Post-treatment of a zeolitic material

Abstract

A process for the post-treatment of a zeolitic material, the process comprising (i) providing a zeolitic material, wherein the framework structure of the zeolitic material comprises YO.sub.2 and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element; (ii) subjecting the zeolitic material provided in (i) to a method comprising (a) treating the zeolitic material with an aqueous solution having a pH of at most 5, (b) treating the zeolitic material obtained from (a) with a liquid aqueous system having a pH in the range of 5.5 to 8 and a temperature of at least 75 C.; wherein in (ii) and after (b), the zeolitic material is optionally subjected to at least one further treatment according to (a) and/or at least one further treatment according to (b).

Claims

1. A process for a post-treatment of a zeolitic material, the process comprising: (i) providing the zeolitic material, wherein the zeolitic material has a framework structure comprising YO.sub.2 and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element, and wherein Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and any combination thereof, and wherein X is selected from the group consisting of Al, B, In, Ga, Fe and any combination thereof; (ii) subjecting the zeolitic material to a method comprising (a) treating the zeolitic material with an acidic aqueous solution having a pH of at most 5, wherein the aqueous solution comprises at least one of an organic acid and an inorganic acid; and (b) treating the zeolitic material obtained from (a) with a liquid aqueous system having a pH of ranging from 5.5 to 8 and at a temperature of at least 75 C., wherein the liquid aqueous system comprises at least 90 weight-% water, wherein neither in (i) nor in (ii), the zeolitic material is subjected to water stream treatment wherein the pH of the aqueous solution according to (a) and the pH of the liquid aqueous system according to (b) is determined using a pH sensitive glass electrode.

2. The process of claim 1, wherein the method according to (ii) comprises: (a) treating the zeolitic material with the acidic aqueous solution having a pH of at most 5; (b) treating the zeolitic material obtained from (a) with a liquid aqueous system having a pH ranging from 5.5 to 8 and at a temperature of at least 75 C.; and (c) treating the zeolitic material obtained from (b) with the acidic aqueous solution having a pH of at most 5.

3. The process of claim 2, wherein after (a), the zeolitic material is subjected to a treatment with a liquid aqueous system having a pH ranging from 5.5 to 8 and at a temperature of less than 75 C.

4. The process of claim 1, wherein in (a), the acidic aqueous solution comprises one or more of an organic acid selected from the group consisting of oxalic acid, acetic acid, citric acid, methane sulfonic acid, and any mixture thereof, and of an inorganic acid selected from the group consisting of phosphoric acid, sulphuric acid, hydrochloric acid, nitric acid, and any mixture thereof.

5. The process of claim 1, wherein in (a), the acidic aqueous solution has a pH ranging from 0 to 5.

6. The process of claim 1, wherein in (a), the zeolitic material is treated with the acidic aqueous solution at a temperature ranging from 20 C. to 100 C.

7. The process of claim 1, wherein in (a), the zeolitic material is treated with the acidic aqueous solution for a period ranging from 10 min to 12 h.

8. The process of claim 1, wherein in (b), the zeolitic material is treated with the liquid aqueous system at a temperature ranging from 80 C. to 180 C.

9. The process of claim 1, wherein in (b), the zeolitic material is treated with the liquid aqueous system for a period ranging from 0.5 h to 24 h.

10. The process of claim 1, wherein in (b), a weight ratio of the liquid aqueous system relative to the zeolitic material ranges from 20:1 to 2:1.

11. The process of claim 1, wherein in (b), the liquid aqueous system comprises at least 99 weight-% water.

12. The process of claim 1, wherein in (ii) and after (b), the zeolitic material is subjected to one or more of drying and calcination.

13. The process of claim 1, wherein Y is Si, and wherein X is Al.

14. The process of claim 1, wherein one or more of the acidic aqueous solution according to (a) and of the liquid aqueous system according to (b) comprise one or more of at least one salt of at least one organic acid and of at least one salt of at least one inorganic acid.

15. The process of claim 14, wherein the at least one salt is an ammonium salt and the zeolitic material provided in (i) is in a sodium form.

16. The process of claim 1, wherein (i) comprises an organotemplate-free synthetic method comprising (1) preparing a mixture comprising seed crystals and at least one source for YO.sub.2 and at least one source for X.sub.2O.sub.3, and (2) crystallizing the zeolitic material from the mixture, wherein the seed crystals comprise zeolitic material having the framework structure of the zeolitic material.

