Titanosilicate and its manufacturing method, method for oxidizing phenols, and method for manufacturing dihydric phenols

Abstract

To provide titanosilicate with easily manufacturable zeolite as a basic skeleton, that exhibits catalytic performance.SOLUTION: Titanosilicate according to the present invention is obtained by replacing part of aluminum inside a skeleton of FAU-type zeolite by titanium, and a content ratio (Si / Ti) of silicon to titanium is 20 or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a titanosilicate and a method for producing the same, a method for oxidizing phenols, and a method for producing dihydric phenols. [Background technology]

[0002] Aluminosilicate MCM-68 is a relatively new zeolite first synthesized by Mobil (Patent Document 1). This zeolite has a structure in which large pores (12-membered ring pores) and medium pores (10-membered ring pores) intersect three-dimensionally. This type of zeolite generally has a large surface area and large internal space, making it useful as a catalyst in oil refining and petrochemical processes, and as a catalyst for relatively bulky organic molecules as substrates.

[0003] MCM-68 has a Si / Al ratio of 9 to 12, which means it has a relatively high Al content, i.e., a relatively high active site, and is therefore stable, making it suitable for use as an acid catalyst. Furthermore, MCM-68 has a high hydrocarbon adsorption capacity and exhibits high activity in reactions involving hydrocarbons, such as the alkylation of aromatic hydrocarbons and the transalkylation, isomerization, disproportionation, and dealkylation of alkylaromatic hydrocarbons. Therefore, MCM-68 is expected to be a base material for hydrocarbon conversion catalysts.

[0004] Zeolites with the FAU topology (FAU aluminosilicates) are known as starting materials for synthesizing 8-membered ring zeolites such as CHA, AEI, AFX, and ERI. FAU aluminosilicates are widely used industrially because they do not require structure-directing agents for synthesis and can be obtained at low cost.

[0005] FAU-type aluminosilicates are classified into X-type zeolites, which have a silicon-to-aluminum content ratio (Si / Al) of less than 2, and Y-type zeolites, which have a silicon-to-aluminum content ratio (Si / Al) of more than 2. X-type zeolites can be used, for example, as adsorbents with high ion exchange capacity and hydrophilicity. Y-type zeolites can be used, for example, as solid acid catalysts for fluid catalytic cracking in the petrochemical industry.

[0006] Since the safety of general zeolites increases as the Si / Al ratio increases, Y-type zeolites, which have a relatively low Al content, are used as solid acid catalysts that are stable under high-temperature conditions. Zeolites with even greater stability can be obtained by treating Y-type zeolites with steam and acid to remove the aluminum. The resulting zeolites are called USY (Ultra Stable Y)-type zeolites and are important industrial catalysts.

[0007] On the other hand, titanium silicalite-1 (TS-1) is a representative titanosilicate zeolite, and is known to exhibit high activity and selectivity as a catalyst for the oxidation reaction of organic compounds, etc. (Patent Document 2). One known method for synthesizing a zeolite with high catalytic activity like TS-1 is to introduce titanium into the zeolite by treating dealuminated mordenite with high-temperature TiCl4 vapor (Non-Patent Document 1). Also known is a method for producing a titanosilicate with catalytic performance equal to or better than that of TS-1 by replacing the aluminum that makes up MCM-68 with titanium (Patent Document 3). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2002-535227 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-175801 [Patent Document 3] Patent No. 4923248 [Non-patent literature]

[0009] [Non-Patent Document 1] J.Phys.Chem.1996,100,10316-10322 Summary of the Invention [Problem to be solved by the invention]

[0010] Conventional methods for producing titanosilicates are based on the idea of ​​treating aluminosilicate with acid, removing aluminum, and then modifying the vacant sites with titanium. However, when acid treatment is performed on the versatile FAU-type aluminosilicate, silicon fills the vacant sites left by the removal of aluminum atoms before titanium can reach them, making it difficult to modify with titanium. Therefore, several studies have been conducted to introduce zeolites with new structures that enable titanium modification after acid treatment, but the difficulty of producing these zeolites has been an issue.

[0011] The present invention has been made in view of the above circumstances, and a first object thereof is to provide a titanosilicate having catalytic properties and a basic skeleton of zeolite that can be easily produced, and a method for producing the same. A second object thereof is to provide a method for oxidizing phenols and a method for producing dihydric phenols using the titanosilicate as a catalyst. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention employs the following means.

