Process for the production of a zeolitic material employing elemental precursors

Abstract

The present invention relates to a process for the production of a zeolitic material having a framework structure comprising YO2, wherein said process comprises: (1) preparing a mixture comprising one or more tetravalent elements Y in elemental form, one or more organic hydroxide salts, and one or more protic solvents; (2) reacting the mixture obtained in step (1) for converting at least part of the one or more tetravalent elements Y into an oxidic form thereof containing one or more YO single bonds and/or one or more YO double bonds; and (3) crystallizing a zeolitic material from the mixture obtained in step (2).

Claims

1. A process for producing a zeolitic material having a framework structure comprising YO.sub.2, the process comprising: (1) preparing a first mixture comprising two or more tetravalent elements Y in elemental form, organic hydroxide salts, and one or more protic solvents; (2) reacting the first mixture for converting at least part of the tetravalent elements Y into an oxidic form thereof comprising YO single bonds and/or YO double bonds, thereby obtaining a second mixture; and (3) crystallizing a zeolitic material from the second mixture, thereby obtaining a crystallization product, wherein the crystalizing is conducted under solvothermal conditions; wherein the tetravalent elements Y comprise a mixture of Si and Ti, wherein both Si and Ti are in elemental forms, and wherein after (2) and prior to (3) the second mixture is freed from solid matter.

2. The process of claim 1, wherein the first mixture further comprises one or more trivalent elements X in elemental form for producing a zeolitic material having a framework structure comprising YO.sub.2 and X.sub.2O.sub.3, and wherein in (2) at least part of the one or more trivalent elements X is converted into an oxidic form thereof.

3. The process of claim 2, wherein the one or more trivalent elements X in elemental form are selected from the group consisting of Al, B, In, Ga, and a mixture of two or more thereof.

4. The process of claim 2, wherein after (2) and prior to (3) one or more sources for X.sub.2O.sub.3 are further added to the second mixture for producing a zeolitic material having a framework structure comprising YO.sub.2 and X.sub.2O.sub.3.

5. The process of claim 4, wherein X in the one or more sources for X.sub.2O.sub.3 are selected from the group consisting of Al, B, In, Ga, and a mixture of two or more thereof.

6. The process of claim 2, wherein in the second mixture crystallized in (3) a molar ratio of a total amount of the tetravalent elements Y to a total amount of the one or more trivalent elements X ranges from 1 to 1,000.

7. The process of claim 1, wherein after (2) and prior to (3) one or more sources for YO.sub.2 are further added to the second mixture.

8. The process of claim 7, wherein Y in the one or more sources for YO.sub.2 is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and a mixture of two or more thereof.

9. The process of claim 1, wherein the second mixture crystallized in (3) comprises 1 wt. % or less of one or more elements M based on 100 wt. % of the tetravalent elements Y calculated as the elements, wherein M stands for at least one of sodium and potassium.

10. The process of claim 9, wherein M stands for sodium and potassium.

11. The process of claim 1, wherein the one or more protic solvents comprise one or more solvents selected from the group consisting of an alkanol, water, and a mixture of two or more thereof.

12. The process of claim 1, wherein a pH of the second mixture in (3) ranges from 13 to 16.

13. The process of claim 1, wherein the one or more organic hydroxide salts comprises one or more cationic organotemplates.

14. The process of claim 1, wherein in the first mixture a molar ratio of a total amount of the one or more organic hydroxide salts to a total amount of the tetravalent elements Y in elemental form ranges from 0.1 to 15.

15. The process of claim 1, wherein the reacting (2) involves heating of the first mixture.

16. The process of claim 1, wherein the crystallizing (3) involves heating of the second mixture.

17. The process of claim 1, said process further comprising at least one of (4) isolating the zeolitic material; (5) washing the zeolitic material; (6) drying, calcining, or both drying and calcining the zeolitic material; and (7) subjecting the zeolitic material to an ion-exchange procedure.

18. The process of claim 17, wherein after (3) and prior to (4) a pH of the crystallization product is adjusted to a pH in a range of from 5 to 9.

