Method for producing alkylene carbonate, and apparatus for producing alkylene carbonate

Abstract

Provided is a method for producing alkylene carbonate by using a first reaction vessel containing a catalyst-containing reaction liquid and gaseous carbon dioxide, the method comprising: a step (A) for supplying an alkylene oxide-containing raw material liquid through a nozzle so that the raw material liquid moves to a lower portion of the first reaction vessel along the inner surface from an upper portion of the first reaction vessel, and supplying the raw material liquid with dissolved carbon dioxide in the first reaction vessel to the reaction liquid; and a step (B) for reacting alkylene oxide and carbon dioxide in the catalyst-containing reaction liquid at the lower portion of the first reaction vessel to obtain alkylene carbonate, wherein the ratio (DL / DT) of the height DL from the liquid level in the first reaction vessel to the discharge port of the nozzle to the height DT from the bottom tangent line of the first reaction vessel to the discharge port of the nozzle is 0.1-0.7.

Description

[Technical Field]

[0001] This invention relates to a method for producing alkylene carbonates and an apparatus for producing alkylene carbonates. [Background technology]

[0002] The reaction to obtain alkylene carbonates from alkylene oxide and carbon dioxide has been extensively studied due to its usefulness, and active research is being conducted on catalysts to obtain industrially sufficient reaction rates. Many reports have been published using solid acid catalysts, alkali metal salt catalysts, homogeneous organometallic catalysts, etc. For example, there are methods for producing alkylene carbonates using a carboxylic acid-type cation exchange resin with an alkyl-substituted ammonium cation as a countercation (Patent Document 1), methods for producing alkylene carbonates using a catalyst made of tungsten oxide or molybdenum oxide (Patent Document 2), methods for producing alkylene carbonates using an anion exchange resin having a tertiary amine functional group or a quaternary ammonium functional group as a catalyst (Patent Document 3), synthesis of aryl-substituted alkylene carbonates using an alkali metal salt catalyst (Patent Document 4), methods for producing alkenyl ether carbonates using a phase-transfer organometallic complex catalyst (Patent Document 5), and methods for producing alkylene carbonates from alkylene oxide and carbon dioxide in the presence of an alkali halogenated catalyst (Patent Document 6). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-206846 [Patent Document 2] Japanese Patent Application Publication No. 7-206847 [Patent Document 3] Japanese Patent Application Publication No. 7-206848 [Patent Document 4] Japanese Patent Application Publication No. 8-53396 [Patent Document 5] U.S. Patent No. 5,095,124 [Patent Document 6] Japanese Patent Publication No. 2006-104092 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a method and apparatus for producing alkylene carbonate using alkylene oxide and carbon dioxide as raw materials, exhibiting a high alkylene oxide conversion rate. [Means for solving the problem]

[0005] As a result of diligent research to solve the above problems, the inventors of the present invention have found that by setting the ratio of the height DL from the liquid surface in the reaction vessel to the discharge port of the nozzle supplying the raw material liquid to a predetermined range, a reaction exhibiting a high alkylene oxide conversion rate can be achieved, leading to the present invention. The present invention encompasses the following embodiments. <1> A method for producing alkylene carbonate using a first reaction vessel containing a reaction solution containing a catalyst and gaseous carbon dioxide, Step (A) involves supplying a raw material solution containing alkylene oxide through a nozzle so that it moves from the top of the first reaction vessel along its inner surface to the bottom of the first reaction vessel, and supplying the raw material solution containing dissolved carbon dioxide from the first reaction vessel to the reaction solution. (B) A step of reacting alkylene oxide with carbon dioxide in a reaction solution containing the catalyst at the bottom of the first reaction vessel to obtain alkylene carbonate, Includes, A method for producing alkylene carbonate, wherein the ratio (DL / DT) of the height from the liquid level in the first reaction vessel to the nozzle outlet to the height DT from the bottom tangent line of the first reaction vessel to the nozzle outlet is 0.1 to 0.7. <2> Using two or more of the aforementioned nozzles, <1> A method for producing the alkylene carbonate described above. <3> The reaction liquid contained in the first reaction vessel is withdrawn from the bottom of the first reaction vessel, and a portion of it is supplied into the first reaction vessel as the raw material liquid. The number of cycles of the reaction solution per unit time is 10 to 70 times / hour. <1> or <2> A method for producing alkylene carbonate as described in [the relevant document]. <4> The operating pressure of the first reaction vessel is 4 to 12 MPa. <1> ~ <3> A method for producing alkylene carbonate as described in any of the above. <5> The ratio (DL / DT) is between 0.20 and 0.60. <1> ~ <4> A method for producing alkylene carbonate as described in any of the above. <6> The height / inner diameter ratio of the first reaction vessel is 3 to 7, and the inner diameter is 1 to 4 m. <1> ~ <5> A method for producing alkylene carbonate as described in any of the above. <7> The alkylene oxide is ethylene oxide, and the alkylene carbonate is ethylene carbonate. <1> ~ <6> A method for producing alkylene carbonate as described in any of the above. <8> The process includes step (C) of reacting the reaction solution obtained in step (B) with alkylene oxide and carbon dioxide in a second reaction vessel to obtain alkylene carbonate. <1> ~ <7> A method for producing alkylene carbonate as described in any of the above. <9> The process includes step (D) of further reacting the reaction solution obtained in step (C) with alkylene oxide and carbon dioxide in a third reaction vessel to obtain alkylene carbonate. <8> A method for producing alkylene carbonate as described in [the relevant document]. <10> In step (A) above, the raw material liquid is supplied by spraying it onto the wall surface using a nozzle. <1> ~ <9> A method for producing alkylene carbonate as described in any of the above. <11> A first reaction vessel containing a reaction solution including a catalyst, A nozzle for supplying a raw material liquid containing an alkylene oxide so as to move from the upper part of the first reaction vessel along the inner surface to the lower part of the first reaction vessel, A carbon dioxide supply unit for introducing carbon dioxide into the first reaction vessel, and a manufacturing apparatus for alkylene carbonate comprising the same, An alkylene carbonate manufacturing apparatus in which the ratio (DL / DT) of the height DL from the liquid surface in the reaction vessel to the discharge port of the nozzle to the height DT from the bottom tangent line of the first reaction vessel to the discharge port of the nozzle is operationally controlled to be 0.1 to 0.7. <12> A second reaction vessel containing a reaction liquid containing a catalyst, A nozzle for supplying the reaction liquid from the first reaction vessel as a raw material liquid so as to move from the upper part of the second reaction vessel along the inner surface to the lower part of the second reaction vessel, A carbon dioxide supply unit for introducing carbon dioxide into the second reaction vessel, and the alkylene carbonate manufacturing apparatus according to <11>, further comprising the same. <13> The alkylene carbonate manufacturing apparatus according to <11> or <12>, further comprising a third reaction vessel into which the reaction liquid is introduced from the second reaction vessel and in which the alkylene oxide and carbon dioxide are further reacted. <14> The alkylene carbonate manufacturing apparatus according to any one of <11> to <13>, wherein the ratio (DL / DT) is 0.10 to 0.40. <15> The alkylene carbonate manufacturing apparatus according to any one of <11> to <14>, wherein the nozzle supplies the raw material liquid by spraying it against the wall surface.

