JP4500787B2 - Microreactor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a novel microreactor and a method for producing the same. Specifically, a microreactor having an effective catalytic activity while having a high reactant flow rate by supporting a catalytic metal on cylindrical porous silica having characteristic hollow through-holes and nanopores, and a method for producing the same Is to provide.

  Microreactors that are used in microsynthetic processes such as separation and synthesis of substances have conventionally formed minute channels on the order of microns on substrates of chemically resistant polymers such as metals, glass, and silicon, The inner wall of the flow path is configured by performing necessary surface chemical modification or immobilization of an active substance. For example, in the case of a minute synthesis related to a catalytic reaction, a glass substrate is often formed by engraving a concave portion that becomes a minute flow path and attaching another glass substrate to this.

  However, the microreactor has room for improvement such as homogeneous loading of the catalyst layer, flow path design, processing complexity, and increased pressure loss.

  On the other hand, there are two through-holes that are continuous in a three-dimensional network made of macropores having a pore diameter of about 0.1 to 100 μm and nanopores having a pore diameter of several nanometers to several tens of nanometers. A rod-shaped dual pore fused silica capillary column in which primary pore silica is formed has been proposed (see, for example, Patent Document 1).

  This capillary column with built-in rod-shaped binary pore silica has a binary pore structure with two types of pores, continuous pores and nanopores, in a three-dimensional network consisting of macropores. It is. And the use as a column for a gas chromatograph, a liquid chromatograph, or a solid phase extraction is shown using such a complicated macropore structure and the nanopore structure which continues to this.

  However, the above-mentioned document does not disclose any use of the present invention as a microreactor in which a catalytic metal is supported on a capillary column, and the three-dimensional network-like macropores are not disclosed. When the above-mentioned capillary column is used as a microreactor, it has high pressure loss due to a complicated macropore structure, it is difficult to achieve a high reactant flow rate, and it is possible to achieve high efficiency and high activation of the reaction. It is difficult to obtain a microreactor.

JP-A-11-287791

  Therefore, an object of the present invention is to form a flow path as a reaction zone very easily as compared with a conventional microreactor, to obtain a high flow rate of a reactant, and to provide a high-performance microreactor having an effective catalytic activity. To provide a reactor.

  As a result of intensive studies to solve the above problems, the present inventors have filled a sol solution composed of a silicon source, a water-soluble polymer and an acid catalyst into a capillary with a fine diameter of 10 to 1000 μm. The sol solution is phase-separated into a specific state and then gelled to obtain silica having nanopores in the capillary with a hollow through hole in the center of the capillary. Succeeded. In addition, such a special structure of silica (cylindrical porous silica) can achieve a high reactant flow rate, and the catalyst metal is formed on the inner wall of the cylindrical porous silica in which nanopores exist. As a result, it was found that effective catalytic activity is exhibited in the flow path, and the present invention has been completed.

That is, in the present invention, a capillary having an inner diameter of 10 to 1000 μm is filled with a sol solution containing a silicon source, a water-soluble polymer and an acid catalyst, and then the sol solution is reduced to a concentration in which the concentration of the silicon source is reduced in the center of the capillary. After the phase separation so as to be formed, the gelation is completed, and the gel is dried and fired, and is made of porous silica having nanopores and having a diameter of 0.1 to 100 μm. A microreactor characterized in that a catalytic metal is supported on at least the inner wall surface of the hollow through-hole of cylindrical porous silica having a hollow through-hole.

  In the present invention, the cylindrical porous silica is preferably formed in a capillary.

Further, in the present invention, the microreactor is produced by filling a capillary having an inner diameter of 10 to 1000 μm with a sol solution containing a silicon source, a water-soluble polymer and an acid catalyst, and then placing the sol solution in the center of the capillary. After phase separation is performed so that a phase having a reduced concentration of the silicon source is formed, gelation is completed , the gel is dried and fired to obtain cylindrical porous silica, and then the cylindrical porous silica A method of impregnating a catalyst metal compound solution into
And a capillary having an inner diameter of 10 to 1000 μm filled with a sol solution containing a catalytic metal-containing silicon source, a water-soluble polymer and an acid catalyst, and then the phase of the sol solution in the center of the capillary with a reduced concentration of the silicon source. Further , the present invention also provides a production method in which gelation is completed after the phases are separated so as to form, and the gel is dried and fired .

