of high surface area. Classical catalysts using nickel acetate or nitrate were prepared for comparison. The catalysts were characterized by N(2) physisorption, H(2)-TPR, H(2)-adsorption, TPD, TEM, and XRD, and tested in the gas phase hydrogenation of benzene. Hydrazine catalysts were found much more active in benzene hydrogenation than corresponding classically prepared catalysts. Remarkably, their reactivity is comparable (turn-over frequency of 0.2001-0.2539 s(-1) at 393 K) to that of Pt classical catalysts supported on activated carbon in the same conditions. Evidence is given for the existence of the hydrogen spillover effect in benzene hydrogenation, not reported before in the literature. As a result of the hydrogen spillover effect, catalysts performances can be explained by a combination of surface metal atom reactivity, metal-support interaction strength, and specific surface area extent. Maximum effect is observed with hydrazine preparation method, for 1% Ni content and nickel acetate as a precursor. Unexpectedly, it was also found that hydrazine preparation increases the specific area of the catalysts.     

镍配合物催化乙烯低聚/聚合的研究进展

催化乙烯低聚或聚合的镍配合物催化剂研究,不仅帮助提供探索乙烯配位聚合机理的催化剂模型,更为重要的帮助探讨不同催化剂模型下的催化剂活性和选择性,为工业界寻找具有潜在应用价值的高效催化剂奠定基础.同时,利用镍配合物催化剂容易导致所得聚烯烃树脂产生支链的特点,有望制备具有优异性能的支化聚烯烃树脂.本文综述了近年来镍配合物在乙烯低聚或聚合催化剂研究方面的进展,并特别强调了催化剂结构和催化性能之间的内在规律.     

Untersuchungen an Nickel-Zeolith-Trägerkatalysatoren. I. Herstellung und Charakterisierung von Nickel-Zeolith-Trägerkatalysatoren

By means of cation exchange nickel zeolites of the types A, X and Y were prepared with different (0.5–12.5% of weight) nickel, contents. Nickel zeolites of the A type up to 14% exchange and zeolites of the X type up to 27% exchange do not show changes in structure. Nickel zeolite catalysts were prepared by reduction of the nickel zeolites with hydrogen. Analyses of nickel metal in these catalysts showed that only part of the nickel cations is reduced. By means of hydrogen chemisorption it could be proved that the metallic nickel does not exist in atomic dispersion and is deposited on the external surface as well as inside the pores.     

[N,N]-二齿镍配合物催化烯烃聚合

烯烃聚合催化剂的设计是烯烃配位聚合领域的一个核心科学问题,通过设计合成精确结构的催化剂可以有效地调控催化聚合性能以及聚合产物的结构.后过渡金属催化剂由于其易调变性、对聚合产物支化结构的可控性及对极性单体的容忍性,在烯烃聚合领域引起了广泛的关注.本文介绍了近年来本课题组在[N,N]-二齿镍烯烃聚合催化剂设计方面的研究进展,包括四元环的中性脒基镍催化剂、五元环的-二亚胺镍催化剂、2-胺基吡啶和-胺基亚胺系列镍催化剂,以及六元环的-二亚胺和苯胺基亚胺镍催化剂在烯烃聚合的应用.通过优化后过渡金属镍催化剂结构,可成功实施烯烃活性聚合.     

Ethylene polymerization promoted by nickel complexes

The nickel complexes are of special relevance to catalysis for ethylene oligomerization and polymerization. Beyond the famous commercial SHOP process for ethylene oligomerization, among recent progress of nickel catalysts, various nickel complexes containing different ligands such as the bidentate and tridentate ligands are of interest. In contrast to the importance of hetereogeneous catalysis, the homogeneous catalyst is a small share for polyolefins, while the well-defined complexes affect the microstructure of the resultant polyolefin. The nickel catalysts often perform ethylene activations for inner olefins and the branched polyethylene with broad or bimodal molecular weight distribution. The catalytic behavior will be affected by adaptation of ligands coordinating around the nickel center. In addition, the auxiliary ligand Ph₃P can improve the catalytic activity by one order of magnitude, and its active center can be confirmed through isolating and characterizing the reliable intermediate. The text was submitted by the authors in English.     

漆原镍催化剂用于苯酚催化加氢

利用锌粉将NiCl₂液相还原制备漆原镍催化剂,考察了碱/酸活化方法、锌粉用量、还原温度、添加载体等条件下漆原镍催化苯酚加氢反应的性能。结果表明,锌粉还原的漆原镍催化剂可用NaOH或者乙酸活化处理,NaOH的效果优于乙酸。与不添加载体的催化剂相比,添加载体组分明显提高了金属镍的分散性和利用率。γ-Al₂O₃、CaCO₃、MgO均可作为漆原镍催化剂载体组分,而γ-Al₂O₃效果最好。还原剂锌粉用量、载体加入量过少或过多,都会造成催化剂活性降低,这与其影响金属镍的可接近性及分散性相关。无载体或加入载体的漆原镍催化剂均可在120~160 ℃催化苯酚加氢反应,主要产物为环己醇和环己酮,并以环己醇为主。