JP2012192383A - Method for producing compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method for further improving productivity in a gas-liquid reaction process using a minute space.SOLUTION: There is provided a method for producing a compound by reacting a reactant with a reaction gas in a flow channel with an equivalent diameter of 1 μm to 5 mm. In the method, the reaction gas is introduced into the flow channel from at least two places, and a ratio of a length of a reaction gas segment to the equivalent diameter of the flow channel in a reaction field is 0.75 or more. Here, preferably, the reactant is an alcohol and the product is a compound including a carbonyl group, and preferably, the reaction gas contains oxygen of at least 10 vol% or more.

Description

  The present invention relates to a method for producing a compound in which a reaction gas is introduced in multiple stages.

  In recent years, a process using a minute space has attracted attention as a technique for improving heat selectivity and mixing efficiency with higher efficiency and improving reaction selectivity and process energy efficiency than conventional macro devices. Such a method using a micro space is often classified as a microprocess, but the scale is not limited to the micro order, and this classification is often applied when the features of the micro space are successfully used. More specifically, a process that uses a space of about millimeter to submicron and uses a phenomenon peculiar to the minute space is called a microprocess.

  When the reaction is carried out using this process, there is an advantage that by making the apparatus small, mass transfer due to diffusion is accelerated, which favors the reaction and leads to reduction of waste and cleaning solvent. It is also easy to scale up, and the results achieved using a single reaction channel at the lab scale can be affected in the reaction field if the production volume is increased by the numbering up that incorporates the integration technology and system control system. It is possible to scale up without receiving any.

  However, on the other hand, the pressure loss increases due to the small size of the device, and a high-pressure compatible pump may be required, so that the micro flow path is not necessarily advantageous compared to a macro production device.

  For example, Patent Document 1 describes a method of performing a gas-liquid reaction by filling a reaction field having an inner diameter of 1 μm to 1 mm with a fine particle catalyst as a reaction operation utilizing the characteristics of a minute space.

  Patent Document 2 describes a method of performing a catalytic oxidation reaction between an organic compound and ozone in a microreactor.

  Patent Document 3 describes a method of introducing a reaction gas a plurality of times in a gas-liquid reaction using a minute space.

JP 2007-209973 A JP 2004-285001 A JP 2007-105668 A

  According to the methods described in the above prior art documents, it is possible to perform a gas-liquid reaction using the characteristics of the microchannel, but each has the following problems.

  In the method described in Patent Document 1, the solid catalyst is filled in the flow path, and the reaction field length becomes long in order to secure a residence time for obtaining a necessary reaction rate. Although the method described in Patent Document 2 can use the entire minute space as a reaction field, the reaction field length is long as in Patent Document 1 because all reaction gases necessary for obtaining a desired reaction rate are initially introduced. Become. In the method described in Patent Document 3, it is proposed to introduce the reaction gas a plurality of times, but it is specified as a preferable range that the reaction gas is additionally introduced after the reaction gas is consumed by 50% or more. However, depending on the amount of reaction gas introduced at the initial stage, if the flow state changes before consumption by 50%, it is more likely that productivity will be further improved by promptly conducting additional introduction.

  In view of the above, it has been desired to develop an operation method that further improves productivity in a gas-liquid reaction using a minute space.

  The present invention is a method for producing a compound by reacting a reaction substrate and a reaction gas in a flow path having an equivalent diameter of 1 μm to 5 mm, and introducing the reaction gas into the flow path from two or more locations in the reaction field. In this method, the ratio between the equivalent diameter of the flow path and the segment length of the reaction gas is 0.75 or more.

  According to the present invention, the length of a reaction apparatus for obtaining a necessary alcohol reaction rate can be shortened, and the apparatus cost can be reduced. In other words, it is possible to increase the productivity of the product when the apparatus length is the same.

It is a figure which shows an example of embodiment of this invention. It is a figure which shows the example different from embodiment of this invention.