Advantages of the Invention

[0006] <C The present invention can provide a method and an apparatus for manufacturing alkylene carbonate which use alkylene oxide and carbon dioxide as raw materials and exhibit a high alkylene oxide conversion rate.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 is a schematic diagram of the alkylene carbonate manufacturing apparatus 1 according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram of the alkylene carbonate manufacturing apparatus 10 according to the second embodiment. [Modes for carrying out the invention]

[0008] The embodiments of the present invention (hereinafter referred to as "these embodiments") will be described in detail below, with reference to the drawings as necessary. However, the present invention is not limited thereto, and various modifications are possible without departing from its essence. In the drawings, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to those shown.

[0009] The method for producing alkylene carbonate according to this embodiment uses a first reaction vessel containing a reaction solution including a catalyst and gaseous carbon dioxide, Step (A) involves supplying a raw material solution containing alkylene oxide through a nozzle so that it moves from the top of the first reaction vessel along its inner surface to the bottom of the first reaction vessel, and supplying the raw material solution containing dissolved carbon dioxide from the first reaction vessel to the reaction solution. (B) A step of reacting alkylene oxide with carbon dioxide in a reaction solution containing the catalyst at the bottom of the first reaction vessel to obtain alkylene carbonate, Includes, The ratio (DL / DT) of the height DL from the liquid level in the reaction vessel to the nozzle outlet to the height DT from the bottom tangent line of the first reaction vessel to the nozzle outlet is 0.1 to 0.7.

[0010] With the above configuration, it is possible to provide a method for producing alkylene carbonate using alkylene oxide and carbon dioxide as raw materials, exhibiting a high alkylene oxide conversion rate. In the production method according to this embodiment, the raw material liquid containing alkylene oxide is supplied by a nozzle so that it moves from the top of the reaction vessel along the inner surface to the bottom of the reaction vessel. As the reaction liquid spreads on the walls, the raw material liquid absorbs the carbon dioxide present in the reaction vessel and supplies it to the reaction liquid at the bottom of the reaction vessel. This is thought to increase the concentration of carbon dioxide in the reaction liquid, making it easier to obtain the desired alkylene carbonate. In particular, it is presumed that by operating with a ratio (DL / DT) within a predetermined range, the balance between the amount of carbon dioxide absorbed by the raw material liquid and the efficiency of the reaction is improved, enabling a reaction that exhibits a high alkylene oxide conversion rate. It should be noted that the above is a speculation on the mechanism by which the effects of the production method according to this embodiment are obtained, and the present invention is not limited thereto.

[0011] The method for producing alkylene carbonate according to this embodiment includes, in addition to steps (A) and (B), The process may also include step (C) in which the reaction solution obtained in step (B) is reacted with alkylene oxide and carbon dioxide in a second reaction vessel to obtain alkylene carbonate.

