JP2005169213A - Microreactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microreactor which easily forms a very small reaction space (microspace) and makes the resident time and flow of a reaction fluid constant as much as possible. <P>SOLUTION: A plurality of flat plates 2 provided with inlets and outlets for a reaction fluid are laminated, and a gasket 4 is arranged between the plates so that a microspaces 20 of 10-1,500 μm in height (H) may be formed, and at least one microspace formed between the two flat plates has a ratio of a flow channel width (W) to the height (H) of 20-10,000. The microreactor is applicable, for example, to a synthesis of hydrogen from methanol by arranging a catalyst element comprising a methanol-converting catalyst in a front stage microspace as a reaction part and arranging a hydrogen separation membrane in a latter stage microspace as a separation part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a microreactor, that is, a reaction apparatus in which a minute reaction space is formed.

JP-T-2001-524019 "Microreactors", WILEY-VCH, p30, 2000 "Development of a general-purpose microreactor by element assembly", C316, Proceedings of the 67th Chemical Engineering Society Annual Meeting

  There is known a microchemical device in which a concave portion is formed on a base material such as silicon, glass, metal, plastic, etc. by various methods such as cutting, etching, molding, and this is used as a fluid path or a gel channel for separation (for example, Non-Patent Document 1). Further, in Patent Document 1, in a microreactor including at least one planar fluid path and a fluid inlet and outlet, a metal side wall in which the fluid path is arranged opposite to each other, and another extending between the side walls. A microreactor has been proposed which is partitioned by metal or plastic side walls and closed by brazing or gluing, with closing means sealing the fluid paths open to each other and / or the planes. However, the conventional microreactor has a small ratio W / H between the flow path height H and the flow path width W in order to increase the ratio between the space volume and the internal surface area. In order to make it large, there are many cases where a plurality of flow paths are provided on one surface or the flow path length is long and curved. For this reason, the shape of the laminated thin plates is complicated, requires advanced techniques and long processes for processing, and is disadvantageous in terms of cost.

  Non-Patent Document 2 describes a microreactor in which a large number of thin cylindrical microspaces are stacked, but the shape of the inlet and outlet of the reaction fluid into the microspace is a pore, and the flow of the reaction fluid is There was a problem in that it was not constant and a long residence time or a short residence time was mixed.

  An object of the present invention is to provide a microreactor in which a minute reaction space (microspace) can be easily formed and the residence time and flow of the reaction fluid can be made as constant as possible.

  The inventors of the present invention have made extensive studies to achieve the above object, and in a structure in which a gasket is sandwiched between flat plates, a micro space is easily formed by giving a specific ratio to the channel width and channel height. This completes the present invention.

  That is, according to the present invention, a plurality of flat plates each having a reaction fluid inlet / outlet are stacked, and a gasket is arranged between the flat plates so that a micro space with a height (H) of 10 to 1500 μm is formed. At least one microspace formed between the flat plates is a microreactor characterized in that the ratio of channel width (W) / height (H) is 20 to 10,000.

  Further, according to the present invention, at least one micro space has a thin rectangular parallelepiped shape having a height (H), a width (W) corresponding to the channel width (W), and a length (L). Is provided with a slit-like inlet of the reaction fluid on one flat plate and a slit-like outlet of the reaction fluid on the other flat plate on the downstream side of the reaction fluid, and the long side width (Y) of the slit-like inlet or outlet The ratio of the short side width (X) is 4 to 100, and the long side width (Y) is 80% or more of the width (W).

  Further, according to the present invention, a catalyst element having a thickness (T) of 1/10 to 9/10 of a height (H) is mounted in at least one micro space. A microreactor as described above.

In the present invention, two or more pairs of flat plates and gaskets are alternately stacked, so that a plurality of microspaces having a flow path width (W) / height (H) ratio of 20 to 10,000 are arranged in series. The microreactor as described above.
Furthermore, in the present invention, when two or more pairs of flat plates and gaskets are alternately laminated, by using gaskets having different thicknesses, microspaces having different flow path width (W) / height (H) ratios are connected in series. A microreactor as described above.

