基于阳极Al2O3的非涂覆式金属基体整体催化剂载体的制备

摘要

Porous anodic alumina (PAA) films were prepared by a two-step anodization in oxalic acid.The effect of anodizing conditions (voltage, time, electrolyte concentration, and temperature) on structural features was investigated under the metallic monolith structure.PAA film was treated hydrothermally for 1.5 h at 80 ℃, then roasted 3 h at 500 ℃.Results showed that pore diameter and film thickness increased linearly with the increase of anodization voltage (or electrolyte concentration, or anodization time).Exponential relations between pore diameter (or film thickness) and electrolyte temperature, and between pore density and voltage were confirmed.No effect of anodization time, temperature and concentration of the electrolyte on pore density was found.The surface area of the plate could be increased to 3 200 times, and the electrolyte temperature were considered to be the most effective factor to enlarge the surface area.When the PAA was subjected into hot water at 80 ℃ for 1.5 h, its surface area increased from 13.5 m2/g to 180.3 m2/g, accompany with the transformation of alumina from amorphous to gamma form.The serrated honeycomb prepared with "anodization-hydrothermal treatment-calcination" had higher surface area, bigger open frontal area and smaller bulk density than commercial cordierite honeycomb.%通过草酸溶液中的二步氧化法制备多孔阳极Al2O3(PAA)膜.在保持金属一体化结构下,考察阳极氧化条件(电压、时间、电解液浓度及温度)对多孔Al2O3膜的结构特性的影响.在80 ℃下对PAA膜进行水热处理1.5 h并在500 ℃下焙烧3 h.结果表明:孔径和膜厚随电压(或电解质浓度、阳极氧化时间)增加呈线性增长,孔径(或膜厚)和电解液温度呈指数型关系,孔密度和电压关系亦然;另一方面,氧化时间、电解液温度、电解液浓度对孔密度几乎没影响;平板的表面积最大可提高到3 200倍,提高电解液的温度被认为是扩大表面积最有效的方法.水热处理后表面积可以从13.5 m2/g增加到180.3 m2/g,并将无定形骨架Al2O3转变为γ-Al2O3.通过阳极氧化-水热处理-焙烧制得的锯齿状蜂窝体与商业的堇青石蜂窝体相比,比表面积略高,有更大的开孔率和更轻的质量.