METHOD FOR PREPARING TS-1 MOLECULAR SIEVE WITH HIERARCHICAL PORES

Abstract

The present application discloses a method for preparing a hierarchical porous TS-1 molecular sieve comprising using a silicon-titanium ester polymer as both titanium source and silicon source. In the method, silicon and titanium are uniformly connected to a same polymer, and the hydrolysis rates thereof are equivalent during hydrolysis, which can prevent TiO.sub.2 precipitation and reduce the generation of non-framework titanium. Further, the silicon-titanium ester polymer is not only used as both silicon source and titanium source, but also can be used as a mesoporous template in the synthesis process. The obtained TS-1 molecular sieve has mesoporous structure with narrow pore size distribution.

Claims

1. A method for preparing hierarchical porous TS-1 molecular sieve comprising using a silicon-titanium ester polymer as both titanium source and silicon source.

2. The method according to claim 1 comprising performing crystallization of a mixture containing the silicon-titanium ester polymer, a template and water to obtain the hierarchical porous TS-1 molecular sieve, wherein the crystallization is hydrothermal crystallization.

3. The method according to claim 1, wherein the silicon-titanium ester polymer is obtained by transesterification of raw materials containing silicate, titanate and polyhydric alcohol; wherein a molar ratio of the silicate, titanate and polyhydric alcohol satisfies: titanate:silicate=0.001˜0.2; (titanate+silicate):polyhydric alcohol=(0.5˜5)x: 4; wherein, x is the number of moles of hydroxyl groups contained in each mole of the polyhydric alcohol; and the number of moles of each component is calculated by the number of moles of the substance itself; wherein the transesterification is carried out in an inactive atmosphere, a reaction temperature ranges from 80 to 180° C. and a reaction time ranges from 2 to 10 hours.

4. (canceled)

5. The method according to claim 3, wherein, the molar ratio of the silicate, titanate and polyhydric alcohol satisfies: titanate:silicate=0.005˜0.1; (titanate+silicate):polyhydric alcohol=(0.8˜1.2)x: 4; wherein, x is the number of moles of hydroxyl groups contained in each mole of the polyhydric alcohol; and the number of moles of each component is calculated by the number of moles of the substance itself.

6. (canceled)

7. The method according to claim 63, wherein the transesterification is carried out in an inactive atmosphere, a reaction temperature ranges from 100 to 160° C. and a reaction time ranges from 4 to 8 hours.

8. The method according to claim 3, wherein the transesterification further comprises performing vacuum distillation, wherein conditions of the vacuum distillation comprise that a vacuum degree ranges from 0.01 to 5 kPa, a vacuum distillation temperature ranges from 170 to 230° C., and a vacuum distillation time ranges from 0.5 to 5 hours; preferably, the vacuum degree ranges from 0.05 to 3 kPa.

9. (canceled)

10. (canceled)

11. The method according to claim 3, wherein the silicate is at least one of compounds having a chemical formula shown in Formula I: ##STR00003## wherein, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently selected from C.sub.1 to C.sub.10 alkyl group.

12. The method according to claim 11, wherein the silicate comprises at least one of tetramethoxysilane, tetratetraethyl orthosilicate, tetrapropyl silicate and tetrabutyl silicate.

13. The method according to claim 3, wherein the titanate is at least one of compounds having a chemical formula shown in Formula II, ##STR00004## wherein, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently selected from C.sub.1 to C.sub.10 alkyl group.

14. The method according to claim 13, wherein the titanate includes at least one of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate, and tetraisooctyl titanate; preferably, the polyhydric alcohol comprises at least one of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butylene glycol, 1,6-hexanediol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800, 1,4-cyclohexanediol, 1,4-cyclohexane dimethanol, terephthalyl alcohol, glycerin, trimethylolpropane, pentaerythritol, xylitol and sorbitol.

15. (canceled)

16. The method according to claim 3, wherein a method for preparing the silicon-titanium ester polymer comprises: mixing silicate, titanate and polyhydric alcohol, and then performing transesterification under stirring conditions and in an inactive protection atmosphere, wherein a reaction temperature ranges from 80 to 180° C., and a reaction time ranges from 2 to 10 hours; and performing vacuum distillation to prepare the silicon-titanium ester polymer, during which a vacuum degree ranges from 0.01 to 5 kPa, a reaction temperature ranges from 170 to 230° C., and a reaction time ranges from 0.5 to 5 hours.

