阅读说明：本技术 利用微气泡强化传质的具有多孔泡沫结构的三相微反应器 (Three-phase micro-reactor with porous foam structure and using micro-bubbles to strengthen mass transfer ) 是由 廖强 陈刚 陈蓉 朱恂 叶丁丁 李俊 付乾 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种利用微气泡强化传质的具有多孔泡沫结构的三相微反应器,包括按从上往下顺序设置的上盖板、流道板和下底板；其特征在于：所述流道板中部设置有长方形凹槽,该长方形凹槽的底部为镂空结构,该长方形凹槽的四周向上凸起,形成台阶,该台阶上水平放置陶瓷膜；多孔泡沫板放置于陶瓷膜上,多孔泡沫板上负载有催化剂；多孔泡沫板的顶部与流道板的顶部位于同一水平面；所述下底板与陶瓷膜之间形成空腔,该空腔作为气体流动空间；下底板中部设置有进气孔,进气孔位于陶瓷膜下方；在流道板上位于长方形凹槽的两侧分别设置有树形流道一、二,作为液相反应物的进入和出口通道；本发明可广泛适用于化工、环保等领域。(The invention discloses a three-phase microreactor with a porous foam structure and capable of strengthening mass transfer by utilizing micro bubbles, which comprises an upper cover plate, a runner plate and a lower bottom plate which are arranged from top to bottom in sequence; the method is characterized in that: the middle part of the runner plate is provided with a rectangular groove, the bottom of the rectangular groove is of a hollow structure, the periphery of the rectangular groove is upwards protruded to form a step, and a ceramic membrane is horizontally placed on the step; the porous foam plate is placed on the ceramic membrane, and a catalyst is loaded on the porous foam plate; the top of the porous foam plate and the top of the runner plate are positioned on the same horizontal plane; a cavity is formed between the lower bottom plate and the ceramic membrane and is used as a gas flowing space; the middle part of the lower bottom plate is provided with an air inlet which is positioned below the ceramic membrane; tree-shaped flow channels I and II are respectively arranged on the two sides of the rectangular groove on the flow channel plate and are used as inlet and outlet channels of liquid-phase reactants; the invention can be widely applied to the fields of chemical industry, environmental protection and the like.)

1. A three-phase micro-reactor with a porous foam structure and using micro-bubbles to strengthen mass transfer comprises an upper cover plate (2), a runner plate (5) and a lower bottom plate (6) which are arranged in sequence from top to bottom;

the method is characterized in that: a rectangular groove is formed in the middle of the runner plate (5), the bottom of the rectangular groove (5c) is of a hollow structure, the periphery of the rectangular groove is upwards protruded to form a step (5d), and a ceramic membrane is horizontally placed on the step; the porous foam plate is placed on the ceramic membrane, and a catalyst is loaded on the porous foam plate; the top of the porous foam plate and the top of the runner plate are positioned on the same horizontal plane; a cavity is formed between the lower bottom plate (6) and the ceramic membrane and is used as a gas flowing space; the middle part of the lower bottom plate (6) is provided with an air inlet (6a), and the air inlet (6a) is positioned below the ceramic membrane (4); tree-shaped flow channels I and II (5a and 5b) are respectively arranged on the two sides of the rectangular groove on the flow channel plate (5) and are used as inlet and outlet channels of liquid-phase reactants;

the liquid phase reactant reaches one end of the porous foam plate from the tree-shaped flow channel I (5a), is uniformly distributed in the foam material (3), and flows out of the reactor from the other end of the porous foam plate (3) through the tree-shaped flow channel II (5 b);

gas-phase reactants are introduced from the air inlet holes (6a) of the lower bottom plate, are gathered in the cavity formed between the lower bottom plate (6) and the ceramic membrane, and then form uniformly dispersed micro-bubbles through the ceramic membrane (4) under the action of pressure difference, and the micro-bubbles enter the porous foam plate (3) to perform catalytic reaction with the liquid-phase reactants at the active sites of the catalyst.

2. The three-phase microreactor with a porous foam structure for mass transfer enhancement by microbubbles of claim 1, wherein: the upper cover plate is provided with an observation window, and the transparent glass (1) is embedded in the observation window and used for observing the reaction area.

