V2O5/SiO2催化剂的异丁烷选择氧化反应性能

 采用溶胶－凝胶法和浸渍法制备了V2O5／SiO2催化剂，并用XRD，IR，TPD和活性评价等手段对催化剂的表面构造、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V＝O双键的端氧和Lewis酸位V5＋构成，异丁烷分子主要通过甲基中的H双位吸附在催化剂表面的Lewis碱位上，异丁烯分子可通过甲基的H吸附在催化剂表面的Lewis碱位，也可通过C＝C双键吸附在催化剂表面的Lewis酸位上．在常压条件下，异丁烷选择氧化产物主要有异丁烯、甲基丙烯醛和甲基丙烯酸，其中深度氧化产物CO2主要由通过C＝C吸附的异丁烯继续反应生成．

Study on Selective Oxidation of Isobutane over V2O5/SiO2 Catalyst

V 2O 5/SiO 2 catalyst samples were prepared by impregnation and sol gel method, respectively. The surface composition, structure, chemisorbility and activity of V 2O 5/SiO 2 were systematically studied by using XRD, IR, TPD and micro reactor. The results showed that there exist Lewis base sites ( V=O and V O V) and Lewis acid sites (V 5+ ) on the surface of the catalyst. Isobutane can be chemisorbed on the terminal oxygen of Lewis base sites V=O bonds by one or two H atoms in CH 3. Isobutene can be chemisorbed on the terminal oxygen of Lewis base sites V=O and on the bridging oxygen in V O V bonds by two H atoms and one C atom in CH 3, or chemisorbed on Lewis acid sites V 5+ by C=C bond. The main products of the selective oxidation of isobutane are isobutene, methylacrolein, methylacrylic acid and CO x on the catalyst. The reaction of intermediate product isobutene adsorbed on Lewis acid sites V 5+ with the adsorbed active oxygen on the same sites is the main reason for the formation of deeply oxidative product CO x .