  According to the microreactor of the present invention, a catalyst metal is supported on cylindrical porous silica having a structure having a characteristic hollow through-hole and a nanopore continuous therewith, so that a high reaction is achieved in the hollow through-hole. A material flow rate can be achieved, and a high-performance microreactor can be constructed by supporting a catalyst on the inner wall of the hollow through hole.

  In the design of the microreactor process, the reactor can be configured very easily compared to the conventional method of forming the flow path with a glass plate, and effective contact with the catalyst layer can be achieved by controlling the capillary length. The time can be designed freely, and the reaction temperature can be easily controlled because of the capillary shape.

  Furthermore, since the microreactor of the present invention is a cylindrical body, by connecting a plurality of microreactors carrying different catalytic metals in series, a plurality of functions such as sequential reaction and separation should be expressed continuously. Microreactor integration and process configuration are possible.

  Furthermore, the reaction amount can be adjusted by arranging a plurality of microreactors carrying the same kind of catalytic metal in parallel.

  Therefore, it can be said that the present invention is extremely useful in applications requiring a microreactor such as a portable fuel cell and a combinatorial chemistry reactor.

  The microreactor of the present invention is composed of porous silica having nanopores, and the greatest feature is that cylindrical porous silica having hollow through-holes with a diameter of 0.1 to 100 μm is used as a catalyst metal support. Have.

  The hollow through-hole of the cylindrical porous silica functions as a flow path for a fluid containing a reactant, and a catalyst is supported on nanopores existing on the inner wall of the hollow porous silica, so that a good reaction activity can be obtained. it can.

  In addition, the hollow through hole is characterized in that it is formed with an extremely narrow diameter compared to a hollow capillary column such as a conventional liquid phase hollow capillary column or solid phase hollow capillary column. Good contact with the inner wall where the catalyst is present.

  In the present invention, the diameter of the hollow through hole is in the range of 0.1 to 100 μm, desirably 1 to 50 μm, and more desirably 5 to 50 μm. That is, when the diameter of the hollow through hole is larger than 100 μm, there is a possibility that the catalytic activity may be lowered due to an increase in the short path amount of the raw material in the supplied fluid. On the other hand, when the diameter of the hollow through hole is smaller than 0.1 μm, the pressure loss of the fluid is large, which is not practical.

  In the present invention, the outer diameter of the cylindrical porous silica forming the hollow through hole is not particularly limited. However, in the manufacturing method described later, from the ease of forming the hollow through hole, a diameter of 10 to 1000 μm, particularly It is desirable that it is 25-200 micrometers.

  In the present invention, the diameter of the hollow through hole can be obtained by an electron microscope observation image of a cross section of the cylindrical porous silica or a pressure loss evaluation method described later, as will be described later.

  Further, on the inner wall of the hollow through-hole of the cylindrical porous silica of the present invention, fine nanopores continuous therewith are formed, and these nanopores are made of a substance having a catalytic function (catalytic metal). It is carried and acts as a reaction point or an adsorption point.

  Accordingly, the average diameter of the nanopores is preferably 2 to 15 nm, and particularly preferably 2 to 10 nm, in order to sufficiently exhibit such a function. That is, when the average diameter of the nanopores is 2 nm or less, or exceeds 15 nm, when used as a catalytic reaction microreactor, the adsorption ability of the reactant in the porous silica layer decreases, and the catalytic reaction rate is reduced. It tends to decrease.

  The pore diameter of the nanopore can be measured by a so-called nitrogen adsorption method. Details are as shown in the examples described later.

  In the present invention, the volume of the nanopore is generally 0.2 to 1.5 cc / g, preferably 0.3 to 1.0 cc / g.

  FIG. 1 is a schematic view showing a typical embodiment of a microreactor of the present invention using the above-mentioned cylindrical porous silica.

  If it demonstrates according to a figure, the microreactor of this invention will be comprised by the porous silica 3 which has a nanopore, and a metal catalyst (figure is shown on the inner wall surface of the hollow through-hole of the said cylindrical porous silica 1 which has the hollow through-hole 2 is shown. (Not shown).

