La/CaO/MgO/Al_2O_3固体碱催化剂的制备及表征  

Preparation and characterization of La/CaO/MgO/Al_2O_3 solid base catalyst

作　　者：靳福全[1] 

机构地区：[1]太原工业学院化学与化工系,太原030008

出　　处：《中国油脂》2016年第11期52-56,共5页China Oils and Fats

基　　金：山西省高校科技开发项目(2010130);山西省高等学校大学生创新创业训练项目(2015449)

摘　　要：以镧、钙、镁、铝的硝酸盐为原料，以尿素为沉淀剂，采用均匀沉淀及高温焙烧的方法制备了La／CaO／MgO／Al2O3固体碱催化剂。采用单因素实验考察了制备条件对催化剂活性的影响，得到制备固体碱催化剂的优化工艺条件为：n（La）：n（Ca）：n（Mg）：n（Al）=0．0270：4：2：2，反应温度120qc，焙烧温度750℃，焙烧时间8h。将优化条件下制备的La／CaO／MgO／Al2O3固体碱用于催化蓖麻油和甲醇的酯交换反应，在n（醇）：n（油）：9：1、m（催化剂）：m（油）=0．04：1、搅拌速率550r／min、反应温度65℃、反应时间3h的条件下，蓖麻油转化率可达88．44％。采用Hammett指示剂法、TG、BET、XRD及SEM对催化剂及其前驱体进行了表征。结果表明：La／CaO／MgO／Al2O3固体碱的碱强度为7．2～11．2；当温度超过830℃时，La—Ca—Mg—Al水滑石的质量几乎不再随温度变化；催化剂比表面积为50．84m^2／g、孔容为0．1073cm^3／g，催化剂主要由CaO、MgO及Al2O33种晶体组成。With lanthanum nitrate, calcium nitrate, magnesium nitrate and aluminum nitrate as raw materials,urea as precipitation agent, La/CaO/MgO/Al2O3 solid base catalyst was prepared by homogeneous precipitation and high temperature calcination process. The effects of preparation conditions on the cata- lyst activity were investigated by single factor experiment, and the optimal preparation conditions were ob- tained as follows ： n （La） ： n （Ca） ： n （Mg） ： n （ Al ） = 0.027 0：4： 2： 2, reaction temperature 120 ℃, calcina- tion temperature 750 ℃, calcination time 8 h. Using La/CaO/MgO/Al2O3 solid base prepared under the optimal conditions as the catalyst for the transesterifieation of castor oil with methanol, the conversion rate of castor oil reached 88.44% under the conditions of n（methanol） ： n（oil） = 9： 1, m（catalyst） ： m（oil） = 0.04：1 ,stirring rate 550 r/rain,reaction temperature 65 ℃ and reaction time 3 h. The catalyst and its pre- cursor were characterized by Hammett indicator method, TG, BET, XRD and SEM. The results showed that the base strength of La/CaO/MgO/Al2O3 solid base was 7.2 - 11.2 ;the mass of the precursor La - Ca - Mg - Al hydrotaleite unchanged with temperature increasing when the temperature exceeded 830 ℃ ; the specific surface area and pore volume of the catalyst were 50.84 m^2/g and 0. 107 3 cm^3/g,respectively; the catalyst was mainly composed of three kinds of crystals of CaO, MgO and Al2O3.

关 键 词：固体碱 催化剂 制备 表征 

分 类 号：O643.36[理学—物理化学] TE667[理学—化学]