METHOD FOR PREPARATION OF HIERARCHICAL TS-1 MOLECULAR SIEVE

Abstract

The present application discloses a method for preparing a hierarchical porous TS-1 molecular sieve, which uses 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 mesoporous template in the synthesis process. The obtained TS-1 molecular sieve has mesoporous structure with narrow pore size distribution, which plays an important role in promoting the application of TS-1 molecular sieve in the field of catalysis.

Claims

1. A method for preparing hierarchical porous TS-1 molecular sieve, wherein a silicon-titanium ester polymer is used 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 shown in Formula I:
[Tia(RO.sub.x).sub.4/xSi.sub.(1−a)].sub.n   Formula I wherein, 0<a≤0.5, RO.sub.x is a group formed by losing H on OH of organic polyhydric alcohol R(OH).sub.x, and R is a group formed by losing x hydrogen atoms on hydrocarbon compound, x≥2, n=2˜30.

4. The method according to claim 3, wherein x=2, 3 or 4 in Formula I.

5. The method according to claim 3, wherein silicon-titanium ester polymer is at least one of silicon-titanium acid ethylene glycol polyester, silicon-titanium acid butylene glycol polyester, silicon-titanium acid polyethylene glycol polyester, silicon-titanium acid glycerol polyester, silicon-titanium acid terephthalyl alcohol polyester.

6. The method according to claim 2, wherein a molar ratio of silicon-titanium ester polymer, the template and water satisfies: template: silicon-titanium ester polymer=0.01˜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 based on the number of moles of SiO.sub.2, and the titanium content in the silicon-titanium ester polymer is based on the number of moles of TiO.sub.2; and the number of moles of water is based on the number of moles of H.sub.2O itself.

7. The method according to claim 6, wherein a molar ratio of the silicon-titanium ester polymer, the template and water satisfies: template: silicon-titanium ester polymer=0.05˜8; water: silicon-titanium ester polymer=10˜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 therein; a silicon content in the silicon-titanium ester polymer is based on the number of moles of SiO.sub.2. and a titanium content in the silicon-titanium ester polymer is based on the number of moles of TiO.sub.2; and the number of moles of water is based on the number of moles of H.sub.2O itself.

8. The method according to claim 2, wherein the template refers to at least one of organic base templates.

9. The method according to claim 8, wherein the organic base template includes A which is at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylpropylammonium hydroxide, tetrapropylammonium halide, tetraethylammonium halide, tetrabutylammonium halide, and triethylpropylammonium halide.

10. The method according to claim 9, wherein the organic base template further includes B which is at least one of aliphatic amine and alcohol amine compounds.

11. The method according to claim 10, B includes at least one of ethylamine, diethylamine, triethylamine, n-butylamine, butanediamine, hexamethylenediamine, octanediamine, monoethanolamine, diethanolamine, and triethanolamine.

12. The method according to claim 2, wherein conditions of crystallization are: 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.

13. The method according to claim 12, wherein conditions of crystallization are: the crystallization is conducted in sealed condition, a crystallization temperature ranges from 110 to 180° C., and a crystallization time under autogenous pressure ranges from 1 to 28 days.

14. The method according to claim 12, wherein conditions of crystallization are: the crystallization is conducted in sealed condition, a crystallization temperature ranges from 120 to 190° C., and a crystallization time under autogenous pressure ranges from 1 to 15 days.

15. The method according to claim 2, wherein the mixture undergoes crystallization after aging, and conditions of aging are that aging temperature is not higher than 120° C. for an aging time in a range from 0 to 100 hours.

16. The method according to claim 1 following steps: a) mixing the silicon-titanium ester polymer 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; b) crystalizing the gel mixture obtained in step a) 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 does not exceed 30 days under autogenous pressure.

17. The method according to claim 1, wherein the TS-1 molecular sieve comprises mesopores, and the pore diameter thereof ranges from 2 to 50 nm.

18. The method according to claim 1, wherein a particle size of the hierarchical porous TS-1 molecular sieve ranges from 100 to 500 nm.

19. 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 a TS-1 molecular sieve prepared by the method according to claim 1.

