本文選題：催化膜 + 滲透汽化��； 參考：《北京化工大學》2015年博士論文

【摘要】：平衡反應是自然界中的常見現象,它限制了化學反應在給定溫度、壓力、濃度、配比等條件下的最大轉化率,在有機液相化學反應如酯化、硝化、縮酮、�；然瘜W工業(yè)中的重要反應中尤為常見。同時,這類反應還多存在產物或原料的熱穩(wěn)定性差、副反應多、連串反應等問題。如何有效地提高這類反應的產率并進而提高其原料利用率、減輕后續(xù)分離過程的能耗是困擾有機化工生產的一個重要難題。本文提出采用浸沒沉淀相轉化法制備一種具有反應-分離雙功能的,類似于“三明治復合結構”的,具有疏松多孔催化層的復合活性催化膜,構筑了一種新型的多功能反應器——活性滲透汽化膜反應器,用于有機液相平衡反應的研究�！叭髦巍睆秃辖Y構為：頂層為疏松多孔的聚乙烯醇(Polyvinyl alcohol, PVA)催化層,其中通過相轉化法將催化劑(固體酸,生物酶等)固定；中間為致密的選擇性分離層,膜材料同樣為PVA；底層為多孔聚醚砜(Polyethersulfone, PES)支撐層,起到機械支持作用。通過對復合膜結構尤其是催化層多孔結構的制備和優(yōu)化,系統(tǒng)考察了催化層的催化活性,并通過丁醇水的脫除實驗,研究了復合活性催化膜的分離特性,最后用乙酸／正丁醇合成乙酸正丁酯的反應為探針,考察了不同操作條件下該反應在多孔催化層CAMR (Catalytically Active Membrane Reactor)中反應和分離的特性,并通過與傳統(tǒng)IMR (Inert Membrane Reactor)和致密催化層CAMR對比,探討了膜反應器內不同組分隨時間變化規(guī)律,研究其傳質行為的特點和規(guī)律,嘗試分析了活性膜反應器耦合強化機理,證明本文所制備的復合催化膜能進一步強化對反應轉化率的提升,進而進一步提高原料的時空轉化率。最后將本文提出的浸沒沉淀相轉化法制備復合催化膜拓展到固體催化體系和生物催化體系,表面該方法具有一定的通用性。對于制備純PVA多孔膜和多孔催化膜,PVA濃度對成膜結構有較大影響,在PVA濃度為5wt.%時,形成膠粒狀結構,而當PVA濃度為10wt.%時,形成封閉的胞腔或蜂巢狀結構。凝固浴溫度升高,有利于縮短成膜時間。在制備多孔催化膜時,催化劑濃度在10wt.%較為合適,催化劑濃度進一步升高,趨向于形成致密皮層,不利于成膜的多孔性。不同催化劑對探針反應的催化活性順序為：致密催化層≈膠粒狀催化層(PVA濃度5wt.%)游離催化劑胞腔狀催化層(PVA濃度10wt.%)無催化劑。利用取得到動力學數據建立了擬均相模型,模型預測結果與實驗值吻合良好。通過丁醇水的滲透汽化脫水實驗,致密催化層CAMR中由于催化層為致密結構且膜厚較大,所以通量最小,組分擴散阻力最大,而在多孔催化層CAMR中由于催化層為疏松多孔結構,其通量較大,說明多孔結構有利于降低組分的傳質阻力,不僅能改善反應物向催化位點的擴散,同時能夠提高產物向膜后側的傳遞,從而提高水的原位脫除作用,有利于實現真正的“原位”脫除。在反應-分離耦合強化實驗中,在IMR,致密催化層CAMR和多孔催化層CAMR中,乙酸和正丁醇隨時間同步減小,乙酸正丁酯和水在剛開始階段同步上升,但一段時間之后,水的濃度變化與乙酸正丁酯的濃度曲線發(fā)生偏離,由于水的脫除速率大于水的生成速率,在膜反應器內水的濃度曲線出現拐點,逐漸隨時間下降。提高溫度能進一步提高乙酸的轉化率�？偼康淖兓瑯佑袃蓚�階段：在反應前期,通量先逐漸升高,達到拐點后逐漸下降。在85℃時,在多孔催化層CAMR中,前側水濃度在28h時將為0,此后在膜反應器內不能檢測到水,但后側通量表明此時反應不斷進行,水不斷的脫除。說明在此時間以后,產物實現了真正的原位脫除作用,即生成一分子水,立即向膜下游側擴散從而脫除。這種效果隨著催化劑負載量減小更明顯,在催化劑負載量將為2.25g/L時,前側水濃度在23.5h即為O。說明實現真正原位脫除的關鍵在于合理調節(jié)催化膜的催化性能和分離性能。通過IMR和多孔催化層CAMR的對比,證明本文制備的復合催化膜能夠進一步實現過程強化,由于水在膜表面生成,水的推動力更大,使得水的通量更大,最終表現在乙酸的轉化率要更高。在約35.5 h時,IMR中乙酸轉化率僅約75%,而在多孔催化層CAMR中,乙酸轉化率達到約85%。而在致密催化層CAMR和多孔催化層CAMR對比中,由于多孔催化層傳質阻力更低的優(yōu)點,水的生成速率和脫除速率均更快,反應轉化率更高。本文提出的利用浸沒沉淀相轉化法制備具有多孔催化層的復合催化膜的方法具有一定通用性。IER/PVA/PES復合催化膜同樣能實現對水的原位移除,實現轉化率的強化,并且膜結構在使用前后并未發(fā)生明顯變化。而Lipase/PVA/PES復合催化膜能保持酶的生物活性,同時也能實現轉化率的進一步強化。
[Abstract]:Equilibrium reaction is a common phenomenon in nature, which restricts the maximum conversion of chemical reactions at a given temperature, pressure, concentration, ratio and other conditions. It is particularly common in chemical reactions such as esterification, nitrification, ketone, acylation, etc. in organic liquid chemical reactions. It is an important problem in organic chemical production that how to effectively improve the yield of this kind of reaction and improve the utilization of raw materials and reduce the energy consumption in the subsequent separation process. Sandwich composite structure, a composite active catalytic membrane with loose porous catalytic layer, constructed a new multi-functional reactor, active pervaporation membrane reactor, used in the study of organic liquid equilibrium reaction. The sandwich composite structure is that the top layer is loose porous polyvinyl alcohol (Polyvinyl alcohol, PVA) catalysis The layer, in which the catalyst (solid acid, biological enzyme, etc.) is fixed by phase transformation, the intermediate is dense and selective separation layer, the membrane material is PVA, the bottom is the porous polyethersulfone (Polyethersulfone, PES) support layer, and it is supported by the mechanical support. The catalytic activity of the catalytic layer was observed and the separation characteristics of the composite active catalytic membrane were studied by the removal of butanol water. Finally, the reaction of n-butyl acetate was synthesized by acetic acid / n-butanol as a probe. The reaction and separation of the reaction in the porous catalytic layer CAMR (Catalytically Active Membrane Reactor) under different operating conditions was investigated. By comparing with the traditional IMR (Inert Membrane Reactor) and the dense catalytic layer CAMR, the characteristics and laws of the mass transfer behavior in the membrane reactor are investigated and the characteristics and laws of the mass transfer behavior are studied. The coupling strengthening mechanism of the reactive membrane reactor is analyzed, which proves that the composite catalytic film prepared in this paper can further strengthen the opposite. At last, the transformation rate of the raw material was further improved. Finally, the composite catalytic membrane was developed to the solid catalytic system and the biocatalytic system by the immersion precipitation phase transformation method proposed in this paper. The surface of the porous membrane and the porous catalytic membrane for the preparation of the pure PVA membrane and the porous membrane, the concentration of PVA on the membrane structure When the concentration of PVA is 5wt.