[0012] Furthermore, process (C) is, Step (C-1) involves supplying the reaction liquid obtained in step (B) as a raw material liquid via a nozzle so that it moves from the top of the second reaction vessel, which contains a reaction liquid including a catalyst and gaseous carbon dioxide, down the inner surface to the bottom of the second reaction vessel, and supplying the raw material liquid containing dissolved carbon dioxide from the second reaction vessel to the reaction liquid, The process may also include a step (C-2) of reacting alkylene oxide with carbon dioxide in a reaction solution containing the catalyst at the bottom of the second reaction vessel to obtain alkylene carbonate.

[0013] The method for producing alkylene carbonate according to this embodiment includes, in addition to steps (A), (B), and (C), The process may also include step (D), in which the reaction solution obtained in step (C) is further reacted with alkylene oxide and carbon dioxide in a third reaction vessel to obtain alkylene carbonate. By including the above configuration, the method for producing alkylene carbonate according to this embodiment can further increase the conversion rate of alkylene oxide.

[0014] <Raw material liquid> The raw material solution contains alkylene oxide. An example of the alkylene oxide is the compound represented by the following formula (1). [ka] (In the formula, R 1 , R 2 , R 3 and R 4 (Each represents independently a hydrogen atom, a linear hydrocarbon group with 1 to 8 carbon atoms, an alicyclic hydrocarbon group with 3 to 8 carbon atoms, or an aromatic hydrocarbon group with 6 to 8 carbon atoms.)

[0015] More specifically, examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, vinylethylene oxide, cyclohexene oxide, and styrene oxide. Among these, ethylene oxide and propylene oxide are preferred from the viewpoint of availability.

[0016] In the method for producing alkylene carbonate according to this embodiment, in the step of obtaining alkylene carbonate, alkylene oxide is reacted with carbon dioxide in the presence of a catalyst to obtain alkylene carbonate (cyclic alkylene carbonate) represented by the following formula (2). [ka] (R in the formula) 1 , R 2 , R 3 and R 4 This is as defined in equation (1).

[0017] In this embodiment, specific examples of the alkylene carbonate are not particularly limited, and examples thereof include ethylene carbonate, propylene carbonate, butylene carbonate, vinyl ethylene carbonate, cyclohexene carbonate, and styrene carbonate. Ethylene carbonate and propylene carbonate are preferred.

[0018] In the method for producing an alkylene carbonate, the reaction for obtaining an alkylene carbonate from an alkylene oxide and carbon dioxide is represented by the following formula (3). [Chemical formula] (In the formula, R 1 , R 2 , R 3 and R 4 are as defined in formula (1).)

[0019] The catalyst used in the above reaction is not particularly limited as long as it is a catalyst used for carrying out the reaction of the above formula (3). Specifically, organic substance-based catalysts such as tetraethylammonium bromide, halides of 5-membered ring / 6-membered ring hydrocarbons, rhodan ammonium or its thermal decomposition products, inorganic substance-based catalysts such as bromides or iodides of metals or alkali metals, and those obtained by adding a small amount of alcohols or water to these are used. However, an inorganic substance-based catalyst that is easy to recover is preferred. The amount of the catalyst used is not particularly limited, but is preferably 0.1 to 3% by mass, and more preferably 0.1 to 2% by mass, based on the raw material liquid.

[0020] [First Embodiment] [Production Apparatus for Alkylene Carbonate] FIG. 1 is a schematic configuration diagram of a production apparatus 1 for an alkylene carbonate according to the first embodiment. The production apparatus 1 for an alkylene carbonate according to this embodiment includes a first reaction vessel 2, a nozzle 3 for supplying a raw material liquid, and a carbon dioxide supply unit 4 for introducing carbon dioxide.

[0021] The first reaction vessel 2 may be a reaction system such as a complete mixing reactor. A complete mixing reactor may be equipped with a Venturi stirrer.

[0022] The first reaction vessel 2 contains the reaction solution containing the catalyst. The reaction solution is stored in the lower part of the first reaction vessel 2 and may be stirred with a stirrer (not shown). Carbon dioxide is also introduced into the first reaction vessel 2 from the carbon dioxide supply unit 4. High concentrations of gaseous carbon dioxide are present in the upper part of the first reaction vessel 2.

[0023] The nozzle 3 preferably has a structure suitable for dissolving carbon dioxide in the raw material liquid, for example, a shower nozzle type.

[0024] The nozzle 3 may be connected to the catalyst supply unit 5 and the alkylene oxide supply unit 6, and configured to supply a raw material liquid containing a mixture of catalyst and ethylene oxide. The catalyst is also mixed into the raw material liquid after being adjusted to a predetermined concentration.

[0025] The nozzle 3 is installed on top of the first reaction vessel 2 and is positioned to supply the raw material liquid to the inner wall surface of the first reaction vessel 2. It is preferable to have two or more nozzles 3. By having multiple nozzles 3, the raw material liquid can spread across the inner surface of the reaction vessel, thereby increasing the carbon dioxide absorption efficiency.

[0026] The height-to-inner-diameter ratio of the reaction vessel is preferably 3 to 7, more preferably 4 to 6, and even more preferably 4.5 to 5.5. Here, the height of the reaction vessel refers to the distance between the upper and lower tangent lines. The inner diameter of the reaction vessel is preferably 1 to 4 m, more preferably 1.2 to 3.0 m, and even more preferably 1.5 to 2.5 m.