17. (canceled)

18. The method according to claim 2, wherein a molar ratio of the silicon-titanium ester polymer, template and water satisfies: template:silicon-titanium ester polymer=0.05˜10, water:silicon-titanium ester polymer=5˜500; wherein, the number of moles of the template is based on the number of moles of N atom in the template; the number of moles of the silicon-titanium ester polymer is based on the sum of silicon content and titanium content in the silicon-titanium ester polymer; the silicon content in the silicon-titanium ester polymer is calculated by the number of moles of SiO.sub.2 and the titanium content in the silicon-titanium ester polymer is calculated by the number of moles of TiO.sub.2; and the number of moles of the water is based on the number of moles of H.sub.2O itself.

19. The method according to claim 18, wherein the molar ratio of the silicon-titanium ester polymer, template and water satisfies: template:silicon-titanium ester polymer=0.1˜5; water:silicon-titanium ester polymer=30˜300; wherein, the number of moles of the template is based on the number of moles of N atom in the template; the number of moles of the silicon-titanium ester polymer is based on the sum of silicon content and titanium content in the silicon-titanium ester polymer; the silicon content in the silicon-titanium ester polymer is calculated by the number of moles of SiO.sub.2, and the titanium content in the silicon-titanium ester polymer is calculated by the number of moles of TiO.sub.2; and the number of moles of the water is based on the number of moles of H.sub.2O itself.

20. The method according to claim 2, wherein the template refers to at least one of organic base templates, preferably, the organic base template comprises A which is at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylpropylammonium hydroxide, tetrapropylammonium halide, tetraethylammonium halide, tetrabutylammonium halide and triethylpropylammonium halide.

21. (canceled)

22. The method according to claim 20, wherein the organic base template further includes B which is at least one of aliphatic amine and alcohol amine compounds, preferably, B comprises at least one of ethylamine, diethylamine, triethylamine, n-butylamine, butanediamine, hexamethylenediamine, octanediamine, monoethanolamine, diethanolamine and triethanolamine.

23. (canceled)

24. The method according to claim 2, wherein conditions of the crystallization are as follows: the crystallization is conducted in sealed condition, a crystallization temperature ranges from 100 to 200° C., and a crystallization time under autogenous pressure does not exceed 30 days; preferably, the mixture undergoes crystallization after aging, and conditions of aging are that an aging temperature is not higher than 120° C. for an aging time in a range from 0 to 100 hours.

25. The method according to claim 24, wherein conditions of the crystallization are as follows: the crystallization is conducted in sealed condition, a crystallization temperature ranges from 120 to 180° C., and a crystallization time under autogenous pressure ranges from 1 to 15 days.

26. (canceled)

27. The method according to claim 1 comprising: a) mixing silicate, titanate and polyhydric alcohol, and then performing the transesterification under stirring conditions and in an nitrogen atmosphere for protection, wherein the reaction temperature ranges from 80 to 180° C., and the reaction time ranges from 2 to 10 hours; b) after the reaction in step a), performing vacuum distillation to prepare the silicon-titanium ester polymer, during which a vacuum degree ranges from 0.01 to 5 kPa, a reaction temperature ranges from 170 to 230° C., and a reaction time ranges from 0.5 to 5 hours; c) mixing the silicon-titanium ester polymer obtained in step b) with an organic base template and water, and keeping the obtained mixture at a temperature not higher than 120° C. for aging for a time in a range from 0 to 100 hours to obtain a gel mixture; d) crystalizing the gel mixture obtained in step c) under sealed conditions to obtain the hierarchical porous TS-1 molecular sieve, wherein a crystallization temperature is raised to a range from 100 to 200° C., and a crystallization time ranges from 0 to 30 days under autogenous pressure.

28. The method according to claim 1, wherein the hierarchical porous TS-1 molecular sieve comprises mesopores, and a pore diameter thereof ranges from 2 to 10 nm; preferably, a particle size of the hierarchical porous TS-1 molecular sieve ranges from 100 to 500 nm.

