Supported honeycomb monolith catalysts for high-temperature ammonia decomposition and H2S removal

Catalysts that have potential in simultaneous removal of H₂S and NH₃ decomposition were developed. The monolith supports of high surface area and acceptable mechanical strength based on titania and silica–alumina precursors were prepared and tested. Preparation routine and composition of Mn, Fe and Cu oxides supported honeycomb catalysts have been optimized. Impregnated and washcoated monolith catalysts were tested in ammonia high-temperature decomposition.     

Organofunctionalized catalyst surfaces highly active and selective for carbon–carbon bond-forming reactions

This article illustrates two types of organofunctionalized heterogeneous catalysts for variety of organic carbon–carbon bond-forming reactions, summarizing our previous reports and also presenting new data. Organic amines with an alkoxysilane moiety were immobilized on inorganic silica-alumina surfaces (SA-NR₂) by simple silane-coupling reactions between the silica-alumina surface (SA) and the alkoxysilane. This SA-NR₂ acted as acid–base bifunctional heterogeneous catalysts for carbon–carbon bond-forming reactions, such as cyano-ethoxycarbonylation, Michael reaction of nitriles, and nitro-aldol reaction. These reactions did not occur with either SA or homogeneous amine compounds. In addition, the mixture of SA and homogeneous amine showed low catalytic activity due to undesirable acid–base neutralization reaction. Achiral organic silane-coupling reagents with a variety of functional groups were also immobilized on a SiO₂ surface that had been immobilized with chiral bis(oxazoline) (BOX), to which Cu ions were coordinated to make chiral Cu–BOX complexes on the SiO₂ surface. The SiO₂-supported Cu–BOX complex catalyst functionalized with achiral 3-methacryloxypropyltrimethoxysilane dramatically increased enantioselectivity in the asymmetric Diels–Alder reaction of cyclopentadiene and 3-acryloyl-2-oxazolidinone. The organofunctionalized catalysts showed much better performances for the C–C bond-forming reactions compared to the corresponding homogeneous systems. The heterogeneous catalysts thus obtained were characterized by solid-state ¹³C and ²⁹Si MAS NMR, FT-IR, UV/vis, XAFS, ESR, XRF, and elemental analysis.     

An alternative atmospheric-pressure cold plasma method for synthesizing Pd/P25 catalysts with the assistance of ethanol

Atmospheric-pressure (AP) cold plasma has experienced a growing interest recently due to its simplicity and high efficiency for preparing supported metal catalysts by using the active hydrogen species generated from explosive H₂ gas. In this communication, we report an alternative AP cold plasma method for synthesizing supported Pd catalysts using Ar gas and ethanol instead of explosive H₂ gas and toxic reducing agents. The TOF value of the prepared Pd/P25 catalyst at 120 °C is 3.1 times of that prepared by cold plasma using H₂ gas due to the protection of the formed carbon species. AP cold plasma using ethanol as the origin of active hydrogen species is safer and more efficient than that using H₂ gas, and may also have great potentials to synthesize other supported metal catalysts.     

Selective separation of cobalt and nickel by supported liquid membranes

The selective separation of cobalt from acidic media, containing both equimolar and nonequimolar mixtures of cobalt and nickel, was examined by supported liquid membranes using Alamine 336 as mobile carrier dissolved in various diluents. The membrane support was microporous hydrophobic polypropylene Celgard 2500 (25 μm thick, 0.209 × 0.054 μm pore size and 55% porosity). Acetic acid-Na acetate buffer was used for the adjustment of the feed pH which was critical. Various parameters were experimentally studied and the optimum conditions were determined.     

企业级即时通讯技术及其应用

基于网络的协同工作是办公自动化的高层次应用,也是其发展的趋势。而计算机通信交流技术则是网络协同办公的技术的核心。本文介绍了计算机通信交流技术在协同办公中的作用,进而对其最基础与重要的的即时通讯技术进行概述,介绍了局域网即时通讯技术的主流技术,并给出了架构实例。     

支持计算机协同操作的虚拟教室的研究开发

基于WWW的现代远程教学是远程教育的重要方向,网上虚拟教室是提高远程教学的重要手段。文章概述了网上教学的交互性、虚拟教室(VirtualClassroom)、计算机支持协同操作(CSCW)的原理,设计了支持协同操作、交互性良好的网上虚拟教室的基本结构,并研究了利用协同操作来解决网上虚拟教室中学习者与教师、学习者与学习者之间的进行交互的关键技术,实现了一个虚拟教室系统。     

Structural diversity of sphingomyelin microdomains

In cells plasma membrane, sphingomyelin (SM) plays a key role in the formation of a category of lipid microdomains enriched in cholesterol (Chl) often referred to as rafts. Atomic force microscopy (AFM) was used to analyze the mesoscopic topography of enriched SM microdomains in supported bilayers made of SM/dioleoylphosphatidylcholine (SM/DOPC) and SM/palmitoyl-oleoyl-phosphatidylcholine (SM/POPC) equimolar mixtures, in buffer, at room temperature. Gel–fluid phase separation occurs in both SM/DOPC and SM/POPC bilayers. The gel phase SM-enriched microdomains adopt a variety of size, shape and mesoscopic structure, from homogeneous flat domains of a few hundreds of nanometer in diameter to domains of several micrometers made of closely packed globular structures. Gel–gel phase separation in SM domains is also observed which gives rise to different structures for the diunsaturated and the mixed-saturated PC species. These differences could also extend to the interactions with Chl. This suggests that studies on rafts formation commonly performed using SM/DOPC mixture as a model should also include the physiologically more relevant POPC species.     

Ar assisted carbidization of TiO2 (1 1 0) supported Mo nanoparticles by decomposition of C2H4

Ar⁺ assisted carbidization of Mo nanoparticles supported on TiO₂ (1 1 0) is studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In order to activate the diffusion of carbon into the bulk of Mo nanoparticles we applied Ar ions (1 keV) during the exposure of C₂H₄. XPS exhibited that the decomposition of C₂H₄ at 850 K accompanied by ion bombardment results in an almost complete carbidization of nanocrystalline Mo while this treatment performed without ion bombardment results only in the carbidization of the particle surface. The modification of the crystallinity of the Mo-carbide particles was deduced from STM measurements.     

RECENT ADVANCES AND FUTURE ASPECTS IN THE LOW-TEMPERATURE CONVERSION OF SATURATED HYDROCARBONS

A brief review on the advances and future aspects in the low-temperature activation of carbon–hydrogen and carbon–carbon bonds in hydrocarbons is presented. Particular attention is given to a catalyst formulation for low-temperature conversion of hydrocarbons. An efficient catalyst design method for low-temperature activation of saturated hydrocarbons has been worked out using metal evaporation techniques. The characteristic property of such catalysts is the presence of metal particles on the surface in an atomically dispersed state. Some of the prepared catalysts cause complete hydrocracking of alkanes and cycloalkanes at 423–463K.     

负载型Pd催化剂

介绍了制备负载型钯催化剂的几种方法，以及它在反应中的应用。阐述了几种催化剂载体的优点，最后对这种催化剂的前提提出展望。