碱性助剂对加氢脱硫催化剂性质及活性的影响

选择了一种碱性有机盐作为助剂合成加氢脱硫催化剂,通过N2吸附-脱附、XRD、CO_2-IR、NH_3-TPD、原位CO-IR和模型化合物加氢及FCC汽油脱硫反应,表征评价了碱性助剂对催化剂性质及反应活性的影响。通过对比发现了由于生成部分微孔导致含助剂催化剂的比表面积有所提高,孔容、孔径有所下降。由于助剂的加入使催化剂具有一定量的碱性吸附位,原位CO-IR表征证实含碱性有机盐助剂催化剂在硫化过程中会更多生成CoMoS相。通过模型化合物加氢反应和工业FCC汽油脱硫反应证实含碱性有机盐助剂催化剂具有一定的加氢异构能力,其在FCC汽油脱硫反应中的选择性更好,更适用于生产高辛烷值汽油。     

Synthesis and photocatalytic characterization of porous cuprous oxide octahedra

Porous cuprous oxide octahedra with a mean diameter of 1 μm have been successfully prepared with high yield via a hydrothermal reduction process at a low temperature. The growth mechanism and the influences of the poly(vinylpyrrolidone) (PVP) and citric acid have been discussed. And then, the samples were used as photocatalytic in the degradation of methyl red (MR). Thanks to the 3D architecture of the product, the photocatalytic performance has been significantly improved. We believe that the present work will open up to systematically explore ways to fabricate porous nanostructures and thus find use in a variety of applications.     

Synthesis and photo-catalytic degradation property of nanostructured-ZnO with different morphology

ZnO nanostructures with different morphology have been successfully fabricated by a simple relative low temperature approach at 90 °C for 5 h without surfactant assistance. These structures can be easily tailed using varied concentrations of sodium hydroxide (NaOH) and different amounts of the hydrazine hydrate (N₂H₄·H₂O). X-ray diffraction (XRD) result proves the formation of ZnO with wurtzite structure. Microstructure as revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicates that the rod-like and chrysanthemum-like ZnO nanostructures contain many radial nanorods, which grow along the [0001] direction. Furthermore, the as-prepared ZnO nanomaterials exhibit high activity on the photo-catalytic degradation of typical persistent organic pollutants (POPs), indicating that they are promising as semiconductor photo-catalysts.     

Simultaneous hydrogenation and hydroacylation of vinyl groups in polybutadiene by use of a rhodium catalyst

Vinyl groups in phenyl-terminated polybutadiene (1a) containing 99% unsaturation (27% vinyl group, 73% internal olefin), and for which the average M_n is 3400, were simultaneously hydrogenated and hydroacylated with various aromatic or heteroaromatic primary alcohols in the presence of the catalytic system RhCl₃.H₂O, PPh₃ and 2-amino-4-picoline. Sterically less hindered alcohols, such as benzyl alcohol, showed greater reactivity than sterically more hindered alcohols, such as 2-naphthylmethanol and heteroaromatic primary alcohols. Vinyl groups in phenyl-terminated polybutadiene (1b) containing 99% unsaturation (45% vinyl group, 55% internal olefin) and for which the average M_n is 1300 also showed similar reactivity toward various primary alcohols under identical reaction conditions.     

Well-dispersed perovskite-type oxidation catalysts

A novel technique for the preparation of highly dispersed rare-earth perovskite LaCoO₃ catalysts was developed. Using the conventional complexation and pyrolysis methods, an etchable component, zinc oxide (ZnO), was introduced into the precursor by adding zinc nitrate during preparation. After calcination, the independent ZnO phase was extracted by an aqueous NH₄Cl solution, resulting in well-dispersed LaCoO₃ catalysts with a surface area of over 30 m²/g. DTA-reaction tests using CO oxidation as the model reaction were performed as a quick means to illustrate the higher catalytic oxidation activities of the prepared LaCoO₃ catalysts mainly due to their high surface area.     

Selective catalytic reduction of NO by hydrocarbons on Ga2O3/Al2O3 catalysts

Catalytic properties of supported gallium oxides have been examined for the selective reduction of NO by CH₄ in excess oxygen. The activity was greatly affected by the support; Ga₂O₃/Al₂O₃ (Al₂O₃ supported Ga₂O₃) and Ga₂O₃–Al₂O₃ mixed oxide exhibited high activity and selectivity as comparable to Ga-ZSM-5, while unsupported Ga₂O₃ and the other supported Ga₂O₃ were ineffective. For Ga₂O₃/Al₂O₃, the activity changed with Ga₂O₃ content, and was highest at about 30 wt% Ga₂O₃, which corresponds to a theoretical monolayer coverage. Gallium oxide highly dispersed on Al₂O₃ is considered to be responsible for the high activity and selectivity. The reaction characteristics of Ga₂O₃/Al₂O₃ were studied and compared with Ga-ZSM-5 and Co-ZSM-5. Ga₂O₃/Al₂O₃ exhibited the highest activity and selectivity at high temperature. In addition, Ga₂O₃/Al₂O₃ showed higher tolerance against water than Ga-ZSM-5. C₃H₈ and C₃H₆ were also evaluated as reducing agents, and Ga₂O₃/Al₂O₃ showed higher activity than Ga-ZSM-5 above 723 K achieving almost complete reduction of NO to N₂.     

Nuclear Magnetic Resonance of Physisorbed 129Xe Used as a Probe to Investigate Porous Solids

Xenon is an inert gas with a large electronic environment that makes it sensitive to any interaction, even physical. In the case of ¹²⁹Xe isotope (spin 1/2), the resulting electronic perturbation is directly transmitted to the nucleus and, therefore, affects the nuclear magnetic resonance chemical shift. In this review, we report exhaustively up to 1996 the many applications of this technique in both fundamental and applied research in the fields of microporous and mesoporous solids.     

Partial Oxidation of Propane Using Dense Carbon Dioxide

The present work was aimed at investigating activity and selectivity of various catalysts for the partial oxidation of propane in sc‐CO₂ atmosphere. Catalytic experiments were performed in a stirred batch reactor. This paper reports on the used reactor system and first results of a catalyst screening using different metal (oxide) catalysts as well as the variation of the reaction conditions.