负载型催化剂催化二氧化碳和环氧化合物共聚的研究进展

为了实现二氧化碳与环氧化合物共聚制备脂肪族聚碳酸酯过程中催化剂的循环利用,提高产物的热力学和力学性能,对其均相催化剂进行载化,即将活性组分/中心负载在无机或高分子载体上是一条有效的途径。文中综述了二氧化碳和环氧化合物共聚中负载型催化剂的研究进展,重点对羧酸锌催化体系、SalenMX催化体系、稀土三元催化体系等不同负载型催化剂的制备方法、催化效率、产物性能及优缺点进行了系统阐述,为负载型催化剂的进一步研究提供了参考。     

CO2共聚单体及产物改性的研究进展

CO2共聚物的研究开发在环境保护、资源再利用及新材料研究领域中都具有重要的意义。CO2共聚单体是影响其共聚产物结构、性能及成本的重要因素。文中综述了与CO2催化共聚的各类单体的研究进展及产物理化性能的特点,这些单体主要包括环氧化合物、烯类化合物和可再生型环氧烷烃;并介绍了通过三元共聚以调控分子链单元与分子链结构,从而改善聚合产物的理化性能。进一步就今后CO2催化共聚的发展方向进行了探讨。     

聚苯乙烯负载茂钛族催化剂的研究

采用悬浮法和溶液法将带有不饱和双键的金属茂钛族化合物与苯乙烯、二乙烯苯进行共聚,分别合成了以聚苯乙烯为载体的健联型负载茂钛族催化剂。茂锆化合物比茂钛化合物容易与苯乙烯、二乙烯苯共聚。茂锆化合物的催化反应类似于活性聚合,聚合反应中存在不同的活性中心,该反应有别于纯自由基反应。     

与CO2催化共聚单体的研究进展

CO2共聚物的研究开发对环境保护、资源再利用及新材料研究领域都都具有重要的意义。与CO2共聚的单体是影响其共聚物结构、性能及成本的重要因素。综述了与CO2催化共聚单体的研究进展,这些单体主要包括二元共聚的环氧丙烷、环氧环己烷,三元共聚的某些单体。进一步就今后CO2催化共聚的发展方向进行了探讨,可望为CO2共聚物产业化发展提供参考。     

汽车尾气净化负载钯超微粒催化剂的研究

以复合稀土氧化物的γ-Al2O3为催化剂载体,将负载钯的超微粒子金属铁、钴、镍与γ-Fe2O3粉体混合成型焙烧制成催化刺.研究了复合稀土氧化物对γ-Al2O3表面积的影响,通过催化剂老化实验、丙烷化合物起燃温度检测和对模拟汽车尾气中丙烷、CO及NOx等物质的转化性能的研究,表明该型催化剂各性能较好.     

MCM-41负载戊二酸锌催化剂催化CO2和环氧丙烷的共聚反应

制备了MCM-41负载戊二酸锌催化剂(ZnGA/MCM-41),并采用热重分析、红外光谱和X射线衍射对催化剂进行了表征。结果表明,ZnGA与载体间存在相互作用,ZnGA能以更小的粒径均匀分散到MCM-41的表面。实验研究表明,该催化剂对于CO2与环氧丙烷(PO)共聚反应显示出较高的催化效率,并得到高分子量的聚碳酸亚丙酯(PPC);通过调节负载量和催化剂的用量,最高催化效率达到了89.5g聚合物/g ZnGA;共聚产物的红外光谱和核磁数据表明,所得共聚产物具有接近完全交替(>97.4%)的碳酸酯结构。     

Pd负载型介孔ZrO2-TiO2复合材料的设计合成及其CO催化氧化性能研究

以介孔结构的复合ZrO₂-TiO₂为载体负载活性组分, 制备了具有高CO催化氧化活性的Pd/ZrO₂-TiO₂与PdCu/ZrO₂-TiO₂负载型催化剂。XRD、TEM研究结果表明: 活性组分Pd、Cu物种可均匀分散于介孔载体中。系统考察了不同的催化剂载体、制备方法和助催化剂等对该介孔复合材料CO催化氧化性能的影响, 结果表明: 以ZrO₂-TiO₂为载体的催化剂其CO催化氧化活性明显优于以介孔Al₂O₃或介孔SBA-15为载体的催化剂; 一步法制备的介孔Pd/ZrO₂-TiO₂催化剂其CO催化氧化的低温活性较浸渍法制备的Pd/ZrO₂-TiO₂有很大提高; 并且Pd和Cu物种共负载的介孔ZrO₂-TiO₂复合催化剂具有最优的CO催化氧化活性, 其CO的完全催化氧化温度可降至170℃, O₂-TPD分析说明Pd和Cu之间的相互作用使得PdCu/ZT催化剂在更低温度具有氧化还原活性。     

聚苯乙烯负载钯催化剂合成及催化共聚性能研究

合成了聚苯乙烯负载邻菲咯啉/钯配合物催化剂(PS-phen/Pd(OAc)2和PS-phen/PdCl2)。采用红外光谱(FT-IR)、X光电子能谱(XPS)、元素分析(EA)、原子吸收(AAS)及热重分析(TGA)等手段对该负载钯催化剂的结构和性质进行了系统表征。评价了聚苯乙烯负载钯催化剂在苯乙烯与CO共聚反应合成聚酮(PK)中的催化性能,结果表明,在温度为65℃,CO压力为3.0 MPa的条件下,PS-phen/Pd(OAc)2和PS-phen/PdCl2的催化活性分别为1.02×104gPK/mol Pd.h和5.50×103gPK/mol Pd.h,循环使用三次后,催化活性分别降至570 gPK/mol Pd.h和97.4 gPK/molPd.h。负载催化剂PS-phen/Pd-Cl2和PS-phen/Pd(OAc)2催化得到的苯乙烯/CO共聚产物的重均分子量(-Mw)较大,分别为6.86×103g/mol和7.33×103g/mol。     

端羟基环氧环己烷-环氧氯丙烷共聚醚的合成与表征

采用三氟化硼乙醚(BF3.OE t2)作催化剂,乙二醇(EG)作起始剂,二氯甲烷(CH2C l2)作溶剂,制备了端羟基环氧环己烷-环氧氯丙烷(CHO-ECH)共聚醚,讨论了原料摩尔配比、聚合温度和聚合时间对共聚结果的影响,并采用IR和1H-NM R对共聚醚进行了结构表征。用该共聚醚制备的聚氨酯涂膜性能优良。     

CO与烯烃共聚反应钯系催化剂的研究进展

钯系催化剂具有较高的催化活性和选择性,一直是CO与烯烃共聚反应制备聚酮研究较多的催化体系。但由于其价格较高,严重制约了CO与烯烃共聚制备聚酮的工业化进程。系统分析了近几年来钯系催化剂的研究进展,包括钯种类、配体类型、钯的负载方式及反应介质的应用等。以期为制备新型、高效的钯催化剂提供思路,推动CO与烯烃共聚反应制备聚酮的工业化发展。     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.