Zirconium alkoxide-supported metal oxide, method for producing zirconium alkoxide-supported metal oxide, and method for producing carbonic acid diester

Abstract

To provide a novel zirconium alkoxide material usable as a heterogeneous catalyst.SOLUTION: Provided is a zirconium alkoxide-supported metal oxide that contains a carrier and a zirconium alkoxide supported on the carrier, wherein the carrier is a metal oxide.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a zirconium alkoxide-supported metal oxide, a method for producing the zirconium alkoxide-supported metal oxide, and a method for producing a dialkyl carbonate.

Background Art

[0002] Zirconium alkoxide is a compound used as a catalyst for various organic synthesis reactions.

[0003] For example, Patent Document 1 proposes a method for producing an organic carbonate by reacting alkoxysilanes with carbon dioxide using zirconium alkoxide as a catalyst.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In organic synthesis using zirconium alkoxide as a catalyst, zirconium alkoxide is generally used in a dissolved state in the reaction solution and discarded without being recovered after the reaction.

[0006] In recent years, the awareness of reducing environmental impact has been increasing, and the development of heterogeneous catalysts that can be separated and recovered after the reaction has been actively carried out. An object of the present disclosure is to provide a novel zirconium alkoxide material that can be used as a heterogeneous catalyst.

Means for Solving the Problems

[0007] The inventors have found that the above problems can be solved by using a metal oxide or a metal oxide composite as a carrier and supporting zirconium alkoxide thereon. That is, the present disclosure has the following gist.

[0008] [1] A zirconium alkoxide-supported metal oxide comprising a carrier and zirconium alkoxide supported on the carrier, wherein the carrier is a metal oxide. [2] The zirconium alkoxide-supported metal oxide according to [1], wherein the zirconium alkoxide is a compound represented by the general formula (I). (R 1 ) 4-p Zr(OR 1 ) p (I) (R 1 is each independently a hydrocarbon group which may have a substituent; p is an integer of 1 or more and 4 or less.) [3] The zirconium alkoxide-supported metal oxide according to [1] or [2], wherein the metal oxide contains an oxide of one or more metals selected from the group consisting of rare earth metals, Group 4 metals of the periodic table, Group 13 metals of the periodic table, and Group 14 metals of the periodic table. [4] The zirconium alkoxide-supported metal oxide according to any one of [1] to [3], wherein the carrier is core-shell type particles. [5] The zirconium alkoxide-supported metal oxide according to [4], wherein the core of the core-shell type particles is silica and the shell of the core-shell type particles is ceria. [6] The zirconium alkoxide-supported metal oxide according to [4] or [5], wherein the content of the core with respect to the total amount of the core-shell type particles is 10% by weight or more and 99% by weight or less, and the content of the shell with respect to the total amount of the core-shell type particles is 1% by weight or more and 90% by weight or less. [7] The supported amount of the zirconium alkoxide is 1% by weight or more and 20% by weight or less based on the total amount of the zirconium alkoxide-supported metal oxide, the zirconium alkoxide-supported metal oxide according to any one of [1] to [6]. [8] The zirconium alkoxide-supported metal oxide according to any one of [1] to [7], which is a catalyst used in the reaction for synthesizing a diester carbonate from an alkoxysilane and carbon dioxide. [9] After bringing a solution containing a zirconium alkoxide into contact with a carrier, a supporting step of supporting the zirconium alkoxide on the carrier by removing the solvent of the solution is included. A method for producing a zirconium alkoxide-supported metal oxide, wherein the carrier is a metal oxide.

[10] The method for producing a zirconium alkoxide-supported metal oxide according to [9], wherein the zirconium alkoxide is a compound represented by the general formula (I). (R 1 ) 4-p Zr(OR 1 ) p (I) (R 1 is each independently a hydrocarbon group which may have a substituent; p is an integer of 1 or more and 4 or less.)

[11] The method for producing a zirconium alkoxide-supported metal oxide according to [9] or

[10] , wherein the metal oxide contains an oxide of one or more metals selected from the group consisting of rare earth metals, Group 4 metals of the periodic table, Group 13 metals of the periodic table, and Group 14 metals of the periodic table.

[12] The method for producing a zirconium alkoxide-supported metal oxide according to any one of [9] to

[11] , wherein the carrier is a core-shell type particle.

[13] The method for producing a zirconium alkoxide-supported metal oxide according to

[12] , wherein the core of the core-shell type particle is silica and the shell of the core-shell type particle is ceria.

[14] A method for producing a carbonate diester, comprising a reaction step of reacting an alkoxysilane with carbon dioxide in the presence of the zirconium alkoxide-supported metal oxide according to any one of [1] to [8].

[15] The method for producing a carbonic acid diester according to

[14] , wherein the alkoxysilane is at least one selected from the group consisting of compounds represented by general formula (A1) and compounds represented by general formula (A2). (R a2 ) 4-n1 Si(OR a1 ) n1 (A1) R a3 [Si(R a2 ) 3-n2 (OR 1 ) n2 ] m (A2) (R a1 are each independently a hydrocarbon group which may have a substituent; R a2 are each independently a hydrocarbon group which may have a substituent; R a3 are each independently a hydrocarbon group which may have a substituent; n1 is an integer of 1 or more and 4 or less; n2 is an integer of 1 or more and 3 or less; m is an integer of 2 or more and 20 or less; and n1 is When the integer is 2 or more and 4 or less, two ORs bonded to the same Si atom a1 R a1 may be bonded to each other to form a ring; when n1 is an integer of 1 or more and 3 or less, OR a1 Group R a1 and R a2 may be bonded to each other to form a ring; when n2 is 2 or 3, two OR a1 R a1 may be bonded to each other to form a ring; when n2 is 1 or 2, OR bonded to the same Si atom a1 Group R a1 and R a2 may be bonded to each other to form a ring. [Effects of the Invention]

[0009] According to the present disclosure, a novel zirconium alkoxide material that can be used as a heterogeneous catalyst can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Modes for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present disclosure, and the present disclosure is not limited to these contents, and various modifications can be made and implemented within the scope of the gist.

[0012] In the present disclosure, the descriptions of "X or more and Y or less" and "X to Y" representing a numerical range mean a numerical range including the lower limit and the upper limit which are the endpoints, unless otherwise specified. When the lower limit value and the upper limit value of the numerical range are separately described, the numerical range can be a combination of any lower limit value and any upper limit value.

[0013] In the present disclosure, the descriptions of "content of X" and "usage amount of X" mean "total content of X" and "total usage amount of X", respectively, when two or more types of X are used in combination, unless otherwise specified.

[0014] 1. Zirconium alkoxide-supported metal oxide The zirconium alkoxide-supported metal oxide according to the first embodiment of the present disclosure includes a carrier and zirconium alkoxide supported on the carrier, and the carrier is a metal oxide. The zirconium alkoxide-supported metal oxide according to the present embodiment is not limited in its use, but can be suitably used as a heterogeneous catalyst for organic synthesis reactions. Examples of the organic synthesis reaction include reactions using zirconium alkoxide as a catalyst, such as a reaction for synthesizing a diester carbonate from an alkoxysilane and carbon dioxide described later, but are not limited thereto. Furthermore, since the zirconium alkoxide-supported metal oxide according to the present embodiment can be easily separated, recovered, and reused after the reaction, it is expected to contribute to reducing the environmental load.

[0015] 1-1. Carrier The zirconium alkoxide-supported metal oxide contains a metal oxide as a carrier. The carrier may be a carrier composed of only one kind of metal oxide, or may be a metal oxide composite containing two or more kinds of metal oxides. The metal oxide may be an oxide of one kind of metal, or may be a composite oxide of two or more kinds of metals.

[0016] In the present disclosure, "metal" shall include metalloids. Specific metalloids include, for example, boron, silicon, germanium, arsenic, selenium, tin, antimony, tellurium, bismuth, polonium, and astatine.

[0017] The shape of the metal oxide is not particularly limited and may be any shape such as particles, fibers, films, plates, etc. However, it is preferably particles or fibers, and more preferably particles.

[0018] When the metal oxide has a particulate shape, the average particle size of the particles is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, even more preferably 50 nm or more, and is preferably 1,000 μm or less, more preferably 500 μm or less, still more preferably 100 μm or less, even more preferably 1,000 nm or less, and particularly preferably 500 nm or less. That is, examples of the suitable range of the average particle size of the metal oxide particles include ranges of 5 nm or more and 1,000 μm or less, 10 nm or more and 500 μm or less, 10 nm or more and 100 μm or less, 20 nm or more and 1,000 nm or less, and 50 nm or more and 500 nm or less.

