The influence of surface composition of Ag3PW12O40 and Ag3PMo12O40 salts on their catalytic activity in dehydration of ethanol
The influence of surface composition of Ag3PW12O40 and Ag3PMo12O40 salts on their catalytic activity in dehydration of ethanol
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DOI：
10.1016/j.molcata.2011.09.016
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发表时间：
2011-12-01
影响因子：
--
通讯作者：
Matachowski, L.
中科院分区：
文献类型：
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作者：
Gurgul, J.;Zimowska, M.;Matachowski, L.
本工作的目的是研究空气相对湿度对 Ag3PW12O40 和 Ag3PMo12O40 盐在乙醇气相脱水中催化活性的影响。该反应在相对湿度为2%或9%的空气中和373-493 K的温度范围内进行。Ag3PW12O40盐的催化活性远高于Ag3PMo12O40盐的催化活性，并且强烈依赖于空气的相对湿度。 XRD 测量表明，Ag3PW12O40 盐的结构在 473-573 K 范围内失去水合银，而 Ag3PMo12O40 盐在 373-473 K 范围内失去水合银。 FT-IR 光谱表明反应后 Ag3PW12O40 盐的 Keggin 结构的稳定性，与空气的相对湿度无关。然而，XPS 光谱显示该盐在相对湿度为 2% 的空气中反应后表面成分发生变化，而 SEM 成像显示其表面形成了银纳米结构。 Ag3PW12O40盐在相对湿度9%的空气中反应后保持稳定。对于在乙醇脱水前后分析的 Ag3PMo12O40 盐，XPS 发现表面成分的差异非常有限，并得到 SEM 成像的支持。 (C) 2011 Elsevier B.V. 保留所有权利。
The aim of this work was to investigate the influence of relative humidity of air on the catalytic activity of Ag3PW12O40 and Ag3PMo12O40 salts in the vapor-phase dehydration of ethanol. The reaction was performed in air of relative humidity of 2% or 9% and in the temperature range of 373-493 K. The catalytic activity of Ag3PW12O40 salt was much higher than the one obtained for Ag3PMo12O40 salt and strongly dependent on relative humidity of air. The XRD measurements showed that the structure of Ag3PW12O40 salt loses the water hydrating silver in the range of 473-573 K whereas Ag3PMo12O40 salt in 373-473 K. The FT-IR spectra demonstrated the stability of Keggin structure of Ag3PW12O40 salt after reaction, independently of relative humidity of air. However, the XPS spectroscopy exhibited the changes in surface composition of this salt after reaction in air of 2% of relative humidity whereas the SEM imaging displayed the formation of silver nanostructures on its surface. The Ag3PW12O40 salt remained stable after reaction in air of 9% of relative humidity. In case of Ag3PMo12O40 salt analyzed before and after ethanol dehydration, a very limited difference in surface composition was found by XPS that was supported by SEM imaging. (C) 2011 Elsevier B.V. All rights reserved.