The preparation of high surface area nickel oxide electrodes for synthesis

A study of the electrodeposition of nickel onto copper and graphite is described; the objective was to prepare high surface area, i.e. microrough, but stable deposits which could be used as nickel oxide anodes in aqueous base. It is shown that such electrodes may be prepared by electrodeposition at a high current density (200 mA cm^–2) from a Watts bath and that they give useful apparent current densities for a model synthetic reaction, the oxidation of ethanol to acetic acid.     

Interactions of supported nickel and nickel oxide catalysts with methane and steam at high temperatures

The catalytic performance of cermets made of 10% nickel or nickel oxide supported on YSZ (yttria-stabilized zirconia) for chemical looping combustion (CLC) and steam reforming (SR) of methane at 700 °C is investigated. Steam reforming of methane over the reduced catalyst resulted in a syngas containing more than 70% hydrogen and about 15% carbon monoxide. Chemical looping combustion of methane with insufficient lattice oxygen could potentially lead to 40–65% hydrogen rich gas products. Prolonged induction period (e.g. 30–80 min) in reduction of nickel oxide by methane has been observed in the presence of steam. The span of induction period increases by increasing steam partial pressure. It is hypothesized that the delayed reduction of nickel oxide is related to the retarding effect of steam on autocatalytic reactions of methane and hydrogen with lattice oxygen of nickel oxide and the subsequent reforming reactions.     

负载型磷化镍催化剂的制备及其催化应用

综述了近年来负载型磷化镍催化剂在制备方法(还原法、热解法和溶剂热法)、活性组分和载体改性及其催化应用方面的研究进展,并对比了各种制备方法的优缺点,其中还原法流程简单,但所用温度较高,时间较长;热解法所需温度较低,制备过程简单,但易于生成副产物水;而溶剂热法具有所需温度低,物相形成过程易控制等优点。负载型磷化镍催化剂由于其良好的加氢氢解及烷烃临氢异构化等反应性能,是一类更加廉价的新型催化剂,具有很好的发展前景。     

Reductibility of silica supported nickel oxide

The reduction of nickel/silica catalysts was studied in parallel by temperature programmed reduction (TPR) and X-ray diffraction (XRD) methods. The calcined materials contain nickel in the form of nickel oxide and nickel hydrosilicates and a part of the oxide particles is covered with the hydrosilicate species. This oxide is reduced in the same way as unsupported nickel oxide in the absence of water, and in a similar way to nickel hydrosilicates in the presence of water.     

Vinyl polymerization of norbornene over supported nickel catalyst

A series of nickel complexes, bis(salicylideneiminato)nickel(II), were supported on spherical MgCl₂ and SiO₂. Scanning electron microscopy, energy‐dispersed X‐ray spectroscopy, and the BET method for surface areas measurements were utilized to examine the supporting process of the catalysts. The particle morphology of the original support is retained and replicated throughout the supported catalyst preparation and norbornene polymerization. Spherical polymer particle morphology was achieved, without reactor fouling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2233–2240, 2006     

Thiophene Poisoning and reactivation of a supported nickel hydrogenation catalyst: The effect of temperature

The extent and type of poisoning of an 8 wt% Ni/γ-Al₂O₃ catalyst by thiophene has been examined in ethylbenzene hydrogenation reaction, between 403 and 523 K. The results suggest that at the higher temperatures the deactivation can take place through two different mechanisms. In one case, the formation of ‘Ni-S’ surface species on the more active sites at the beginning of the reaction, produces a slow and irreversible poisoning. In the other, the planar adsorption of thiophene on the other sites produces a fast and reversible deactivation. At lower temperatures, the second mechanism seems to be predominant due to the fact that the hydrogenolysis activity diminishes.     

Gas phase catalytic hydrodechlorination of chlorophenols using a supported nickel catalyst

The gas phase hydrodechlorination of single component and mixtures of o-, m- and p-chlorophenol was studied over the temperature range 423 K≤T≤573 K using a 1.5% (w/w) Ni/SiO₂ catalyst. The variation of catalyst activity with time-on-stream for each isomer is illustrated and the role of reaction temperature and thermodynamic limitations are addressed. The catalyst exhibits both short term and irreversible long term deactivation which is accounted for in terms of competitive adsorption and electronic effects. The hydrogen treatment of both phenol and chlorobenzene under the same reaction conditions are also considered for comparative purposes. The presence of the hydroxyl function enhances the rate of hydrodechlorination via an inductive effect. The relationship between rate and isomer structure is discussed on the basis of reactant adsorption where steric hindrance, in the case of the ortho-form, appreciably restricts dechlorination to such an extent that o-chlorophenol remains unreacted in equimolar o-/p- and o-/m-chlorophenol mixtures. Catalytic hydrodechlorination is viewed as a non-destructive low energy methodology for handling concentrated chlorine gas streams and relationships that describe the dependence of dechlorination rate on chlorine concentration are provided and can be used to evaluate the productive lifetime of the catalyst.     