[0013] (1) A titanosilicate according to one embodiment of the present invention is formed by substituting titanium for part of the aluminum in the framework of an FAU zeolite, and has a silicon to titanium content ratio (Si / Ti) of 20 or more.

[0014] (2) In the titanosilicate described in (1) above, the silicon to aluminum content ratio (Si / Al) is preferably 1.5 or more.

[0015] (3) In the titanosilicate according to either (1) or (2) above, it is preferable that the titanosilicate has a peak in the wavelength range of 200 nm to 230 nm in the UV-vis spectrum.

[0016] (4) In the titanosilicate according to any one of (1) to (3), the water vapor adsorption amount is preferably 50% or less compared to when the aluminum in the framework of the FAU-type zeolite is not replaced with titanium.

[0017] (5) In the titanosilicate according to any one of (1) to (4) above, hydrogen is preferably contained in the pores of the FAU-type zeolite.

[0018] (6) A method for producing a titanosilicate according to one embodiment of the present invention is the method for producing a titanosilicate according to any one of (1) to (5) above, and includes a titanium treatment step of heating the FAU zeolite, with aluminum contained in the framework, together with a gaseous titanium source and a reaction gas, and the FAU zeolite used has a silicon to aluminum content ratio (Si / Al) of 1.5 or more.

[0019] (7) The method for producing titanosilicate according to (6) above preferably further comprises a step of removing unreacted titanium by heating the FAU zeolite after the titanium treatment step together with a reaction gas.

[0020] (8) The method for producing titanosilicate according to either (6) or (7) above may further include a calcination step of calcining the mixture at a temperature of 300°C or higher and 800°C or lower after the titanium treatment step or the unreacted titanium removal step.

[0021] (9) A method for oxidizing a phenol according to one aspect of the present invention comprises oxidizing a phenol using the titanosilicate according to any one of (1) to (5) above as a catalyst.

[0022] (10) A method for producing a dihydric phenol according to one aspect of the present invention includes oxidizing a phenol using the method for oxidizing a phenol described in (9) above, and using phenol as the phenol.

[0023] (11) In the method for producing a dihydric phenol according to (10), ethanol may be added as a solvent for the phenol and the titanosilicate.

[0024] (12) In the method for producing a dihydric phenol according to (10) above, dihydric propanol may be added as a solvent for the phenol and the titanosilicate. [Effects of the Invention]

[0025] The present invention provides a titanosilicate having catalytic properties and a basic skeleton of a readily producible zeolite, as well as a method for producing the same. The present invention also provides a method for oxidizing phenols and a method for producing dihydric phenols using the titanosilicate as a catalyst. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an apparatus for performing titanium treatment on an aluminosilicate. [Figure 2] FIG. 2 is a diagram illustrating heating conditions associated with titanium treatment. [Figure 3] FIG. 1 is a diagram illustrating heating conditions for a firing treatment after titanium treatment. [Figure 4] 1 is a graph showing the results of X-ray diffraction analysis of the titanosilicates of Examples 1 to 4. [Figure 5] 1 is a graph showing the results of X-ray diffraction analysis of the titanosilicates of Examples 5 to 7. [Figure 6] 1 is a graph showing the results of X-ray diffraction analysis of the titanosilicate of Example 8. [Figure 7] 1 is a graph showing the results of DR / UV-vis measurement for titanosilicates of Examples 1 to 4 and Comparative Example 1. [Figure 8] 1 is a graph showing the results of DR / UV-vis measurement for titanosilicates of Examples 5 to 7 and Comparative Example 1. [Figure 9] 1 is a graph showing the results of DR / UV-vis measurement for titanosilicates of Examples 1, 5, 7, and 8 and Comparative Example 1. [Figure 10] 1 is a graph showing the evaluation results of the amount of water vapor adsorption for the titanosilicate of Example 8 on a real scale. [Figure 11] 1 is a graph showing the evaluation results of the amount of water vapor adsorption for the titanosilicate of Example 8 on a semi-logarithmic scale. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, titanosilicates and their production methods, phenol oxidation methods, and dihydric phenol production methods according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions enlarged for ease of understanding, and the dimensional ratios of the components may not necessarily be the same as in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications may be made within the scope of the present invention.

