摘要
采用两步浸渍法制备钾改性的Mo/SBA-15催化剂.采用N2吸附,X射线衍射(XRD),透射电镜(TEM),紫外-可见(UV-Vis)吸收光谱,拉曼(Raman)光谱,NH3程序升温脱附(NH3-TPD),CO2程序升温脱附(CO2-TPD),H2程序升温还原(H2-TPR)等手段表征催化剂的物理化学性质.研究结果表明,在Mo0.75/SBA-15中添加K之后,有新物种钾钼酸盐生成,并且当K/Mo的摩尔比不同时,钼物种的存在状态也不同.添加钾之后,催化剂的活性和总醛(甲醛、乙醛、丙烯醛)的选择性均有所提高,并且受钾的添加量影响.在575°C时,在K0.25-Mo0.75/SBA-15催化剂上醛的收率可高达8.5%(摩尔分数).
Potassium-modified SBA-15-supported molybdenum oxide catalysts were prepared using a two- step impregnation method. The physical and chemical properties of the catalysts were characterized using N2- adsorption-desorption, X-ray diffraction （XRD）, transmission electron microscope （TEM）, UV-visible （UV-Vis） spectroscopy, Raman spectroscopy, NH3 temperature-programmed desorption （NH3-TPD）, CO2 temperature- programmed desorption （CO2-TPD）, and H2 temperature-programmed reduction （H2-TPR）. The results showed that potassium addition resulted in the formation of new potassium molybdates, and the states of molybdenum species varied with changes in the K/Mo molar ratio. The addition of potassium to Mo0.75SBA-15 effectively improved the activity of catalysts and the selectivity to the total aldehydes （formaldehyde, acetaldehyde, and acrolein）, especially for acetaldehyde in the selective oxidation of ethane. The turn-over frequency （TOF） and product selectivity depended strongly on the potassium content. The maximum selectivity and yield of aldehydes were obtained by varying the K/Mo molar ratio. At 575 ℃, the maximum yield of aldehydes reached 8.5% （molar fraction） over K0.25-Mo0.75/SBA-15 catalyst. The formation of new potassium-molybdates promoted the activities and selectivities of the catalysts.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2014年第9期1736-1744,共9页
Acta Physico-Chimica Sinica
基金
supported by the National Natural Science Foundation of China(21376261,21173270,21177160)
Natural Science Foundation of Beijing,China(2142027)
National High-Tech Research and Development Program of China(863)(2013AA065302)
Specialized Research Fund for the Doctoral Program of Higher Education,China(20130007110007)~~
