CO_2氧化异丁烷制异丁烯用Pd/V_2O_5-SiO_2催化剂  

Pd/V_2O_5-SiO_2 Catalyst for Oxidative Dehydrogenation of Isobutane with CO_2 to Isobutene

作　　者：王茂功[1] 钟顺和[1] 

机构地区：[1]天津大学化工学院,天津300072

出　　处：《催化学报》2007年第2期124-130,共7页

基　　金：国家重大基础研究前期研究专项(2001CCA03600).

摘　　要：利用表面化学反应改性法制备了不同V2O5负载量的V2O5-SiO2表面复合物载体,进而采用等体积浸渍法制备了负载型Pd催化剂.用N2吸附、X射线衍射、透射电镜、X射线光电子能谱、程序升温脱附、化学吸附-红外光谱和微反技术对系列Pd/V2O5-SiO2催化剂的比表面积、晶相结构、价态、异丁烷的化学吸附性能和CO2部分氧化异丁烷制异丁烯的催化性能进行了研究.结果表明,Pd/V2O5-SiO2催化剂中的钒以V5+形式存在,V5+在催化剂表面形成活性位V=O,其中V=O晶格氧与i-C4H10分子的-CH3和-CH中的H产生化学吸附作用;催化剂中金属Pd与V4+协同作用使CO2在催化剂上产生了卧式吸附态;晶格氧参加了催化氧化反应,催化剂中V5+←→V4+的变化构成了催化反应的氧化还原过程.在525℃,CO2/i-C4H10体积比为1和空速为1200h-1的条件下,以Pd/25%V2O5-SiO2为催化剂时异丁烷转化率为22.8%,异丁烯选择性为89.1%.A series of supported Pd catalysts were prepared by incipient impregnation using a V205-SiO2 surface complex prepared by surface modification as the support. Their structure, valence states, chemisorption properties for isobutane, and catalytic activity for isobutane partial oxidation with CO2 were characterized by N2 adsorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperatureprogrammed desorption, chemisorption-infrared spectroscopy, and microreactor techniques. The results showed that the lattice oxygen of V=O was the active site on the Pd/V2Os-SiO2 catalyst, and the valence of vanadium in the V=O was positive 5. Isobutane was chemisorbed on the lattice oxygen of V=O through the H atoms in -CH3 and -CH of i-C4H10. Carbon dioxide was chemisorbed horizontally on the catalyst through the synergetic effect of Pd and V^4＋ . The ^V5＋←→V^4＋ couple played a key role in the redox mechanism of the catalytic reaction. In the presence of Pd/25 % V205-SiO2 and under the conditions of 525 C , 0.1 MPa, CO2/i-C4H10 volume ratio of 1, and mixed gas space velocity of 1 200 h- 1, 22.8 % conversion of isobutane and 89.1% selectivity for isobutene were achieved.

关 键 词：钯 氧化钒 氧化硅 表面复合物 二氧化碳 异丁烷 氧化脱氢 异丁烯 

分 类 号：O643.36[理学—物理化学]