Characteristics of nanosized ruthenium metal by chemical reduction method

Nano-sized Ru metals have been prepared by the chemical reduction of ruthenium chloride and ruthenium hydroxide. Sodium borohydride was used as a reducing agent. The samples have been characterized by elemental analysis, X-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The preparation method greatly affects the composition and surface area of the material. All the samples show nanosized particles. However, samples prepared by reduction of ruthenium hydroxide had a lower surface area and larger particle size than those prepared by reduction of ruthenium chloride. Residual amount of boron was present in the samples. The samples demonstrate amorphous structure.     

Hydrogenation of p-Chloronitrobenzene on Nanosized Modified NiMoB Catalysts

NiMoB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effect of additives (Pd, La, Fe and Co) on the catalytic properties of NiMoB in the hydrogenation of p-chloronitrobenzene. The catalysts were prepared by chemical reduction method using sodium borohydride as the reducing agent. The molar ratios of Ni/Mo/B/additives in the starting materials were 0.4/1/3/0.1. The catalysts were characterized by inductively coupled plasma-mass spectrometry, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 1.2?MPa H₂ pressure and 333–353?K. Adding additives decreased the particle size of modified-NiMoB catalyst, suppressed the growth of the crystalline structure of NiMoB and helped the NiMoB nanocluster maintain its amorphous state. The reaction activity is in the order of the following: Pd-NiMoB?>?La-NiMoB?>?Co-NiMoB?>?NiMoB?>?Fe-NiMoB. Pd itself is the active metal for hydrogenation, but NiPd bimetallic alloy was too active resulting in low selectivity of chloroaniline. The other additives were in the form of hydroxide and acted as a spacer to prevent NiMoB catalysts from sintering and aggregation.     

对氯硝基苯在含镧的镍钼硼奈米触媒上的氢化反应

钼和镧是好的镍硼触媒的促进剂, 对于对氯硝基苯氢化反应有好的效果, 因此同时加入钼和镧在镍硼触媒上应该是有趣的研究题目. 本研究利用化学还原法制备了一系列含有不同量镧的镧钼镍触媒, 醋酸镍、钼酸胺及硝酸镧同时加入含有甲醇的水溶液中. 以X光绕射, 穿透式电子显微镜、高分辨率电子显微镜及X光光电能谱仪鉴定了这些触媒. 对氯硝基苯氢化反应是在批次反应器中于333 K、1.2 MPa氢气压力及500 r/min转速下操作. 即使在镍钼硼中加入很少量的镧, 对提高活性及对氯苯胺的选择性都有显著的效果, 加入适量的镧可以抑制镍钼硼的长范围的结晶排列, 并保持镍钼硼在非结晶状态. 镧以氧化态存在, 其功效为阻隔物, 避免镍钼硼聚集, 但是过量的镧会有相反的效果, 镧和镍的适当比例是0.2.     

The Synthesis and Characteristics of Vanadoaluminosilicate MCM-41 Mesoporous Molecular Sieves

A series of vanadoaluminosilicate MCM-41 mesoporous molecular sieves with various compositions have been hydrothermally synthesized. Hexadecyltrimethylammonium bromide was used as a surfactant in the synthesis. The samples were characterized with nitrogen sorption, X-ray diffraction, differential thermal analysis, thermogravimetric analysis, Fourier transform-Infrared spectroscopy, UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, and solid state NMR. The solid products had the MCM-41 structure and contained only atomically dispersed vanadium and aluminum consistent with framework vanadium and aluminum. The samples were hydrophobic and contained large amount of surfactant in the as-synthesized samples. The surfactant could be removed upon calcination at 450°C. N₂ sorption measurements and TEM demonstrate the high mesoporosity of [V, Al]-MCM-41. The incorporation of vanadium and aluminum into MCM-41 decreased the surface area to some extent. The morphologies of all the samples were the agglomerate of plates. ²⁹Si MAS NMR shows that the pore wall is amorphous. ²⁷Al MAS NMR shows that all of aluminum species were tetrahedrally coordinated even after calcination at 550°C.     

Photocatalytic reduction of carbon dioxide with water using InNbO4 catalyst with NiO and Co3O4 cocatalysts

InNbO₄ was prepared by the solid-state reaction method. Various cocatalysts were added on InNbO₄ by the incipient-wetness impregnation method. The effects of co-catalyst and pretreatment conditions on the photocatalytic activity of InNbO₄ for photoreduction of carbon dioxide were investigated. NiO–InNbO₄ and Co₃O₄–InNbO₄ were pretreated by reduction at 500 °C for 2 h and subsequent oxidation at 200 °C for 1 h. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The characterization results of NiO–InNbO₄ catalysts after pretreatment showed the presence of highly crystalline NiO and monoclinic Nb₂O₅. NiO–InNbO₄ with reduction–oxidation pretreatment exhibited the highest activity due to the presence of core–shell type Ni⁰ and NiO on the surface and the presence of a small amount of Nb₂O₅ as a promoter.     

Characterization of V-MCM-41 Mesoporous Materials

A series of vanadosilicate V-MCM-41 mesoporous materials with various compositions have been synthesized using vanadium sulfate as the source of vanadium. Hexadecyltrimethylammonium bromide was used as a surfactant in the synthesis. The samples were characterized with nitrogen sorption, X-ray diffraction, framework FTIR, diffuse reflectance UV-visible spectroscopy, differential thermal analysis, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The results show that the solid products had the MCM-41 structure and contained only atomically dispersed vanadium consistent with framework vanadium in V-MCM-41. N₂ sorption measurements and TEM demonstrated the high mesoporosity of V-MCM-41. The incorporation of vanadium into MCM-41 decreased the surface area to some extent. The morphology of V-MCM-41 was plate with stepped and smooth surfaces. TEM reveals a regular hexagonal array of uniform channels with curved and rectilinear morphologies. The hexagonal array structure of uniform pore size was observed by TEM. It is proved that the pores were highly aligned.     

Synthesis of Micropore/Mesopore Composite Materials

The objective of this study was to synthesize micropore-mesopore composite materials by two-step crystallization. The colloidal MFI was first synthesized using a structure-directing agent tetrapropylammonium hydroxide as a template in the first step. This colloid was then self-assembled to form mesoporous structure by using cetyltrimethylammonium bromide as a surfactant. These materials were characterized by powder X-ray diffraction, nitrogen sorption, SEM and TEM. Due to the thick walls produced, it cannot sustain the local strain caused by the crystallization: the mesostructure is collapsed upon heating. The mixed phases of MFI and MCM-41 were obtained by optimizing the synthesis times and reaction temperatures.