甲醇供氢与油脂一步反应制备脂肪醇的路径及机理研究

发布时间：2018-02-27 12:13

本文关键词： 脂肪醇油脂选择性加氢甲醇供氢 Cu/SiO_2催化剂　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：脂肪醇是一种广泛应用、大规模生产的化学品,主要应用于洗涤剂、润滑剂、化妆品、个人护理产品、药物,以及在化妆品和食品工业中用作润滑基质、软化剂和增稠剂,在塑料产业中用为聚合剂。以天然油脂为原料制备天然脂肪醇的传统方法通常为两步法,存在着操作繁琐、设备复杂、反应条件苛刻、需要消耗大量的氢气等问题。为了解决目前使用的工艺存在的弊端,我们设计了一种全新的制备脂肪醇的方法,即在无氢条件下一锅法实现甲醇和油脂共活化的路线,利用甲醇原位生成的氢气供给给油脂进行选择性加氢生成脂肪醇。我们从甲醇脱氢反应入手,设计了一种能有效促进甲醇原位产氢的Cu基催化剂(由沉积沉淀法制备,氨水为沉淀剂),确定了催化剂的载体以及温度等因素对该反应的影响。通过对催化剂的一系列表征,结合分析气液相反应产物,得出了甲醇脱氢反应机理,得到了纯度高达87%的氢气,且副产物CO较少,仅有12%,少量的CO不易毒化金属活性组分致使催化剂失活。随后,我们进一步耦合甲醇脱氢反应与脂肪酸甲酯加氢反应,考察了水热法制备的Cu/SiO_2催化剂在该反应体系下的催化活性,确定了能够原位产生的氢气在反应体系内部转移的反应机理,最后在一锅法中实现了无氢条件下由油脂与甲醇这两种生物质共活化生成脂肪醇的过程。通过分析确定了催化剂中的Cu2O和Cu0两种铜组分共同组成催化甲醇脱氢反应的活性组分,Cu0则是加氢反应的活性中心。结合气液相反应产物,我们还提出了该反应过程的催化路径。综上,我们开发了一种全新的一锅法由油脂制备脂肪醇的方法,即在Cu/SiO_2催化剂的作用下,将甲醇原位生成的氢气供给给由油脂与甲醇反应生成的脂肪酸甲酯进行选择性加氢,生成高选择性的脂肪醇。在本课题工作中,我们设计了一种既能催化甲醇脱氢、又能催化脂肪酸甲酯选择性加氢过程的Cu基催化剂,同时阐明了这两个单独过程及耦合后整个过程的反应机理。这种方法简单高效,原子经济性高,且符合绿色化学及化工过程的定义,所制备的高品质脂肪醇也更为清洁绿色。
[Abstract]:Fatty alcohol is a widely used, mass-produced chemical that is mainly used in detergents, lubricants, cosmetics, personal care products, medicines, and in the cosmetics and food industries as a lubricant, softener and thickener, The traditional method of preparing natural fatty alcohol from natural oil is usually two-step method, which has complicated operation, complicated equipment and harsh reaction conditions. In order to solve the disadvantages of the current process, we have designed a new method for the preparation of fatty alcohols, that is, the one-pot method to realize the co-activation of methanol and oil under the condition of no hydrogen. Fatty alcohols were prepared by selective hydrogenation of oil with hydrogen from methanol in situ. Based on the dehydrogenation of methanol, a Cu-based catalyst was designed to effectively promote in situ hydrogen production from methanol. The influence of catalyst carrier and temperature on the reaction was determined. The mechanism of methanol dehydrogenation was obtained by a series of characterization of catalyst and analysis of the products of gas-liquid phase reaction. Hydrogen with purity as high as 87% was obtained, and the by-product CO was only 12%. The catalyst was deactivated by a small amount of CO not easily toxic to metal active components. Subsequently, we further coupled the methanol dehydrogenation reaction with the hydrogenation of fatty acid methyl ester. The catalytic activity of Cu/SiO_2 catalyst prepared by hydrothermal method in this reaction system was investigated, and the mechanism of hydrogen transfer in situ was determined. Finally, fatty alcohols were co-activated by two kinds of biomass, oil and methanol, in a one-pot process. The two copper components of Cu2O and Cu0 in the catalyst were determined to constitute the reverse reaction of methanol dehydrogenation. The active component Cu0 is the active center of hydrogenation reaction. In summary, we have developed a novel one-pot method for the preparation of fatty alcohols from oils, that is, in the presence of Cu/SiO_2 catalysts. The hydrogen produced in situ from methanol was supplied to the fatty acid methyl ester from the reaction of oil and methanol for selective hydrogenation to produce a high selectivity fatty alcohol. In this work, we designed a kind of catalyst for the dehydrogenation of methanol. Cu-based catalyst can also catalyze selective hydrogenation of fatty acid methyl ester. The reaction mechanism of these two separate processes and the whole process after coupling are also explained. This method is simple and efficient, and has high atomic economy. In accordance with the definition of green chemistry and chemical process, the high quality fatty alcohol prepared is cleaner and greener.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ223

【参考文献】