摘要
采用溶胶 凝胶法和浸渍法制备了V2 O5/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
V2O5/SiO2 catalyst samples were prepared by impregnation and sol-gel method, respectively. The surface composition, structure, chemisorbility and activity of V2O5/SiO2 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 (V5+) 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 -CH3. 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 -CH3, or chemisorbed on Lewis acid sites V5+ by C = C bond. The main products of the selective oxidation of isobutane are isobutene, methylacrolein, methylacrylic acid and COx on the catalyst. The reaction of intermediate product isobutene adsorbed on Lewis acid sites V5+ with the adsorbed active oxygen on the same sites is the main reason for the formation of deeply oxidative product COx.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2001年第6期563-566,共4页
基金
国家自然科学基金资助项目 ( 2 97730 31)
