碳笼负载镍基磁性催化剂Ni@Cage-C的制备与性能研究

以自然结晶法制备的ZIF-67为前驱体,采用包裹-刻蚀-碳化策略,得到大小均匀的纳米碳笼（Cage-C）,再于液相条件下以碳笼为载体负载上活性金属镍（Ni）,成功制备了非贵金属磁性催化剂Ni@Cage-C,并应用于对硝基苯酚催化还原反应以考察其多相催化性能。结果表明：优化条件下制备的Ni@Cage-C催化剂为碳笼包裹单质镍结构,其平均颗粒大小为550 nm;将Ni@Cage-C用于对硝基苯酚催化还原反应时,催化性能明显优于参照催化剂雷尼镍（Raney-Ni）。质量反应速率常数kM为6.11 mg-1·min-1,催化效率达到98.87%,循环反应十圈后活性仍高于初始活性的85%。     

高温自生压法制备碳纳米管和碳纳米胶囊

以四氢萘和四水合乙酸镍的混合物作为前驱体,采用高温自生压催化热解法在不同温度下制备碳纳米管、碳纳米胶囊。通过SEM、TEM、XRD和VSM对产物进行了表征测试。结果表明,随着反应温度的上升,产物中碳纳米管数量呈递增趋势。从800℃到1 000℃,碳纳米管的平均直径逐渐减小。催化剂的去活化作用导致了碳纳米胶囊结构的形成。     

溶胶-凝胶法制备的SiO2催化生长单壁碳纳米管

溶胶-凝胶法是制备纳米粒子的一种重要方法。采用高化学活性的化合物作反应前驱体经溶胶、凝胶过程,再经热处理而生成颗粒较均一的纳米粒子。分别在酸催化和碱催化条件下以原硅酸四乙酯（TEOS）为前躯体制备出SiO2纳米颗粒,用于生长单壁碳纳米管。最后发现,此SiO2粒子作为一种非金属催化剂,其催化生长的碳纳米管密度和结构均一而且产物中无残留催化剂颗粒,扩大了碳纳米管的性能及应用。     

微波辅助合成纳米氧化铜

以醋酸铜为前驱体,在微波作用下制备纳米氧化铜。借助透射电镜（TEM）、X-射线衍射（XRD）等手段对微波合成的氧化铜进行了表征。实验结果表明：采用该法可以制分散良好的纳米氧化铜;分散剂通过表面修饰抑制颗粒的团聚;微波加热促进了前驱体的转化,并抑制颗粒的长大。微波加热是合成纳米氧化铜粒子的一种快速、有效的方法;不同溶剂、配体对纳米氧化铜的形貌有较大影响;PVP的加入能起到稳定、分散纳米氧化铜粒子的作用。     

超分子水凝胶原位制备纳米镍及其在对硝基苯酚催化还原中的应用

在超分子水凝胶中负载Ni²⁺,再添加NaBH₄原位还原制备得到纳米镍。利用EDS、SEM、TEM及流变等方法对复合催化剂进行结构和性能表征,结果发现纳米镍尺寸约为5～10 nm,均匀分散于水凝胶中,复合催化剂具有良好的自修复能力。利用UV-Vis研究了其在催化还原4-NP中的性能,通过对反应随时间的变化及在不同温度下的催化性能研究发现,该反应动力学数据符合一级反应特征,表观速率常数与反应温度呈线性关系,催化剂重复使用6次后仍然保持了良好的催化性能。     

高镍多元前驱体的制备与研究

本文高镍前驱体采用控制结晶法制备,研究了控制结晶法与高镍前驱体的物理性能及微观结构之间的关系,分析了各个主要因素对高镍前驱体制备的影响。找到影响高镍前驱体制备的因素依次是氨水浓度、p H值、反应温度、固含量、反应时间、成分含量、杂质、反应气氛。通过分析讨论找到了最佳工艺条件,并成功制备样品,研究了高镍前驱体在最佳工艺条件制备得到高镍正极材料,通过XRD物相分析单一物相,层状结构完整,微晶结构均匀而清晰。     

DNA辅助合成Pd纳米粒子及其催化性能研究

采用鱼精DNA为模板,利用Pd2+离子与鱼精DNA间的配位作用将其预先结合在DNA模板上,再以原位还原的方法制备水相中稳定、分散的钯(Pd)纳米粒子。用透射电子显微镜(TEM)对Pd纳米粒子的形貌进行表征。以Pd纳米粒子催化4-硝基苯酚还原为4-氨基苯酚的实验来考察Pd纳米粒子的催化性能,实验结果发现鱼精DNA辅助合成的Pd纳米粒子有较好的催化性能。     

