SiO2负载CeO2催化氧化芴制备芴酮

摘要

The catalytic liquid-phase oxidation of fluorene to 9-fluorenone is limited by the difficulties of continuous production for industrialization and waste water generated in production. CeO2/SiO2 catalysts were prepared by impregnation method,precipitation method and sol-gel method,respectively. Their activities for oxidation of fluorene to 9-fluorenones were investigated. The catalysts were characterized by XRD,H2-TPR,CO2-TPD and HRTEM. The catalytic performances of catalysts for oxidation of fluorene to 9-fluorenone were examined. The experimental results indicate that the conversion of fluorene on CeO2 is determined by the reduction temperature of CeO2,the concentration of oxygen vacancies and the concentration of surface oxygen. The selectivity of fluorenone on CeO2is related to the amount and intensity of surface basicity. The catalysts prepared by the sol-gel method have the best dispersion and show the best catalytic activity. Under the reaction conditions of temperature of 370℃,WHSV of 0.5h-1,gas liquid ratio of 250,the conversion of fluorene was 83% and the selectivity was 60%.%由于在工业上液相催化氧化法制备芴酮无法连续生产以及产生大量废水的缺点,本文以SiO2为载体,分别采用浸渍法、沉淀法和溶胶凝胶法制备了CeO2/SiO2催化剂,用于空气气相催化氧化芴制备芴酮.通过X射线衍射(XRD)、氢气程序升温还原(H2-TPR)、二氧化碳程序升温脱附(CO2-TPD)、高分辨率透射电子显微镜(HRTEM)等手段对所制备的催化剂进行表征,考察了不同方法制备的CeO2/SiO2对芴选择性催化氧化的影响,结果表明芴在CeO2活性组分上的转化率与CeO2还原温度、表面氧空位浓度以及表面氧浓度有关.芴酮在CeO2活性组分上的选择性与CeO2表面碱量以及碱性有关.在3种制备方法中,采用溶胶凝胶法制备的CeO2/SiO2分散性最好,催化活性最佳,在反应温度370℃、质量空速0.5h-1、气液比250时,芴的转化率可达到83%,选择性可达到60%.