17. The process of claim 1, wherein the zeolitic material in (i) has a LEV, CHA, MFI, MWW, BEA framework structure.

18. The process of claim 1, wherein neither in (i) nor in (ii) nor after (ii), the zeolitic material is subjected to water steam treatment.

19. A zeolitic material, having a framework structure which comprises YO.sub.2 and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element, wherein Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge and any combination thereof, wherein X is selected from the group consisting of Al, B, In, Ga, Fe and any combination thereof, wherein the zeolitic material is characterized by a IR spectrum exhibiting a first absorption band with a maximum in a range of from 3730 cm.sup.1 to 3750 cm.sup.1 and a second absorption band with a maximum in a range of from 3600 cm.sup.1 to 3700 cm.sup.1, wherein a ratio of a peak height of the second absorption band relative to a peak height of the first absorption band is in a range of from 0.1 to 0.9.

20. The zeolitic material of claim 19, wherein a YO.sub.2 : X.sub.2O.sub.3 molar ratio is in a range of from 20:1 to 60:1.

21. The zeolitic material of claim 19, wherein a water uptake of the zeolitic material is at most 20 weight-%.

22. The zeolitic material of claim 19, wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is in a range of from 0.2 to 0.8.

23. The zeolitic material of claim 19, wherein Y is Si, and wherein X is Al.

24. The zeolitic material of claim 19, having a LEV, CHA, MFI, MWW, BEA framework structure.

25. The zeolitic material of claim 19, wherein Y is Si and X is Al, and the zeolitic material is dealuminated zeolite Beta.

26. A zeolitic material obtained by the process of claim 1.

Description

EXAMPLES

Reference Example 1

Determination of the Water Uptake

(1) Water adsorption/desorption isotherms were performed on a VTI SA instrument from TA Instruments following a step-isotherm program. The experiment consisted of a run or a series of runs performed on a sample material that has been placed on the microbalance pan inside of the instrument. Before the measurement was started, the residual moisture of the sample was removed by heating the sample to 100 C. (heating ramp of 5 C./min) and holding it for 6 h under a nitrogen flow. After the drying program, the temperature in the cell was decreased to 25 C. and kept isothermal during the measurement. The microbalance was calibrated, and the weight of the dried sample was balanced (maximum mass deviation 0.01 wt.-%). Water uptake by the sample was measured as the increase in weight over that of the dry sample. First, as adsorption curve was measured by increasing the relative humidity (RH) (expressed as wt.-% water in the atmosphere inside of the cell) to which the sample was exposed and measuring the water uptake by the sample as equilibrium. The RH was increased with a step of 10 wt.-% from 5% to 85% and at each step the system controlled the RH and monitored the sample weight until reaching the equilibrium conditions after the sample was exposed from 85 wt.-% to 5 wt.% with a step of 10% and the change in the weight of the sample (water uptake) was monitored and recorded.

Reference Example 2

Determination of the Crystallinity

(2) The crystallinity of the zeolitic materials according to the present invention was determined by XRD analysis, wherein the crystallinity of a given material is expressed relative to a reference zeolitic material wherein the reflecting surfaces of the two zeolitic materials are compared. The reference zeolitic material was zeolite ammonium beta powder commercially available from Zeolyst International, Valley Forge, Pa. 19482, USA, under the tradename CP814C, CAS Registry Number 1318-02-1, wherein this powder was further calcined under air for 5 h at 500 C. (heating ramp 1 C./min). The determination of the crystallinities were performed on a D8 Advance series 2 diffractometer from Bruker AXS. The diffractometer was configured with an opening of the divergence aperture of 0.1 and a Lynxeye detector. The samples as well as the reference zeolitic material were measured in the range from 19 to 25 (2 Theta). After baseline correction, the reflecting surfaces were determined by making use of the evaluation software EVA (from Bruker AXS). The ratios of the reflecting surfaces are given as percentage values.

Reference Example 3

IR Measurements

(3) The IR measurements were performed on a Nicolet 6700 spectrometer. The zeolitic materials were pressed into a self-supporting pellet without the use of any additives. The pellet was introduced into a high vacuum cell placed into the IR instrument. Prior to the measurement the sample was pretreated in high vacuum (10.sup.5 mbar) for 3 h at 300 C. The spectra were collected after cooling the cell to 50 C. The spectra were recorded in the range of 4000 cm.sup.1 to 800 cm.sup.1 at a resolution of 2 cm.sup.1. The obtained spectra were represented by a plot having on the x axis the wavenumber (cm.sup.1) and on the y axis the absorbance (arbitrary units). For the quantitative determination of the peak heights and the ratio of the peak heights, a baseline correction was carried out. Changes in the 3000 cm.sup.1 to 3900 cm.sup.1 region were analyzed and for comparing multiple samples, the band at 18005 cm.sup.1 was taken as reference.

