JP2012052012A - Catalyst, and process for producing polymer using the catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst which limits the reaction field in performing the catalytic reaction to the inner part of a pore of mesoporous silica to allow the catalytic reaction to proceed by selectively modifying the external surface of a pore wall of the mesoporous silica with an organic group and selectively introducing an active species of catalyst onto the inner surface of the pore wall.SOLUTION: The catalyst is obtained by selectively modifying the outer surface of a pore wall with an organic substance to control the catalytic reaction in the mesoporous silica having a pore and the pore wall forming the pore on the one hand and selectively fixing an active species of catalyst onto the inner surface of the pore wall on the other hand.

Description

  The present invention relates to a catalyst and a method for producing a polymer using the catalyst, and more particularly to a catalyst using mesoporous silica.

The inventors of the present invention have been researching the use of mesoporous silica and have applied for a patent (Patent Document 1). Mesoporous silica has a regular pore structure with a large specific surface area, and is widely used as a support for metal catalysts. There has been reported an attempt to use a special catalytic reaction field after introducing an active metal species into a regular mesoporous space of mesoporous silica to form a catalyst (Patent Document 2).
However, in the reports so far, it has been difficult to strictly control the reaction field because catalytic active sites exist on the entire surface of mesoporous silica.

JP 2009-061372 A JP 2005-336457 A

  The present invention has been made in view of the above circumstances, and the outer surface of the pore wall of mesoporous silica is selectively modified with an organic group (see FIG. 1: F. D, Juan, E. Ruiz-Hitzky). , Adv. Mater., 12, 430 (2000)), by introducing catalytically active species selectively on the inner surface, the reaction field during catalytic reaction is limited to the inside of the pores of mesoporous silica. It is to provide a catalyst that can be performed.

The catalyst according to the present invention for achieving the above object is a mesoporous silica having pores and pore walls forming the pores, and the outer surface of the pore walls is selected to regulate the catalytic reaction. While being modified by organic substances, catalytically active species are selectively fixed on the inner surface of the pore wall.
In the present invention, the average diameter of the pores is preferably 1 nm to 20 nm.
The catalytically active species is preferably copper.
Moreover, it is preferable that the said catalyst is a thing used for the oxidative polymerization reaction of a phenol compound.
The method for producing a polymer according to the present invention is characterized in that a phenol compound is oxidatively polymerized using the catalyst described above.

Further, in the method for producing the catalyst according to the present invention, the reaction mixture obtained by mixing the surfactant and the skeleton component is subjected to a condensation polymerization reaction, and the pores defined by the pore walls formed by the skeleton component are contained in the pores. After creating the mesoporous silica precursor filled with the surfactant, the outer surface of the mesoporous silica precursor is selectively modified with an organic reagent that modifies the hydroxyl group on the outer surface of the pore wall, After obtaining the mesoporous silica whose outer surface is modified with an organic group by removing the surfactant in the pores, a catalytically active species is selectively fixed on the inner surface of the pore wall. .
In the present invention, the mesoporous silica means a substance having uniform and regular pores (mesopores: about 1 nm to 50 nm in diameter) made of silica (silicon dioxide) as a catalyst / adsorption material. Applied research is being conducted.
The organic substance means a substance for preventing the catalyst from being bonded by bonding to a hydroxyl group on the surface of silica.
An organic reagent means a reagent for regulating fixation of a catalytically active species by binding to a hydroxyl group on the outer surface of a pore wall. As such an organic reagent, for example, a silylating reagent (silylating agent) can be used.
By catalytically active species is meant a substance that is essentially catalytic. When the predetermined metal is a catalytically active species, in addition to the case where only the metal is fixed to the inner surface of the pore wall, the case where the organometallic catalyst containing the metal is fixed is included.

  According to the present invention, since the catalytic reaction is selectively performed in the internal space of the pores provided in the mesoporous silica, particularly when a polymer is produced by performing a polymerization reaction, compared to a polymer using a conventional catalyst. It is possible to produce a polymer having a lower molecular weight and a narrower molecular weight distribution.