  In the method for producing a compound of the present invention, when a reaction substrate and a reaction gas are reacted in a flow path having an equivalent diameter of 1 μm to 5 mm, the reaction gas is introduced into the flow path from two or more locations, and the flow path in the reaction field The ratio of the segment length of the reaction gas to the equivalent diameter is 0.75 times or more.

  The equivalent diameter in the present invention is defined as the diameter of a circle having the same area as the cross section perpendicular to the flow direction of the flow path.

  The segment length of the reaction gas is an average of the lengths in the flow direction of the reaction gas existing in the reaction tube, and when visible, it can be confirmed by obtaining an average length of 20 points or more by photography. If visual inspection is not possible, the reaction gas segment length can be obtained by calculation if the stoichiometric equation of the reaction, the conversion rate of the reaction substrate, and the order of solubility of the reaction gas in the solvent are known. . When a material that cannot be visually observed is used and the order of solubility of the reaction gas in the solvent is not clear, a corresponding visualization experiment can be performed to predict the segment length. Corresponding visualization experiments can be performed by thinning the thickness and visualizing by replacing only a part of the channel wall surface with a transparent material such as glass.

  In this reaction, a reactor having a flow path with an equivalent diameter of 1 μm to 5 mm is used. The reactor is a reactor having an equivalent diameter of 1 μm or more, preferably 10 μm or more, more preferably 100 μm or more, and a flow path of 5 mm or less, preferably 4 mm or less, more preferably 2 mm or less. It may consist of a plurality of tubes, or may be a combination of a plurality of tubes. When the equivalent diameter is less than 1 μm, problems such as a reduction in throughput, an increase in pressure loss, and an increased risk of clogging occur. When the equivalent diameter exceeds 5 mm, the mass transfer rate due to a decrease in the gas-liquid interface area decreases. The reduction reduces the advantages of the microprocess.

  The cross-sectional shape of the flow path can be circular, elliptical, semicircular, triangular, quadrangular or other polygonal shapes, and the shape may change in the middle of the flow path. In this case, the equivalent diameter may change. When the equivalent diameter changes, it is necessary to set the flow rate conditions of the reaction gas and the reaction liquid so that the ratio of the segment length of the reaction gas to the equivalent diameter is 0.75 or more.

  The method of setting the ratio of the reaction gas segment length to the equivalent diameter of the flow path to 0.75 or more is not particularly limited, but is usually at least 0.1 times the volume flow rate of the reaction liquid at the reaction temperature. It is preferable to distribute the reaction gas at a volume flow ratio.

  The length of the flow path is not particularly limited as long as it is a residence time necessary to obtain a desired reaction rate, but the shorter the length, the apparatus cost can be reduced. It is desirable to set

  The material constituting the flow path is not particularly limited as long as it does not inhibit the reaction, but is preferably a material excellent in heat resistance to the reaction temperature and corrosion resistance to the reaction solution, and specifically represented by SUS316 or the like. Stainless steel, alloys such as Inconel 600, glass such as quartz, and organic polymers such as PTFE and ETFE can be used.

  Examples of the method for producing the compound of the present invention include a production method utilizing a reaction such as a gas-liquid alcohol oxidation reaction, a gas-liquid solid alcohol oxidation reaction, a gas-liquid alcohol hydrogenation reaction, a gas-liquid solid alcohol hydrogenation reaction, etc. Can be mentioned. Among them, the gas-liquid alcohol oxidation reaction is preferable from the viewpoint of many reactions that can be operated at a relatively low reaction pressure and avoiding an irregular flow mode due to the presence of a solid catalyst.

  The gas-liquid alcohol oxidation reaction is not particularly limited. For example, among the reactions well known as the gas-liquid alcohol oxidation reaction, a reaction that requires mass transfer between the reaction gas and the liquid can be mentioned. Among them, a gas containing oxygen is used as an oxidizing reaction gas, and is effective for a gas-liquid oxidation reaction in which an oxide is dissolved in a solution.

