Method for producing carbonate ester, and catalytic structure for producing carbonate ester

Abstract

It cannot be said that the reaction rate of a carbonate ester production reaction based on carbon dioxide and a monohydric alcohol has been sufficiently improved by conventional catalysts, and higher reaction efficiency is required. In addition, conventional catalyst-supporting structures used in carbonate ester production reactions cannot be said to have always had sufficiently strong structures.　The above problems have been solved by a method for producing a carbonate ester.　Specifically, the method for producing a carbonate ester comprises a step for making a monohydric alcohol and carbon dioxide react in the presence of a catalyst structure to produce a carbonate ester, wherein the catalyst structure includes a substrate and a catalyst layer formed on at least a portion of the surface of the substrate and containing at least a solid catalyst and a binder, the solid catalyst contains particulate cerium oxide, and the binder contains cerium oxide as a uniform component.

Description

Method for producing carbonate ester and catalyst structure for producing carbonate ester

[0001] The present invention relates to a method for producing a carbonate ester and a catalyst structure for producing a carbonate ester.

[0002] In recent years, interest in global warming has been growing. The Conference of the Parties (COP), which discusses international frameworks for reducing greenhouse gas emissions, has set a goal of suppressing greenhouse gas emissions as soon as possible and rapidly reducing them in accordance with the latest science. The COP21 Paris Agreement requires all countries to strive to formulate and submit long-term low greenhouse gas emission development strategies, and Japan has set a long-term goal of reducing greenhouse gas emissions by 80% by 2050.

[0003] Of all the greenhouse gases emitted artificially, carbon dioxide is estimated to have the greatest impact, and efforts to develop technologies to reduce carbon dioxide emissions are being actively pursued in various areas. As one of the countermeasures, several attempts have been proposed to convert emitted carbon dioxide into useful substances, but converting carbon dioxide into another substance requires a large amount of energy, and the development of an effective catalyst to promote the reaction has been desired. Furthermore, in order to make this technology useful for reducing carbon dioxide emissions, it is necessary to produce useful substances that are in high demand.

[0004] Carbonate esters are extremely useful compounds, being used as additives such as gasoline additives for improving the octane number and diesel fuel additives for reducing particles in exhaust gases, as well as alkylating agents, carbonylating agents, solvents, etc. in synthesizing resins and organic compounds such as polycarbonates, urethanes, pharmaceuticals, and agricultural chemicals, as well as raw materials for electrolytes in lithium batteries, lubricating oil raw materials, and oxygen scavengers for rust prevention in boiler piping.

[0005] Carbonate esters are carbonate CO(OH) ２It is a general term for compounds in which one or both of the two hydrogen atoms in the carbonic acid group are substituted with an alkyl group or an aryl group, and has a structure of RO-C(=O)-OR' (R and R' represent a saturated hydrocarbon group or an unsaturated hydrocarbon group). Therefore, if it were possible to efficiently produce such compounds from carbon dioxide, which is a compound equivalent to carbon dioxide, it could be a useful method for reducing carbon dioxide emissions.

[0006] It is known that the direct synthesis of carbonate esters from carbon dioxide and alcohols proceeds dramatically faster in the presence of a solid catalyst and a nitrile hydrating agent (see, for example, Patent Document 1). There are also known examples of immobilizing a catalyst on a catalyst-supported structure and using it in a solution reaction system (see, for example, Patent Document 2).

[0007] JP 2012-162523 A International Publication No. 2020 / 013135

[0008] Conventional catalysts used in the reaction of producing a carbonate ester from carbon dioxide and a monohydric alcohol have not been able to sufficiently improve the reaction rate, and higher reaction efficiency has been desired. Furthermore, conventional catalyst-supported structures used in the reaction of producing a carbonate ester have not necessarily been able to be said to have a sufficiently strong structure.

[0009]

[0009] In the course of intensive research to solve the above problems, the present inventors have found that the use of a binder having predetermined components together with a catalyst can sufficiently improve the efficiency of the carbonate ester production reaction and also realize a catalyst-supported structure having a strong structure. The present invention includes a method for producing a carbonate ester described below.

[0010] [1] A method for producing a carbonate ester, comprising a step of reacting a monohydric alcohol and carbon dioxide in the presence of a catalyst structure to produce the carbonate ester, wherein the catalyst structure comprises a substrate and a catalyst layer formed on at least a portion of the surface of the substrate and containing at least a solid catalyst and a binder, wherein the solid catalyst contains particulate cerium oxide, and the binder contains cerium oxide as a uniform component. [2] A method for producing a carbonate ester according to [1] above, wherein the cerium oxide contained in the binder is derived from at least one cerium compound selected from the group consisting of cerium acetate, cerium sulfate, and cerium nitrate. [3] A method for producing a carbonate ester according to [2] above, further comprising a binder production step of producing the binder, wherein the cerium compound is calcined to obtain cerium oxide in the binder production step. [4] A method for producing a carbonate ester according to any of [1] to [3] above, wherein the content of the cerium oxide contained as a binder in the catalyst layer is adjusted to be within a predetermined range. [4a] The method for producing a carbonate ester according to [2] or [3] above, for example [2] above, wherein the content of the cerium oxide derived from the cerium compound in the catalytic layer is 1.0 to 10 wt % based on the total weight of the catalytic layer. [4b] Any of [1] to [3] above, for example [1] above, wherein the content of the cerium oxide as a uniform component in the catalytic layer is 1.0 to 10 wt % based on the total weight of the catalytic layer. [5] Any of [1] to [4] above, for example [1] above, wherein the substrate is ceramic. [6] The method for producing a carbonate ester according to [1] above, for example [6] above, wherein the supported mass of the solid catalyst in the catalytic layer is 15 g / m ２ More than 200g / m ２ [7] A method for producing a carbonate ester according to any one of the above [1] to [5], for example, the method for producing a carbonate ester according to the above [1], wherein a hydrating agent is used to remove water generated as a by-product in the reaction for producing the carbonate ester.

[0011] [8] A catalyst structure for producing a carbonate ester, comprising: a substrate; and a catalyst layer formed on at least a part of a surface of the substrate and containing at least a solid catalyst and a binder, wherein the solid catalyst contains particulate cerium oxide, and the binder contains cerium oxide as a uniform component. [9] The catalyst structure for producing a carbonate ester according to [8] above, wherein the content of the cerium oxide as a uniform component in the catalyst layer is 1.0 to 10 wt % based on the total weight of the binder.

[10] The catalyst structure for producing a carbonate ester according to [8] or [9] above, for example, [8] above, wherein the substrate is ceramic.

[11] The catalyst structure for producing a carbonate ester according to [8] above, wherein the supported mass of the solid catalyst in the catalyst layer is 15 g / m ２ More than 200g / m ２

[12] The catalyst structure for producing a carbonate ester according to any one of the above [8] to

[10] , for example, the catalyst structure for producing a carbonate ester according to the above [8], wherein the substrate has a honeycomb structure, and the cell density of the substrate is 15 to 200 (cell / cm ２ [12a] The catalyst structure for producing a carbonate ester according to any one of the above [8] to

[11] , for example, the catalyst structure for producing a carbonate ester according to the above [8], wherein the cell density of the substrate is 15 to 200 (cell / cm ２ ) and the wall thickness of the substrate is 0.01 to 2.0 mm.

