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.     

Regeneration of C4H10 dry reforming catalyst by nonthermal plasma

Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons.An effort was made to regenerate the catalyst（Ni/7-alumina） by oxidation methods.Two approaches were carried out for the regeneration of the deactivated catalyst.The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300～500℃,while the second one only the thermal treatment in the same temperature range.The performance of the regenerated catalyst was evaluated in terms of C₄H₁₀ and CO₂ conversions and the physicochemical characteristics were examined using a surface area analyzer,an elemental analyzer,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt%after reforming C₄H₁₀ for 5 h at 540℃.The simple thermal treatment at 400℃reduced carbon content to 6.59 wt%whereas it was decreased to 3.25 wt%by the plasma and heat combination.The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃.As far as the catalytic activity is concerned,the fresh and regenerated catalysts exhibited similar C₄H₁₀ and CO₂ conversion efficiencies.     

ROLE OF MoO_3 AND La_2O_3 PROMOTERS IN Ni-CATALYZED METHANATION REACTIONS OF CO

A series of catalysts containing nickel were prepared by impregna-tion.The activity,heat resistance and sulfur resistance of catalysts were inves-tigated using catalytic microreactor.The experimental results show that the Ni/γ-Al_2O_3 catalysts containing molybdenum or lanthanum possess higher activity,better heat resistance and sulfur resistance than Ni/γ-Al_2O_3 catalyst.The sur-face behaviour of catalysts and the role of molybdenum or lanthanum in Ni-Mo-La/γ-Al_2O_3 system have been studied by XRD,TEM,XPS and TPY.It hasbeen shown that the addition of molybdenum or lanthanum can increase theconcentration of nickel atoms on the surface of catalysts,make the crystallinegranule of nickel smaller,increase the number of active centers of nickel andaffect the electronic structure of nickel.All these avtions will improve thecatalytic activity and surface behaviour of catalllysts.     

CO2 reforming of methane over nickel catalysts supported on nanocrystalline MgAl2O4 with high surface area

In this paper dry reforming of methane (DRM) was carried out over nanocrystalline MgAl2O4-supported Ni catalysts with various Ni loadings. Nanocrystalline MgAl2O4 spinel with high specific surface area was synthesized by a co-precipitation method with the addition of pluronic P123 triblock copolymer as surfactant, and employed as catalyst support. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption, H2 chemisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), temperature- programmed desorption (TPD) and transmission and scanning electron microscopies (TEM, SEM) techniques. The obtained results showed that the catalyst support has a nanocrystalline structure (crystal size: about 5 nm) with a high specific surface area (175 m2 g-1) and a mesoporous structure. Increasing in nickel content decreased the specific surface area and nickel dispersion. The prepared catalysts showed high catalytic activity and stability during the reaction. SEM analysis revealed that whisker type carbon deposited over the spent catalysts and increasing in nickel loading increased the amount of deposited carbon. The nickel catalyst with 7 wt% of nickel showed the highest catalytic activity.     

Ni/MgO catalyst prepared using atmospheric high-frequency discharge plasma for CO2 reforming of methane

A new type of Ni/MgO catalyst was prepared using atmospheric high-frequency discharge cold plasma. The influences of conventional method, plasma method, and plasma plus calcination method on the catalytic activity were studied and the CO2 reforming of methane was chosen as the probe reaction. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy, and CO2 temperature-programmed surface reaction techniques. The results suggested that the nickel-based catalyst prepared by plasma plus calcination method possessed a smaller particle size and a higher dispersion of active component, better low-temperature activity and enhanced anti-coking ability. The conversion of CO2 and CH4 was 90.70% and 89.37%, respectively, and the reaction lasted for 36 h without obvious deactivation under 101.325 kPa and 750°C with CO2/CH4 = 1/1.     

Ni-Co/Mg-Al catalyst derived from hydrotalcite-like compound prepared by plasma for dry reforming of methane

Ni-Co bimetallic catalysts with different Ni/Co content were derived from cold plasma jet decomposition and reduction of hydrotalcite-like compounds containing Ni,Co,Mg and Al,and their catalytic performance was investigated with dry reforming of methane.Experimental results showed that the hydrotalcite-like precursors could be completely decomposed and partly reduced by cold plasma jet,and the Nicontained catalysts exhibited much higher activity than the catalyst without Ni.Especially,the catalyst with Ni/Co ratio of 8/2 achieved not only the highest conversions of 80.3%and 69.3%for CH4 and CO2,respectively,but also the best stability in 100 h testing.The catalysts were characterized by XRD,XPS,TEM and N2 adsorption techniques,and the results showed that the better performance of the 8Ni2Co bimetallic catalyst was attributed to its higher metal dispersion,smaller metal particle size,as well as the interaction effect between Ni and Co,which were brought by the special catalyst preparation method.     

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.     