Further, the present invention is the above-described microreactor that performs reaction, separation, or both by inserting a catalyst element, separation means, or both into a microspace.
Furthermore, the present invention is the above-described microreactor that performs reaction, separation, or both by loading different catalyst elements, separation means, or both into a plurality of microspaces.

In the present invention, the reaction space width (R) represented by the difference between the thickness (T) of the catalyst element charged in the micro space and the height (H) of the catalyst is 50 to 500 μm. It is a reactor.
Furthermore, the present invention is the above microreactor in which the thickness (T) of the catalyst element is 20 to 300 μm.
The present invention is also the above microreactor in which the catalyst element is a metal catalyst-supporting carbon membrane.

Furthermore, the present invention provides a reforming reaction section by placing a methanol conversion catalyst as a catalyst element in a reaction section comprising a micro space charged with the catalyst element, and a separation section by placing a hydrogen separation membrane in the separation means. This is a method for synthesizing hydrogen.
Here, the reaction temperature is 180 to 380 ° C., or the flow width of one micro space constituting the reforming reaction section is 20 mm or more, and the residence time in this micro space is within 2 seconds. Is preferred.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the basic structure of the microreactor of the present invention, FIG. 2 is a plan view of a flat plate that is arranged in an intermediate stage of the microreactor and forms a micro space, and FIG. It is sectional drawing when a catalyst element and a separation membrane are arrange | positioned at the microreactor of this invention.

  In FIG. 1, the microreactor forms a plurality of micro spaces 20 by a flat plate 1 at the bottom, a plurality of flat plates 2 and an upper flat plate 3 arranged in the middle, and a plurality of gaskets 4 arranged between the flat plates. ing. The reaction fluid inlet 5 is connected to the hole 7 of the bottom flat plate 1 and the outlet 6 is connected to the hole 9 of the upper flat plate 3. In addition, the plurality of flat plates 2 arranged in the intermediate portion are provided with slits 8 that serve both as an inlet and an outlet, and the reaction fluid charged from the inlet 5 sequentially passes through the plurality of microspaces 20, and finally It is discharged from the outlet 6. Here, in order to integrate these flat plates into a microreactor, holes for passing bolts 10 are provided at the four corners outside the position where the gasket 4 is arranged, and are tightened by bolts 10 and nuts 11. And the airtightness of the micro space 20 is maintained.

  In FIG. 1, there are a plurality of micro spaces 20, but one or more micro spaces 20 may be used, and the range is preferably 3 to 50. At least the number of gaskets 4 required to form the required number of microspaces is the same, and the total number of flat plates is one more than that.

  As shown in FIG. 1, the height H of the micro space 20 can be controlled by the thickness of the gasket 4, and the width can be controlled by the size of the flat plate and the position where the gasket 4 is disposed. An arbitrary flat plate 22 arranged in the middle portion constitutes one micro space 24 with the flat plate 21 arranged adjacent to the upstream side, and at the same time, one flat plate 23 arranged adjacent to the downstream side. A space 25 is formed. Therefore, the slit 8 provided in the arbitrary flat plate 22 is not only an outlet from the upstream microspace 24 but also an inlet of the microspace 25.

In FIG. 2, a rectangular ring-shaped gasket 4 is arranged around an arbitrary flat plate 22 arranged in the intermediate portion, and the interior surrounded by the gasket forms a micro space. In addition, a slit 8 is provided at one end of the inner flat plate 22 surrounded by the gasket, from which the reaction fluid from the upstream micro space 24 flows, and the micro space 25 formed between the flat plates 22 and 23 is formed. It flows to the other end side and flows out from the slit 8 ′ provided in the flat plate 23 represented by the dotted line to the micro space 26 on the downstream side. Here, the flow path width W in FIG. 2 refers to the width W, and the flow path length refers to the length X. In FIG. 2, dotted lines provided at the four corners of the flat plate 22 indicate the positions of the bolt 10 and the nut 11.
In the drawings, the flat plate and the gasket are illustrated as rectangular, but they may be slightly deformed. However, a rectangular or almost rectangular shape is preferable.