[0012] According to the present invention, it is possible to improve the reaction rate of a carbonate ester production reaction and efficiently produce a carbonate ester. Furthermore, the catalyst structure for carbonate ester production of the present invention has a strong structure, and is capable of suppressing powdering and detachment of the catalyst even after long-term use, thereby maintaining excellent catalytic efficiency.

[0013] FIG. 1 is a diagram schematically illustrating a specific example of a carbonate ester production facility including various devices such as a carbonate ester production device having a catalyst structure.

[0014] Preferred embodiments of the present invention will now be described in detail.

[0015] [1. Catalyst structure for producing carbonate ester] First, a preferred embodiment of the catalyst structure for producing carbonate ester of the present invention will be described. The catalyst structure for producing carbonate ester (hereinafter also simply referred to as "catalyst structure") catalyzes the production of a carbonate ester from carbon dioxide and a monohydric alcohol, preferably in the presence of a hydrating agent.

[0016] The catalyst structure for producing a carbonate ester according to this embodiment includes a substrate and a catalyst layer formed on at least a portion of the surface of the substrate and including a solid catalyst and a binder. The solid catalyst in the catalyst layer includes at least particulate cerium oxide. The binder in the catalyst layer includes cerium oxide as a uniform component. In this embodiment, the catalyst structure for producing a carbonate ester includes an intermediate layer made of an inorganic binder between the catalyst layer and the substrate. Each component of the catalyst structure for producing a carbonate ester will be described below.

[0017] (1.1. Substrate) The substrate is a catalyst support structure for supporting a solid catalyst. By supporting the solid catalyst on the surface of the substrate, uneven distribution of the solid catalyst within the reaction vessel during the reaction is suppressed compared to when a powdered catalyst is used as is, and local temperature variations within the reaction vessel due to the generated reaction heat can be reduced. Therefore, according to this embodiment, the product carbonate ester can be produced with high efficiency. Furthermore, even if the activity of the solid catalyst decreases during a long-term reaction, it can be regenerated by heat treatment or the like after removal from the reaction vessel to restore its function, making it easy to continue using it for a long period of time. Furthermore, as will be described in detail below, by adjusting the components of the solid catalyst 40, it is possible to maintain good catalytic function for a long period of time, thereby reducing the frequency of regeneration treatment.

[0018] The substrate is not particularly limited as long as it can form a catalyst layer containing a solid catalyst, and any material, shape, and size can be used. In particular, it is preferable that the substrate has continuous pores that serve as channels for the raw material compounds such as monohydric alcohol and carbon dioxide. The substrate having such continuous pores improves the diffusion efficiency of the raw material monohydric alcohol and carbon dioxide and facilitates the recovery of products such as carbonate ester and by-product water. Furthermore, forming a catalyst layer on the surface of the continuous pores increases the contact area between the catalyst layer and the raw material monohydric alcohol and carbon dioxide, thereby improving the efficiency of the carbonate ester production reaction.

[0019] The shape of the substrate may be, for example, a porous shape such as a foam, a corrugated shape, a honeycomb shape (monolith shape), a mesh shape, a cylindrical shape, a columnar shape, or a cylindrical shape. The substrate is preferably porous, foam, honeycomb, or mesh. These shapes have communicating holes, so the effects of having communicating holes as described above can be suitably obtained. In particular, when the substrate is honeycomb-shaped, the physical strength of the substrate can be improved, the shape stability of the substrate can be improved, and the specific surface area of ​​the communicating holes can be made relatively large.

[0020] The material constituting the substrate is not particularly limited, but is preferably various ceramic materials such as cordierite, mullite, silicon carbide, alumina, silica, titania, zirconia, and ceria, or metal materials such as stainless steel and aluminum steel. These materials may also be combined. Among the above-mentioned substrate materials, ceramic and metal materials are preferred, and therefore the substrate is preferably a ceramic honeycomb or a metal honeycomb, particularly preferably a ceramic honeycomb. Forming the substrate from ceramic can further improve the adhesion of the catalyst layer to the substrate. On the other hand, using a metal, such as stainless steel (martensitic, ferritic, austenitic, austenitic-ferritic two-phase, and precipitation-strengthened steel), as the substrate material can improve the thermal conductivity of the substrate.

[0021] When a substrate having cells such as a honeycomb structure is used, the thickness of the cell walls is, for example, 0.01 to 2.0 mm (approximately 0.4 to 80 mil), preferably 0.1 to 1.5 mm (approximately 4 to 60 mil), and more preferably 0.5 to 1.3 mm (approximately 2 to 50 mil). Note that the ranges described here are for the thickness of the cell walls of the substrate, and for the thickness of the cell walls of a catalyst support structure in which a catalyst layer is laminated on the surface of the substrate, it is preferable that the range has limit values ​​obtained by adding the thickness of the catalyst layer, which will be described later, to the upper and lower limits of the above ranges.

[0022] In addition to the above-mentioned material, shape, and cell wall thickness, factors that determine the structure of a substrate having cells also include cell density. Cell density is expressed as the number of cells per unit area of ​​a cross section perpendicular to the axis of the honeycomb structure. The cell density of a honeycomb substrate is preferably 15 to 200 cells / cm. ２ (approximately 200 to 1300 cells / inch ２ ), and more preferably 20 to 150 cells / cm ２ (approximately 130 to 970 cells / inch ２ ), and more preferably 25 to 120 cells / cm ２ (approximately 160 to 770 cells / inch ２ ) or 30 to 100 cells / cm ２ (approximately 193 to 645 cells / inch ２ ), and particularly preferably 45 to 93 cells / cm ２ (approximately 290 to 600 cells / inch ２ ) or 62 to 93 cells / cm ２ (approximately 400 to 600 cells / inch ２ )

[0023] (1.2. Catalyst Layer) The catalyst layer is formed on at least a portion of the surface of the substrate. The catalyst layer has a solid catalyst containing at least particulate cerium oxide, and catalyzes the reaction of carbon dioxide and a monohydric alcohol to produce a carbonate ester. Such a catalyst layer is preferably formed on the inner wall surfaces of the communicating pores of the substrate. More preferably, the catalyst layer covers all surfaces that may come into contact with the raw material substrates of the carbonate ester production reaction, such as carbon dioxide and a monohydric alcohol, such as the inner wall surfaces of the communicating pores.

[0024] The catalyst layer contains at least a solid catalyst and a binder. Cerium oxide, an essential component of the solid catalyst, has excellent catalytic activity in the reaction of carbon dioxide and a monohydric alcohol to produce a carbonate ester. Generally, cerium oxide tends to powder easily. However, in this embodiment, cerium oxide is firmly fixed to the substrate by the binder described below, which inhibits detachment and prevents powdering.

[0025] The catalyst may contain one or more catalysts other than cerium oxide. Such catalysts may be any catalyst that catalyzes the reaction between carbon dioxide and a monohydric alcohol, and examples thereof include tin compounds, thallium compounds, nickel compounds, vanadium compounds, copper compounds, alkali carbonates, zirconium oxide, titanium oxide, and rare earth elements other than cerium (particularly their oxides). Among these, zirconium oxide is preferred due to its high catalytic activity. In this case, the proportion of cerium oxide in the solid catalyst is, for example, 5 atomic % or more, preferably 20 atomic % or more. Furthermore, the proportion of cerium oxide in the solid catalyst may be 100 atomic %.