  In the present invention, the catalyst metal is supported on at least the inner wall surface of the hollow through hole 2 constituted by the porous silica 3. The amount of the metal catalyst supported varies depending on the catalyst activity, reaction conditions, etc., and is not generally limited, but the minimum amount of metal catalyst that can be obtained by experiment is the lower limit, and the amount that does not block the nanopores is the upper limit. As appropriate. The thickness of the metal catalyst may be only the surface of the inner wall made of porous silica, but it is preferably 10% or more of the thickness of the cylindrical porous silica. Of course, it can be present in the entire layer of cylindrical porous silica.

  In the microreactor of the present invention, a known metal catalyst can be used for the intended reaction without particular limitation. Examples of typical metal catalysts include platinum group elements such as platinum, rhodium and palladium, copper and nickel.

  In the figure, 4 is a capillary. Such capillaries are necessary when producing cylindrical porous silica, which may be removed after production of the cylindrical porous silica. However, in order to maintain the strength at the time of reaction when handling the cylindrical porous silica, it is preferable to handle it as a structure in which the outer surface is covered with a capillary without being removed from the cylindrical porous silica. The specific description of the capillary will be made in the description of the method for producing cylindrical porous silica described later.

  Since the microreactor of the present invention has a hollow through hole formed in a straight tube shape, the resistance is small as compared with the case where a conventional rod-shaped dual pore fused silica capillary is used for such applications, Variations in residence time of reaction chemical species for each lot are extremely small. For example, when a plurality of reaction chemical species are used in parallel, a difference in reaction rate between the microreactors can be reduced.

  In the present invention, the cross-sectional shape of the cylindrical porous silica and the cross-sectional shape of the hollow through-hole are not particularly limited, but the cross-sectional shape of the hollow through-hole is preferably circular, and the cross-sectional shape of the cylindrical porous silica is also It is desirable to make it circular corresponding to this. By making it correspond in this way, a certain thickness can be given to the cylindrical porous silica along the circumferential direction on the cross section, and the reaction can be improved.

  As described above, the shape of the hollow through-hole and the cross section of the cylindrical porous silica can be variously selected depending on the application. For example, a triangle, a square or more polygon, or an ellipse can be selected. is there.

  The length of the cylindrical porous silica is not particularly limited, but is desirably in the range of 1 mm to 50 m. Particularly, when setting in the reactor, 5 mm to 5 m, preferably 0.5 to 4 m. It is desirable to be within the range.

  Furthermore, the thickness of the cylindrical porous silica is not particularly limited. In order to develop a good catalytic reaction rate in the use as a microreactor, it is generally desirable to be within the range of 0.5 to 50 μm, and particularly desirably within the range of 1 to 30 μm.

(Method for producing cylindrical porous silica constituting the microreactor)
Hereinafter, the manufacturing method of the said cylindrical porous silica is demonstrated. Although a manufacturing method is not specifically limited as long as the said cylindrical porous silica can be manufactured, Typically, it can manufacture with the following method.

  In the manufacturing method according to the present embodiment, a capillary having an inner diameter in the range of 10 to 1000 μm is filled with a sol solution containing a silicon source, a water-soluble polymer and an acid catalyst, and then the sol solution is placed in the center of the capillary. It is preferably produced by causing the phase separation so that a phase having a reduced concentration of the silicon source is formed and by allowing gelation to proceed. Here, the “capillary central part” means a central part in the cross section, and in the case of a circular cross section, for example, the vicinity of the center point of the circle is the central part.

  The capillary is preferably a tube having a desired inner diameter as described above and has hydrophilicity on the inner wall, and any known material can be used without particular limitation as long as this condition is satisfied. For example, a fused silica glass tube, a soda glass tube, a resin tube having a hydrophilic inner surface, a metal tube, or the like can be used. By using a resin tube, it is possible to obtain a cylindrical porous silica without a capillary by manufacturing the cylindrical porous silica and then removing the resin tube by thermal decomposition.

  The reason why the inner wall of the capillary is made hydrophilic is that when a sol solution is supplied to the capillary to advance phase separation, a phase with a reduced concentration of the silicon source is formed at the center of the capillary. That is, of the composition of the sol solution, the aqueous phase portion containing a silicon source rich in hydrophilicity is phase-separated on the tube wall side, and the organic phase having a low silicon source concentration is phase-separated on the center portion of the tube, thereby forming a hollow through hole Can be formed.