Preparation of Metal Particle Catalysts Wrapped in Organosilicon Compound via Metal Vapor Synthesis

Three kinds of metal catalysts Ni/D_4, Ni-Mn/D_4, Ni-Mn-La/D_4, wrapped in organosilicon compound were prepared by metal vapor synthesis. Their feature was characterized with XRD, TEM, XPS, FMR and static magnetic measurement. The metal particle size in catalysts was less than 3.5 am. The results of XPS showed that the metals in the catalysts existed in zero and other valent state. Inner metal, as an organosilicon compound folded around the metal particle, was protected from oxidation. FMR and static magnetic measuremeat revealed that metal particles were spheroidal and of superparamagnetism. Of all the caralysts the catalytic activity of Ni-Mn-La/D_4 was the highest in hydrogenating furfuraldehyde into furfuralcohol.     

Effects of Citric Acid Concentration and Activation Temperature on the Synthesis of Carbon Nanotubes

A series of Ni-La-Mg catalyst samples were prepared by citric acid complex method, and carbonnanotubes were synthesized by catalytic decomposition of CH4 on these catalysts. The effects of the citricacid concentration and the activation temperature on catalytic activity were investigated by CO adsorption,TEM and XRD techniques. The experimental results showed that the particle size of the catalysts preparedthrough gel auto-combustion varied with the concentration of citric acid. Therefore carbon nanotubes with different diameters were obtained correspondingly. The effect of activation temperature on the activity of catalyst was negligible from 500 to 700℃, but it became pronounced at lower or higher temperatures.     

PROPERTIES OF HIGHLY DISPERSED PALLADIUM CATALYSTS ON POLY N-VINYL-2-PYRROLIDONE

Four kinds of palladium catalysts dispersed on poly-N-vinyl-2-pyrrolidone were prepared by using CH3OH-NaOH, NaBH4, H2O or CH3OH-H2O as the reducing agent in the process of catalyst preparation. The catalysts were characterized by XPS, TEM, XRD and used for the hydrogenation of methyl acrylate. It was found that the valence state of palladium and distribution of palladium particles as well as the hydrogenation rate were greatly affected by the reducing agent. The best evenly dispersed palladium catalyst showing high hydrogenation activity was prepared using CH3OH-NaOH as the reducing agent.     

Electrodeposition of mesoporous semimetal and magnetic metal films from lyotropic liquid crystalline phases

Mesoporous semimetal bismuth film and magnetic metal nickel and cobalt thin films have been electrodeposited from hexagonal or lamellar structured lyotropic liquid crystalline phases with polyoxyethylene surfactant. The liquid crystalline templates are characterized by low-angle X-ray diffraction (XRD) and polarized-light optical microscopy (POM). The metal films are characterized by low-angle and wide-angle XRD, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The magnetic measurements on the mesoporous nickel and cobalt films are shown to have higher coercivity (Hc) than the nonporous polycrystalline films.     

CdS纳米棒的制备、表征及其形成机理

以三辛基膦(TOP)为单一配位溶剂,二水合乙酸镉和硫粉为前驱体,用高温热解的方法制备CdS纳米棒.通过X射线衍射(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)、紫外-可见(UV-Vis)分光光度计、荧光(PL)光谱、傅里叶变换红外(FTIR)光谱和核磁共振磷谱(31PNMR)等方法对样品的结构、形貌和光学特性进行了表征.考察了前驱体Cd/S摩尔比和反应物浓度对硫化镉纳米结构的影响.实验结果表明,该法制备的CdS纳米棒为纤锌矿结构,直径为4.0nm,长度为28.0nm,沿[001]方向择优生长,具有量子限域效应.同时,对CdS纳米晶的形成机理进行了初步的探讨.     

Preparation and Characterization of NiO Nanoparticles Via Solid-State Thermal Decomposition of Nickel(II) Schiff Base Complexes [Ni(salophen)] and [Ni(Me-salophen)]

This study focuses on the preparation and characterization of nickel oxide nanoparticles from nickel(II) Schiff base complexes as new precursors. At first nickel(II) complexes [Ni(salophen)] and [Ni(Me-salophen)] were synthesized and characterized by elemental analyses and FT-IR spectroscopy. Then NiO nanoparticles were prepared by solid-state thermal decomposition at 550 ºC for 3.5 h. The FT-IR spectrum confirmed the composition of products. The crystalline structures and morphology of products were studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results revealed that the obtained products were nickel oxide. SEM and TEM images demonstrated that the NiO nanoparticles have uniform shape with size between 35 and 70 nm.     

Synthesis of Nickel Sulfide Particles by Solvothermal Process

Pyrite nickel disulfide and millerite nickel monosulfide have been successfully prepared by solvothermal method based on the reaction of Ni(NO3)26H2O and H2NC(S)NH2 in benzene and ethylenediamine (EDA). The final products were characterized by X-ray powder diffraction(XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The effects of the solvent, reaction temperature and time on the morphology and phase of the products have been discussed.     

