Al2O3负载镍基催化剂上CO2氢甲烷化研究

通过对Ni/Al2O3及添加CeO2的Ni/Al2O3催化剂上CO2氢甲烷化反应的研究发现，在反应过程中，该体系的催化剂上并不产生CO，添ＣeO2后能显著提高甲烷产率，原位漫反射红外光谱研究发现，甲烷可通过表面ＣＯ２^-物种加氢或表面甲酸盐加氢两种途径产生，且第二种途径更有效，添加 CeO2可通过在较低温度时形成较多的表面甲酸盐来提高ＣＯ２的甲烷化活性。     

Ni/MWCNT及镧改性Ni/MWCNT催化CO2甲烷化反应的性能

以多壁碳纳米管(MWCNT)为载体, 通过浸渍法制备了负载型镍催化剂和稀土镧改性的镍催化剂, 并对其二氧化碳甲烷化的催化性能进行了研究. 借助比表面积测试、程序升温还原(TPR)、X射线衍射(XRD)和X射线光电子能谱(XPS)等表征手段研究了稀土镧的添加对Ni/MWCNT催化剂结构和表面组成、催化剂还原性能以及CO₂甲烷化反应性能的影响. 结果表明: 稀土镧改性的Ni/MWCNT较Ni/MWCNT催化剂具有更好的CO₂甲烷化活性, 镧组分的加入提高了催化剂表面的镍物种浓度和分散度, 弱化了氧化镍与载体MWCNT之间的相互作用, 促进了氧化镍的还原, 同时提高了表面镍物种的电子密度, 增加了对反应物的吸附能力, 从而提高了其CO₂甲烷化活性. 制备过程中稀土镧的添加次序对催化性能有较明显的影响, 其活性顺序为先浸渍镧后浸渍镍制备的催化剂活性明显好于先浸渍镍后浸渍镧制备的催化剂.     

Methane Combustion Over Fe, Co and Ni Modified Manganese Oxide Catalysts

Fe-Mn, Co-Mn and Ni-Mn composite oxide catalysts based on high specific surface area MnO₂ precursor were prepared and applied to catalytic combustion of CH₄. Results were compared with that of unmodified MnOx and 1wt.% Pd/-Al₂O₃. Below 450°C, manganese oxide catalysts show higher activity than Pd/-Al₂O₃, while the modified manganese oxide catalysts exhibit higher activity than the unmodified one below 420°C. All catalysts were characterized by means of N₂-BET, XRD, TG-DTA and H₂-TPR. Due to the interaction between Fe, Co or Ni oxides and manganese oxide, the activity of the oxygen species of the modified catalysts is improved, which leads to the increase of their CH₄ combustion activity.     

二氧化碳-氧化环己烯的共聚反应

由CO2 -氧化环己烯 (CHO)配位催化共聚制得高Tg 的脂肪族聚环己基撑碳酸酯 ,并用IR、NMR和DSC等进行了表征 ,用TG对聚合物的热稳定性进行了分析。加入异氰酸苯酯有提高产物特性粘数的作用。     

Structure and Electrochemical Properties of Carbon Nanotubes Synthesized with Catalysts Obtained by Decomposition of Co,Ni, and Fe Polyoxomolybdates Supported by MgO

Carbon nanotubes (CNTs) were synthesized by thermal decomposition of methane at 900 °C using Co–Mo/MgO, Fe–Mo/MgO, and Ni–Mo/MgO catalysts. To obtain metallic nanoparticles, polyoxomolybdate clusters of Co, Ni, and Fe deposited on MgO were thermally decomposed at 700 °С, and the obtained oxides were heated in a carbon-containing atmosphere. The method of transmission electron microscopy (TEM) testified formation of one to ten walled CNTs with the average outer diameter depending on the catalyst used. Raman spectroscopy data confirmed the presence of single-walled CNTs in the samples obtained with Co–Mo/MgO and Fe–Mo/MgO catalysts. The electrochemical properties demonstrated by the obtained materials in supercapacitors are shown to be functions of their structural and compositional features.     

Electrocatalytic Study of Fe,Ni, Zr and Cu Complexes and Their Alumina Supported Catalysts

Russian Journal of Electrochemistry - The behavior of complexes of iron, nickel, zirconium and copper as an electrode in alkaline, acidic and neutral solution has been investigated primarily by...     

Low-Temperature Combustion Synthesis of Halloysite-Based Catalysts for the Deep Oxidation of Hydrocarbons and Carbon Monoxide and the Methanation of Carbon Dioxide

Kinetics and Catalysis - Supported mono- and bimetallic catalysts containing 10 wt % Ni(I), 10 wt % Co(II), and 5 wt % Co + 5 wt % Ni(III) on halloysite nanotubes have been synthesized by...     