原位溶胶-凝胶法改性EPDM及其表征

采用原位溶胶-凝胶反应制备乙丙橡胶/ SiO₂纳米复合材料。分别以乙丙橡胶（EPDM）和γ-甲基丙烯酰氧丙基三甲氧基硅烷（KH570）接枝改性的乙丙橡胶 （EPDM-g-KH570）在前驱体四乙氧基硅烷 （TEOS）中溶胀,再浸入含有正丁胺的催化剂溶液中催化前驱体的原位溶胶-凝胶反应。考察了不同溶剂以及催化剂含量对TEOS转化率和原位生成的SiO₂粒径的影响。采用FT-IR、SEM等测试手段对纳米复合材料进行了表征。结果表明,接枝KH570后,TEOS转化率明显提高,SiO₂粒径明显减小,在材料中的分散性很好。     

N-掺杂碳材料负载钯纳米催化剂的制备及其催化活性应用研究

研究了以3-MBP-dca(3-甲基-1-丁基吡啶二氰胺)离子溶液做前体,用煅烧法合成负载在SiO2颗粒表面的N-掺杂碳材料,在超声条件下,以汉斯酯作为还原剂将二价钯离子通过原位还原为钯纳米粒子并负载到制备的碳材料上,通过XRD、XPS及HRTEM等方法进行表征。以苄醇选择性催化氧化为苯甲醛为模型反应,研究纳米催化剂的催化活性,实验结果表明,该催化剂对苄醇的氧化反应有良好的催化活性,且对带有不同供电子基团的反应底物都有较好的适用性。     

功能化层状硅酸镍在磁、电及催化领域的应用

二维纳米材料层状硅酸镍（Ni-PS）具有片层结构规则有序、比表面积高和层间性能可调等优点,作为功能材料在磁、电及催化等领域具有广泛的应用前景。本文在综述了Ni-PS的合成机理和制备方法的基础上,介绍了引入有机Si源、利用金属离子（或氧化物）进行掺杂、合成纳米管以及与碳基材料进行复合等手段来调控Ni-PS的结构和性能,详细阐述了Ni-PS或作为前体在制备高质量金属纳米粒子、电极材料、磁性载体和重金属离子吸附剂等方面的应用,着重指出Ni-PS的独特层状结构能够在还原过程中限制金属扩散和保护纳米粒子不被氧化和烧结长大,可用于制备新型高效Ni基催化剂,被广泛应用于制合成气、催化制氢/加氢及分子链催化重构等。最后,提出了Ni-PS在材料领域的发展方向和建议：深入研究Ni-PS的合成技术和改性方法,制备高性能、多功能Ni-PS及复合材料,进一步拓展其在功能材料和工程材料领域的应用。     

非晶态Ni-B合金在催化苯丙酮酸胺化加氢反应中活性寿命的研究

通过化学还原法制备了非晶态Ni-B合金催化剂,考察了催化剂在苯丙酮酸胺化加氢制备苯丙氨酸反应中的活性寿命。结果表明,非晶态Ni-B合金催化剂表现出比传统催化剂如雷尼镍和漆原镍等更为优异的活性与寿命。Ni-B合金催化剂经过简单的过滤回收步骤,重复使用5次后,催化活性没有明显大幅度下降,而雷尼镍和漆原镍分别循环使用3次和2次后,催化活性显著降低。结合XRD、DSC和TEM等手段,针对新鲜和使用回收后的催化剂进行了表征,发现非晶态结构在苯丙酮酸加氢反应环境中没有出现明显晶化现象,而小尺寸纳米颗粒的团聚和部分镍的氧化可能是导致催化剂活性降低的主要原因     

Synthesis of magnetically separable ordered mesoporous carbons from F127/[Ni(H2O)6](NO3)2/resorcinol-formaldehyde composites

An easy method is described for the synthesis of a mesostructured Ni/ordered mesoporous carbon (OMC) composite with a highly ordered cubic structure (space group Im3m). This synthesis was carried out by the carbonization of the F127/[Ni(H₂O)₆](NO₃)₂/RF (resorcinol-formaldehyde) composite self-assembled in an alkaline medium. The effects of nickel loading content and carbonization temperature on the morphologies, pore features, structures and magnetic properties of these Ni/OMC composites were investigated using the thermogravimetric analysis, X-ray diffraction, nitrogen sorption, transmission electron microscopy and vibrating-sample magnetometer measurements. It was found that Ni²⁺ was captured by the network of F127/RF and further reduced into metallic Ni nanoparticles during the carbonization. The nickel nanoparticles were well-dispersed in the ordered mesoporous carbon walls. The Ni/OMC composites exhibit the soft ferromagnetic behavior and the magnetization parameters can be adjusted by the content of nickel and the carbonization temperatures. The excellent acid-resistant property of the magnetic materials makes them useful in magnetic separation.     

