摘要
以非离子型表面活性剂伯胺为模板剂合成了含铁介孔分子筛FeHMS,并对其结构和形态进行了表征.发现FeHMS的颗粒比SiHMS小,粒子表面更为光滑.除了2.5nm的介孔外,FeHMS还有10nm左右的孔.FeHMS介孔分子筛在脱除模板剂之前,铁主要处于四面体配位状态的骨架位,经焙烧脱除模板剂之后,部分铁由骨架位迁移到孔壁表面.用酸化的乙醇溶液抽提脱除模板剂,能更有效地让铁保留在四面体配位状态的骨架位上.高温脱除模板剂后,孔壁表面的铁物种处于一种高分散的状态.此外还研究了HMS类介孔分子筛材料的水热稳定性,发现铁的引入可改善介孔分子筛材料的水热稳定性.
We synthesized and characterized Fe - containing hexagonal mesoporous silica (FeHMS) molecular sieves by means of some modern physico - chemiscal techniques (XRD, SEM, TEM, BET, TG/DTA, FT-IR, EPR, Mossbauer spectroscopy, etc.), together with NH3 - TPD. We found more iron still retain in the framework after removal of the surfactant. The particle of FeHMS is smaller than that of SiHMS, and its surface is smoother. The pore size distribution of FeHMS reveals that there are two type mesopores, with diameters being 2.5nm and 10nm, respectively. It is found that Fe is mainly in the tetrahedral coordinated framework in as- synthesized samples. After removal of the template by calcination, a part of Fe transfers to the wall surface. In case of using acidified alcohol to extract surfactant, it is more effective to retain Fe in tetrahedral coordinated framework. Fe species on wall surface are of high dispersion when removing the surfactant at high temperature. The results indicate that the introduction of Fe could improve the hydrothermal stability. It seems that the octahedral Fe ( III ) species is responsible for the above improvement. Owing to the thicker wall, FeHMS appears to possess better thermal and hydrothermal stability than FeMCM - 41.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2000年第1期75-81,共7页
Acta Chimica Sinica
关键词
介孔分子筛
FeHMS
合成
伯胺
模板剂
mesoporous molecular sieves, FeHMS, synthesis, characterization
