Efficiency of Gold Nano Particles on the Autoxidized Soybean Oil Polymer: Fractionation and Structural Analysis

Polyunsaturated plant oils have gained great interest as monomers to produce biodegradable polymers obtained from renewable resources due to the limited existing sources of petroleum oil and environmental issues. Soybean oil was autoxidized by exposure to atomospheric oxygen at room temperature with or without the presence of gold nanoparticles (Au NPs) 5–41 days. When the autoxidation process was catalyzed with Au NPs, the molecular weight of the oxidized oil was increased in 5 days. In contrast to this, without Au NPs, the oxidized oil was still a fluidized liquid. Autoxidized soybean oil polymer in toluene solution with gold NP showed a surface plasmon resonance at λ_max = 540 nm in a UV–VIS spectrometer and a fluorescence emission spectrum at λ_max = 450 nm, when it was irradiated at λ_max = 390 nm. The higher molecular weight of the polymeric oils was successively fractionated by the extraction from the solvent‐non‐solvent mixture CHCl₃/petroleum ether with the volume ratio of 5:15. Three polymeric oils fractions with different molecular weight (ca 1000, 4000, and 40,000 g/mol) were obtained. GC–MS analysis, ¹H‐NMR and GPC techniques were used in the structural analysis of the fractionated polymeric oils.     

用于合成4-(反-4′-正丙基环己基)环己酮催化剂的研究

环己酮衍生物作为一种重要的液晶中间体,其制备方法尤其是催化加氢合成法的研究受到关注。以质量分数55%HNO₃处理的工业椰壳活性炭为载体,采用等体积浸渍与沉积-沉淀结合的方法制备0.9%Au-5%Pd/C-IM-DP催化剂,并应用于选择性加氢制备4-(反-4′-正丙基环己基)环己酮的反应。以环己烷作为溶剂,在反应温度150 ℃和反应压力0.8 MPa条件下反应2 h,原料转化率为98.7%,目标产物选择性达91.2%。相比于单金属5%Pd/C催化剂,0.9%Au-5%Pd/C-IM-DP催化剂具有较高的活性和选择性。通过XRD和TEM等对催化剂组成和形貌进行表征分析,结果表明,Au和Pd均以单金属颗粒形式存在,而Pd和Au之间的氢溢流作用可能是催化剂具有优异性能的原因。     

Model oxide-supported metal catalysts: energetics,particle thicknesses,chemisorption and catalytic properties

Many industrially important catalysts consist of late transition metal particles supported on the surfaces of oxide materials. Our studies of such systems using model catalysts consisting of metal films vapor deposited onto the surfaces of single-crystalline oxides are reviewed here. Systems studied include Cu on ZnO, Pt on ZnO, Au on TiO₂ and Cu, Ag and Pb on MgO. A unique adsorption microcalorimeter was developed to measure directly the energetic stability of the metal atoms on the oxide surfaces and the adhesion energy at the metal/oxide interface, which clarify the structural and chemisorption properties of the ultrathin metal particles. The structure of the oxide surface and the metal particles was elucidated by low-energy electron diffraction (LEED), low-energy ion scattering spectroscopy (ISS), angular-resolved X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD). The electronic character of the metal particles was revealed by XPS, Auger electron spectroscopy (AES), band-bending and work function measurements. Sintering rates were measured by temperature-programmed ion scattering spectroscopy (TPISS). The chemisorption properties of these particles and their catalytic reactivity were monitored by mass spectroscopy and temperature-programmed desorption (TPD).     

不同还原剂对金纳米颗粒合成的影响

利用种子生长法,分别用盐酸羟胺和抗坏血酸作还原剂合成了不同大小的金纳米颗粒.研究了不同还原剂对金纳米颗粒形貌、粒径和单分散性的影响.实验结果表明,用盐酸羟胺作还原剂合成的金纳米颗粒的单分散性较好.这主要是由于盐酸羟胺的还原性弱于抗坏血酸,反应过程中不会发生二次成核.     