It is a figure which shows typically a mode when the surface of mesoporous silica is modified with the organic group. (A) is a figure which shows a mode that the outer inner surface of a pore wall is modified with the organic group, (b) shows a mode that the outer surface of the pore wall is selectively modified with the organic group. FIG. It is an image figure when a silane coupling agent couple | bonds with the surface of mesoporous silica. (A) is a figure which shows a mode that a silane coupling agent self-polymerizes, (b) is a figure which shows a mode that it fixes as a monomolecular layer. Results of measurement of pore diameters when various silylating agents were reacted with MCM during production by BJH method (EP Barrett, LG Joyner, PP Halenda: J. Amer. Chem. Soc. 73, 373 (1951)) It is a graph which shows. (A) shows the result of trimethylsilyl trifluoromethanesulfonate, (b) shows the result of 1,1-bis (trimethylsiloxy) -1-propene, and (c) shows 1,1,1,3,3,3- The result of hexamethyldisilazane, (d) shows the result of triethoxymethylsilane, (e) shows the result of trimethylchlorosilane, and (f) shows the result of unmodified MCM-41 during production. . It is a graph which shows the molecular weight distribution of a polymer when 2,6-dimethylphenol is polymerized using various catalysts. (A) shows the results of Cu / TMS-MCM (selectively silylated on the outer surface of the pore wall and copper is selectively fixed on the inner surface), and (b) shows the results of Cu / MCM (inner and outer pore walls). (C) shows the results of Cu (OAc) ₂ (copper acetate only).

Next, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited by these embodiments, and various forms are possible without changing the gist of the invention. Can be implemented. Further, the technical scope of the present invention extends to an equivalent range.
Mesoporous silica has an inorganic skeleton, and this inorganic skeleton is composed of a polymer main chain of an inorganic oxide such as silicate. The atoms that replace silicon atoms in the silicate basic skeleton, or the atoms that are added to the silicate skeleton include aluminum, titanium, magnesium, zirconium, tantalum, niobium, molybdenum, cobalt, nickel, gallium, beryllium, yttrium, lanthanum, hafnium, tin , Lead, vanadium, boron and the like.
Other inorganic skeletons that can constitute mesoporous silica include non-Si-based inorganic oxides such as zirconia, titania, niobium oxide, tantalum oxide, tungsten oxide, tin oxide, hafnium oxide, and alumina, or inorganic oxides thereof. A complex oxide in which an atom added to the silicate skeleton is incorporated in the basic skeleton consisting of

Examples of the inorganic backbone components of the mesoporous silica can be used tetramethoxysilane, tetraethoxysilane, alkoxysilane, such as tetra propoxy silane, sodium silicate, kanemite _{(kanemite, NaHSi 2 O 5 ·} 3H 2 O) or silica . These skeletal components form a silicate skeleton.
Mesoporous silica can be obtained by condensation polymerization using a surfactant as a template, and then removing the surfactant. The surfactant used as a template for forming mesoporous silica may be any of cationic, anionic, and nonionic. Specifically, alkyltrimethylammonium (preferably alkyltrimethylammonium) Alkyltrimethylammonium having 8 to 18 carbon atoms), alkylammonium, dialkyldimethylammonium, benzylammonium chloride, bromide, iodide or hydroxide, fatty acid salt, alkylsulfonate, alkylphosphate , Polyethylene oxide nonionic surfactants, primary alkylamines and the like.

