CHA type zeolitic materials and methods for their preparation using combinations of cycloalkyl-and tetraalkylammonium compounds

Abstract

The present invention relates to a process for the preparation of a zeolitic material having a CHA-type framework structure comprising YO.sub.2 and X.sub.2O.sub.3, wherein said process comprises the steps of: (1) providing a mixture comprising one or more sources for YO.sub.2, one or more sources for X.sub.2O.sub.3, one or more tetraalkylammonium cation R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+-containing compounds, and one or more tetraalkylammonium cation R.sup.5R.sup.6R.sup.7R.sup.8N.sup.+-containing compounds as structure directing agent; (2) crystallizing the mixture obtained in step (1) for obtaining a zeolitic material having a CHA-type framework structure; wherein Y is a tetravalent element and X is a trivalent element, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, and R.sup.7 independently from one another stand for alkyl, and wherein R.sup.8 stands for cycloalkyl, as well as to zeolitic materials which may be obtained according to the inventive process and to their use.

Claims

1. A process for the preparation of a zeolitic material having a CHA-type framework structure comprising SiO.sub.2 and Al.sub.2O.sub.3, wherein said process comprises the steps of: (1) providing a mixture comprising one or more sources for SiO.sub.2, one or more sources for Al.sub.2O.sub.3, one or more tetramethylammonium compounds, and one or more N,N,N-trimethyl-cyclohexylammonium compounds as structure directing agent; (2) crystallizing the mixture obtained in step (1) for obtaining the zeolitic material having a CHA-type framework structure; wherein the molar ratio of tetramethylammonium compounds to N,N,N-trimethyl-cyclohexylammonium compounds is comprised in the range from 0.45 to 0.65.

2. The process of claim 1, wherein the crystallization in step (2) is conducted under solvothermal conditions.

3. The process of claim 1, wherein the mixture provided in step (1) does not contain any substantial amount of a trimethyl benzyl ammonium containing compound.

4. The process of claim 1, wherein the mixture provided in step (1) further comprises seed crystals.

5. A synthetic zeolitic material having a CHA-type framework structure prepared by the process of claim 1.

6. A synthetic zeolitic material having a CHA-type framework structure, prepared by the process of claim 1, wherein the CHA-type framework structure comprises SiO.sub.2 and Al.sub.2O.sub.3, and wherein the IR-spectrum of the zeolitic material includes: a first absorption band (B1) in the range of from 3,720 to 3,740 cm.sup.?1; and a second absorption band (B2) in the range of from 1,850 to 1,890 cm.sup.?1; wherein the ratio of the maximum absorbance of the first absorption band to the second absorption band B1:B2 is in the range of from 0.5 to 1.55.

7. The zeolitic material of claim 6, wherein the particle size D10 of the zeolitic material is comprised in the range of from 400 to 2500 nm.

8. The zeolitic material of claim 6, wherein the average particle size D50 of the zeolitic material is comprised in the range of from 600 to 3500 nm.

9. The zeolitic material of claim 6, wherein the particle size D90 of the zeolitic material is comprised in the range of from 1200 to 4,500 nm.

10. The zeolitic material of claim 6, wherein the CHA-type framework contains 5 wt.-% or less of the elements P and/or As based on 100 wt-% of SiO.sub.2 contained in the framework structure.

11. The zeolitic material of claim 6, wherein the .sup.29Si MAS NMR of the zeolitic material includes: a first peak (P1) in the range of from ?102.0 to ?106.0 ppm; and a second peak (P2) in the range of from ?108.0 to ?112.5 ppm, wherein the integration of the first and second peaks in the .sup.29Si MAS NMR of the zeolitic material offers a ratio of the integration values P1:P2 comprised in the range of from 0.05 to 0.90.

12. The zeolitic material of claim 6, wherein the SiO.sub.2:Al.sub.2O.sub.3 molar ratio ranges from 4 to 200.

13. The synthetic zeolitic material of claim 6, wherein the material is an adsorbent material, an ion-exchange material, a catalyst or a catalyst support.

