纳米固体碱催化制备生物柴油的研究

发布时间：2018-03-11 17:03

  本文选题：纳米固体碱　切入点：催化　出处：《西安石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文通过浸渍法和共混法制备KF/γ-Al_2O_3催化剂,以其作为催化剂,考察其在催化油脂-碳酸二甲酯-甲醇连续双酯交换体系制备生物柴油中的催化性能。结果表明,共混法制备的纳米催化剂KF/γ-Al_2O_3具有更高的催化活性。在油/酯/醇摩尔比为1/1/8,催化剂用量5%,反应时间30min,生物柴油产率可达98.82%,比相同反应条件下浸渍法制备的KF/γ-Al_2O_3催化效果提高40%。与传统甲醇-油脂酯交换制备生物柴油体系相比,该体系达到98%生物柴油产率所需时间缩短近40min。采用TGA、BET、CO_2-TPD和IR对催化剂进行表征,结果表明KF/γ-Al_2O_3催化剂具有高活性的主要原因是焙烧过程中得到新的强碱性位点K2O,极大地提高了催化剂的碱性强度。实验还通过溶胶-凝胶法制备了一系列纳米碱金属氧化物催化剂,分别考察该类固体碱在催化油脂-碳酸二甲酯-甲醇连续双酯交换反应体系制备生物柴油中的反应性能。结果表明,纳米级别氧化物催化效果明显优于普通固体碱,其中,纳米CaO表现出良好的催化活性。在油/酯/醇摩尔比1/1/8,催化剂用量5%,反应4h生物柴油产率最高为92.82%,比普通氧化钙在相同反应条件下产率提高25%。采用TGA、BET、CO_2-TPD和IR对催化剂进行表征,结果表明,溶胶-凝胶法制备纳米氧化物过程中并未形成新晶相,但CaO的结晶度提高,且催化剂的比表面积、孔径和孔体积都明显增大,说明在该反应中,催化剂的表面结构是影响其催化效果的重要因素。采用共沉淀法制备不同纳米复合型固体碱,分别考察该类固体碱在催化油脂-碳酸二甲酯-甲醇连续双酯交换反应体系制备生物柴油中的反应性能。实验结果表明,纳米复合碱MgO-CaO具有良好的催化效果。油/酯/醇摩尔比1/1/6,催化剂用量10%,反应4h生物柴油产率最高为97.39%。采用TGA、BET、CO_2-TPD和IR对催化剂进行表征,结果表明,焙烧温度对MgO-CaO粉末的晶相形貌基本无影响,但对催化剂表面结构和催化活性的影响非常大,800℃焙烧得到的纳米MgO-CaO比表面积、孔径和孔体积最大,催化剂上MgO和CaO分布均匀。论文中还通过反向沉淀法制备纳米氢氧化钙,焙烧后得到其衍生物纳米氧化钙,并以此为催化剂考察其催化油脂-碳酸二甲酯-甲醇连续双酯交换反应体系制备生物柴油的性能。实验结果表明,以纳米氢氧化钙为前躯体制备的纳米氧化钙催化活性较高,油/酯/醇摩尔比1/1/8,催化剂用量10%,反应1h生物柴油产率最高为94.24%,比相同条件下普通氧化钙产率提高40%,比溶胶-凝胶法纳米氧化钙反应时间缩短3h。采用TGA、BET、CO_2-TPD和IR对催化剂进行表征,结果表明,不同于溶胶-凝胶法,焙烧温度对该催化剂表面结构几乎无影响,而是通过改变催化剂的表面碱度和活性位点数量来影响催化剂活性。
[Abstract]:In this paper, KF/ 纬 -Al _ 2O _ 3 catalyst was prepared by impregnation method and blending method. The catalyst was used as catalyst to study the catalytic performance of KF/ 纬 -Al _ 2O _ 3 catalyst in the continuous transesterification system of lipide-dimethyl carbonate and methanol to prepare biodiesel. The nanocatalyst KF/ 纬 -Al _ 2O _ 3 prepared by blending method has higher catalytic activity. When the molar ratio of oil / ester / alcohol is 1 / 1 / 8, the amount of catalyst is 5 and the reaction time is 30 min, the biodiesel yield can reach 98.82%, which is higher than that of KF/ 纬 -Al _ 2O _ 3 prepared by impregnation under the same reaction conditions. Compared with the traditional methanol-oil ester exchange system, the biodiesel system was prepared. The time required for the system to reach 98% biodiesel yield was shortened by 40 mins. The catalyst was characterized by TGABETCO _ 2-TPD and IR. The results show that the main reason for the high activity of KF/ 纬 -Al _ 2O _ 3 catalyst is that the new strong basic site K _ 2O _ 2 is obtained during the calcination process, which greatly improves the basic strength of the catalyst. A series of nanometer alkali gold was prepared by sol-gel method. Of oxide catalysts, The catalytic properties of these solid bases in the continuous transesterification of oil, dimethyl carbonate and methanol to biodiesel were investigated. The results showed that the catalytic effect of nanometer oxide was better than that of ordinary solid bases. Nanometer CaO showed good catalytic activity. When the molar ratio of oil / ester / alcohol was 1 / 1 / 8, the amount of catalyst was 5%, the highest yield of biodiesel was 92.82% after 4 h reaction, which was 25% higher than that of ordinary calcium oxide under the same reaction conditions. The catalyst was characterized by TGABETT CO 2-TPD and IR. The results showed that no new crystalline phase was formed in the preparation of nano-oxide by sol-gel method, but the crystallinity of CaO was increased, and the specific surface area, pore size and pore volume of the catalyst were increased obviously. The surface structure of the catalyst is an important factor affecting its catalytic effect. Different nanometer composite solid bases were prepared by coprecipitation method. The reaction performance of this kind of solid base in the continuous transesterification of oil, dimethyl carbonate and methanol to biodiesel was investigated. Nanometer composite base MgO-CaO has good catalytic effect, the molar ratio of oil to ester / alcohol is 1 / 1 / 6, the amount of catalyst is 10, the highest yield of biodiesel is 97.39% for 4 h. The catalyst is characterized by TGABETCO2-TPD and IR. The calcination temperature had no effect on the crystal morphology of MgO-CaO powder, but the effect on the surface structure and catalytic activity of the catalyst was very great. The specific surface area, pore size and pore volume of nano-sized MgO-CaO calcined at 800 鈩，

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