[0028] A titanosilicate according to one embodiment of the present invention has a basic skeleton of a large-pore zeolite having an FAU topology (hereinafter referred to as an FAU aluminosilicate or FAU zeolite), with some of the aluminum in the skeleton replaced with titanium. FAU aluminosilicates are classified into X-type zeolite, Y-type zeolite, USY-type zeolite, and the like, depending on the silicon-to-aluminum ratio (Si / Al) in the skeleton. Zeolites with a ratio (Si / Al) of 1.0 to 1.5 are called X-type zeolites, those with a ratio (Si / Al) of 1.5 to 3.0 are called Y-type zeolites, and those with a ratio of more than 5.0 are called USY-type zeolites.

[0029] In the titanosilicate of this embodiment, the content ratio (Si / Ti) of silicon (Si) to titanium (Ti) in the skeleton is 20 or more, preferably 50 or more, and more preferably 100 or more. Although it is sufficient for even a small amount of titanium to be contained in the skeleton, it is preferable for the content ratio (Si / Ti) to be 1000 or less. The content ratio (Si / Ti) can be measured, for example, using an ICP-AES method.

[0030] Furthermore, in the titanosilicate of this embodiment, the silicon (Si) to aluminum (Al) content ratio (Si / Al) is 1.5 or more, preferably 100 or more, and more preferably 500 or more. Furthermore, aluminum may not be contained in the skeleton at all, but the content ratio (Si / Al) may be 1000 or less. The content ratio (Si / Al) can be measured, for example, using an ICP-AES method.

[0031] The titanium atoms contained in the titanosilicate of this embodiment have a tetracoordinated crystal structure and are properly incorporated into the framework. The crystalline structure of the titanium atoms can be confirmed by the peak position of the UV-vis spectrum. If the peak of the UV-vis spectrum is in the wavelength range of 200 nm to 230 nm, it is considered that the titanium atoms have a tetracoordinated crystal structure.

[0032] The water vapor adsorption capacity of the titanosilicate of this embodiment is 10% to 50% and preferably 10% to 20% based on the state in which aluminum in the framework is not replaced with titanium (a state without titanium treatment). In other words, the hydrophobicity of the titanosilicate of this embodiment, which has an FAU zeolite framework, is increased by the titanium treatment. Therefore, even in an uncalcined state, the titanosilicate of this embodiment has a high hydrophobicity equivalent to that of a calcined titanosilicate having a framework of a zeolite other than the FAU zeolite.

[0033] The titanosilicate of this embodiment contains hydrogen atoms in the pores constituting the FAU zeolite. The content ratio of hydrogen atoms (H / (Na+H)) based on the total amount of hydrogen atoms and sodium atoms located at the ion exchange sites is preferably 95% or more and 100% or less.

[0034] As described above, the titanosilicate of this embodiment has a highly versatile FAU-type zeolite skeleton and is highly hydrophobic. Therefore, a high proportion of titanium atoms are introduced into the skeleton, and the titanosilicate has excellent catalytic performance, as will be described later in the examples.

[0035] [Method for producing titanosilicate] The method for producing titanosilicate of this embodiment mainly includes a first step of preparing an FAU-type aluminosilicate, and second and third steps of introducing titanium into the FAU-type aluminosilicate. A firing step (fourth step) may be included after the third step. The treatment in each production step will be described below.

[0036] (first step) First, a crystallized FAU-type aluminosilicate (FAU-type zeolite) is prepared. As the FAU-type aluminosilicate, commercially available products can be used. As examples, products commercially available from Tosoh Corporation and Zeolyst International are listed in Tables 1 and 2, respectively. The contents of Table 1 can be found on the Internet.<URL:https: / / www.tosoh.co.jp / zeolite / hsz / list01.html> The contents of Table 2 are disclosed on the Internet.<URL:https: / / www.zeolyst.com / our-products / standard-zeolite-powders / zeolite-y.html> The structure of any of the FAU-type aluminosilicates, including those listed in Tables 1 and 2, can be uniquely identified from the results of analysis by X-ray diffraction (XRD).

[0037] [Table 1]

[0038] [Table 2]

[0039] (Second process) The prepared FAU-type aluminosilicate powder is subjected to a titanium treatment, i.e., a treatment for introducing (modifying) titanium into each site constituting the FAU-type framework. Specifically, the FAU-type aluminosilicate powder is heated together with a gaseous titanium source (e.g., titanium chloride, titanium alkoxide, etc.) and a reactive gas (e.g., an inert gas such as argon, nitrogen, or helium) in a state where the framework contains about 5% to 20% aluminum. This treatment allows titanium to be introduced into at least some of the aluminum sites constituting the framework of the FAU-type aluminosilicate, while also removing aluminum from the aluminum sites where titanium has been introduced. As a result, at least some of the aluminum constituting the FAU-type aluminosilicate is replaced with titanium. FIG. 1 is a diagram showing an example of the configuration of a titanium treatment apparatus 10.

