MoO3/SiO2催化剂的异丁烷选择氧化反应性能

分别采用浸渍法和溶胶－凝胶法制备了MoO3/SiO2催化剂，用XRD，TPR，IR，TPD和活性评价等手段对催化剂的影响，晶格氧活泼性，化学吸附性能和异丁烷选择氧化反应性能进行了研究。结果表明，催化剂表面由Lewis碱位Mo=M,Mo-O-Mo中的晶格氧和Lewis酸位Mo^6 构成，在MoO3/SiO2催化剂上，异丁烷主要通过甲基的H双位吸附在表面的Lewis碱位Mo=O上；在常压条件下，异丁烷选择氧化产物主要为异丁烷，甲基丙烯醛和甲基丙烯酸，其中深度氧化产物CO2主要由吸附的异丁烯继续反应生成；采用溶胶－凝胶法制备的MoO3/SiO2催化剂，可得到较高的异丁烷转化率和含氧有机物选择性。

Study on Selective Oxidation of Isobutane over MoO3/SiO2 Catalysts

The MoO\-3/SiO\-2 catalysts were prepared by impregnation method or Sol\|Gel method. The surface composition, activity of lattice oxygen, chemisorbility and reactivity of the catalysts were systemically studied by using the techniques of XRD, IR, TPD and micro\|reactor. The results showed that there exist Lewis base sites (Mo=O and Mo-O-Mo) and Lewis acid sites (Mo\++) on the surface of these catalysts. Isobutane can be chemisorbed on surface terminal oxygen of Lewis base sites Mo=O by one or two H atoms in -CH 3. The mainly products of the selective oxidation of isobutane are isobutene, methylacrolein, methylacrylate acid and CO x on MoO\-3/SiO\-2 catalysts. The reaction of intermediate product isobutene with the adsorbed active oxygen on the same sites is the mostly reason of the formation of deeply oxidation products CO x . The conversion and selectivity on MoO\-3/SiO\-2 catalyst prepared by sol\|gel method are higher than that on MoO\-3/SiO\-2 catalyst prepared by impregnation method.