[0019] In the present disclosure, the "average particle size" is D50 (median diameter), which is the 50% particle size in the volume-based cumulative particle size distribution measured by a laser diffraction particle size analyzer.

[0020] The specific surface area of the metal oxide is not particularly limited, but is preferably 0.4 m 2 / g or more, more preferably 5 m 2 / g or more, still more preferably 50 m 2 / g or more, even more preferably 100 m 2 / g or more, particularly preferably 200 m 2 / g or more, and is preferably 1,000 m 2 / g or less, more preferably 800 m 2 / g or less, still more preferably 600 m 2 / g or less, even more preferably 500 m 2 / g or less, particularly preferably 400 m 2 / g or less. That is, examples of the suitable range of the specific surface area of the metal oxide include ranges of 0.4 m 2 / g or more and 1,000 m 2 / g or less, 5 m 2 / g or more and 800 m 2 / g or less, 50 m 2 / g or more and 600 m 2 / g or less, 100 m 2 / g or more and 500 m 2 / g or less, and 200 m 2 / g or more and 400 m2 The range is below / g.

[0021] In the present disclosure, the specific surface area of the metal oxide is measured by the nitrogen adsorption method. For measuring the specific surface area of the metal oxide, a specific surface area and pore size distribution measuring device (for example, "BELSROP MINI X" manufactured by MicrotracBEL Corporation) can be used.

[0022] The metal oxide is not particularly limited, but in order to use the zirconium alkoxide-supported metal oxide as a heterogeneous catalyst, it is preferably insoluble or hardly soluble in an organic solvent and an aqueous solvent. Examples of such metal oxides preferably include oxides of one or more metals selected from the group consisting of rare earth metals, Group 4 metals of the periodic table, Group 13 metals of the periodic table, and Group 14 metals of the periodic table. When the metal oxide is a metal oxide composite, the metal oxide composite is preferably a composite of two or more of the above metal oxides.

[0023] Examples of rare earth metals include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, and cerium is preferred.

[0024] Examples of Group 4 metals of the periodic table include titanium, zirconium, hafnium, and rutherfordium, and titanium or zirconium is preferred.

[0025] Examples of Group 13 metals of the periodic table include aluminum, gallium, indium, thallium, and nihonium, and aluminum is preferred.

[0026] Examples of Group 14 metals of the periodic table include silicon, germanium, tin, lead, and flerovium, and silicon is preferred.

[0027] Specific examples of the metal oxide include magnesium oxide (MgO), calcium oxide (CaO ) Vanadium pentoxide (V2O5), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), iron(II) oxide (FeO), iron(III) oxide (Fe2O3), copper(I) oxide (Cu2O), copper(II) oxide CuO, zinc oxide (ZnO), ceria (CeO2), zirconia (ZrO2), titania (TiO2), alumina (Al2O3), and silica (SiO2) etc. are preferably mentioned, and ceria (CeO2), zirconia (ZrO2), titania (TiO2), alumina (Al2O3), and silica (SiO2) etc. are particularly preferably mentioned.

[0028] When the metal oxide is a metal oxide composite, the metal oxide composite may be a composite in which two or more metal oxides are uniformly or non-uniformly mixed, or may be a multilayer structure in which the layers of each metal oxide overlap, but it is preferably a multilayer structure. In particular, when the carrier has a particle shape, the carrier is preferably a core-shell type particle among the multilayer structures. The core-shell type particle is a particle having a core composed of one metal oxide and a shell composed of another metal oxide.

[0029] The combination of the metal oxide constituting the core of the core-shell type particle and the metal oxide constituting the shell is not particularly limited, and for example, the above-mentioned metal oxides can be arbitrarily combined. That is, as the core-shell type particle, those in which the core and the shell are composed of one or more materials selected from magnesium oxide (MgO), calcium oxide (CaO), vanadium pentoxide (V2O5), niobium pentoxide (Nb2O5), tantalum pentoxide (Ta2O5), iron(II) oxide (FeO), iron(III) oxide (Fe2O), copper(I) oxide (Cu2O), copper(II) oxide CuO, zinc oxide (ZnO), ceria (CeO2), zirconia (ZrO2), titania (TiO2), alumina (Al2O3), and silica (SiO2) are preferably mentioned, and those in which the core and the shell are composed of ceria (CeO2), zirconia (ZrO2), titania (TiO2), alumina (Al2O3), or silica (SiO2) are particularly preferably mentioned.

[0030] As suitable core-shell type particles, those having a core made of silica and a shell made of ceria (CeO₂), zirconia (ZrO₂), titania (TiO₂), alumina (Al₂O₃), or silica (SiO₂) are preferred, and those having a core made of silica and a shell made of ceria (CeO₂) are more preferred. The zirconium alkoxide-supported metal oxide using such core-shell type particles as a carrier is expected to exhibit high catalytic activity in the carbonic diester synthesis reaction described later.

[0031] The content of the core with respect to the total amount of the core-shell type particles is preferably 5% by weight or more, more preferably 10% by weight or more, still more preferably 15% by weight or more, even more preferably 20% by weight or more, and is preferably 99% by weight or less, more preferably 95% by weight or less, still more preferably 90% by weight or less, even more preferably 80% by weight or less, particularly preferably 70% by weight or less, and most preferably 60% by weight or less. That is, the suitable range of the content of the core with respect to the total amount of the core-shell type particles includes, for example, ranges of 5% by weight or more and 99% by weight or less, 10% by weight or more and 95% by weight or less, 10% by weight or more and 90% by weight or less, 15% by weight or more and 80% by weight or less, 15% by weight or more and 70% by weight or less, and 20% by weight or more and 60% by weight or less.

[0032] The content of the shell with respect to the total amount of the core-shell type particles is preferably 1% by weight or more, more preferably 5% by weight or more, still more preferably 10% by weight or more, even more preferably 20% by weight, particularly preferably 30% by weight or more, and most preferably 40% by weight or more, and is preferably 95% by weight or less, more preferably 90% by weight or less, still more preferably 85% by weight or less, and even more preferably 80% by weight or less. That is, the suitable range of the content of the shell with respect to the total amount of the core-shell type particles includes, for example, ranges of 1% by weight or more and 95% by weight or less , 5% by weight or more and 90% by weight or less, 10% by weight or more and 90% by weight or less, 20% by weight or more and 85% by weight or less, 30% by weight or more and 85% by weight or less, and 40% by weight or more and 80% by weight or less.

[0033] By setting the content ratio of the core and silica within the above range, when the zirconium alkoxide-supported metal oxide is used as a catalyst for the carbonic acid diester synthesis reaction described below, high catalytic activity can be maintained even if it is recovered and reused after the reaction. As shown in the examples described below, the maintainability of the catalytic activity is high when the content of the core in the total amount of the core-shell type particles is 20% by weight or more and 60% by weight or less, and the content of the shell is 40% by weight or more and 80% by weight, and is particularly high when the content of the core in the total amount of the core-shell type particles is 20% by weight or more and 40% by weight or less, and the content of the shell is 60% by weight or more and 80% by weight. In the case of core-shell type particles in which the core is silica (SiO2) and the shell is ceria, such a tendency is particularly strong.

[0034] The content ratio of the core and silica in the core-shell type particles is measured by fluorescent X-ray analysis (XRF).

[0035] 1-2. Zirconium alkoxide The zirconium alkoxide supported on the metal oxide is not particularly limited, but a tetravalent zirconium alkoxide represented by the general formula (I) is preferably mentioned. (R 1 ) 4-p Zr(OR 1 ) p (I)

[0036] In the general formula (I), R 1 is each independently a hydrocarbon group which may have a substituent.

[0037] R 1 The carbon number of the hydrocarbon group which may have a substituent represented by is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and is preferably 20 or less, more preferably 12 or less, and still more preferably 8 or less. That is, examples of the suitable range of the carbon number of the hydrocarbon group represented by R 1 include ranges such as 1 or more and 20 or less, 1 or more and 12 or less, and 2 or more and 8 or less.

