氧化铝对银催化剂及其载体性能的影响

摘要

在银催化剂的α-氧化铝载体的制备过程中添加了氧化铝粉末,采用SEM、压汞法和XPS等方法对制备的氧化铝粉末、α-氧化铝载体和银催化剂进行了表征,在微型固定床反应器中评价了银催化剂的乙烯环氧化性能,研究了添加氧化铝粉末对银催化剂及α-氧化铝载体性能的影响.实验结果表明,添加氧化铝粉末能改善α-氧化铝载体的孔结构和形貌,载体的孔径分布向较大孔径方向移动,平均孔径和中值孔径增大,氧化铝片层变小、变厚,逐渐向块状形貌转变;添加氧化铝粉末还能增强银颗粒与载体之间的作用力,改善银颗粒在载体表面的分散性,提高银催化剂的活性和稳定性,延长催化剂的使用寿命.%α-Alumina carriers of silver catalyst were prepared by adding alumina powder. The effect of alumina powder on silver catalyst and α-alumina carrier was studied. The prepared alumina powder,α-alumina carriers and silver catalysts were characterized by XRD,mercury penetration method and XPS. The catalytic performances of the silver catalysts in ethylene epoxidation were evaluated in a micro fixed bed reactor. The results indicated that the addition of alumina powder improved the pore structure and morphology of carrier. The pore size distribution of the carrier moved to the larger aperture and the average pore diameter and the median pore diameter increased. The alumina layer became smaller and thicker,and gradually changed to the bulk shape. The dispersion of silver particles on the surface of the carrier was improved. The forces between silver particles and carrier was enhanced,and further the catalytic performance of the silver catalyst was improved, including activity,stability and life.