SO_4^(2-)/Fe_2O_3型固体超强酸的制备及酯化催化活性的研究

The Preparation of Solid Superacids SO_4^(2-)/Fe_2O_3 and Their Catalytic Activity in Esterification

研究了由FeSO4·7H2 O直接焙烧制备SO2 -4/Fe2 O3 型固体超强酸时 ,焙烧温度、焙烧时间对催化剂性能的影响 ,并对制得的SO2 -4/Fe2 O3 型固体超强酸催化剂 ,测定了其SO2 -4与Fe2 O3 的摩尔比、表面酸度、酯化催化活性等数据 ,得到了SO2 -4/Fe2 O3 型固体超强酸的最佳制备条件 :焙烧温度 5 5 0℃ ,焙烧时间 5h。在此条件下 ,制得的SO2 -4/Fe2 O3 型固体超强酸催化剂中SO2 -4与Fe2 O3 的摩尔比为 1.71时 ,相应的表面酸度最大 (3.4 7mmol/g) ,对酯化反应的催化活性最好 ;SO2 -4与Fe2 O3 的摩尔比低于或高于这一数值 ,对应的表面酸度值都降低 ,对酯化反应的催化活性也降低。适量吸水会使SO2 -4/Fe2 O3 固体超强酸催化剂的表面酸度增加 ,从而使其对酯化反应的催化活性提高 ,但吸水过多 。

The solid superacid SO 2- 4/Fe 2O 3 was prepared by calcining FeSO 4·7H 2O directly and the influence of calcining temperature, calcining time to its catalytic activity in esterification was investigated. The data of the catalysts (such as mole ratio of SO 2- 4 and Fe 2O 3 and surface acidity etc) were obtained. The optimal condition in preparation of solid superacid SO 2- 4/Fe 2O 3 is: calcining temperature 550 ℃, calcining time 5 h. Under this condition the mole ratio of SO 2- 4 and Fe 2O 3 in the obtained solid superacid SO 2- 4/Fe 2O 3 was 1.71 and the corresponding acid concentration on its surface was maximal (3.47 mmol/g) so that its catalytic activity in esterification was the best. When the acid concentration on the catalyst surface was higher or lower than this value, its catalytic activity in esterification was decreased. When the catalyst absorbed suitable amount of water, its acid concentration on the catalyst surface and catalytic activity in esterification was increased too. On the other hand, if the catalyst absorbed much more water, its catalytic activity in esterification would be lost.