[0027] As shown in Figure 1, the alkylene carbonate production apparatus preferably has a circulation circuit 7 for reuse of the reaction liquid from the first reaction vessel 2 as a raw material liquid. The circulation circuit 7 is equipped with an external pump 9 and is configured to circulate the reaction liquid. Although not shown, a backup external pump 9 may also be provided. The circulation circuit 7 is preferably connected to the process-side flow path of the heat exchanger 8 via piping. The heat exchanger 8 preferably has a heat exchange-side flow path for flowing a heat exchange medium whose temperature has been adjusted to a predetermined temperature range, and a process-side flow path for flowing a process liquid in which heat exchange is performed in connection with the production of alkylene carbonate. The process liquid is a liquid that is treated (i.e., whose temperature is adjusted) by the heat exchanger, and the heat exchange medium is a medium for adjusting the temperature of the process liquid. The heat exchange-side flow path of the heat exchanger is a flow path for the heat exchange medium, and the process-side flow path is a flow path for the process liquid.

[0028] The heat exchanger 8 is preferably one that can maintain the internal temperature of the process-side flow path at 135°C to 200°C by flowing a heat exchange medium with a temperature of 140°C to 200°C through the heat exchange-side flow path of the heat exchanger. For example, a coiled tube heat exchanger, a double-tube heat exchanger, or a general multi-tube heat exchanger installed inside the reactor can be used individually or in combination. It is preferable to use a multi-tube heat exchanger, which allows for a larger heat transfer area and miniaturization of the device.

[0029] When using a multi-tube heat exchanger, the process fluid and heat exchange medium can be routed through either the tube side or the shell side of the multi-tube heat exchanger, with the latter being the heat exchange side or the process side. The fluids flowing through the tube side and the shell side of the heat exchanger can be selected as needed, for example, to increase the overall heat transfer coefficient (U) when using a small heat exchanger, or to facilitate cleaning by flowing a fluid that easily attracts fouling substances through the tube side.

[0030] The heat exchanger 8 is preferably a device that functions as both a preheater and a cooler. Such a heat exchanger can be used as a preheater to raise the reaction mixture to the reaction start temperature during startup, and as a cooler to remove the heat of reaction during steady-state operation. The material of the process-side flow path of the heat exchanger 8 is not particularly limited as long as it has corrosion resistance to the process fluid. Since iron rust causes the formation of alkylene oxide polymers due to its catalytic action, stainless steel is preferable.

[0031] <Method for producing alkylene carbonate> The method for producing alkylene carbonate according to this embodiment will be described below, using the operation of the alkylene carbonate production apparatus 1 as an example. The catalyst and alkylene oxide are supplied from the catalyst supply unit 5 and the alkylene oxide supply unit 6, respectively, to obtain a raw material solution containing these. Here, the amount of catalyst supplied may be adjusted to obtain a raw material solution with a desired catalyst concentration.

[0032] Next, nozzle 3 supplies the raw material liquid so that it moves from the top of the first reaction vessel 2 down the inner surface to the bottom of the first reaction vessel 2. As the raw material liquid moves along the inner surface, it spreads out on a flat surface, forming a liquid film, and gaseous carbon dioxide dissolves into the raw material liquid. The raw material liquid with dissolved carbon dioxide flows into the reaction solution containing the catalyst and is mixed, thereby supplying alkylene oxide and carbon dioxide into the reaction solution. Through the above operations, step (A) described above is carried out.

[0033] In step (A), it is preferable to supply the raw material liquid by spraying it onto the wall surface using nozzle 3. By adjusting the direction of nozzle 3 in this way, the raw material liquid can move along the inner surface of the reactor.

[0034] The ratio of the distance from the nozzle 3 outlet to the wall to the inner diameter of the reactor (distance between nozzle 3 outlet and wall / inner diameter of reactor) is preferably 0.30 or less, more preferably 0.20 or less, and even more preferably 0.10 or less. Note that the distance from the nozzle 3 outlet to the wall refers to the distance from the nozzle outlet to the wall in the direction of the raw material liquid injection axis of the nozzle 3 nozzle opening. For example, if the nozzle 3 nozzle opening is not facing the wall, the distance from the nozzle outlet to the wall cannot be defined.

[0035] As shown in Figure 1, in the alkylene carbonate production method according to this embodiment, the ratio (DL / DT) of the height DL from the liquid surface in the reaction vessel to the nozzle outlet to the height DT from the bottom tangent line of the first reaction vessel 2 to the nozzle outlet is 0.1 to 0.7. The ratio (DL / DT) is preferably 0.10 to 0.60, more preferably 0.10 to 0.50, even more preferably 0.10 to 0.45, and even more preferably 0.10 to 0.40. As the value of the ratio (DL / DT) decreases, the space at the top of the first reaction vessel 2 decreases, making it more difficult to absorb carbon dioxide. In the present invention, by supplying the raw material liquid from the top of the first reaction vessel through the nozzle so that it moves along the inner surface to the bottom of the first reaction vessel, a sufficient amount of carbon dioxide can be absorbed into the raw material liquid by ensuring a residence time in the upper space. On the other hand, a smaller ratio (DL / DT) means that the liquid level in the first reaction vessel 2 will be higher. Within the aforementioned range of ratio (DL / DT), sufficient reaction time can be ensured after the raw material liquid is introduced into the liquid phase, resulting in a high alkylene oxide conversion rate.

