共查询到19条相似文献,搜索用时 125 毫秒
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采用表面改性和离子交换相结合的方法制备了Ni2 (OCH3 ) 2 /SiO2 负载型双核金属甲氧基配合物催化剂 ,利用红外光谱 (IR)、程序升温脱附 (TPD)、程序升温表面反应 (TPSR)和微反技术考察了催化剂的表面结构以及CO2 和CH3 OH的化学吸附和反应性能 .结果表明 :Ni2 (OCH3 ) 2 /SiO2 中Ni2 + 与载体SiO2 表面O2 -以双齿配位形式键合 ,甲氧基以桥基形式联结双金属离子形成双核物种Ni2 (OCH3 ) 2 ;CO2 在催化剂表面存在甲氧碳酸酯基物种和桥式两种吸附态 ,CH3 OH则只有一种分子吸附态 ;在 10 0~ 2 0 0℃条件下 ,CO2 和CH3 OH在催化剂上的反应产物主要是DMC和H2 O ;根据反应结果 ,讨论了催化反应机理 . 相似文献
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采用离子交换法在不同煅烧温度下制备HMOR负载Cu(Cu/HMOR)催化剂,用于催化二甲醚(DME)羰基化合成乙酸甲酯(MA)反应. 活性测试结果表明430 oC煅烧制得Cu/HMOR具有较好催化活性,在210 oC、1.5 MPa、空速4883 h-1下DME转化率为97.2%,MA选择性为97.9%. 对催化剂进行X射线衍射、N2物理吸附、NH3程序升温脱附、CO程序升温脱附及拉曼方法表征. 催化剂经一定的煅烧温度有利于Cu离子迁移及扩散和硝酸铜完全分解,从而使HMOR载体具有较多的酸性活性位、大比表面、适宜的微孔结构以及更多的CO吸附位. 相似文献
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Ni2(OCH3)2/SiO2催化剂上C02和CH30H的吸附和反应性能 总被引:2,自引:1,他引:1
采用表面改性和离子交换相结合的方法制备了Ni2(OCH3)2/Si02负载型双核金属甲氧基配合物催化剂,利用红外光谱(IR)、程序升温脱附(TPD)、程序升温表面反应(TPSR)和微反技术考察了催化剂的表面结构以及C02和CH30H的化学吸附和反应性能.结果表明:Ni2(OCH3)2/SiO2中Ni^2+与载体SiO2表面O^2-以双齿配位形式键合,甲氧基以桥基形式联结双金属离子形成双核物种Ni2(OCH3)2;CO2在催化剂表面存在甲氧碳酸酚基物种和桥式两种吸附态,CH30H则只有一种分子吸附态;在100—200℃条件下,C02和CH30H在催化剂上的反应产物主要是DMC和H20;根据反应结果,讨论了催化反应机理. 相似文献
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采用超声处理辅助浸渍法制备了多壁碳纳米管负载的Cu-Co复合氧化物催化剂. 利用XRD、TEM、H2-TPR、XPS和Raman光谱等表征了催化剂的结构性质. 在Cu和Co氧化物以及金属氧化物与碳纳米管载体间存在强相互作用. 催化剂在富氢气氛中CO催化消除反应中,与单一Cu或Co催化剂相比,Cu-Co复合氧化物催化剂表现出独特的反应特性,特别是在较高反应温度下可同时结合CO优先氧化和CO甲烷化的反应途径来实现高效CO消除. 当Cu/Co比为1/8时活性最优,可以实现在150~250 o和高反应空速 (120 L/(h·g))富氢气氛中CO的完全消除. 相似文献
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本文针对Sm3Co粗晶和纳米晶合金材料的制备和基础性能进行了研究.采用磁悬浮熔炼技术多次精炼制备出Sm3Co粗晶合金.以此为母材,利用高能球磨非晶化和放电等离子烧结致密化并同步晶化的技术路线,制备出平均晶粒尺寸为8 nm的超细纳米晶Sm3Co合金块体材料.构建了Sm3Co纳米晶合金的晶体结构模型,并结合其显微组织的表征,分析了Sm3Co纳米晶合金的磁性能和力学性能,并与粗晶合金进行了比较粗晶Sm3Co合金不具有硬磁特性,而同种成分的纳米晶合金则表现出一定的硬磁特性.纳米晶Sm3Co合金的显微硬度和弹性模量分别达到4.87 GPa和63.7 GPa,比粗晶合金增大约8.7%和13.3%.本文研究结果为Sm-Co体系合金的基础性能及其纳米尺度效应提供了系统的参考依据. 相似文献
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用水热法得到的钛酸纳米纤维前体,通过不同后处理方法合成了多种纳米结构的TiO2.采用N2等温吸附和BET比表面、X射线衍射、透射电镜和能量分散X射线分析表征了TiO2及负载Ru催化剂的微结构,包括比表面、晶相结构和形貌以及Ru纳米颗粒尺寸分布等.对负载Ru催化剂在富氢条件下CO选择甲烷化反应活性测试表明:金红石相TiO2和TiO2-B为载体负载的Ru催化剂比锐钛矿相TiO2负载的Ru催化剂表现出更高的反应性能.其活性区别说明了不同晶相结构和形貌TiO2载体与Ru纳米颗粒的相互作用存在差异. 相似文献
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用脉冲激光沉积技术(PLD)在MgO(100)基底上生长了嵌埋Co纳米晶的BaTiO3复合薄膜. 分别利用x射线衍射(XRD)、原子力显微镜(AFM)以及拉曼光谱(Raman)对薄膜的微观结构、表面 形貌进行了表征. 结果表明该薄膜为c轴取向的四方晶体结构,薄膜表面均匀、致密、 具有原子尺度的光滑性,其均方根表面粗糙度(RMS)达到015nmCo以纳米晶形式嵌埋BaTi O3基体中,呈单分散性均匀分布,其粒径随激光脉冲数的增加而增大. Co:BaTiO3纳米 复合薄膜拉曼峰的强度随钴纳米晶粒径的增加明显减弱,但是峰的宽度逐渐增加.
关键词:
Co:BaTiO3
纳米复合薄膜
脉冲激光沉积 相似文献
