微反应器内沸石与ZIF-8膜的制备及其催化Knoevenagel缩合反应性能研究
发布时间：2018-11-01 14:37
【摘要】：化工过程的微型化是近些年来化工技术领域的一大趋势。作为微化工技术研究的核心,微反应器依靠其强化传质传热、操作安全连续、容易工业放大等优势,在连续催化反应和有机合成等领域获得了广泛的研究。而其中微反应器内催化剂的固定装填问题及构建高效稳定的催化微反应器是关键和难点之一。本文针对不同微反应器的特点,通过不同的组装策略和方法,在微反应器内制备厚度可调的沸石及ZIF-8膜层,构建的膜微反应器应用于催化Knoevenagel缩合反应评价其性能。主要研究内容和结果如下：(1)针对毛细石英管微通道长径比大的特点和常规静态釜内无法制备连续沸石膜层的难点,采用连续流动的合成策略制备了均匀连续的NaX沸石膜层。通过优化合成条件,研究调控膜厚度的规律,结果表明：改变膜合成时间,可方便调控制备不同厚度的沸石膜层。该方法操作简单,为毛细管内制备沸石膜催化层或载体层并构建膜微反应器提供了新思路。NaX沸石膜经Cs+交换形成CsNaX沸石膜催化微反应器,应用于催化苯甲醛与氰基乙酸乙酯的Knoevenagel缩合反应,在优化条件下可获得目标产物接近100%的收率。而且通过在反应体系内引入强吸水性的离子液体IL-BMIC作为水吸收剂,避免反应产生的水对CsNaX催化层的中毒,可使膜催化微反应器稳定运行50 h以上而未见明显失活,解决了沸石催化层的水热失活问题。该过程可实现反应的连续生产,具有潜在的应用开发前景。(2)以毛细石英管作为微通道反应器,针对石英表面惰性、ZIF-8难成核生长成膜的问题,分别采用3-氨丙基三乙氧基硅烷(APTES)辅助和ZnO诱导成核生长两种策略,研究优化流动合成法制备均匀连续的ZIF-8膜。在优化的合成条件下,膜层的厚度可通过膜合成时间来调控,为MOFs膜微反应器的构建提供了新途径。基于疏水性ZIF-8的催化功能,将构建的ZIF-8膜微反应器应用于催化苯甲醛与氰基乙酸乙酯的Knoevenagel缩合反应,在温和的反应条件下可获得目标产物接近100%的收率。与CsNaX沸石膜微反应器相比,ZIF-8膜微反应器表现出温和条件下更高效的催化性能。(3)在多通道片式不锈钢微反应器内,采用常规合成釜内静态法制备了ZIF-8/NaA复合膜。针对不锈钢微通道粗糙的表面形貌和大孔结构,首先采用晶种诱导法制备了均匀连续的NaA沸石层作为中间过渡层,填补载体的大孔使其表面趋于平整；然后通过化学生长制备ZnO层作为功能层诱导制备了连续均匀的ZIF-8膜催化层,ZIF-8沿着NaA沸石膜表面生长形成了ZIF-8/NaA复合膜结构。将此ZIF-8/NaA复合膜微反应器应用于催化苯甲醛与氰基乙酸乙酯的Knoevenagel缩合反应,在温和条件下获得目标产物接近100%的收率,ZIF-8本身的疏水性可防止反应产生的水中毒,催化活性至少保持50 h而未出现明显失活,表现出优良的催化活性和稳定性。该过程为MOFs膜催化微反应器的应用提供了很好的开发前景。(4)在多通道的片式不锈钢微反应器内,基于不锈钢的粗糙表面及导电性,采用物理沉积法和电化学方法沉积ZnO层作为载体修饰和诱导生长双功能层制备了均匀连续的ZIF-8膜层。通过研究沉积不同形态ZnO层、膜合成时间、膜合成液浓度以及活化步骤对制备ZIF-8膜形貌的影响规律,获得了一种在不锈钢微通道内直接制备ZIF-8膜的最佳工艺。将此构建的ZIF-8膜催化微反应器应用于催化苯甲醛与氰基乙酸乙酯的Knoevenagel缩合反应,在温和条件可获得接近100%的目标产物收率,表现出优良的催化活性和稳定性。同ZIF-8/NaA复合膜微反应器相比,该构建方法表现出制备工艺更为简便的优势。
[Abstract]:The miniaturization of chemical process is a trend in the field of chemical engineering in recent years. As the core of the micro-chemical technology research, the micro-reactor relies on its advantages such as strengthening mass transfer heat transfer, safe and continuous operation, easy industrial amplification and the like, and has been widely studied in the fields of continuous catalytic reaction and organic synthesis. The fixed loading problem of the catalyst in the micro-reactor and the construction of efficient and stable catalytic microreactors are one of the key and difficult problems. In view of the characteristics of different micro-reactors, through different assembly strategies and methods, the thickness-adjustable zeolite and ZIF-8 film layer were prepared in the micro-reactor, and the constructed membrane micro-reactor was used to evaluate the performance of the Knoevenagel condensation reaction. The main research contents and results are as follows: (1) According to the characteristics of large aspect ratio of capillary quartz tube microchannel and the difficulty in preparing continuous zeolite membrane layer in conventional static kettle, a uniform continuous NaX zeolite film layer is prepared by continuous flow synthesis strategy. By optimizing the synthesis conditions, the law of controlling the thickness of the membrane is studied. The results show that the formation time of the membrane is changed, and the zeolite membrane layer with different thickness can be conveniently regulated and controlled. The method is simple in operation, and provides a new idea for preparing a zeolite membrane catalytic layer or a carrier layer in a capillary tube and constructing a membrane micro-reactor. CsNaX zeolite membrane catalytic microreactor was formed by CsNaX zeolite membrane via Cs + exchange, which was used to catalyze the Knoevenagel condensation reaction of benzaldehyde with cyanoethyl acetate, and the yield of target product close to 100% could be obtained under optimized conditions. Moreover, by introducing strong water-absorbing ionic liquid IL-BMIC into the reaction system as the water absorbent, the poisoning of the water to the CsNaX catalytic layer caused by the reaction can be avoided, the membrane catalytic microreactor can stably run for more than 50 hours without obvious loss, and the problem of water heat loss of the zeolite catalytic layer is solved. The process can realize continuous production of reaction and has potential application and development prospect. (2) using a capillary quartz tube as a microchannel reactor, aiming at the problem that the quartz surface is inert and ZIF-8 is difficult to nucleate and grow, the three-aminopropyltrimethoxysilane (APTES) auxiliary and the ZnO-induced nucleation and growth strategies are respectively adopted, A uniform continuous ZIF-8 film was prepared by optimized flow