Au/α-Fe_2O_3 催化剂上金活性物种的分析(英文)

采用沉积沉淀法制备了CO低温氧化 Au/α-Fe2O3催化剂,利用 X 射线衍射(XRD)、X 射线光电子能谱(XPS)、BET 比表面测定、程序升温还原(H2-TPR)等表征技术,对比了制备过程 pH 值的微小变化、焙烧及光线照射对催化剂结构及催化性能的影响,探明了 Au/α-Fe2O3催化剂的活性物种。结果表明,110 ℃处理的 Au/α-Fe2O3催化剂表面同时存在 Au3+、Au0以及过渡态 Auδ+(0δ1),它们对 CO 氧化的活性顺序为 Au3+Auδ+Au0;pH 值为 8 条件下制备的催化剂 Au3+含量高、比表面积大,催化性能最好;高温焙烧使氧化态金还原的同时也使载体比表面积严重缩小,催化活性显著下降;紫外线照射可以引起 Au3+的逐渐还原以及 Au0 颗粒的生长,其催化失活作用弱于高温焙烧。     

Analysis of the Active Au Species on Au/α-Fe2O3 Catalyst

采用沉积沉淀法制备了CO低温氧化 Au/α-Fe2O3催化剂,利用 X 射线衍射(XRD)、X 射线光电子能谱(XPS)、BET 比表面测定、程序升温还原(H2-TPR)等表征技术,对比了制备过程 pH 值的微小变化、焙烧及光线照射对催化剂结构及催化性能的影响,探明了 Au/α-Fe2O3催化剂的活性物种。结果表明,110 ℃处理的 Au/α-Fe2O3催化剂表面同时存在 Au3+、Au0以及过渡态 Auδ+(0<δ<1),它们对 CO 氧化的活性顺序为 Au3+>Auδ+>Au0;pH 值为 8 条件下制备的催化剂 Au3+含量高、比表面积大,催化性能最好;高温焙烧使氧化态金还原的同时也使载体比表面积严重缩小,催化活性显著下降;紫外线照射可以引起 Au3+的逐渐还原以及 Au0 颗粒的生长,其催化失活作用弱于高温焙烧。     

La助剂对Pd-AL2O3催化C3H8氧化性能的研究

采用不同稀土La前驱体浸渍掺杂改性Pd/γ-Al2O3催化剂,利用多功能催化性能评价装置测试不同催化剂的C3H8催化氧化性能,并通过H2-TPR、XRD、XPS等手段对催化材料进行结构表征,结果表明：La能促进贵金属钯分散,增强钯与载体相互作用,稳定高活性Pd2+物种,从而提高了催化剂的C3H8催化氧化性能。在选用不同La前驱体改性的Pd/γ-Al2O3催化剂中,硝酸镧改性效果最佳,能更好地促进活性金属钯的分散和Pd2+高活性物种的稳定。相比Pd/γ-Al2O3,La改性催化剂均降低了C3H8和NO的反应转化温度。选用不同La前驱体对催化活性影响存在差异的主要原因是La前驱体添加而引起的金属-载体相互作用和活性贵金属钯的分散状态变化。     

不同载体对甲醇分解钯催化剂性能的影响

用浸渍法制备了Pd/γ-Al2O3和Pd/Ce0.65Zr0.35O22种甲醇分解催化剂。采用XRD,NH3-TPD(NH3-Temperature-Programmed Desorption),XPS及H2-TPR(H2-Temperature-Programmed-Redution)等手段对2种催化剂的结构和性能进行表征,并考察了催化剂上甲醇低温分解的活性。结果表明,Pd/Ce0.65Zr0.35O2催化剂具有较弱的表面酸性及良好的低温还原性能;XPS结果表明2种催化剂中的Pd均以氧化态形式存在,并且Pd在Ce0.65Zr0.35O2固溶体上呈高度分散状态,Pd与Ce间具有较强的相互作用。结合活性考察可知,Pd+的存在有利于甲醇的分解。Pd/Ce0.65Zr0.35O2催化剂具有高的催化活性,220℃时甲醇转化率接近100%。     