20. 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 a TS-1 molecular sieve prepared by the method according to claim 2.

Description

BRIEF DESCRIPTION OF FIGURES

[0096] FIG. 1 shows XRD pattern of the product prepared according to Example 1 of the present invention.

[0097] FIG. 2 shows SEM image of the product prepared according to Example 1 of the present invention.

[0098] FIG. 3 shows ultraviolet-visible (UV-VIS) spectrum of the product prepared according to Example 1 of the present invention.

[0099] 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

[0100] The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

[0101] Unless otherwise specified, the raw materials in the examples of the present application are all commercially available.

[0102] In 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.

[0103] In the present application, the SEM image of the product is obtained by Hitachi™3000 SEM.

[0104] In 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.

[0105] In 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.

[0106] In the present invention, the silicon-titanium ester polymer is used as both the silicon source and the titanium source, an organic base template and deionized water are added therein to synthesize the hierarchical porous TS-1 molecular sieve under hydrothermal conditions.

[0107] According to an embodiment of the present application, the method for preparing the hierarchical porous TS-1 molecular sieve is as follows:

[0108] a) mixing the silicon-titanium ester polymer, the organic base template and water in a certain proportion to obtain a gel mixture, wherein, preferably, the gel mixture has the following molar ratio: organic base template/(SiO.sub.2+TiO.sub.2)=0.01˜10; H.sub.2O/(SiO.sub.2+TiO.sub.2)=5 ˜500; 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;

[0109] b) subjecting the gel mixture obtained in step a) to an aging process, which can be omitted or can be carried out, wherein the aging can be carried out under stirring or static conditions, an aging temperature ranges from 0 to 120° C., and an aging time ranges from 0 to 100 hours;

[0110] c) transferring the gel mixture after step b) into a reactor 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., and a crystallization time ranges from 1 to 30 days;

[0111] d) 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;

[0112] wherein, the organic base template 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,n-butylamine, butanediamine, hexamethylene diamine, octanediamine, monoethanolamine, diethanolamine, triethanolamine and the like.

[0113] Preferably, the organic base template/(SiO.sub.2+TiO.sub.2)=0.05˜8 in the gel mixture in step a).

[0114] Preferably, H.sub.2O/(SiO.sub.2+TiO.sub.2)=10˜300 in the gel mixture in step a).

[0115] Preferably, the aging process in step b) can be omitted or can be carried out, wherein an aging temperature ranges from 20 to 80° C., and an aging time ranges from 0 to 80 hours.

[0116] Preferably, in step c), the crystallization temperature ranges from 120 to 190° C., and the crystallization time ranges from 1 to 15 days.

[0117] Preferably, the crystallization process in step c) is performed statically or dynamically.

[0118] Preferably, the hierarchical porous TS-1 molecular sieve is obtained in the step d).

EXAMPLE 1

[0119] 4.88 g tetrapropylammonium hydroxide (25 wt %) aqueous solution and 5 g water are added to 8 g silicon-titanium polyethylene glycol-200 polyester, which are mixed uniformly, and stirred at room temperature for 2 hours.

[0120] Then, the obtained mixture is transferred to a stainless steel autoclave, wherein the molar ratio of all components herein is [Ti.sub.0.05(RO.sub.x).sub.4/Si.sub.0.05].sub.n: 0.5TPAOH: 50H.sub.2O, R is hexyl, x=2, n=20. The autoclave is sealed and placed in an oven that has been raised to a constant temperature of 170° C., and crystallization step 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. The obtained hierarchical porous TS-1 molecular sieve 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 100 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 size distribution curves of the sample 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.

[0121] RO.sub.x is a group formed by losing x hydrogen atoms on the hydroxyl group on polyethylene glycol-200.