[0040] The titanium processing apparatus 10 mainly comprises a glass tube 11, a heater 12 arranged around the glass tube 11, a temperature controller 13 connected to the heater 12, a container 14 containing a titanium source, and an inert gas supply source 15. The glass tube 11, the titanium source container 14, and the inert gas supply source 15 are connected to one another by tubes via a four-way valve 16, and are configured so that the inert gas can be switched between a flow path that goes directly to the glass tube 11 and a flow path that goes via the titanium source container 14 to the glass tube 11 at any time.

[0041] The procedure for titanium treatment will be described with reference to Fig. 1. First, powdered FAU-type aluminosilicate crystals S are surrounded by a fibrous material (not shown) such as quartz wool and fixed inside a glass tube 11 via this fibrous material.

[0042] First, the flow path is switched so that the inert gas flows directly into the glass tube 11, and the FAU-type aluminosilicate crystals S are heated in a state where an inert gas such as argon, nitrogen, or helium is circulated through the glass tube 11. The heating temperature is preferably 300°C or higher and 800°C or lower, and more preferably about 500°C. The heating time is preferably 1 hour or higher and 12 hours or lower, and more preferably about 4 hours.

[0043] Subsequently, the flow path of the inert gas is switched to one that passes through the titanium source container 14 and heads toward the glass tube 11, and the FAU-type aluminosilicate crystals S are heated while the inert gas and the titanium source, titanium chloride or titanium alkoxide in gas phase, are circulated through the glass tube 11.

[0044] FIG. 2 is a diagram illustrating the heating conditions for titanium treatment. First, the FAU-type aluminosilicate crystals S are heated at a substantially constant rate over a period of about 4 hours to a predetermined heating temperature. The heating temperature is preferably 300°C or higher and 800°C or lower, and more preferably about 600°C. Once the heating temperature is reached, the temperature is maintained for the set heating time. The heating time is preferably 0.5 hours or higher and 6 hours or lower, and more preferably about 1 hour. This heating introduces titanium into at least some of the sites constituting the framework of the FAU-type aluminosilicate. After the heating time has elapsed, the heating is stopped and the crystals are cooled.

[0045] Examples of titanium chlorides used here include TiCl4, TiCl3, etc. Examples of titanium alkoxides used here include Ti(OMe)4, Ti(OEt)4, Ti(OPr)4, Ti(OPr-i)4, Ti(OBu)4, etc.

[0046] (Third step) Next, the flow path is switched so that the inert gas flows directly into the glass tube 11, and the inert gas is again circulated through the glass tube 11 without changing the heating temperature or heating time. This removes any unreacted titanium source remaining in the crystal structure of the FAU-type aluminosilicate after the introduction of titanium. After the removal of the unreacted titanium source, the FAU-type aluminosilicate is allowed to cool to room temperature, washed with distilled water, and dried in an oven at approximately 80°C.

[0047] The above-described process allows for the synthesis of titanosilicate, which has a basic skeleton of FAU-type aluminosilicate and in which some of the aluminum has been replaced by titanium. The silicon-to-titanium (Si / Ti) content ratio in the skeleton of the synthesized titanosilicate is generally 50 or more. This content ratio can be adjusted by the heating conditions.

[0048] (Fourth step) From the viewpoint of increasing the ortho selectivity, the synthesized titanosilicate may be further calcined. FIG. 3 is a diagram illustrating the heating conditions for the calcination treatment after the titanium treatment. First, the titanosilicate is heated to the calcination temperature at a substantially constant rate in the range of about 0.8°C / min to 1.2°C / min, preferably at a rate of about 1°C / min. The calcination temperature is preferably in the range of 300°C to 800°C, and more preferably about 650°C. Once the calcination temperature is reached, the temperature is maintained for the set calcination time. The calcination time is preferably in the range of 1 hour to 12 hours, and more preferably about 4 hours. After the calcination time has elapsed, the calcination is stopped and the mixture is allowed to cool.