[0038] R 1Examples of the unsubstituted hydrocarbon group represented by [the formula] include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, isobutyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group; cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group; and aromatic hydrocarbon groups such as phenyl group, 1-naphthyl group, 2-naphthyl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 1-triphenylenyl group, and 2-triphenylenyl group; etc.

[0039] R 1 When the hydrocarbon group represented by [the formula] has a substituent, examples of the substituent include deuterium atom; alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, and tert-butyl group; cycloalkyl groups having 3 to 6 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group; aromatic hydrocarbon groups having 6 to 12 carbon atoms such as phenyl group, 1-naphthyl group, and 2-naphthyl group; oxygen-containing heterocyclic groups such as furanyl group; sulfur-containing heterocyclic groups such as thienyl group; heterocyclic groups such as nitrogen-containing heterocycles including pyrrolyl group and pyridyl group; halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom; isocyanate group; cyano group; amino group; amide group; and nitro group; etc.

[0040] Therefore, when the hydrocarbon group represented by R 1 has a substituent, R 1Examples thereof include aralkyl groups such as benzyl group, phenethyl group, 1-naphthylmethyl group, and 2-naphthylmethyl group; cycloalkylalkyl groups such as cyclohexylmethyl group; hydrocarbon groups having an oxygen-containing heterocycle such as furfuryl group; hydrocarbon groups having a sulfur-containing heterocycle such as thienylmethyl group; and hydrocarbon groups having a nitrogen-containing heterocycle such as pyridylmethyl group; etc. can be preferably mentioned.

[0041] R 1 is preferably an alkyl group, more preferably a methyl group or an ethyl group, and still more preferably an ethyl group.

[0042] In the general formula (I), p is usually an integer of 1 or more and 4 or less, preferably an integer of 2 or more and 4 or less, and more preferably 4.

[0043] Specific examples of the tetravalent zirconium alkoxide represented by the general formula (I) include tetramethoxyzirconium, tetraethoxyzirconium, tetraallyloxide zirconium, tetra-n-propoxide zirconium, tetraisopropoxide zirconium, tetra-n-butoxide zirconium, tetraisobutoxide zirconium, tetra-sec-butoxide zirconium, tetra-tert-butoxide zirconium, tetra-n-pentyloxide zirconium, tetracyclopentyloxide zirconium, tetrahexyloxide zirconium, tetracyclohexyloxide zirconium, tetrabenzyloxide zirconium, tetraoctyloxide zirconium, tetrakis(2-ethylhexyloxy)zirconium, tetradecyloxide zirconium, tetradodecyloxide zirconium, tetrastearyloxide zirconium, tetrakis(8-hydroxyoctyloxy)zirconium, diisopropoxybis(2-ethyl-1,3-hexanediolato)zirconium, bis(2-ethylhexyloxy)bis(2-ethyl-1,3-hexanediolato)zirconium, tetrakis(2-chloroethoxy)zirconium, tetrakis(2-bromoethoxy)zirconium, tetrakis(2-methoxyethoxy)zirconium, tetrakis(2-ethoxyethoxy)zirconium, butoxytrimethoxyzirconium, dibutoxydimethoxyzirconium, butoxy triethoxyzirconium, dibutoxydiethoxyzirconium, butoxy triisopropoxyzirconium, dibutoxydiisopropoxyzirconium, tetraphenoxyzirconium, tetrakis(o-chlorophenoxy)zirconium, tetrakis(m-nitrophenoxy)zirconium, and tetrakis(p-methylphenoxy)zirconium, etc.Among these, examples of the tetravalent zirconium alkoxide include tetramethoxyzirconium, tetraethoxyzirconium, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetraisobutoxyzirconium, tetra-sec-butoxyzirconium, tetra-tert-butoxyzirconium, tetra-n-pentyloxyzirconium, tetrahexyloxyzirconium, tetraoctyloxyzirconium, tetrakis(2-ethylhexyloxy)zirconium, tetradecyloxyzirconium, tetradodecyloxyzirconium, and tetrastearyloxyzirconium, etc. Tetramethoxyzirconium, tetraethoxyzirconium, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetraisobutoxyzirconium, tetra-sec-butoxyzirconium, and tetra-tert-butoxyzirconium, etc. are particularly preferred.

[0044] The carrier may carry a single type of zirconium alkoxide, or two or more zirconium alkoxides may be supported on the metal oxide. When two or more zirconium alkoxides are supported on the metal oxide, the combination and ratio of the zirconium alkoxides are not particularly limited.

[0045] The loading amount of zirconium alkoxide is not particularly limited and may be set according to the use of the zirconium alkoxide-supported metal oxide. However, based on the total amount of the zirconium alkoxide-supported metal oxide (i.e., when the total amount of the zirconium alkoxide-supported metal oxide is 100% by weight), it is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 3% by weight or more, and even more preferably 5% by weight or more. Also, it is preferably 20% by weight or less, more preferably 15% by weight or less, and still more preferably 10% by weight or less. That is, suitable ranges for the loading amount of zirconium alkoxide based on the total amount of the zirconium alkoxide-supported metal oxide include, for example, ranges of 1% by weight or more and 20% by weight or less, 2% by weight or more and 15% by weight or less, 3% by weight or more and 10% by weight or less, and 5% by weight or more and 10% by weight or less.

[0046] The loading amount of zirconium alkoxide is measured by X-ray fluorescence analysis (XRF).

[0047] 1-3. Method for producing zirconium alkoxide-supported metal oxide The method for producing the zirconium alkoxide-supported metal oxide according to this embodiment is not particularly limited, but preferably includes a loading step of loading zirconium alkoxide on a carrier by contacting a solution containing zirconium alkoxide with the carrier and then removing the solvent of the solution.

[0048] The solvent of the zirconium alkoxide solution used in the loading step is not particularly limited as long as it can dissolve zirconium alkoxide and does not dissolve the metal oxide as the carrier. Examples of such solvents include aliphatic hydrocarbon solvents such as n-hexane, n-octane, n-decane, and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, o-xylene, m-xylene, and p-xylene; alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethylene glycol, and diethylene glycol; etc. Preferably, it is an aromatic hydrocarbon solvent, and more preferably toluene.

[0049] The concentration of zirconium alkoxide in the zirconium alkoxide solution is not particularly limited and may be set according to the type of zirconium alkoxide, the supported amount of zirconium alkoxide, etc. Preferably, it is 0.1% by weight or more, more preferably 3% by weight or more, and preferably 50% by weight or less, more preferably 20% by weight or less. That is, the suitable range of the concentration of zirconium alkoxide in the zirconium alkoxide solution includes, for example, the range of 0.1% by weight or more and 50% by weight or less, and 3% by weight or more and 20% by weight or less.

[0050] The method of contacting the metal oxide with the zirconium alkoxide solution in the supporting step is not particularly limited, and examples thereof include a method of mixing the zirconium alkoxide solution and the metal oxide. Further, the method of removing the solvent in the supporting step is not particularly limited, and preferably, for example, a method of distilling off and drying the solvent under reduced pressure conditions can be mentioned.

[0051] 2. Method for producing a carbonic acid diester The second embodiment of the present disclosure is a method for producing a carbonic acid diester including a reaction step of reacting an alkoxysilane and carbon dioxide in the presence of the zirconium alkoxide-supported metal oxide according to the first embodiment of the present disclosure. In this embodiment, since water is not by-produced even when an alkoxysilane and carbon dioxide are reacted, a carbonic acid diester can be obtained without using a dehydrating agent, which is industrially useful. and can be obtained, which is industrially useful.

[0052] In the reaction step, it is presumed that the reaction proceeds by the following mechanism. First, when zirconium alkoxide supported on a metal oxide reacts with carbon dioxide, carbon dioxide is inserted between the bonds of zirconium and alkoxy groups, resulting in a structure represented by Zr - O - (C = O) - OR, thereby activating the carbon dioxide molecule. The site represented by O - (C = O) - OR in this structure, together with the alkoxy group bonded to zirconium, desorbs to produce the target diester carbonate. Subsequently, alkoxysilane donates an alkoxy group to the catalyst molecule after the desorption of the diester carbonate, converting the alkoxysilane to disiloxane and regenerating the catalytically active zirconium alkoxide.

[0053] 2-1. Alkoxysilane The alkoxysilane used in the reaction process is not particularly limited and may be selected according to the diester carbonate as the production target. However, it is preferably at least one selected from the group consisting of the compound represented by the general formula (A1) and the compound represented by the general formula (A2), and more preferably the compound represented by the general formula (A1).