  At this time, the concentration of oxygen contained in the reaction gas is preferably as high as possible because the dissolved concentration becomes higher as the partial pressure is higher than Henry's law. Usually, 5 volume% or more is preferable and 10 volume% or more is more preferable. 100% by volume is most preferred.

  The reaction gas may contain a gas other than oxygen as long as the reaction is not inhibited. Specifically, ozone, hydrogen, fluorine, chlorine, carbon monoxide, carbon dioxide, sulfur dioxide, hydrogen chloride, ammonia, nitrogen And nitric oxides. One or more of these gases may be mixed with the reaction gas.

  Examples of the reaction substrate include aliphatic primary alcohols, secondary alcohols, tertiary alcohols, and aromatic alcohols. Since the reaction is an oxidative dehydrogenation type reaction, aliphatic primary and second alcohols are used. Grade alcohols are preferred. Examples of the alcohol include aliphatic primary alcohols typified by 1-hexanol and 1-butanol, aliphatic secondary alcohols typified by isopropanol and 2-butanol, and compounds having an acyloin skeleton typified by acetoin and lactic acid. Etc.

  The solvent for the reaction solution containing a reaction substrate such as alcohol is not particularly limited as long as it does not inhibit the reaction. Usually, water, organic solvents, ionic liquids, etc., which are general-purpose reaction solvents, can be used. I can do it. Specifically, organic solvents include aliphatic hydrocarbons typified by hexane and octane, aromatic hydrocarbons typified by benzene and toluene, compounds having a carbonyl group typified by acetone and diethyl ketone, and typified by acetonitrile. Nitriles, methanol, alcohols typified by ethanol, amines typified by triethylamine, interoxane compounds typified by dioxane, pyridine, etc., and a mixed solvent of any ratio of these two or more types Can also be used.

  When a solvent is used, the amount used is not particularly limited and is appropriately determined depending on the type of reaction substrate used and other reaction conditions, but the concentration of the reaction substrate is usually 0.01 mol or more per liter of solvent. Is preferable, and 0.02 mol or more is more preferable. When the amount of the solvent used is more than this, the productivity is lowered, which is disadvantageous.

  The reactor used in the present invention has two or more locations for introducing the reaction gas into the reaction channel. The reaction gas and the reaction gas react in the reaction field. Of these, the first reaction gas introduction part is preferably closer to the reaction liquid introduction part from the viewpoint of lengthening the gas-liquid reaction field. The reaction gas introduced here is set so that at least the ratio of the segment length of the reaction gas in the flow direction to the equivalent diameter of the flow path in the reaction field is 0.75 or more, and preferably 1.0 or more. The ratio of the segment length of the reaction gas to the equivalent diameter of the flow path is preferably 100 or less, and more preferably 50 or less. If the segment length is too short, the flow format becomes unstable and the rapid mass transfer between gas and liquid, which is a characteristic of alternating flow, may not be obtained, leading to a decrease in productivity. Therefore, the desired reaction rate may not be obtained.

  The second reaction gas introduction part is set so that the ratio of the reaction gas segment length in the flow direction to the equivalent diameter of the flow channel in the reaction field is 0.75 or more in the reaction field, 1.0 or more is preferable. The ratio of the segment length of the reaction gas to the equivalent diameter of the flow path is preferably 100 or less, and more preferably 50 or less. If the segment length is too short, the flow format becomes unstable and the rapid mass transfer between gas and liquid, which is a characteristic of alternating flow, may not be obtained, leading to a decrease in productivity. Therefore, the desired reaction rate may not be obtained.

  Examples of the gas-liquid multiphase flow that circulates include alternating flow (slag flow, plug flow), bubble flow, churn flow, annular flow, etc., in which gas and liquid segments flow alternately, but satisfy the cross section of the flow reactor The alternating flow in which the segments are generated is preferable because it promotes mass transfer between the gas and liquid.