The microspace in the present invention has a height H of 10 to 1500 μm, and a channel width W is a value satisfying the relationship of W / H = 20 to 10,000, and is in the range of 200 μm to 15 m, preferably The height H is 0.1 to 1.0 mm, the flow path width W is in the range of 10 to 200 mm, and W / H = 100 to 2000. The channel length X is preferably in the range of 0.5 to 2.0 times the channel width W, and is preferably in the range of 10 to 200 mm.
The reaction fluid passing through the micro space preferably forms a laminar flow at a uniform speed in the flow path in the space. When the thickness of the gasket, that is, the height H exceeds 1500 μm, distribution in the height direction is likely to occur, and the same tendency exists even when W / H is less than 20.

  As the flat plate, a rectangular or substantially rectangular plate is preferably used. The gasket is preferably similar in shape to a flat plate and is slightly smaller. The micro space is determined by the size of the flat plate and the size of the gasket. The height H of the space is determined by the thickness of the gasket, the flow path width W is determined by the lateral width W of the gasket, and the flow path length X is substantially determined by the width L in the length direction of the gasket. The maximum size of the gasket is determined by the size of the flat plate, but the minimum size of the gasket is arbitrarily determined.

  The slit 8 serving as the inlet and outlet of the reaction fluid to the micro space is provided on the flat plate in the space surrounded by the gasket, but provided on the end side in the length direction, the inlet slit 8 and the flat plate on the downstream side thereof. The exit slits 8 are provided in parallel or substantially in parallel. Here, the length direction refers to the direction in which the reaction fluid flows, the width direction refers to the flow path width direction, the flow path width W coincides with the width of the gasket, and the flow path length X is the slit at the inlet. And the width to the exit slit provided in the flat plate on the downstream side. The slit may be rectangular or almost rectangular, but the long side A and the short side B may have an A / B ratio of 4 to 100, preferably 10 to 50. The long side A is desirably a value close to the flow path width W, and is preferably 80% or more in order to make the flow of the reaction fluid constant. Similarly, the flow path length X is preferably 80% or more of the width L in the length direction of the gasket in order to effectively use the micro space.

  The microreactor of the present invention has at least one microspace, but the range of 3 to 50 is preferable as described above. Moreover, it can also have the space which remove | deviates from micro space said by this invention if needed. Furthermore, the plurality of microspaces may have different heights H and flow path widths W, whereby the residence time in each microspace can be adjusted.

  The shape of the plurality of flat plates may be any shape depending on the purpose, but is preferably large enough to stably fix the gasket. By making the shape of the flat plate much larger than the outer periphery of the gasket, the heat transfer area for the reaction volume is expanded, and the function of a fin-type heat exchanger for removing the heat necessary for the reaction and removing the generated heat is provided. Is also possible. The gasket may have an arbitrary shape, but in order to maintain a laminar flow at a uniform speed in the flow path, the inner periphery thereof is preferably rectangular. It is more preferable that the slits provided in the flat plate are also arranged at positions along opposite sides of the gasket inner circumference.

  The material of the flat plate and the gasket can be arbitrarily selected depending on the conditions to be used. Examples of the material to be used include metals such as stainless steel, glass, quartz, ceramics, plastics such as fluororesin and PEEK, and metals are preferable from the viewpoint of smoothness, workability, and low cost. The gasket may be made of a material such as metal as long as it provides airtightness, but rubber or the like is not suitable for high temperature reaction. In addition to slits and bolt holes, irregularities for fixing the catalyst may be provided if necessary on the flat plate surface of the portion constituting the micro space, but it is convenient not to provide grooves or the like. .

  As shown in Fig. 1, two or more pairs of flat plates 2 and gaskets 4 are alternately stacked, and a plurality of microspaces 20 are arranged in series, so that a long reaction time is required, etc. And it can be increased easily. In order to increase the reaction volume by increasing the flat plate area, there is a limit in maintaining the sealing property between the flat plate and the gasket. The present invention is suitable for the structure shown in FIG. 1 because the apparatus can be made compact because the partition walls of the two microspaces can be shared by a single flat plate. Moreover, it is advantageous also in the easiness of member processing, and economical efficiency.

  Moreover, the height H of the micro 20 can be arbitrarily adjusted by changing the thickness of the gasket 4 according to the purpose of use. A reaction space suitable for changes in reaction type, conditions, and reactant flow rate can be easily formed. In particular, in a stacked type apparatus, it is possible to set different reaction volumes, residence times, and linear velocities by using gaskets having different thicknesses for specific stages in a plurality of reaction spaces. It is advantageous for promoting, delaying, closing, etc.