Reference Example 4

Preparation of the Starting Materials (Zeolitic Materials)

(4) a) 1000 g zeolitic material prepared according to b) were added to 10 g of a 10 weight-% solution of ammonium nitrate. The suspension was heated to 80 C. and kept at this temperature under continuous stirring for 2 h. The solid was filtered hot (without additional cooling) over a filter press. The filter cake was then washed with distilled water (room temperature wash water) until the conductivity of the wash water was below 200 microSiemens/cm. The filter cake was dried for 16 h at 120 C. This procedure was repeated once, affording ion exchanged crystalline product BEA in its ammonium form. A following calcination step at 500 C. for 5 h (heat ramp 1 C./min) afforded ion exchanged crystalline product BEA in its H-form. b) 335.1 g of NaAlO.sub.2 were dissolved in 7314 g of H.sub.2O while stirring, followed by addition of 74.5 g of zeolite Beta seeds (commercially available from Zeolyst International, Valley Forge, Pa. 19482, USA, under the tradename CP814C, CAS Registry Number 1318-02-1). The mixture was placed in a 20 L autoclave and 7340 g sodium waterglass and 1436 g Ludox AS40 were added. Crystallization of the obtained aluminosilicate gel took place at 120 C. for 117 h. After having let the reaction mixture cool to room temperature, the solid was separated by filtration, repeatedly washed with distilled water and then dried at 120 C. for 16 h. The resulting material had a water uptake of 12 weight-%.

Comparative Example 1

Dealumination of a Zeolitic Material Without Treatment with a Liquid Aqueous System

(5) First Acidic Dealumination

(6) 300 g of a 4 weight-% HNO.sub.3aqueous solution, having a pH in the range of from 0 to 1, were provided in a vessel, and 100 g zeolitic material having a BEA framework structure, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 10.79: 1 and a crystallinity of 78% as prepared according to Reference Example 4 a) were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14.80: 1, a crystallinity of 72% and a water uptake of 13.9 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.37 at 3741 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.37 at 3659 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 1.01. This zeolitic material was subjected to a second acidic dealumination.

(7) Second Acidic Dealumination

(8) 273 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 91 g zeolitic material obtained from the first acidic dealumination were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21.08:1, a crystallinity of 72% and a water uptake of 15.9 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.37 at 3741 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.20 at 3663 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.521. This zeolitic material was subjected to a third acidic dealumination treatment.

(9) Third Acidic Dealumination

(10) 237 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 79 g zeolitic material obtained from the second acidic dealumination were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 40.00:1, a crystallinity of 50%, and a water uptake of 14.3 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.95 at 3741 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.54 at 3626 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.565.

(11) Result of the Comparative Experiment

(12) By the acidic treatments as described above, the SiO.sub.2:Al.sub.2O.sub.3 molar ratio of the zeolitic material was increased from 10.79:1 to 40:1. However, the crystallinity of the zeolitic material significantly deteriorated from an initial value of 78% to a final value of 50%.

(13) Therefore, the acidic dealumination process resulted in a loss of crystallinity of 36%. In particular, the crystallinity of the zeolitic material starts to deteriorate significantly (i.e., from 72% to 50%) after the third acidic dealumination. Besides that, after first decreasing after the first second acidic dealumination, the ratio of the peak height of the second IR absorption band relative to the peak height of the first IR absorption band starts to increase, indicating an increase in the relative concentration of the internal defects (i.e., silanol nests).

Example 1

Dealumination with Treatment with a Liquid Aqueous System

(14) First Acidic Dealumination

(15) 300 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 100 g zeolitic material having a BEA framework structure, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 10.79: 1 and a crystallinity of 78% as prepared according to Reference Example 4 a) were added (the same zeolitic material was employed as in Comparative Example 1).

(16) The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried by heating at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14.58:1, a crystallinity of 73% and a water uptake of 14.4 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.37 at 3741 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.37 at 3659 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 1.01. This zeolitic material was subjected to a first treatment with a liquid aqueous system.

