铝改性固体酸催化剂的制备及其在正己烷异构化中的反应性能研究

以拟薄水铝石为黏结剂，采用混捏法分别制备了负载金属钯的丝光沸石型催化剂和SO^2-₄/ZrO₂型超强酸催化剂。利用X射线衍射、N₂物理吸附、NH₃程序升温脱附和H₂程序升温还原等分析手段对催化剂进行了表征，并且利用正己烷异构化反应评价催化剂的催化性能。结果表明，Al的加入不会影响丝光沸石的晶型和微孔特性；对超强酸来说，Al的添加可以稳定锆的四方晶型并增大其比表面积，有利于反应的进行。相比于丝光沸石，超强酸具有更加广泛的酸强度分布，并且Al的添加对催化剂酸性有显著影响。正己烷异构化反应表明：超强酸催化剂的最佳反应温度比丝光沸石低110℃左右。当氧化铝添加量达到25%（质量分数）时，超强酸催化正己烷异构化反应转化率可稳定在90%以上，2,2-二甲基丁烷（2,2-DMB）的选择性稳定在38%以上。

Preparation of Aluminum Modified Solid Acid Catalysts and Their Reactivity Ability in the Isomerization of n-Hexane

Palladium loaded mordenite and SO _2-⁴/ZrO₂ catalysts were synthesized by kneading method, using pseudo-boehmite as the binder. The catalysts were characterized by XRD, BET, NH₃-TPD and H₂-TPR, and the reactivity ability of catalyst was evaluated by the isomerization of n-hexane.The results show that the crystalline phase and microporous characteristics are not changed when alumina source is added.And for the sulfated zirconia, the added alumina can stabilize the tetragonal phase and enhance the specific surface area, which are useful for the isomerization reaction. Compared with mordenite, the superacid has a wider acid distribution, and the added alumina has a remarkable influence on the acidity. With respect to the isomerization of n-hexane, the optimum reaction temperature of superacid is lower 11℃ than that of mordenite. For the superacid catalyst, when the amounts of alumina is up to 25% (mass fraction), its conversion is close to 90%, and the selectivity of 2,2-dimethylbutane (2,2-DMB) is 38%.