14. A synthetic zeolitic material having a CHA-type framework structure, prepared by the process of claim 1, wherein the CHA-type framework structure comprises SiO.sub.2 and Al.sub.2O.sub.3, and wherein the IR-spectrum of the zeolitic material includes: a first absorption band (B1) in the range of from 3,720 to 3,740 cm.sup.?1; and a second absorption band (B2) in the range of from 1,850 to 1,890 cm.sup.?1; wherein the ratio of the maximum absorbance of the first absorption band to the second absorption band B1:B2 is in the range of from 0.5 to 1.55; wherein the particle size D10 of the zeolitic material is in a range of from 400 to 2500 nm, the average particle size D50 of the zeolitic material is in a range of from 600 to 3500 nm, and the particle size D90 of the zeolitic material is in a range of from 1200 to 4,500 nm, and a .sup.29Si MAS NMR spectrum of the zeolitic material includes: a first peak (P1) in the range of from ?102.0 to ?106.0 ppm; and a second peak (P2) in the range of from ?108.0 to ?112.5 ppm, wherein the integration of the first and second peaks in the .sup.29Si MAS NMR of the zeolitic material offers a ratio of the integration values P1:P2 comprised in the range of from 0.05 to 0.90.

Description

DESCRIPTION OF THE FIGURES

(1) FIGS. 1 to 6 display the IR-spectra obtained for the crystalline material obtained according to Examples 2 and 3, and Comparative Examples 1, 2, 3, and 4, respectively. In the figures, the wavenumbers in cm.sup.?1 is shown along the abscissa, and the absorbance is plotted along the ordinate.

(2) FIG. 7 displays the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the reaction product obtained according to Comparative Example 5. For comparative purposes, the line pattern of the CHA type structure is indicated in the diffractogram of the amorphous material as a reference. In the figure, the angle 2 theta in ? is shown along the abscissa and the intensities are plotted along the ordinate.

(3) FIG. 8 displays the X-ray diffraction pattern (measured using Cu K alpha-1 radiation) of the reaction product obtained according to Comparative Example 6. In an attempt to identify the reaction product, the line patterns of the hydrogen sodium aluminum silicate structure (H.sub.1.98Na.sub.0.02Al.sub.2Si.sub.50O.sub.104), of the quartz structure, and of the CHA type structure are indicated in the diffractogram of the amorphous material as a reference. In the figure, the angle 2 theta in ? is shown along the abscissa and the intensities are plotted along the ordinate.

EXAMPLES

(4) X-ray diffraction experiments on the powdered materials were performed using an Advance D8 Series 2 Diffractometer (Bruker/AXS) equipped with a Sol-X detector using the Cu K alpha-1 radiation.

(5) .sup.27Al MAS solid-state NMR experiments were measured by direct excitation with 15?-pulse under 10 kHz Magic Angle Spinning using 250 ms recycle delay and 20 ms acquisition. The data was processed with 50 Hz exponential line broadening.

(6) .sup.29Si MAS solid-state NMR experiments were performed using a Bruker Avance spectrometer with 300 MHz .sup.1H Larmor frequency (Bruker Biospin, Germany). Spectra were processed using Bruker Topspin with 30 Hz exponential line broadening, manual phasing, and manual baseline correction over the full spectrum width. Spectra were referenced with the polymer Q8M8 as an external secondary standard, by setting the resonance of the trimethylsilyl M group to 12.5 ppm.

(7) The IR-spectra were obtained from samples free of a carrier material, wherein said sample were heated at 300? C. in high vacuum for 3 h prior to measurement. The measurements were performed using a Nicolet 6700 spectrometer in a high vacuum measurement cell with CaF.sub.2 windows. The obtained data was transformed to absorbance values, and the analysis was performed on the spectra after base line correction.

(8) The particle size distribution of the samples was performed by dispersing 0.1 g of the zeolite powder in 100 g H.sub.2O and treating by ultrasound for 10 minutes. The dynamic light scattering was performed on a Zetasizer Nano ZS with the Malvern Zeta Sizer Software, Version 634, applying 5 runs ? 10 second measurement time for each sample. The given values are the average particle size by number in nanometer.

Example 1: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Trimethylcyclohexylammonium and Tetramethylammonium

(9) 692.01 g N,N,N-trimethylcyclohexylammonium hydroxide (20 wt-% solution in H.sub.2O) were mixed with 56.54 g of aluminiumtriisopropylate and 150.62 g tetramethylammonium hydroxide (25 wt-% solution in H.sub.2O). Afterwards, 692.01 g of colloidal silica (LUDOX AS 40; 40 wt.-% colloidal solution in H.sub.2O) and 11 g of chabazite as seed crystals were added to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 2.5 L. The autoclave was heated within 7 h to 170? C. The temperature was kept constant for 30 h. Afterwards the autoclave was cooled down to room temperature. Then, the solids were separated by filtration and intensive washing with distilled water until the wash-water had a pH of 7. Finally the solid was dried for 10 hours at 120? C. to afford 308 g of product which was then calcined at 550? C. for 5 h under air.