  Here, a known method can be adopted as a method for imparting hydrophilicity to the inner wall of the capillary. For example, when using fused quartz or soda glass as a material, it is preferable to expose the inner wall to an aqueous alkaline solution to make the surface hydrophilic.

  The method of filling the capillary with the sol solution is not particularly limited, and for example, it is possible to fill the capillary with a small inner diameter by reducing the pressure in the capillary and sucking the sol solution.

  In the production method of the present invention, silicon alkoxides such as methoxysilane and ethoxysilane, and water glass are preferably used as the silicon source in the sol solution. Water glass is a concentrated aqueous solution of alkali silicate, and the kind and concentration thereof are not particularly limited. Sodium silicate JIS No. 3 which is a water glass of JIS standard or equivalent is easy to handle as a silicon source.

  The water-soluble polymer in the sol solution is theoretically an organic polymer that can form a solution having an appropriate concentration and can be uniformly dissolved in a solution containing a silicon source. Is preferred. Specifically, sodium or potassium salt of polystyrene sulfonic acid, which is a polymer metal salt, polyacrylic acid which is a polymer acid and dissociates to become a polyanion, and a polyacrylamine which is a polymer base and generates a polycation. Or polyethyleneimine, neutral polymer, polyethylene oxide having a ter bond in the main chain, polyvinyl alcohol having a hydroxyl group in the side chain, or polyvinylpyrrolidone having a carbonyl group. In particular, polyethylene glycol is more desirable from the viewpoint of handling, and its molecular weight is desirably in the range of 1000 to 100,000, and more desirably in the range of 10,000 to 50,000.

  In the present invention, the water-soluble polymer is added to phase-separate the sol solution, and a surfactant is used as an additive for phase separation instead of the water-soluble polymer. Is also possible. However, in this case, it is preferable to use a polar organic solvent such as alcohol or ketone in order to stably perform the phase separation.

  In the present invention, the acid catalyst in the sol solution serves as a catalyst for the hydrolysis reaction and is added to promote gelation. Usually, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, or organic acids are used. .

In the present invention, the ratio of the silicic acid source, the water-soluble polymer, and the acid catalyst in the sol solution may be any composition that can be phase-separated to form a silica-rich phase and can be gelled. The concentration of the silicic acid source is 10 to 200 g / L, preferably 30 to 150 g / L in terms of SiO ₂ , and the concentration of the water-soluble polymer is 10 to 200 g / L, preferably 20 to 60 g / L. Is appropriate. Further, the final acid concentration is desirably within a range of 0.001 to 5 mol per liter of the final solution, more desirably within a range of 0.1 to 5 mol, and further within a range of 1 to 4 mol. It is.

  As described above, the phase separation in the capillary is performed by phase separation of the water phase portion containing the hydrophilic silicon source on the tube wall side and the organic phase having a low concentration of the silicon source at the center portion of the tube. Then, gelation is allowed to proceed to obtain a wet gel. After the phase separation and gelation are completed in this way, the organic phase can be removed by calcination, and the portion from which the organic phase has been removed becomes a hollow through hole.

  As a typical method for proceeding with the gelation, it is desirable to leave the sol solution after phase separation in the range of 0 to 80 ° C., more preferably in the range of 20 to 70 ° C. for 10 minutes to 1 week, Desirably, it is allowed to stand in the range of 1 to 24 hours within any of the above temperature ranges.

  Since gelation generally proceeds simultaneously during phase separation, when obtaining cylindrical porous silica, experiments are performed in advance, and gelation occurs until the desired hollow through-hole is formed by phase separation. It is preferable to determine the temperature and the standing time so as not to be completed.

  In the above-described method for producing cylindrical porous silica, the diameter of the hollow through-hole can be adjusted mainly by the inner diameter of the capillary used, the concentration of the silicon source in the sol, the time until completion of phase separation, etc. .