Among the surfactants, examples of the polyethylene oxide nonionic surfactant include a polyethylene oxide nonionic surfactant having a hydrocarbon group as a hydrophobic component and polyethylene oxide as a hydrophilic portion. Specific examples of such a surfactant include C ₁₆ H ₃₃ (OCH ₂ CH ₂ ) ₂ OH (hereinafter, such a structure is abbreviated as C ₁₆ EO ₂ ), C ₁₂ EO ₄ , C ₁₆ EO ₁₀ , C ₁₆ EO ₂₀ , C ₁₈ EO ₁₀ , C ₁₈ EO ₂₀ , C ₁₈ H ₃₅ EO _{10 and the} like. Further, esters of fatty acids such as oleic acid, lauric acid, stearic acid, palmitic acid and sorbitan, or compounds obtained by adding polyethylene oxide to these esters can be used. Such surfactants include Triton X-100 (Aldrich), polyethylene oxide (20) sorbitan monolaurate (Tween 20, Aldrich), polyethylene oxide (20) sorbitan monopalmitate (Tween 40), polyethylene oxide ( 20) Sorbitan monostearate, polyethylene oxide (20) sorbitan monooleate (Tween 60), sorbitan monopalmitate and the like. One of the above surfactants may be used alone, or two or more may be used in combination.

Furthermore, a polyalkylene oxide of a triblock copolymer type can be used. Among them, a polyethylene oxide chain-polypropylene oxide chain-polyethylene oxide chain type or a polypropylene oxide chain-polyethylene oxide chain-polypropylene oxide chain type triblock copolymer is preferred. used. Here, when a triblock copolymer of ethylene oxide chain-polypropylene oxide chain-polyethylene oxide chain type is represented as (EO) _x (PO) _y (EO) _x , the number of units of each alkylene oxide is preferably x = 5 to 110, y = 15 to 70, more preferably x = 15 to 20, and y = 50 to 60. On the other hand, when a triblock copolymer of polypropylene oxide chain-polyethylene oxide chain-polypropylene oxide chain type is represented as (PO) _x (EO) _y (PO) _x , the number of units of each alkylene oxide is preferably x = 5 to 110. , Y = 15 to 70, more preferably x = 15 to 20 and y = 50 to 60. Specific examples of such triblock copolymers include (EO) ₅ (PO) ₇₀ (EO) ₅ , (EO) ₁₃ (PO) ₃₀ (EO) ₁₃ , (EO) ₂₀ (PO) ₃₀ (EO ) ₂₀ , (EO) ₂₆ (PO) ₃₉ (EO) ₂₆ , (EO) ₁₇ (PO) ₅₆ (EO) ₁₇ , (EO) ₁₇ (PO) ₅₈ (EO) ₁₇ , (EO) ₂₀ (PO) ₇₀ (EO) ₂₀ , (EO) ₈₀ (PO) ₃₀ (EO) ₈₀ , (EO) ₁₀₆ (PO) ₇₀ (EO) ₁₀₆ , (EO) ₁₀₀ (PO) ₃₉ (EO) ₁₀₀ , (EO) ₁₉ (PO ₃₃ (EO) ₁₉ , (EO) ₂₆ (PO) ₃₉ (EO) _26, etc., and these triblock copolymers are commercially available from BASF etc. It is also possible to obtain one having an x value and a y value. Further, these triblock copolymers may be used alone or in combination of two or more.

Furthermore, a star diblock copolymer in which two polyethylene oxide chains-polypropylene oxide chains are bonded to two nitrogen atoms of ethylenediamine can be used as a template. Specific examples of such star diblock copolymers include {(EO) ₁₁₃ (PO) ₂₂ } ₂ NCH ₂ CH ₂ N {(PO) ₂₂ (EO) ₁₁₃ } ₂ , {(EO) ₃ (PO _{) 18} 2 NCH 2 CH 2} N {(PO) 18 (EO) 3} 2, {(PO) 19 (EO) 16} 2 NCH 2 CH 2 N {(EO) 16 (PO) 19} 2 etc. Can be mentioned. In the present invention, one of the above star diblock copolymers may be used alone, or two or more may be used in combination.
When the skeleton component is subjected to polycondensation using the surfactant, water, an organic solvent, a mixture of water and an organic solvent, or the like can be used as a solvent. Further, the molar ratio of the skeletal component and the surfactant used in the reaction (skeleton component / surfactant ratio) is preferably 60 or more, more preferably 90 or more, and still more preferably 120 or more. When the skeletal component / surfactant ratio is within the above range, the mesoporous silica pore diameter obtained tends to be small, the pore wall thickness is increased, and the pore volume tends to be small.

