摘要
在异丙醇铝制备氧化铝工艺的三个阶段(拟薄水铝石形成前、形成后和焙烧后)添加稀土元素镧制备改性氧化铝材料。通过N_(2)吸脱附,XRD,XPS,TG,ICP-OES,SEM-EDS等表征方法研究了三种镧改性工艺的差异及其改性机理。结果表明:在拟薄水铝石形成前改性工艺中,镧倾向于在氧化铝表面富集,阻碍氧化铝晶粒的生长,氧化铝晶粒较小、表面能较高,使得老化过程中容易生成α-Al_(2)O_(3),导致样品热稳定性较差。在拟薄水铝石形成后改性工艺中,部分镧离子被包埋在氧化铝颗粒内,氧化铝表面的高分散相镧含量较低,造成样品热稳定性较差。在拟薄水铝石焙烧后改性工艺中,镧以高分散相状态在氧化铝颗粒的内外表面均匀分散,可有效减缓老化过程中α-Al_(2)O_(3)和LaAlO3等杂相生成,样品表现出较高的热稳定性。
The lanthanum-modified alumina materials were prepared by adding lanthanum element in three stages of preparation process for alumina from aluminumisopropoxide(before formation,after formation,and after calcination of pseudo-boehmite).The differences and modification mechanisms of the three lanthanum modification processes were researched by N_(2)adsorption and desorption,XRD,XPS,TG,ICP-OES,and SEM-EDS.The results show that the lanthanum tends to be enriched to the surface of alumina,which impedes the growth of alumina grains in the modification process before the boehmite formation.Because of the small grain size and high surface energy of alumina,α-Al_(2)O_(3)is easily formed during the aging process,resulting in poor thermal stability of the sample.When modification after the formation of pseudo-boehmite,part of the lanthanum ions are embedded in alumina particles.The highly dispersed lanthanum content on the surface of the sample is low,so the sample has poor thermal stability.In the modification process after calcination of pseudo-boehmite,lanthanum ions are uniformly dispersed on the inner and outer surfaces of alumina particles in a highly dispersed state,which can effectively slow down the formation of impurity phases such asα-Al_(2)O_(3)and LaAlO_(3)during the aging process,so the sample shows higher thermal stability.
作者
赵博
董洁
王军
张慧
沈美庆
Zhao Bo;Dong Jie;Wang Jun;Zhang Hui;Shen Meiqing(College of Chemistry and Chemical Engineering,Qingdao University,Qingdao 266071,China;College of Chemistry and Chemical Engineering,Tianjin University,Tianjin 300350,China)
出处
《中国稀土学报》
北大核心
2025年第4期853-862,共10页
Journal of the Chinese Society of Rare Earths
关键词
镧
氧化铝
热稳定性
改性工艺
lanthanum
alumina
thermal stability
modification processes
作者简介
赵博(1999-),男,硕士研究生;董洁(1992-),男,博士研究生;通讯联系人:张慧,男,副教授,研究方向:天然产物开发。E-mail:zhanghui8547@163.com;通讯联系人:沈美庆,男,教授,研究方向:机动车尾气净化。E-mail:mqshen@tju.edu.cn。
