共查询到18条相似文献,搜索用时 93 毫秒
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采用化学浸渍法制备出Au/Co_3O_4纳米复合材料,用透射电子显微镜(TEM)、X射线能谱(EDS)和X射线粉末衍射(XRD)等对其结构和组成进行了表征,并考察了其在对硝基苯酚加氢反应中的催化性能。表征结果表明,Au纳米粒子很好地分散在Co_3O_4载体上。催化性能测试表明,Au/Co_3O_4纳米复合材料对于对硝基苯酚加氢反应表现出优异的催化活性,TOF值为5.01 min~(-1);此外,催化剂经过5次循环仍然保持优异的催化性能。 相似文献
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负载型纳米Au催化剂在许多还原反应中表现出良好的催化活性和选择性,是一类很有发展前景的选择性加氢催化剂。以侧柏叶提取液为还原Au(III)溶液的生物质,采用原位还原法制备了Au/Fe3O4催化剂,利用TEM、XRD、XPS等方法对催化剂进行了表征,以肉桂醛选择性加氢为模型反应,考察了催化剂的催化性能,并对肉桂醛选择性加氢的工艺条件进行优化,得到最佳制备条件为:Au负载量为1.0%,焙烧温度为200℃。最佳反应工艺条件为:反应温度60℃,反应压力5.0 MPa,催化剂用量为0.30 g,乙醇为溶剂。在此条件下反应3 h,肉桂醛的转化率为86.4%,肉桂醇的选择性为69.3%。 相似文献
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从载体的改性,包括载体的预处理、制备过程中加入特定元素;以及催化剂的制备,包括活性金属负载方法、浸渍过程中添加助剂等方面,综述了蒽醌法生产过氧化氢所采用的固定床和流化床两种工艺使用的加氢催化剂的研究进展。分析认为,对于普遍使用的钯载体催化剂,助剂对载体的改性和催化剂的制备优化具有显著的效果。固定床工艺近期仍将是国内双氧水生产的主要方式,加强助剂添加和活性金属替代钯的研究具有重要的意义。引进流化床工艺取代固定床工艺,增加单套装置产能是未来国内双氧水生产发展趋势,需加强催化剂的研究开发。 相似文献
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介绍了国内炭载催化剂中铂、钯、铑、钌化学分析技术的进展,对该类催化剂的制备过程及化学分析特点、试样的前处理、铂族金属含量的测定方法进行了评述,并对未来试样的前处理和提高电感耦合等离子体原子发射光谱法(ICP-AES)测定高量铂族金属的准确度、精密度技术进行了展望。 相似文献
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比较酸溶法消解催化剂中Pt、Pd、Rh的研究 总被引:1,自引:0,他引:1
实验比较研究了盐酸、硝酸、氢氟酸、高氯酸、硫酸等几种酸以一定的配比混合消解催化剂试样,采用光度法测定试样中贵金属Pt、Pd、Rh的含量。结果表明:采用聚四氟乙烯消化罐,试剂用HCl-HF-H2O2溶解催化剂试样,更利于Pt、Pd、Rh的溶出,Pt、Pd、Rh的回收率分别为99.5%、99.8%、101.6%,相对标准偏差分别为3.04%、2.71%、1.80%。结果满意,方法简便,容易操作。 相似文献
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Modeling the dislocation properties and mechanical behavior of Ir,Rh, and their refractory alloys 总被引:1,自引:0,他引:1
Oleg Y. Kontsevoi Yuri N. Gornostyrev Arthur J. Freeman 《JOM Journal of the Minerals, Metals and Materials Society》2005,57(3):43-47
While interest is growing in iridiumand rhodium-based refractory alloys as new materials for ultra-high-temperature applications,
very little is known about the fundamental factors controlling their mechanical properties. Experimental difficulties with
in-situ investigations of these alloys emphasize the need for theoretical modeling as an important tool for accelerated progress
in this field. This article presents results of an investigation of the brittle/ductile behavior and dislocation properties
in iridium, rhodium, and their L12 intermetallic alloys based on first-principles total energy calculations.
For more information, contact Oleg Y. Kontsevoi, Northwestern University, Department of Physics and Astronomy, 2145 N. Sheridan
Road, Room F251, Evanston, IL 60208-3112; (847) 491-8637; fax (847) 491-5082; e-mail ok@mars.phys.northwestern.edu. 相似文献
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The phase diagrams of the eight ternary systems Ag–La–Ni, Au–La–Ni, Ir–La–Ni, La–Ni–Os, La–Ni–Pd, La–Ni–Re, La–Ni–Rh and La–Ni–Ru have been investigated experimentally in the La-poor region. In each system, the ternary extension of the CaCu5 phase based on LaNi5 has been particularly well studied in order to measure the solubility limit of the third element. In most systems, the nature of the phases in equilibrium with the CaCu5 phase has been established and a partial phase diagram could be drawn. The structural properties (lattice parameters and substitution site(s) of the third element) of the ternary CaCu5 phase have been studied in detail. 相似文献
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汽车尾气净化催化剂中Pt、Pd、Rh含量的测定 总被引:7,自引:4,他引:7
试样在聚四氟乙烯压力罐内加HCl-H2 O2 于 1 50℃浸出 ,用吸光度法测定汽车催化剂中贵金属元素 (Pt、Pd、Rh )的含量。Pt、Pd用二苄基二硫代乙二酰胺 -碘化钾 -抗坏血酸体系双波长分光光度法同时测定 ;Rh用 2 -巯基苯并噻唑 -溴化亚锡萃取光度法测定。对 2种汽车催化剂 (陶瓷蜂窝状 )ATCTL - 1 (新 )和ATCTL -GM (废 )测得Pt、Pd、Rh含量分别为 :Pt 979± 5 5μg/g和 964± 6 8μg/g ;Pd 1 68± 2 5μg/g和 1 65± 6 0 μg/g ;Rh 1 0 6± 1 8μg/g和 1 0 4± 2 6μg/g 相似文献
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Lattice constants, total energies, and densities of state of transition metals Co, Rh, and Ir in the VIIIB group with different
crystalline structures were calculated via generalized gradient approximation (GGA) of thetotal energy plane wave pseudopotential
method in first-principles. The lattice stabilities of Rh and Ir are ΔG
bcc-hcp > ΔG
fcc-hcp > 0, agreeing well with those of the projector augmented wave method in first-principles and the CALPHAD method in spite
of elemental Co. Analyses of the electronic structures to lattice stability show that crystalline Rh and Ir with fcc structures
have the obvious characteristic of a stable phase, agreeing with the results of total energy calculations. Analyses of atomic
populations show that the transition rate of electrons from the s state to the p or d state for hcp, fcc, and bcc crystals
of Co and Rh increases with the elemental period number to form a stronger cohesion, a higher cohesive energy, or a more stable
lattice between atoms in heavier metals. 相似文献
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采用密闭消解的方法,以王水在200℃经16 h消解地质样品,用电感耦合等离子体质谱法(ICP-MS)直接测定Rh和Ir。以Lu为内标元素消除基体效应,建立校正方程消除Cu和Sr对Rh、Hf对Ir的所产生的多原子离子干扰,可在酸溶体系中不经分离富集直接测定铂族物料中的痕量Rh和Ir。结果表明,Rh和Ir的检出限分别为0.014 ng/g和0.012 ng/g,方法回收率为90%~111%,用于铂族元素地球化学一级标准物质中Rh、Ir的测定,所得结果与认定值一致,相对标准偏差(RSD)小于9.6%。 相似文献