MoO_3/TiO_2纳米复合催化剂的合成及催化脱氢性能

Synthesis and catalytic dehydrogenation properties of MoO_3/TiO_2 complex nanocatalyst

采用溶胶-凝胶法合成MoO3/TiO2、K2O-MoO3/TiO2、V2O5-MoO3/TiO2、Al2O3-MoO3/TiO2、K2O-V2O5-MoO3/TiO2系列纳米催化剂。借助TEM、XRD、IR等技术对催化剂进行了表征,并利用环己烷催化氧化脱氢成环己烯的反应进行活性测试。结果表明,MoO3在载体TiO2呈单层和多层分布,单层分布时发生了Mo与O—Ti的键合作用,同时使TiO2表面水分子发生解离反应,活化时脱去—OH产生Mo6+和Mo—O-活性中心;多层分布时以MoO、Mo—O-活性物种为主。脱氢中心和供氧中心之间存在协同作用,K、Al、V均能影响其协同作用。

Abstract： A series of MoO3/TiO2, K2O-MoO3/TiO2, V2O3-MoO3/TiO2, Al2O3-MoO3/TiO2 and K2O- V2O3-MoO3/TiO2 were prepared by the sol-gel method, and characterized with TEM, XRD and IR. The catalytic activity of oxydehydrogenation of cyclohexane to cyclohexene was tested. The results showed that MoO3 was distributed on the carrier of TiO2 with monolayer or/and muhilayer. The Mo in the monolayer was bonded with O-Ti structure, and caused dissociation of the water molecules on the surface of TiO2, and the activity centre of Mo^6＋ and Mo-O^- species were formed by means of activation to eliminate the hydroxyl group. For the muhilayer structure the main active species were Mo=O and Mo-O^- . A synergetic effect existed between the dehydrogenation centre and the oxygen-supply centre, and was affected by the addition of K, Al or V.