花片状钌纳米颗粒的控制合成

以三氯化钌为前驱体、聚乙烯吡咯烷酮（PVP）为稳定荆、三缩四乙二醇（TEG）和Zn粉为还原剂,于170℃反应2h。再加入适量十六烷基三甲基溴化铵（CTAB）,继续反应4h成功制得花片状Ru纳米颗粒。反应体系中最适宜RuCl2：PVP：CTAB：Zn（摩尔比）为1：20：1：1．5。产物用透射电子显微镜（TEM）、X-射线粉末衍射（XRD）、紫外可见吸收光谱（UV—Vis）等进行了表征。     

Identification of valence shifts in Au during the water-gas shift reaction

In situ X-ray absorption spectroscopy (XAS) has been performed to investigate the active site on Au-based catalysts in the water-gas shift (WGS) reaction. The surface area and hence the WGS activity is higher for AuTiO₂ catalysts supported on carbon nanofibres (CNF) than TiO₂. The WGS reaction rate depends on the Au coordination number with an apparent maximum close to eight which corresponds to a particle size of approximately 2.5–3.0 nm. A likely cause for the changes in the electronic structure of Au is the adsorption of CO on the surface, which also creates a small positive charge in the Au atoms. The catalytic activity significantly improves when titania is present compared to Au deposited directly on CNF.     

Methanol Steam Reforming Over NiAl and Ni (M) Al Layered Double Hydroxides (M = Au, Rh, Ir) Derived Catalysts

This paper deals with an experimental investigation concerning steam reforming of methanol at 280, 340 and 380 °C over NiAl and Ni (Au, Rh or Ir)Al layered double hydroxides (LDHs) derived catalysts. Incorporation of noble metal ions into the NiAl-LDH framework was evidenced by XRD, TGA and TEM techniques. High selectivity to H₂ and CO₂ with less than 5% (volume) CO and trace CH₄ was observed over the NiAl-LDH catalyst. Whereas CO and H₂ are major products at lower temperatures after addition of Au, Rh and Ir to the NiAl-LDH system. They are significantly reduced with the concomitant increase in CH₄ and CO₂ as the temperature increased.     

Zn(Al)O复合氧化物负载Au催化剂催化氧化甘油制备1,3-二羟基丙酮

以尿素为沉淀剂,采用均匀沉积沉淀法制备了Zn(Al)O复合氧化物负载Au催化剂,并用于无碱条件下催化氧化甘油制备1,3-二羟基丙酮（DHA）反应,值得注意的是随着载体中Zn/Al摩尔比的不同,负载Au催化剂的催化活性和产物DHA的选择性呈现明显差距。结合X射线衍射（XRD）、X射线光电子能谱（XPS）、透射电镜（TEM）、CO吸附傅里叶变换红外光谱（CO吸附FTIR）等表征手段,发现载体Zn(Al)O复合氧化物中Zn/Al摩尔比会影响表面氧物种的含量并进一步会影响催化剂的催化活性和选择性。当Zn/Al摩尔比为7∶1、反应温度为80℃、氧气压力为10bar、反应2h时获得最佳的甘油转化率（58.5%）和DHA的选择性（95.3%）。同时,还考察了反应温度、反应时间、反应压力及载体的焙烧温度对催化性能的影响,并发现反应条件对催化剂的催化活性和选择性均有不同程度的影响。此外,以Au/Zn(Al)O-7∶1催化剂为基准考察了催化剂的稳定性,并通过表征手段分析了催化剂失活的主要原因。     

(Au,Ag,Cu)/SiO_2二元金属单分散复合薄膜非线性光吸收性的Mie理论模拟

采用修正的Mie理论模拟计算了(Ag, Cu)/SiO₂, (Au, Cu)/SiO₂和(Ag, Au)/SiO₂二元单质金属纳米颗粒分散体系的理论吸收光谱. 研究发现, 二元金属纳米颗粒分别以单质金属形式存在时, 吸收光谱分别在2个波段处出现表面等离子共振吸收峰, 二元金属的相对含量影响吸收峰的峰强, 与峰位无关. 理论模拟吸收光谱与前人实验结果符合良好.     

LaFe11.6Si1.4合金的常温吸放氢行为

利用化学浴法制备了由六棱锥纳米分枝组成的多级分层花型结构的ZnO,并采用溶剂热法在所得ZnO材料表面均匀修饰Au纳米粒子.系统地研究了不同Au纳米粒子修饰量对ZnO气敏性能的影响.结果表明:Au纳米粒子的修饰能显著提高ZnO对丙酮气体的敏感性,当Au修饰量为10％(质量分数),工作温度为270℃时,ZnO表现出最佳灵敏度和选择性,是实际应用中良好的气体敏感候选材料.