[0036] The bottom tangent line refers to the height at the boundary between the straight and curved sections of the reaction vessel. If multiple nozzles 3 are provided, DT is the average height from the bottom tangent line of the first reaction vessel 2 to the discharge port of each nozzle, and DL is the average height from the liquid level in the reaction vessel to the discharge port of each nozzle.

[0037] In the manufacturing apparatus according to this embodiment, the operation is controlled so that the ratio (DL / DT) is between 0.1 and 0.7. This can be achieved, for example, by cascade control based on the liquid level in the reactor measured by a liquid level gauge and the discharge flow rate from the reactor.

[0038] Furthermore, the above-described step (B) is carried out in the reaction liquid at the bottom of the first reaction vessel 2.

[0039] The reaction temperature in step (B) is preferably 100 to 250°C, more preferably 150 to 200°C, and even more preferably 160 to 190°C.

[0040] The average residence time in the reaction vessel in step (B) is preferably 10 minutes to 6 hours, more preferably 30 minutes to 3 hours, and more preferably 1 to 2 hours.

[0041] The operating pressure of the first reaction vessel 2 is preferably 4 to 12 MPa, more preferably 5 to 11 MPa, and even more preferably 8 to 10 MPa.

[0042] It is preferable that the reaction liquid contained in the first reaction vessel 2 is withdrawn from the bottom of the first reaction vessel 2, and a portion of it is supplied into the first reaction vessel 2 as a raw material liquid. In other words, it is preferable that the reaction liquid is circulated as a raw material liquid via the circulation circuit 7 and the external pump 9.

[0043] In this case, the number of times the reaction solution is circulated per unit time is preferably 10 to 70 times / hr, and more preferably 20 to 50 times / hr. The number of circulations refers to the number of times the reaction solution in the reaction vessel is replaced per hour, and is represented by the following formula (A). Circulation cycles = Circulation flow rate of the external pump / Volume of the liquid phase at the bottom of the reactor (A)

[0044] When circulating the reaction solution, if a heat exchanger is installed in the middle of the piping to remove the reaction heat, it is preferable to circulate at a high flow rate because this increases the cooling capacity of the heat exchanger.

[0045] The method for producing alkylene carbonate according to this embodiment is preferably carried out on an industrial scale. In this specification, industrial scale means a scale at which alkylene carbonate is produced at a rate of 1 ton / hour or more, preferably 2 ton / hour or more, more preferably 3 ton / hour or more, and even more preferably 4 ton / hour or more. The upper limit of industrial scale is not particularly limited, but for example, it is 15 ton / hour or less.

[0046] [Second Embodiment] Figure 2 is a schematic diagram of the alkylene carbonate production apparatus 10 according to the second embodiment. Components common to the alkylene carbonate production apparatus 1 are denoted by the same reference numerals and their descriptions are omitted. The characteristic configuration of the alkylene carbonate production apparatus 10 will be described below. The alkylene carbonate production apparatus 10 further has a second reaction vessel 11 and a third reaction vessel 22 downstream of the first reaction vessel 2.

[0047] The alkylene carbonate production apparatus 10 according to this embodiment includes a second reaction vessel 11 in addition to the configuration shown in the alkylene carbonate production apparatus 1. The second reaction vessel 11 contains a reaction liquid containing a catalyst. The second reaction vessel 11 includes a nozzle 12 that supplies the reaction liquid from the first reaction vessel 2 as a raw material liquid so that it moves from the top of the second reaction vessel 11 along its inner surface to the bottom of the second reaction vessel 11, and a carbon dioxide supply unit 16 that introduces carbon dioxide into the second reaction vessel 11.

[0048] In the second reaction vessel 11, the reaction solution from the first reaction vessel 2 is supplied by a nozzle so that it moves from the top of the second reaction vessel 11 along the inner surface to the bottom of the reaction vessel, and the raw material solution containing dissolved carbon dioxide from the second reaction vessel 11 is supplied to the reaction solution to further advance the reaction between alkylene oxide and carbon dioxide. Through the above operation, the above-described steps (C) (steps (C-1) and (C-2)) are carried out. In the second reactor 11, carbon dioxide may be supplied from the carbon dioxide supply unit 16, but since a sufficient amount of carbon dioxide is dissolved in the reaction solution in the first reactor 2, if the carbon dioxide concentration in the reaction solution becomes low, carbon dioxide may be supplied from the carbon dioxide supply unit 16 as appropriate.

[0049] In the alkylene carbonate production method according to this embodiment, the ratio (DL' / DT') of the height DL' from the liquid surface in the second reaction vessel 11 to the discharge port of the nozzle to the height DT' from the bottom tangent line of the second reaction vessel 11 to the discharge port of the nozzle 12 is preferably 0.1 to 0.7, more preferably 0.15 to 0.60, and even more preferably 0.20 to 0.50. If multiple nozzles 12 are provided, DT' is the average height from the bottom tangent line of the second reaction vessel 11 to the discharge port of each nozzle, and DL' is the average height from the liquid level in the reaction vessel to the discharge port of each nozzle.

