钾对镁铝水滑石复合氧化物的表面改性  

Surface Modification of Mg-Al Hydrotalcite Mixed Oxides with Potassium

作　　者：张业新[1,2] 苏庆运[1] 王仲鹏[2] 高希彦[1] 张昭良[2] 

机构地区：[1]大连理工大学内燃机研究所,辽宁大连116024 [2]济南大学化学化工学院,济南250022

出　　处：《物理化学学报》2010年第4期921-926,共6页Acta Physico-Chimica Sinica

基　　金：国家高技术研究发展计划(863)(2008AA06Z320);国家自然科学基金(20777028);山东省自然科学基金(2007ZRB01259);山东省博士基金(BS2009HZ010)资助项目~~

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≤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.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 that K was 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.

关 键 词：原位红外光谱 水滑石 钾 表面改性 碱性位 

分 类 号：O611.3[理学—无机化学]