一种新型的空心镍纳米球的合成

通过以二氧化硅粒子作为模板和金纳米粒子为表面晶种的方法制备了壳厚度可控的镍空心球。采用TEM﹑XRD对二氧化硅/镍复合球和镍空心球进行了表征和研究。结果表明镍纳米壳是由似针状的面心立方的镍纳米粒子构成的，碱溶液处理过程不影响镍纳米壳的形貌。高温处理显示镍空心球具有良好的热稳定性。     

铂纳米空球的制备及其对甲醇氧化的电催化性能

以粒径为100nm的硒球作模板,在室温下批量合成了粒径约110nm、壳厚约5 nm的铂空球.采用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HR-TEM）、选区电子衍射（SAED）、X射线衍射（XRD）、能量色散X射线谱（EDX）等检测技术表征了其形貌与结构;以甲醇为探针分子研究了铂纳米空球修饰玻碳电极对甲醇电氧化的催化性能.结果表明,由铂原子簇团构筑的多孔铂空球粒径均匀、分散性好、结构稳定、比表面积大、传质性能好,是甲醇氧化的理想催化材料.循环伏安（CV）结果表明:当甲醇氧化的电流密度0.10 mA·cm^-2,正扫时,铂纳米空球的氧化电位与实心铂纳米粒子及铂黑相比,分别负移了约110和64mV;负扫时,前者比后两者分别负移了约51与13 mV.经800圈循环伏安扫描后,正扫时,甲醇在铂纳米空球上氧化峰的电流密度为实心铂纳米粒子及铂黑上的13和15倍;负扫时,前者为后两者的19和38倍.表明铂纳米空球对甲醇氧化具有较好的催化活性和稳定性.     

Gold-Nickel Hydroxide Multi-Layers with Selective Absorption in the Visible Range

This work reports the growth of layered nickel hydroxide/gold films by sol-gel and dip-coating methods to obtain colored films for applications in switchable optical devices. The nickel and gold-based films were deposited on mica and glass plates from alcoholic sols. The distribution of electron density inhomogeneities (voids, nickel and gold particles) in the films was determined by means of small angle X-ray scattering (SAXS). The SAXS measurements were used to determine the nickel and gold particle sizes and to give guidelines to the appropriate chemical route to deposit homogeneous colored films. X-ray diffraction (XRD) was used to monitor the crystalline properties. Transmission electron microscopy (TEM) was used to observe the nanostructure of the gold particles and atomic force microscopy (AFM) to analyze the film surface. Spectral transmission was used to investigate the optical properties in these different layered systems, which present an absorption band in the visible region due to the gold aggregates. The composite material is deep blue. The analyses of SAXS data, TEM and AFM pictures are consistent, i.e., the formed Au particles are polydisperse in size and their clustering depends on the NiO _x H _y layer. The Au particles are polycrystalline, with [111]-preferred orientation, as determined by XRD. The nickel oxy-hydroxide matrix is amorphous.     

磁性金属镍纳米管的有效合成

以多孔氧化铝为模板, 三嵌段共聚物F127(EO108PO69EO108, EO: ethylene oxide, PO: propylene oxide)为添加剂, 采用电化学沉积技术, 制备了高度有序的磁性金属镍纳米管阵列. 该合成方法简单、有效、易操作, 特别是, 氧化铝模板的孔壁不需要进行任何修饰. 通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)和振动样品磁强计(VSM)对产物的形貌、结构和磁学性质进行表征. X射线衍射(XRD)分析表明, 产物的晶型结构为面心立方. 利用透射电子显微镜研究了实验参数, 如电流密度、共聚物浓度和电沉积时间, 对产物形貌的影响, 结果表明, 镍纳米管的管壁厚度随着电流密度增大和电沉积时间的延长而变大, 但几乎不受F127浓度变化的影响. 以上的实验表明, 调节实验参数, 可以有效控制纳米管管壁的厚度. 磁性研究结果表明, 与块体镍相比较, 镍纳米管阵列表现出较大的矫顽力.     

Ni(OH)2纳米管的制备、表征及电化学性能

以多孔氧化铝为模板, 在不同溶液浓度下, 用化学沉积法制备了氢氧化镍纳米管. 采用XRD, SEM, TEM和HRTEM等手段, 对产物的物相、表面形貌及微结构进行了表征. 结果表明所得产物是高纯度的氢氧化镍纳米管, 外径约为180～220 nm, 管壁厚20～30 nm. 将所制备的氢氧化镍纳米管制成电极, 其电化学性能测试表明, Ni(OH)₂纳米管的中空结构特点, 能够有效地提高镍电极的充电效率、放电比容量、高倍率及高温放电性能. 机理分析表明中空结构的Ni(OH)₂纳米管对于提高碱性二次电池的综合性能有着极为重要的意义.     

Partial oxidation of methane to syngas catalyzed by a nickel nanowire catalyst

A nickel nanowire catalyst was prepared by a hard template method,and characterized by transmission electron microscopy (TEM),N2 physical adsorption,X-ray photoelectron spectrometry (XPS),X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR).The catalytic properties of the nanowire catalyst in the partial oxidation of methane to syngas were compared with a metallic Ni catalyst which was prepared with nickel sponge.The characterization results showed that the nickel nanowire catalyst had high specific surface area and there was more NiO phase in the nickel nanowire catalyst than in the metallic Ni catalyst.The reaction results showed that the nickel nanowire catalyst had high CH4 conversion and selectivities for H2 and CO under low space velocity.