  The method for mixing the above components is not particularly limited, but it is preferable to add a skeletal component after mixing a surfactant with a solvent and simultaneously or subsequently adding an acid to obtain a preferable acidity. Here, the temperature at which the surfactant and the acid are mixed is not particularly limited, but is preferably 0 ° C to 100 ° C. The temperature at which the skeleton component is added is not particularly limited, but is preferably 35 ° C to 80 ° C, and more preferably 40 ° C to 45 ° C. Furthermore, when adding the skeletal component, the entire skeletal component may be added all at once, or the mixed solution may be added in small portions while stirring, but it should be added in small portions over 1 minute while stirring. Is preferred.

  After mixing each component according to the above procedure, a condensation polymerization reaction is performed while maintaining the reaction mixture at a predetermined temperature to obtain a mesoporous silica precursor (with the surfactant still filled in the pores). be able to. Here, the reaction temperature of the polycondensation reaction varies depending on the type and concentration of the surfactant and the skeleton component to be used, but is usually 0 ° C. to 100 ° C., preferably 35 ° C. to 80 ° C. In particular, when the above triblock copolymer is used as a surfactant, the reaction temperature is preferably 40 ° C to 45 ° C. When the reaction temperature of the polycondensation reaction is within the above range, the regularity of the structure of the obtained mesoporous silica tends to be high. In the polycondensation reaction, the reaction temperature can be appropriately changed according to the progress of the reaction.

  In addition, the reaction time of the above condensation polymerization reaction is usually 8 hours to 24 hours, although it varies depending on the type and concentration of the surfactant and the skeleton component to be used. The polycondensation reaction may be performed either in a stationary state or in a stirring state, or may be performed in combination. Further, in the above condensation polymerization reaction, the pore diameter of the obtained mesoporous silica can be controlled by adding a hydrophobic compound such as trimethylbenzene or triisopropylbenzene in addition to the surfactant.

The method of selectively modifying the outer surface of the pore wall with an organic substance is possible even after the formation of mesoporous silica, but if it is performed in the state of a mesoporous silica precursor, it depends on the surfactant remaining in the pores. This is preferable because organic substances prevent modification of the inner surface of the pore wall. Therefore, it is preferable that the outer surface of the pore wall is selectively modified with an organic substance in the mesoporous silica precursor obtained after the condensation polymerization reaction.
When a silyl group is selected as the organic substance, the following operation is performed. By reacting the mesoporous silica precursor with a silylating reagent, the hydroxyl group on the outer surface of the pore wall is silylated. Examples of silylating reagents include trimethylsilyl trifluoromethanesulfonate (Me ₃ SiOSO ₂ CF ₃ ), 1,1-bis (trimethylsiloxy) -1-propene (1,1-bis (trimethyl-silyloxy) -1-propene), 1,1,1,3,3,3-hexamethyldisilazane (1,1,1,3,3,3-hexamethyldisilazane), triethoxymethylsilane, trimethylchlorosilane (Me ₃ SiCl) It is done.

  Mesoporous silica can be obtained by selectively modifying the outer surface of the pore wall with an organic substance and then removing the surfactant in the pore. The surfactant can be removed from the mesoporous silica precursor by a method of treating with a solvent such as water or alcohol.

  When using the method of treating with a solvent, the mesoporous silica is obtained by dispersing the mesoporous silica precursor in a solvent having a high solubility in the surfactant contained in the mesoporous silica precursor and collecting the solid content after stirring. be able to. Here, although there is no restriction | limiting in particular as a solvent used for removal of surfactant, Preferably hydrophilic organic solvents, such as methanol, ethanol, and acetone, are mentioned. In order to sufficiently obtain the extraction efficiency of the surfactant, it is preferable to add a small amount (preferably 0.1 mol / l to 10 mol / l) of hydrochloric acid, nitric acid or the like. The organic solvent can be used even when water is added. The dispersion amount of the mesoporous silica precursor is preferably 0.5 g to 50 g with respect to 100 ml of the solvent.