[0054] (R a2 ) 4-n1 Si(OR a1 ) n1 (A1) R a3 [Si(R a2 ) 3-n2 (OR a1 ) n2 m (A2)

[0055] In the general formula (A1), each R a1 is independently a hydrocarbon group which may have a substituent.

[0056] R a1 The number of carbon atoms of the hydrocarbon group which may have a substituent represented by is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and preferably 30 or less, more preferably 24 or less, and even more preferably 12 or less. That is, R a1 ​Suitable ranges for the number of carbon atoms of the hydrocarbon group represented by include, for example, ranges of 1 or more and 30 or less, 1 or more and 24 or less, and 2 or more and 12 or less.

[0057] R a1 Examples of the unsubstituted hydrocarbon group represented by include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, isobutyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and n-icosyl group; cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group; and aromatic hydrocarbon groups such as phenyl group, 1-naphthyl group, 2-naphthyl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 1-triphenylenyl group, and 2-triphenylenyl group; etc.

[0058] R a1 When the hydrocarbon group represented by has a substituent, examples of the substituent include deuterium atom; alkyl groups having 1 or more and 4 or less carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, and tert-butyl group; cycloalkyl groups having 3 or more and 6 or less carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, and cyclohexyl group; aromatic hydrocarbon groups having 6 or more and 12 or less carbon atoms such as phenyl group, 1-naphthyl group, and 2-naphthyl group; oxygen-containing heterocyclic groups such as furanyl group; thienyl Sulfur-containing heterocyclic groups such as a base; heterocyclic groups such as nitrogen-containing heterocycles such as a pyrrolyl group and a pyridyl group; halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; an isocyanate group; a cyano group; an amino group; an amide group; and a nitro group; etc. are mentioned.

[0059] Therefore, when the hydrocarbon group represented by R a1 has a substituent, examples of R a1 include aralkyl groups such as a benzyl group, a phenethyl group, a 1-naphthylmethyl group, and a 2-naphthylmethyl group; cycloalkylalkyl groups such as a cyclohexylmethyl group; hydrocarbon groups having an oxygen-containing heterocycle such as a furfuryl group; hydrocarbon groups having a sulfur-containing heterocycle such as a thienylmethyl group; and hydrocarbon groups having a nitrogen-containing heterocycle such as a pyridylmethyl group; etc. can be preferably mentioned.

[0060] R a1 is preferably an alkyl group, more preferably a methyl group or an ethyl group, and still more preferably an ethyl group, from the viewpoint of reaction efficiency.

[0061] In the general formula (A1), each R a2 independently represents a hydrocarbon group which may have a substituent.

[0062] R a2 The number of carbon atoms of the hydrocarbon group which may have a substituent represented by is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and is preferably 30 or less, more preferably 24 or less, and still more preferably 12 or less. That is, examples of the preferable range of the number of carbon atoms of the hydrocarbon group represented by R a2 include ranges such as 1 to 30, 1 to 24, and 2 to 12.

[0063] R a2 Examples of the unsubstituted hydrocarbon group represented by are those exemplified as the unsubstituted hydrocarbon group represented by R a1 .

[0064] R a2When the hydrocarbon group represented by has a substituent, examples of the substituent include those exemplified as the substituent of the hydrocarbon group represented by R a1 Preferably, it is an isocyanate group or a cyano group. Examples include those exemplified as the substituent of the hydrocarbon group represented by a1 .

[0065] R a2 When the hydrocarbon group represented by has a substituent, examples of R a2 include those exemplified as the hydrocarbon group which may have a substituent represented by R a1 .

[0066] R a2 From the viewpoints of availability and stability, is preferably a methyl group, an ethyl group, a vinyl group, an allyl group, or a phenyl group.

[0067] In the general formula (A1), n1 is usually an integer of 1 or more and 4 or less. From the viewpoint of reaction efficiency, it is preferably an integer of 2 or more and 4 or less, more preferably 3 or 4, and still more preferably 4.

[0068] When n1 is an integer of 2 or more and 4 or less, two OR a1 bonded to the same Si atom a1 of R may be bonded to each other to form a ring. a1 When n1 is an integer of 1 or more and 3 or less, R a1 of the OR a2 group bonded to the same Si atom and R

[0069] Examples of the alkoxysilane represented by the general formula (A1) include monoalkoxysilane, dialkoxysilane, trialkoxysilane, and tetraalkoxysilane.

[0070] Specific examples of monoalkoxysilane include methoxytrimethylsilane, methoxytriethylsilane, methoxytripropylsilane, methoxytrisopropylsilane, methoxytrisobutylsilane, methoxytrioctylsilane, methoxytrishexadecylsilane, methoxytrimethylsilane, meth ethoxytriphenylsilane, phenylmethoxydimethylsilane, phenylmethoxydiethylsilane, ethoxytrimethylsilane, ethoxytriethylsilane, ethoxytripropylsilane, ethoxytriisobutylsilane, ethoxytrioctylsilane, ethoxytriphenylsilane, ethoxytrivinylsilane, ethoxytriallylsilane, ethoxydiethylphenylsilane, phenylethoxydipropylsilane, propoxytrimethylsilane, propoxytriethylsilane, propoxytripropylsilane, phenylpropoxydimethylsilane, phenylpropoxydiethylsilane, and phenylpropoxydipropylsilane.

[0071] Specific examples of dialkoxysilanes include dimethoxydimethylsilane, dimethoxydiethylsilane, dimethoxydipropylsilane, phenyldimethoxymethylsilane, dimethoxymethylvinylsilane, dimethoxydiphenylsilane, diethoxydimethylsilane, diethoxydiethylsilane, diethoxydipropylsilane, diethoxymethylphenylsilane, diethoxyethylphenylsilane, diethoxyphenylpropylsilane, dipropoxydimethylsilane, dipropoxydiethylsilane, dipropoxydipropylsilane, phenyldipropoxymethylsilane, phenyldipropoxyethylsilane, phenyldipropoxypropylsilane, dibutoxydimethylsilane, dibutoxydiethylsilane, and phenyldimethoxyethylsilane.

[0072] Specific examples of the trial alkoxysilane include trimethoxymethylsilane, trimethoxyethylsilane, trimethoxypropylsilane, trimethoxyisobutylsilane, trimethoxyoctylsilane, trimethoxyhexadecylsilane, triethoxymethylsilane, triethoxyethylsilane, triethoxypropylsilane, triethoxyisobutylsilane, triethoxyoctylsilane, trimethoxyvinylsilane, trimethoxyphenylsilane, triethoxyphenylsilane, triethoxyvinylsilane, triethoxyallylsilane, tripropoxymethylsilane, tripropoxyethylsilane, tripropoxypropylsilane, tripropoxyphenylsilane, 2-cyanoethyltriethoxysilane, and 3-(triethoxysilyl)propyl isocyanate, etc.

[0073] Specific examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, and tetrakis(2-ethylhexyloxy)silane, etc.

[0074] In the general formula (A2), R a1 and R a2 are respectively synonymous with R a1 and R a2 in the general formula (A1), and their preferred embodiments are also the same.

[0075] In the general formula (A2), R a3 is each independently a hydrocarbon group which may have a substituent.

[0076] R a3 The number of carbon atoms of the hydrocarbon group which may have a substituent represented by is not particularly limited, but is preferably 1 or more, more preferably 3 or more, still more preferably 6 or more, and is preferably 100 or less, more preferably 50 or less, still more preferably 12 or less. That is, the preferable range of the number of carbon atoms of the hydrocarbon group represented by R a1 is, for example, in the range of 1 or more and 100 or less, 3 or more and 50 or less, and 6 or more and 12 or less.

[0077] R a3 Examples of the unsubstituted hydrocarbon group represented by a3 include groups obtained by removing m hydrogen atoms from alkanes such as methane, ethane, propane, butane, and hexane; groups obtained by removing m hydrogen atoms from cycloalkanes such as cyclohexane and cyclooctane; and groups obtained by removing m hydrogen atoms from aromatic hydrocarbons such as benzene, biphenyl, terphenyl, naphthalene, and anthracene; etc.

