气凝胶骨架镶嵌的 CeO2 纳米团簇催化氧化 HCl 制 Cl2

摘要

CeO2 nanoclusters inserted into aerogel matrix (CeO2@MxOy, MxOy= SiO2, ZrO2, Al2O3) prepared by a single-step sol-gel method were used as catalysts for recycling Cl2 from HCl oxidation. Due to their remarkable quantum-size effects, the properties of CeO2 nanoclusters were significantly different from crystal phase CeO2. The CeO2 nanoclusters could be completely reduced at the temperature range for reduction of the surface oxygen species of crystal phase CeO2. The unique properties of CeO2 nanoclusters resulted in the high activity of CeO2@MxOy in the process of HCl oxidation reaction. 40CeO2@SiO2 exhibited the highest activity and the STY (space time yield of Cl2) reached to 2.10 g·(g cat)?1·h?1 at 430℃ with VO2/VHCl of 1 and contact time of 0.1598 h. Kinetic studies showed that both O2 and HCl competed for the active sites rendering desorption of surface Cl as the rate-determining step.%采用一步溶胶-凝胶法制备了镶嵌于气凝胶骨架内的 CeO2 纳米团簇催化材料(CeO2@MxOy, MxOy= SiO2、ZrO2、Al2O3)用于 HCl 催化氧化反应.镶嵌于气凝胶骨架内的 CeO2 纳米团簇显著的量子尺寸效应导致其表现出不同于晶相 CeO2 的特性,H2-TPR 测试结果显示在晶相 CeO2 表面氧物种还原温区内 CeO2 纳米团簇即可被充分还原.优异的氧化还原性能导致 CeO2@MxOy 在 HCl 氧化过程具有良好的催化活性,其中,40CeO2@SiO2 的活性最高,在接触时间为 0.1598 h,VO2/VHCl 为 1,430℃时,Cl2 空时产率可以达到 2.10 g·(g cat)?1·h?1.催化剂表面的 HCl氧化反应同时受 O2 分压和 HCl 分压的影响,这表明 Cl2 从催化剂表面的脱附是该反应的决速步骤.