JP2007209926A - Catalyst for cyclic carbonate synthesis - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for cyclic carbonate synthesis which enables a miniaturization of a reactor by the side of a production volume in the conventional cyclic carbonate manufacture through an increase of an activity per catalyst unit weight or unit surface area, further gives the cyclic carbonate in good yield and at a high selection rate, makes a catalyst separation after a reaction relatively easy also, eliminates waste of resorces economically favorably and safely, and enables an economic production with a more compact device. <P>SOLUTION: The catalyst containing an onium salt compound and mesoporous silica is used. As an onium salt compound, a material selected from ionicity substances containing group 15, preferably, an organic ammonium salt, an organic phosphonium salt, an organic arsonium salt, and an organic antimonium salt is used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalyst used when synthesizing a cyclic carbonate from epoxide and carbon dioxide, and a method for synthesizing a cyclic carbonate using the catalyst.

Cyclic carbonates are widely used as polycarbonate raw materials, intermediates for synthesis of dialkyl carbonates and alkylene glycols, organic solvents, synthetic fiber processing agents, pharmaceutical raw materials, cosmetic additives, electrolyte solutions for lithium batteries, and electrolyte solvents for electric double layer capacitors. It is an important compound used.
Conventionally, this cyclic carbonate is produced by reacting an epoxide and carbon dioxide under appropriate pressure conditions in the presence of a homogeneous catalyst. As such homogeneous catalysts, halides such as alkali metals (Patent Document 1 etc.) and onium salts such as quaternary ammonium salts (Patent Document 2 etc.) have been known for a long time and are used industrially. ing.
Recently, a cyclic carbonate using carbon dioxide in a supercritical state as a reaction medium as well as a reagent in the presence of an alkali metal halide or a fluorinated alkylphosphonium salt, which is a method discovered by the present inventors. Has been proposed (Patent Document 3).

The use of solid catalysts for the purpose of simplifying the catalyst separation process has also been proposed. Heteropolyacids mainly composed of ion exchange resins (Patent Document 4 etc.), basic layered compounds such as hydrotalcite (Patent Document 5), rare earth compounds (Patent Document 6), tungsten oxide or molybdenum oxide (Patent Document 7) ) Etc. are disclosed. Further, it has been reported that magnesia can be used as a solid catalyst (Non-patent Document 1).
However, many solid catalysts are generally not sufficient in terms of activity, yield and selectivity as compared to homogeneous catalysts, and ion exchange resins do not show activity exceeding the performance of molecular catalysts.

  In order to solve these problems, the present inventors previously described that a hybrid catalyst in which silica and an onium salt are covalently bonded or a mixed catalyst thereof has a performance superior to conventional catalysts in both selectivity and activity. In addition, a catalyst capable of facilitating the separation process and significantly improving the catalytic activity at low cost and without impairing selectivity has been proposed (Patent Document 8).

Japanese Patent Publication No.63-17072 JP-A-55-145623 JP 11-335372 A Japanese Patent Laid-Open No. 3-120270 JP-A-11-226413 JP 2002-363177 A Japanese Unexamined Patent Publication No. 7-206847 PCT / JP2005 / 003388 Chem. Commun., 1997, 1129 JACS, 1992, 114, 10834.

  The present invention has been made in order to further improve the invention described in Patent Document 8 described above. By increasing the activity per unit weight or volume of the catalyst, the production amount in the conventional cyclic carbonate production can be increased. Compared with this, it is possible to reduce the size of the reaction apparatus, give cyclic carbonate with high yield and high selectivity, and relatively easy separation of the catalyst after the reaction, which is industrially advantageous and safe and saves resources. An object of the present invention is to provide a catalyst for synthesizing a cyclic carbonate that can be rationally produced in a smaller apparatus.

  As a result of intensive studies to solve the above-described problems of the catalyst, the present inventors have found that a mixture of an onium salt compound and mesoporous silica increases the activity per unit weight of catalyst or unit surface area, thereby increasing the conventional activity. In the production of cyclic carbonate, it is possible to reduce the size of the reactor compared to the production volume, and give cyclic carbonate with high yield and high selectivity, and the catalyst separation after the reaction is relatively easy, which is industrially advantageous. It has been found that the catalyst is useful as a catalyst for synthesizing cyclic carbonates, which is safe and saves resources, and can be rationally produced in a smaller apparatus.

