【作者】 王伟；

【导师】 王运；

【作者基本信息】 华中农业大学 ， 农药学， 2015， 硕士

【摘要】 随着化石燃料的逐渐枯竭、环境问题的日益凸显,生物柴油作为一种清洁、可再生的生物质能源已成为世界各国关注的焦点。非均相固体碱催化剂可以使生物柴油的工业化生产过程更加“绿色化”,制备出廉价、高效的固体碱催化剂对于生物柴油的规模化生产具有重要意义。本文制备了两种钙基固体碱催化剂用于催化菜籽油合成生物柴油,并采用多种现代技术手段对催化剂进行表征。主要研究结果如下:1.用KF浸渍Ca O-La2O3制备了具有高催化活性的KF/Ca O-La2O3催化剂。KF/Ca O-La2O3催化剂最佳制备条件为:La2O3的添加量为15 wt%,煅烧温度为600℃,煅烧时间为3h。用XRD、低温N2吸附-脱附、SEM、TEM以及Hammett指示剂法表征了催化剂的晶相结构、形貌以及碱强度。煅烧后的催化剂的主要晶相是Ca O、KCa F3和La OF,优化条件下制备的催化剂呈圆球状,催化剂有一定的团聚,可以清晰的看到其多孔结构,催化剂比表面积为0.96m2/g,孔体积为0.0057cm3/g,平均孔径为24.7nm,催化剂的碱强度为15.0<H—<18.4。优化了催化剂用于酯交换反应的条件,在温度为65℃,催化剂用量为4 wt%,醇油摩尔比为12:1的条件下,反应80min,FAME产率可达97.3%。KF/Ca O-La2O3重复使用5次后产率仍可达70%以上。2.浸渍法制备了KF/Ca O-MSP催化剂。用XRD、低温N2吸附-脱附、SEM、TEM以及Hammett指示剂法表征了催化剂的晶相结构、形貌以及碱强度。煅烧后的催化剂的主要晶相是Ca O、KCa F3和KCa CO3F,优化条件下制备的催化剂可明显观察到其多孔结构,催化剂比表面积为1.04m2/g,孔体积为0.0048cm3/g,平均孔径为18.5nm,催化剂的碱强度为9.8<H—<15.0。在优化制备条件后的催化剂在温度为65℃,催化剂用量为4 wt%,醇油摩尔比为12:1,反应时间为150min的条件下,FAME产率可达95.3%。3.通过对KF/Ca O-La2O3和KF/Ca O-MSP两种催化剂制备过程的研究,发现KF/Ca O-La2O3在催化酯交换反应前后形态几乎未发生改变,表现出良好的机械强度;而KF/Ca O-MSP呈粉状,易碎,强度明显较差。同时对KF/Ca O-La2O3和Ca O进行了机械强度比较,发现KF/Ca O-La2O3催化剂极限正压力均值25.2Kg,Weibull模量m为6.37,说明KF/Ca O-La2O3不仅有较高的强度,而且具有较高的强度可靠性,在生物柴油领域有较好的应用前景。4.通过研究发现,负载KF的钙基催化剂中产生的新晶相KCa F3不是活性晶相,不能催化油脂与甲醇的酯交换反应。更多还原

【Abstract】 With the gradual depletion of fossil fuels, environmental issues have become increasingly prominent, biodiesel that is a clean, renewable biomass energy has received extensive attention all over the world. Heterogeneous catalysts could make the production of biodiesel more environmentally friendly, and it will have important significance to prepare cheap heterogeneous catalysts with good performance for biodiesel production. In this research, two kinds of calcium oxide based solid base catalyst were prepared for synthesis of biodiesel from rapeseed oil, and the catalysts were characterized using a variety of modern characterization methods. The major results of this thesis were summarized as follows:1. A high catalytic activity catalyst KF/Ca O-La2O3 was prepared by impregnation method. The optimum preparation conditions of KF/Ca O-La2O3 are as follows: La2O3 additive amount 15 wt%, calcination temperature 600℃ and calcination time 3h. The crystal structure and morphology of the catalyst were characterized by XRD, N2 adsorption-desorption, SEM and TEM, and base strength was characterized by Hammett indicator method. Characterization showed: Ca O, KCa F3 and La OF were formed after calcination; the porous structure can be observed; BET surface area was 0.96m2/g, average pore size was 24.7nm; the hammett base strength was 15.0<H—<18.4. The effects of reaction conditions were investigated, and results indicate that when transesterification carried out at temperature 65℃ with a molar ratio of oil to methanol 12:1 and a catalyst dosage 4 wt% for 80 min, the highest FAME yield 97.3% could be achieved. The KF/Ca O-La2O3 can be separated from the product for reuse, and the FMAE yield was more 70% after reused of 5 times.2. KF/Ca O-MSP catalyst was prepared by impregnation method. The optimum preparation conditions of KF/Ca O-La2O3 are as follows: La2O3 additive amount 15 wt%, calcination temperature 600℃ and calcination time 3h. The crystal structure and morphology of the catalyst were characterized by XRD, N2 adsorption-desorption, SEM and TEM, and base strength was characterized by Hammett indicator method. Characterization showed: Ca O, KCa F3 and La OF were formed after calcination; the porous structure can be observed; BET surface area was 1.04m2/g, average pore size was 18.5nm; the hammett base strength was 9.8<H—<15.0. Under the optimum reaction conditions:reaction temperature 65℃, a molar ratio of oil to methanol 12:1, catalyst dosage 4 wt% and reaction time 2.5h, the highest FAME yield 95.3% could be achieved.3. In our research, between KF/Ca O-La2O3 and KF/Ca O-MSP, only KF/Ca O-La2O3 maintain the integrity of shape after transesterification reaction. Mechanical strength tests showed that the mechanical strength of KF/Ca O-La2O3 improved significantly compared with pure Ca O, and the experimental data follows well with the Weibull distribution. The average limited pressure of cylindrical KF/Ca O-La2O3 catalyst was 25.2Kg, and the Weibull modulus m was 6.37, which indicated that KF/Ca O-La2O3 has good mechanical strength performance with high strength reliability.4. Our research showed that the new crystal KCa F3 formed after calcium oxide based solid base catalyst loaded with KF was not an active crystal, which can not catalyze the transesterification reaction of oil and methanol.更多还原