摘要
用共沉淀法制备了Bi和Mo的复合氧化物固体材料 .运用XRD ,IR ,TPD和激光促进表面反应 (LSSR)技术研究了其晶体结构、表面构造、化学吸附特性和激光促进异丁烷选择氧化反应性能 .结果表明 :Bi Mo O复合氧化物含有α Bi2 Mo3 O12 和少量γ Bi2 MoO6晶相 ;其表面上存在着Lewis碱位 (MoO和Mo—O—Bi键中的O)及Lewis酸位 (Bi3 + ) ;异丁烷的两个甲基H分别吸附在两个相邻的Lewis碱位MoO上 ,形成双位分子吸附态 ;在常压和 2 0 0℃条件下 ,用一定频率的激光激发MoO键 10 0 0次 ,异丁烷的转化率可达 11 2 % ,其反应产物是异丁烯、甲基丙烯醛和甲基丙烯酸 ,其中甲基丙烯酸的选择性为 90 % .根据实验结果 ,探讨了激光促进异丁烷选择氧化为甲基丙烯酸的表面反应机理 .
A composite oxide catalyst containing Bi and Mo is prepared by coprecipitation method. Its surface composition and structure, chemisorption properties and behaviors in laser stimulated isobutane selective oxidation are investigated by techniques of XRD, IR, TPD and laser stimulated surface reaction (LSSR). The main phase component of Bi Mo O is α Bi 2Mo 3O 12 . Lewis basic sites O 2- , located at the surface Mo Oor Mo O Bi bonds, and Lewis acid sites Bi 3+ appear on the surface of the composite oxide. Two methyl hydrogen atoms in isobutane molecule can be chemisorbed on the terminal oxygen of neighboring Lewis basic sites Mo Obonds on the surface of the oxide. Using the laser photons of 984 cm -1 frequancy to excite the Mo Obond 1000 times under the conditions of 0 1 MPa and 200 ℃, the conversion of isobutane obtained is about 11 2%, the reaction products are isobutene, methylacrolein (MAL) and methacrylic acid (MAA), and the selectivity for MAA is over 90%. Based on the experimental results above, a possible mechanism is proposed for the laser stimulated isobatane selective oxidation to MAA.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2001年第2期129-132,共4页
基金
国家自然科学基金 !( 2 9773 0 3 1)