That is, according to this application, the following invention is provided.
<1> A catalyst used when synthesizing a cyclic carbonate from epoxide and carbon dioxide, comprising an onium salt compound and mesoporous silica.
<2> The catalyst as described in <1> above, wherein the onium salt compound is an ionic substance containing Group 15.
<3> The catalyst according to <2>, wherein the ionic substance containing Group 15 is a substance selected from an organic ammonium salt, an organic phosphonium salt, an organic arsonium salt, and an organic antimonium salt.
<4> The catalyst according to <3>, wherein the salt selected from organic ammonium salts, organic phosphonium salts, organic arsonium salts, and antimonium salts is a halide.
<5> Anion of a salt selected from organic ammonium salt, organic phosphonium salt, organic arsonium salt and organic antimonium salt is sulfate ion, hydrogen sulfate ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, cyanide The catalyst according to <4>, wherein the catalyst is one selected from ions, isothiocyanate ions and isocyanate ions.
<6> The catalyst according to any one of <1> to <5> above, wherein the mesoporous silica has cylindrical pores having a pore diameter of 1 nm to 10 nm.

The catalyst of the present invention can reduce the size of the reactor compared to the production amount in conventional cyclic carbonate production by increasing the activity per unit weight or surface area of the catalyst, and further, with high yield and high selectivity. Cyclic carbonate is provided, and the catalyst separation after the reaction is relatively easy, and it is industrially advantageous, safe and less wasteful of resources, and can be produced rationally with a smaller apparatus.
Therefore, according to the catalyst of the present invention, an electrolyte solvent for lithium batteries, an organic solvent, a synthetic fiber processing agent, a pharmaceutical raw material, and a cyclic carbonate useful as an intermediate for synthesizing alkylene glycol and dialkyl carbonate, epoxide and carbon dioxide. Can be obtained with extremely high efficiency and high selectivity. It can also be used in a flow reaction system.

The synthesis reaction of the cyclic carbonate from the epoxide of the present invention and carbon dioxide is represented by the following general formula (1).

In the general formula (1), R ₁ , R ₂ , R ₃ and R ₄ are a hydrogen atom, a substituted or unsubstituted organic group, and more specifically an alkyl group, an aryl group, an alkenyl group, a cyclo Represents an alkyl group or an arylalkyl group, and may be the same or different from each other; Substituents here are halogen atoms, halogenated alkyl groups, dialkylamino groups, nitro groups, carbonyl groups, carboxyl groups, alkoxy groups, acetoxy groups, cyano groups, hydroxyl groups, mercapto groups, sulfone groups, etc. It is not limited to the substituent. Any one or more of R _{1 to} R ₄ may be bonded in a cyclic manner, and may contain an unsaturated bond.

The epoxide used in the present invention is a compound represented by the following general formula (2).

In the general formula (2), R ₁ , R ₂ , R ₃ and R ₄ are the same as in the general formula (1). Any one or a plurality of R _{1 to} R ₄ may be bonded cyclically, and may contain a hetero element or an unsaturated bond. Specifically, ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, vinyl ethylene oxide, trifluoromethyl ethylene oxide, cyclohexene oxide, styrene oxide, butadiene monooxide, butadiene dioxide, chloral, 2-methyl-3-phenylbutene oxide, Examples include pinene oxide, tetracyanoethylene oxide, and the like, but the present invention is not limited to these epoxides, and includes at least one three-membered ring composed of two carbon atoms and one oxygen atom in the structural formula. Any so-called epoxy compound can be used.

The cyclic carbonate produced in the present invention is a compound represented by the following general formula (3).

In the general formula (3), R ₁ , R ₂ , R ₃ and R ₄ are the same as those in the general formula (1). Any one or a plurality of R _{1 to} R ₄ may be bonded cyclically, and may contain a hetero element or an unsaturated bond. Specifically, ethylene carbonate, propylene carbonate, butylene carbonate, isobutylene carbonate, trifluoromethyl ethylene carbonate, vinyl ethylene carbonate, cyclohexene carbonate, styrene carbonate, butadiene monocarbonate, butadiene dicarbonate, chloromethyl carbonate, pinene carbonate, tetracyano Ethylene carbonate and the like are exemplified, but the cyclic carbonate produced in the present invention is not limited to these, and any so-called cyclic carbonate containing a 5-membered ring having an O—CO—O bond may be used.

  The catalyst used in the present invention is a mixed catalyst containing an onium salt compound and mesoporous silica. This mixed catalyst does not require any special pretreatment, and usually works automatically and effectively only by mixing and using an onium salt compound and mesoporous silica.