[0078] R a3 When the hydrocarbon group represented by a3 has a substituent, examples of the substituent include those exemplified as the substituent of the hydrocarbon group represented by a1 and an alkoxy group, and preferably, an alkoxy group, an isocyanate group, or a cyano group. a1 When the hydrocarbon group represented by a1 has a substituent, examples of the substituent include those exemplified as the substituent of the hydrocarbon group represented by a1 and an alkoxy group, and preferably, an alkoxy group, an isocyanate group, or a cyano group.

[0079] R a3 One or more carbon atoms of the hydrocarbon group represented by a3 may be replaced by Si atoms. R a3 When one or more carbon atoms of the hydrocarbon group represented by a3 are replaced by Si atoms, the Si atom may have a substituent.

[0080] In the general formula (A2), the alkoxysilane moiety represented by -Si(R a2 ) 3-n2 (OR a1 ) n2 may be bonded to the same carbon atom or different carbon atoms among the carbon atoms constituting R a3 .

[0081] In the general formula (A2), n2 is usually an integer of 1 or more and 3 or less, and from the viewpoint of reaction efficiency, it is preferably 2 or 3, and more preferably 3.

[0082] In the general formula (A2), m is usually an integer of 2 or more and 20 or less, and from the viewpoint of easy availability of alkoxysilane, it is preferably an integer of 2 or more and 10 or less, more preferably an integer of 2 or more and 6 or less, and still more preferably an integer of 2 or more and 4 or less.

[0083] When n2 is 2 or 3, two ORs bonded to the same Si atom a1 of R a1 may be bonded to each other to form a ring. When n2 is 1 or 2, an OR bonded to the same Si atom a1 group of R a1 and R a2 may be bonded to each other to form a ring.

[0084] When m in the general formula (A2) is 2, examples of the alkoxysilane represented by the general formula (A2) include alkoxysilanes represented by the general formula (A-22).

[0085] When m in the general formula (A2) is 3, examples of the alkoxysilane represented by the general formula (A2) include alkoxysilanes represented by the general formula (A-23).

[0086]

Chemical formula

[0087] Examples of the alkoxysilane represented by the general formula (A2), that is, an alkoxysilane having a plurality of alkoxysilane sites in the molecule, include, for example, a polyvalent alkoxysilane in which a plurality of alkoxysilyl groups are bonded to carbon atoms constituting an aliphatic hydrocarbon group, a polyvalent alkoxysilane in which a plurality of alkoxysilyl groups are bonded to an aromatic hydrocarbon group, a polyvalent alkoxysilane in which a carbon atom of a hydrocarbon group is substituted with an Si atom and the Si atom has an alkoxy group, and a polyvalent alkoxysilane in which a carbon atom of a hydrocarbon group is substituted with an Si atom.

[0088] Specific examples of the polyvalent alkoxysilane in which a plurality of alkoxysilyl groups are bonded to carbon atoms constituting an aliphatic hydrocarbon group include bis(triethoxysilyl)methane, 1,2-bis(t Examples thereof include remethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1,2-bis(triphenoxysilyl)ethane, 1,3-bis(trimethoxysilyl)propane, 1,3-bis(triethoxysilyl)propane, 1,4-bis(triethoxysilyl)butane, 1,5-bis(triethoxysilyl)pentane, 1,6-bis(triethoxysilyl)hexane, and 1,8-bis(triethoxysilyl)octane, 1,1,2-tris(triethoxysilyl)ethane, etc.

[0089] Specific examples of the polyvalent alkoxysilane in which a plurality of alkoxysilyl groups are bonded to an aromatic hydrocarbon group include 1,2-bis(triethoxysilyl)benzene, 1,3-bis(triethoxysilyl)benzene, 1,4-bis(triethoxysilyl)benzene, 1,2,3-tris(triethoxysilyl)benzene, 1,2,4-tris(triethoxysilyl)benzene, 1,3,5-tris(triethoxysilyl)benzene, and 4,4'-bis(triethoxysilyl)biphenyl, etc.

[0090] Specific examples of the polyvalent alkoxysilane in which a carbon atom of a hydrocarbon group is substituted with an Si atom and the Si atom has an alkoxy group include 1,1,1,3,3,5,5,5-octaethoxy-1,3,5-trisilapentane, etc.

[0091] Specific examples of the polyvalent alkoxysilane in which a carbon atom of a hydrocarbon group is substituted with an Si atom include tris(triethoxysilylethyl)methylsilane, etc.

[0092] Among the above, from the viewpoints of availability and reactivity, the alkoxysilane is preferably a compound represented by the general formula (A1), more preferably one selected from tetramethoxysilane, tetraethoxysilane, diethoxydimethylsilane, ethoxymethyltrimethylsilane, triethoxymethylsilane, triethoxyphenylsilane, triethoxyvinylsilane, triethoxyallylsilane, 2-cyanoethyltriethoxysilane, 3-(triethoxysilyl)propyl isocyanate, 1,2-bis(triethoxysilyl)ethane, and 1,6-bis(triethoxysilyl)hexane, and even more preferably one selected from tetramethoxysilane and tetraethoxysilane.

[0093] Commercially available alkoxysilanes may be used, or alkoxysilanes synthesized by oneself may be used.

[0094] The alkoxysilane may be used alone, or two or more kinds thereof may be used in combination in any combination and ratio.

[0095] 2-2. Carbon Dioxide In the reaction step, carbon dioxide (gas) is used as a raw material for the carbonic acid diester. The carbon dioxide may be prepared as an industrial gas, or may be separated and recovered from the exhaust gas from a factory, a power plant, or the like. The carbon dioxide may be used alone, or may be used in the form of a mixed gas in which carbon dioxide and a gas other than carbon dioxide are mixed within a range not significantly impairing the effects of the present disclosure. However, from the viewpoint of improving reactivity, it is preferable to use carbon dioxide alone. Examples of the gas other than carbon dioxide include inert gases such as nitrogen and argon. Hereinafter, the carbon dioxide gas and the above mixed gas are collectively referred to as "carbon dioxide-containing gas".

[0096] The method for introducing carbon dioxide into the reaction system is not particularly limited, and may be a method of replacing the atmosphere in the reactor with a carbon dioxide-containing gas, or a method of supplying a carbon dioxide-containing gas into the reaction solution by bubbling.

[0097] A method of replacing the atmosphere in a reactor with a carbon dioxide-containing gas is used to introduce carbon dioxide into the reaction system. When introducing, the total pressure P of the carbon dioxide-containing gas t is not particularly limited. From the viewpoint of reaction efficiency, it is preferably 1.0 MPa or more, more preferably 2.0 MPa or more, still more preferably 5.0 MPa or more, and preferably 20.0 MPa or less, more preferably 15.0 MPa or less, still more preferably 10.0 MPa or less. That is, the suitable range of the total pressure P of the carbon dioxide-containing gas t is, for example, in the range of 1.0 MPa or more and 20.0 MPa or less, 2.0 MPa or more and 15.0 MPa or less, and 5.0 MPa or more and 10.0 MPa or less.

[0098] When introducing carbon dioxide into the reaction system by bubbling, the total pressure P of the carbon dioxide-containing gas t is preferably about atmospheric pressure, that is, (0.1 ± 0.05) MPa, from the viewpoint of working efficiency.

[0099] The partial pressure P of carbon dioxide gas in the carbon dioxide-containing gas CO2 is not particularly limited. From the viewpoint of reaction efficiency, it is preferably 0.5 MPa or more, more preferably 1.0 MPa or more, still more preferably 4.0 MPa or more, and preferably 15.0 MPa or less, more preferably 12.0 MPa or less, still more preferably 10.0 MPa or less. That is, the suitable range of the partial pressure P of carbon dioxide gas in the carbon dioxide-containing gas CO2 is, for example, in the range of 0.5 MPa or more and 15.0 MPa or less, 1.0 MPa or more and 12.0 MPa or less, and 4.0 MPa or more and 10.0 MPa or less.

[0100] The ratio (P of the partial pressure P of carbon dioxide gas in the carbon dioxide-containing gas to the total pressure P of the carbon dioxide-containing gas t CO2 (P CO2 / P t) is not particularly limited, but is preferably 0.50 or more, more preferably 0.75 or more, still more preferably 0.90 or more, and is usually 1.00 or less, preferably 0.95 or less. That is, P in the reaction step CO2 / P t The preferred range of is, for example, ranges of 0.50 or more and 1.00 or less, 0.75 or more and 1.00 or less, and 0.90 or more and 0.95 or less.