[0026] When a cerium oxide catalyst is continuously used in the direct synthesis reaction of carbonate ester, its catalytic activity decreases over time, and the catalyst may need to be regenerated relatively frequently. However, high catalytic activity can be maintained by adjusting the catalyst components. For example, when a rare earth element other than cerium is added as a promoter component, the catalytic activity of the solid catalyst tends to be maintained at a high level for a long period of time in the reaction of producing carbonate ester.

[0027] Rare earth elements other than cerium include scandium, yttrium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Of these rare earth elements, lanthanum, praseodymium, and gadolinium are preferably added to the solid catalyst, and lanthanum is particularly preferred. These metal elements are contained in the solid catalyst or present in the surface layer of the solid catalyst mainly as oxides.

[0028] The proportion of the promoter component in the solid catalyst, for example, an oxide of a rare earth element, is preferably 0.01 to 10 mass %, more preferably 0.05 to 5.0 mass %, even more preferably 0.1 to 2.5 mass %, and particularly preferably 0.2 to 2.0 mass %, for example, 1 mass %, based on the total mass of the solid catalyst.

[0029] The amount of the solid catalyst carried in the catalyst layer is 15 g / m based on the unit area of ​​the catalyst layer. ２ More than 200g / m ２ It is preferable that the weight is 20 g / m or less. ２ 150g / m or more ２ More preferably, it is 25 g / m or less. ２ More than 100g / m ２ Less than or equal to 25 g / m ２ 80g / m or more ２ In a catalyst structure containing such a solid catalyst, the reaction efficiency of the catalytic reaction can be improved. ２ If the amount of the supported solid catalyst is less than 200 g / m, the reaction efficiency of the catalytic reaction by the catalyst structure may be insufficient. ２ If the temperature is higher than 1000 K, the diffusion of the raw material substrate into the depth of the catalyst layer may be hindered, and the reaction efficiency may be reduced.

[0030] Thus, the amount of the solid catalyst supported and the reaction efficiency do not simply have a positive correlation, and there may be an appropriate range of the amount of the solid catalyst supported to achieve high reaction efficiency. A catalyst structure supporting a solid catalyst with a content within the above range can maintain high reactivity even at a high raw material supply rate, and further, the reactor can be made relatively small. The cost of a plant including such a catalyst structure can be kept low.

[0031] From the viewpoint of the reaction efficiency of the catalytic reaction by the catalyst structure, the amount of the solid catalyst carried in the catalyst layer is, for example, 10 g / m ２ More than 200g / m ２ Preferably 15 g / m or less ２ 150g / m or more ２ or less, more preferably 15 g / m ２ 70g / m or more ２ More preferably 15 g / m or less ２ 30g / m or more ２ Similarly, from the viewpoint of the reaction efficiency of the catalytic reaction by the catalyst structure, the amount of cerium oxide carried in the catalyst layer is, for example, 10 g / m ２ More than 200g / m ２ Below, 15g / m ２ More than 200g / m ２ and preferably 15 g / m ２ 150g / m or more ２ or less, more preferably 15 g / m ２ 70g / m or more ２ More preferably 15 g / m or less ２ 30g / m or more ２ The following is the result.

[0032] The thickness of the catalyst layer is, for example, 12 μm to 150 μm. While the thickness of the catalyst layer in conventional products is generally about 5 μm or less, the catalyst layer included in the catalyst structure of this embodiment can be said to be significantly thicker. Conventionally, it has been difficult to support such a large amount of solid catalyst without inhibiting its reaction activity, but in this embodiment, this problem is solved mainly by the binder described below. The average thickness of the catalyst layer may be about 12 μm to 180 μm, preferably about 15 μm to 150 μm, and more preferably about 30 μm to 100 μm.

[0033] Furthermore, the thickness of the catalyst layer formed in the through-holes of the substrate is usually not necessarily uniform due to the shape of the through-holes. However, by forming a uniform catalyst layer on a plate-shaped substrate by a doctor blade method or the like and obtaining a correlation between the amount of solid catalyst in the catalyst layer and the thickness, it is possible to determine the average apparent thickness of the catalyst layer on the substrate based on the weight of the supported solid catalyst, even when through-holes are formed.

[0034] The average particle size of the particulate catalyst is not particularly limited, but is, for example, 0.001 μm to 100 μm, preferably 0.005 μm to 100 μm, more preferably 0.01 μm to 80 μm, even more preferably 0.1 μm to 60 μm, particularly preferably 1.0 μm to 30 μm, and even more preferably 3.0 μm to 15 μm. This makes it possible to increase the specific surface area of ​​the catalyst, thereby improving the efficiency of the catalytic reaction and preventing the catalyst from separating from the binder.

[0035] In this specification, the term "average particle size" refers to the volume-based 50% particle size (D50) measured by a wet laser diffraction / scattering method. When measurement by the laser diffraction / scattering method is difficult due to poor dispersibility or other reasons, methods such as calculation from scanning electron microscope observation or X-ray diffraction measurement, or image imaging methods can be applied.

[0036] The catalyst layer contains the above-described solid catalyst and a binder for fixing the solid catalyst. The binder contains at least cerium oxide. The cerium oxide contained in the binder does not inhibit the activity of the particulate catalyst, and can improve the efficiency of the carbonate ester production reaction. Furthermore, a catalyst layer using a binder containing cerium oxide, which is the same as the catalyst, as a main component, can suppress side reactions that may occur during the carbonate ester production reaction.

[0037] A catalyst layer containing a binder can support a relatively large amount of catalyst. Furthermore, the binder can firmly fix the solid catalyst containing cerium oxide to the substrate, thereby preventing the solid catalyst from separating or peeling off during the reaction. A catalyst structure having a catalyst layer containing such a binder can be used for a long period of time while maintaining high activity. Furthermore, the use of an inorganic binder can prevent the catalyst layer from deteriorating, even when the reaction temperature or regeneration treatment temperature becomes relatively high, and can maintain high adhesion between the catalyst layer and the substrate.

[0038] The binder may contain components other than cerium oxide, such as silica. The type of silica is not particularly limited, and it may be silica formed using any compound as a precursor. Furthermore, these silicas may be amorphous or crystalline. Furthermore, the binder may contain small amounts of alumina, magnesium, calcium, impurity components that may be mixed in during the binder manufacturing process, and the like. Thus, the binder preferably does not contain organic compounds, and may be referred to as an inorganic binder.

[0039] The proportion of cerium oxide contained in the binder is preferably 1.0 to 10 mass %, more preferably 2.0 to 8.0 mass %, or 3.0 to 7.0 mass %, and even more preferably 3.0 to 5.0 mass %, based on the total weight of the catalyst layer. If the amount of cerium oxide contained as a binder in the catalyst layer is too large, pressure loss may increase, while if it is too small, the binding ability may be insufficient.

[0040] The proportion of cerium oxide in the binder based on the total weight of the binder is preferably 20% by mass or more, or 30% by mass or more, more preferably 50% by mass or more, or 70% by mass or more, and even more preferably 80% by mass or more, or 90% by mass or more. The binder more preferably consists essentially of cerium oxide, and particularly preferably consists solely of cerium oxide.