The method for mixing substances in the mixed catalyst of the present invention does not require any pretreatment. However, when used in a batch reaction, mesoporous silica is first dissolved in an onium salt solvent in order to develop its activity immediately after the start of charging. It is effective to keep the onium salt well dispersed on the silica surface. As a solvent to be used at this time, it is necessary to dissolve onium salts well. Suitable substances for this purpose include amides, esters, ketones, alcohols, etc., but considering the purification after the reaction, the most suitable solvent is to use the product cyclic carbonate itself.
In the examples described later, different types of cyclic carbonates are used as solvents in order to facilitate the distinction from the products and to suppress the formation of by-products.

As used herein, “onium salt compound” means an ionic substance containing a Group 15 element.
Ionic substances containing these Group 15 elements can generally be represented by the general formula ER ₅ R ₆ R ₇ R ₈ X.
Here, E represents one of group 15 elements (nitrogen, phosphorus, arsenic, antimony, bismuth).
R _{5 to} R ₈ each represents an organic group which may be substituted, and more specifically represents an alkyl group, an aryl group or the like, and 2 to 4 of them may be bonded in a cyclic manner. Or the ring in this case may include a double bond or a triple bond. Accordingly, nitrogen-containing heterocyclic salts such as imidazolinium, pyridinium, tetrazolinium and the like are also included.

X is an anion, halide ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, nitrate ion, sulfate ion, organic acid ion, carbonate ion, bicarbonate ion, borate ion, hydrogen borate ion, boron Acid hydrogen ion, alkyl or aryl sulfate ion, mono or dialkyl phosphate ion, mono or diaryl phosphate ion, mono or dialkyl borate ion, cyanide ion, thiocyanate ion, cyanate ion, carboxylate ion, tetrafluoroborate ion, etc. One or a plurality of anions selected from, preferably halide ions, sulfate ions, cyanide ions, phosphate ions, isocyanate ions, isothiocyanate ions, etc., more preferably chloride ions, bromides. Ion, iodide Io Halide ions such as
The onium salt compound preferably used in the present invention is at least one salt selected from organic ammonium salts, organic phosphonium salts, organic arsonium salts, and organic antimonium salts.

  Specific examples of such ionic substances containing Group 15 elements include quaternary ammonium halides such as tetraethylammonium bromide, cetyltrimethylammonium bromide and benzalkonium chloride, triphenylbutylphosphonium chloride and tetrabutylphosphonium iodide. And quaternary phosphonium halides such as tetraphenylphosphonium bromide, quaternary arsonium halides such as triphenylbenzylarsonium iodide and tetraphenylarsonium chloride, and quaternary antimonium halides such as tetraphenylantimonium bromide.

  “Mesoporous silica” used in the present invention is a porous body having a skeleton mainly composed of silica and having uniform nanopores on the order of several nanometers, and the pores are arranged in a hexagonal or cubic phase. A thing with regularity.

  Specifically, this mesoporous silica has a structure in which micropores having extremely uniform pore diameters are arranged in a hexagonal shape as schematically shown in FIG. 1, and such a micropore structure has an excellent tertiary structure. It can be said that it has original high regularity.

  In this case, either a gel-like hydrolyzate is arranged around the surfactant arranged in a three-dimensional highly regular columnar shape, or a complex of the gel-like hydrolyzate and the surfactant is baked. The obtained fired body is preferable. As the fired body, a fired body at 350 to 700 ° C. for 1 hour or longer is preferable.

  This three-dimensional high regularity can be evaluated by the half-value width of the X-ray diffraction peak of the (100) plane of mesoporous silica. In general, inorganic materials have higher crystallinity as the half-value width of the X-ray diffraction peak is smaller. However, in the case of a mesoporous body, the half-value width correlates with the regularity of pores (pore size distribution and three-dimensional arrangement). It can be said that the three-dimensional high regularity is excellent when the half width of the X-ray diffraction peak of the (100) plane is 1 ° or less. The full width at half maximum is preferably 0.8 ° or less, more preferably 0.6 ° or less, and particularly preferably 0.3 ° or less.

  The pore size of mesoporous silica is preferably 1 to 10 nm, more preferably 1.2 to 6 nm, and more preferably 1.2 to 4.0 nm. If the pore size is too small, the diffusion is slowed down, so that the activity may be reduced compared to the surface area. On the other hand, if the pore diameter is too large, the special effect due to being mesoporous is lost.