synthesis. Under the optimized synthesis conditions, the thickness of the film layer can be regulated by the membrane synthesis time, and a new way is provided for the construction of the MOFs membrane micro-reactor. Based on the catalytic function of hydrophobic ZIF-8, the constructed ZIF-8 film micro-reactor was used to catalyze the Knoevenagel condensation reaction of benzaldehyde and cyanoethyl acetate, and the yield of the target product close to 100% can be obtained under mild reaction conditions. Compared with CsNaX zeolite membrane microreactors, ZIF-8 membrane microreactors exhibit more efficient catalytic performance under mild conditions. (3) ZIF-8/ NaA composite film was prepared by static method in a multi-channel sheet stainless steel microreactor. Aiming at the rough surface morphology and large pore structure of stainless steel micro-channel, the uniform continuous NaA zeolite layer is first prepared as the intermediate transition layer by using crystal seed crystal method, and the large hole of the carrier is filled to make its surface smooth. A continuous uniform ZIF-8 film catalytic layer was prepared by chemical growth of ZnO layer as functional layer, and ZIF-8/ NaA composite film structure was formed along the surface of NaA zeolite membrane. The ZIF-8/ NaA composite membrane micro-reactor is applied to the Knoevenagel condensation reaction of the catalytic benzaldehyde and the cyanide-based ethyl acetate, the yield of the target product close to 100% is obtained under mild conditions, the hydrophobicity of the ZIF-8 itself can prevent water poisoning caused by the reaction, the catalytic activity is maintained for at least 50h without obvious loss, exhibiting excellent catalytic activity and stability. The process provides a good development prospect for the application of the MOFs membrane catalytic microreactor. (4) In a multi-channel plate type stainless steel micro-reactor, a uniform continuous ZIF-8 film layer is prepared by using a physical deposition method and an electrochemical method to deposit a ZnO layer as a carrier modification and inducing growth double functional layer on the basis of the rough surface and the conductivity of the stainless steel. ZIF-8 film was prepared by direct preparation of ZIF-8 film in stainless steel microchannel by studying the influence of deposition on the morphology of ZIF-8 film by deposition of ZnO layer, film synthesis time, film composition concentration and activation step. The ZIF-8 membrane catalytic microreactor constructed here is used to catalyze the Knoevenagel condensation reaction of benzaldehyde and cyanoethyl acetate, and the yield of the target product close to 100% can be obtained under mild conditions, which shows excellent catalytic activity and stability. Compared with the ZIF-8/ NaA composite membrane micro-reactor, the construction method shows the advantages of simpler preparation process.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ052;O621.251
，
本文编号：2304220
[Abstract]:The miniaturization of chemical process is a trend in the field of chemical engineering in recent years. As the core of the micro-chemical technology research, the micro-reactor relies on its advantages such as strengthening mass transfer heat transfer, safe and continuous operation, easy industrial amplification and the like, and has been widely studied in the fields of continuous catalytic reaction and organic synthesis. The fixed loading problem of the catalyst in the micro-reactor and the construction of efficient and stable catalytic microreactors are one of the key and difficult problems. In view of the characteristics of different micro-reactors, through different assembly strategies and methods, the thickness-adjustable zeolite and ZIF-8 film layer were prepared in the micro-reactor, and the constructed membrane micro-reactor was used to evaluate the performance of the Knoevenagel condensation reaction. The main research contents and results are as follows: (1) According to the characteristics of large aspect ratio of capillary quartz tube microchannel and the difficulty in preparing continuous zeolite membrane layer in conventional static kettle, a uniform continuous NaX zeolite film layer is prepared by continuous flow synthesis strategy. By optimizing the synthesis conditions, the law of controlling the thickness of the membrane is studied. The results show that the formation time of the membrane is changed, and the zeolite membrane