[0041] Unlike the cerium oxide in the catalyst particles, the cerium oxide in the binder exists as a uniform component in the binder, with no visible particles. That is, the cerium oxide as a uniform component in the binder does not exist as fine particles, and exists in the binder in a state in which it is confirmed that the cerium oxide does not exist as particles even when observed under magnification. This is evident, for example, from the fact that in the mixed solution of binder raw materials used in the process of producing the binder, which will be described in detail later, cerium acetate is completely dissolved in water or the like to form a uniform component.

[0042] The specific surface area of ​​the particles of the solid component in the binder is not particularly limited, but may be, for example, 1 m ２ / g or more 1000m ２ / g or less, preferably 10m ２ / g or more 500m ２ / g or less. When the specific surface area of ​​the binder is in the above range, the diffusion rate of carbon dioxide and monohydric alcohol in the binder is sufficient, the reaction on the surface of the solid catalyst can be promoted, and the solid catalyst can be more firmly fixed to the catalyst layer. The specific surface area can be measured by the BET method.

[0043] The amount of the solid component carried in the binder in the catalyst layer is, for example, 1 g / m ２ More than 100g / m ２ Less than 1 g / m, more preferably ２ 40g / m or more ２ This makes it possible to increase the exposed area of ​​the solid catalyst to improve the reaction efficiency, and also to firmly fix the solid catalyst to the substrate.

[0044] In the catalyst layer, the solid component in the binder is contained in a proportion of, for example, 0.01 g to 5 g, preferably 0.10 g to 1.0 g, per 1 g of solid catalyst, which increases the exposed area of ​​the solid catalyst, improving reaction efficiency, and also firmly fixing the solid catalyst to the substrate.

[0045] The solid components in the binder refer to inorganic oxide particles or solidified binder particles intentionally introduced into the binder. The mass proportion of the solid components in the inorganic binder can be determined by dividing the mass of the residue after drying and curing the inorganic binder alone by the mass of the inorganic binder before drying and curing. Therefore, the mass of the solid components in the inorganic binder can be calculated by multiplying the mass proportion of the solid components by the applied mass of the inorganic binder.

[0046] (1.3. Intermediate Layer) An intermediate layer may be provided between the substrate and the catalyst layer. The intermediate layer may contain, for example, a component forming the binder described above, such as cerium oxide. By providing an intermediate layer primarily composed of an inorganic binder or consisting of an inorganic binder between the catalyst layer containing the solid catalyst and the substrate, the adhesion of the catalyst layer to the substrate is further improved, preventing the solid catalyst from separating from the catalyst structure. Furthermore, by providing such an intermediate layer, sufficient adhesion between the catalyst layer and the substrate can be achieved even when a substrate made of a material that would normally have low adhesion to the catalyst layer, such as a metal substrate, is used. However, the intermediate layer may not be provided in order to reliably prevent increased pressure loss, side reactions that may occur due to components other than the catalyst, and the generation of unintended by-products. Furthermore, the binder contained in the catalyst layer and the binder forming the intermediate layer may be different in composition or may be the same.

[0047] In the intermediate layer, the amount of the solid component carried in the binder is, for example, 1 g / m ２ More than 100g / m ２ or less, more preferably 10 g / m ２ 50g / m or more ２ Within the above range, it is possible to prevent cohesive failure of the intermediate layer and further improve the adhesion between the catalyst layer and the substrate.

[0048] In the catalyst structure for producing a carbonate ester according to the present embodiment described above, a relatively large amount of solid catalyst is firmly fixed in the catalyst layer by a binder containing cerium oxide. The binder does not inhibit the catalytic reaction caused by the solid catalyst. When a carbonate ester is produced using such a catalyst structure for producing a carbonate ester, the efficiency of the reaction for producing the carbonate ester is excellent. Furthermore, since the solid catalyst is firmly fixed to the substrate by an inorganic binder or the like, it is prevented from being separated from the catalyst structure for producing a carbonate ester, and powdering of the solid catalyst is also prevented.

[0049] Such a catalyst structure for producing carbonate esters can achieve high reaction efficiency even in reactions under high liquid flow rates required in industrial processes. Furthermore, because the solid catalyst is prevented from separating and becoming powdery, it can be used repeatedly and has excellent durability even in the harsh environments required in industrial processes.

[0050] Although the catalyst structure for producing a carbonate ester according to this embodiment has been described above, the present invention is not limited to the above embodiment. For example, a catalyst structure for producing a carbonate ester different from the above embodiment may have a catalyst layer on a substrate, and may omit the intermediate layer containing a binder as a main component. In this way, even when the intermediate layer is omitted, the solid catalyst in the catalyst layer is sufficiently fixed by the binder containing cerium oxide or the like, and separation from the catalyst structure for producing a carbonate ester and the resulting powdering are prevented.

[0051] The boundary between the catalyst layer and the intermediate layer can be observed by elemental analysis using an optical microscope, a scanning electron microscope, or an EDS (energy dispersive X-ray spectroscope). The amount of solid catalyst supported in the catalyst layer can be calculated based on the area of ​​the catalyst layer and the overall supported mass of the catalyst layer by identifying the proportion of a metal component (e.g., cerium) in the catalyst layer by elemental analysis. Specifically, when the solid catalyst component is cerium oxide, the amount can be calculated using the following formula (I): (Solid catalyst supported amount) = [(mass of catalyst layer) × (mass proportion of cerium in catalyst layer) × ((mass of cerium oxide) / (mass of cerium))] / (area of ​​catalyst layer) (I). This value is synonymous with the mass of the solid catalyst per unit area of ​​the substrate where the solid catalyst is present, and can be calculated regardless of the presence or absence of an intermediate layer.

[0052] Scanning inductively coupled plasma (ICP) can be used as an elemental analysis method to identify metal components. The amount of binder supported in the catalyst layer and intermediate layer can be calculated in the same way by calculating the solid component ratio in the binder used to form the catalyst layer or intermediate layer from the metal component ratio determined by the elemental analysis described above. Here, the catalyst layer area refers to the area of ​​the portion on which the solid catalyst (catalyst layer) is applied (formed). For example, when the substrate has a honeycomb shape and the outer periphery is not coated with a catalyst layer, it refers to the surface area of ​​the entire substrate on which the catalyst layer is applied, forming the internal interconnecting pores. Here, even when an intermediate layer is present, the amount of solid catalyst supported can be calculated using the same concept.

[0053] [2. Method for Producing Catalyst Structure for Carbonate Ester Production] Next, a method for producing the catalyst structure for carbonate ester production according to this embodiment will be described.

[0054] First, a mixture for forming a catalyst layer is prepared for forming a substrate and a catalyst layer by dissolving or dispersing a solid catalyst, a precursor of cerium oxide as a binder material, and the like in an appropriate liquid medium, such as water or alcohol.

[0055] Next, a catalyst layer is formed on the surface of the substrate. Specifically, as described below, a catalyst layer-forming mixture is applied to the surface of the substrate, and then dried and cured to form a catalyst layer. The catalyst layer-forming mixture can be applied by any method, such as coating using a bar coater, doctor blade, roll coater, comma coater, die coating, gravure coating, spin coating, slit coating, inkjet, spraying, or immersion. In particular, when the substrate has through-holes, immersion is preferred, specifically, immersing the substrate in the catalyst layer-forming mixture. Note that the catalyst layer-forming mixture may be applied multiple times to increase the film thickness of the catalyst layer.