  The reaction liquid may be introduced into only a single flow path or divided into a plurality of flow paths, and the raw material solution and the catalyst solution may be introduced at a time or in a plurality of times.

  The number of reaction gas introductions according to the present invention may be any number of times as long as it is 2 times or more. However, if the number is too large, internal pressure control and piping become complicated, which is not preferable. Usually, the number of reaction gas introductions is preferably 2 to 50, more preferably 2 to 10.

  The reaction pressure is not particularly limited, but it is preferably carried out under normal pressure or increased pressure. When molecular oxygen is used as the oxidizing agent, it is more preferably under pressure.

  The reaction temperature is not particularly limited, but is usually −50 ° C. or higher, preferably −30 ° C. or higher, more preferably −10 ° C. or higher, and usually 500 ° C. or lower, preferably 400 ° C. or lower, more preferably 300 ° C. or lower. .

  The flow rate condition is not particularly limited as long as the flow type is set to be an alternating flow. Usually, the flow rate at each reaction temperature of liquid and gas is preferably 100 m / min or less, more preferably 50 m / min or less. The flow rate of each of the liquid and gas is preferably 0.0001 m / min or more, and more preferably 0.0005 / min or more.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples.

(Analysis of raw materials and products)
Gas chromatography (GC) equipped with an FID detector was used for analysis of raw materials and products.

When the charged raw material is A (mol) and the product detected from the solution after the reaction is B (mol), the yield Y (%) of the product is expressed as follows.
Y (%) = 100 × B / A

[Example 1]
For the reaction, ethyl lactate was used as the alcohol to be oxidized. The product after oxidation in this reaction is ethyl pyruvate. As the reaction tube, a PTFE tube reactor having an inner diameter of 1 mm and an outer diameter of 1.54 mm was used. 2.100 g of ethyl lactate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 100 mL of acetonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction solvent to prepare a solution A. Further, 0.17 g of vanadium oxytrichloride (manufactured by Wako Pure Chemical Industries, Ltd.) (5 mol% with respect to the same amount of lactic acid ester in the liquid A) was added to 100 mL of acetonitrile as a reaction solvent to prepare a liquid B.

  Liquid A and liquid B were circulated through a PTFE tube having an inner diameter of 1 mm and an outer diameter of 1.54 mm at a flow rate of 1 mL / min, and merged with a 1/16 inch union tee. After the merging, the mixture was contracted into a PTFE tube having an inner diameter of 0.5 mm for mixing. Further, pure oxygen was joined to this tube at a flow rate of 1.5 cc / min using a union tee. The channel length (reaction field I) after the outlet of the union tee into which oxygen was introduced was 10 m. Here, as to the distribution form, as a result of taking photographs at various positions of the reaction field I, it was a stable alternating flow at any position. As the reaction progresses, the reaction gas segment length decreases in the gas-liquid alternating flow direction. As a result of taking 20 photographs at the end of the reaction field I, the average segment length at the end is shown. The thickness was 1.4 mm.

  Then, oxygen was introduced a second time with a 1/16 inch union tee. The flow rate of pure oxygen at this time was 1.0 cc / min. The channel length (reaction field II) after the outlet of the union tee where oxygen was introduced for the second time was 10 m. Here, as to the distribution format, as a result of taking photographs at various positions in the reaction field II, it was a stable alternating flow at any position. As the reaction progresses, the reaction gas segment length decreases in the gas-liquid alternating flow direction. As a result of taking 20 photographs at the end of the reaction field II, the average segment length at the end is shown. The thickness was 1.4 mm.

  The shortest segment length in the reaction field was 1.4 mm, and the ratio of the segment length of the reaction gas to the equivalent diameter of the flow path was 1.4.