(10) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 117 nm and a crystallinity of 88%. The material displayed a BET surface area of 630 m.sup.2/g. The elemental analysis prior to calcination showed 36 wt-% Si, 2.2 wt-% Al, 11.8 wt-% C, 1.6 wt.-% N and 0.07 wt-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 31.

(11) The particle size distribution of the calcined sample afforded a D10 value of 1.4 ?m, a D50 value of 1.89 ?m, and a D90 value of 2.58 ?m.

(12) The .sup.29Si MAS NMR of the zeolitic material displays peaks at 103.8 and ?110.2 ppm, wherein the integration of the peaks offers relative intensities of 0.397 and 1 for the signals, respectively.

(13) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 58.3 and ?0.7 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.112 for the signals, respectively.

Example 2: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Trimethylcyclohexylammonium and Tetramethylammonium

(14) 534.54 g N,N,N-trimethylcyclohexylammonium hydroxide (20 wt-% solution in H.sub.2O) were mixed with 56.54 g of aluminiumtriisopropylate and 150.62 g tetramethylammonium hydroxide (25 wt-% solution in H.sub.2O). Afterwards, 692.01 g of colloidal silica (LUDOX AS 40; 40 wt.-% colloidal solution in H.sub.2O) and 11 g of chabazite as seed crystals were added to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 2.5 L. The autoclave was heated within 7 h to 170? C. The temperature was kept constant for 30 h. Afterwards the autoclave was cooled down to room temperature. Then, the solids were separated by filtration and intensive washing with distilled water until the wash-water had a pH of 7. Finally the solid was dried for 10 hours at 120? C. to afford 327 g of product which was then calcined at 550? C. for 5 h for affording 296 g of a white powder.

(15) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 117 nm and a crystallinity of 92%. The material displayed a BET surface area of 613 m.sup.2/g, a pore volume of 1.07 cm.sup.3/g and a median pore width of 0.68 nm. The elemental analysis prior to calcination showed 36 wt-% Si, 2.9 wt-% Al, 12.9 wt-% C, 1.6 wt.-% N and 0.13 wt-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 25.

(16) The IR-spectrum of the calcined sample is shown in FIG. 1, wherein amongst others absorption bands having maxima at 3,732 cm.sup.?1 and 1,866 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 1.33.

(17) The particle size distribution of the calcined sample afforded a D10 value of 1.3 ?m, a D50 value of 1.69 ?m, and a D90 value of 2.25 ?m.

(18) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?104.1 and ?110.3 ppm, wherein the integration of the peaks offers relative intensities of 0.334 and 1 for the signals, respectively.

(19) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 58.3 and ?6.3 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.124 for the signals, respectively.

Example 3: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Trimethylcyclohexylammonium and Tetramethylammonium

(20) 276.8 kg N,N,N-trimethylcyclohexylammoniumhydroxide (20 wt-% solution in H.sub.2O) were mixed with 34.80 kg of aluminiumtriisopropylate and 77.99 kg tetramethylammonium hydroxide (25 wt-% solution in H.sub.2O). Afterwards, 358.32 kg of colloidal silica (LUDOX AS 40; 40 wt-% colloidal solution in H.sub.2O) and 5.73 kg CHA seeds were added to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 1600 L. The autoclave was heated within 7 h to 170? C. The temperature was kept constant for 18 h. Afterwards the autoclave was cooled down to room temperature. Then, the solids were separated by filtration and intensively washed until the wash-water had a pH of 7. Finally the solid was dried for 10 hours at 120? C. The material was then calcined at 550? C. for 5 hours.

(21) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 118 nm and a crystallinity of 92%. The material displayed a BET surface area of 654 m.sup.2/g, a pore volume of 1.09 cm.sup.3/g and a median pore width of 0.68 nm. The elemental analysis prior to calcination showed 37 wt-% Si, 2.8 wt-% Al, 12.1 wt-% C, 1.6 wt.-% N and 0.11 wt-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 25.