Sm2(Fe,Al,Zr)17C1.5合金微结构与磁性能的关系

用Ｘ射线衍射仪,振动样品磁强计,扫描电镜及透射电镜对Ｓｍ２Ｆｅ１５．３Ｚｒ０．２Ａｌ１．５Ｃ１．５合金的微结构和磁性进行了研究。合金主要由２／１７相、α－Ｆｅ相和ＺｒＣ要组成。     

MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应

在密度泛函理论的B3LYP水平下计算了MH~+(M=Fe,Co,Ni)催化二氧化碳的氢化反应.研究表明,氢转移至C上要比转移至O上容易得多.探讨不同泛函方法对反应的影响,从CCSD(T)的计算结果可见,与Co H~+和Ni H~+相比,Fe H~+对H转移至C上的活性较高.电子结构分析表明,反应过程中氢转移为氢负离子转移.     

Magnetic and Thermal Properties of Novel Poly(ether-amide)/Fe3O4 Nanocomposite Containing Phosphine Oxide Group

New poly(ether-amide) nanocomposite containing phosphine oxide was prepared via solution polymerization process from synthesized poly(ether-amide) and Fe₃O₄ nanoparticles in a solution of N,N-dimethylformamide. Uniform monodisperse Fe₃O₄ nanoparticles were synthesized at room temperature via a facile sonochemical reaction. Poly(ether-amide) (PEA) as the polymer matrix was synthesized from reaction of 1,4-(4-carboxy phenoxy)butane (1) and bis(3-amino phenyl)phenyl phosphine oxide (2) via a direct polycondensation reaction. Nanoparticle and nanocomposite were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared. The effect of the presence of Fe₃O₄ nanoparticles on the thermal properties of PEA was studied using thermogravimetric analysis in nitrogen atmospheres. The magnetic properties of the sample were also investigated using an alternating gradient force magnetometer. We found that the Fe₃O₄ nanoparticles exhibit a ferromagnetic behaviour with a saturation magnetization of 59 emu/g and a coercivity of 104 Oe at room temperature. The coercivity of PEA/Fe₃O₄ nanocomposites is found to be 126 Oe, higher than 104 Oe which is obtained for Fe₃O₄.     

二氧化碳-氧化苯乙烯的共聚反应

由ＣＯ２－氧化苯乙烯（ＳｔＯ）配位催化共聚制得脂肪族聚碳酸苯亚乙酯,并用 ＩＲ、１ＨＮＭＲ和 ＤＳＣ等进行表征,用 ＴＧ对聚合物的热稳定性进行了分析。     

Ag-Fe复合氧化物催化剂的结构及还原性能

采用共沉淀法制备了ＡｇＦｅ复合氧化物催化剂．用ＸＲＤ研究了不同Ａｇ含量催化剂的结构变化情况,利用程序升温还原技术（ＴＰＲ）考察了热处理温度对催化剂还原性能的影响．结果表明：不同Ａｇ含量催化剂的还原能力与σＡｇＦｅＯ２晶相生成情况有对应关系,催化剂的氧活性主要来源于分散在其表面晶粒较小的σＡｇＦｅＯ２物种．     

光促进温和条件下烯烃与二氧化碳的羰基化反应

羰基化反应是有机合成化学中常用的方法之一,但常规的羰基化反应大多要求高温(150～200℃)、高压(10～20 M Pa)或使用贵金属催化剂(如钌、铑、铱等),并且C₁源多用一氧化碳^[1].开发和利用CO₂这一丰富的C₁资源,并最大限度地降低其排放量具有挑战意义.但CO₂活化比较困难,在通常条件下难以转化成其它化学品^[2].在光促进下的羰基化反应可克服上述困难,使反应在温和条件及非贵金属催化下完成,同时可用CO₂代替CO作为C₁源,因此这是一个对环境友好的工艺^[3].本文报道烯烃在光促进常温常压和非贵金属钴配合物催化下与二氧化碳的羰基化反应,同时通过¹³CO₂和¹³CH₃OH同位素实验,对反应产物的结构进行了分析.     

铁二亚胺配合物与水解乙基铝催化乙烯齐聚的研究

Ethylene oligomerization and polymerization catalyzed by α-diimine Pd(Ⅱ) or Ni(Ⅱ) complexes have been reported[1,2].     

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.     

Benzoylation of Toluene over Al-promoted SO_4~(2-)/M_xO_y(M=Zr,Ti,Fe) Catalysts

ＴｈｅｂｅｎｚｏｙｌａｔｉｏｎｏｆｔｏｌｕｅｎｅｗｉｔｈｂｅｎｚｏｙｌｃｈｌｏｒｉｄｅｉｓａｎｉｍｐｏｒｔａｎｔａｃｉｄｃａｔａｌｙｔｉｃＦｒｉｅｄａｌＣｒａｆｔｓｒｅａｃｔｉｏｎ．Ｌｅｗｉｓａｃｉｄｓ,ｓｕｃｈａｓｄｅｈｙｄｒａｔｅｄＡｌＣｌ３ａｎ...     