Pt/Al2O3催化剂用于NO氧化的活化效应研究

柴油机氧化催化剂(DOC)能将尾气中部分NO氧化成NO_2,一定浓度的NO_2有利于柴油机颗粒捕集器(DPF)的连续再生和提高选择性催化还原催化剂(SCR)对NO_x的转化效率。针对DOC的新鲜态Pt/Al_2O_3 催化剂经过1次程序升温NO催化氧化活性明显提升的现象(活化效应),采用原位红外漫反射实验(in situ DRIFTS)、氢气程序升温还原、X射线光电子能谱(XPS)和高分辨透射电子显微镜(HR-TEM)分析Pt/Al_2O_3催化剂相关过程的物理化学状态。分析结果表明,新鲜态Pt/Al_2O_3催化剂在300℃以下时载体上积累了大量的硝酸盐和亚硝酸盐物种,导致新鲜态催化剂活性不高;进一步的分析表明经一次程序升温后催化剂中与载体结合强的PtO_x物种的分解是引起活化效应的主要原因;经过3次程序升温反应,催化剂中Pt粒子的大小没有发生明显改变。     

Pd/γ-Al2O3催化剂上甲烷-氘化氢之间的氢氘交换性能研究

利用浸渍法制备了Pd/γ-Al2O3催化剂,采用X射线粉末衍射(XRD)、X光电子能谱(XPS)和程序升温还原(TPR)等物理化学手段对其进行了表征,并在固定床微型反应器上考察了其催化活性。实验结果表明,载体内部有Pd元素,Pd和载体γ-Al2O3发生了强相互作用。在对甲烷与氘化氢间的氢氘交换反应中,Pd/γ-Al2O3催化剂显示出较好的催化活性。     

Ce改性ZSM-5分子筛载Pd催化剂的CeO2-Pd协同作用研究

采用XRF、XRD、SEM和CH4-TPR表征手段,研究了Ce改性ZSM-5分子筛载Pd催化剂在CO、CH4氧化过程中的CeO2-Pd协同作用。结果表明,经Ce改性后ZSM-5分子筛的载Pd量提高;Pd/Ce-ZSM-5催化剂对 CH4的起始吸附温度降低;Pd/Ce-ZSM-5催化剂中 Ce 主要以 CeO2形态存在。Pd是CO的催化氧化活性物种,CeO2-Pd协同作用可促进CO的氧化。Pd和PdO均是CH4的催化氧化活性物种,CeO2的供氧-储氧特性有助于Pd→PdO的转化,CeO2与Pd的相互作用使Pd/Ce-ZSM-5催化剂具有高的CO和CH4催化氧化活性。     

新鲜和老化Pd/Al_2O_3密偶催化剂上催化C_3H_8转化催化性能（英文）

采用等体积浸渍法制备了以改性氧化铝为载体材料的Pd/Al_2O_3密偶催化剂,并采用H_2程序升温还原(H_2-TPR),CO化学吸附和X射线光电子能谱(XPS)对催化剂进行了表征。在模拟尾气条件下对催化剂的总包反应及与C_3H_8相关的单反应活性进行了测试。结果表明,老化处理后活性PdO_x数量下降,并伴随有金属态Pd~0的产生。老化后,起燃温度(T_(50))和完全转化温度(T_(90))分别提高了76和64℃,即催化剂低温活性比高温活性下降明显。对比新鲜和老化催化剂上单反应活性,结果表明,老化后无水条件下有NO参与的反应的低温活性下降显著。老化处理过程突出了NO对低温活性的抑制作用和H_2O对高温活性的促进作用。     

预处理条件对Pt/Al2O3催化氧化NO性能的影响

考察了温度和反应气氛对新鲜态Pt/Al2O3催化剂上NO氧化过程中的degreening效应的影响。利用活性评价实验测试不同条件下NO氧化活性,用H2程序升温还原(H2-TPR)表征了degreening效应过程中催化剂中Pt的价态变化。在degreening效应过程中,新鲜态Pt/Al2O3催化剂中与载体结合较弱的PtOx物种在温度低于300℃时被NO还原为Pt⁰;与载体结合较强的PtOx物种在温度高于400℃时分解成Pt⁰。新鲜态Pt/Al2O3催化剂经过第一次程序升温反应后,NO氧化活性位Pt⁰的增加导致了其NO氧化能力提高。     

热轧退火态430不锈钢的高温抗氧化性能

研究了热轧退火态的430铁素体不锈钢在700~900℃的高温氧化行为,测量了其恒温氧化增重曲线,利用扫描电镜(SEM)和能谱仪(EDS)观察分析了氧化表面形貌和组成,使用X射线衍射仪(XRD)鉴定了氧化物的种类。结果表明:在700℃生成的Cr2O3氧化膜不足以覆盖基体,材料氧化缓慢;800℃时氧化速率相对较大,生成的氧化物主要为Cr Mn1.5O4和Fe2O3;900℃时氧化十分迅速,材料表面有大量Fe2O3突起;退火温度对材料高温氧化性能影响不大。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.