[0101] Note that the above pressure means absolute pressure. Also, the above "total pressure P of the carbon dioxide-containing gas t " and "partial pressure P of carbon dioxide gas in the carbon dioxide-containing gas CO2 " mean the pressure (25 ° C) at the start of the reaction.

[0102] 2-3. Zirconium alkoxide-supported metal oxide In the reaction step, as a catalyst for the reaction of alkoxysilane and carbon dioxide, the zirconium alkoxide-supported metal oxide according to the first embodiment of the present disclosure is used. Since the zirconium alkoxide-supported metal oxide is usually a heterogeneous catalyst that does not dissolve in the reaction solution, it can be separated and recovered by simple operations such as centrifugation and filtration after the reaction step. In addition, the zirconium alkoxide-supported metal oxide can be reused for the production of diester carbonate after being recovered, so it is a catalyst with a low environmental load.

[0103] The zirconium alkoxide-supported metal oxide may be used alone or in combination of two or more in any combination and ratio.

[0104] In the reaction process, the amount (charged amount) of the zirconium alkoxide-supported metal oxide used may be selected according to the type of alkoxysilane, the type of the zirconium alkoxide-supported metal oxide, etc., and is not particularly limited. However, the amount of zirconium alkoxide relative to the amount of substance of alkoxysilane is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, still more preferably 0.5 mol% or more, and even more preferably 1.0 mol% or more. Also, the amount of zirconium alkoxide relative to the amount of substance of alkoxysilane is preferably 25.0 mol% or less, more preferably 20.0 mol% or less, still more preferably 15.0 mol% or less, and even more preferably 10.0 mol% or less. That is, the suitable range of the amount of the zirconium alkoxide-supported metal oxide used relative to the amount of substance of alkoxysilane includes, for example, ranges of 0.01 mol% or more and 25.0 mol% or less, 0.1 mol% or more and 20.0 mol% or less, 0.5 mol% or more and 15.0 mol% or less, and 1.0 mol% or more and 10.0 mol% or less.

[0105] 2-4. Dialkyl carbonate The dialkyl carbonate produced by the production method according to this embodiment is a dialkyl carbonate having two ester groups selected from the group consisting of an ester group derived from an alkoxy group of alkoxysilane and an ester group derived from an alkoxy group of zirconium alkoxide. The dialkyl carbonate produced by the production method according to this embodiment is not particularly limited and may be determined according to its intended use. Examples of the intended use of the dialkyl carbonate include solvents such as electrolytes, alkylating agents, carbonylating agents, gasoline additives, diesel fuel additives, and raw materials for polymers such as polyurethanes and polycarbonates.

[0106] In the reaction process, it is preferable to use one or more compounds selected from the group consisting of a compound represented by the general formula (A1) and a compound represented by the general formula (A2) as the alkoxysilane. As the zirconium alkoxide-supported metal oxide, it is preferable to use a metal oxide on which a zirconium alkoxide represented by the general formula (I) is supported. Therefore, according to a preferred embodiment of the present embodiment, a mixture of a diester carbonate represented by the general formula (B1), a diester carbonate represented by the general formula (B2), and a diester carbonate represented by the general formula (B3) is produced.

[0107]

Chemical formula

[0108] OR in the general formulas (B1) and (B2) a1 is a group derived from the alkoxy group of the alkoxysilane. That is, R in the general formulas (B1) and (B2) a1 is the same as R in the general formulas (A1) and (A2), and the preferred embodiments thereof are also the same. a1

[0109] OR in the general formulas (B2) and (B3) 1 is a group derived from the alkoxy group of the zirconium alkoxide. That is, R in the general formulas (B2) and (B3) 1 is the same as R in the general formula (I), and the preferred embodiments thereof are also the same. 1 a1

[0110] R a1 and R 1 are preferably the same group in that one kind of diester carbonate can be produced by the production method according to the present embodiment. In other words, the alkoxy group of the alkoxysilane and the alkoxy group of the zirconium alkoxide are preferably the same group.

[0111] Specific examples of the carbonic acid diester represented by any of the general formulas (B1) to (B3) include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, ethyl methyl carbonate, ethyl isopropyl carbonate, dicyclohexyl carbonate, divinyl carbonate, diallyl carbonate, methyl propargyl carbonate, and diphenyl carbonate, and the like.

[0112] 2-5. Reaction solvent In the reaction step, the reaction between the alkoxysilane and carbon dioxide may be carried out in a reaction solvent, or it may be carried out without a solvent, but it is preferably carried out without a solvent.

[0113] In the present disclosure, "without a solvent" means not using a liquid different from the reaction substrate, catalyst, product, and compounds derived therefrom. Therefore, for example, even when the alkoxysilane also acts as a solvent, the alkoxysilane is not regarded as a reaction solvent, and the reaction is regarded as being carried out "without a solvent".

[0114] The type of the reaction solvent is not particularly limited, but a solvent with high solubility of carbon dioxide is preferable in that the carbon dioxide concentration in the reaction system can be increased and the yield of the carbonic acid diester can be improved. Examples of the reaction solvent include aliphatic hydrocarbon solvents such as n - hexane, n - octane, n - decane, and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, o - xylene, m - xylene, and p - xylene; aromatic heterocyclic compound solvents such as pyridine; aprotic polar solvents such as ethyl acetate, N,N - dimethylformamide, dimethylacetamide, dimethyl sulfoxide, 1,3 - dimethyl - 2 - imidazolidinone, and N - methylpyrrolidone (NMP); ether solvents such as diethyl ether, diisopropyl ether, 1,2 - dimethoxyethane, tetrahydrofuran (THF), and dioxane; nitrile solvents such as acetonitrile, propionitrile, butyronitrile, benzonitrile, and 2 - cyanopyridine; and ketone solvents such as acetone and isopropyl ketone; and the like.

[0115] Among these, the reaction solvent is preferably at least one solvent selected from the group consisting of acetonitrile, N,N - dimethylformamide, tetrahydrofuran, toluene, pyridine, 2 - cyanopyridine, and benzonitrile in terms of improving the reaction efficiency.

[0116] The reaction solvent may be used alone or in combination of two or more in any combination and ratio.

[0117] The amount of the reaction solvent used is not particularly limited, but is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, and preferably 200 parts by weight or less, more preferably 100 parts by weight or less, based on 100 parts by weight of the alkoxysilane. That is, suitable ranges for the amount of the reaction solvent used relative to 100 parts by weight of the alkoxysilane include, for example, ranges of 10 parts by weight or more and 200 parts by weight or less, and 20 parts by weight or more and 100 parts by weight or less.

[0118] 2 - 6. Reaction Temperature The reaction temperature in the reaction process is not particularly limited. Preferably, it is 80 °C or higher, more preferably 100 °C or higher, still more preferably 120 °C or higher, and even more preferably 150 °C or higher. Also, preferably, it is 250 °C or lower, more preferably 230 °C or lower, still more preferably 210 °C or lower, and even more preferably 190 °C or lower. That is, examples of the suitable range of the reaction temperature include ranges such as 80 °C or higher and 250 °C or lower, 100 °C or higher and 230 °C or lower, 120 °C or higher and 210 °C or lower, and 150 °C or higher and 190 °C or lower.

[0119] 2-7. Reaction time The reaction time in the reaction process is not particularly limited and may be adjusted according to the reaction temperature, the amount of catalyst, the reaction scale, etc. Specifically, the reaction time is preferably 0.5 hours or longer, more preferably 1 hour or longer, still more preferably 5 hours or longer, and even more preferably 10 hours or longer. Also, preferably, it is 100 hours or shorter, more preferably 72 hours or shorter, still more preferably 48 hours or shorter, and even more preferably 24 hours or shorter. That is, examples of the suitable range of the reaction time include ranges such as 0.5 hours or longer and 100 hours or shorter, 1 hour or longer and 72 hours or shorter, 5 hours or longer and 48 hours or shorter, and 10 hours or longer and 24 hours or shorter.

[0120] 2-8. Reactor The reaction apparatus used in the reaction process is not particularly limited as long as it is formed of a material stable to the raw materials, the catalyst, and the product, and may be selected according to the method of introducing the carbon dioxide-containing gas into the reaction system.