(17) First Treatment with a Liquid Aqueous System

(18) 750 g de-ionized water and 85 g zeolitic material obtained from the first acidic dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension, the zeolitic material was separated by filtration. The obtained zeolitic material was dried at 120 C. for 16 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14.80:1, a crystallinity of 75% and a water uptake of 12 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.36 at 3732 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.26 at 3617 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.730. This zeolitic material was subjected to a second acidic dealumination.

(19) Second Acidic Dealumination

(20) 240 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 80 g zeolitic material obtained from the first treatment with a liquid aqueous system were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 21.62: 1, a crystallinity of 73% and a water uptake of 15.7 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.29 at 3736 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.18 at 3668 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.621. This zeolitic material was subjected to a second treatment with liquid aqueous system.

(21) Second Treatment with a Liquid Aqueous System

(22) 750 g de-ionized water and 67 g zeolitic material obtained from the second acidic dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material was dried at 120 C. for 16 h. The obtained zeolitic material had a SiO.sub.2: l.sub.2O.sub.3 molar ratio of 21.39: 1, a crystallinity of 78% and a water uptake of 14.8 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.74 at 3734 cm.sup.1) and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.31 at 3663 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.418. This zeolitic material was subjected to a third acidic dealumination.

(23) Third Acidic Dealumination

(24) 195 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 65 g zeolitic material obtained from the second treatment with a liquid aqueous system were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (heat ramp 1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 36.52: 1, a crystallinity of 98% and a water uptake of 17.3 weight-%. Moreover, the IR spectrum of the obtained product exhibits a first absorption band with the maximum in the range of from 3730 to 3750 cm.sup.1 (absorbance intensity of 0.37 at 3743 cm.sup.1)and a second absorption band with the maximum in the range of from 3600 to 3700 cm.sup.1 (absorbance intensity of 0.14 at 3658 cm.sup.1), wherein the ratio of the peak height of the second absorption band relative to the peak height of the first absorption band is 0.383.

(25) Results of Example 1

(26) As in the Comparative Example 1, three acidic dealumination steps were carried out in Example 1. As in the Comparative Example 1, the SiO.sub.2:Al.sub.2O.sub.3 molar ratio was increased from the starting value of 10.79:1 to a value of 36.52:1 which is about the same as the value obtained in Comparative Example 1 (40:1). However, contrary to the process according to Comparative Example 1, the crystallinity of the zeolitic material did not decrease. Quite to the contrary, the intermediate treatments with a liquid aqueous system according to the invention even resulted in an increase in crystallinity from the starting value of 78% to the final value of 98%.

(27) Moreover, although two treatments with a liquid aqueous systems were performed, the water uptake of the zeolitic material which characterizes the hydrophobicity of the zeolitic material and, thus, an important chemical parameter of the zeolitic material, did not change significantly (12 weight-% of the starting material, 14.4 weight-% for the material after the first acidic treatment, 17.3 weight-% of the product).

(28) Furthermore, concerning the ratio of the peak height of the second IR absorption band relative to the peak height of the first IR absorption band, said ratio decreases continuously during the above process for the preparation of Example 1, indicating that the relative concentration of internal defects (i.e., silanol nests) is decreased continuously by the inventive process comprising steps (ii)(a) and (ii)(b) as defined in claim 1. Such an increase of crystallinity and a decrease of internal defects during the leaching of Al out of the zeolitic material are entirely unexpected, especially in view of Comparative Example 1 wherein a conventional dealumination process leads to a deterioration the crystal quality, in particular with respect to the crystallinity as well as with respect to the concentration of internal defects, in particular when obtaining products with higher YO.sub.2 : X.sub.2O.sub.3 molar ratios.

Example 2

Dealumination with Treatment with a Liquid Aqueous System Without Calcination

(29) First Acidic Dealumination

(30) 300 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 100 g zeolitic material having a BEA framework structure, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 10.79: 1 and a crystallinity of 78% as prepared according to Reference Example 4 a) were added (the same zeolitic material was employed as in Comparative Example 1 and in Example 1).

(31) The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried under vacuum. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 13.49:1 and a water uptake of 14.6 weight-%. This zeolitic material was subjected to a first treatment with a liquid aqueous system.