Carbon nanotubes filled with metallic nanowires

A facile method is proposed to use LaNi₂ hydrogen storage alloy as a catalyst precursor to produce metallic nickel filled carbon nanotubes. Multi-walled carbon nanotubes filled with long continuous nickel nanowire with several microns in length are synthesized through chemical vapor deposition at low temperature (550 °C). It is more efficient to fill Ni nanowires into nanotubes after the oxidation treatment of LaNi₂ alloy at low temperatures, while the oxidation treatment at high temperature results in the forming of herringbone carbon nanofibers with tips of Ni nanoparticles. The metallic Ni nanowires inside the cores of carbon nanotubes could not be eliminated during the purification process in concentrated hydrochloric acid. The analysis of transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) reveals that the metallic nickel nanowires filled inside carbon nanotubes exist as a single crystalline with fcc structure.     

Carbon nanotube growth at 420 °C using nickel/carbon composite thin films as catalyst supports

Nickel/carbon composite (Ni/C) thin films were used as catalyst supports for the growth of vertically aligned multiwalled carbon nanotubes (MWCNTs) at temperature as low as 420 °C. Nickel nanoparticles embedded within the carbon matrix of Ni/C films have served as catalysts for the synthesis of nanotubes by PECVD using acetylene/ammonia plasma. Two different nickel contents (40 at.% and 60 at.%) in the films were used. Analysis indicated a diffusion of nickel atoms in the form of nanoparticles to the film surface upon annealing. This diffusion depends on both annealing temperature and nickel concentration in the films and affects the MWCNT growth at low temperature. The MWCNT synthesis was tested at growth temperature ranging between 335 and 520 °C. The growth of MWCNTs at 420 °C was only achieved by using Ni/C films with a high nickel content (60 at.%). These MWCNTs did not present considerable loss in their growth rate and structural quality compared to MWCNTs grown on classical substrates (Ni catalysts deposited on TiN), at higher temperature (520–600 °C). The results suggest that carbon saturation at the surface and subsurface of nickel catalysts of the Ni/C films is responsible for the improvement of MWCNT growth at low temperature.     

Easy synthesis of ordered mesoporous carbon containing nickel nanoparticles by a low temperature hydrothermal method

Ordered mesoporous carbons (OMCs) with embedded metallic nickel (Ni) nanoparticles have been directly synthesized by a simple and low temperature (50 °C) hydrothermal method. The synthesis involved the use of a triblock copolymer Pluronic F127 as the mesostructure directing agent, resorcinol (R) and formaldehyde (F) as carbon precursors, and Ni(NO₃)₂·6H₂O as nickel source. It consisted in the self-assembly of F127, Ni²⁺ salt and RF polymer in an acidic medium and further carbonization, where the Ni²⁺ was captured by the network of F127/RF and further reduced into metallic Ni nanoparticles. The resultant Ni/carbon materials were characterised by X-ray diffraction, thermogravimetric analysis, transmission electron microscopy and nitrogen sorption. Ni/carbon materials with a highly ordered mesostructure were obtained using equal moles of resorcinol and formaldehyde molar ratio (R/F = 1/1), whereas an excess amount of formaldehyde (R/F = 1/2) was found to not form an ordered carbon structure. The results showed that nickel particles, with sizes of ∼10–50 nm, were homogeneously dispersed in the carbon matrices, while the pore mesostructure remained intact. The homogeneous Ni/carbon composites synthesized by this easy hydrothermal route have been demonstrated to be effective molecular adsorbents for magnetic separation.     