[0049] As described above, according to the method for producing a titanosilicate of this embodiment, a titanosilicate having an FAU-type basic skeleton can be obtained. Since FAU-type aluminosilicate is easy to produce and is one of the most widely used zeolites, this technology, which makes it possible to introduce titanium into this zeolite, is expected to make a significant contribution to industrial development.

[0050] According to the method for producing a titanosilicate of this embodiment, aluminum atoms are present at each site constituting the framework until just before the titanium atoms reach it, thereby avoiding the problem of silicon atoms interfering with the introduction of titanium atoms. Furthermore, titanosilicates having an FAU-type aluminosilicate as their basic framework have sufficiently high hydrophobicity even in an uncalcined state, making it easy to attract titanium atoms to each site constituting the framework, and thus maintaining a stable crystal structure. Therefore, according to the method for producing a titanosilicate of this embodiment, acid treatment is not required when introducing titanium into frameworks other than the FAU-type, and the calcination treatment can be omitted, thereby significantly simplifying the process compared to conventional production methods.

[0051] [Method for oxidizing phenol and method for producing dihydric phenol] Phenols can be oxidized by an oxidation reaction using the titanosilicate as a catalyst. The phenols to be oxidized are not particularly limited, but examples thereof include phenol, cresol, aminophenol, salicylic acid, etc.

[0052] Dihydric phenols can be produced by oxidizing phenol. As will be described later in the Examples, the dihydric phenols produced mainly include hydroquinone HQ (the para-isomer of dihydric phenols), catechol CL (the ortho-isomer of dihydric phenols), and parabenzoquinone p-BQ, which is obtained by further oxidizing hydroquinone HQ. Solvents for the phenol and titanosilicate used in the reaction include, but are not necessarily, ethanol, dihydric propanol, acetonitrile, sulfolane, and the like.

[0053] The phenol oxidation reaction of this embodiment tends to produce catechol CL in high yield, which can be used in pharmaceuticals, etc. This yield can be adjusted by changing the ratio of silicon to titanium (Si / Ti) contained in the titanosilicate catalyst. [Example]

[0054] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention.

[0055] Examples 1 to 4 Four samples of approximately 1.0 g each of HSZ-360HUA manufactured by Tosoh Corporation were prepared as FAU-type aluminosilicate crystals. Using the titanium treatment device 10 shown in FIG. 1, the four samples (Examples 1 to 4) were each subjected to titanium treatment (second step) separately according to the following procedure. The ratio of silicon to aluminum (Si / Al) contained in HSZ-360HUA was 8.07.

[0056] First, a crystal S of HSZ-360HUA was surrounded by quartz wool and fixed inside the quartz tube 11 via the quartz wool.

[0057] Next, the flow path was switched so that the argon gas was directed directly to the glass tube 11, and the crystal S was heated while argon gas was flowing through the quartz tube 11. The temperature was increased from room temperature to about 700°C at an almost constant rate over about 4 hours.

[0058] Next, the flow path of argon gas was switched to pass through the titanium source container 14 and head toward the glass tube 11, and the crystal S was heated while argon gas and titanium tetrachloride gas, which serves as the titanium source, were flowing through the quartz tube 11. The heating temperature was about 700°C, and the heating time was about 1 hour. The flow rate of the argon gas was 30 mL / min.

[0059] Next, the flow path was switched so that the inert gas was directed directly to the quartz tube 11, and the inert gas was again circulated through the quartz tube 11 for about 1 hour without changing the heating temperature or heating time, thereby removing the unreacted titanium source remaining in the crystal S (third step).

[0060] Finally, the crystals S were allowed to cool to room temperature over about 10 minutes, washed with distilled water, and dried in an oven at about 80°C.

[0061] By the above-mentioned process treatment, titanosilicates of Examples 1 to 3, which have the basic skeleton of an FAU-type aluminosilicate and in which part of Al is replaced by Ti, could be synthesized.

[0062] The synthesized titanosilicates of Examples 1 and 3 were further calcined (fourth step). Specifically, the temperature was raised at a constant rate from room temperature to about 650°C over about 10 hours and 20 minutes in an air atmosphere, maintained at about 650°C for about 4 hours, and then allowed to cool.

[0063] (Examples 5 and 6) Two samples of approximately 1.0 g each of HSZ-360HUA manufactured by Tosoh Corporation were prepared as FAU-type aluminosilicate crystals. The two samples (Examples 5 and 6) were treated in the same manner as in Examples 1 and 3, except that the temperature at which they were heated together with the titanium source was approximately 600°C.

