表面活性剂对活性氧化铝孔结构的影响

研究了十二烷基苯磺酸钠和C12脂肪醇聚氧乙烯(3)醚对活性氧化铝孔结构的影响。实验结果表明,十二烷基苯磺酸钠和C12脂肪醇聚氧乙烯(3)醚能够使氧化铝平均孔径从11.98 nm分别移至6.32 nm和9.42 nm,比表面从193 m2/g分别增至241 m2/g和230 m2/g。这两种表面活性剂之所以能显著影响氧化铝孔分布,主要是因为,以氧原子为极性头的表面活性剂,不仅能够进入拟薄水铝石粒子间隙,而且能够插入拟薄水铝石层间,其氧原子与拟薄水铝石层表面的羟基以及水分子,通过氢键形成一种新的复合氧化铝。在焙烧的过程中,表面活性剂能够减小拟薄水铝石层表面和微孔内壁的应力,避免了层间的坍塌和毛细孔的收缩,从而影响氧化铝孔分布,且极性头小的表面活性剂影响效果优于极性头大的表面活性剂。

Influences of surfactants on pore structure in active alumina beads

Influences of C12-LAS and C12-AEO3 on pore structure in active alumina beads were studied.Experimental results showed that LAS and AEO3 can reduce the average diameter of the pores in active alumina beads from 11.98 nm to 6.32 nm and 9.42 nm respectively,as well as increase the specific surface area of active alumina beads from 193 m2/g to 241 m2/g and 230 m2/g respectively.Causes for such phenomena are that the surfactants with oxygen as polar head not only can enter the voids among the pseudoboehmite granules,but also can insert into spacing between the layers of the pseudoboehmite.Oxygen atoms of the surfactant combine with the hydroxyl groups at the layer surface of pseudoboehmite and the water molecules by hydrogen bonds forming a kind of new complex alumina.During the calcining process,the surfactant can reduce the stress on the layer surface and micropore wall of pseudoboehmite,avoid collapse of layers and shrink of capillaries,thereby result in the influence on the distribution of the pores in the alumina beads.The influence of surfactants with smaller polar head is better than that of surfactants with bigger polar head.