The pore diameter of this mesoporous silica is defined as the pore diameter at the peak of the pore diameter distribution obtained by the gas adsorption method as seen in JP-A-2005-162596. In addition, gas adsorption measurement is performed at −196 ° C. after drying the mesoporous silica at 300 ° C. under reduced pressure (vacuum degassing) for 8 hours. Vacuum drying pressure during preferably not more than 10 ^-1 Pa, more preferably between 10 ^-2 Pa or less.

In the present invention, the components of mesoporous silica are not limited as long as the main component is silica.
Silica may contain a trace amount or a small amount of carbon, lead, tin, boron, aluminum, gallium, indium, nitrogen, phosphorus, arsenic, antimony, titanium, zircon, hafnium, or the like.
Moreover, you may contain organic substance in parts other than frame | skeleton. For example, organic substances such as a cationic surfactant may be contained in the fine pores of the dried mesoporous body before firing.

The mesoporous silica of the present invention, the surface area to weight ratio surface area of 500~2000m ² · g ^-1, preferably the surface area of the 600~1800m ² · g ^-1, more preferably 800~1600cm ² · g ^-1 Those having are preferred.

  Although there is no restriction | limiting in particular in the form of the mesoporous silica of this invention, Usually, it is a fine particle form, a thin film form, or a spherical or cylindrical particle | grain with an average particle diameter of 0.1-10 mm.

  Examples of the mesoporous silica preferably used in the present invention include those readily available from J. S. Beck et al. Am. Chem. Soc. , 114, 10834 (1992), and mesoporous silica (MCM-41) obtained by hydrothermal synthesis using an assembly of a surfactant composed of alkyltrimethylammonium as a template.

  In addition, acid-base catalyzed hydrolytic condensation from silica or other metal oxide alkoxides using the same molecular aggregate as found in JP-A-2005-162596 as a template is obtained by drying under reduced pressure. Also effective is mesoporous silica (MPS-C16) produced by sintering a solid material. This solid is more preferable than MCM-41 in terms of mechanical strength, chemical strength, and small bulk volume per surface area.

The mesoporous silica (MPS-C16) is a metal alkoxide in a reaction solution containing (a) a silicon alkoxide and / or a polycondensate thereof, a surfactant, a solution comprising water and alcohol, and an acid. And / or the said polycondensate is hydrolyzed and the powdery or granular nanoporous body is efficiently produced | generated by the method of volatilizing the solvent of the obtained hydrolyzate solution (b).
The solvent of the hydrolyzate solution is preferably volatilized in a reduced pressure atmosphere. By volatilizing in a reduced-pressure atmosphere, the solvent can be efficiently removed. It is preferable to volatilize the solvent while reducing the pressure to such a level that the hydrolyzate solution does not boil. The solvent is preferably volatilized while forcibly causing a flow so as to maintain the uniformity of the hydrolyzate solution. The solvent is preferably volatilized at 0 to 70 ° C. It is preferable to make the hydrolyzate solution acidic to volatilize the solvent.

  The silicon alkoxide and / or the polycondensate may contain at least one metal alkoxide selected from the group consisting of aluminum, titanium and zirconium and / or a polycondensate thereof in addition to silicon. Good. The surfactant is preferably a cationic surfactant or a nonionic surfactant, and more preferably a quaternary ammonium surfactant.

  The mesoporous silica used in the present invention as described above has a sufficiently large specific surface area per unit weight or unit volume and has sufficient mechanical and chemical stability.

  If the amount of the onium salt compound and silica is too small, only adsorption to an inactive adsorption point on silica occurs, and no activity appears. On the other hand, if the amount of onium salt is too large, the solution becomes viscous and a solid is precipitated, which is disadvantageous for catalyst separation. The weight ratio of onium salt to silica is preferably from 0.1: 1 to 10: 1, more preferably from 0.5: 1 to 2: 1.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited at all by these examples.

Reference example 1
[Synthesis of mesoporous silica (MPS-C16)]
19.2 g of cetyltrimethylammonium chloride and 138.0 g of ethanol (purity 99.5% by volume or more) were placed in a 500 mL glass beaker and stirred at room temperature for 15 minutes using a magnetic stirrer. Next, 62.5 g of tetraethylorthosilicate (purity 98%) and 54.0 g of aqueous hydrochloric acid (10 ⁻³ M) were added and stirred at room temperature for 1 hour to obtain a transparent hydrolyzate solution. According to the physical property constant estimation method [Chemical Engineering Handbook 3rd edition Maruzen Co., Ltd.], the hydrolyzate solution had a kinematic viscosity of 2 cm ² / sec.