[0050] As shown in Figure 2, the alkylene carbonate production apparatus 10 preferably has a circulation circuit 14 for reuse of the reaction liquid from the second reaction vessel 11 as a raw material. The circulation circuit 14 may include a heat exchanger 13 and an external pump 15. Although not shown, a backup external pump 15 may be provided. The circulation circuit 14 is preferably connected to the process-side flow path of the heat exchanger 13 via piping. By having the circulation circuit 14, some of the excess carbon dioxide is released from the second reaction vessel 11.

[0051] The reaction temperature in the second reaction vessel 11 is preferably 100 to 250°C, more preferably 150 to 200°C, and even more preferably 160 to 190°C.

[0052] The average residence time in the second reaction vessel 11 is preferably 10 minutes to 6 hours, more preferably 30 minutes to 4 hours, and more preferably 2 to 3 hours.

[0053] The operating pressure in the second reaction vessel 11 is preferably 4 to 12 MPa, more preferably 4 to 8 MPa, and even more preferably 4.5 to 6.5 MPa.

[0054] It is preferable that the reaction liquid contained in the second reaction vessel 11 is withdrawn from the bottom of the second reaction vessel 11, and a portion of it is supplied into the second reaction vessel 11 as a raw material liquid. In other words, it is preferable to circulate the reaction liquid as a raw material liquid via the circulation circuit 14 and the external pump 15.

[0055] In this case, the number of times the reaction solution is circulated per unit time is preferably 10 to 70 times / hour, and more preferably 15 to 35 times / hour.

[0056] The alkylene carbonate production apparatus 10 according to this embodiment includes a third reaction vessel 22 located downstream of the second reaction vessel 11, into which the reaction solution is introduced from the second reaction vessel 11 and further reacted with alkylene oxide and carbon dioxide. The third reaction vessel 22 carries out the reaction between unreacted alkylene oxide and dissolved carbon dioxide, and the reaction solution obtained in step (C) is further reacted with alkylene oxide and carbon dioxide in the third reaction vessel 22 to obtain alkylene carbonate. Step (D) described above is carried out by the above operation. The third reaction vessel 22 is preferably a full-liquid reactor such as a plug-flow type reactor that does not have external circulation.

[0057] The reaction temperature in the third reaction vessel 22 is preferably 100 to 250°C, more preferably 150 to 200°C, and even more preferably 160 to 190°C.

[0058] The operating pressure in the third reaction vessel 22 is preferably 4 to 12 MPa, more preferably 4 to 8 MPa, and even more preferably 4.5 to 6.5 MPa. [Examples]

[0059] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to the following examples.

[0060] [Example 1] Ethylene carbonate was produced using the alkylene carbonate production apparatus 10 shown in Figure 2. The first reaction vessel 2 had an inner diameter of 1.8 mφ, a straight section length of 8.7 m, and a capacity of 23.6 m³. 3 The first reaction vessel 2 is a vertical cylindrical stainless steel tank in which a distributor with 10 nozzles 3 is positioned 8.4 m (DT) from the tangent line at the bottom of the first reaction vessel 2, for the purpose of liquid dispersion to improve the absorption efficiency of carbon dioxide gas. It is connected to the process-side flow path of the heat exchanger 8 via piping to form a circulation circuit 7.

[0061] As one of the raw materials, ethylene oxide cooled to approximately 5°C was supplied from the alkylene oxide supply unit 6 to the first reaction vessel 2 at a rate of 4,780 kg / hr. For the other raw material, carbon dioxide, liquefied carbon dioxide was gasified in a carbon dioxide evaporator (not shown) and supplied from the carbon dioxide supply unit 4 to the first reaction vessel 2, adjusted to a constant pressure of approximately 9.5 MPa at a temperature of approximately 90°C. The average carbon dioxide supply rate was 4,920 kg / hr.

[0062] Potassium iodide (KI) was used as the catalyst, and it was prepared in an ethylene carbonate solution at a concentration of 5% by mass. The catalyst solution was prepared by mixing 9 parts by mass of recovered catalyst (obtained after the purification of the ethylene carbonate product) with 1 part by mass of fresh catalyst solution, and this mixture was supplied to the wall of the first reaction vessel 2 via nozzle 3. The supply rate of the catalyst solution was set to 560 kg / hr using pump 3 so that the potassium iodide concentration in the circulating liquid (reaction system) was 0.23-0.26% by mass.

[0063] The reaction mixture was discharged from the first reaction vessel 2 so that the distance (DL) from the liquid surface in the first reaction vessel 2 to the nozzle 3 remained constant at 2.9 m. The discharge rate of the reaction mixture was adjusted using a discharge control valve (not shown). (Ratio (DL / DT) = 0.35)

[0064] The production of ethylene carbonate was carried out under conditions where the reaction temperature, measured by a thermometer installed at the bottom of the first reaction vessel 2, was 180°C. During the reaction, the reaction liquid was circulated through a circulation circuit 7, which included the first reaction vessel 2 and the process-side flow path of the heat exchanger 8, while a heat exchange medium was flowed through the heat exchange-side flow path of the heat exchanger 8. Specifically, the reaction liquid was withdrawn from the outlet of the first reaction vessel 2, pressurized by an external pump 9, and sent to the heat exchanger 8. The reaction mixture, whose temperature was adjusted in the heat exchanger 8, was then returned to the reaction vessel 2 through its inlet, thus circulating within the circulation circuit. The circulation rate of the reaction liquid in the first reaction vessel 2 was monitored by a circulation flow meter (not shown) and adjusted to remain constant at approximately 550 tons / hour. The liquid volume was 17.5 tons, the average residence time in the first reaction vessel 2 was 1.7 hours, and the circulation rate was 44 times / hour.

