CAJ | 학술논문

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CO_2程序升温脱附(CO_2-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O~(2-)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KO_(x*)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.
이용X사선연사(XRD),X사선광전자능보(XPS),원위홍외(in situ IR)광보화CO_2정서승온탈부(CO_2-TPD)등기술연구료K대Mg-Al수활석복합양화물(MgAlO)적표면개성.결과표명,당K부재량≤8%(w)시,K고도분산재MgAlO표면,병여재체작용형성료신적Lewis감위.기중,K취대MgAlO약감위OH상적질자형성약감성적Mg(Al)-O-K;여강감위표면O~(2-)결합형성강감성적Mg-O-K.당K부재량위5%-8%(w)시,환존재여재체작용교약병구유경강감성적준자유KO_(x*)K증강MgAlO감성적본질시K적전하전이도료표면양부리자상.
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 CO_2(CO_2-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 O~(2-) sites.At a K loading between 5%(w)and 8%(w),the quasi free KO_x 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.