19. The process of claim 17, wherein the-process comprises the calcining (6), which is conducted at a temperature in a range of 300 to 850 C.

Description

DESCRIPTION OF THE FIGURES

(1) FIGS. 1, 5B, and 6B respectively show a scanning electron micrograph (SEM) of the respective zeolite product which was obtained according to Examples 1, 5B, and 6B, respectively, using a magnification of 5,000:1. At the lower right hand corner of the SEM micrographs, a unit length corresponding to 5 m in the image is indicated as a checkered bar with 5 subunits of 1 m, respectively.

(2) FIGS. 2-4 respectively show the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the crystalline materials obtained according to Examples 2-4. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are plotted along the ordinate. For comparison, the line patter of ZSM-5 has been included in the spectra.

(3) FIG. 5A shows the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the crystalline material obtained according to Example 5. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are plotted along the ordinate. For comparison, the line patter of ZSM-5 has been included in the spectra.

(4) FIGS. 6A and 7 respectively show the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the crystalline materials obtained according to Examples 6 and 7. In the respective figures, the angle 2 theta in is shown along the abscissa and the intensities are plotted along the ordinate. For comparison, the line patter of TS-1 has been included in the respective spectra.

(5) FIG. 8 shows the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the crystalline material obtained according to Example 8. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are plotted along the ordinate. For comparison, the line patter of ZSM-5 has been included in the diffractogram.

EXAMPLES

Example 1

Synthesis of Silicalite using Silicon Powder

(6) In a round bottom flask equipped with a reflux condenser and sealed with the aid of a gas bubbler, 2.1 g of silicon powder (325 mesh) were suspended in 170 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. during 10 h, during which silicon dissolved until a light grey hazy residue remained in the solution. The solution was filtered prior to its transfer to an autoclave. The reaction mixture thus obtained displayed a pH of 15.27.

(7) The autoclave was heated to 170 C. and held at that temperature for 24 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was filtered and the solid was washed several times with water. The white solid was then dried for 24 h at 120 C. and calcined for 5 h at 500 C. under air to afford 2.261 g of a white product.

(8) The N2 adsorption isotherm measurement indicated that the material had a Langmuir surface area of 625 m.sup.2/g.

(9) A scanning electron micrograph image of the resulting product taken at a magnification of 5,000:1 is shown in FIG. 1.

Example 2

Synthesis of Silicalite using Silicon Powder

(10) In a round bottom flask with a capacity of 250 ml and equipped with a reflux condenser and a gas bubbler, 2.1 g of silicon powder (325 mesh) were suspended in 170 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. overnight while conducting a light stream of nitrogen gas through the apparatus, during which the silicon dissolved. After complete dissolution which was signalized by no more gas formation being observed in the solution, a light grey hazy residue remained. The solution was then filtered by suction filtration over a paper filter, thus affording a solution having a pH of 14.9. The reaction mixture thus obtained displayed a pH of 15.27.

(11) 155.2 g of the solution were transferred to an autoclave, which was then heated to 170 C. and held at that temperature for 48 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was suction filtered over a filter paper and the solid was washed with 500 ml of distilled water. The white solid was then dried over night at 120 C. and calcined for 5 h at 500 C. under air to afford 1.56 g of a light brown product.

(12) The characterization of the final product by XRD as shown in FIG. 2 shows that the product has the MFI-type framework structure, as is apparent from the line pattern of ZSM-5 which has been included for comparison.

Example 3

Synthesis of Silicalite using Silicon Powder

(13) In a round bottom flask with a capacity of 250 ml and equipped with a reflux condenser and a gas bubbler, 4.14 g of silicon powder (325 mesh) were suspended in 170 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. overnight while conducting a light stream of nitrogen gas through the apparatus, during which the silicon dissolved. After complete dissolution which was signalized by no more gas formation being observed in the solution, a light grey hazy residue remained. The solution was then filtered by suction filtration over a paper filter, thus affording a solution having a pH of 14.9. The reaction mixture thus obtained displayed a pH of 14.9.