[0056] When the substrate is a metal, or when insufficient adhesion between the substrate and the catalyst layer is expected, it is preferable to perform the following pretreatment step before forming the catalyst layer. In the pretreatment step, for example, the substrate is washed with a volatile organic solvent such as alcohol or acetone to remove oil from the substrate surface, and then dried. The substrate is then immersed in an alkaline aqueous solution, washed with water, and dried. The substrate is then immersed in an acidic aqueous solution, washed with water, and dried. Alternatively, the surface of the substrate may be subjected to chemical treatment, heat treatment, plasma treatment, UV treatment, or corona treatment.

[0057] The drying temperature for the mixed liquid for forming a catalyst layer applied to the surface of the substrate may be any temperature at which the liquid medium can be removed, and may be set appropriately depending on the boiling point of the medium, for example, from 60° C. to 200° C., preferably from 70° C. to 160° C., and more preferably from 80° C. to 120° C. The drying time may also be adjusted appropriately depending on the desired drying state, etc.

[0058] The type of cerium oxide precursor contained in the catalyst layer-forming mixed solution is not particularly limited as long as it is a raw material that becomes cerium oxide after the calcination step described below. Specific examples of cerium oxide precursors include the following compounds: halides such as cerium chloride; inorganic salts such as cerous nitrate (cerium nitrate) and cerium sulfate; carboxylates such as cerium acetate and cerium(III) 2-ethylhexanoate; cerium hydroxide; and complex compounds in which cerium is coordinated with a ligand such as acetylacetone or an alkoxide (methoxide, ethoxide, tert-butoxide, etc.) (e.g., cerium(III) triacetylacetonate). Among these cerium oxide precursors, cerium sulfate, cerium nitrate, and cerium acetate are preferred, with cerium acetate being particularly preferred, from the viewpoint of their excellent adhesive properties that fix the catalyst particles as a binder after calcination. In this way, by using a binder derived from a cerium oxide precursor such as cerium acetate, side reactions caused by components different from the solid catalyst, such as alumina, can be suppressed, and the main reaction can be made sufficiently efficient.

[0059] To produce cerium oxide from the above-described catalyst layer-forming mixed solution, the mixed solution is calcined after application to the substrate. That is, the step of generating the binder contained in the catalyst layer involves calcining the cerium oxide precursor contained in the mixed solution. The temperature of the calcination step for hardening the catalyst layer, including the binder, can be appropriately set depending on the components of the mixed solution, and is, for example, 200°C to 900°C, preferably 300°C to 800°C, more preferably 400°C to 700°C or 450°C to 750°C, and even more preferably 500°C to 700°C or 550°C to 750°C. The calcination time can also be adjusted appropriately, but is, for example, 10 minutes to 10 hours, preferably 30 minutes to 7 hours, and more preferably 1 hour to 5 hours. The mixed solution applied to the substrate may be dried before calcining in the calcination step. Drying is carried out, for example, by blowing air, and the drying temperature is, for example, from 40° C. to 200° C., preferably from 50° C. to 150° C., more preferably from 60° C. to 120° C. or from 65° C. to 130° C. The drying temperature is further preferably from 70° C. to 110° C. or from 80° C. to 120° C. The drying time of the mixed liquid can also be adjusted appropriately, but is, for example, from 1 minute to 30 minutes, preferably from 3 minutes to 20 minutes, more preferably from 5 minutes to 15 minutes.

[0060] The reaction of forming cerium oxide from a precursor, for example cerium acetate, by calcination is believed to proceed according to the following general formula (II): ３ COO) ３ → High humidity type Ce (CH ３ COO) ３ → Ce ８ ・O ３ (CH ３ COO) １８ → CeOCH ３ COO → Ce ２ O ２ CO ３ → CeO ２...(II) Thus, cerium oxide is produced by thermal decomposition of the precursor during calcination, which is the main process in the binder production process. In the binder obtained by the calcination process, unlike cerium oxide as a particulate catalyst, cerium oxide does not have a definite shape and exists as a uniform component in the binder. This uniform component of cerium oxide is contained in the binder so as to fill the gaps between the cerium particles of the catalyst.

[0061] When an intermediate layer is provided on the catalyst structure, for example, the following step may be further required. In addition to the above-mentioned substrate and catalyst layer-forming mixed liquid, a binder stock solution for forming the intermediate layer is prepared. The binder stock solution is obtained by dissolving or dispersing a binder material, such as a cerium oxide precursor, in an appropriate liquid medium, such as water or alcohol. The concentration of the binder material in the binder stock solution is not particularly limited and can be set appropriately depending on the method for applying the binder stock solution to the substrate.

[0062] Then, before forming the catalyst layer, an intermediate layer is formed on the substrate. Specifically, the intermediate layer is obtained by applying the above-mentioned binder concentrate solution to the substrate, followed by drying and curing. The binder concentrate solution can be applied by any method, such as coating using a bar coater, doctor blade, roll coater, comma coater, die coating, gravure coating, spin coating, slit coating, inkjet, spraying, immersion, etc. In particular, when the substrate has through holes, immersion is preferred, specifically immersing the substrate in the binder concentrate solution. Note that the application of the binder solution may be repeated multiple times to increase the film thickness of the intermediate layer.

[0063] Next, the binder concentrate solution applied to the substrate is dried and cured to form an intermediate layer. The drying conditions can be the same as the drying conditions for the mixed solution for forming the catalyst layer on the substrate described above. Note that when a metal is used as the substrate, if it is expected that the adhesion between the substrate and the intermediate layer is insufficient, a pretreatment process similar to the pretreatment process performed prior to the formation of the catalyst layer described above may be performed before forming the intermediate layer.

[0064] [3. Method for Producing Carbonate Ester] Next, a method for producing a carbonate ester will be described based on a preferred embodiment. The method for producing a carbonate ester according to this embodiment includes a step of reacting a monohydric alcohol with carbon dioxide in the presence of the above-described catalyst structure to produce a carbonate ester.

[0065] Prior to describing the method for producing a carbonate ester according to this embodiment, the mechanism of the reaction occurring in this method will be described. First, the catalyst layer included in the catalyst structure catalyzes the reaction of a monohydric alcohol represented by the following formula (1) with carbon dioxide: 2ROH + CO ２ ⇔ (RO) ２ CO + H ２ O... (1)

[0066] Here, the catalytic mechanism of the solid catalyst of the catalyst structure is that alcohol is dissociated and adsorbed on the basic points in the form of R-O-M (M is the solid catalyst), and CO ２ On the other hand, alcohol is adsorbed on the acidic sites in the form of HO-R...M, and RO-C(=O)-OR is generated between the two adsorbed species.

[0067] The reaction represented by the above formula (1) is a reversible reaction. Therefore, if by-product water is present, it will react again with the produced carbonate ester to return to monohydric alcohol and carbon dioxide. Therefore, in order to remove the by-product water, it is preferable to carry out the hydration reaction represented by the following formula (2) using a hydrating agent. H ２ O + R'CN ⇒ R'C(=O)-NH ２ ...(2) As the wettable powder, a cyano group-containing compound represented by the above formula (2) is used, as will be described later.

