合成生物柴油用固体催化剂的制备与表征

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	合成生物柴油用固体催化剂的制备与表征
其他题名	Preparation and characterization of solid catalysts for biodiesel production
	刘畅
导师	袁振宏
	2009-05-31
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	硕士
学位专业	环境工程
关键词	生物柴油纳米磁性催化剂动力学
摘要	随着能源大量消耗以及环境的日益恶化，开发可替代石油的燃料，保护人类赖以生存的自然环境成了目前人类面临的严峻问题。生物柴油是一种可再生、可生物降解、无毒的清洁能源，受到世界各国青睐。目前，产业应用的生物柴油生产工艺为均相化学酸碱法，工艺较成熟，但存在短链醇用量大和环境污染等问题，后续处理也会增加成本，使得生物柴油整体生产成本增加，对比目前的石化能源成本并没有竞争力。本研究用沉淀法制备了一种新型纳米磁性固体碱催化剂，以替代传统均相化学酸碱法制备生物柴油。这种新型催化剂具备高效的催化活性和容易从反应体系中去除的特点，减少了生物柴油生产对环境的影响，并简化了生物柴油生产后续处理步骤，减少了投资成本和运行成本。通过离子交换法对阳离子树脂催化剂进行再生。利用级差分析法初步了解影响阳离子树脂催化剂再生的三个因素：再生时间，再生液浓度和再生温度对催化剂再生的影响。再生液温度对催化剂再生的影响最大，其次是再生液浓度，最后是再生时间。经过再生的阳离子树脂催化剂催化效率可以达到95.62%。对新型纳米磁性固体碱催化剂的磁性载体Fe3O4进行了研究，确定了磁性载体的性质以及制备条件。用沉淀法制备的Fe3O4平均粒径为17.433nm；磁化强度为79.319emu/g。通过透射电镜照片发现在常温下沉淀的Fe3O4磁性小球的粒径要略大于在温度为65℃条件下制备的Fe3O4，但是分散度较好。在800℃的煅烧条件下，负载的活性物质能够使Fe3O4磁性载体保持其超顺磁性，并且升温速率越小磁化强度越大。对催化剂负载的活性组分进行选择，确定负载CaO的催化剂催化活性最高。利用热重差热分析，研究纳米磁性固体碱催化剂前驱体在高温煅烧下的表现，确定活化催化剂的煅烧温度。对这种新型催化剂制备条件进行优化，确定以NaOH溶液作为沉淀剂以及活性组分的负载量为7:1时，此种催化剂的催化活性最高，催化速率最快，80 min后FAME转化率达到95%以上，最高可达98%。优化这种新型催化剂的反应条件。发现此种新型催化剂的最佳催化剂用量为2wt%，最佳醇油摩尔比为15:1，最佳反应温度为70℃。在这种条件下，FAME转化率最高，可达到98%。用X射线衍射分析对催化剂主要物相进行分析，发现在煅烧过程中CaO与Fe3O4发生了晶相转移，形成一种新型双金属复合氧化物—Ca2Fe2O5。利用氮气吸附法（BET），热场扫描电镜，震动样品磁强计分别对催化剂的比表面积，表面形态和超顺磁性进行表征。分析新型催化剂催化活性高的原因。并测试了此种催化剂的回收率以及寿命。发现在外加磁场的作用下，这种催化剂回收率可达到91.45%。经过五个批次后，磁性纳米固体碱催化剂催化反应的FAME转化率仍可达90%以上，第十个批次的FAME转化率还可达到70%以上。回收的催化剂X射线衍射谱图表明使用过的催化剂主要物相并没有发生明显的变化。最后通过非均相催化剂反应动力学的研究，建立了一种能够精确描述纳米磁性固体碱催化剂的反应的动力学方程，发现活化能为23.499 kJ/mol，反应速率方程为：为此种催化剂的后续研究积累数据。
其他摘要	As energy consuming and the environment deterioration, development of the fuel that can be substitute for petroleum and protection the surroundings that people depend on is a serious problem to the human beings. Biodiesel, a renewable, biodegradable, nontoxic fuel, is paid attention by countries in the world. Currently, the process have been used in industry of biodiesel is homogeneous acid-base method. This process is mature but the huge usage of methanol and environment pollution. It brings the problem of post-treatment of biodiesel and cost increasing. So, the increment cost of biodiesel abates the competitive power of biodiesel to the traditional petroleum. A new type of nanometer magnetic solid base catalyst has been prepared by precipitation method for preparation of biodiesel, which can be instead of acid-base method. This catalyst has good catalytic activity and can filter out from reactive system. It can simplify the post-treatment and decrease the pollution through the process. Furthermore, it reduces the cost of investment and running. Firstly, the ion-exchange method is taken advantage of regenerating action resin catalyst. Figure out the effect between regeneration efficiency and the three factors, regeneration time, regeneration temperature and the concentration of regenerable solution, by rank difference. The outcomes show that the factor of regeneration temperature is most influential. The next is the concentration of regenerable solution. The effect of regeneration time is most effectless. The