高温水蒸气处理对氧化铝孔结构的影响

EFFECT OF STEAM ACTIVATION ON PORE STRUCTURE OF ALUMINA

研究了水蒸气处理对氧化铝孔结构的影响,并运用XRD、氮吸附脱附仪、汞孔计和核磁共振谱仪等对氧化铝的晶相、比表面积、孔分布及Al原子的状态进行表征。结果表明,水蒸气处理能够使氧化铝微孔及中孔的最可几孔半径增大,大孔的最可几孔半径减小,从而制备出大孔体积、低堆密度、低比表面积的活性氧化铝。其主要原因在于:水蒸气的存在,有利于六配位铝原子发生迁移,改变了Al2O3粒子间的堆积方式,使晶粒长大,结构有序度增加。

Steam activation is an important way to modi{y the pore structure of alumina Techniques such as XRD, nitrogen adsorption-desorption, mercury porosimetr resonance （NMR） spectrometer were employed to characterize the crystalline ph y and nuclear support. magnetic ases, surface area, pore size distribution and A1 atom chemical shift of these samples. The results show that steam activation can make alumina micropore size larger and macropore size reduction. An activated alumina with larger pore volume, lower bulk density and low surface area can be prepared by the steam treatment. The main rea- son for the changes of alumina pore structure by steam treatment is the presence of water vapor. The vapor makes the six ligand aluminum atom migrate easily, thus changes the way of the accumulation of Al2 O3 particles, resulting in grain growth and structure order degree increase.