[0068] As a result of the removal of water by the reaction represented by the above formula (2), the reverse reaction in formula (1) is suppressed and the reaction for producing a carbonate ester is promoted. Although the reason is not clear, it is thought that the solid catalyst also has catalytic activity for the hydration reaction represented by the above formula (2). The mechanism of the reaction occurring in this method has been explained above.

[0069] As described above, the method for producing a carbonate ester according to this embodiment includes a step of producing a carbonate ester by reacting a monohydric alcohol with carbon dioxide in the presence of the catalyst structure and a hydrating agent. Specifically, the catalyst structure is placed in a reaction vessel, and the hydrating agent, the monohydric alcohol, and carbon dioxide are introduced into the reaction vessel, whereby the reaction of the carbonate ester is carried out.

[0070] The monohydric alcohol can be one or more compounds selected from primary alcohols, secondary alcohols, and tertiary alcohols. Specific examples of the monohydric alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-pentyl alcohol, n-hexanol, 2-hexanol, 3-hexanol, heptanol, hexanol, and phenol. The type of monohydric alcohol can be appropriately selected depending on the chemical structure of the desired carbonate ester and the method of use of the resulting carbonate ester.

[0071] The optional hydrating agent is not particularly limited as long as it can react with water to remove water. Examples include cyano group-containing compounds as shown in formula (2) above, which can be used alone or in combination of two or more. Specific examples include acetonitrile, cyanoethane, 1-cyanopropane, 2-cyanopropane, cyanoethylene, phenylacetonitrile, benzonitrile, 2-cyanopyridine, 2-cyanopyrazine, 2-cyanopyrimidine, thiophene-2-carbonitrile, and 2-fluoronitrile (2-cyanofuran). In particular, 2-cyanopyridine is preferred from the standpoint of water removal efficiency, i.e., hydration reaction rate. The amount of hydrating agent used can be determined depending on the amount of monohydric alcohol used. For example, the amount of hydrating agent used is 0.01 to 2 moles, preferably 0.1 to 0.5 moles, per mole of monohydric alcohol used.

[0072] The temperature of the carbonate ester production reaction is not particularly limited, but is preferably 50°C or higher and 300°C or lower. If the reaction temperature is lower than 50°C, depending on the type of reaction substrate, the reaction rate may be low, and both the carbonate ester synthesis reaction and the hydration reaction with the hydrating agent may hardly proceed, resulting in low carbonate ester productivity. If the reaction temperature exceeds 300°C, the reaction rate of each reaction may increase, but depending on the type of reaction substrate, the carbonate ester or the amide monomer obtained by the hydration reaction may be prone to denaturation to other monomers or polymerization, resulting in a low carbonate ester yield. The reaction temperature is more preferably 100°C or higher and 200°C or lower. However, since this reaction temperature is likely to vary depending on the type and amount of solid catalyst and the amount and ratio of raw materials (monohydric alcohol, hydrating agent), it is desirable to appropriately set optimal conditions.

[0073] The reaction pressure is not particularly limited, but is preferably 0.1 MPa or more and 20 MPa or less (absolute pressure). If the reaction pressure is less than 0.1 MPa (absolute pressure), a pressure reducing device is required, which not only makes the equipment complicated and costly, but also requires power energy to reduce the pressure, which tends to reduce energy efficiency. Furthermore, if the reaction pressure exceeds 20 MPa, depending on the type of hydrating agent, the hydration reaction by the hydrating agent may not proceed easily, resulting in a poor yield of carbonate ester, and the power energy required to increase the pressure may be required, which may reduce energy efficiency. Furthermore, from the viewpoint of increasing the yield of carbonate ester, the reaction pressure is more preferably 0.1 MPa or more and 10 MPa or less (absolute pressure).

[0074] The reaction time is not particularly limited and can be set appropriately depending on the type of reaction substrate (raw material), the type of hydrate, and the rate of by-product production, but is, for example, 5 minutes to 24 hours, preferably 15 minutes to 8 hours, and more preferably 30 minutes to 6 hours. When a continuous reaction apparatus is used, the reaction time (residence time) can be determined as the total time from when the raw material is introduced into the reaction vessel to when it is discharged from the reaction vessel, taking into account the flow rate of the raw material. Furthermore, when the reaction is carried out by circulating the reaction substrate through the catalyst structure, the circulation flow rate is defined by the space velocity represented by the following formula (3): Space velocity (per minute) = Circulation flow rate (m ３ / min) ÷ volume of catalyst structure (m ３ ) ... (3)

[0075] The value of the space velocity is not particularly limited, but is, for example, 0.005 to 5000 per minute, preferably 0.05 to 500 per minute, and more preferably 0.5 to 50 per minute. If the space velocity is too low, CO ２ Since the reactant is consumed before passing through the catalyst structure, the reaction efficiency may decrease and side reactions may increase. On the other hand, a higher space velocity requires a larger pump size, which may result in a decrease in energy efficiency. Carbonate esters can be efficiently produced by a step of circulating the reaction substrates including the raw materials through the carbonate ester production apparatus at a space velocity (per minute) in the above-mentioned range, for example, from 0.005 to 5,000.

[0076] As a result, carbonate esters can be produced efficiently. Furthermore, in this embodiment, the catalyst structure according to the embodiment described above is used, and therefore, the solid catalyst is prevented from being separated from the catalyst structure and from being powdered. Therefore, the catalyst structure can be used repeatedly even in the harsh environments required in industrial processes. Furthermore, by adjusting the catalyst components, the activity of the solid catalyst can be maintained better for a long period of time.

[0077] [4. Apparatus for Producing Carbonate Ester] Next, an apparatus for producing a carbonate ester will be described based on a preferred embodiment. The apparatus for producing a carbonate ester includes the above-mentioned catalyst structure for producing a carbonate ester. For example, the apparatus for producing a carbonate ester has a housing (casing). The housing is formed, for example, of a stainless steel pipe or the like, and the catalyst structure for producing a carbonate ester is housed inside the casing. The apparatus for producing a carbonate ester preferably has a plurality of catalyst structures for producing a carbonate ester, and these catalyst structures for producing a carbonate ester are arranged, for example, in series.

[0078] The apparatus for producing a carbonate ester preferably includes a supply path that can supply the monohydric alcohol and carbon dioxide, which are raw materials for producing a carbonate ester, to the catalyst structure for producing a carbonate ester. When the raw materials are supplied to the apparatus for producing a carbonate ester through such a supply path, a carbonate ester production reaction proceeds inside the catalyst structure for producing a carbonate ester. Then, the carbonate ester produced by the carbonate ester production reaction is preferably discharged to the outside of the apparatus for producing a carbonate ester via the discharge path together with unreacted raw materials, etc.

[0079] In order to adjust the temperature of the carbonate ester production reaction, a heat transfer fluid is preferably supplied to the carbonate ester production apparatus. The heat transfer fluid enables the temperature of the catalyst structure for carbonate ester production and the reaction temperature to be adjusted. For this reason, the carbonate ester production apparatus is preferably provided with a heat transfer fluid supply pipe for supplying the heat transfer fluid, and the heat transfer fluid supplied to the carbonate ester production apparatus from the inlet of the heat transfer fluid supply pipe is discharged to the outside of the carbonate ester production apparatus, for example, through an outlet. Thereafter, the heat transfer fluid is adjusted to, for example, a predetermined temperature and then supplied again to the carbonate ester production apparatus through the inlet of the heat transfer fluid supply pipe.