(14) 157.1 g of the solution were transferred to an autoclave, which was then heated to 170 C. and held at that temperature for 48 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was suction filtered over a filter paper and the solid was washed with 500 ml of distilled water. The white solid was then dried over night at 120 C. and calcined for 5 h at 500 C. under air to afford 5.01 g of a white product.

(15) Elemental Analysis: Si 45 wt.-%

(16) The characterization of the final product by XRD as shown in FIG. 3 shows that the product has the MFI-type framework structure, as is apparent from the line pattern of ZSM-5 which has been included for comparison.

Example 4

Synthesis of Silicalite using Silicon Powder

(17) The procedure according to Example 3 was repeated, wherein after preparing the synthesis gel, 151.5 g of the filtered solution were transferred to an autoclave, which was then heated to 170 C. and held at that temperature for 120 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was suction filtered over a filter paper and the solid was washed with 1 liter of distilled water. The white solid was then dried over night at 120 C. and calcined for 5 h at 500 C. under air to afford 7.19 g of a beige product.

(18) Elemental Analysis: Si 45 wt.-%

(19) The characterization of the final product by XRD as shown in FIG. 4 shows that the product has the MFI-type framework structure, as is apparent from the line pattern of ZSM-5 which has been included for comparison.

Example 5

Synthesis of ZSM-5 using Silicon and Aluminum Powders

(20) In a round bottom flask equipped with a reflux condenser and sealed with the aid of a gas bubbler, 2.1 g of silicon powder (325 mesh) and 86 mg of aluminum powder were suspended in 170 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. during 7 h, during which silicon dissolved until a light grey hazy residue remained in the solution. The solution was filtered prior to its transfer to an autoclave. The reaction mixture thus obtained displayed a pH of 15.30.

(21) The autoclave was heated to 170 C. and held at that temperature for 336 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was filtered and the solid was washed several times with water. The white solid was then dried for 24 h at 120 C. and calcined for 5 h at 500 C. under air to afford 1.823 g of a white product.

(22) The characterization of the final product by XRD as shown in FIG. 5A shows that the product has the MFI-type framework structure, as is apparent from the line pattern of ZSM-5 which has been included for comparison.

(23) A scanning electron micrograph image of the resulting product taken at a magnification of 5,000:1 is shown in FIG. 5B.

Example 6

Synthesis of TS-1 using Silicon and Titanium Powders

(24) In a round bottom flask equipped with a reflux condenser and sealed with the aid of a gas bubbler, 2.1 g of silicon powder (325 mesh) and 60 mg of titanium powder were suspended in 170 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. during 7 h, during which silicon dissolved until a light grey hazy residue remained in the solution. The solution was filtered prior to its transfer to an autoclave. The reaction mixture thus obtained displayed a pH of 15.9.

(25) The autoclave was heated to 170 C. and held at that temperature for 24 h. After cooling, a clear solution containing a white precipitate was obtained. The suspension was filtered and the solid was washed several times with water. The white solid was then dried for 24 h at 120 C. and calcined for 5 h at 500 C. under air to afford 1.728 g of a white product.

(26) Elemental Analysis: Si 44 wt.-% Ti 0.9 wt.-%

(27) The characterization of the final product by XRD as shown in FIG. 6A shows that the product has the MFI-type framework structure, as is apparent from the line pattern of TS-1 which has been included for comparison.

(28) A scanning electron micrograph image of the resulting product taken at a magnification of 5,000:1 is shown in FIG. 6B.

Example 7

Synthesis of TS-1 using Silicon Powder and Tetraethylorthotitanate

(29) In a round bottom flask with a capacity of 250 ml and equipped with a reflux condenser and a gas bubbler, 4.14 g of silicon powder (325 mesh) were suspended in 161.3 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. overnight while conducting a light stream of nitrogen gas through the apparatus, during which the silicon dissolved. After complete dissolution which was signalized by no more gas formation being observed in the solution, a light grey hazy residue remained. The solution was then filtered by suction filtration over a paper filter.

