Abstract: The catalyst of solid superacid SO₄^2-/TiO₂ supported on HZSM-5 was prepared by sol-gel process. The trimethylolpropane oleate was synthesized by direct esterification. The catalyst was characterized by IR, XRD, BET, and SEM. The results show that SO₄^2-/TiO₂ with the form of nanoparticles is supported on the surface of HZSM-5, the BET surface area of the catalyst is up to 309.2m²/g, increasing 45.6m²/g compared with HZSM-5, and the catalyst is with better solid acidity. The effects of catalyst preparation conditions on catalytic reactivity were studied. The optimal condition for the preparation of the catalyst was obtained as follows:the pH for deposition is 8, impregnation concentration of H₂SO₄ is 0.5mol/L, impregnation time is 30min, calcination temperature and time are 550℃ and 4h, respectively. Under the optimal condition, solid superacid SO₄^2-/TiO₂-HZSM-5 catalyst has the best the catalytic performance, the esterification rate of trimethylolpropane oleate is as high as 97.6%, the product can exhibit excellent emulsification resistive property, and oil-water separation time is 5min. After solid superacid SO₄^2-/TiO₂-HZSM-5 catalyst is reused 6 times, the esterification rate of trimethylolpropane oleate decreases by 8.8%, i.e. the catalyst shows good reusability.

Key words: zeolite, catalyst, esterification, reactivity

摘要： 采用溶胶-凝胶法制备了HZSM-5分子筛负载SO₄^2-/TiO₂固体超强酸催化剂, 利用直接酯化法催化合成三羟甲基丙烷油酸酯。通过IR、XRD、BET、SEM对催化剂进行了表征, 结果表明TiO₂以纳米颗粒的形式附着于HZSM-5分子筛表面, 且负载后催化剂的比表面积高达309.2m²/g, 比HZSM-5分子筛提高了45.6m²/g, 且催化剂具有强酸性(-13.8< H₀ < -12.14)。探讨了沉淀pH值、焙烧温度、焙烧时间等催化剂制备条件对SO₄^2-/TiO₂-HZSM-5固体超强酸催化剂催化三羟甲基丙烷油酸酯酯化反应活性的影响。结果表明在沉淀pH=8、硫酸的浸渍浓度为0.5mol/L、浸渍时间为30min、焙烧温度为550℃、焙烧时间4h的条件下, SO₄^2-/TiO₂-HZSM-5固体超强酸催化剂催化活性最高, 三羟甲基丙烷油酸酯的酯化率高达97.6%;抗乳化性能良好, 油水分离时间为5min。SO₄^2-/TiO₂-HZSM-5固体超强酸催化剂在重复使用6次的情况下, 酯化率下降8.8%, 催化剂的重复使用性能良好。

关键词: 沸石, 催化剂, 酯化, 活性