[0064] Example 7 As the FAU-type aluminosilicate crystals, one sample of approximately 1.0 g of HSZ-360HUA manufactured by Tosoh Corporation was prepared. This sample (Example 7) was subjected to the same treatment as in Examples 1 and 3, except that the temperature at which it was heated together with the titanium source was set to approximately 650°C.

[0065] Example 8 As the FAU-type aluminosilicate crystal, one sample of approximately 1.0 g of HSZ-370HUA manufactured by Tosoh Corporation was prepared. The ratio of silicon to aluminum (Si / Al) contained in HSZ-370HUA was 15. This sample (Example 8) was subjected to the same treatment as in Examples 5 and 6.

[0066] The silicon to aluminum content ratio (Si / Al) and the silicon to titanium content ratio (Si / Ti) were measured for the titanosilicates obtained in Examples 1 to 8. The measurement results are shown in Table 3.

[0067] (Comparative Example 1) Titanium silicalite-1 (TS-1), designated and distributed by the Catalysis Society of Japan as the Asia Reference Catalyst (ARC), was prepared.

[0068] [Table 3]

[0069] [Evaluation of X-ray diffraction patterns] X-ray diffraction (XRD) analysis was performed on the samples of Examples 1 to 8. Diffraction patterns showing the analysis results are shown in the graphs of Figures 4 to 6. The horizontal axis of the graph represents the diffraction angle, and the vertical axis represents the diffraction intensity.

[0070] The graph in Figure 4 shows the diffraction patterns obtained for a crystalline sample of HSZ-360HUA under the following conditions: First stage: Initial state before titanium treatment (state after the first step in the above embodiment) Second row: Example 1, titanium treatment was performed but no firing was performed Third row: Example 1, titanium treatment and firing Fourth row: Example 2, titanium treatment was performed but no firing was performed Fifth row: Example 3, titanium treatment was performed but no firing was performed Sixth row: Example 3, after titanium treatment and firing Seventh row: Example 4, titanium treatment was performed but no firing was performed

[0071] The graph in Figure 5 shows a series of diffraction patterns obtained for a crystalline sample of HSZ-360HUA under the following conditions: First stage: Initial state before titanium treatment (state after the first step in the above embodiment) Second row: Example 5, titanium treatment was performed but no firing was performed Third row: Example 5, titanium treatment and firing Fourth row: Example 6, titanium treatment was performed but no firing was performed Fifth row: Example 6, after titanium treatment and firing Sixth row: Example 7, titanium treatment was performed but no firing was performed Seventh row: Example 7, after titanium treatment and firing

[0072] The graph in Figure 6 shows a series of diffraction patterns obtained for a crystalline sample of HSZ-370HUA under the following conditions: First stage: Initial state before titanium treatment (state after the first step in the above embodiment) Second row: Example 8, titanium treatment was performed but no firing was performed Third row: Example 8, titanium treatment and firing

[0073] Comparing the graphs in Figures 4 to 6, it can be seen that similar XRD patterns were obtained for all samples. These results show that high crystallinity was maintained before and after each process, regardless of whether the Si / Al ratio was changed between 6.8 and 15, or whether the titanium treatment temperature was changed between 600°C and 700°C. It also shows that reproducibility was obtained between different samples treated under the same conditions.

[0074] [Evaluation of Ti coordination state] DR / UV-vis measurements were carried out on the samples of Examples 1 to 8. The DR / UV-Vis spectra showing the measurement results are shown in the graphs of Figures 7 to 9. The horizontal axis of the graph represents wavelength (nm), and the vertical axis represents the Kubelka-Munk function.

[0075] The graph in Figure 7 shows the DR / UV-Vis spectra obtained under the following conditions for a crystalline sample of HSZ-360HUA and a crystalline sample of titanium silicalite-1. First row: Comparative example 1, titanium treatment was performed but no firing was performed Second row: Example 1, titanium treatment was performed but no firing was performed Third row: Example 1, titanium treatment and firing Fourth row: Example 2, titanium treatment was performed but no firing was performed Fifth row: Example 3, titanium treatment was performed but no firing was performed Sixth row: Example 3, after titanium treatment and firing Seventh row: Example 4, titanium treatment was performed but no firing was performed