(22) The IR-spectrum of the calcined sample is shown in FIG. 2, wherein amongst others absorption bands having maxima at 3,733 cm.sup.?1 and 1,866 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 1.35.

(23) The particle size distribution of the calcined sample afforded a D10 value of 0.40 ?m, a D50 value of 0.58 ?m, and a D90 value of 0.89 ?m.

(24) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?104.2 and ?110.5 ppm, wherein the integration of the peaks offers relative intensities of 0.394 and 1 for the signals, respectively.

(25) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 58.5 and ?2.7 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.225 for the signals, respectively.

Comparative Example 1: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Adamantyltrimethylammonium and Tetramethylammonium

(26) 554.6 g 1-adamantyltrimethylammoniumhyroxide (20.44 wt.-% solution in H.sub.2O) were mixed with 101.9 g of aluminiumtriisopropylate and 210.9 g tetramethylammonium hydroxide (25 wt-% solution in H.sub.2O). Afterwards, 1036.2 g of colloidal silica (LUDOX AS 40; 40 wt.-% colloidal solution in H.sub.2O) and 20.7 g of chabazite as seed crystals were added together with 96.4 of distilled H.sub.2O to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 2.5 L. The autoclave was heated within 7 h to 170? C. The temperature was kept constant for 16 h. Afterwards the autoclave was cooled down to room temperature. Then, the solids were separated by filtration and intensive washing with distilled water until the wash-water had a pH of 7. Finally the solid was dried for 10 hours at 120? C. to afford 327 g of a solid product which was then calcined at 600? C. for 5 h to afford 296 g of a white powder.

(27) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 119 nm and a crystallinity of 90%. The material displayed a BET surface area of 644 m.sup.2/g, a pore volume of 0.72 cm.sup.3/g and a median pore width of 0.18 nm. The elemental analysis of the calcined material showed 42 wt-% Si, 3.1 wt-% Al, and 0.15 wt-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 26.

(28) The IR-spectrum of the calcined sample is shown in FIG. 3, wherein amongst others absorption bands having maxima at 3,732 cm.sup.?1 and 1,869 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 1.72.

(29) The particle size distribution of the calcined sample afforded a D10 value of 0.311 ?m, a D50 value of 0.476 ?m, and a D90 value of 0.766 ?m.

(30) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?104.3 and ?110.3 ppm, wherein the integration of the peaks offers relative intensities of 0.311 and 1 for the signals, respectively.

(31) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 58.6 and ?0.8 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.1752 for the signals, respectively.

Comparative Example 2: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Adamantyltrimethylammonium and Tetramethylammonium

(32) 536.6 g 1-adamantyltrimethylammonium hyroxide (21.39 wt.-% solution in H.sub.2O) were mixed with 103.9 g of aluminiumtriisopropylate and 213.6 g tetramethylammonium hydroxide (25 wt.-% solution in H.sub.2O). Afterwards, 1049.1 g of colloidal silica (LUDOX AS 40; 40 wt-% colloidal solution in H.sub.2O) and 21.0 g of chabazite as seed crystals seeds were added together with 97.6 g of distilled H.sub.2O to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 2.5 L. The autoclave was heated within 8 h to 170? C. The temperature was kept constant for 24 h. Afterwards the autoclave was cooled down to room temperature. Then, the solids were separated by filtration and intensive washing with distilled water until the wash-water had a pH of 7. Finally, the solid was dried for 10 hours at 120? C. and then calcined at 600? C. for 5 h thus affording 457 g of a white powder.

(33) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 111 nm and a crystallinity of 92%. The material displayed a BET surface area of 635 m.sup.2/g, a pore volume of 1.13 cm.sup.3/g and a median pore width of 0.49 nm. The elemental analysis of the calcined material showed 41 wt-% Si, 3.1 wt-% Al, and 0.11 wt-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 26.

(34) The IR-spectrum of the calcined sample is shown in FIG. 4, wherein amongst others absorption bands having maxima at 3,733 cm.sup.?1 and 1,871 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 1.59.

(35) The particle size distribution of the calcined sample afforded a D10 value of 0.257 ?m, a D50 value of 0.578 ?m, and a D90 value of 1.1 ?m.