%, a colloidal structure is formed and a closed cell cavity or honeycomb like structure is formed when the concentration of PVA is 10wt.%. The increase of the temperature of the coagulation bath is beneficial to the shortening of the film forming time. When preparing the porous catalytic film, the concentration of the catalyst is more suitable for 10wt.% and the concentration of the catalyst is further increased, which tends to form a compact skin. The catalytic activity of different catalysts for the reaction of the probe is: the dense catalytic layer of the granular catalytic layer (PVA concentration 5wt.%) free catalyst cell like catalytic layer (PVA concentration 10wt.%) without catalyst. The pseudo homogeneous phase model is established by the obtained kinetic data, the model prediction results are in good agreement with the experimental values. Well, through the pervaporation and dehydration test of butanol water, the dense catalytic layer CAMR, because the catalytic layer is dense and the thickness of the membrane is large, so the flux is the smallest and the diffusional resistance of the component is the largest. In the porous catalytic layer CAMR, because the catalytic layer is loose porous structure, the flux is larger, it is said that the porous structure is beneficial to reduce the mass transfer resistance of the component. It can only improve the diffusion of the reactant to the catalytic site, and increase the transfer of the product to the back of the membrane, thus improving the in situ removal of water, which is beneficial to the real "in situ" removal. In the reaction separation coupling strengthening experiment, the acetic acid and n-butyl alcohol decrease with time in the IMR, the compact catalytic layer CAMR and the porous catalytic layer CAMR. Small, n-butyl acetate and water rose synchronously at the initial stage, but after a period of time, the change of water concentration was deviated from the concentration curve of n-butyl acetate. As the removal rate of water was greater than that of water, the concentration curve of water in the membrane reactor decreased gradually with time. The increase of temperature could further improve the acetic acid. The change of the total flux also has two stages: at the early stage of the reaction, the flux rises first and reaches the inflection point. At 85, the water concentration in the porous catalytic layer CAMR will be 0 at 28h, and then the water can not be detected in the membrane reactor, but the back flux indicates that the reaction is constantly carried out and the water is constantly removed. It shows that after this time, the product realizes real in situ removal effect, that is, producing a molecular water, spreading to the downstream side of the membrane and removing it. This effect is more obvious with the decrease of the load of the catalyst. When the load of the catalyst is 2.25g/L, the water concentration in the front side in the 23.5h is O.. The catalytic performance and separation performance of the catalytic membrane are adjusted. Through the comparison of IMR and the porous catalytic layer CAMR, it is proved that the composite catalytic film prepared in this paper can further strengthen the process. As the water is generated on the surface of the membrane, the water has a greater driving force and the flux of water is greater, and the conversion rate of acetic acid is higher at the end of the table. At about 35.5 h, IMR The conversion rate of medium acetic acid is only about 75%, but in the porous catalytic layer CAMR, the conversion rate of acetic acid reaches about 85%., and in the contrast of the dense catalytic layer CAMR and the porous catalytic layer CAMR, the rate of water generation and removal is faster and the conversion rate is higher because of the lower mass transfer resistance in the porous catalytic layer. The method of preparation of composite catalytic membrane with porous catalytic layer has a certain versatility of.IER/PVA/PES composite catalytic membrane can also be used to remove the water in situ, achieve the enhancement of conversion rate, and the membrane structure has not changed obviously before and after use, and the Lipase/PVA/PES composite catalytic membrane can maintain the biological activity of the enzyme, and can also be real. Further intensification of the present conversion rate.
【學位授予單位】：北京化工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ032.4;TQ051.893

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