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与液体酸和酸性树脂催化剂相比,固体超强酸催化剂具有许多优点,如无腐蚀性、不污染环境、易与产物分离和重使用性等。通过沉淀、老化、过滤、洗涤、干燥、浸渍、焙烧等过程,从ZrOCl2·8H2O和(NH4)2SO4制备了SO42-/ZrO2固体超强酸催化剂;使用Hammett指示剂法和吡啶吸附的FT-IR光谱法测定了其酸强度和酸中心类型;以甲醇、乙酸和乙酸乙酯吸附在SO42-/ZrO2固体超强酸催化剂上的FT-IR光谱,推测酯化反应机理。结果表明,当焙烧温度高于500℃,SO42-/ZrO2可以形成超强酸,其表面上同时存在Lewis酸和Bronsted酸中心;在SO42-/ZrO2固体超强酸催化剂上,酯化反应既可以在Lewis酸中心进行,也可以在Bronsted酸中心上进行。
Compared with liquid acid and acid resin catalysts, solid superacid catalysts have many advantages, such as non-corrosive, non-polluting environment, easy separation and reuse of products and so on. The SO42- / ZrO2 solid superacid catalyst was prepared from ZrOCl2.8H2O and (NH4) 2SO4 by precipitation, aging, filtration, washing, drying, impregnation and calcination. The FT-IR spectrum The acidity and the type of acid center were determined. The FT-IR spectra of methanol, acetic acid and ethyl acetate adsorbed on SO42- / ZrO2 solid superacid catalysts were deduced to predict the esterification reaction mechanism. The results show that when the calcination temperature is higher than 500 ℃, SO42- / ZrO2 can form superacid and Lewis acid and Bronsted acid center exist on the surface. On SO42- / ZrO2 solid superacid catalyst, Acid center, but also in the Bronsted acid center.