[0121] When the introduction of the carbon dioxide-containing gas into the reaction system is carried out by replacing the atmosphere in the reactor, the reactor is preferably a closed-type reactor (sealed reactor), more preferably a closed-type pressure-resistant reactor, and even more preferably a stainless steel autoclave. When the introduction of carbon dioxide into the reaction system is carried out by bubbling, the reactor preferably has a supply pipe for supplying carbon dioxide to the reaction system by bubbling and a discharge pipe for discharging the gas in the reactor.

[0122] The reactor preferably has a volume that is 10 times or more and 100 times or less the volume of the reaction solution containing alkoxysilane, zirconium alkoxide-supported metal oxide, and, if necessary, a reaction solvent. The reactor may be provided with a magnetic stirrer or a stirring blade for stirring the reaction solution.

[0123] 3. Other steps The production method according to this embodiment may include any arbitrary step in addition to the reaction step. Examples of arbitrary steps include a purification step for increasing the purity of the carbonic ester; and a catalyst recovery step for recovering the zirconium alkoxide-supported metal oxide from the reaction system after the reaction step; and the like.

[0124] As a purification method of the diester carbonate in the purification step, purification methods commonly performed in the field of organic synthesis such as filtration, adsorption, column chromatography, distillation, etc. can be adopted. Specifically, methods such as filtering the obtained solid under a nitrogen atmosphere, washing with diethyl ether or the like, and vacuum drying can be mentioned.

[0125] The recovery of the zirconium alkoxide-supported metal oxide in the catalyst recovery step can be performed by solid-liquid separation of the reaction mixture obtained in the reaction step. The method of solid-liquid separation is not particularly limited, and any method such as centrifugation and filtration can be adopted.

[0126] When the recovered zirconium alkoxide-supported metal oxide is reused in the reaction of alkoxysilane and carbon dioxide, it is preferable to wash and dry the zirconium alkoxide-supported metal oxide separated from the reaction mixture.

[0127] An organic solvent can be preferably used for washing the zirconium alkoxide-supported metal oxide. The organic solvent is not particularly limited, but alcohols such as methanol and ethanol; aliphatic hydrocarbons such as normal hexane and cyclohexane; aromatic hydrocarbons such as toluene; etc. are preferably mentioned. Among these, alcohol is preferable as the organic solvent.

Examples

[0128] Examples are given below to explain the present disclosure in more detail, but it can be appropriately changed as long as it does not deviate from the gist of the present disclosure. Therefore, the scope of the present disclosure should not be construed as being limited by the specific examples shown below. In the present disclosure, "room temperature" means a temperature condition without artificial heating or cooling, specifically, a temperature range of 20°C to 30°C.

[0129] <Reactor> · Equipment: Chemist Plaza Chemi Chemi-300 (manufactured by Shibata Scientific Technology Co., Ltd.) · Rotation speed: 1200 rpm <Gas chromatography (GC) measurement> · Equipment: GC-2014 (manufactured by Shimadzu Corporation) · Detector: FID (hydrogen flame ionization detector) · Column: TC-1 (manufactured by GL Sciences Inc.) · Carrier gas: N2 · Internal standard substance: Mesitylene · Data processing: Lab solutions (manufactured by Shimadzu Corporation)

[0130] <Pretreatment and adjustment of metal oxides> · Silica: Silica (Fuji Silysia Chemical Ltd. "CARiACT Q-10") was calcined in an electric furnace at 300°C for 2 hours. · Cerium oxide nanopowder: Cerium(IV) oxide nanopowder (manufactured by Sigma-Aldrich; average particle size 25 nm) was calcined in an electric furnace at 600°C for 3 hours. · Titania: Titanium(IV) oxide anatase type (manufactured by Fujifilm Wako Pure Chemical Corporation) was calcined in an electric furnace at 600°C for 3 hours. · Cerium: An aqueous solution of cerium(III) nitrate hexahydrate (manufactured by Fujifilm Wako Pure Chemical Corporation) was dried in an air atmosphere and calcined in an electric furnace at 600°C for 3 hours to prepare cerium.

[0131] <Example 1-1: Preparation of Zirconium Alkoxide-Supported Metal Oxide> Toluene was added to zirconium tetraethoxide and heated under reflux to prepare a zirconium tetraethoxide solution. This solution was mixed with ceria prepared from cerium nitrate at room temperature. At this time, the solution and ceria were mixed such that the amount of zirconium tetraethoxide relative to 95 parts by weight of ceria was 5 parts by weight. From the obtained mixture, toluene was distilled off at 40 °C under reduced pressure and dried to obtain a zirconium alkoxide-supported metal oxide.

[0132] <Examples 1-2 to 1-6: Preparation of Zirconium Alkoxide-Supported Metal Oxide> A zirconium alkoxide-supported metal oxide was obtained in the same manner as in Example 1-1, except that the carrier was changed to those shown in Table 1.

[0133] <Example 1-7: Preparation of Zirconium Alkoxide-Supported Metal Oxide> (Preparation of Core-Shell Type Particles) An aqueous solution of cerium(III) nitrate hexahydrate (manufactured by Fujifilm Wako Pure Chemical Corporation) was added to silica such that the content of ceria relative to the total amount of the core-shell type particles after firing was 5% by weight, dried at 120 °C in an air atmosphere, and then fired at 600 °C for 3 hours to obtain core-shell type particles.

[0134] (Supporting of Zirconium Alkoxide) Toluene was added to zirconium tetraethoxide and heated under reflux to prepare a zirconium tetraethoxide solution. This solution was mixed with the core-shell type particles at room temperature. At this time, the solution and the core-shell type particles were mixed such that the amount of zirconium tetraethoxide relative to 95 parts by weight of the core-shell type particles was 5 parts by weight. From the obtained mixture, toluene was distilled off at 40 °C under reduced pressure and dried to obtain a zirconium alkoxide-supported metal oxide.

[0135] <Examples 1-8 to 1-11: Preparation of Zirconium Alkoxide-Supported Metal Oxide> In the preparation of the core-shell type particles, the mixing ratio of silica and the aqueous solution of cerium nitrate was changed so that the content of ceria relative to the total amount of the core-shell type particles after firing was as shown in Table 1. The same procedure as in Example 1-7 was repeated to obtain a zirconium alkoxide-supported metal oxide. Ta.

[0136] <Example 1-12: Preparation of zirconium alkoxide-supported metal oxide> A zirconium alkoxide-supported metal oxide was obtained in the same manner as in Example 1-11, except that in the preparation of core-shell type particles, silica was changed to titania.

[0137] [Table 1]

[0138] <Example 2-1: Production of carbonic acid diester> [ka]

[0139] In a nitrogen-filled groove box, 2.0 g of the zirconium alkoxide-supported metal oxide obtained in Example 1-2 and 3.5 mL of tetraethoxysilane (TEOS) were added to a 10 mL SUS autoclave (manufactured by Taiatsu Glass Industry Co., Ltd.) containing a magnetic stirrer. Carbon dioxide gas was charged into the autoclave at 25°C so that the charging pressure inside the autoclave was 5.0 MPa, and the autoclave was maintained for 10 minutes. The reaction solution was then heated to 220°C with stirring and reacted for 6 hours to produce diethyl carbonate.

[0140] After the reaction, the autoclave was cooled to room temperature and the remaining gas was released. Mesitylene was added to the reaction mixture as an internal standard, and a portion of the supernatant was collected and analyzed by GC to determine the yield of diethyl carbonate relative to TEOS. The yield of diethyl carbonate is shown in Table 2.

[0141] <Example 2-2 to 2-5: Production of Carbonate Diesters> Diethyl carbonate was produced in the same manner as in Example 2-1, except that the type and amount of the metal oxide supported on zirconium alkoxide were changed as shown in Table 2. The yield of diethyl carbonate is shown in Table 2.

[0142] <Comparative Example 2-1: Production of Carbonate Diesters> Diethyl carbonate was produced in the same manner as in Example 2-1, except that 0.1 g of zirconium tetraethoxide was used instead of 2.0 g of the metal oxide supported on zirconium alkoxide. The yield of diethyl carbonate is shown in Table 2. Note that zirconium tetraethoxide is a homogeneous catalyst, not a heterogeneous catalyst, and thus it is a catalyst that is difficult to recover after the reaction.