layer with different thickness can be conveniently regulated and controlled. The method is simple in operation, and provides a new idea for preparing a zeolite membrane catalytic layer or a carrier layer in a capillary tube and constructing a membrane micro-reactor. CsNaX zeolite membrane catalytic microreactor was formed by CsNaX zeolite membrane via Cs + exchange, which was used to catalyze the Knoevenagel condensation reaction of benzaldehyde with cyanoethyl acetate, and the yield of target product close to 100% could be obtained under optimized conditions. Moreover, by introducing strong water-absorbing ionic liquid IL-BMIC into the reaction system as the water absorbent, the poisoning of the water to the CsNaX catalytic layer caused by the reaction can be avoided, the membrane catalytic microreactor can stably run for more than 50 hours without obvious loss, and the problem of water heat loss of the zeolite catalytic layer is solved. The process can realize continuous production of reaction and has potential application and development prospect. (2) using a capillary quartz tube as a microchannel reactor, aiming at the problem that the quartz surface is inert and ZIF-8 is difficult to nucleate and grow, the three-aminopropyltrimethoxysilane (APTES) auxiliary and the ZnO-induced nucleation and growth strategies are respectively adopted, A uniform continuous ZIF-8 film was prepared by optimized flow synthesis. Under the optimized synthesis conditions, the thickness of the film layer can be regulated by the membrane synthesis time, and a new way is provided for the construction of the MOFs membrane micro-reactor. Based on the catalytic function of hydrophobic ZIF-8, the constructed ZIF-8 film micro-reactor was used to catalyze the Knoevenagel condensation reaction of benzaldehyde and cyanoethyl acetate, and the yield of the target product close to 100% can be obtained under mild reaction conditions. Compared with CsNaX zeolite membrane microreactors, ZIF-8 membrane microreactors exhibit more efficient catalytic performance under mild conditions. (3) ZIF-8/ NaA composite film was prepared by static method in a multi-channel sheet stainless steel microreactor. Aiming at the rough surface morphology and large pore structure of stainless steel micro-channel, the uniform continuous NaA zeolite layer is first prepared as the intermediate transition layer by using crystal seed crystal method, and the large hole of the carrier is filled to make its surface smooth. A continuous uniform ZIF-8 film catalytic layer was prepared by chemical growth of ZnO layer as functional layer, and ZIF-8/ NaA composite film structure was formed along the surface of NaA zeolite membrane. The ZIF-8/ NaA composite membrane micro-reactor is applied to the Knoevenagel condensation reaction of the catalytic benzaldehyde and the cyanide-based ethyl acetate, the yield of the target product close to 100% is obtained under mild conditions, the hydrophobicity of the ZIF-8 itself can prevent water poisoning caused by the reaction, the catalytic activity is maintained for at least 50h without obvious loss, exhibiting excellent catalytic activity and stability. The process provides a good development prospect for the application of the MOFs membrane catalytic microreactor. (4) In a multi-channel plate type stainless steel micro-reactor, a uniform continuous ZIF-8 film layer is prepared by using a physical deposition method and an electrochemical method to deposit a ZnO layer as a carrier modification and inducing growth double functional layer on the basis of the rough surface and the conductivity of the stainless steel. ZIF-8 film was prepared by direct preparation of ZIF-8 film in stainless steel microchannel by studying the influence of deposition on the morphology of ZIF-8 film by deposition of ZnO layer, film synthesis time, film composition concentration and activation step. The ZIF-8 membrane catalytic microreactor constructed here is used to catalyze the Knoevenagel condensation reaction of benzaldehyde and cyanoethyl acetate, and the yield of the target product close to 100% can be obtained under mild conditions, which shows excellent catalytic activity and stability. Compared with the ZIF-8/ NaA composite membrane micro-reactor, the construction method shows the advantages of simpler preparation process.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ052;O621.251
，
本文编号：2304220
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