酸碱改性高岭土性能的研究 Ⅱ.比表面积和孔结构

研究了酸、碱改性高岭土的孔结构性质以及影响酸改性高岭土比表面积的因素。结果表明，多种酸反应体系相比，在Ａｌ２Ｏ３／ＨＣｌ体系中形成的酸改性白土具有明显的中孔分布，提高反应温度，中孔特征突出，孔道更加通畅。碱改性白土的吸附脱附等温线为Ⅳ型，具有典型的中孔特征。高岭土经过酸或碱改性，都可以获得平均孔径在４．０ｎｍ左右的中孔材料，但是碱改性白土的吸附量更大，孔分布更集中。另外，酸量和酸浓度适中才有利于提高改性高岭土的比表面积，提高反应温度和延长反应时间也可以增加其比表面积

RESEARCH ON PERFORMANCE OF ACID AND ALKALI MODIFIED KAOLINS . Surface Area and Pore Structure

The pore structures of the acid and alkali modified kaolins and the factors affecting the surface area of acid modified kaolin were investigated by nitrogen adsorption. In comparison with other acid reaction systems, the acid modified kaolin obtained from Al2O3/HCl system showed obvious mesoporous distribution and its mesoporous character was strengthened at higher temperature. The adsorption and desorption isothermal curves of alkali modified kaolin were attributed to type IV, which showed typical mesoporous distribution features. The mesoporous material with average diameter of 4.0nm could be obtained from kaolins either modified by acid or alkali, and the latter had larger adsorption capacity and more uniform pores. Furthermore, only appropriate acid content and acid concentration can increase the surface area of modified kaolin, however, which can also be increased by extending the reaction time and raising the reaction temperature.