  Next, an active catalyst species is fixed to the inner surface of the pore wall of the mesoporous silica. Although it does not specifically limit as an active catalyst seed | species, It is preferable to use copper. Although it does not specifically limit as copper as an active catalyst seed | species, Copper, nitrate, a sulfate, carbonate, acetate, a chloride, an oxide, and a hydroxide can be illustrated. Such copper or a substance containing copper is supported on the inner surface of the pore wall. Examples of the method of supporting copper or a substance containing copper on the inner surface of the pore wall of mesoporous silica include a liquid phase method, a solid phase method, and a gas phase method. In the liquid phase method, copper or a substance containing copper is dispersed or dissolved in a solvent such as water, ethanol, benzene, etc., and mesoporous silica is added to the liquid and stirred and mixed, so that copper as an active catalyst species is mesoporous. It is introduced into the inner surface of the pore wall of silica. In the solid phase method, a raw material compound of solid copper fine wire and mesoporous silica are mixed in a solid phase, heated in a closed container, and then excess raw material compound is removed by washing, etc. Copper is introduced into the pores of the mesoporous silica. In the gas phase method, a material that generates vapor such as metal alkoxide or a material that easily sublimes is used as a raw material, and by contacting the vapor with mesoporous silica, copper as an active catalyst species is placed in the pores of mesoporous silica. be introduced. Since copper can be uniformly introduced into the inner surface of mesoporous silica, the method of introducing copper is preferably a gas phase method or a liquid phase method.

Next, the present invention will be described in more detail with reference to examples, but the technical scope of the present invention is not limited by the following examples.
Example 1 Outer surface selective silylation of mesoporous silica Trialkylsilyl groups were used as organic groups used to modify the outer surface of mesoporous silica. As shown in FIG. 2 (a), a silane coupling agent that is usually widely used may have a possibility of self-polymerization of the reagent as shown in FIG. 2 (a). In this example, the reagent fixed as a monomolecular layer is used. Was used (FIG. 2B).
MCM-41 (a precursor of mesoporous silica) in the process of production without removing the surfactant is described in the literature (Z. Liu, Y. Sakamoto, T. Ohsuta, K. Hiraga, O. Terasaki, CH Ko, HJ Shin, R. Ryoo, Angew. Chem., Int. Ed., 39, 3107 (2000)). 1.0 g of this MCM-41 was heated at 353 K in 6.7 mL of dehydrated toluene in the presence of 0.32 mL (1.7 mmol, 3 equivalents of surface Si-OH group) of trimethylsilyl trifluoromethanesulfonate (Me ₃ SiOSO ₂ CF ₃ ). After 16 hours, after washing with toluene and methanol, it was heated twice at 373 K for 16 hours in ethanol-concentrated hydrochloric acid (93: 7, v / v) in order to remove the surfactant in the pores. After washing with ethanol, vacuum drying was performed at 393 K to obtain TMS-MCM in which only the outer surface was selectively silylated.

As a comparative sample, MCM-41 being produced was fired to obtain MCM-41 from which the surfactant in the pores was removed. This MCM-41 was also subjected to silylation treatment using trimethylsilyl trifluoromethanesulfonate in the same manner as above to obtain TMS-MCM-TMS in which both the inner and outer surfaces of the pore wall were silylated.
In order to investigate the types of silylating agents, 1,1-bis (trimethylsiloxy) -1-propene (1,1) was used in addition to trimethylsilyl trifluoromethanesulfonate using a reagent equivalent to 30 equivalents of surface Si-OH groups. 1-bis (trimethyl-silyloxy) -1-propene), 1,1,1,3,3,3-hexamethyldisilazane (1,1,1,3,3,3-hexamethyldisilazane), triethoxymethylsilane The product was compared using (triethoxymethylsilane) and trimethylchlorosilane (Me ₃ SiCl).
The mesopore structure was analyzed by powder X-ray diffraction (XRD) and nitrogen adsorption. Infrared spectroscopy and elemental analysis were used for the analysis of the silyl group introduced into mesoporous silica.