Structural, electrical and magnetic properties of carbon-nickel composite thin films

Carbon-nickel composite thin films (600 nm thick) were prepared by dc magnetron sputtering of Ni and C at several temperatures (25-800 °C) on oxidized silicon substrates. By transmission electron microscopy it was found that the composite consisted of Ni (or Ni₃C) nanoparticles embedded in a carbon matrix. The metallic nanoparticles were shaped in the form of globular grains or nanowires (of the aspect ratio as high as 1:60 in the sample prepared at 200 °C). The carbon matrix was amorphous, or graphite-like depending on deposition temperature. At low deposition temperatures T_S (25-400 °C) the Ni₃C nanoparticles were of hcp phase. Samples prepared at T_S ? 600 °C contained ferromagnetic fcc Ni nanoparticles. A correlation was found between the structural, electrical and magnetic properties of the composites. To characterise the films, dependences, such as resistivity vs. temperature, current vs. voltage, differential conductivity vs. bias voltage, and magnetoresistivity, were determined. For example, the tunneling effect was found in samples in which the metallic nanoparticles were separated by 2-3 nm thick amorphous carbon. When the metallic nanoparticles were connected by graphite-like carbon regions (having a metallic conductivity, in contrast to a-C), the temperature coefficient of the resistivity became slightly positive. An anisotropic magnetoresistivity of ∼0.1% was found in the sample that contained ferromagnetic columnar fcc Ni. Zero magnetoresistivity was found in the sample in which the metallic nanoparticles were of non-magnetic hcp phase.     

尿素燃烧法制备镍基甲烷化催化剂及其催化反应性能

以拟薄水铝石、硝酸镍以及镁、钴、镧和铁的硝酸盐为原料,尿素为燃烧剂,采用尿素燃烧法制备系列镍基(以及含助剂)甲烷化催化剂。通过XRD和BET等对催化剂结构进行表征,采用固定床反应器评价催化剂的合成气甲烷化催化反应性能,考察Ni含量、尿素与原料质量比、焙烧温度和不同助剂等对催化剂结构和性能的影响,评价催化剂的稳定性。结果表明,Ni O质量分数为7.5%~44.8%时,采用尿素燃烧法均可制备γ-Al2O3为载体的镍基甲烷化催化剂,最佳制备条件为:尿素与原料质量比3∶1,焙烧温度450℃,燃烧时间40 min。26.1%Ni O/γ-Al2O3催化剂表现出较好的催化性能,在230℃和常压条件下,CO转化率和CH4选择性分别达99.5%和98.3%。26.1%Ni O-2.6%La2O3/γ-Al2O3催化剂在(230~700)℃经过多次升降反应温度和1 460 h的长周期稳定性测试,表现出较好的稳定性和耐热冲击性能。     

纳米镍粉的固相合成及其催化活性研究

介绍了以NiSO₄·6H₂O和NaOH为原料，固相法合成镍纳米粉。通过XRD、TEM、SEM和XPS等测试手段对产物表面结构进行表征。结果表明，产物为球形分布均匀的纳米镍粉，平均粒径为(30±5) nm。同时考察了不同还原温度和时间下得到的产物的催化活性以及反应中温度、压力和含量等对硝基苯加氢还原催化活性的影响，并在相同的条件下，和Raney Ni进行比较。还原实验表明，400 ℃还原4 h的产物质量分数为4.13%时,硝基苯转化率高达26.26%,催化加氢活性高于Raney Ni,是相同条件下Raney Ni的9倍左右。压力为0.8 kPa时，硝基苯转化率高达76.42％。     

碳源对Mo2C/SAPO-11催化剂制备及正庚烷异构化的影响

采用程序升温法制备了Mo₂C/SAPO-11催化剂,以正庚烷为模型分子,在固定床连续流微反装置上考察了分别采用正戊烷和正庚烷做碳源,对催化剂制备和异构化的影响。在400 ℃,氢压1.5 MPa,氢烃体积比为200∶1,空速1 h^-1条件下,正庚烷转化率达到81.39%,选择性68.67%,异构产物收率55.89％,连续反应120 h,异构化活性未见明显降低。     

金属蜂窝载体表面负载活性氧化铝涂层的研究

采用高温氧化法对合金FeCrAl金属基体进行预处理，使用AlOOH胶浸渍活性涂层，考察了氧化温度、氧化时间、料浆配方、制备条件以及焙烧温度等因素对涂层的影响。利用XRD、SEM、BET和超声波振动等方法研究了样品的表观性能和涂层的结合性能。结果表明，950 ℃氧化10 h的氧化处理可以在金属基体上形成粗糙的表层，增加涂层粘结能力。在料浆的制备过程中，加入添加剂以及提高活性涂层的焙烧温度都可以明显提高涂层与金属载体的结合力,得到的涂层牢固，比表面积达212 m²·g^-1，满足工业应用要求。