羰基镍粉焙烧制备高纯度微米氧化亚镍粉体的研究

以羰基镍粉为原料,采用焙烧法制备了氧化亚镍,并将其球磨后得到微米粉体。采用热重-差示扫描量热仪（TG-DSC）研究了羰基镍粉在空气气氛中加热时的氧化行为,利用激光粒度分析仪、等离子体光谱仪、X射线衍射仪（XRD）和扫描电镜（SEM）等分析了样品结构、成分和形貌。结果表明：空气和氧气两种气氛对产物纯度影响不明显。在两种载气条件下,通过优化焙烧温度和焙烧时间（焙烧温度为700 ℃、焙烧时间为2 h、载气流量为1.5 L/min）,羰基镍粉可直接焙烧制备得到纯度为100%、结晶度高的面心立方体氧化亚镍,球磨后得到粒度为4~19 μm的类球形微米氧化亚镍粉末。制备过程具有工艺简单、环境友好的特点。     

载体改性对负载氧化铜催化剂催化性能的影响

采用分步浸渍法制备了系列CeO2、ZrO2等氧化物改性TiO2载体,并负载了氧化铜催化剂,并对其乙酸乙酯催化燃烧活性进行了评价,对催化剂进行了表征。结果表明CeO2-ZrO2复合氧化物的添加有效提高了CuO在TiO2载体表面的分散度,明显提高了催化剂活性,并且有效抑制了反应过程中乙醛、乙醇等副产物的生成。负载CuO催化剂上乙酸乙酯可在约280℃达到完全转化,完全转化时CO2的选择性达到100%,反应过程中乙醛副产物的最大摩尔生成量不超过5%。     

Ethylene dimerization catalyst of nickel sulfate supported on silica-alumina

Catalysts containing various nickel sulfate content were prepared by dry impregnation of silica-alumina or silicagel with aqueous solution of nickel sulfate. SiO₂-Al₂O₃ alone without NiSO₄ was totally inactive for the ethylene dimerization reaction at room temperature. However, NiSO₄/SiO₂-Al₂O₃ was found to be very active even at room temperature compared with NiSO₄/SiO₂.     

Nickel catalyst supported on magnesium oxide with high surface area and plate-like shape: A highly stable and active catalyst in methane reforming with carbon dioxide

Nanocrystalline magnesium oxide with a high surface area and a highly defective surface structure with plate-like shape was synthesized by a facile method using polyvinyl alcohol as a surfactant. The prepared MgO was employed as support for nickel catalysts with various nickel loadings in methane reforming with carbon dioxide. The results showed high catalytic activity and stability for the prepared catalysts due to the formation of NiO–MgO solid solution and high basicity of support. The 5% Ni/MgO catalyst was very effective in this process and exhibited stable catalytic performance for 50 h of reaction as well as a high resistance against carbon formation.     

Effect of preparation method on the structure and catalytic property of activated carbon supported nickel oxide catalysts

A series of activated carbon (AC) supported nickel oxide (NiO) catalysts were prepared by aqueous reduction preparation methods with nickel nitrate as a precursor. The effects of preparation procedure and reducing agent on catalyst structure and catalytic property were investigated. Based on the information obtained from physico-chemical characterizations and sorbitol dehydration performances, preparation methods were found to have a significant influence on NiO distribution and surface acidity. The catalysts prepared through the simultaneous loading-reduction procedure had stronger acidity and higher NiO dispersion on the outer surface of AC, which contributed jointly to high sorbitol conversion (turn-over frequency of 190–240 h^?1) and slightly low selectivity to anhydro sugar alcohols (ca. 66%). Correspondingly, with the procedure of reduction of supported nickel catalyst precursors, the selectivity to anhydro sugar alcohols was improved by ca. 10%, while sorbitol conversion was quite low (ca. 20%). Reducing agent exerted less influence on the structure compared with preparation procedure. However, when the simultaneous loading-reduction procedure was used, sodium borohydride influenced the acidity remarkably by formation of a new strong acid site, resulting in better dehydration performances.     