[0076] The graph in Figure 8 shows the DR / UV-Vis spectra obtained under the following conditions for a crystalline sample of HSZ-360HUA and a crystalline sample of titanium silicalite-1. First row: Comparative example 1, titanium treatment was performed but no firing was performed Second row: Example 5, titanium treatment was performed but no firing was performed Third row: Example 5, titanium treatment and firing Fourth row: Example 6, titanium treatment was performed but no firing was performed Fifth row: Example 6, after titanium treatment and firing Sixth row: Example 7, titanium treatment was performed but no firing was performed Seventh row: Example 7, after titanium treatment and firing

[0077] The graph in Figure 9 shows the DR / UV-Vis spectra obtained under the following conditions for a crystalline sample of HSZ-370HUA and a crystalline sample of titanium silicalite-1. First row: Comparative example 1, titanium treatment was performed but no firing was performed Second row: Example 8, titanium treatment was performed but no firing was performed Third row: Example 8, titanium treatment and firing Fourth row: Example 5, titanium treatment was performed but no firing was performed Fifth row: Example 5, after titanium treatment and firing Sixth row: Example 7, titanium treatment was performed but no firing was performed Seventh row: Example 1, titanium treatment was performed but no firing was performed

[0078] The wavelength region of 200 to 230 nm is a region showing absorption corresponding to tetracoordinated Ti within the framework, and the wavelength region of 250 to 290 nm is a region showing absorption corresponding to pentacoordinated or hexacoordinated Ti outside the framework.

[0079] 7 to 9, the DR / UV-Vis spectra for the samples of Examples 1 to 8 all have peaks in the wavelength region of 200 to 230 nm. These results demonstrate that titanium was successfully incorporated into the FAU-type framework of the synthesized titanosilicate when the Si / Al ratio was varied between 6.8 and 15 and when the titanium treatment temperature was varied between 600 and 700°C. Furthermore, reproducibility was achieved between different samples treated under the same conditions.

[0080] [Evaluation of water vapor adsorption amount] The water vapor adsorption amount at 25°C was evaluated for samples in the following three states of Example 1 (state before titanium was introduced, state immediately after titanium was introduced, and state after titanium was introduced and calcined). The water vapor adsorption isotherms used for the evaluation are shown in the graphs of Figures 10 and 11 on a linear scale and a semi-logarithmic scale, respectively. The horizontal axis of the graph represents relative pressure, and the vertical axis represents the water vapor adsorption amount. Here, the state before titanium was introduced is plotted with a square, the state immediately after titanium was introduced is plotted with a triangle, and the state after titanium was introduced and calcined is plotted with a circle.

[0081] A comparison of the state before and immediately after the introduction of titanium shows that the introduction of titanium significantly reduces the amount of water vapor adsorption, resulting in hydrophobicity. More specifically, the amount of water vapor adsorption by the aluminum in the framework of the FAU-type aluminosilicate is approximately 30% to 50% of that when not replaced with titanium. On the other hand, a comparison of the state immediately after the introduction of titanium with the state after calcination after the introduction of titanium shows that the amount of water vapor adsorption is almost the same before and after calcination, and almost no hydrophobicity due to calcination is observed.

[0082] [Evaluation of catalytic performance for phenol oxidation reaction] Using the samples of Examples 5 to 7 as catalysts, an experiment was carried out on the phenol oxidation reaction shown in the following chemical reaction formula.

[0083] [ka]

[0084] The specific experimental procedure is as follows. First, 20 mg of catalyst, 2.00 g (21.3 mmol) of phenol, and 0.48 g (4.25 mmol) of hydrogen peroxide (30 wt%) were mixed in a glass pressure vessel and stirred at 100°C for 60 minutes. After the reaction was completed, the vessel was cooled on ice and diluted with 2.0 g (16.64 mmol) of sulfolane. 0.225 g (2.08 mmol) of anisole was added as an internal standard substance and mixed thoroughly, after which the reaction mixture was separated from the catalyst by centrifugation (3500 rpm, 10 minutes).

