共查询到20条相似文献,搜索用时 156 毫秒
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稀土水滑石的合成与表征(Ⅰ) 总被引:11,自引:2,他引:11
合成了稀土镧在层晶格骨架中的水滑石,经粉末X射线衍射、红外光谱、X射线光电子能谱及离子交换法进行了表征.通过催化苯酐与正己醇的酯化反应,表明样品具有催化活性. 相似文献
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ZnO/HZSM-5丙烷芳构化催化剂中锌的形态表征 总被引:3,自引:0,他引:3
用机械混合法制备了ZnO/HZSM-5丙烷芳构化催化剂.X射线衍射与透射电镜测试结果表明,沸石表面的ZnO在焙烧后发生了分散和迁移.稀盐酸对沸石表面锌的反交换实验结果表明,有部分锌迁入沸石孔道并与沸石表面发生了相互作用.用X射线光电子能谱和吡啶吸附的红外光谱技术对ZnO/HZSM-5进行了表征,结果进一步表明有部分ZnO与HZSM-5发生固相离子交换反应.对HZSM-5和ZnO/HZSM-5催化剂的丙烷芳构化活性进行了评价,讨论了锌物种在丙烷芳构化反应中的作用. 相似文献
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应用Y分子筛吸附Fe(CO)5、Co(CO)3NO和Mo(CO)6的温和热分解制备分子筛负载金属催化剂,从分子筛交换阳离子和吸附金属络合物之间的相互作用说明其CO加氢产物的分布特点。实验结果表明,分子筛内阳离子和吸附金属络合物间的相互作用显著影响制得催化剂的结构和反应的产物分布。由于金属络合物和分子筛内阳离子间的电子转移,使NiY附载金属催化剂显示出高的CO转化率和甲烷选择性。在CuY中,这种电子 相似文献
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以γ-Al_2O_3为载体,用浸渍法负载碱金属和碱土金属氧化物制备了一系列羰基硫水解催化剂。采用微反-色谱联用装置考察了45—100℃低温区内的活性变化规律。结果表明,催化剂活性与金属氧化物组分及含量有着密切关系。在考察各催化剂在不同温度下水解反应速度常数(K)的变化中,发现指前因子(A)与活化能(E)之间存在着补偿效应,活化能增大时指前因子也随之增大。补偿效应参数(K_0)和能量分布指前因子(1/b)均与负载的金属离子半径(d_m)有关。求得了各催化剂的等动力学温度(T),讨论了羰基硫水解反应中存在补偿效应的原因。 相似文献
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Min Hye Youn Jeong Gil Seo Ji Chul Jung Jin Suk Chung In Kyu Song 《Catalysis Surveys from Asia》2010,14(2):55-63
Recent progress on support modification of supported nickel catalysts for hydrogen production by auto-thermal reforming of
ethanol was reported in this review. Nickel catalysts supported on various materials, including metal oxides and metal oxide-stabilized
mesoporous zirconias, were prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal
reforming of ethanol. Various experimental measurements such as NH3-TPD (temperature-programmed desorption) and TPR (temperature-programmed reduction) were carried out to elucidate the different
catalytic performance of supported nickel catalysts. It was revealed that acid property of supporting materials served as
one of the important factors determining the catalytic performance. Hydrogen yield over nickel catalysts supported on metal
oxides showed a volcano-shaped curve with respect to acidity of the supports. Among the catalysts tested, Ni/ZrO2 catalyst with an intermediate acidity exhibited a superior catalytic performance. It was also observed that reducibility
of nickel catalysts supported on metal oxide-stabilized mesoporous zirconias played a key role in determining the catalytic
performance in the auto-thermal reforming of ethanol for hydrogen production. Hydrogen yield over nickel catalysts supported
on metal oxide-stabilized zirconias increased with increasing reducibility of the catalysts (with decreasing TPR peak temperature
of the catalysts). 相似文献
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含有双配位基的聚苯乙烯邻氨基苯甲酸与钯络合物反应制得螫合的配位高分子钯催化剂。用甲醇-水(pH=12)还原可得晶粒分布均匀的胶态钯催化剂,它们对烯烃的加氢具有良好的催化作用。研究表明,钯络合物上原有配体的给予性常数(E_n)与负载后络合催化剂的加氢活性具有良好的线性关系,金属粒径为40—50A的催化剂对己烯-1的加氢活性最高。本文还研究了溶剂极性,载体孔结构及底物对催化剂活性的影响。 相似文献
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SMAI和CI法制备的Ni—Ag/SiO2催化剂的结构与催化性质研究 总被引:1,自引:0,他引:1
应用溶剂化金属原子浸渍(SMAI)法和普通浸渍(CI)法制备了金属含量相同的SiO2负载Ni-Ag双金属催化剂。XRD和磁测定结果表明SMAI催化剂中Ni和Ag的粒度均小于金属含量相同的CI催化剂,SMAI催化剂中Ni和Ag未形成合金,而CI催化剂中Ni和Ag形成了合金。SMAI和CI催化剂都具有超顺磁性。研究了这些催化剂在甲苯加氢反应的催化性质,结果表明与组成相同的普通浸渍法催化相比,SMAI催 相似文献
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Slagt VF Kamer PC van Leeuwen PW Reek JN 《Journal of the American Chemical Society》2004,126(5):1526-1536
Encapsulated transition metal catalysts are presented that are formed by templated self-assembly processes of simple building blocks such as porphyrins and pyridylphosphine and phosphite ligands, using selective metal-ligand interactions. These ligand assemblies coordinate to transition metals, leading to a new class of transition metal catalysts. The assembled catalyst systems were characterized using NMR and UV-vis spectroscopy and were identified under catalytic conditions using high-pressure infrared spectroscopy. Tris-3-pyridylphosphine binds three mesophenyl zinc(II) porphyrin units and consequently forms an assembly with the phosphorus donor atom completely encapsulated. The encapsulated phosphines lead exclusively to monoligated transition metal complexes, and in the rhodium-catalyzed hydroformylation of 1-octene the encapsulation of the catalysts resulted in a 10-fold increase in activity. In addition, the branched aldehyde was formed preferentially (l/b = 0.6), a selectivity that is highly unusual for this substrate, which is attributed to the encapsulation of the transition metal catalysts. An encapsulated rhodium catalyst based on ruthenium(II) porphyrins and tris-meta-pyridyl phosphine resulted in an even larger selectivity for the branched product (l/b = 0.4). These encapsulated catalysts can be prepared easily, and various template ligands and porphyrins, such as tris-3-pyridyl phosphite and ruthenium(II) porphyrins, have been explored, leading to catalysts with different properties. 相似文献
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The partial oxidation of methane to formaldehyde was studied over different silica-supported metal oxide catalysts. The results show thatMoO3/SiO2 is the most selective catalyst among those studied, P2O5 exhibit a Promoting effect to the silica supported transition metal oxide catalysts for the formation of formaldehyde and a small amount of MoO3 can improve the selective properties of these catalysts. 相似文献
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