[0065] The reaction liquid withdrawn from the circulation circuit 7 of the first reaction vessel 2 is supplied to the second reaction vessel 11, which has an inner diameter of 2.3 mφ, a straight body length of 6.5 m, and a capacity of 33.4 m³. 3 The reaction vessel is a vertical cylindrical stainless steel tank with a distributor equipped with 10 nozzles, positioned 6.2 m from the tangent line at the bottom of the second reaction vessel 11, for the purpose of liquid dispersion to improve the absorption efficiency of carbon dioxide gas. It is connected to the process-side flow path of the heat exchanger 13 via piping, forming a circulation circuit 14. The circulation rate was adjusted to a constant of approximately 405 tons / hr. The reaction temperature was controlled to 180°C as measured by a thermometer installed at the bottom of the second reaction vessel 11, and the reaction pressure was controlled to 5.1 MPa. The reaction mixture was discharged from the second reaction vessel 11 so that the distance from the liquid surface in the second reaction vessel 11 to the nozzle 12 distributor remained constant at 3.1 m. (Ratio (DL' / DT') = 0.50)

[0066] Furthermore, the reaction liquid withdrawn from the circulation circuit 14 of the second reaction vessel 11 is supplied to the third reaction vessel 22, which has an inner diameter of 0.9 mφ, a straight body length of 9.0 m, and a capacity of 6.1 m³. 3 This is a plug-flow type reactor. The reaction temperature was controlled to 180°C, as measured by a thermometer installed at the bottom of the third reaction vessel 22, and the reaction pressure was controlled to 5.1 MPa.

[0067] Under the above conditions, we achieved stable manufacturing results by conducting 180 days of continuous operation. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 8,930 kg / hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 88.6%. Furthermore, the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 99.3%.

[0068] [Example 2] Ethylene carbonate was produced in the same manner as in Example 1, except that the distance (DT) from the liquid surface in the first reaction vessel 2 to the supply position of the nozzle 3 was set to 4.2 m. (Ratio (DL / DT) = 0.50) The liquid volume was 15.4 tons, the average residence time in the first reaction vessel 2 was 1.4 hours, and the circulation rate was 52 times / hour. Under the above conditions, continuous operation was carried out for 180 days, achieving stable production results. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 8,730 kg / hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 86.5%. Furthermore, the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 99.2%.

[0069] [Example 3] Ethylene carbonate was produced in the same manner as in Example 1, except that the distance (DT) from the liquid surface in the first reaction vessel 2 to the supply position of the nozzle 3 was set to 5.5 m (ratio (DL / DT) = 0.65). The liquid volume was 11.0 tons, the average residence time in the reaction vessel was 1.0 Hr, and the circulation rate was 70 times / Hr. Under the above conditions, we achieved stable manufacturing results by conducting 180 days of continuous operation. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 8,531 kg / hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 84.5%. Furthermore, the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 99.1%.

[0070] [Example 4] Ethylene carbonate was produced in the same manner as in Example 1, except that the number of nozzles 3 in the first reaction vessel 2 was set to one. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 8,440 kg / hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 83.5%. The conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 99.0%.

[0071] [Comparative Example 1] Ethylene carbonate was produced in the same manner as in Example 1, except that the distance from the liquid surface in the first reaction vessel 2 to the supply position (DT) of the nozzle 3 was set to 0.2 m (ratio (DL / DT) = 0.02). The liquid volume was 27.5 tons, the average residence time in the reaction vessel was 2.7 hours, and the circulation rate was 28 times / hour. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 8,330 kg / hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 82.4%. Furthermore, the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 98.9%.

[0072] [Comparative Example 2] Ethylene carbonate was produced in the same manner as in Example 1, except that the distance from the liquid surface in the first reaction vessel 2 to the supply position (DT) of the nozzle 3 was set to 6.7 m (ratio (DL / DT) = 0.80). The liquid volume was 7.1 tons, the average residence time in the first reaction vessel 2 was 0.7 Hr, and the circulation rate was 108 times / Hr. The yield of ethylene carbonate at the outlet of the third reaction vessel 22 was 7,840 kg / Hr, and the conversion rate from ethylene oxide to ethylene carbonate at the outlet of the first reaction vessel 2 was 77.3%. The conversion rate from ethylene oxide to ethylene carbonate at the outlet of the third reaction vessel 22 was 99.0%. [Industrial applicability]

[0073] The present invention can be suitably used as a method for producing alkylene carbonates, which are useful as solvents, raw materials for organic synthesis, and electrolytes for secondary batteries, and as an apparatus used therefor. [Explanation of symbols]