  The gel obtained as described above is allowed to dry within a range of several hours to several tens of hours within a range of 30 to 80 ° C. After drying, the mixture is baked to remove organic substances. The range of the baking temperature is preferably 100 to 1100 ° C, more preferably 2000 to 700 ° C. In the case where water glass is used as the silicon source, it is highly desirable to wash the produced wet gel before drying it. This is because when the wet gel from the water glass is dried as it is, the gel collapses as the drying proceeds. Therefore, in this case, it is highly desirable to perform washing to remove alkali metal such as sodium in the wet gel before drying, and remove it as an alkali metal salt.

  It is highly desirable to control the pore diameter of the cylindrical porous silica obtained by the above method by further aging in a basic aqueous solution. The aging is desirably performed at a temperature of 0 to 80 ° C. in an alkaline solution of 0.01 to 10 N, but these aging conditions can be appropriately selected so as to obtain a desired pore diameter.

  In the present invention, the method for obtaining a microreactor by loading a catalyst metal on cylindrical porous silica is not particularly limited, but various known loading methods can be applied. For example, at the time of producing the cylindrical porous silica, a method in which a catalytic metal compound is previously present in the raw silicon source, and an impregnation method in which the cylindrical porous silica is impregnated with a solution in which the catalytic metal compound is dissolved are preferably used.

  Examples of the catalytic metal compound include catalytic metals, for example, platinum group elements such as platinum, rhodium and palladium, and nitrates and chlorides such as copper and nickel.

  Among the methods described above, in the method in which the catalyst metal compound is previously present in the raw silicon source during the production of the cylindrical porous silica, the catalyst metal compound is preferably mixed in an aqueous system together with the silicic acid source. Moreover, the above-mentioned method is similarly applied to other conditions for obtaining cylindrical porous silica.

  On the other hand, in the impregnation method, the impregnation solution is preferably a method in which cylindrical porous silica is impregnated in a solution state in which a catalytic metal compound is dissolved in a solvent. As the solvent, for example, a polar solvent such as water or alcohol is used, and water is particularly preferable.

  Moreover, a carboxylic acid compound can also be added to the solution used for the impregnation method as necessary.

  The carboxylic acid compound is not particularly limited, but citric acid and lactic acid are preferably used. In particular, a catalytic metal catalyst produced using lactic acid exhibits high activity. The reason for this is not clear, but the agglomeration of the catalyst metal is suppressed since there is no agglomeration due to crystallization of the salt of the catalyst metal in the drying step when the catalyst is produced, or there is no rapid reaction of organic matter decomposition during the firing. This is probably due to this.

  The mixing ratio of the catalyst metal compound and the solvent in the solution used for the impregnation method is not particularly limited and can be appropriately determined so as to obtain a desired amount of the catalyst metal supported, but a uniform solution that does not cause precipitation or the like is obtained. is required. When the carboxylic acid compound is added, a homogeneous solution that does not cause precipitation or the like can be obtained, and the catalytic metal compound / carboxylic acid compound amount ratio is in the range of 0.1 to 5 in terms of improving the catalytic activity. Is preferred.

  In order to support the catalyst metal on the cylindrical porous silica by the impregnation method, the above-mentioned solution may be impregnated in the dual pore silica. However, in order to increase the supporting efficiency, degassing can also be performed. . Moreover, impregnation and drying can be repeated a plurality of times using a solution having a low catalyst metal concentration.

  Since the cylindrical porous silica after impregnation contains a compound, a solvent and the like in the pores, the solvent may be volatilized and the organic substance may be decomposed by heat treatment.

Such heat treatment is usually in the range of 300 to 1,000 ° C., preferably in the range of 500 to 800 ° C. that does not reduce the specific surface area of silica. The atmosphere during the heat treatment is preferably in oxygen gas or air in order to promote organic matter decomposition. By the heat treatment, the catalytic metal compound is oxidized to obtain catalytic metal oxide / SiO ₂ .

In the method for producing a microreactor of the present invention, in order to obtain a catalyst metal, the catalyst metal oxide / SiO ₂ is heat-treated under a hydrogen stream to reduce the catalyst metal oxide to a catalyst metal. The hydrogen flow rate and heat treatment temperature in the heat treatment under the hydrogen stream are not particularly limited, and are appropriately determined in consideration of the amount of the catalyst metal oxide / SiO ₂ treatment.