[0085] Next, approximately 150 mg of the supernatant was mixed with an excess of acetic anhydride (approximately 0.4 g) and potassium carbonate (approximately 0.6 g). The reaction mixture was maintained at approximately 20-50°C for 30 minutes with occasional shaking to thoroughly acetylate the phenolic compounds present. The mixture was then diluted with chloroform and analyzed using a gas chromatograph (Shimadzu GC-2014, FID detector, DB-1 column, 0.25 mm x 30 m x 1.00 μm). To quantify the unreacted hydrogen peroxide, 0.5 g of the centrifuged supernatant and 0.8 g of potassium iodide were added to 50 mL of 2.0 mol / L aqueous hydrochloric acid, and the mixture was titrated with an aqueous sodium thiosulfate solution at an exact concentration of approximately 0.1 mol / L.

[0086] As a result of the above analysis, hydroquinone (para isomer of dihydric phenol) HQ, catechol (ortho isomer of dihydric phenol) CL, and parabenzoquinone p-BQ, which is further oxidized from HQ, were detected.

[0087] Table 4 shows the calcination status of each sample, Ti content, catalyst turnover number (TON), yield, para-isotope selectivity (p-sel. (%)), H2O2 conversion rate (H2O2 (%) conv.), and effective utilization rate of H2O2 (H2O2 (%) eff.) in this experiment. (eff. is an abbreviation for efficiency.)

[0088] [Table 4]

[0089] The sum of the yields of HQ, p-BQ, and CL is shown as the total yield. The selectivity for the para isomer (p-sel.) is shown as the sum of HQ and p-BQ divided by the total. TON (catalytic turnover number) is the total amount of product (number of moles) divided by the number of moles of Ti active sites. In other words, TON is an indicator of how many times the catalytic cycle went through from the start of the reaction to the end of the reaction (60 minutes in this case).

[0090] H2O2 (%)eff. (effective utilization rate of H2O2) is the effective utilization rate of hydrogen peroxide, and is an index showing the efficiency with which oxygen in hydrogen peroxide is involved in phenol oxidation.

[0091] The results in Table 4 show that all samples exhibited phenol oxidation activity and para selectivity, indicating that titanosilicates with catalytic functionality were obtained. In particular, it can be seen that the catalytic functionality (yield, TON, etc.) in the uncalcined state of all samples exceeded that in the calcined state. This result is unique and cannot be seen when frameworks other than FAU are used.

[0092] Furthermore, the results in Table 4 show that the para selectivity decreases and the ortho selectivity increases by calcination. This result suggests that the para selectivity and ortho selectivity can be adjusted by changing the calcination temperature. [Explanation of symbols]

[0093] 10 Titanium processing equipment 11 Quartz tube 12 Heater 13 Temperature Controller 14 Titanium source container 15 Inert gas source 16 Four-way valve S crystal

Claims

1. A part of aluminum in the framework of FAU zeolite is replaced with titanium, The silicon to titanium content ratio (Si / Ti) is 20 or more, A titanosilicate characterized in that the amount of water vapor adsorption is 50% or less compared to when the aluminum in the framework of the FAU-type zeolite is not replaced with titanium.

2. 2. The titanosilicate according to claim 1, wherein the silicon to aluminum content ratio (Si / Al) is 1.5 or more.

3. 3. The titanosilicate according to claim 1, which has a peak in the wavelength range of 200 nm to 230 nm in the UV-vis spectrum.

4. 4. The titanosilicate according to claim 1, wherein hydrogen is contained in the pores of the FAU-type zeolite.

5. A method for producing the titanosilicate according to any one of claims 1 to 4, a titanium treatment step of heating the FAU zeolite, with aluminum contained in the framework, together with a gaseous titanium source and a reaction gas; A method for producing titanosilicate, characterized in that the FAU-type zeolite has a silicon to aluminum content ratio (Si / Al) of 1.5 or more.

6. 6. The method for producing titanosilicate according to claim 5, further comprising a step of heating the FAU zeolite after the titanium treatment step together with a reaction gas to remove unreacted titanium.

7. A method for producing titanosilicate as described in claim 6, further comprising a calcination step of performing calcination at 300°C or higher and 800°C or lower after the unreacted titanium removal step.

8. A method for oxidizing phenols, comprising oxidizing phenols using the titanosilicate according to any one of claims 1 to 4 as a catalyst.

9. The phenols are oxidized using the method for oxidizing phenols according to claim 8, A method for producing a dihydric phenol, wherein phenol is used as the phenol.

10. 10. The method for producing a dihydric phenol according to claim 9, wherein ethanol is added as a solvent for the phenol and the titanosilicate.

11. 10. The method for producing a dihydric phenol according to claim 9, wherein dihydric propanol is added as a solvent for the phenol and the titanosilicate.

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