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The possibility of forming surface films with an elevated concentration of an impurity metal during high-temperature diffusion has been analyzed for a wide series of ionic crystals: LiF with Co, Ni, Mg, Ca, Ba, and Sr impurities; NaF with Co, Mn, Mg, Ca, and Sr; MgF2 with Co and Ni; and CaF2 with Co. It is established that films are formed only on alkali halide crystals with impurities of transition metals and are not formed on alkaline earth fluorides with transition metals, as well as on alkali halide crystals activated with other divalent cationic impurities. The dynamics of the increase and decrease in the intensity of centers related to impurity-vacancy dipoles during thermal diffusion is shown. The mechanisms of film formation are explained in terms of the features of growth and structure of ionic crystals with cationic impurities and on the basis of isomorphism rules. 相似文献
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L. I. Bryukvina E. A. Ermolaeva S. N. Pidgurskiĭ L. F. Suvorova V. M. Khulugurov 《Physics of the Solid State》2006,48(1):68-72
It was detected for the first time that films consisting of a transition-metal-based structure form (via thermal diffusion
of intracrystalline impurities) on the surface of alkali-halide (LiF, NaF) crystals activated by transition metals Co, Ni,
or Mn. The thickness, density, and composition of the films are shown to be different, depending on the heat treatment conditions.
The crystals were annealed at temperatures varying from 473 to 1073 K in vacuum and air. The surface structures forming upon
annealing in vacuum exhibit magnetic properties. The films were studied by optical, x-ray fluorescence, and electron spectroscopy
to reveal the mechanisms of transition-metal film formation during thermal annealing. 相似文献
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过渡金属氧化物催化剂上NH3 分解Claus反应机理研究 总被引:3,自引:0,他引:3
运用浸渍法制备了七种过渡金属氧化物催化剂 .对于NH3 分解反应均可获得很高的NH3 转化率 ;对于NH3 分解Claus反应则可以获得较高的SO2 转化率和单质硫选择性 .通过比较发现Co3 O4 TiO2 和Fe2 O3 TiO2 催化剂的低温活性比较高 .经过XRD表征发现 ,在NH3 分解Claus反应中 ,催化剂的活性相可能是过渡金属硫化物 .结合活性评价和XRD表征结果提出了NH3 分解Claus反应的机理 . 相似文献
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锂离子电池以其高能量存储密度和优良的循环性能而受到广泛关注, 尤其是其正极材料成为储能材料领域的研究热点.本文采用基于密度泛函理论的第一性原理方法对LiCoO2,LiNiO2和Li(Co0.5Ni0.5)O2化合物的晶体结构、电子结构、化学键合特性进行了研究. 结果表明:Li(Co0.5Ni0.5)O2化合物中主要是氧和过渡金属之间成键, 锂原子对晶体总态密度贡献很少. Ni/Co混合后将导致Li(Co0.5Ni0.5)O2中Co的3d轨道和O的2p轨道之间成键得以加强. 相似文献
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Wenkai Zhao Dongqing Zou Zhaopeng Sun Yongjiang Yu Chuanlu Yang 《Physics letters. A》2018,382(37):2666-2672
Employing Green's function (GF) technique in combination with spin-polarized density functional theory (DFT), we study the electronic structure and magnetic properties of metal phthalocyanine (MPc) (M?=?Mn, Fe, Co, Ni, Cu, Zn) with or without four different gas molecules (NO, CO, O2 and NO2) adsorbing on the M atom of MPc molecule. The corresponding stable adsorption structural configurations and transport properties of MPc molecular junctions are also investigated. Our results indicate that the magnetic moment of MPc for M?=?Mn, Fe and Co can be modified by the specific gas molecule adsorption, which is mainly ascribed to competitive relation of HOMO-LUMO Gap and Hund's rules. However, for M?