  FIG. 2 shows an example of a simple reaction apparatus incorporating the microreactor of the present invention. In FIG. 2, a microreactor 5 in which a catalytic metal is supported on cylindrical porous silica is heated by a heater 8 as needed, and one or more kinds of reaction raw materials 7 are supplied from a line. The reaction raw material is reacted in the hollow through-hole of the microreactor and then returned to the tank 6 by a line. A part of the reaction raw material is taken out as a product 9 and purified as necessary.

  Hereinafter, the present invention will be described more specifically with reference to examples.

(Measurement of copper loading)
The amount of copper supported on the cylindrical porous silica was measured as CuO content by energy dispersive X-ray fluorescence analysis (Shimadzu EDX-900HS).

(Pressure loss evaluation)
For the evaluation of pressure loss of the cylindrical porous silica, the cylindrical porous silica in which the hollow through-holes were formed was cut into a length of 20 mm without removing it from the capillary. The pressure difference before and after passing through the hollow through hole caused by flowing compressed air through the hollow through hole was measured with a differential pressure gauge, and the flow rate of the compressed air after passing through the hollow through hole was measured with a flow meter.

  The measured flow rate and the pressure loss per unit length were plotted, and the diameter of the hollow through-hole of the cylindrical porous silica was determined by the Hargen-Poiseille calculation formula.

Hargen-Poiseillele equation: ΔP / L = 32 μu / D ²
(Μ: viscosity of air = 1.81 × 10 ⁻⁵ ), u: flow velocity, D: diameter of hollow through hole u = Q / (π (D / 2) ² ), so ΔP / L = (128 μ / ΠD ⁴ ) · Q, the slope obtained from the plot of flow rate and pressure loss per unit length is the braces in this formula, and D = (128μ / π (slope)) ^1/4 to hollow through hole Is obtained.

(Measurement of pore size distribution)
The pore size distribution was calculated from the desorption isotherm of nitrogen at the liquid nitrogen temperature (-195.78 ° C.) obtained by ASAP2000 using the Dollimore-Heal method. Moreover, the average pore diameter was calculated | required as an average value of the said distribution.

  The amount of the sample used was about 0.02 g, which was used after vacuum drying at 300 ° C. for 1 hour before measurement. The specific surface area was calculated from the adsorption isotherm using the BET method, and the pore volume was determined from the amount of nitrogen adsorbed when 0.95 <P / Po <1.0.

(Catalyst activity evaluation)
In order to investigate the catalyst performance of the microreactor according to this embodiment, FID gas chromatography (manufactured by Shimadzu Corporation, GC-14B) was used to measure the conversion rate to propane in the following reaction.

C ₃ H ₆ + H ₂ → C ₃ H ₈
* FID gas chromatography (manufactured by Shimadzu Corporation, GC-14B)
-Separation column Ceram. Soc. Japan, 113 (2005) 634-636. 1 was used, and the length was 2 m, which is a length capable of separating propane and propylene.

・ Carrier gas H ₂ (20 kPa)
-Separation column temperature Room temperature The analysis results of gas chromatography were monitored by a personal computer, and the peak area and the half-value width were determined using dedicated software (Graph Analyzer). In FID gas chromatography, the peak area was measured by a dedicated integrator (C-R6A Chromatopac manufactured by Shimadzu Corporation).
Conversion to propane (%) = (Propylene consumed) / (Propylene supplied) × 100
Example 1
A commercially available fused silica capillary (0.100 mm (inner diameter) × 0.200 mm (outer diameter), 1 m (length), manufactured by GL Sciences)) was used to change the SiO ₂ on the inner surface of the capillary to Si—OH. 1N NaOH aqueous solution was put into a fused silica capillary and aged at 50 ° C. for 1 day.

  Thereafter, the inside was washed with water. 12 g of water and 1.22 g of concentrated nitric acid were added, and then 1.0 g of polyethylene glycol (hereinafter referred to as PEG) having an average molecular weight of 20000 was added and dissolved while stirring. Further, 0.48 g of copper nitrate trihydrate (the amount of copper added was 5.2% by weight as CuO) was dissolved in the aqueous solution. Thereafter, 10 g of tetraethoxysilane (hereinafter referred to as TEOS) was added, and the mixture was covered and stirred at room temperature for about 10 minutes until uniform.