3. The three-phase microreactor with a porous foam structure for mass transfer enhancement by microbubbles of claim 1, wherein: the microreactor further comprises an injection pump (7), and the injection pump (7) is used for controlling the flow of the liquid-phase reactants.

4. The three-phase microreactor with a porous foam structure for mass transfer enhancement by microbubbles of claim 1, wherein: the microreactor further comprises a gas mass flow controller (8), the gas mass flow controller (8) being adapted to control the flow of the gas-phase reactants.

Technical Field

The invention relates to the field of microreactors, in particular to a three-phase microreactor with a porous foam structure and capable of strengthening mass transfer by using micro-bubbles.

Background

In the heterogeneous catalysis field, a catalyst carrier plays a key role, for example, (1) an active phase is dispersed, and the density of reaction active sites is improved; (2) increasing the stability of active Nanoparticles (NPs) by providing strong metal-support interactions, thereby reducing catalyst deactivation problems due to sintering; (3) promoting the adsorption of reactants to active sites and the rapid desorption of intermediate products; (4) the formation of local hot spots is reduced in the exothermic reaction, thereby avoiding the reduction of the selectivity of the target product and improving the safety of the operation.

So far, in the field of heterogeneous catalysis, new catalyst supports have rarely been introduced, and supports developed several decades ago, such as alumina, silica, titania and activated carbon, have been used in the catalytic process. The carrier can optimize the porosity, mechanical strength and surface acidity by changing the synthesis process, and can also optimize by doping to improve the activity of the catalyst. In the 21 st century, the chemical process is developing in a direction of greenness, high efficiency and safety, and under such a background, the micro-reactor attracts wide attention and research of scholars due to the advantages of large specific surface area, good heat and mass transfer performance, safe operation and the like. The catalyst is still an indispensable component in the microreactor, but the preparation of the above-mentioned catalysts such as alumina and silica usually requires a calcination process (>400 deg.c), which puts high demands on the choice of materials for making the microchannel, and also increases the processing cost of the microchannel. The researchers have proposed the concept of micro-packed bed, i.e. catalyst-loaded nano-microspheres are packed in micro-channels, and good results are obtainedBut has the disadvantage of a large pressure drop in the reactor. The porous foam structure is considered as an ideal substitute carrier, and has the characteristics of interconnected pore structures, high porosity and large specific surface area. The scholars will load Pd/Al₂O₃The foam metal of the catalyst is filled in square micro-channels of 2mm, and the mass transfer rate of the reactor is found to be improved by 50% compared with a control group (non-filled micro-channels), which fully proves the feasibility of the porous foam plate as a catalyst carrier in a microreactor. However, when gas-liquid two phases are used as reactants and enter the porous foam structure, gas can form gas channels in the porous material, meanwhile, the number of the gas channels is greatly influenced by the pore diameter of the porous material, fewer gas channels can directly influence the contact area of the gas-liquid two-phase reactants, at the moment, the gas overcomes the resistance of a liquid film and reaches the active sites of the catalyst to react, the micro-reactor performance is seriously influenced by the larger transmission resistance, and meanwhile, part of the catalyst cannot be utilized, so that the use efficiency of the catalyst is reduced.

The micro bubbles are bubbles with bubbles ranging from hundreds of nanometers to 10 micrometers, the bubbles ranging from small to nanometer to micron have an ultra-large specific surface area, and the specific surface area of the bubbles of 10 micrometers is theoretically 100 times that of the bubbles of 1 millimeter under a certain volume. Meanwhile, the gas-liquid mass transfer efficiency is in inverse proportion to the straight path of the bubbles, and theoretically, the specific surface area of the bubble interface is infinitely increased along with the infinite reduction of the straight path of the bubbles, and finally the internal gas pressure is increased to be infinite due to the self-pressurization effect. The self-pressurization characteristic of the micro bubbles in the contraction and collapse process can continuously enhance the mass transfer efficiency of the gas-liquid interface.

Disclosure of Invention

The invention aims to provide a three-phase microreactor with a porous foam structure, which utilizes micro-bubbles to strengthen mass transfer.