镍系催化丁二烯聚合催化剂制备工艺的改进

采用超声波对催化剂进行处理改善了催化剂的分散性，配合添加微量水调节聚合反应的诱导期和体系的稳定性，拓宽了Al/B对相对分子质量的调节范围，单体转化率大于80％的条件下，制得了门尼黏度大于80的高相对分子质量基础顺丁橡胶。     

The preparation of a high surface area metal oxide prepared by a matrix-assisted method for hot gas desulphurization

Metal oxide sorbents with high surface area for ultra hot gas cleanup were prepared by a matrix-assisted method. A granular type of activated carbon was used as a matrix in order to increase the surface area of the metal oxide. Zinc was loaded on the surface of activated carbon by an impregnation method. Metal oxide maintained in the form of a matrix structure was observed by scanning electron microscope (SEM). A Wurtzite structure of ZnO was also confirmed by XRD measurement of the prepared granular particles. Particle sizes of metal oxide were distributed in the range of 5-50 nm in transmission electron microscope (TEM) images. The surface area of the zinc oxide calcined at 500 °C was around 56 m²/g. The values of the particle size and the surface area were directly related to the temperatures of calcination. The curves of sulphidation rates for the zinc oxides with high surface areas were measured by a Cahn balance at several different calcination temperatures. It was found that a catalyst with a large surface area showed a high activity in the desulphurization. Not only sulphur content in a simulated coal gas was completely removed by the ZnO with high surface area but also COS formed by a secondary reaction was not detected in the sulphidation tests performed in a fixed-bed reactor system. It was believed that the high surface area ZnO prepared in this study is a suitable sorbent for the ultra hot gas cleaning from the experimental results.     

介孔氧化镍应用与制备进展

介绍了介孔氧化镍的结构与特点,阐述了介孔氧化镍在敏感材料、催化剂和电化学领域的应用.介绍了介孔氧化镍的主要制备方法直接热解法与模板法,其中直接热解法是介孔氧化镍最简便的制备方法,但该法难以制备得到特定形貌的介孔氧化镍,只能用于催化及敏感等领域.模板法能够得到特定形貌的介孔氧化镍,但实际收率不高,且在制备过程中易引入些杂质.开发易操作、设备易实现的模板法生产工艺是未来制备介孔氧化镍的主要方向.     

Vapor-Phase hydrogenation of methyl oleate in the presence of a supported nickel catalyst

The reaction order with respect-to hydrogen was found to be higher than unity and increased with increasing temperature in the vapor-phase hydrogenation of methyl oleate in the presence of a supported nickel catalyst. These findings may be of certain interest in understanding the role that hydrogen plays in fat hydrogenation selectivity. Two reaction mechanisms were discussed to explain the high reaction order. The two reaction models were shown to give the same rate equation.     

镍基海泡石催化剂制备方法与表面性质的研究

本文研究了不同的制备方法对镍基海泡石催化剂苯加氢活性的影响并用TPR、Ｈ２-ＴＰＤ、ＸＲＤ、ＸＰＳ、ＴＥＭ等方法表征了催化剂的表面性质。结果表明,焙烧温度及浸渍方式对催化剂活性的影响较大,其中以先浸Ｓｍ后浸Nｉ并在573K焙烧5ｈ所制得的催化剂效果最佳。海泡石及钐能提高镍的分散度,增加活性镍的比表面,同时具有给电子作用,使镍的电子云密度升高。     

负载型NiMo加氢处理催化剂氧化物载体研究进展

以NiMo在加氢精制中的应用为线索,按催化剂载体的不同,简介了以单一氧化物和复合氧化物为载体的催化剂的制备方法,总结了NiMo为活性组分,氧化物为载体的加氢精制催化剂的应用进展。按照载体的不同,从单一氧化物载体Al_2O_3,TiO_2和SiO_2,以及复合氧化物载体角度总结了催化剂在加氢精制中的应用。氧化物载体具有热稳定性好,酸碱性适宜的特点,一直是人们研究的重要内容。     

负载型NiMo加氢处理催化剂氧化物载体研究进展

以NiMo在加氢精制中的应用为线索,按催化剂载体的不同,简介了以单一氧化物和复合氧化物为载体的催化剂的制备方法,总结了NiMo为活性组分,氧化物为载体的加氢精制催化剂的应用进展。按照载体的不同,从单一氧化物载体Al_2O_3,TiO_2和SiO_2,以及复合氧化物载体角度总结了催化剂在加氢精制中的应用。氧化物载体具有热稳定性好,酸碱性适宜的特点,一直是人们研究的重要内容。     

负载型骨架镍催化剂催化轻质石脑油加氢脱苯

针对当前对溶剂油中苯含量的严格要求,研究负载型骨架镍催化剂在轻质石脑油加氢脱苯反应过程中的加氢性能,并考察反应温度、反应压力、空速以及氢油体积比等对轻质石脑油加氢脱苯反应的影响。结果表明,骨架镍催化剂具有较高的低温加氢活性,适宜条件为:反应温度140℃,反应压力0.2 MPa,空速2 h~(-1),氢油体积比120,此条件下,苯转化率达到99%。