29. (canceled)

30. A method for selective oxidation of organic substances in the presence of H.sub.2O.sub.2, the method comprising subjecting the organic substances and the H.sub.2O.sub.2 to Use the hierarchical porous TS-1 molecular sieve prepared by the method according to claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

[0092] FIG. 1 shows XRD pattern of the product prepared according to Example 1 of the present invention.

[0093] FIG. 2 shows SEM image of the product prepared according to Example 1 of the present invention.

[0094] FIG. 3 shows ultraviolet-visible (UV-VIS) spectrum of the product prepared according to Example 1 of the present invention.

[0095] FIG. 4 shows the results of physical adsorption and pore size distribution of the product prepared according to Example 1 of the present invention.

DETAILED DESCRIPTION

[0096] The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

[0097] Unless otherwise specified, the raw materials in the examples of the present application are all commercially available.

[0098] In the examples of the present application, the X-Ray Diffraction Analysis (XRD) of the product is performed by the X′ Pert PRO X-Ray Diffractometer from PANalytical Company, wherein the XRD is performed under conditions of the Cu target Kα radiation source (λ=0.15418 nm), electric voltage=40 KV, and electric current=40 mA.

[0099] In the present application, the SEM image of the product is obtained by Hitachi SU8020 SEM.

[0100] In the examples of the present application, the ultraviolet-visible diffuse reflectance spectrum of the product is measured on a Varian Cary500 Scan UV-Vis spectrophotometer equipped with an integrating sphere.

[0101] In the examples of the present application, the physical adsorption, external specific surface area and pore size distribution analysis of the product are performed by the ASAP2020 automatic physics instrument from Mike.

[0102] The conversion rate of the transesterification in the Examples of the present application is calculated as follows: according to the number of moles n of the by-product alcohols distilled out during the reaction, the number of groups participating in the transesterification is determined to be n, and the total number of moles of silicate and titanate in the reaction raw materials is in, and then the conversion rate of the transesterification is n/4 m.

[0103] According to an embodiment of the present application, the method for preparing the hierarchical porous TS-1 molecular sieve is as follows: [0104] a) mixing silicate, titanate and polyhydric alcohol uniformly in a three-necked flask, and performing the transesterification under stirring conditions during which a distillation device is connected to the three-necked flask and nitrogen is passed in the three-necked flask for protection, wherein the reaction temperature ranges from 80 to 180° C., the reaction time ranges from 2 to 10 hours, and the conversion rate of the transesterification ranges from 60% to 80%; [0105] b) after step a), connecting the distillation device to the water pump or oil pump for vacuum distillation to make the transesterification more complete to obtain the silicon-titanium ester polymer, wherein the vacuum degree is controlled to range from 0.01 to 5 kPa, the reaction temperature ranges from 170 to 230° C., the reaction time ranges from 0.5 to 5 hours, and the conversion rate of the transesterification is greater than 90%; [0106] c) mixing the silicon-titanium ester polymer obtained in step b) with an organic base template and water, and keeping the obtained mixture at a temperature not higher than 120° C. for aging for a time in a range from 0 to 100 hours to obtain a gel mixture; [0107] d) transferring the gel mixture obtained in step c) into a autoclave which is then sealed, and crystalizing the gel mixture under the condition that the crystallization temperature is raised to a range from 100 to 200° C., a crystallization time ranges from 0 to 30 days under autogenous pressure; [0108] e) after the crystallization is completed, separating the solid product, washing the same with deionized water to be neutral, and drying the same to obtain the hierarchical porous TS-1 molecular sieve; [0109] wherein, the silicate in step a) is one or more of tetramethoxysilane, tetratetraethyl orthosilicate, tetrapropyl silicate and tetrabutyl silicate; [0110] the titanate in step a) is at least one of tetraethyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate and tetraisooctyl titanate; [0111] the formula of the polyhydric alcohol in step a) is R—(OH).sub.x, wherein x>≥2; the polyhydric alcohol comprises at least one of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butylene glycol, 1,6-hexanediol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800, 1,4-cyclohexanediol, 1,4-cyclohexane dimethanol, terephthalyl alcohol, glycerin, trimethylolpropane, pentaerythritol, xylitol and sorbitol.

[0112] Preferably, in the step a), the molar ratio of the silicate, titanate and polyhydric alcohol satisfies: Ti(OR).sub.4/Si(OR).sub.4=0.005˜0.1,[Ti(OR).sub.4+Si(OR).sub.4]/R—(OH).sub.x=(0.8-1.2)x/4.

