發(fā)布時間：2018-04-02 16:12

  本文選題：生物質(zhì)　切入點：甲酸　出處：《北京化工大學(xué)》2015年碩士論文

【摘要】：近年來,以生物質(zhì)為原料制備高附加值化學(xué)品得到了越來越廣泛的關(guān)注,其中在生物質(zhì)催化氧化制甲酸(FA)方面取得了一些進展,但有關(guān)生物質(zhì)催化氧化產(chǎn)物中甲酸的有效分離方法還未見報道。本文針對在高溫水中使用NaVO3-H2SO4催化氧化體系轉(zhuǎn)化生物質(zhì)后的產(chǎn)物中的甲酸的分離進行了研究,主要研究了不同物理萃取劑和化學(xué)萃取劑N,N-二丁基甲酰胺(DBF)對甲酸水溶液的液-液萃取過程,并比較了兩類萃取劑對甲酸的萃取規(guī)律,最后對萃取劑DBF的再生進行了研究,為適合產(chǎn)物體系中甲酸分離的萃取劑的篩選提供了一些依據(jù),主要結(jié)論如下：1.比較了兩類萃取劑對甲酸萃取效果。結(jié)果表明對低濃度的甲酸溶液,DBF的萃取效果要明顯優(yōu)于常規(guī)的物理萃取劑,當(dāng)甲酸濃度為5 wt%時,物理萃取劑的萃取分配系數(shù)K普遍小于1,而DBF萃取分配系數(shù)接近于3。2.考察了甲酸初始濃度和催化劑體系等因素對萃取過程的影響,并比較了兩類萃取劑的萃取機制。結(jié)果表明物理萃取劑對甲酸的萃取主要利用組分之間的作用力,化學(xué)萃取劑DBF主要利用可逆絡(luò)合反應(yīng)；物理萃取的推動力為甲酸的濃度,而化學(xué)萃取推動力為可逆反應(yīng)平衡；催化劑體系對萃取過程有一定的影響,H2SO4的加入能提高萃取分配系數(shù),而NaV03起相反作用；實驗中也發(fā)現(xiàn)DBF能萃取極少量的V02+。3.利用質(zhì)量作用定律對DBF萃取甲酸的可逆絡(luò)合反應(yīng)平衡進行了研究,建立了萃取平衡模型,通過對平衡常數(shù)KE的計算表明DBF與甲酸之間按化學(xué)計量比1：1形成絡(luò)合物,且該可逆過程為一放熱反應(yīng),同時計算了可逆反應(yīng)過程的表觀焓變和熵變：ΔH=-6.3 kJ·mol-1; △S=-23 J·mol-1K-1。4.考察了減壓蒸餾對萃取劑DBF的再生的效果,結(jié)果表明可以通過兩步減壓蒸餾首先蒸出大部分水然后蒸出大部分甲酸來實現(xiàn)DBF的再生和甲酸的回收；另外考察了NaOH溶液、固體CaO兩種反萃劑對DBF的再生效果,發(fā)現(xiàn)固體CaO要比NaOH溶液更加適合用作反萃劑。
[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.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ028.32;TQ225.121;TK6

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本文編號：1701146