[0122] The method for preparing the silicon-titanium polyethylene glycol-200 polyester is as follows: 16.8 g PEG-200, 8.3 g tetraethyl orthosilicate and 0.5 g tetraethyl titanate are added into a three-necked flask which is connected to a distillation device, and then temperature is heat up to 175° C. under stirring and nitrogen protection, and the reaction time is 4 hours. During this process, a large amount of ethanol is distilled out, and the conversion rate of the transesterification is 90%. Then a vacuum device is connected to the distillation device, and the transesterification continues under vacuum distillation conditions, wherein the vacuum degree of the reaction system is controlled to be 1 kPa and the temperature is raised to 200° C. After reacting for 1 hour, the transesterification is stopped. After the temperature is naturally cooled to be room temperature, the resulting sample is taken, and the conversion rate of the transesterification is 95%.

[0123] The conversion rate of the transesterification in the Examples of the present application is calculated as follows.

[0124] 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 esters in the reaction raw materials is in, and then the conversion rate of the transesterification is n/xm; wherein x depends on the number of alkoxy groups connected to the central atom in the esters.

[0125] The prepared sample is subject to thermogravimetric test which is conducted by TA Q-600 thermogravimetric analyzer from TA Instruments. During the thermogravimetric test, the nitrogen flow rate is 100 ml/min, and the temperature is increased to 700° C. at a temperature rise rate of 10° C/min. According to the reaction conversion rate x, the degree of polymerization n of the product can be determined: n=1/(1−x). The chemical formula of the obtained sample is [Ti.sub.0.05(RO.sub.x).sub.4/xSi.sub.0.95].sub.n, wherein R is the group formed by the loss of two hydrogen atoms on the hydroxyl groups of polyethylene glycol 200, x=2, n=20.

EXAMPLES 2 To 13

[0126] The specific raw materials, amounts thereof and reaction conditions different from Example 1 are shown in Table 1 below, and the other procedures are the same as those in Example 1.

TABLE-US-00001 TABLE 1 Raw materials, amounts thereof and reaction conditions of Examples 2 to 13 Organic base Crystallization XRD External Example Silicon-titanium ester polymer compound water temperature Crystallization crystal specific surface Numbering (mol) (mol) (mol) (° C.) time (day) form area (m.sup.2 g.sup.−1) 2 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 50 mol 170 4 TS-1 185 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.5 mol groups of ethylene glycol, x = 2, n = 12 1 mol 3 [Ti.sub.0.01(RO.sub.x).sub.4/xSi.sub.0.90].sub.n Tetrapropylammonium 50 mol 170 4 TS-1 145 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.5 mol groups of 1,3-propanediol, x = 2, n = 11 5 mol 4 [Ti.sub.0.03(RO.sub.x).sub.4/xSi.sub.0.70].sub.n Tetrapropylammonium 50 mol 170 7 TS-1 162 R is a group formed by losing three hydroxide hydrogen atoms on the hydroxyl   1 mol groups of glycerol, x = 3, n = 10 2 mol 5 [Ti.sub.0.05(RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 10 mol 170 4 TS-1 130 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.05 mol  groups of 1,4-butanediol, x = 2, n = 12 0.02 mol   6 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 300 mol  170 1 TS-1 235 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl  10 mol groups of 1,6-hexanediol, x = 2, n = 15 2 mol 7 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 50 mol 100 20 TS-1 165 R is the group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.5 mol groups of terephthalyl alcohol, x = 2, n = 10 0.3 mol   8 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 50 mol 200 1 TS-1 210 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.5 mol groups of 1,4-cyclohexanediol, x = 2, n = 11 0.l mol   9 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 50 mol 170 7 TS-1 180 R is the group formed by losing two hydroxide hydrogen atoms on the hydroxyl 0.1 mol + 5 mol.sup.  groups of 1,4-cyclohexanedimethanol, n-butylamine x = 2, n = 16 l mol 10 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetrapropylammonium 50 mol 170 7 TS-1 175 R is a group formed by losing two bromide hydrogen atoms on the hydroxyl 0.5 mol + 10 mol  groups of polyethylene glycol 200, n-butylamine x = 2, n = 12 2 mol 11 [Ti.sub.0.15 (RO.sub.x).sub.4/xSi.sub.0.85].sub.n Tetrabutylammonium 150 mol  170 0.5 TS-1 150 R is a group formed by losing two hydroxide hydrogen atoms on the hydroxyl .sup. 1 mol + 0.1 mol groups of polyethylene glycol 400, tetrapropylammonium x = 2, n = 15 bromide 1 mol 12 [Ti.sub.0.05 (RO.sub.x).sub.4/xSi.sub.0.95].sub.n Tetraethylammonium 50 mol 170 3 TS-1 166 R is a group formed by polyethylene hydroxide glycol 800 losing two hydrogen atoms 0.5 mol + 0.5 mol on the hydroxyl group, tetrapropylammonium x = 2, n = 12 bromide 0.3 mol   13 [Ti.sub.0.05(RO.sub.x).sub.4/xSi.sub.0.95].sub.n Hexanediamine 50 mol 175 10 TS-1 140 R is a group formed by losing four  10 mol + 0.1 mol hydrogen atoms on the hydroxyl tetrapropylammonium groups of pentaerythritol, bromide x = 4, n = 16 3 mol In Table 1, R is the group formed by losing x hydrogen atoms of hydrocarbon compounds, and is exemplified by ethyl, propyl, butyl, polyethylene glycol group, terephthalate group, x ranges from 2 to 6. The crystallization in Examples 1 to 13 is static crystallization.