  The total residence time from the first oxygen introduction to taking the sample was 143 seconds. The temperature of the reaction part was kept constant in a constant temperature bath of 70 ° C. After the reaction, the reaction solution was collected in a sample bottle containing about 1 mL of pure water, the reaction was stopped, and quantitative analysis was performed by GC analysis. The results are shown in Tables 1 and 2.

[Comparative Example 1]
For the reaction, ethyl lactate was used as the alcohol to be oxidized. The product after oxidation in this reaction is ethyl pyruvate as in Example 1. As the reaction tube, a PTFE tube reactor having an inner diameter of 1 mm and an outer diameter of 1.54 mm was used. The concentration and flow rate conditions of the raw material solution (liquid A) and catalyst solution (liquid B) were set in the same manner as in Example 1 and were distributed through a PTFE tube having an inner diameter of 1 mm and an outer diameter of 1.54 mm, and a 1/16 inch union tee. And joined. After the merging, the mixture was contracted into a PTFE tube having an inner diameter of 0.5 mm for mixing. Pure oxygen was further joined to this tube at a flow rate of 2.0 cc / min using a union tee. The channel length (reaction field I) after the outlet of the union tee into which oxygen was introduced was 10, 20, 30, and 40 m. Here, the flow pattern was a stable alternating flow immediately after the introduction of oxygen gas, but as a result of confirmation in the same manner as in Example 1, the alternating flow, the churn flow, the bubble flow, etc. were irregular at a point of 20 m and thereafter. The average flow length was 0.5 mm, and the ratio of the average segment length to the equivalent diameter of the flow path in the reaction field was 0.5. The total residence time from the introduction of oxygen to the collection of the sample was 63 seconds when the reaction field I was 10 m, 252 seconds when 20 m, 470 seconds when 30 m, 715 seconds when 40 m, and 715 seconds when 40 m.

  In the case of 40 m, oxygen was recovered from the reaction tube outlet. The yield corresponding to Example 1 was not obtained. The temperature of the reaction part was kept constant in a constant temperature bath of 70 ° C. After the reaction, the reaction solution was collected in a sample bottle containing about 1 mL of pure water, the reaction was stopped, and quantitative analysis was performed by GC analysis. The results are shown in Tables 1 and 2.

[Comparative Example 2]
The same operation as in Comparative Example 1 was performed except that the introduction amount of pure oxygen was set to a flow rate of 4.0 cc / min. The total residence time from the introduction of oxygen to the collection of the sample was 31 seconds when the reaction field I was 10 m, 80 seconds when 20 m, 147 seconds when 30 m, and 246 seconds when 40 m. The flow path length necessary to obtain the yield corresponding to Example 1 was 30 m. In the case of the flow path length of 40 m where the reaction gas was consumed most, as a result of confirmation in the same manner as in Example 1, the flow format was a stable alternating flow at any position in the reaction field I, and the average segment length was 1 The ratio of the average segment length to the equivalent diameter of the flow path in the reaction field was 1.4. The temperature of the reaction part was kept constant in a constant temperature bath of 70 ° C. After the reaction, the reaction solution was collected in a sample bottle containing about 1 mL of pure water, the reaction was stopped, and quantitative analysis was performed by GC analysis. The results are shown in Tables 1 and 2.

1 A liquid 2 B liquid 3 First oxygen supply port 4 Reaction field I
5 Second oxygen supply port 6 Reaction field II
7 A liquid 8 B liquid 9 First oxygen supply port 10 Reaction field I

Claims (3)

  A method for producing a compound by reacting a reaction substrate and a reaction gas in a flow channel having an equivalent diameter of 1 μm to 5 mm, and introducing the reaction gas into the flow channel from two or more locations, corresponding to the flow channel in the reaction field The manufacturing method of the compound whose ratio of the segment length of the reactive gas with respect to a diameter is 0.75 or more.   The process according to claim 1, wherein the reaction substrate is an alcohol and the product is a compound containing a carbonyl group.   The production method according to claim 2, wherein the reaction gas is a gas containing at least 10% by volume of oxygen.