[0080] The configuration of the apparatus for producing carbonate esters is not limited to the above. For example, in order to increase the flow rate of the fluid containing the raw material supplied through the supply channel, the apparatus for producing carbonate esters may be designed to have a shape suitable for larger sizes. When the size of the apparatus for producing carbonate esters is increased, an integrated structure obtained by integrating catalyst structures for producing carbonate esters arranged in parallel may be arranged in series in the height direction. In an apparatus for producing carbonate esters having such a structure, it is easy to replace only the integrated structure in which the catalyst structure considered to have deteriorated is arranged after a long period of operation, thereby minimizing the operating costs of the apparatus for catalysts. The integrated structure obtained by integrating catalyst structures for producing carbonate esters arranged in parallel is preferably provided with a sealing structure to ensure that the fluid always passes through the catalyst structure. Furthermore, in order to ensure uniformity of the fluid flow within the apparatus for producing carbonate esters, it is preferable to provide a space between each stage when integrating structures obtained by integrating catalyst structures for producing carbonate esters arranged in parallel in the height direction. To minimize the size of the apparatus for producing carbonate esters by densely arranging the catalyst structures in the cross section of the apparatus for producing carbonate esters, for example, a rectangular parallelepiped catalyst structure may be used. In this way, when a rectangular parallelepiped catalyst structure is used, a plurality of catalyst structures can be densely packed in the cross section of the carbonate ester production apparatus, thereby minimizing loss of storage space. However, the shape of the catalyst structure is not particularly limited, and the catalyst structure may be a shape other than a rectangular parallelepiped. Furthermore, the catalyst structure preferably has a porous, foam, honeycomb, or mesh structure.

[0081] The integrated structure preferably includes a fixing plate that is part of the housing and that supports a plurality of catalyst structures. Such a fixing plate is formed, for example, with a frame that corresponds to the outer shape of the catalyst structure. The catalyst structure is preferably fitted into the frame and detachably fixed. Alternatively, instead of such a catalyst structure, a rectangular honeycomb structure that does not support a catalyst may be added to the integrated structure. Such a rectangular honeycomb structure that does not support a catalyst can be employed to prevent the total amount of catalyst contained in the carbonate ester production apparatus from becoming excessive. By disposing a small number of structures, such as one or two, that do not support a catalyst in an integrated structure that includes several tens of catalyst structures, for example, about 30 to 40 catalyst structures, the catalyst distribution amount can be adjusted to an appropriate level, thereby suppressing the amount of by-products produced.

[0082] As described above, in the apparatus for producing carbonate esters having a structure in which the catalyst structures are arranged not only in series but also in parallel, that is, a structure in which a plurality of integrated structures in which a plurality of catalyst structures are arranged in parallel are arranged in series, the flow rate of the fluid containing the raw material is, for example, 500 m ３ / h or more, preferably 550 m ３ / h or more. When a fluid is supplied at a flow rate lower than these values, for example, an apparatus for producing a carbonate ester in which only 10 or less catalyst structures are arranged in series is used.

[0083] [5. Carbonate Ester Production Facility] Next, a carbonate ester production facility including the above-described carbonate ester production apparatus, etc. will be described based on a preferred embodiment. As illustrated in Fig. 1 , the carbonate ester production facility 100 includes, for example, a carbonate ester production apparatus 60, a raw material supply system that supplies raw materials to the carbonate ester production apparatus 60, and a recovery system that recovers the produced carbonate ester.

[0084] CO as a raw material supply system ２ The internal pressure of the storage facility 72 is ２ When the pressure is increased by the boost pump 73, ２Carbon dioxide in the storage facility 72 is supplied to the buffer tank 74. Meanwhile, liquid monohydric alcohol and a hydrating agent such as 2-cyanopyridine, which are raw materials stored in a raw material tank 76, are supplied from the raw material tank 76 to the buffer tank 74 by a raw material supply pump 78. In this way, the carbon dioxide and monohydric alcohol, etc., supplied to the buffer tank 74 via separate systems, are mixed in the buffer tank 74. The mixed liquid is supplied to the carbonate ester production apparatus 60 via a first filter 80.

[0085] In the carbonate ester production apparatus 60, a catalyst structure for carbonate ester production (not shown) promotes the carbonate ester production reaction, producing a carbonate ester according to the type of monohydric alcohol used as the raw material. The carbonate ester thus produced is supplied to a recovery system via a second filter 82. In the recovery system, a liquid containing the carbonate ester is separated from a liquid containing the unreacted monohydric alcohol (the raw material) and a hydrating agent such as 2-cyanopyridine. Then, by the action of a reaction liquid circulation pump 84, the liquid containing the carbonate ester is sent to a liquid drainage pump 86, and the liquid containing the monohydric alcohol and the like is returned to the buffer tank 74. In the liquid drainage pump 86, liquids other than the carbonate ester are removed, producing a highly pure carbonate ester.

[0086] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0087] <Production Example 1: Production Example of Cerium Oxide Catalyst Structure> Cerium oxide (HSA-20SP, manufactured by Solvay SpecialChem Japan, CeO ２ powder, average particle size about 10 μm) 700 g, cerium acetate hydrate (Ce(CH ３ CO ２ ) ３ ・1H ２70 g of cellulose acetate (C10) and 700 g of ion-exchanged water were placed in a ball mill and pulverized for 30 minutes. 500 g of ion-exchanged water was added to the pulverized material obtained to obtain a slurry (s). A cordierite honeycomb (ceramic honeycomb) was immersed in the above-mentioned slurry (s). After confirming that the entire honeycomb was immersed, it was pulled out, air-blown, dried at 100°C, and fired at 600°C to obtain a catalyst structure (a). The ceramic honeycomb used here was a cordierite honeycomb, and was a ceramic carrier for catalysts "Honeyceram" (registered trademark) manufactured by NGK INSULATORS, LTD. The cell density of the ceramic honeycomb was 400 cpsi (400 cells / inch). ２ = 62 cells / cm ２ The ceramic honeycomb used had a wall thickness of 4.5 mils (114 μm=0.114 mm) and was obtained by cutting a purchased product into a size of 40 mm in diameter and 50 mm in length using a punching drill and a cutting machine.

[0088] The catalyst structure (a) was again immersed in the slurry (s) and, after confirming that the entire structure was immersed, it was pulled out, air-blown, dried at 100°C, and then fired at 600°C to obtain a catalyst structure (b1). The obtained catalyst structure (b1) contained particulate cerium oxide as a catalyst at 5.1 g / honeycomb structure, i.e., 81 g / L (supported mass per volume), 28 g / m ２ (supported mass per geometric surface area (per unit area of ​​catalyst layer)). The binder contained in the catalyst structure (b1) was cerium acetate hydrate (Ce(CH ３ CO ２ ) ３ ・1H ２ Cerium oxide (CeO) derived from ２ In addition, when a catalyst structure was produced by the same production method as that for catalyst structure (b1), the amount of particulate cerium oxide as a catalyst was 5.4 g / honeycomb structure, that is, 85 g / L (supported mass per volume), 30 g / m ２ (mass of loading per geometric surface area), a supported catalyst structure (b2) was also obtained.