(30) 8.49 g of aqueous tetrapropylammonium hydroxide (40%) were placed in a beaker and 2.7 g tetraethylorthotitanate were added thereto while stirring the mixture. Initially, white flocks formed in the mixture, which then dissolved to afford a clear solution after about 1.5 h.

(31) The solutions were then united and stirred for 10 min, the reaction mixture thus obtained displaying a pH of 14.8. 148.5 g of the resulting solution were transferred to an autoclave, which was then heated to 170 C. and held at that temperature for 48 h. After cooling, a clear solution containing a grey precipitate was obtained. The suspension was diluted to twice its volume with water and subsequently neutralized to pH=7 using about 300 g of 5% nitric acid. During neutralization of the suspension a gel starts to form at around pH=11 to afford a thick suspension which was suction filtered over a filter paper and the solid was washed with distilled water. The solid was then dried over night at 120 C. and calcined for 5 h at 500 C. under air to afford 8.11 g of a white product.

(32) Elemental Analysis: Si 41 wt.-% Ti 6 wt.-%

(33) The characterization of the final product by XRD as shown in FIG. 7 shows that the product has the MFI-type framework structure, as is apparent from the line pattern of TS-1 which has been included for comparison.

(34) Conversion into the H-Form:

(35) In a round bottom flask with a capacity of 250 ml and equipped with a reflux condenser, 80 g of an aqueous solution of diluted nitric acid (10%) were placed, to which 4 g of the calcined product were added. The resulting mixture was then stirred for 1 h under refluxing of the solution. The resulting white suspension was cooled, and the zeolite material filtered off and washed four times with 250 ml of distilled water. The filter cake was dried over night at 120 C., and then calcined for 5 h at 650 C. under air, thus affording 3.66 g of a white crystalline product.

(36) Propylene Oxide Test:

(37) In the catalytic activity test, 0.5 g of titanium zeolite TS-1 in the H-Form prepared as described above were introduced together with 45 ml of methanol into a glass pressure-proof reactor, and 20 ml of propene were introduced at 0 C. 18 g of hydrogen peroxide (Merck, 30% by weight in water) were subsequently fed in by means of a pump. After a reaction time of 5 hours, the mixture was depressurized and the liquid phase was analyzed by gas chromatography. The reaction mixture contained 1.52% by weight of propylene oxide.

Example 8

Synthesis of Bor-ZSM-5 using Silicon and Boric Acid

(38) In a round bottom flask with a capacity of 250 ml and equipped with a reflux condenser and a gas bubbler, 4.14 g of silicon powder (325 mesh) were suspended in 161.3 g of an aqueous solution of tetrapropylammonium hydroxide (40%). The black suspension was stirred and heated to 50 C. overnight while conducting a light stream of nitrogen gas through the apparatus, during which the silicon dissolved. After complete dissolution which was signalized by no more gas formation being observed in the solution, a light grey hazy residue remained. The solution was then filtered by suction filtration over a paper filter.

(39) 8.49 g of aqueous tetrapropylammonium hydroxide (40%) were placed in a beaker and 0.73 g of boric acid was added thereto while stirring the mixture. The mixture was then further stirred to obtain a clear solution after 30 min.

(40) The solutions were then united and stirred for 10 min, the reaction mixture thus obtained displaying a pH of 14.7. 151.9 g of the resulting solution were transferred to an autoclave, which was then heated to 170 C. and held at that temperature for 48 h. After cooling, a clear solution containing a grey precipitate was obtained. The suspension was diluted to twice its volume with water and subsequently neutralized to pH=7 using about 310 g of 5% nitric acid. During neutralization of the suspension a gel starts to form at around pH=8 to afford a thick Suspension which was suction filtered over a filter paper and the solid was washed with distilled water. The solid was then dried over night at 120 C. and calcined for 5 h at 500 C. under air to afford 7.49 g of a white product.

(41) Elemental Analysis: Si 45 wt.-% B 0.17 wt.-%

(42) The characterization of the final product by XRD as shown in FIG. 8 shows that the product has the MFI-type framework structure, as is apparent from the line pattern of TS-1 which has been included for comparison.