Transfer this hydrolyzate solution to a 1000 mL eggplant-shaped flask (the inner diameter of the largest part: 13.2 cm), and react for 90 minutes using a rotary evaporator (40 rpm) at a temperature of 25 ° C and a reduced pressure of 60 hPa. To obtain a white precipitate. Next, the temperature was raised to 60 ° C and the degree of vacuum was 10
The white precipitate was sufficiently dried by raising to hPa. The obtained solid was baked at 600 ° C. to remove the cationic surfactant. The structural regularity of the porous structure was evaluated by X-ray diffraction analysis (XRD) of the obtained fired body and adsorption isotherm by nitrogen gas. Graphs showing the X-ray diffraction pattern and nitrogen adsorption isotherm of mesoporous silica (MPS-C16) are shown in FIGS. It was found that mesoporous silica has high three-dimensional high regularity.
The surface area and regular pore size data obtained in this experiment are shown in Table 1.

Reference example 2
[Synthesis of mesoporous silica (MCM-41)]
40 g of water, 18.7 g of sodium silicate 28.7% silica solution and 1.2 g of sulfurous acid are mixed and stirred. After stirring for 10 minutes, a solution of 16.77 g of C ₁₆ H ₃₃ (CH ₃ ) ₃ NBr in 50.23 g of water is added and stirring is continued for another 30 minutes. An additional 20 g of water is added to the gel. The gel is heated at 100 ° C. for 144 hours. By this operation, a solid was obtained from the aqueous solution.
This solid is recovered and heated at 540 ° C. for 1 hour. The obtained solid was evaluated for structural regularity of the porous structure by XRD and adsorption isotherm by nitrogen gas. The X-ray explanation pattern and the graph showing the nitrogen adsorption isotherm of mesoporous silica (MCM-41) almost coincided with the literature. The surface area and regular pore size data obtained in this experiment are shown in Table 1. As in the literature, mesoporous silica was found to have high three-dimensional high regularity.

In addition, in order to measure the bulk volume per unit mass of the mesoporous silica obtained in Reference Examples 1 and 2 in a smaller amount according to JIS K1550, use a 10 ml graduated cylinder for 5 to 8 ml samples. After weighing, weigh accurately to the unit of 10 mg and tap the graduated cylinder filled with silica on the rubber plate for about 1 minute to pack the powder. Was obtained by dividing the weight of silica by the volume obtained by accurately reading up to 0.05 ml. The results are shown in Table 1. In Table 1, a similar experiment was performed on one-side separation silica gel SG60N, and the values are also shown in the same table.
From Table 1, it can be seen that MPS-C16 has a much higher bulk density than MCM-41, and the surface area per unit volume is double while the surface area per unit weight is similar. On the other hand, the silica gel SG60N for separation has a medium bulk density, but the surface area per unit weight is about half that of mesoporous silica, and the surface area per unit volume is between the two mesoporous silicas.

Examples 1-2, Comparative Example 1
A certain amount of commercially available tetrabutylphosphonium bromide as a catalyst, 200 mg of each of the two types of mesoporous silica and ordinary silica gel shown in Table 1, 2.6 g of ethylene carbonate (approximately 2.0 ml when dissolved), and 50 mg of adamantane as an internal standard Into a 20 ml autoclave equipped with a stirrer, pressure gauge and needle valve under argon, 2.0 ml (28.6 mmol) of propylene oxide was added using a syringe and sealed. filling of liquid CO _2. This is sealed and heated for about 5 minutes with stirring in an oil bath set to a predetermined temperature. In addition, pressurize high-pressure CO ₂ from the valve to maintain a constant pressure, and continue the heating to urge the reaction. If the pressure drops significantly during the reaction, CO ₂ is further added from the needle valve, and the reaction is continued for one hour while keeping the internal pressure almost constant. After the reaction, when the pressure of the vessel is released, the gas released is trapped through the DMF trap as completely as possible to the raw material propylene oxide remaining in the gas phase and part of the product propylene carbonate. The combined DMF solution and the reaction solution were thoroughly homogenized and filtered, and the solution obtained by mixing the filtered silica gel together with the washing solution washed with DMF again was analyzed by gas chromatography. The yield was calculated from the amount of propylene carbonate produced, and the selectivity was calculated in consideration of the amount of by-product produced. In addition, when the raw material from which water | moisture content was fully removed was used, all the selectivity exceeded 99.8%. The yield results are shown in Table 2.