  Furthermore, as shown in FIG. 3, a catalyst element 27 is mounted or filled in the microspace 20 to provide a solid catalytic reaction microreactor. The catalyst element 27 can be selected in any shape such as a thin plate shape, a fiber shape, and a granular shape that can be accommodated in the micro space. It is better to insert the element. Since the catalyst element is often deteriorated and needs to be replaced, it is preferable that the catalyst element has a shape integrated in a plate shape, a honeycomb shape, or the like so that the replacement is easy. In order to make the space width in the height direction (reaction space width R) formed by the catalyst element and the flat plate as uniform as possible and achieve a stable laminar flow in the reaction space, a thin plate shape is preferable. Various types of catalyst elements can be selected depending on the purpose of use, and different catalyst types can be loaded for each stage. The thickness T of the catalyst element is in the range of 20 to 300 μm, preferably in the range of 50 to 250 μm. The ratio of the thickness T of the catalyst element to the height H of the micro space is in the range of 0.1 to 0.9, preferably in the range of 0.2 to 0.8.

  Separation means can be provided in the micro space together with the catalyst element or separately from the catalyst element. If a separation means is provided together with the catalyst element, the reaction and the reaction product can be separated and purified. Examples of the separation means include adsorption (including chromatographic separation and the like), ion exchange, and filtration (including treatment with a separation membrane and the like). Examples of materials used for such purposes include activated carbon, silica gel, zeolite, ion exchange resin, gas separation membrane, and various filters. It is also possible to perform a plurality of reactions (for example, a decomposition reaction and an oxidation reaction, two types of hydrogenation reactions, etc.) and separation and purification by arranging a plurality of reaction catalysts and separation means in the same reactor.

  The method of assembling the microreactor of the present invention is not only the method of fixing with bolts 10 and nuts 11 as shown in FIG. 1, but also the method of sandwiching both ends with clamps, and the method of incorporating the required number of units into a certain size housing It can take various forms. In either case, it is possible to easily assemble and disassemble the device.When using it for multiple purposes, it is very easy to reposition and replace each stage, adjust the position during use, disassemble and clean, etc. Yes. Furthermore, when an integrated catalyst element is used, operability that is extremely effective for attaching a catalyst, removing an unnecessary catalyst, exchanging a catalyst, and the like is exhibited.

  Examples of the use of the microreactor of the present invention include adsorption removal of a specific organic component using an activated carbon membrane, decomposition reaction of a volatile organic compound (VOC component), and hydrogen production by methanol reforming. Especially, the hydrogen production apparatus for fuel cells is the most preferable use example. In recent years, various devices for producing hydrogen by reforming reactions using hydrocarbons such as methanol as raw materials have been developed and proposed by vigorous research and development of fuel cells. Therefore, it is understood that the reaction fluid referred to in the present invention is not limited to those that cause a chemical reaction, but includes those that contain an adsorption component, a filtration component, and the like.

  The microreactor of the present invention is particularly excellent as an on-site small reactor intended for use in automobiles or small electronic devices. In the steam reforming reaction of methanol using a copper-based catalyst and the decomposition reaction using a nickel-based catalyst, the reformed gas contains several percent of CO as a by-product in addition to H2 and CO2, so the anode of the fuel cell stack As a result, poisoning of the platinum-based catalyst used in the battery will greatly reduce battery output. For this reason, in order to reduce the CO concentration as much as possible, many of them have an oxidation part that performs selective oxidation of CO after cooling to a temperature suitable for the reaction. However, this apparatus has a carbon film or an inorganic film in the same reactor. A separation / purification unit loaded with a hydrogen separation membrane can be provided, and hydrogen with a very low CO concentration can be produced and recovered with one apparatus.