In order to solve the technical problems, the technical scheme of the invention is as follows: a three-phase micro-reactor with a porous foam structure and using micro-bubbles to strengthen mass transfer comprises an upper cover plate, a runner plate and a lower bottom plate which are arranged in sequence from top to bottom;

the method is characterized in that: the middle part of the runner plate is provided with a rectangular groove, the bottom of the rectangular groove is of a hollow structure, the periphery of the rectangular groove is upwards protruded to form a step, and a ceramic membrane is horizontally placed on the step; the porous foam plate is placed on the ceramic membrane, and a catalyst is loaded on the porous foam plate; the top of the porous foam plate and the top of the runner plate are positioned on the same horizontal plane; a cavity is formed between the lower bottom plate and the ceramic membrane and is used as a gas flowing space; the middle part of the lower bottom plate is provided with an air inlet which is positioned below the ceramic membrane; tree-shaped flow channels I and II are respectively arranged on the two sides of the rectangular groove on the flow channel plate and are used as inlet and outlet channels of liquid-phase reactants;

liquid phase reactants reach one end of the porous foam plate from the first tree-shaped flow channel, are uniformly distributed in the foam material, and flow out of the reactor from the other end of the porous foam plate through the tree-shaped flow channel;

gas-phase reactants are introduced from the air inlet of the lower bottom plate, are gathered in the cavity formed between the lower bottom plate and the ceramic membrane, then pass through the ceramic membrane under the action of pressure difference to form uniformly dispersed micro-bubbles, and the micro-bubbles enter the porous foam plate and perform catalytic reaction with the liquid-phase reactants at the active sites of the catalyst.

The invention utilizes the porous foam board as the catalyst carrier, provides larger surface area, thereby improving the loading area and the dispersion degree of the catalyst. In addition, a large amount of uniformly dispersed microbubbles with ultra-large specific surface area are manufactured by utilizing the ceramic membrane, so that the contact area of gas-liquid two-phase reactants is increased, and mass transfer can be effectively enhanced, thereby improving the performance of the microreactor.

According to the preferable scheme of the three-phase microreactor with the porous foam structure and the micro-bubble enhanced mass transfer, the upper cover plate is provided with an observation window, and the transparent glass 1 is embedded in the observation window and used for observing the reaction region.

According to a preferred embodiment of the three-phase microreactor with a porous foam structure for mass transfer enhancement by microbubbles according to the present invention, the microreactor further comprises an injection pump for controlling the flow rate of a liquid-phase reactant.

According to a preferred embodiment of the three-phase microreactor with a porous foam structure for mass transfer enhancement by microbubbles according to the present invention, the microreactor further comprises a gas mass flow controller for controlling the flow of a gas-phase reactant.

The three-phase microreactor with the porous foam structure and the micro-bubble enhanced mass transfer has the advantages that:

1) the invention adopts the porous foam board as the catalyst carrier, is beneficial to improving the loading area and the dispersion degree of the catalyst, is easy to replace the integral catalyst after inactivation, and reduces the cost of the reactor.

2) The tree-shaped flow channel arrangement can enable the distribution of liquid phase reactants to be more uniform.

3) The interconnected pore structure of the porous foam boards is beneficial to the uniform dispersion of the fluid.

4) A large amount of micro bubbles which are uniformly dispersed and have an ultra-large specific surface area are generated by utilizing the ceramic membrane, so that the contact area of gas-liquid reactants can be effectively increased, and the mass transfer is enhanced.

5) The formation of micro-bubbles can be controlled by regulating the pore size distribution of the ceramic membrane, so that different chemical reactions can be regulated.

The invention can be widely applied to the fields of chemical industry, environmental protection and the like.

Drawings

Fig. 1 is a schematic structural diagram of a three-phase microreactor with a porous foam structure and utilizing micro-bubbles to enhance mass transfer according to the invention.

Fig. 2 is a plan view of the flow field plate according to the present invention.

In the drawings: 1-transparent glass; 2, an upper cover plate; 3-porous foam board; 4-ceramic membranes; 5-a runner plate; 5 a-a tree-shaped flow channel I; 5b, a tree-shaped flow channel II; 5c, forming a rectangular groove; 5 d-step; 6-lower bottom plate; 6 a-air inlet; 7-injection pump; 8-gas mass flow controller.