Example 2 Oxidative Polymerization Catalytic Reaction of 2,6-Dimethylphenol Using Copper-Supported Mesoporous Silica A catalyst supporting copper as an active catalyst species on a mesoporous silica surface was prepared using copper acetate as a precursor. Using this catalyst, an oxidative polymerization reaction of 2,6-dimethylphenol was carried out.
TMS-MCM and MCM-41 were each added 0.24 g to an acetonitrile solution (40 mL) of Cu (OAc) ₂ .H ₂ O (39 mg) and stirred gently. UV measurement of the solution confirmed that adsorption had reached equilibrium within 2 hours. Filtration and drying under reduced pressure were performed to obtain Cu / TMS-MCM (Cu 1.1 wt%) and Cu / MCM (Cu 0.78 wt%), respectively. The supported amount was determined by measuring the amount of adsorption of the precursor solution by UV measurement.
Catalytic reaction was conducted in a screw-tube test tube (diameter 10 mm, length 100 mm) using 2,6-dimethylphenol 0.3 mmol as a substrate (S / C = 50) and 0.5 mL of toluene in the presence of 0.1 mL of pyridine. The solvent was 298 K and an oxygen atmosphere.
For the reaction analysis, gas chromatography, NMR, and GPC were used.

<Results and discussion>
1. Outer surface selective silylation of mesoporous silica TMS-MCM was obtained by silylation of MCM-41 during production with trimethylsilyl trifluoromethanesulfonate and subsequent removal of the surfactant. As a comparative sample, ordinary MCM-41 was silylated with trimethylsilyl trifluoromethanesulfonate to obtain TMS-MCM-TMS.
From the powder XRD measurement, no change in the two-dimensional hexagonal arrangement of mesopores due to silylation was confirmed in any sample.
Next, nitrogen adsorption measurement was performed, and each value related to the mesopore structure was calculated from the analysis as shown in Table 1.

As a result, with respect to TMS-MCM-TMS, various values indicating remarkably silylation into the pores were obtained, and the progress of silylation into the pores was confirmed. In contrast, for TMS-MCM, a value almost equal to that of MCM-41 was obtained, indicating that silylation did not proceed on the inner surface of the mesopores.
The presence of the trimethylsilyl group introduced onto the mesoporous silica surface by silylation was confirmed by infrared spectroscopy (CH stretching: 2965, 2905 cm ^-1 ) and solid ¹ H NMR measurement (0.0 ppm).

The trimethylsilyl group density of TMS-MCM-TMS determined by elemental analysis was 2.4 ± 0.1 mmol g- ¹ . Based on the density of silanol groups in the mesoporous silica used and the density of the introduced trimethylsilyl groups, the ratio of silanol groups silylated was 42 ± 1% for TMS-MCM-TMS and 5 ± 1% for TMS-MCM. Calculated. For the latter, as described above, it was confirmed that silylation did not proceed on the inner surface, so the conversion rate of silanol groups on the outer surface was 43 ± 1%, and both the inner and outer surfaces were silylated TMS. The silylation efficiency was the same as -MCM-TMS. Considering the three-dimensional size of the trimethylsilyl group, it was considered that the silylation rate this time reached a nearly saturated value.

Next, silylation reagents were examined. 1,1-bis (trimethylsiloxy) -1-propene, 1,1,1,3,3,3-hexamethyldisilazane, triethoxymethyl instead of trimethylsilyl trifluoromethanesulfonate used in the study so far Silane and trimethylchlorosilane were used for selective silylation of the outer surface of MCM-41 during production, subsequent removal of the surfactant, and nitrogen adsorption measurement.
The BJH pore size distribution of each sample is shown in FIG. When 1,1-bis (trimethylsiloxy) -1-propene, 1,1,1,3,3,3-hexamethyldisilazane, or triethoxymethylsilane is used, the pore size is MCM-41. Since the pore size was significantly reduced, it became clear that silylation to the inner surface was progressing. In contrast, when trimethylchlorosilane was used, as in the case of using trimethylsilyl trifluoromethanesulfonate, no obvious change in pore diameter was observed, and silylation selective to the outer surface was achieved.
As described above, in the organic modification of mesoporous silica during production without removing the surfactant, it was confirmed that the modification into the pores partially progressed depending on the reagents and conditions used.