[0113] Preferably, the reaction in step a) is carried out under nitrogen atmosphere, a reaction temperature ranges from 80 to 180° C. and the reaction time ranges from 2 to 10 hours.

[0114] Preferably, the conversion rate of the transesterification in step a) ranges from 65% to 80%.

[0115] Preferably, the step b) is carried out under vacuum distillation conditions, and the vacuum degree thereof ranges from 0.05 to 3 kPa.

[0116] Preferably, in step b), the reaction temperature ranges from 170 to 230° C., and the reaction time ranges from 0.5 to 5 hours.

[0117] Preferably, the conversion rate of the transesterification in step b) is greater than 90%.

[0118] Preferably, in step c), the molar ratio of the silicon-titanium ester polymer, organic base template and water satisfies: organic base template/(SiO.sub.2+TiO.sub.2)=0.1˜5, H.sub.2O/(SiO.sub.2+TiO.sub.2)=30˜300; wherein, the silicon content in the silicon-titanium ester polymer is calculated by the number of moles of SiO.sub.2, the titanium content in the silicon-titanium ester polymer is calculated by the number of moles of TiO.sub.2 and the content of the organic base template is calculated by the number of moles of N atom; [0119] wherein, the organic base template used in step c) is at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylpropylammonium hydroxide, tetrapropylammonium halide, tetraethylammonium halide, tetrabutylammonium halide, triethylpropylammonium halide and the like; alternatively, the organic base template is a mixture of these quaternary ammonium salts or quaternary ammonium bases and aliphatic amine or alcohol amine compounds which is exemplified as ethylamine, diethylamine, triethylamine, n-butylamine, butanediamine, hexamethylenediamine, octanediamine, monoethanolamine, diethanolamine and triethanolamineand the like.

[0120] Preferably, the aging process in step c) can be omitted or can be carried out, wherein an aging temperature ranges from 20 to 100° C., and an aging time ranges from 1 to 50 hours.

[0121] Preferably, the aging process in step c) is performed statically or dynamically.

[0122] Preferably, in step d), the crystallization temperature ranges from 120 to 180° C., and the crystallization time ranges from 1 to 15 days.

[0123] Preferably, the crystallization process in step d) is performed statically or dynamically.

[0124] Preferably, the hierarchical porous TS-1 molecular sieve obtained in the step e) has a mesoporous structure with a narrower pore size distribution and less non-framework titanium.

Example 1

[0125] The specific process is as follows: 5 g tetraethyl orthosilicate, 0.29 g tetraethyl titanate and 10 g polyethylene glycol 200 are added into a three-necked flask and mixed uniformly to carry out the transesterification under stirring conditions and nitrogen protection. The three-necked flask is connected to a distillation device. The temperature is heated up to 175° C., the reaction time is 5 hours, and the conversion rate of the transesterification is 75%. Then a water pump is connected to distillation device to perform vacuum distillation and further make transesterification more complete, wherein the vacuum degree of the reaction system was controlled to be 3 kPa and the temperature was raised to 200° C. After reacting for 1 hour, the conversion rate of the transesterification is 92% and the silicon-titanium polyethylene glycol ester polymer is obtained. The obtained silicon-titanium polyethylene glycol ester polymer, 8 g tetrapropylammonium hydroxide (25 wt % aqueous solution) and 12 g water are mixed. The obtained mixture is subjected to aging process at room temperature for 2 hours under stirring conditions, and then is transferred to a stainless steel autoclave, wherein the molar ratio of all components therein is Ti.sub.0.05(PEG-200).sub.2Si.sub.0.95:0.4TPAOH:40H.sub.2O. The autoclave is sealed and placed in an oven that has been raised to a constant temperature of 170° C., and crystallization under autogenous pressure is performed for 2 days. After crystallization is completed, the solid product is separated by centrifugation, washed with deionized water to be neutral, and dried in air at 110° C. to obtain a hierarchical porous TS-1 molecular sieve which is labeled as C1. The obtained hierarchical porous TS-1 molecular sieve (sample C1) is subject to XRD analysis, the result of which is shown in FIG. 1. As can be seen from FIG. 1, the obtained sample is proved to be TS-1 molecular sieve. The SEM image of the obtained hierarchical porous TS-1 molecular sieve is shown in FIG. 2. As can be seen from FIG. 2, the particle size thereof is around 200 nm. The UV-VIS diffuse reflectance spectrum of the obtained hierarchical porous TS-1 molecular sieve is shown in FIG. 3. As can be seen from FIG. 3, almost no non-framework titanium exists in the obtained hierarchical porous TS-1 molecular sieve. The physical adsorption and pore distribution curves of the sample C1 are shown in FIG. 4. As can be seen from FIG. 4, the obtained hierarchical porous TS-1 molecular sieve has mesopores of about 2 nm.

