生物质催化氧化产物甲酸的分离研究

发布时间：2018-04-02 16:12

本文选题：生物质　切入点：甲酸　出处：《北京化工大学》2015年硕士论文

【摘要】：近年来,以生物质为原料制备高附加值化学品得到了越来越广泛的关注,其中在生物质催化氧化制甲酸(FA)方面取得了一些进展,但有关生物质催化氧化产物中甲酸的有效分离方法还未见报道。本文针对在高温水中使用NaVO3-H2SO4催化氧化体系转化生物质后的产物中的甲酸的分离进行了研究,主要研究了不同物理萃取剂和化学萃取剂N,N-二丁基甲酰胺(DBF)对甲酸水溶液的液-液萃取过程,并比较了两类萃取剂对甲酸的萃取规律,最后对萃取剂DBF的再生进行了研究,为适合产物体系中甲酸分离的萃取剂的筛选提供了一些依据,主要结论如下：1.比较了两类萃取剂对甲酸萃取效果。结果表明对低浓度的甲酸溶液,DBF的萃取效果要明显优于常规的物理萃取剂,当甲酸浓度为5 wt%时,物理萃取剂的萃取分配系数K普遍小于1,而DBF萃取分配系数接近于3。2.考察了甲酸初始浓度和催化剂体系等因素对萃取过程的影响,并比较了两类萃取剂的萃取机制。结果表明物理萃取剂对甲酸的萃取主要利用组分之间的作用力,化学萃取剂DBF主要利用可逆络合反应；物理萃取的推动力为甲酸的浓度,而化学萃取推动力为可逆反应平衡；催化剂体系对萃取过程有一定的影响,H2SO4的加入能提高萃取分配系数,而NaV03起相反作用；实验中也发现DBF能萃取极少量的V02+。3.利用质量作用定律对DBF萃取甲酸的可逆络合反应平衡进行了研究,建立了萃取平衡模型,通过对平衡常数KE的计算表明DBF与甲酸之间按化学计量比1：1形成络合物,且该可逆过程为一放热反应,同时计算了可逆反应过程的表观焓变和熵变：ΔH=-6.3 kJ·mol-1; △S=-23 J·mol-1K-1。4.考察了减压蒸馏对萃取剂DBF的再生的效果,结果表明可以通过两步减压蒸馏首先蒸出大部分水然后蒸出大部分甲酸来实现DBF的再生和甲酸的回收；另外考察了NaOH溶液、固体CaO两种反萃剂对DBF的再生效果,发现固体CaO要比NaOH溶液更加适合用作反萃剂。
[Abstract]:In recent years, more and more attention has been paid to the preparation of high value-added chemicals from biomass, among which some progress has been made in the catalytic oxidation of biomass to formate.However, the effective separation methods of formic acid in biomass catalytic oxidation products have not been reported.In this paper, the separation of formic acid from biomass products by using NaVO3-H2SO4 catalytic oxidation system in high temperature water was studied.The liquid-liquid extraction process of formic acid aqueous solution with different physical extractants and chemical extractants NN- di#china_person0# formamide was studied, and the extraction laws of two kinds of extractants for formic acid were compared. Finally, the regeneration of extractant DBF was studied.Some evidences are provided for the selection of extractants suitable for the separation of formic acid in the product system. The main conclusions are as follows: 1.The extraction effects of two kinds of extractants for formic acid were compared.The results showed that the extraction efficiency of low concentration formic acid solution was obviously better than that of conventional physical extractant. When the concentration of formic acid was 5 wt%, the extraction partition coefficient K of physical extractant was less than 1, and the extraction partition coefficient of DBF was close to 3.2.The effects of the initial concentration of formic acid and the catalyst system on the extraction process were investigated, and the extraction mechanisms of the two extractants were compared.The results show that the extraction of formic acid by physical extractant mainly uses the force between components, the chemical extractant DBF mainly uses reversible complexation reaction, the driving force of physical extraction is the concentration of formic acid, and the driving force of chemical extraction is reversible reaction equilibrium.The addition of H _ 2SO _ 4 can increase the extraction partition coefficient, but NaV03 has the opposite effect, and it is also found that DBF can extract a very small amount of V _ (02. 3).The reversible complexation equilibrium of formic acid extracted by DBF was studied by using the law of mass action. The equilibrium model of extraction was established. The calculation of the equilibrium constant Ke showed that the complex formed between DBF and formic acid at 1:1 according to stoichiometric ratio.The reversible process is an exothermic reaction. The apparent enthalpy and entropy of the reversible reaction are calculated as follows: 螖 H ~ (3 +) -6.3 kJ mol ~ (-1), S ~ (23) J mol ~ (-1) K ~ (-1.4).The effect of vacuum distillation on the regeneration of extractant DBF was investigated. The results showed that the regeneration and recovery of DBF and formic acid could be realized by two-step vacuum distillation first by distilling most of water and then by distilling most formic acid, and the solution of NaOH was also investigated.It is found that solid CaO is more suitable than NaOH solution for the regeneration of DBF by two kinds of stripping agents.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.32;TQ225.121;TK6

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