[0127] The method for preparing the silicon-titanium ester polymer in Examples 2 to 13 is the same as the method for preparing the silicon-titanium polyethylene glycol-200 ester polymer in Example 1. The difference is that 16.8 g polyethylene glycol 200 in Example 1 is replaced with 5 g ethylene glycol, 6.1 g 1,3-propanediol, 5 g glycerol, 7.2 g 1,4-butanediol, 9.5 g 1,6-hexanediol, 11.1 g terephthalyl alcohol, 9.3 g 1,4-cyclohexanediol, 11.5 g 1,4-cyclohexane dimethanol, 33.8 g polyethylene glycol 400, 65.6 g polyethylene glycol 800, 5.5 g pentaerythritol, respectively, to obtain the corresponding silicon-titanium ester polymer in Examples 2 to 13.

EXAMPLE 14

[0128] Except that the crystallization temperature is 100° C. and the crystallization time is 30 days, the other procedures are the same as those in Example 1.

[0129] The crystallization is dynamic, which is performed by using a rotating oven. The crystallization temperature and crystallization time are the same as those in Example 1, and the rotation speed of the rotating oven is 35 rpm.

EXAMPLE 15

[0130] Aging step is performed before crystallization, and the aging step is performed statically at 120° C. for 2 hours. The other procedures are the same as those in Example 1.

EXAMPLE 16

[0131] Aging step is performed before crystallization, and the aging step is performed at 20° C. for 80 hours. The other procedures are the same as those in Example 1.

EXAMPLE 17

Phase Structure Analysis

[0132] The samples prepared in Example 1 to Example 16 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 prepared in Example 1. As can be seen from FIG. 1, the sample in Example 1 is proved to be TS-1 molecular sieve.

[0133] 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 18

Morphology Test

[0134] The samples prepared in Example 1 to Example 16 are subjected to SEM morphology analysis respectively, results of which are typically shown in FIG. 2. FIG. 2 shows the SEM image of the sample prepared in Example 1. As can be seen from FIG. 2, the particle size of the sample in Example 1 is about 200 nm.

[0135] The test results of other samples are similar to the test result of the sample in Example 1, and the particle size of the samples ranges from 100 to 300 nm.

EXAMPLE 19

Spectrum Analysis

[0136] The samples prepared in Example 1 to Example 16 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 prepared in Example 1. As can be seen from FIG. 3, the sample of Example 1 almost has no non-framework titanium.

[0137] The test results of other samples are similar to those of the sample in Example 1, and there is almost no non-framework titanium in the sample.

EXAMPLE 20

Pore Size Distribution Analysis

[0138] The samples prepared in Example 1 to Example 16 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 prepared in Example 1. As can be seen from FIG. 4, the sample has mesopores of about 2 nm, and thus the pore size distribution of the sample is narrow.

[0139] The test results of other samples are similar to the test result of sample 1 in Example 1, and the samples all have mesopores of which the pore sizes range from 2 to 50 nm.

[0140] 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.