  The obtained transparent sol was sucked with an aspirator for 15 minutes to remove bubbles. The sol from which bubbles were removed was introduced into a fused silica capillary by an aspirator. Both ends of the fused silica capillary were sealed with silicon stoppers, and the plastic case was sealed with vinyl tape, and allowed to stand at a temperature of 50 ° C. for 24 hours for gelation.

  The obtained wet gel was dried at 50 ° C. for 1 week while remaining in the capillary. After the drying, baking was performed at 300 ° C. for 1 hour.

  It was confirmed with an electron microscope that porous silica was uniformly present at a thickness of about 26 μm on the inner wall of the fused silica capillary obtained by the above method and constituted cylindrical silica.

  The diameter of the hollow through-hole obtained by the pressure loss evaluation of the microreactor made of cylindrical porous silica thus obtained was 50 μm.

The pressure loss value of the obtained microreactor at an air flow rate of 5 × 10 ⁻² cm ³ / s is 5 MPa / m, and the pressure of a conventional particle-filled capillary or a capillary filled with dual-pore silica is used. The pressure loss is lower than the loss value level of 20 MPa / m.
Further, the nanopores of the porous silica were measured by a nitrogen adsorption method, and had a specific surface area of 695 m ² / g and a pore volume of 0.40 cm ³ / g. From this, the average pore diameter was 2.3 nm. I confirmed that there was. FIG. 3 shows a cross section of the cylindrical porous silica of the microreactor prepared in this example.
Moreover, as a result of measuring the amount of copper supported on the cylindrical porous silica of the obtained microreactor by fluorescent X-ray analysis, it was 6.0% by weight as CuO. Similarly, when the amount of added copper nitrate trihydrate is 0.96 g (copper addition amount is 9.9% by weight as CuO), the amount of supported copper is 10.1% by weight and the amount of added copper nitrate trihydrate is 1.55 g ( When the amount of copper added is 15.0% by weight as CuO), the amount of copper supported is 15.0% by weight, the amount of added copper nitrate trihydrate is 2.19g (the amount of copper added is 19.9% by weight as CuO) The amount of copper supported was 19.9% by weight.

  Moreover, it was confirmed by the observation of an element distribution display electron microscope that the copper element which comprises a catalyst exists over the whole layer of cylindrical porous silica. Thus, it can be seen that copper is almost uniformly introduced into the silica gel layer on the inner wall of the capillary.

The prepared four types of microreactors were reduced in advance with hydrogen at a hydrogen flow rate of 30 cm ³ / min at a temperature of 300 ° C. for 1 hour, and then the microreactor was connected to a silica gel separation column with an adapter, using hydrogen as a carrier, Using FID-GC, the reaction temperature was changed from 50 ° C. to 300 ° C., and the conversion rate to propane by hydrogenation of propylene was measured.

In the above reaction, chromatograms at main temperatures at a copper loading of 10.1% are shown in FIGS. FIG. 10 shows the reaction temperature dependence of the conversion rate determined from the chromatogram measurement results at each copper loading. In any case of copper loading, the conversion rate increases as the reaction temperature increases. If the copper loading amount is 15% by weight or more, the conversion rate becomes 100% at a reaction temperature of 150 to 200 ° C. These results confirmed the high catalytic activity of the microreactor.
Example 2
The same capillary as in Example 1 was subjected to the same pretreatment, and then the inside of the capillary was washed with water. On the other hand, 12 g of water and 1.22 g of concentrated nitric acid were put in a container, and then 1.0 g of PEG having an average molecular weight of 20000 was added and dissolved while stirring. Thereafter, 10 g of TEOS was added, and the mixture was covered and stirred for about 10 minutes at room temperature until uniform.

  The obtained transparent sol was sucked with an aspirator for 15 minutes to remove bubbles. The sol from which bubbles were removed was introduced into a fused silica capillary by an aspirator. Both ends of the fused silica capillary were sealed with silicon stoppers, the plastic case was sealed with vinyl tape, and allowed to stand at 50 ° C. for 24 hours for gelation.

  The obtained wet gel was dried at 50 ° C. for 1 week. Capillaries used in the microreactor were baked at 300 ° C. for 8 hours after drying. It was confirmed with an electron microscope that a silica gel layer was uniformly present at a thickness of about 24 μm on the inner wall of the fused silica capillary and constituted cylindrical silica.