catalytic activity of renewable action resin can reach 95.62% of new catalyst. Secondly, via researching the magnetic supporter Fe3O4 of the new type of nanometer magnetic solid base catalyst, to determine conditions of preparation and characters of the magnetic supporter. The results show that the average grain diameter of Fe3O4 prepared by precipitation is 17.433nm, and magnetization is 79.319emu/g. Though the average grain diameter of Fe3O4 precipitated at room temperature is bigger than that of Fe3O4 precipitated at 65℃, the dispersivity of Fe3O4 precipitated at room temperature is better. At the condition of 800℃, the catalytic activity material loaded on the surface of Fe3O4 can protect the superparamagnetism of magnetic supporter. And the smaller the heating rate is, the higher the superparamagnetism is. Thirdly, choosing the loaded catalytic activity material, and find out that the catalytic activity is the highest when CaO loaded on it. The performance of nanometer magnetic solid base catalyst precursor calcined at high temperature is researched by thermogravimetry differential thermal analysis, and calcine temperature that activate catalyst is defined. Optimize the conditions of catalyst preparation, discover that under the conditions of proportion of CaO and Fe3O4 supporter is 7:1, precipitation with NaOH, the catalytic activity is the highest and the catalytic rate is fastest: the rate of transesterification is above 95% within 80 min and can reach 98% ultimately. Optimize the conditions of the transesterification reaction catalyzed by this new magnetic catalyst. figure out that the best conditions is that methanol to oil mo1ar ratio of 15 and the catalyst dosage of 2% to oil at 70 ℃, the biodiesel yield reaches to 95% in 80 min, even to 98% finally. Analyze the main crystalling phase of the catalyst by x-ray diffraction analysis, Ca2Fe2O5, a kind of new metal multiple oxide, was formed during the process of calcining. Characterize the specific surface area, surface morphology and superparamagnetism by BET, SEM, VSM, and find out the reasons that high catalytic activity of the new type catalyst. Measure the recovery rate and the catalytic life of the catalyst, and the results illustrate that the recovery rate is 91.45% separated by additional magnetic field; after 5 reactions, the transesterification rate is still above 90%. After 10 times used, the transesterification rate is above 70%. The main crystalling phase of used catalyst is not obviously changed analized by x-ray diffraction. At the last, through the heterogeneous catalyst reaction kinetics analysis, a kinetic equation that can precisely describes reaction catalyzed by nanometer magnetic solid base catalyst is established. The activation is 23.499 kJ/mol, and the reaction rate equation is: . It accumulates data for the post research of this new type catalyst.
页数	75
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/4027
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	刘畅. 合成生物柴油用固体催化剂的制备与表征[D]. 广州能源研究所. 中国科学院广州能源研究所,2009.

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