[0074] 1,10: Alkylene carbonate manufacturing apparatus 2: First reaction vessel 3,12: Nozzle 4,16: Carbon Dioxide Supply Department 5:Catalyst supply section 6: Alkylene oxide supply unit 7,14: Circulation circuit 8,13: Heat exchanger 9,15: External pump 11: Second reaction vessel 22: Third reaction vessel

Claims

1. A method for producing alkylene carbonate using a first reaction vessel containing a reaction solution containing a catalyst and gaseous carbon dioxide, Step (A) involves supplying a raw material solution containing alkylene oxide through a nozzle so that it moves from the top of the first reaction vessel along its inner surface to the bottom of the first reaction vessel, and supplying the raw material solution containing dissolved carbon dioxide from the first reaction vessel to the reaction solution. Step (B) of reacting alkylene oxide with carbon dioxide in a reaction solution containing the catalyst at the bottom of the first reaction vessel to obtain alkylene carbonate, Includes, The ratio (DL / DT) of the height DL from the liquid level in the first reaction vessel to the nozzle outlet to the height DT from the bottom tangent line of the first reaction vessel to the nozzle outlet is 0.1 to 0.

7. The reaction solution containing the catalyst is supplied from the top of the first reaction vessel. The nozzle's nozzle opening is directed toward the wall of the first reaction vessel, and in step (A), the raw material liquid is supplied by the nozzle by being sprayed toward the wall of the first reaction vessel. The ratio of the distance between the nozzle nozzle and the wall surface to the inner diameter of the first reaction vessel (nozzle nozzle-to-wall distance / inner diameter of the reaction vessel) is 0.30 or less. The alkylene carbonate is produced at a rate of 1 ton / hour or more. A method for producing alkylene carbonate.

2. A method for producing alkylene carbonate according to claim 1, wherein two or more of the nozzles are used.

3. The reaction liquid contained in the first reaction vessel is withdrawn from the bottom of the first reaction vessel, and a portion of it is supplied into the first reaction vessel as the raw material liquid. The method for producing alkylene carbonate according to claim 1, wherein the number of times the reaction solution is circulated per unit time is 10 to 70 times / hr.

4. The method for producing alkylene carbonate according to claim 1, wherein the operating pressure of the first reaction vessel is 4 to 12 MPa.

5. A method for producing alkylene carbonate according to claim 1, wherein the ratio (DL / DT) is 0.10 to 0.

40.

6. The method for producing alkylene carbonate according to claim 1, wherein the height / inner diameter ratio of the first reaction vessel is 3 to 7 and the inner diameter is 1 to 4 m.

7. A method for producing an alkylene carbonate according to claim 1, wherein the alkylene oxide is ethylene oxide and the alkylene carbonate is ethylene carbonate.

8. A method for producing an alkylene carbonate according to claim 1, comprising step (C) of reacting the reaction solution obtained in step (B) with alkylene oxide and carbon dioxide in a second reaction vessel to obtain an alkylene carbonate.

9. A method for producing an alkylene carbonate according to claim 8, comprising step (D) of further reacting the reaction solution obtained in step (C) with alkylene oxide and carbon dioxide in a third reaction vessel to obtain an alkylene carbonate.

10. A first reaction vessel containing a reaction solution including a catalyst, A nozzle for supplying a raw material liquid containing alkylene oxide so as to move from the upper part of the first reaction vessel to the lower part of the first reaction vessel along the inner surface, An apparatus for producing alkylene carbonate, comprising a carbon dioxide supply unit for introducing carbon dioxide into the first reaction vessel, The operation is controlled so that the ratio (DL / DT) of the height from the liquid level in the reaction vessel to the discharge port of the nozzle (DL / DT) to the height DT from the bottom tangent line of the first reaction vessel to the discharge port of the nozzle is between 0.1 and 0.

7. The reaction solution containing the catalyst is supplied from the top of the first reaction vessel. The nozzle's nozzle opening is oriented toward the wall of the first reaction vessel so that the raw material liquid can be injected and supplied to the wall of the first reaction vessel by the nozzle. The ratio of the distance between the nozzle nozzle and the wall surface to the inner diameter of the first reaction vessel (distance between nozzle nozzle and wall surface / inner diameter of reaction vessel) is 0.30 or less. The alkylene carbonate can be produced at a rate of 1 ton / hour or more. Alkylene carbonate manufacturing equipment.

11. A second reaction vessel containing a reaction solution including a catalyst, A nozzle supplies the reaction liquid from the first reaction vessel as a raw material liquid so that it moves from the top of the second reaction vessel along its inner surface to the bottom of the second reaction vessel, The apparatus for producing alkylene carbonate according to claim 10, further comprising a carbon dioxide supply unit for introducing carbon dioxide into the second reaction vessel.

12. The apparatus for producing alkylene carbonate according to claim 11, further comprising a third reaction vessel into which a reaction solution is introduced from the second reaction vessel and further reacted with alkylene oxide and carbon dioxide.

13. An apparatus for producing alkylene carbonate according to any one of claims 10 to 12, wherein the ratio (DL / DT) is 0.10 to 0.40.

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