Detailed Description

The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.

Referring to fig. 1 and 2, a three-phase microreactor with a porous foam structure for enhancing mass transfer by using microbubbles comprises an upper cover plate 2, a porous foam plate 3, a ceramic membrane 4, a flow channel plate 5, a lower bottom plate 6, an injection pump 7 and a gas mass flow controller 8; the upper cover plate 2, the runner plate 5 and the lower bottom plate 6 are arranged from top to bottom in sequence;

a rectangular groove is formed in the middle of the runner plate 5, the bottom of the rectangular groove 5c is hollow, the periphery of the rectangular groove 5c is protruded upwards to form a step 5d, and the ceramic membrane 4 is horizontally placed on the step 5 d; the porous foam plate 3 is placed on the ceramic membrane, and a catalyst is loaded on the porous foam plate 3; the top of the porous foam plate 3 and the top of the runner plate 5 are positioned on the same horizontal plane; a cavity is formed between the lower bottom plate 6 and the ceramic membrane 4 and is used as a gas flowing space; the middle part of the lower bottom plate 6 is provided with an air inlet 6a, and the air inlet 6a is positioned below the ceramic membrane 4; the gas inlet hole 6a is connected with a gas mass flow controller 8, and the gas mass flow controller 8 is used for controlling the flow of the gas-phase reactant. Tree-shaped flow channels I, II, 5a and 5b are respectively arranged on the two sides of the rectangular groove on the flow channel plate 5 and are used as inlet and outlet channels of liquid-phase reactants;

the injection pump 7 is used for controlling the flow rate of the liquid phase reactant. The liquid phase reactant reaches one end of the porous foam plate from the first tree-shaped flow channel 5a, is uniformly distributed in the foam material 3, and flows out of the reactor from the other end of the porous foam plate 3 through the second tree-shaped flow channel 5 b;

gas-phase reactants are introduced from the air inlet holes 6a of the lower bottom plate, are gathered in a cavity formed between the lower bottom plate 6 and the ceramic membrane, then pass through the ceramic membrane 4 under the action of pressure difference to form uniformly dispersed micro-bubbles, and the micro-bubbles enter the porous foam plate 3 to perform catalytic reaction with the liquid-phase reactants at the active sites of the catalyst.

The upper cover plate is provided with an observation window, and the transparent glass 1 is embedded in the observation window and used for observing the reaction area.

Under the thrust of the injection pump 7, a liquid-phase reactant reaches one end of the porous foam plate 3 from an inlet through the first tree-shaped flow channel, is uniformly distributed in the porous foam plate 3, and flows out of the reactor from the other end of the porous foam plate 3 through the first tree-shaped flow channel; the gas-phase reactant is subjected to flow control through a mass flow controller 8, is introduced from a lower bottom plate air inlet 6a, is gathered in the cavity, then forms uniformly dispersed microbubbles with ultra-large specific surface area through a ceramic membrane 4 under the action of pressure difference, and the microbubbles enter the porous foam plate 3 to perform catalytic reaction with the liquid-phase reactant at active sites; then the gas-liquid two-phase reactant and the product flow out of the reaction area from the tree-shaped flow passage.

When the method is used specifically, a nitrobenzene solution is injected into the microreactor by using an injection pump 7, the nitrobenzene solution enters a reaction area from the first tree-shaped flow channel 5a and is uniformly dispersed under the action of the porous foam plate 3, a gas-phase reactant hydrogen enters a cavity formed between the lower base plate 6 and the ceramic membrane from an air inlet 6a under the control of a gas mass flow controller 8, the gas is continuously accumulated along with the increase of time, the gas passes through the ceramic membrane 4 under the action of pressure to form a large number of uniformly dispersed micro bubbles, the hydrogen bubbles enter the porous foam plate and are subjected to catalytic reaction with the nitrobenzene solution at catalyst active sites, and a gas-liquid two-phase reactant and a liquid-phase product flow out of the reactor from the second tree-shaped flow channel 5 b.

Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art may still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some technical features. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.