  An application example will be described with reference to FIG. 3 as a reactor for methanol reforming reaction. A source gas composed of methanol gas and water vapor as a reaction fluid passes through the inlet 5 and is introduced into the first microspace 20 from the hole 7 of the bottom plate 1. In this space, a catalyst element 27 carrying a methanol reforming catalyst is loaded, and the raw material gas component reacts while contacting the catalyst element, and passes through the hole 8 at the end of the flow path provided in the flat plate 2 thereon. It moves through to the second micro space (reaction space) and reacts in contact with the catalytic element. This movement is sequentially performed to complete the desired reaction. At least one micro space (separation space) in which the hydrogen separation membrane 28 is installed is provided on the downstream side of the micro space where the reaction is completed, and separation and purification are performed by flowing a reaction product gas therethrough.

  As the catalyst element for the methanol reforming reaction, a carbon film or a silica film carrying a metal such as copper, zinc, iron, nickel, palladium or the like can be used, and a carbon film is preferable. This carbon film can be prepared relatively easily by firing a metal-containing organic thin film, etc., and a film having a desired thickness can be prepared by controlling the casting conditions and firing conditions of the organic thin film. Suitable for Advantageously, it is a catalyst obtained by dispersing a metal catalyst or metal compound catalyst in a polyimide or polyimide precursor solution, forming it into a film, drying and carbonizing.

  The reaction temperature for methanol reforming is 180 to 380 ° C, preferably 230 to 280 ° C. When the reaction temperature is lower than 180 ° C., a sufficient conversion rate cannot be obtained. When the reaction temperature is higher than 380 ° C., the decomposition reaction proceeds and the amount of hydrogen recovered decreases. In order to maintain the reaction temperature, the entire reactor may be heated in an oven or the like, or the flat plate in each stage may be directly heated with a heater. The residence time in the reforming reaction section is preferably within 20 seconds. If the residence time exceeds 20 seconds even at a reaction temperature of 180 ° C., the decomposition rate of the product increases, and the hydrogen selectivity rapidly decreases.

It is preferable to provide a space above the catalyst element 27, and the height of this space is 50 to 500 μm, preferably 100 to 200 μm. If this is larger than 500 μm, the contact between the raw material gas and the catalyst element is not sufficient, and the conversion rate of methanol decreases. On the other hand, if it is smaller than 50 μm, the resorption or decomposition reaction of the reaction product on the catalyst surface proceeds, and the hydrogen selectivity is greatly reduced.
Further, the flow path width of one micro space in which the catalyst elements are arranged is preferably 50 mm or more, and the residence time in contact with all the catalyst elements is preferably 20 seconds or less.

  Finally, the reaction unit enters the separation / recovery unit, passes through the hydrogen separation membrane 28 or further the adsorbent layer, separates hydrogen, adsorbs CO, and collects high-purity hydrogen. Known hydrogen separation membranes and adsorbents can be used.

  In the microreactor of the present invention, an arbitrary micro space can be easily formed by simply laminating plates and gaskets alternately, and the manufacturing cost has been greatly reduced. By changing the thickness of the gasket according to the purpose of use, the height of the reaction space can be arbitrarily adjusted, and a reaction space suitable for changes in reaction types, conditions, and reaction fluid flow rates can be easily formed. In addition, in a stacked apparatus, it is possible to set different reaction volumes, residence times, and linear velocities by using gaskets with different thicknesses for specific stages in a plurality of reaction spaces. It is advantageous for promoting, delaying, closing, etc. The microreactor of the present invention is particularly excellent as an on-site small reactor intended for use in automobiles and small electronic devices. In addition, this device can be equipped with a separation / purification unit such as a carbon membrane or an inorganic membrane hydrogen separation membrane in the same reactor. It can be recovered.

A methanol reformer having the following configuration was manufactured in the shape shown in FIGS.
As the metal flat plate, a flat plate made of SUS304, 50 mm × 50 mm, thickness 500 μm was used, and a 1 mm × 32 mm slit was cut at a position along the inner side of the gasket. Three types of gaskets made of SUS304, having a square ring shape with an outer side of 34 mm × 34 mm and a width of 2 mm, having a thickness of 200 μm, 500 μm, and 1000 μm were used.
A 32 mm x 32 mm, 150 μm thick carbon membrane carrying metal and nickel is used as the catalyst element (metal loading is about 20 wt%, average 0.05 g / sheet), and a microporous carbon membrane is used as the hydrogen separation membrane. It was.
The methanol reformer has 9 stages of methanol reforming sections, 2 cases of 21 stages, and 2 stages of separation and purification sections. The entire reformer was installed in an oven equipped with a temperature controller, and a reforming reaction was performed at 180 to 380 ° C. The gas flow rate was adjusted so that the average residence time per stage was 0.84 seconds.
The results are shown in Table 1. The hydrogen yield is mol / mol based on the methanol used.