(32) First Treatment with a Liquid Aqueous System 750 g de-ionized water and the dried zeolitic material obtained from the first acidic dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material had a water uptake of 12.5 weight-%. This zeolitic material was subjected to a second acidic dealumination.
Second Acidic Dealumination

(33) 192 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 64 g zeolitic material obtained from the first treatment with a liquid aqueous system were added. The suspension was stirred at 200 rpm (rounds per minute) for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h. The obtained zeolitic material had a SiO.sub.2: Al.sub.2O.sub.3 molar ratio of 19.72:1 and a water uptake of 18.9 weight-%. This zeolitic material was subjected to a second treatment with a liquid aqueous system.

(34) Second Treatment with a Liquid Aqueous System

(35) 750 g de-ionized water and 54 g zeolitic material obtained from the second acidic dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 20.08:1, a crystallinity of 79% and a water uptake of 12.5 weight-%

(36) Results of Example 2

(37) As Example 1, also Example 2 shows that the inventive treatment with a liquid aqueous system as step in a dealumination process, allows the SiO.sub.2:Al.sub.2O.sub.3 molar ratio to be increased (from 10.79:1 to 20.08:1) and, simultaneously, to increase the crystallinity of the zeolitic material (from 78% to 79%).

(38) Moreover, although two treatments with a liquid aqueous systems were performed, the water uptake of the zeolitic material which characterizes the hydrophobicity of the zeolitic material and, thus, an important chemical parameter of the zeolitic material, did not change significantly (12 weight-% of the starting material, 14.6 weight-% for the material after the first acidic treatment, 12.5 weight-% of the product).

Example 3

Large Scale Experiment with Increasing Acid Strength

(39) First Acidic Dealumination

(40) 51.45 kg of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel, equipped with a disk-type stirrer, and 17.15 kg zeolitic material having a BEA framework structure, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 10.79:1 and a crystallinity of 78% as prepared according to Reference Example 4 a) were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was cooled to 50 C., filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 14.49:1. This zeolitic material was subjected to a first treatment with a liquid aqueous system.

(41) First Treatment with a Liquid Aqueous System

(42) 127 kg de-ionized water and 15.89 kg zeolitic material obtained from the first acidic dealumination were provided in a vessel, equipped with a propeller stirrer. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material was dried at 120 C. for 68 h. This zeolitic material was subjected to a second acidic dealumination.

(43) Second Acidic Dealumination

(44) 46.61 kg of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel, equipped with a disk-type stirrer, and 15.54 kg zeolitic material obtained from the first treatment with a liquid aqueous system were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was cooled to 50 C., filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 48 h and calcined by heating to 600 C. (1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 19.73:1. This zeolitic material was subjected to a second treatment with a liquid aqueous system.

(45) Second Treatment with a Liquid Aqueous System

(46) 116 kg de-ionized water and 14.48 kg g zeolitic material obtained from the second acidic dealumination were provided in a vessel, equipped with a propeller stirrer. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material was dried at 120 C. for 22 h. This zeolitic material was subjected to a third acidic dealumination.

(47) Third Acidic Dealumination

(48) 40.95 kg of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel, equipped with a disk-type stirrer, and 13.65 kg zeolitic material obtained from the second treatment with a liquid aqueous system were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was cooled to 50 C., filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm.

(49) The obtained zeolitic material was dried at 120 C. for 68 h and calcined by heating to 600 C. (1 C. per minute) and then heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 31.53:1. This zeolitic material was subjected to a third treatment with a liquid aqueous system.

(50) Third Treatment with a Liquid Aqueous System

(51) 103 kg de-ionized water and 12.82 kg g zeolitic material obtained from the third acidic dealumination were provided in a vessel, equipped with a propeller stirrer. The suspension was heated to 90 C. and stirred for 9 h. From this suspension zeolitic material was separated by filtration. The obtained zeolitic material was dried at 120 C. for 22 h. This zeolitic material was subjected to a fourth acidic dealumination.

(52) Fourth Acidic Dealumination

(53) 38.16 kg of a 8 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel, equipped with a disk-type stirrer, and 12.72 kg zeolitic material obtained from the third treatment with a liquid aqueous system were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was cooled to 50 C., filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 25 h and calcined by heating to 600 C. (1 C. per minute) and then heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 46.67: 1 and a crystallinity of 82%.

