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1.
用溶胶 凝胶法以磷钼酸 (MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2 催化剂 .使用ICP、XRD、TG DTA、IR、TPD MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能 .杂多钼酸盐与TiO2 通过O2 -在TiO2 表面发生了键合 .在 6 2 3K下 ,杂多阴离子仍保持原有的Keggin结构 .CO2 在Lewis酸位Ni(Ⅱ )和Lewis碱位Ni-O -Mo的桥氧协同作用下生成CO2 卧式吸附态Ni(Ⅱ )←O - (CO)← (O--Ni) .丙烯有多种吸附态在催化剂上吸附 .在 5 6 3K、1MPa和空速 15 0 0h-1的反应条件下 ,丙烯的摩尔转化率为 3.2 % ,产物MAA选择性为 95 % . 相似文献
2.
Kateina Syslová Pavel imanec Josef Tichy 《Reaction Kinetics and Catalysis Letters》2005,87(1):165-169
Summary The oxidative dehydrogenation of crotonaldehyde to furan and maleic anhydride was carried out over K2HPMo12O40catalyst. A positive effect of water vapor on furan formation is explained by ability of the catalyst to isomerize 2E- to
2Z-crotonaldehyde.</o:p> 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的铜盐溶液水解钛酸四丁酯制备了CuPMo/TiO2催化剂,并用ICP,XRD,TG-DTA,IR,TPD-MS和微反技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化性能.结果表明:杂多钼酸盐与TiO2表面通过O2-桥发生键联.在623K下,杂多阴离子仍保持其原有的Keggin结构;CO2在Lewis酸位Cu(Ⅱ)和Lewis碱位Cu-O-Mo桥氧的协同作用下形成卧式吸附态Cu(Ⅱ)←O-(CO)←(O--Cu);丙烯以分子吸附态在催化剂上吸附;在空速1500h-1,压力1MPa和温度563K的反应条件下,丙烯的转化率为4.2%,甲基丙烯酸的选择性为96%. 相似文献
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The swelling properties of Al-pillared clays, obtained from five different smectites, were studied using X-ray diffraction. These clays, the dioctahedral beidellite and montmorillonite and the trioctahedral saponite, hectorite and laponite differ in source of isomorphic substitution and represent a series of decreasing basicity along the siloxane plane. An Al oxyhydroxy cation was inserted between the layers to form the respective pillared clays and these clays were heated incrementally to 600°C. The XRD peaks at each stage of heating were recorded as well as the same samples subsequently wetted. Basal spacings of each clay at each stage of dehydration d rehydration indicated that the swelling of tetrahedrally substituted saponite and beidellite was indeed restricted, compared with the other three clays. This was attributed to greater basicity of the oxygen plane of beidellite and saponite due to tetrahedral substitution of Si by Al, resulting in an increase in the strength of hydrogen bonds between either water or the interlayer polyhydroxy cation and the clay.The data from the XRD analyses helped in addition, to clarify the thermal transformations of the Keggin ion itself. According to the changes in thed-spacings of the pillared clays it was concluded that the Keggin ion lost its structural water at 200°C and dehydroxylated in a range beginning at 350°C. Between 500 to 600°C this polymer cation, which is thought to form the Al2O3 oxide, did not rehydrate.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThe authors wish to thank Laporte Industries, Inc., U.K. for the laponite sample. 相似文献
7.
两种结构钼磷酸的催化氧化行为 总被引:11,自引:0,他引:11
考察了Dawson与Keggin结构钼磷酸的催化氧化行为,并与结构特性进行了关联,结果发现,Dawson结构的杂多酸对氧化脱氢及插入氧反应均有更高的活性。 相似文献
8.
本文以气相色谱为主要手段,配合红外光谱、X—射线粉末衍射分析及电子顺磁共振技术,研究了十二钼磷酸及其盐在氢气中的还原热稳定性。从对上述化合物在氢气中热解过程的气相产物和各中间固相产物的分析可知,在实验的温度范围内(40~640℃),这些化合物的热分解过程通常分为三或四个阶段。实验发现,Keggin阴离子热解以及Mo~(6 )被还原的难易程度,取决于与Keggin阴离子结合的阳离子的种类。在同一实验条件下,如果阳离子本身难以还原,那么,Keggin阴离子的破坏以及Keggin阴离子中Mo~(6 )还原为金属相的过程,都将变得困难。 相似文献
9.
A novel hybrid tungstocuprate(Ⅱ) [Cu(2,2'-bpy)3]2H4[CuW12O40]·6H2O(2,2'-bpy=2,2'-bipyridine) was synthesized via hydrothermal method and characterized using elemental analyses, IR, UV, XPS, TG-DSC, EPR, and X-ray single crystal diffraction. The structural analysis shows that the complex consists of an unusual Keggin-type polyoxoanion [CuW12O40]6- and a pair of chiral complex cations [Cu(2,2'-bpy)3] together with four protons and six crystallization water molecules, and the Keggin polyoxoanion is connected with [Cu(2,2'-bpy)3] via multiple C-H…O hydrogen bonds resulting in a dimer. 相似文献
10.
Reduced Clusters with Remarkable Topological and Electronic Properties of the Type of [V18O42(X)]n? (X = SO4, VO4) with Td-Symmetry and Related Clusters [V(18—p)As2pO42(X)]m? (X = SO3, SO4, H2O; p = 3, 4) The novel cluster-compounds Na6[V18O42H9(VO4)] · 21 H2O, (NH4)8[V18O42(SO4)] · 25 H2O, K6[V15As6O42(H2O)] · 8 H2O, (NH4)6[V14As8O42(SO3)], (NH4)6[V14As8O42(SO4)] and [N(CH3)3]4[4V14As8042(H20)] were prepared and characterized by IR- and UV/Vis/NIR-spectroscopy, magnetic measurements and complete crystal structure analysis. For structural data see Inhaltsübersicht. Topological relations to the rhombicuboctahedron spanned by 24 0-atoms of the genuine hypothetical a-Keggin ion, at which the square planes are capped by V?O or As2O groups, are discussed. Of particular interest are the ?extended”? Keggin ions [V18O42(X)]n- (X = SO4 VO4), (formaly derived from the hypothetical genuine a-Keggin ion by addition of six V?O groups) which have quite different electron populations in spite of the same structure of their cluster shells. 相似文献