CaO/Zn-Al-O固体碱的制备、表征及其催化活性

采用共沉淀、浸渍及高温焙烧的方法制备了CaO/Zn-Al-O固体碱催化剂。采用正交试验考察了制备条件对CaO/Zn-Al-O固体碱油脂醇解催化活性的影响,得到的优化条件为:一次焙烧时间0h、二次焙烧温度750℃、二次焙烧时间3h。以优化条件下制备的CaO/Zn-Al-O固体碱为催化剂,在n(醇)/n(油)=9、m(催化剂)/m(油)=0.04、搅拌速率400r/min、反应温度70℃、反应时间4h的条件下,菜籽油转化率可达96.3%。采用TGDTA、BET、XRD、SEM技术及Hammett指示剂法对催化剂及其前驱体进行了表征。对催化剂结构及表面性质与其活性之间的关系进行了讨论。

Preparation and Characterization of CaO/Zn-Al-O Solid Base and Its Catalytic Activity

CaO/Zn-Al-O solid base catalyst was prepared using coprecipitation,impregnation and calcination method.Effects of preparation conditions on the catalytic activity of CaO/Zn-Al-O solid base in oil alcoholysis were investigated through orthogonal experiments.Optimized conditions obtained were as follows：the first calcination time of 0 h,the second calcination temperature of 750 ℃,the second calcination time of 3 h.When the reaction was carried out at 70 ℃ for 4 h with alcohol/oil molar ratio of 9,catalyst/oil mass ratio of 0.04,stirring speed of 400 r/min,rapeseed oil conversion arrived at 96.3% in the presence of the CaO/Zn-Al-O catalyst prepared at optimal conditions.The catalyst and its precursor were characterized using TG-DTA,BET,XRD,SEM and Hammett indicator method.Relationship between the structure and the surface properties of the catalyst and its activity was discussed.