Example 2

[0126] The specific process is as follows: 5 g tetraethyl orthosilicate, 0.05 g tetraethyl titanate and 3.13 g ethylene glycol are added into a three-necked flask and mixed uniformly to carry out the transesterification under stirring conditions and nitrogen protection. The three-necked flask is connected to a distillation device. The temperature is heated up to 100° C., the reaction time is 5 hours, and the conversion rate of the transesterification is 70%. Then a water pump is connected to distillation device to perform vacuum distillation and further make transesterification more complete, wherein the vacuum degree of the reaction system was controlled to be 3 kPa and the temperature was raised to 170° C. After reacting for 1 hour, the conversion rate of the transesterification is 90% and the silicon-titanium ethylene glycol ester polymer is obtained. The obtained silicon-titanium ethylene glycol ester polymer, 2 g tetrapropylammonium hydroxide (25 wt % aqueous solution) and 3 g water are mixed. The obtained mixture is subjected to aging process at room temperature for 2 hours under stirring conditions, and then is transferred to a stainless steel autoclave, wherein the molar ratio of all components therein is Ti.sub.0.01(OCH.sub.2CH.sub.2O).sub.2Si.sub.0.99:0.1TPAOH:10H.sub.2O. The autoclave is sealed and placed in an oven that has been raised to a constant temperature of 120° C., and crystallization under autogenous pressure is performed for 15 days. After crystallization is completed, the solid product is separated by centrifugation, washed with deionized water to be neutral, and dried in air at 110° C. to obtain a hierarchical porous TS-1 molecular sieve which is labeled as C2.

Example 3

[0127] The specific process is as follows: 5 g tetramethoxysilane, 2.8 g tetrabutyl titanate and 11.35 g terephthalyl alcohol are added into a three-necked flask and mixed uniformly to carry out the transesterification under stirring conditions and nitrogen protection. The three-necked flask is connected to a distillation device. The temperature is heated up to 160° C., the reaction time is 5 hours, and the conversion rate of the transesterification is 80%. Then a water pump is connected to distillation device to perform vacuum distillation and further make transesterification more complete, wherein the vacuum degree of the reaction system was controlled to be 3 kPa and the temperature was raised to 230° C. After reacting for 1 hour, the conversion rate of the transesterification is 95% and the silicon-titanium terephthalyl alcohol ester polymer is obtained. The obtained silicon-titanium terephthalyl alcohol ester polymer, 330 g tetrapropylammonium hydroxide (25 wt % aqueous solution) and 120 g water are mixed uniformly. The obtained mixture is subjected to aging process at room temperature for 2 hours under stirring conditions, and then is transferred to a stainless steel autoclave, wherein the molar ratio of all components therein is Ti.sub.0.2(OC.sub.6H.sub.4O).sub.2Si.sub.0.8:10TPAOH:500H.sub.2O. The autoclave is sealed and placed in an oven that has been raised to a constant temperature of 180° C., and crystallization under autogenous pressure is performed for 1 day. After crystallization is completed, the solid product is separated by centrifugation, washed with deionized water to be neutral, and dried in air at 110° C. to obtain a hierarchical porous TS-1 molecular sieve which is labeled as C3.

[0128] The crystallization in Examples 1 to 3 is static crystallization.

Example 4

[0129] The hierarchical porous TS-1 molecular sieve in the present example was prepared by the similar method to in Example 1. The specific preparation conditions different from Example 1 are shown in Tables 1 and 2.

