摘要
采用浸渍法制备了不同V2O5负载量(分别为5%和15%)的V2O5/CeO2催化剂.利用不同激发波长(514和325nm)的Raman光谱,结合X射线衍射(XRD)、紫外-可见漫反射(UV-VisDRS)和N2物理吸附技术,考察了V2O5/CeO2催化剂中V2O5和载体CeO2之间的固相反应.结果表明:催化剂在300℃焙烧时,V2O5与CeO2反应生成CeVO4,升高温度有利于固相反应的发生.样品对325nm光的吸收明显大于对514nm光的吸收,因此325nm激发波长的Raman光谱对催化剂的表层信息更为敏感.当焙烧温度较低时,由于受到表层CeVO4的阻碍,未反应的V2O5残留在载体CeO2孔道或粒子堆积孔道内部,因此514nm激发波长下能观察到V2O5的Raman峰,而表面灵敏的325nm激发波长下观察不到此现象.
We prepared V2O5/CeO2 catalysts with different V2O5 loadings（5% and 15%） by incipient wetness impregnation.Raman spectroscopy（514 and 325 nm excitation laser lines）,X-ray diffraction（XRD）,UV-visible diffuse reflectance spectroscopy（UV-Vis DRS）,and N2 adsorption were used to study the solid-state reaction between V2O5 and CeO2.We found that the vanadium oxidation species reacted with ceria and formed a CeVO4 phase on the surface of the sample that was calcined at 300℃,and the reaction was promoted at higher temperature.In addition,the absorption at 325 nm is stronger than that at 514 nm for the sample,therefore,325 nm Raman spectroscopy is more sensitive to surface information than 514 nm Raman spectroscopy.Calcination at low temperature leads to unreacted V2O5 in the pores of CeO2 but this is hindered by CeVO4 on the sample surface.Therefore,the Raman band of V2O5 is present when using the 514 nm excitation laser line and absent when using the 325 nm excitation laser line.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2010年第9期2417-2421,共5页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(20873125)资助项目~~