  As is apparent from Table 1 above, mesoporous silica (Example 1: MPS-C16, Example 2: MCM-) compared to the case where normal silica (Comparative Example 1: SG60N) of the same weight was used as a catalyst. It can be seen that the yield is clearly improved by using 41). Thus, the advantage of using mesoporous silica having a large surface area compared with ordinary silica is obvious.

The comparison of the yields in the above Examples and Comparative Examples was carried out by an experiment in which the weight of silica was aligned (yield per unit weight). The mesoporous silica was about 1.5 times higher than SG60N, which is a silica gel for separation. Since it is a surface area, the catalyst performance per unit surface area was compared by comparing again with the reaction rate constant (k _s ) converted into the silica unit surface area (100 m ² ). The results are shown in Table 3.
The reaction rate constant k _s / min ⁻¹ m ⁻² per unit surface area is obtained by dividing the pseudo first order reaction rate constant (k ′: unit is min ⁻¹ ) of the system by the surface area of silica. It was.
k ′ = − ln (1-y (t)) / t
t: Reaction time (min)
y (t): molar fraction of product at time t (yield)

  From Table 3, when a relatively large amount of tetraethylammonium salt is used relative to silica, the activity is saturated in silica gel 60N, whereas the activity increases in two mesoporous silicas. It can be seen that it exceeds that of 1.5 times or 2.3 times, respectively. This fact suggests that not only the surface but also the ammonium salt placed in the pores may have a higher activity than that in the normal liquid phase.

Furthermore, the reaction rate constant (k _s ) converted to unit volume (1 cm ³ ) was compared in the above Examples and Comparative Examples, and the catalyst performance per bulk volume was compared. The results are shown in Table 4.
The reaction rate constant k _v (min ⁻¹ · cm ^-3 ) per unit volume should be divided by the volume of silica using the quasi-first order reaction rate constant (k ′: unit is min ⁻¹ ) of the system. Sought by.
k ′ = − ln (1-y (t)) / t
t: Reaction time (min)
y (t): molar fraction of product at time t (yield)

From Table 4, mesoporous silica shows higher activity than silica gel 60N when the same amount or more of onium salt is added. In particular, this effect suggests that MPS-C16 is large, and not only the silica surface but also the onium salt in the pores may express higher catalytic activity than that in solution.
MPS-C16 is more uniform and dense and has a higher bulk density than MCM-41. This is probably expected to be related to the low external surface area of the porous solid catalyst.

  From the above, it became clear that the catalytic activity per unit weight of silica can be increased by using mesoporous silica and onium salt having a high surface area. This effect is particularly noticeable with MCM-41. On the other hand, the activity per bulk volume of the catalyst particles can be increased by using a specific mesoporous silica such as MPS-C16. In these mesoporous silicas, not only the surface but also the onium salt in the mesopores has a higher catalytic activity than that in the solution, and it is expected that the silica acts as a place to express the high activity. By using these mesoporous silicas, the cyclic carbonate can be synthesized more efficiently, and the production efficiency in a small reactor can be improved.

The schematic sectional drawing of the fine structure of mesoporous silica. X-ray crystal diffraction data of mesoporous silica (MPS-C16). Nitrogen adsorption isotherm data at -196 ° C for mesoporous silica (MPS-C16).

Claims (6)

A catalyst used when synthesizing a cyclic carbonate from epoxide and carbon dioxide, comprising an onium salt compound and mesoporous silica. 2. The catalyst according to claim 1, wherein the onium salt compound is an ionic substance containing a Group 15. The catalyst according to claim 2, wherein the ionic substance containing Group 15 is a substance selected from organic ammonium salts, organic phosphonium salts, organic arsonium salts, and organic antimonium salts. The catalyst according to claim 3, wherein the salt selected from an organic ammonium salt, an organic phosphonium salt, an organic arsonium salt, and an antimonium salt is a halide. The anion of the salt selected from organic ammonium salt, organic phosphonium salt, organic arsonium salt and organic antimonium salt is sulfate ion, hydrogen sulfate ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, cyanide ion, isothiocyanate. The catalyst according to claim 4, wherein the catalyst is one selected from an acid ion and an isocyanate ion. The catalyst according to any one of claims 1 to 5, wherein the mesoporous silica has cylindrical pores having a pore diameter of 1 nm to 10 nm.

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