微乳液法制备高比表面积γ-Al2O3及其表征

摘要

High surface area γ-Al2O3 samples were prepared by the cetyl trimethyl ammonium bromide (CTAB)/n-hexyl alcohol/water microemulsion system and their physical properties and structures were characterized by FTIR, SEM, XRD and nitrogen adsorption and desorption. Results showed that the prepared γ-Al2O3 samples had layer structure and uniform particle sizes (average 48-56nm) and concentrated pore size distribution, and the most probable pore diameter of DFT method was 2.769nm for γ-Al2O3-2.5,γ-Al2O3-2.75 andγ-Al2O3-3.00. The salt solution concentration in microemulsion system had great impact on the external specific surface area and the micropore specific surface area. When the salt concentration changed from 2.25mol/L to 3.00mol/L, the external specific surface area increased significantly from 130m2/g to 241.1m2/g. However, the salt concentration in microemulsion system had little effect on the BET surface areas which were 402.9-421.5 m2/g.%采用微乳液法制备高比表面积的γ-Al2O3，利用傅里叶变换红外光谱、场发射扫描电镜、X射线衍射、氮气低温吸附脱附对产品的物理性质和结构特性进行表征。结果表明：十六烷基三甲基溴化铵/正己醇/水溶液的微乳体系所制得的γ-Al2O3为形貌统一的层状结构，粒度均匀，平均粒径为48~56nm，DFT法孔径分布集中，样品γ-Al2O3-2.5,γ-Al2O3-2.75和γ-Al2O3-3.00的最可几孔径为2.769nm。体系当中盐溶液的浓度对外比表面积和微孔比表面积影响较大，盐溶液浓度由2.25mol/L变化至3mol/L时，外比表面积由130 m2/g显著增大至241.1m2/g，但盐溶液浓度对BET比表面积影响不大，比表面积为402.9~421.5m2/g。