=?Ni, Cu and Zn, it is difficult to detect gas molecule because the interaction of M atom and these gases is most of weak van der Waals interaction. Remarkably, the spin of MPc molecule can be switched to a magnetic off-state by specific gas absorption, giving rise to a potential application on controllable spintronic devices. In addition, CO, NO, O2 and NO2 gas molecules can be detected selectively by measuring spin filter efficiency of these MPc molecular junctions. On the basis of our results, MPc (M?=?Mn, Fe, Co) molecular junctions can be considered as a promising nanosensor device to detect individual gas molecules. 相似文献
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锂离子电池以其高能量存储密度和优良的循环性能而受到广泛关注, 尤其是其正极材料成为储能材料领域的研究热点.本文采用基于密度泛函理论的第一性原理方法对LiCoO2,LiNiO2和Li(Co0.5Ni0.5)O2化合物的晶体结构、电子结构、化学键合特性进行了研究. 结果表明:Li(Co0.5Ni0.5)O2化合物中主要是氧和过渡金属之间成键, 锂原子对晶体总态密度贡献很少. Ni/Co混合后将导致Li(Co0.5Ni0.5)O2中Co的3d轨道和O的2p轨道之间成键得以加强. 相似文献
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通过共沉淀法, 在低温下制备了铜铁复合氧化物CuO/Fe2O3和铜钴复合氧化物CuO/Co3O4.利用GC微反应器评价了这些复合氧化物的催化活性和热稳定性,结果表明, CuO/Fe2O3和CuO/Co3O4的NO100%转化温度分别为80和90 ℃,该催化活性和热稳定性在较宽的温度和较长的时间范围内都能得以保持.此外,还系统研究了试剂的摩尔比率、NaOH的体积、陈化时间、煅烧温度和煅烧时间对该复合氧化物催化活性的影响. 相似文献
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Preparation of stable porous nickel and cobalt oxides using simple inorganic precursor, instead of alkoxides, by a sonochemical technique 总被引:3,自引:0,他引:3
Srivastava DN Pol VG Palchik O Zhang L Yu JC Gedanken A 《Ultrasonics sonochemistry》2005,12(3):205-212
Porous nickel and cobalt oxides were prepared using NiSO4.6H2O and anhydrous Co(CH3COO)2, a precursor other than alkoxides and cetyltrimethylammonium bromide as organic surfactant. The sonication method has been used for such synthesis. The surfactants were removed by calcination, as well as by solvent extraction and it is extent was examined by IR spectroscopy. The trend of removal of surfactant was followed by TGA studies and the change in phases by DSC. The products were identified by XRD. Peak in low angle XRD indicates the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. The pores were found less ordered, having an average size of 4-6 nm. The Brunauer-Emmet-Teller surface areas of the as-prepared, as well as the treated samples are reported having H2 and H4 type hysteresis for Ni and Co, respectively. 相似文献
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R. Szymczak C.P. Adams S.N. Barilo J.P. Clancy J. Fink-Finowicki M. Ramazanoglu Z. Yamani 《Journal of magnetism and magnetic materials》2009,321(7):793-795
This paper reviews experimental results concerning magnetic anisotropy in geometrically frustrated kagome staircase lattices. Following problems are discussed: high-temperature susceptibility measurements of kagome single crystals; inelastic neutron scattering measurements on Co3V2O8 single crystals; EPR of Co2+ ions in kagome staircase Mg3V2O8 single crystals. The single-ion anisotropy Hamiltonian is used to analyze experimental results. It is suggested that the magnetic anisotropy in kagome staircase M3V2O8 (M=Co, Ni, Mn) oxides has mainly single-ion origin. 相似文献