采用单晶(SingleSite)催化剂气相法聚乙烯生产技术

1 前言聚乙烯广泛用于食品包装、饮料容器、汽车、电气机器、土木、建材、农业资材、医疗器械等领域,是日本国内生产量达280万 t/a 的大型通用树脂。裂乙烯按照其结构大致分为低密度聚乙烯(LDPE)、高密度聚乙烯(HDPE)以及线性低密度聚乙烯(L—LDPE)

Enhanced photocatalytic hydrogen generation of mesoporous rutile TiO_2 single crystal with wholly exposed {111} facets

The development of semiconductor photocatalysts with highly reactive facets exposed has great potential to improve their photocatalytic reactivity. We report the synthesis of mesoporous rutile TiO 2 single crystals with tunable ratios of {110} and {111} facets through the seeded-template hydrothermal method. With increasing the amount of morphology controlling agent NaF,the facet ratio of {111} to {110} increases,and eventually the mesoporous rutile TiO 2 single crystals with wholly exposed {111} reactive facets are obtained. The resultant faceted mesoporous single crystals exhibit a superior photocatalytic performance of hydrogen evolution to mesoporous single crystals with a large percentage of thermodynamically stable {110} facets,as well as the solid rutile single crystals. ？ 2015,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.

Effect of the degree of dispersion of Pt over MgAl_2O_4 on the catalytic hydrogenation of benzaldehyde

One of the central tasks in the field of heterogeneous catalysis is to establish structure‐function relationships for these catalysts,especially for precious metals dispersed on the sub‐nanometer scale.Here,we report the preparation of MgAl2O4‐supported Pt nanoparticles,amorphous aggregates and single atoms,and evaluate their ability to catalyze the hydrogenation of benzaldehyde.The Pt species were characterized by N2adsorption,X‐ray diffraction(XRD),aberration‐corrected transmission electron microscopy(ACTEM),CO chemisorption and in situ Fourier transform infrared spectroscopy of the chemisorbed CO,as well as by inductively coupled plasma atomic emission spectroscopy.They existed as isolated or neighboring single atoms on the MgAl2O4support,and formed amorphous Pt aggregates and then nanocrystallites with increased Pt loading.On the MgAl2O4support,single Pt atoms were highly active in the selective catalytic hydrogenation of benzaldehyde to benzyl alcohol.The terrace atoms of the Pt particles were more active but less selective;this was presumably due to their ability to form bridged carbonyl adsorbates.The MgAl2O4‐supported single‐atom Pt catalyst is a novel catalyst with a high precious atom efficiency and excellent catalytic hydrogenation ability and selectivity.

Large-scale preparation of fernwort-like single-crystalline superstructures of CuSe as Fenton-like catalysts for dye decolorization

A simple green hydrothermal template-free method was developed to prepare single-crystalline superstructures of fern- wort-like copper selenide （CuSe） in large-scale by using polyvinylpyrrolidone （PVP） as both reductant and surfactant for the first time. Time-dependent morphologic evolution was made in order to explore the formation mechanism of the as-prepared product. The copper selenides with different morphologies, phases and structural forms could be prepared by varying the synthesis parameters, such as precursor molar ratios, precursor combinations, and the molecular weight of PVP. The fernwort-like superstructures of CuSe show excellent Fenton-like catalytic activities in degrading malachite green （MG） and rhodamine B （RhB）. These catalysts play an important role in the degradation process of MG and RhB solution with the aid of H202 which can yield highly reactive hydroxyl radicals （HO.）. Besides, the as-prepared CuSe catalyst is stable and reusable, thus it could be applied to the treatment of the dye contaminated waste water.