[0089] <Production Example 2> The cell density of the ceramic honeycomb was set to 600 cpsi (600 cells / inch). ２ = 93 cells / cm ２ Catalyst structure (c) was obtained in the same manner as in Example 1, except that the catalyst was replaced with the catalyst of Example 1. The catalyst structure (c) thus obtained contained 5.0 g of particulate cerium oxide per honeycomb structure, i.e., 80 g / L (amount supported per volume), 27 g / m ２ (amount supported per geometric surface area) was supported.

[0090] <Production Example 3> The catalyst structure (c) was again immersed in the slurry (s) and, after confirming that the entire structure was immersed, pulled out, air-blown, dried at 100°C, and then fired at 600°C to obtain a catalyst structure (d). The obtained catalyst structure (d) contained particulate cerium oxide as a catalyst at a rate of 8.6 g / honeycomb structure, i.e., 137 g / L (amount supported per volume), 39 g / m ２ (amount supported per geometric surface area) was supported.

[0091] <Production Example 4> The catalyst structure (d) was again immersed in the slurry (s) and, after confirming that the entire structure was immersed, pulled out, air-blown, dried at 100°C, and then fired at 600°C to obtain a catalyst structure (d). The obtained catalyst structure (e) contained 15.6 g of particulate cerium oxide as a catalyst per honeycomb structure, i.e., 248 g / L (amount supported per volume), 71 g / m ２ (amount supported per geometric surface area) was supported.

[0092] Comparative Production Example 1: Production Example of Alumina Catalyst Structure Cerium oxide (HSA-20SP, manufactured by Solvay SpecialChem Japan, CeO ２700 g of alumina powder as a binder raw material, 21 g of alumina powder as a binder raw material, and 700 g of ion-exchanged water were charged into a ball mill and pulverized for 30 minutes to obtain a slurry (n). A cordierite honeycomb (ceramic honeycomb) was immersed in the above-mentioned slurry (n). After confirming that the entire honeycomb was immersed, the honeycomb was pulled out, air-blown, dried at 100°C, and fired at 600°C to obtain a catalyst structure (e). The ceramic honeycomb used here was the same as that used in Production Example 1. The above-mentioned catalyst structure (e) was again immersed in the above-mentioned slurry (n). After confirming that the entire honeycomb was immersed, the honeycomb was pulled out, air-blown, dried at 100°C, and fired at 600°C to obtain a catalyst structure (f1). The obtained catalyst structure (f1) contained particulate cerium oxide as a catalyst at 4.2 g / honeycomb structure, i.e., 67 g / L (amount supported per volume), 23 g / m ２ (amount supported per geometric surface area) was supported.

[0093] Comparative Production Example 2 The catalyst structure (f1) was again immersed in the slurry (n) and, after confirming that the entire structure was immersed, it was pulled out, air-blown, dried at 100°C, and then fired at 600°C to obtain a catalyst structure (f2). The obtained catalyst structure (f2) contained particulate cerium oxide as a catalyst at a rate of 8.3 g / honeycomb structure, i.e., 132 g / L (amount supported per volume), 46 g / m ２ (amount supported per geometric surface area) was supported.

[0094] Example 1 Carbonate esters were produced under the following conditions using the catalyst structures (b1) and (b2) obtained in Production Example 1. The results are shown in Table 1. Apparatus: Continuous flow reactor (see FIG. 1) Charge molar ratio: (1-propanol (PrOH)) / (2-cyanopyridine (2-CP)) / (catalyst (CeO ２ )) = 600 / 100 / 1 Circulation flow rate: 720 mL / min Residence time: 4 h Reaction pressure: 2.0 MPa Reaction temperature: 132°C Catalyst structure: 2 in total (total catalyst loading: 10.5 g)

[0095] Examples 2 to 6, Comparative Examples 1 and 2 Carbonate esters were produced in the same manner as in Example 1, except that the reaction conditions were changed as shown in Table 1. The results are shown in Table 1.

[0096]

[0097] As is clear from the results in Table 1, in the examples in which cerium oxide derived from cerium acetate was used as a binder, the yield of the target compound, carbonate ester, was high, and it was confirmed that side reactions were suppressed. In these examples, it is believed that by using cerium oxide, which is common to both the catalyst component and the binder, side reactions did not occur, and only the main reaction caused by the catalyst proceeded. In contrast, in the comparative examples in which alumina was used as a binder, the yield of the target carbonate ester was very low, and more by-products were produced than in the examples. In the comparative examples, it is possible that the alumina contained in the binder also acted as a secondary catalyst, causing unintended side reactions.

[0098] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0099] 60 Carbonate ester manufacturing device 100 Carbonate ester manufacturing equipment

Claims

1. A method for producing a carbonate ester, comprising the step of producing a carbonate ester by reacting a monohydric alcohol and carbon dioxide in the presence of a catalyst structure, the catalyst structure including a substrate and a catalyst layer formed on at least a portion of a surface of the substrate and including at least a solid catalyst and a binder, the solid catalyst including particulate cerium oxide, and the binder including cerium oxide as a uniform component.

2. The method for producing a carbonate ester according to claim 1, wherein the cerium oxide contained in the binder is derived from at least one cerium compound selected from the group consisting of cerium acetate, cerium sulfate, and cerium nitrate.

3. The method for producing a carbonate ester according to claim 2, further comprising a binder production step of producing the binder, in which the cerium compound is calcined to obtain cerium oxide in the binder production step.

4. The method for producing a carbonate ester according to claim 2, wherein the content of the cerium oxide derived from the cerium compound in the catalyst layer is 1.0 to 10% by weight based on the total weight of the catalyst layer.

5. The method for producing a carbonate ester according to claim 1, wherein the substrate is a ceramic.

6. The mass of the solid catalyst supported in the catalyst layer is 15 g / m ２ More than 200g / m ２ The method for producing a carbonate ester according to claim 1, wherein:

7. The method for producing a carbonate ester according to claim 1, wherein a hydrating agent is used to remove water produced as a by-product in the reaction for producing the carbonate ester.

8. A catalyst structure for use in the production of a carbonate ester, comprising: a substrate; and a catalyst layer formed on at least a portion of a surface of the substrate and containing at least a solid catalyst and a binder, wherein the solid catalyst contains particulate cerium oxide, and the binder contains cerium oxide as a uniform component.

9. The catalyst structure for producing a carbonate ester according to claim 8, wherein the content of said cerium oxide as a uniform component in said catalyst layer is 1.0 to 10% by weight based on the total weight of said catalyst layer.

10. The catalyst structure for producing a carbonate ester according to claim 8, wherein the substrate is a ceramic.

11. The mass of the solid catalyst in the catalyst layer is 15 g / m ２ More than 200g / m ２ The catalyst structure for producing a carbonate ester according to claim 8, which is as follows:

12. The substrate has a honeycomb structure, and the cell density of the substrate is 15 to 200 (cell / cm ２ 9. The catalyst structure for producing a carbonate ester according to claim 8, wherein the wall thickness of the substrate is 0.01 to 2.0 mm.

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