(54) Results of Example 3

(55) As Examples 1 and 2, also Example 3, carried out as a large-scale experiment and, thus, under different conditions, shows that the inventive treatment with a liquid aqueous system as step in a dealumination process, allows the SiO.sub.2:Al.sub.2O.sub.3 molar ratio to be increased (from 10.79:1 to 46.67:1) and, simultaneously, to increase the crystallinity of the zeolitic material (from 78% to 82%). It must be emphasized that the crystallinity was increased by the inventive process, although the SiO.sub.2:Al.sub.2O.sub.3 molar ratio was increased for a factor of about 5 and, thus, increased for a factor larger than the respective factor according to the Comparative Example 1 (about 4) where a significant decrease of the crystallinity was observed.

Example 4

Dealumination with Treatment with a Liquid Aqueous System, Including Treatment with Salt of an Inorganic Acid

(56) First Acidic Dealumination

(57) 200 g NH.sub.4NO.sub.3 were dissolved in 600 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, and 200 g zeolitic material having a BEA framework structure, a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 9.68:1, a Na.sup.+ content of 5.1% and a crystallinity of 72% as prepared according to Reference Example 4 b) were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 13.21:1 and a Na.sup.+ content of 0.36%. This zeolitic material was subjected to a first treatment with a liquid aqueous system.

(58) First Treatment with a Liquid Aqueous System

(59) 1500 g de-ionized water and 160 g zeolitic material from the second acid dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension the zeolitic material was separated by filtration and dried at 120 C. for 12 h. This zeolitic material was subjected to a second acidic dealumination.

(60) Second Acidic Dealumination

(61) 160 g NH.sub.4NO.sub.3 were dissolved in 480 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, and 160 g zeolitic material obtained from the second treatment with a liquid aqueous system were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 20.81:1 and a Na.sup.+ content of 0.01%. This zeolitic material was subjected to a second treatment with a liquid aqueous system.

(62) Second Treatment with a Liquid Aqueous System

(63) 1500 g de-ionized water and 140 g zeolitic material obtained from the second acid dealumination were provided in a vessel. The suspension was heated to 90 C. and stirred for 9 h. From this suspension the zeolitic material was separated by filtration and dried at 120 C. for 12 h. This zeolitic material was subjected to a third acidic dealumination.

(64) Third Acidic Dealumination

(65) 420 g of a 4 weight-% HNO.sub.3 aqueous solution, having a pH in the range from 0 to 1, were provided in a vessel and 140 g zeolitic material obtained from the second treatment with a liquid aqueous system were added. The suspension was stirred for 2 h at a temperature of 60 C. The suspension was filtered and the filter cake was then washed with de-ionized water at room temperature until the washing water had a conductivity of less than 200 microSiemens/cm. The obtained zeolitic material was dried at 120 C. for 16 h and calcined by heating to 600 C. (1 C. per minute) and subsequent heating at 600 C. for 5 h. The obtained zeolitic material had a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of 30.77:1, a Na.sup.+ content of 0.01% and a crystallinity of 75%.

(66) Results of Example 4

(67) As Examples 1, 2 and 3, also Example 4 shows that the inventive treatment with a liquid aqueous system as step in a dealumination process, allows the SiO.sub.2:Al.sub.2O.sub.3 molar ratio to be increased (from 9.68:1 to 30.77: 1) and, simultaneously, to increase the crystallinity of the zeolitic material (from 72% to 75%).

(68) Moreover, Example 4 shows that the inventive treatment allows a simultaneous ion exchange. The treatment with a aqueous solution comprising NH.sub.4NO.sub.3 according to Example 4 leads to a significant decrease of the Na.sup.+ content in the zeolitic material (from 5.1% to 0.01%) by exchange of the Na.sup.+ ions with NH.sub.4.sup.+ ions.

SUMMARY OF THE EXAMPLES

(69) As shown in the Comparative Example and the Examples according to the invention, the process of the present invention is highly advantageous for processes wherein the YO.sub.2:X.sub.2O.sub.3 molar ratio, in particular the SiO.sub.2:Al.sub.2O.sub.3 molar ratio of a zeolitic material is to be increased since the crystallinity of the zeolitic material, a significant feature of the zeolitic material, can be increased. No matter if the experiments were carried out in laboratory scale or industrial scale, and irrespective of the factor by which the YO.sub.2:X.sub.2O.sub.3 molar ratio, in particular the SiO.sub.2:Al.sub.2O.sub.3 molar ratio is increased: the inventive treatment with a liquid aqueous system allows the crystallinity of the zeolitic material thus treated to be kept constant or even increased.

CITED LITERATURE

(70) EP 0 013 433 A1 WO 02/057181 A2 WO 2009/016153 A2