  The diameter of the hollow through-hole obtained by the pressure loss evaluation of the microreactor made of cylindrical porous silica thus obtained was 50 μm.

The nanopores of the porous silica, as measured by the nitrogen adsorption method, have a specific surface area of 703 m ² / g and a pore volume of 0.40 cm ³ / g. From this, the average pore diameter is 2.2 nm. It was confirmed.

A pre-prepared impregnation solution consisting of 1.75 g of copper nitrate trihydrate, 22.68 g of water, and 0.65 g of lactic acid in an equimolar amount with copper nitrate trihydrate was sucked with an aspirator for 15 minutes to remove bubbles. . The impregnation solution from which bubbles were removed was introduced into the fused silica capillary by an aspirator. This impregnation operation was performed three times, and then calcined at 300 ° C. for 1 hour. Thereafter, a hydrogen reduction treatment was performed for 1 hour at a hydrogen flow rate of 30 cm ³ / min and a temperature of 300 ° C. to produce a microreactor.

  As a result of measuring the amount of copper supported on the cylindrical porous silica of the obtained microreactor by fluorescent X-ray analysis, it was 20.3% by weight as CuO (the amount of copper added was 19.8% by weight as CuO).

  As a result of measuring the conversion rate to propane by hydrogenation of propylene at a reaction temperature of 200 ° C. using FID-GC, the microreactor was connected to a silica gel separation column with an adapter, and the conversion rate was 100%.

Comparative Example 1
In Example 2, the conversion rate to propane by hydrogenation of propylene was measured in the same manner except that no catalyst metal was supported. As a result, the conversion rate was 0%.

Schematic of the microreactor according to the present invention Schematic diagram of process using microreactor Electron micrograph showing copper distribution in the microreactor cross section Chromatogram of propylene hydrogenation reaction at a temperature of 60 ° C. with a copper loading of 10.1%. Chromatogram of propylene hydrogenation at 80 ° C with 10.1% copper loading. Chromatogram of propylene hydrogenation reaction at a temperature of 100 ° C. with a copper loading of 10.1%. Chromatogram of propylene hydrogenation reaction at a temperature of 150 ° C. with a copper loading of 10.1%. Chromatogram of propylene hydrogenation reaction at a temperature of 200 ° C. with a copper loading of 10.1%. Chromatogram of propylene hydrogenation reaction at a temperature of 300 ° C. with a copper loading of 10.1%. Reaction temperature dependence of conversion to propane for each copper loading

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical porous silica 2 Hollow through-hole 3 Porous silica 4 Capillary 5 Microreactor 6 Tank 7 Reaction raw material 8 Heater 9 Product

Claims (4)

After filling a sol solution containing a silicon source, a water-soluble polymer and an acid catalyst into a capillary having an inner diameter of 10 to 1000 μm, a phase in which the concentration of the silicon source is reduced is formed in the center of the capillary. Cylinder having hollow through-holes with a diameter of 0.1 to 100 μm made of porous silica having nanopores, obtained by completing gelation, drying and baking the gel after phase separation A catalytic reactor is supported on at least the inner wall surface of the hollow through-hole of the porous silica.   The microreactor according to claim 1, wherein the inner wall of the capillary has hydrophilicity. After filling a sol solution containing a silicon source, a water-soluble polymer and an acid catalyst into a capillary having an inner diameter of 10 to 1000 μm, a phase in which the concentration of the silicon source is reduced is formed in the center of the capillary. After the phase separation, gelation is completed , the gel is dried and calcined to obtain cylindrical porous silica, and then the cylindrical porous silica is impregnated with a catalytic metal compound solution. Item 3. A method for producing a microreactor according to Item 1 or 2. After a capillary having an inner diameter of 10 to 1000 μm is filled with a sol solution containing a catalyst metal-containing silicon source, a water-soluble polymer and an acid catalyst, the sol solution has a phase in which the concentration of the silicon source is reduced at the center of the capillary. after allowed phase separation so as to form, to complete the gelation, drying the gel, the manufacturing method according to claim 1 or 2, wherein the microreactor is characterized that you fired.

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