TABLE-US-00001 TABLE 1 Parameters and conditions for preparing silicon-titanium ester polymer Vacuum Silicate, titanate, Vacuum Vacuum degree of polyhydric alcohol and Reaction Reaction distillation distillation vacuum Numbering the molar ratio thereof temperature time temperature time distillation 1# Tetrapropyl  80° C. 10 hours 180° C. 3 hours 0.01 kPa silicate:tetraisopropyl titanate:glycerol = 2.4:0.6:4 2# tetrabutyl  90° C. 8 hours 210° C. 2.5 hours 0.05 kPa silicate:tetrahexyl titanate:pentaerythritol = 0.75:0.25:1 3# tetrapropyl 120° C. 4 hours 170° C. 5 hours 5 kPa silicate:tetraisooctyl titanate:1,2-propanediol = 0.8:0.2:2 4# tetrabutyl 180° C. 2 hours 230° C. 0.5 hour 1.5 kPa silicate:tetrahexyl titanate:1,4-cyclohexanediol = 0.7:0.3:2

TABLE-US-00002 TABLE 2 Conditions for preparing hierarchical porous TS-1 molecular sieve Crystallization Aging temperature, silicon-titanium ester polymer, organic base temperature, crystallization Numbering template, water and the molar ratio thereof aging time time C4 1#: tetrabutylammonium hydroxide (10 wt % aqueous 20° C., 50 100° C., 30 days solution):water = 1:1.5:20 hours, static aging C5 2#: tetraethylammonium hydroxide (25 wt % aqueous // 150° C., 10 days solution):water = 1:0.6:40 C6 3#: tetrabutylammonium hydroxide (10 wt % aqueous 120° C., 1 200° C., 5 days solution) + diethanolamine:water = 1:2:50 hour, static aging C7 4#: tetraethylammonium hydroxide (25 wt % aqueous 100° C.,10 180° C., 8 days solution) + diethylamine:water = 1:1:10 hours, static aging

[0130] The crystallization in Example 4 is performed dynamically, which is performed by using a rotating oven. The crystallization temperature and crystallization time are shown in table 2, and the rotation speed of the rotating oven is 35 rpm.

Example 5 Phase Structure Analysis

[0131] The samples C1 to C7 prepared in Example 1 to Example 4 are subjected to XRD phase structure analysis respectively, results of which are typically shown in FIG. 1. FIG. 1 shows the XRD pattern of the sample C1 prepared in Example 1. As can be seen from FIG. 1, the sample in Example 1 is proved to be TS-1 molecular sieve.

[0132] The test results of other samples are only slightly different from the samples in Example 1 in terms of the intensity of the diffraction peaks, and they are all proved to be TS-1 molecular sieves.

Example 6 Morphology Test

[0133] The samples C1 to C7 prepared in Example 1 to Example 4 are subjected to SEM morphology analysis respectively, results of which are typically shown in FIG. 2. FIG. 2 shows the SEM spectrum of the sample C1 prepared in Example 1. As can be seen from FIG. 2, the particle size of the sample in Example 1 is about 200 nm.

[0134] The test results of other samples are similar to the test result of the sample C1 in Example 1, and the particle size of the samples ranges from 100 to 500 nm.

Example 7 Spectrum Analysis

[0135] The samples C1 to C7 prepared in Example 1 to Example 4 were subjected to UV-VIS diffuse reflectance spectrum analysis respectively, results of which are typically shown in FIG. 3. FIG. 3 shows UV-VIS diffuse reflectance spectrum of the sample C1 prepared in Example 1. As can be seen from FIG. 3, the sample of Example 1 almost has no non-framework titanium.

[0136] The test results of other samples are similar to those of the sample C1 in Example 1, and there is almost no non-framework titanium in the sample.

Example 8 Pore Size Distribution Analysis

[0137] The samples prepared in Example 1 to Example 4 are subjected to physical adsorption and pore size distribution analysis respectively, results of which are typically shown in FIG. 4. FIG. 4 shows the results of physical adsorption and pore distribution of the sample C1 prepared in Example 1. As can be seen from FIG. 4, the sample has mesopores of about 2 nm.

[0138] The test results of other samples are similar to the test result of sample C1 in Example 1, and the samples all have mesopores of which the pore sizes range from 2 to 10 nm.

[0139] The above examples are only illustrative, and do not limit the present application in any form. Any change or modification, made by the skilled in the art based on the technical content disclosed above, without departing from the spirit of the present application, is equivalent example and falls within the scope of the present application.