| 负载钨催化剂的载体效应及其表面酸性 |
| THE SUPPORT EFFECT AND SURFACE ACIDITY OF THE SUPPORTED TUNGSTEN OXIDE CATALYSTS BY USING ZIRCONIUM HYDROXIDE AND OXIDE SUPPORTS |
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| 摘要: 运用BET、XRD、FT-Raman以及微量吸附量热等手段对由浸渍三种晶型氧化锆及其前体氢氧化锆制备的负载钨催化剂的结构及其表面酸性进行了研究。结果表明起始原料和制备条件对氧化锆的结构有显著影响。浸渍在氢氧化锆上的钨物种会使氢氧化锆转变为四方晶型氧化锆。但浸渍于氧化锆上的钨物种使氧化锆发生晶型转变相对较难。负载钨催化剂表面强酸位的形成与载体晶型、表面钨物种WOx以及WOx与载体氧化锆之间的相互作用有关。催化剂上的强酸位可因残留的Na+离子所毒化或阻抑。少量Y3+离子对表面酸性则无明显影响。 |
| 关键词: 氧化锆 负载钨催化剂 载体效应 表面酸性 |
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| Abstract: The structure and surface acidity of zirconia supported tungsten oxide are studied by using BET, XRD, FT Raman, Tian-Calvet microcalorimetry et al. Three different types of ZrO2 and their hydroxide precursors can be obtained in a controllable way. The starting material and the different preparing conditions are able to affect considerably the final ZrO2 structure. The zirconium hydroxide supported tungsten species will promote the transformation of different kinds of hydroxides into tetragonal ZrO2. Such effect, however, is difficult to occur on the ZrO2 supported systems. The structures of impregnated surface tungstates on three zirconium hydroxide precursors or three types of zirconia are similar. Before calcination, the structural differences in the surface tungstates between hydroxide precursor and oxide supported samples are insignificant. After heat treatment, however, considerable alterations occurred in the structures of tungsten species on the two series samples. The tungsten components in the calcined samples are the surface tungsten oxides together with the crystalline WO3. The ratio of the two species is affected by the preparation history and the nature of support. Generation of strong acidic sites will be dependent on the crystal structure of ZrO2 phase, the type of tungsten oxide species and the cooperation between the surface tungsten oxide overlayer and ZrO2. Remaining sodium ion impurities can prohibit creation of strong acidic sites or directly poison these sites, introduce of yttrium component into zirconium oxide, however, has not shown appreciable effect on the surface acidity. |
| Keywords: zirconium oxide structure supported tungsten oxide catalysts support effect surface acidity |
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| 摘要点击次数: 1574 |
| 全文下载次数: 1797 |
| 曾翎,季伟捷,陈懿.负载钨催化剂的载体效应及其表面酸性[J].无机化学学报,1999,15(4):475-481. |
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