[0143] <Comparative Example 2-2: Production of Carbonate Diesters> Diethyl carbonate was produced in the same manner as in Example 2-1, except that 0.3 g of ceria nanopowder was used instead of 2.0 g of the metal oxide supported on zirconium alkoxide. The yield of diethyl carbonate is shown in Table 2.

[0144]

Table 2

[0145] <Example 3-1: Production of Carbonate Diesters>

Chemical formula

[0146] In a nitrogen-filled groove box, 1.0 g of the zirconium alkoxide-supported metal oxide obtained in Example 1-1 and 3.27 mL of tetraethoxysilane (TEOS) were added to a 10 mL SUS autoclave (manufactured by Taiatsu Glass Industry Co., Ltd.) containing a magnetic stirrer. Carbon dioxide gas was charged into the autoclave at 25°C so that the charging pressure inside the autoclave was 5.0 MPa, and the autoclave was maintained for 10 minutes. The reaction solution was then heated to 180°C with stirring and reacted for 15 hours to produce diethyl carbonate.

[0147] After the reaction, the autoclave was cooled to room temperature and the remaining gas was released. Mesitylene was added to the reaction mixture as an internal standard, and a portion of the supernatant was collected and analyzed by GC to determine the yield of diethyl carbonate relative to TEOS. The yield of diethyl carbonate is shown in Table 3.

[0148] <Examples 3-2 to 3-9: Production of Carbonate Diesters> Diethyl carbonate was produced in the same manner as in Example 3-1, except that the zirconium alkoxide-supported metal oxide was changed to one shown in Table 3. The yield of diethyl carbonate is shown in Table 3.

[0149] <Comparative Example 3-1: Production of Carbonate Diester> Diethyl carbonate was produced in the same manner as in Example 3-1, except that the core-shell particles prepared in Example 1-7 were used instead of the zirconium alkoxide-supported metal oxide. The yield of diethyl carbonate is shown in Table 3.

[0150] <Comparative Example 3-2: Production of Carbonate Diester> Instead of 1.0 g of zirconium alkoxide-supported metal oxide, zirconium tetraethoxylate Diethyl carbonate was produced in the same manner as in Example 3-1, except that 0.05 g of methyl methyl ether was used. The yield of diethyl carbonate is shown in Table 3. Note that zirconium tetraethoxide is a homogeneous catalyst, not a heterogeneous catalyst, and thus it is a catalyst that is difficult to recover after the reaction.

[0151]

Table 3

[0152] <Example 4-1: Evaluation of Catalyst Recyclability> After producing diethyl carbonate in the same procedure as in Example 3-1 using the zirconium alkoxide-supported metal oxide obtained in Examples 1-6, the suspension remaining in the autoclave was washed into a centrifuge tube with TEOS, and the supernatant was removed by centrifugation. TEOS was added to the residue, and after stirring, the operations of centrifugation and removal of the supernatant were repeated until mesitylene, which is an internal standard substance, was no longer detected by GC in the supernatant. Thereafter, the zirconium alkoxide-supported metal oxide was washed and recovered.

[0153] Using the recovered zirconium alkoxide-supported metal oxide, diethyl carbonate was produced again in the same procedure as in Example 3-1. Thereafter, by repeating the recovery of the zirconium alkoxide-supported metal oxide and the subsequent production of dialkyl carbonate, the change in the catalytic activity of the zirconium alkoxide-supported metal oxide due to reuse was evaluated. The results are shown in Fig. 1.

[0154] <Examples 4-2 to 4-8: Evaluation of Catalyst Recyclability> The change in the catalytic activity of the zirconium alkoxide-supported metal oxide due to reuse was evaluated in the same manner as in Example 4-1, except that the zirconium alkoxide-supported metal oxide shown in Table 4 was used. The results are shown in Fig. 1.

[0155]

Table 4

Industrial Applicability

[0156] According to the present disclosure, a novel zirconium alkoxide-supported metal oxide can be provided. This zirconium alkoxide-supported metal oxide can be used as a heterogeneous catalyst in organic synthesis reactions.

Claims

Claim 1 A zirconium alkoxide supported metal oxide comprising a carrier and a zirconium alkoxide supported on the carrier, wherein the carrier is a metal oxide. Claim 2 The zirconium alkoxide supported metal oxide according to claim 1, wherein the zirconium alkoxide is a compound represented by the general formula (I). (R １ ) ４－ｐ Zr(OR １ ) ｐ (I) (R １ is, independently of one another, a hydrocarbon group which may have a substituent; p is an integer of 1 or more and 4 or less.) Claim 3 The zirconium alkoxide supported metal oxide according to claim 1, wherein the metal oxide contains an oxide of one or more metals selected from the group consisting of rare earth metals, Group 4 metals of the periodic table, Group 13 metals of the periodic table, and Group 14 metals of the periodic table. Claim 4 The zirconium alkoxide supported metal oxide according to claim 1, wherein the carrier is a core-shell type particle. Claim 5 The zirconium alkoxide supported metal oxide according to claim 4, wherein the core of the core-shell type particle is silica and the shell of the core-shell type particle is ceria. Claim 6 The zirconium alkoxide supported metal oxide according to claim 4, wherein the content of the core with respect to the total amount of the core-shell type particles is 10% by weight or more and 99% by weight or less, and the content of the shell with respect to the total amount of the core-shell type particles is 1% by weight or more and 90% by weight or less. Claim 7 The zirconium alkoxide supported metal oxide according to claim 1, wherein the supported amount of the zirconium alkoxide is 1% by weight or more and 20% by weight or less with respect to the total amount of the zirconium alkoxide supported metal oxide. Claim 8 The zirconium alkoxide supported metal oxide according to claim 1, which is a catalyst used in the reaction for synthesizing a diester carbonate from an alkoxysilane and carbon dioxide. Claim 9 A method for producing a zirconium alkoxide supported metal oxide, comprising a supporting step of supporting the zirconium alkoxide on the carrier by removing the solvent of the solution after bringing a solution containing the zirconium alkoxide into contact with the carrier, wherein the carrier is a metal oxide. Claim 10 The method for producing a zirconium alkoxide supported metal oxide according to claim 9, wherein the zirconium alkoxide is a compound represented by the general formula (I). (R １ ) ４－ｐ Zr(OR １ ) ｐ (I) (R １ is, independently of one another, a hydrocarbon group which may have a substituent; p is an integer of 1 or more and 4 or less.) Claim 11 The method for producing a zirconium alkoxide supported metal oxide according to claim 9, wherein the metal oxide contains an oxide of one or more metals selected from the group consisting of rare earth metals, Group 4 metals of the periodic table, Group 13 metals of the periodic table, and Group 14 metals of the periodic table. Claim 12 The method for producing a zirconium alkoxide-supported metal oxide according to claim 9, wherein the carrier is a core-shell type particle.

13. The method for producing a zirconium alkoxide-supported metal oxide according to claim 12, wherein the core of the core-shell type particle is silica and the shell of the core-shell type particle is ceria.

14. A method for producing a diester carbonate, comprising a reaction step of reacting an alkoxysilane with carbon dioxide in the presence of the zirconium alkoxide-supported metal oxide according to any one of claims 1 to 8.

15. The method for producing a diester carbonate according to claim 14, wherein the alkoxysilane is at least one selected from the group consisting of a compound represented by the general formula (A1) and a compound represented by the general formula (A2). (R ａ２ ) ４－ｎ１ Si(OR ａ１ ) ｎ１ (A1) R ａ３ [Si(R ａ２ ) ３－ｎ２ (OR １ ) ｎ２ ｍ (A2)​ (R ａ１ are each independently a hydrocarbon group which may have a substituent; R ａ２ are each independently a hydrocarbon group which may have a substituent; R ａ３ are each independently a hydrocarbon group which may have a substituent; n1 is an integer of 1 or more and 4 or less; n2 is an integer of 1 or more and 3 or less; m is an integer of 2 or more and 20 or less; when n1 is an integer of 2 or more and 4 or less, two OR ａ１ R ａ１ may be bonded to each other to form a ring; when n1 is an integer of 1 or more and 3 or less, OR ａ１ R in the group ａ１ and R ａ２ may be bonded to each other to form a ring; when n2 is 2 or 3, two OR ａ１ R ａ１ may be bonded to each other to form a ring; when n2 is 1 or 2, OR ａ１ R in the group ａ１ and R ａ２ may be bonded to each other to form a ring.)

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