Two types of gaskets, SUS304, 34 mm x 34 mm, width 2 mm, with a thickness of 500 μm and 1500 μm, are used as catalyst elements, and a 32 mm × 32 mm, 150 μm thick carbon film carrying nickel (about the amount of metal supported) 20 wt%, average 0.05 g / sheet) was used, and the configuration was the same as in the previous example.
The reformer has 9 stages of methanol reforming sections, 2 cases of 25 stages, and 2 stages of separation and purification sections. The reaction was carried out at 150 to 450 ° C. by placing the entire reactor in an oven equipped with a temperature controller. The gas flow rate was adjusted so that the average residence time per stage was 0.84 seconds.
The results are shown in Table 2. The hydrogen yield is mol / mol based on the methanol used.

Sectional view showing an example of basic structure of microreactor Plan view of the flat plate placed in the middle stage of the microreactor Cross-sectional view of the microreactor catalyst element and separation membrane

Explanation of symbols

1 Bottom plate
2 flat plate
3 Upper plate
4 Gasket
5 Reaction fluid inlet
6 Exit
7, 8, 9 holes
10 volts
11 Nut
20 micro space

Claims (13)

  A plurality of flat plates each having a reaction fluid inlet / outlet are stacked, and a gasket is arranged between the two flat plates so that a micro space with a height (H) of 10 to 1500 μm is formed between the flat plates. At least one microspace has a ratio of channel width (W) / height (H) of 20 to 10,000.   At least one microspace has a thin rectangular parallelepiped shape with a height (H), a width (W) corresponding to the flow path width (W), and a length (L), and one flat plate constituting this one microspace The reaction fluid is provided with a slit-like inlet of the reaction fluid, the other flat plate on the downstream side of the reaction fluid is provided with a slit-like outlet of the reaction fluid, and the long side (A) / short side (B) of the slit-like inlet or outlet The microreactor according to claim 1, wherein the ratio is 4 to 100, and the long side width (A) is 80% or more of the width (W).   2. A catalyst element having a thickness (T) of 1/10 to 9/10 of a height (H) is mounted in at least one micro space. Or the microreactor of 2.   A plurality of microspaces having a flow path width (W) / height (H) ratio of 20 to 10,000 are arranged in series by alternately laminating two or more sets of flat plates and gaskets. 4. The microreactor according to any one of 3.   5. When two or more sets of flat plates and gaskets are alternately laminated, by using gaskets having different thicknesses, microspaces having different channel widths (W) / heights (H) are arranged in series. The microreactor as described.   The microreactor according to any one of claims 1 to 5, wherein the reaction, separation, or both are performed by inserting a catalyst element, separation means, or both into the microspace.   The microreactor according to claim 6, wherein the reaction, separation, or both are performed by inserting different catalyst elements, separation means, or both into a plurality of microspaces.   The microreactor according to claim 6 or 7, wherein a reaction space width (R) represented by a difference between a thickness (T) of the catalyst element charged in the microspace and a height (H) of the space is 50 to 500 µm. .   The microreactor according to any one of claims 6 to 8, wherein the catalyst element has a thickness (T) of 20 to 300 µm.   The microreactor according to any one of claims 6 to 9, wherein the catalyst element is a metal catalyst-supported carbon membrane.   A reaction part charged with the catalyst element of the microreactor according to any one of claims 6 to 10 is used as a reforming reaction part using a methanol conversion catalyst as a catalyst element, and a hydrogen separation membrane is used as a separation means. A method for synthesizing hydrogen, characterized by comprising a separation unit.   The method for synthesizing hydrogen according to claim 11, wherein the reaction temperature is 180 to 380 ° C.   The method for synthesizing hydrogen according to claim 11 or 12, wherein the flow path width of one micro space constituting the reforming reaction section is 50 mm or more and the residence time is 20 seconds or less.

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