Pt dispersion control in Pt/SiO2 by calcination temperature using chloroplatinic acid as catalyst precursor
Pt dispersion control in Pt/SiO2 by calcination temperature using chloroplatinic acid as catalyst precursor
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DOI：
10.1016/j.apcata.2012.03.033
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发表时间：
2012-06-15
影响因子：
5.5
通讯作者：
Miura, Hiroshi
中科院分区：
文献类型：
--
作者：
Kaneko, Shinji;Izuka, Miyuki;Miura, Hiroshi
研究了预处理条件对Pt/SiO2分散性的影响。催化剂的制备是通过浸渍与H-2 PtCl 6作为Pt前体。将负载型Pt前体在氢气流中的直接还原与前体在空气流中在各种温度下煅烧，然后在氢气流中还原进行比较。当负载前体在氢气流中直接还原时，Pt分散与还原温度无关。与此相反，当负载前体煅烧，然后还原，Pt分散不受还原温度的影响，但在很大程度上取决于煅烧温度，范围广泛，从7至70%。一个很好的相关性被认为是从CO吸附计算的颗粒尺寸和透射电子显微镜观察。此外，发现在PtCl 2稳定的温度下煅烧得到最高的Pt分散。煅烧样品的X射线荧光分析证实了PtCl 2的形成。在最佳温度下煅烧后的高Pt分散度也用X-射线衍射分析证实，没有尖锐的衍射峰。结果表明，PtCl 2的迅速形成和再分散导致高Pt分散。(C)2012爱思唯尔有限公司版权所有。
The effect of pretreatment conditions on the dispersion of Pt/SiO2 was studied. The catalysts were prepared by impregnation with H-2 PtCl6 as the Pt precursor. Direct reduction of the supported Pt precursor in hydrogen flow was compared to calcinations of the precursor in air flow at various temperatures followed by reduction in hydrogen flow. When the supported precursor was directly reduced in hydrogen flow, Pt dispersion was independent of the reduction temperature. In contrast, when the supported precursor was calcined and then reduced, Pt dispersion was not affected by the reduction temperature but depended heavily on the calcination temperature, ranging widely from 7 to 70%. A good correlation was seen between the particle size calculated from CO adsorption and that observed with transmission electron microscope. Furthermore, it was found that calcination at the temperature at which PtCl2 is stable gives the highest Pt dispersion. X-ray fluorescence analysis of the calcined samples confirmed the formation of PtCl2. High Pt dispersion after calcination at optimum temperature was also corroborated with X-ray diffraction analysis from the absence of sharp diffraction peaks. The results suggest that prompt formation and redispersion of PtCl2 caused high Pt dispersion. (C) 2012 Elsevier B.V. All rights reserved.