物理化学学报 >> 2010, Vol. 26 >> Issue (04): 921-926.doi: 10.3866/PKU.WHXB20100446

催化和表面结构 上一篇    下一篇

钾对镁铝水滑石复合氧化物的表面改性

张业新, 苏庆运, 王仲鹏, 高希彦, 张昭良   

  1. 大连理工大学内燃机研究所, 辽宁 大连 116024; 济南大学化学化工学院, 济南 250022
  • 收稿日期:2009-11-19 修回日期:2010-02-26 发布日期:2010-04-02
  • 通讯作者: 张昭良 E-mail:chm_zhangzl@ujn.edu.cn

Surface Modification of Mg-Al Hydrotalcite Mixed Oxides with Potassium

ZHANG Ye-Xin, SU Qing-Yun, WANG Zhong-Peng, GAO Xi-Yan, ZHANG Zhao-Liang   

  1. Institute of Internal Combustion Engine, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China; College of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, P. R. China
  • Received:2009-11-19 Revised:2010-02-26 Published:2010-04-02
  • Contact: ZHANG Zhao-Liang E-mail:chm_zhangzl@ujn.edu.cn

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摘要：

利用X射线衍射(XRD), X射线光电子能谱(XPS), 原位红外(in situ IR)光谱和CO2程序升温脱附(CO2-TPD)等技术研究了K对Mg-Al水滑石复合氧化物(MgAlO)的表面改性. 结果表明, 当K负载量臆8%(w)时, K高度分散在MgAlO表面, 并与载体作用形成了新的Lewis碱位. 其中, K取代MgAlO弱碱位OH上的质子形成弱碱性的Mg(Al)-O-K; 与强碱位表面O2-结合形成强碱性的Mg-O-K. 当K负载量为5%-8%(w)时, 还存在与载体作用较弱并具有更强碱性的准自由KOx. K增强MgAlO碱性的本质是K的电荷转移到了表面氧负离子上.

关键词: 原位红外光谱, 水滑石, 钾, 表面改性, 碱性位

Abstract:

The surface modification of Mg-Al hydrotalcite mixed oxides (MgAlO) with K was investigated using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in situ infrared (in situ IR) spectroscopy, and temperature-programmed desorption of CO2 (CO2-TPD).We found thatKwas highly dispersed on the surface of MgAlO when the loading amount was less than 8% (w). New Lewis base sites were formed through the interaction between K and MgAlO. The weakly basic Mg(Al)-O-K resulted from the proton substitution of Mg(Al)-OH with K. Mg-O-K was obtained by combination with strongly basic O2- sites. At a K loading between 5% (w) and 8% (w), the quasi free KOx species that interacted weakly with the support and showed stronger basicity than Mg-O-K was formed. The increase in basicity of K/MgAlO can be attributed to charge transfer from K to the surface oxygen anions, which increases the negative charge of the strongly basic sites.

Key words: In situ IR, Hydrotalcite, Potassium, Surface modification, Basic site