2. Oxidative polymerization catalytic reaction of 2,6-dimethylphenol using copper-supported mesoporous silica As an application to the catalytic reaction, as shown in (formula 1), copper acetate is supported on mesoporous silica as a precursor, Oxidative polymerization of 2,6-dimethylphenol (Y. Shibasaki, M. Nakamura, R. Ishimaru, JN Kondo, K. Domen, M. Ueda, Macromolecules, 37, 9657 (2004); Y. Shibasaki, M. Nakamura, R. Ishimaru, JN Kondo, M. Ueda, Chem. Lett. 34, 662 (2005)).

  This polymer is widely used as a thermoplastic resin. Cu / TMS-MCM and Cu / MCM were obtained by supporting copper species in acetonitrile solution on TMS-MCM, which was silylated selectively on the outer surface of the pore wall, and MCM-41 that had not been silylated. . The catalytic reaction was carried out in toluene in the presence of pyridine at room temperature in an oxygen atmosphere. The molecular weight distribution of the resulting polymer is shown in FIG. As shown in the figure, Cu / TMS-MCM gave a molecular weight distribution with apex of about 9,000 (see graph (a) in FIG. 4). On the other hand, Cu / MCM gave a polymer with a larger molecular weight distribution with the peak at about 16,000, and another molecular weight distribution in the range below the molecular weight of 6,000 (see graph (b) in Fig. 4). . As a comparison, when mesoporous silica was not used and copper acetate was used as a catalyst, a polymer with a broader molecular weight distribution centered at about 32,000 was given, and formation of a dimer was remarkably confirmed (in FIG. 4, (See graph (c)). Cu / MCM with active species supported on both the inner and outer surfaces gives a product with a large molecular weight, whereas Cu / TMS-MCM, which has active species only on the inner surface due to selective silylation on the outer surface, has a low molecular weight. And a product with a limited molecular weight distribution range.

  As described above, according to this embodiment, since the catalytic reaction is selectively performed in the internal space of the pores provided in the mesoporous silica, when the polymer is produced by performing the polymerization reaction in particular, the conventional catalyst is used. Compared to polymers, it was possible to produce polymers with a lower molecular weight and a narrower molecular weight distribution range.

Claims (6)

In the mesoporous silica having pores and pore walls forming the pores, the outer surface of the pore walls is selectively modified with an organic substance to regulate catalytic reaction, while the pore walls A catalyst characterized in that a catalytically active species is selectively fixed on the inner surface of the catalyst. The catalyst according to claim 1, wherein the average diameter of the pores is 1 nm to 20 nm. The catalyst according to claim 1 or 2, wherein the catalytically active species is copper. The catalyst according to any one of claims 1 to 3, wherein the catalyst is used for an oxidative polymerization reaction of a phenol compound. A method for producing a polymer, characterized in that a phenol compound is oxidatively polymerized using the catalyst according to any one of claims 1 to 4. A reaction mixture obtained by mixing a surfactant and a skeleton component is subjected to a polycondensation reaction, and a mesoporous silica precursor filled with the surfactant in pores defined by pore walls formed by the skeleton component is obtained. After the preparation, the outer surface of the mesoporous silica precursor is selectively modified with an organic reagent for modifying the hydroxyl group on the outer surface of the pore wall, and the surfactant in the pore is removed to remove the surfactant. The catalytically active species is selectively fixed to the inner surface of the pore wall after obtaining mesoporous silica whose surface is modified with an organic group. A method for producing a catalyst.

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