Copolymerization of Carbon Dioxide and Propylene Oxide with Zinc Catalysts Supported on Carboxyl-Containing Polymers

Polymer-supported zinc catalysts were prepared by the reaction of di-ethylzinc with polymers containing carboxyl groups. The catalysts were employed in the alternating copolymerization of carbon dioxide and propylene oxide to give poly(propylene carbonate) of high molecular weight. Copolymers of styrene and acrylic acid were shown to be better catalyst supports than poly(acrylic acid) and some other polymers. Maximum activity was achieved when the molar ratio of Zn/COOH was around unity. The yield and molecular weight of the polycarbonate rose with increasing reaction time. Higher reaction rates but lower molecular weights of the product were observed at elevated reaction temperatures     

Carbon Dioxide Reforming of Methane over Ni Catalysts Supported on Al2O3 Modified with La2O3, MgO, and CaO

The preparation of synthesis gas from carbon dioxide reforming of methane (CDR) has attracted increasing attention. The present review mainly focuses on CDR to produce synthesis gas over Ni/MO_x/Al₂O₃ (X = La, Mg, Ca) catalysts. From the examination of various supported nickel catalysts, the promotional effects of La₂O₃, MgO, and CaO have been found. The addition of promoters to Al₂O₃-supported nickel catalysts enhances the catalytic activity as well as stability. The catalytic performance is strongly dependent on the loading amount of promoters. For example, the highest CH₄ and CO₂ conversion were obtained when the ratios of metal M to Al were in the range of 0.04–0.06. In the case of Ni/La₂O₃/Al₂O₃ catalyst, the highest CH₄ conversion (96%) and CO₂ conversion (97%) was achieved with the catalyst (La/Al = 0.05 (atom/atom)). For Ni/CaO/Al₂O₃ catalyst, the catalyst with Ca/Al = 0.04 (atom/atom) exhibited the highest CH₄ conversion (91%) and CO₂ conversion (92%) among the catalysts with various CaO content. Also, Ni/MgO/Al₂O₃ catalyst with Mg/Al = 0.06 (atom/atom) showed the highest CH₄ conversion (89%) and CO₂ conversion (90%) among the catalysts with various Mg/Al ratios. Thus it is most likely that the optimal ratios of M to Al for the highest activities of the catalysts are related to the highly dispersed metal species. In addition, the improved catalytic performance of Al₂O₃-supported nickel catalysts promoted with metal oxides is due to the strong interaction between Ni and metal oxide, the stabilization of metal oxide on Al₂O₃ and the basic property of metal oxide to prevent carbon formation.     

还原条件对CO2加氢用Fe/TiO2催化剂结构的影响

 考察了5％Fe／TiO2催化剂在CO2加氢制低碳烃中的催化活性．最佳结果显示,CO2转化率为19．1％,C2＋烃选择性为50．1％．用X射线粉末衍射、激光拉曼光谱、穆斯堡尔谱及FeK－吸收边扩展X射线吸收精细结构等研究了该催化剂在还原条件下的体相及表面结构．结果表明,在Fe／TiO2中,主要存在超顺磁的Fe0,α－Fe,配位不饱和的Fe2＋物种及体相FeTiO3．还原温度对Fe／TiO2催化剂的体相和表面结构及催化性能有显著的影响．高温还原会破坏催化剂的表面结构,导致催化活性显著下降．将催化活性与体相及表面结构相关联,提出Fe0与配位不饱和的Fe2＋物种之间的协同作用是催化剂显示较高活性的重要原因．     

Metal (Fe, Co, Ni) Nanoparticles in Silica Gels: Preparation and Magnetic Properties

Metal containing silica gels with a Me/Si molar ratio between 0.01 and 0.2 are submitted to thermal treatment under hydrogen within the temperature range 600 to 1000°C. The changes occurring during these treatments are followed by X-ray diffraction, transmission electron microscopy, Mössbauer spectrometry and static magnetization measurements.During these treatments, nickel is nearly totally reduced to metal particles, the mean size of which increases from 3 to 10 nm with increasing temperature, but does not vary appreciably with nickel content. These particles exhibit a classical superparamagnetic behavior and are stable towards reoxidation when reexposed to air at room temperature.Iron and cobalt behave in a notably different manner. First, in both cases, silicates may be formed during the thermal treatment and consequently the reduction to the metallic state is not complete unless it occurs at high temperature (1000°C and above). Secondly, the particles formed are much less stable toward reoxidation, especially in the case of iron. Accordingly, the evolution of the magnetic behavior is much more complex than in the case of nickel.