复合磁性LDHs的制备及其酯交换性能
发布时间：2018-11-17 18:19
【摘要】：随着世界的发展,化石燃料储备进一步枯竭,能源危机的出现及全球变暖、环境污染等问题迫使人类寻找可再生能源。人类的生存离不开大自然,由于资源的过度开采,导致环境问题日趋严重,保护环境迫在眉睫。生物柴油技术来源于大自然——可再生的植物、动物油等提取的油脂,经过化学反应制备的一种可以替代化石燃料的可再生能源。生物柴油是一种可再生能源,燃烧产物清洁无害,目前其生产方式为碱性条件下的酯交换反应,碱性催化剂在较为温和的条件下就可表现出较高的活性,但存在催化剂与产物分离困难,不利于其长期发展。(1)以FeCl3·6H_2O和FeCl2·4H_2O为原料(Fe3+、Fe2+摩尔比为2:1),制备磁性Fe_3O_4粒子,再以共沉淀法制备Fe_3O_4/MgAl-LDHs。在500℃下进行高温焙烧得到Fe_3O_4/Mg(Al)O磁性固体碱。通过热重(TG-DTG)、X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)、振动样品磁强计(VSM)对其晶体热稳定性、组成、结构、比表面积及磁学性能进行表征,并研究催化剂的酯交换活性。研究表明:MgAl-LDHs与Fe_3O_4形成一种复合物,具有类水滑石典型的层状结构,也有一定的磁响应能力,经500℃焙烧后生成了Fe_3O_4/MgAl-LDO,其比表面积显著增加,具有较高的酯交换活性。通过性能评价,在反应温度65℃,反应时间4h,n(甲醇):n(微藻油)=13:1,m(Fe_3O_4/MgAl-LDHs):m(微藻油)=4%的最优反应条件下,生物柴油产率达90%,具有重复利用性。(2)以共沉淀法制备Zn改性的Fe_3O_4/ZnMgAl-LDHs新型固体碱催化剂,通过热重(TG-DTG)、X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)、振动样品磁强计(VSM)对其进行表征。研究结果表明,当Zn2+的掺杂量为15%,n(甲醇):n(微藻油)=12:1,m(Fe_3O_4/ZnMg(Al)O):m(微藻油)=3%,65℃反应3h时,Fe_3O_4/ZnMgAl-LDHs催化活性最高,微藻新型生物柴油的收率高达94%,在重复使用7次后,生物柴油收率仍高于82%。
[Abstract]:With the development of the world, fossil fuel reserves have been depleted further, the emergence of energy crisis and global warming, environmental pollution and other problems forced people to look for renewable energy. The survival of human beings can not be separated from nature. Because of the over-exploitation of resources, environmental problems are becoming more and more serious, so it is urgent to protect the environment. Biodiesel technology comes from nature, renewable plant, animal oil, etc. It is a kind of renewable energy which can replace fossil fuel by chemical reaction. Biodiesel is a kind of renewable energy, and the combustion product is clean and harmless. At present, its production mode is transesterification under alkaline conditions, and the alkaline catalyst can exhibit higher activity under mild conditions. However, it is difficult to separate the catalyst from the product, which is not conducive to its long-term development. (1) Magnetic Fe_3O_4 particles were prepared by using FeCl3 6H_2O and FeCl2 4H_2O as raw materials (Fe3, Fe2 molar ratio was 2:1). Preparation of Fe_3O_4/MgAl-LDHs. by coprecipitation Fe_3O_4/Mg (Al) O magnetic solid base was obtained by calcination at 500 鈩，
本文编号：2338678
[Abstract]:With the development of the world, fossil fuel reserves have been depleted further, the emergence of energy crisis and global warming, environmental pollution and other problems forced people to look for renewable energy. The survival of human beings can not be separated from nature. Because of the over-exploitation of resources, environmental problems are becoming more and more serious, so it is urgent to protect the environment. Biodiesel technology comes from nature, renewable plant, animal oil, etc. It is a kind of renewable energy which can replace fossil fuel by chemical reaction. Biodiesel is a kind of renewable energy, and the combustion product is clean and harmless. At present, its production mode is transesterification under alkaline conditions, and the alkaline catalyst can exhibit higher activity under mild conditions. However, it is difficult to separate the catalyst from the product, which is not conducive to its long-term development. (1) Magnetic Fe_3O_4 particles were prepared by using FeCl3 6H_2O and FeCl2 4H_2O as raw materials (Fe3, Fe2 molar ratio was 2:1). Preparation of Fe_3O_4/MgAl-LDHs. by coprecipitation Fe_3O_4/Mg (Al) O magnetic solid base was obtained by calcination at 500 鈩，
本文编号：2338678
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