(36) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?104.6 and ?110.6 ppm, wherein the integration of the peaks offers relative intensities of 0.288 and 1 for the signals, respectively.

(37) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 58.7 and ?3.5 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.267 for the signals, respectively.

Comparative Example 3: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Trimethylcyclohexylammonium

(38) 291.3 g trimethylcyclohexylammonium hydroxide (35.0 wt.-% in H.sub.2O) are mixed with 42.88 g Al.sub.2(SO.sub.4).sub.3*18 H.sub.2O and 160.84 ml 1 M aqueous NaOH. Afterwards 482.62 g of colloidal silica (LUDOX AS 40; colloidal SiO.sub.2 40 wt.-% in H.sub.2O) are added to the stirred mixture. Finally 3.83 g of Na-chabazite (having a silica-to-alumina ratio of 30) as seed crystals are dispersed in the reaction mixture. The resulting gel is placed in a sealed autoclave with a total volume of 2.5 L which is then heated to 170? C. for 48 h. After cooling down to room temperature, the obtained sodium containing a zeolite having the CHA framework structure is separated by filtration and is washed with 2000 ml of distilled H.sub.2O three times. Afterwards, the material is dried for 10 h under air at 120? C., resulting in 245.5 g of white powder. The product was then calcined under air with a heating rate of 1 K/min to 550? C. for 5 h.

(39) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 150 nm and a crystallinity of 92%. The material displayed a BET surface area of 627 m.sup.2/g. The elemental analysis of the calcined material showed 37.5 wt.-% Si, 1.6 wt.-% Al, and 0.1 wt.-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 45.

(40) The IR-spectrum of the calcined sample is shown in FIG. 5, wherein amongst others absorption bands having maxima at 3,729 cm.sup.?1 and 1,872 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 1.46.

(41) The particle size distribution of the calcined sample afforded a D10 value of 0.49 ?m, a D50 value of 0.637 ?m, and a D90 value of 0.839 ?m.

(42) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?103.8 and ?110.4 ppm, wherein the integration of the peaks offers relative intensities of 0.266 and 1 for the signals, respectively.

(43) The .sup.27Al MAS NMR of the zeolitic material displays peaks at 57.5 and ?0.0 ppm, wherein the integration of the peaks offers relative intensities of 1 and 0.005 for the signals, respectively.

Comparative Example 4: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Adamantyltrimethylammonium

(44) 174.6 g H.sub.2O were stirred together with 478.8 g of a 20 wt.-% adamantyltrimethylammonium hydroxide solution in H.sub.2O. 102.7 g NaOH (25 wt.-% in H.sub.2O) were added slowly under stirring. After 10 minutes 80.4 g aluminiumtriisopropylate were dissolved in the reaction mixture followed by the addition of 963.4 g of colloidal silica (LUDOX AS 40; colloidal SiO.sub.2 40 wt.-% in H.sub.2O) after 60 minutes. Finally the reaction mixture is stirred for 30 min before it is placed into an autoclave, which is heated to 170? C. for 20 hours. After the autoclave was cooled to room temperature, the resulting dispersion was adjusted by means of a 10 wt.-% HNO.sub.3 solution in H.sub.2O to a pH-value of 7. Afterwards to the resulting solid was filtered and washed with distilled H.sub.2O until a conductivity of below 200 ?S is reached. Afterwards the solid was first dried at 120? C. for 10 h and then calcined under air at 600? C. for 6 h to afford 391 g of a white powder.

(45) The characterization of the material via XRD confirmed the CHA-type framework structure of the product and afforded an average crystal size of 55 nm and a crystallinity of 88%. The material displayed a BET surface area of 615 m.sup.2/g, a pore volume of 1.59 cm.sup.3/g and a median pore width of 0.88 nm. The elemental analysis of the calcined material showed 40.5 wt.-% Si, 3.1 wt.-% Al, and 0.62 wt.-% Na in the sample, thus affording an SiO.sub.2:Al.sub.2O.sub.3 atomic ratio (SAR) of 31.

(46) The IR-spectrum of the calcined sample is shown in FIG. 6, wherein amongst others absorption bands having maxima at 3,733 cm.sup.?1 and 1,870 cm.sup.?1 may be seen, which display a ratio of maximum absorption of the former to the latter of 2.43.

(47) The particle size distribution of the calcined sample afforded a D10 value of 34 nm, a D50 value of 0.28 ?m, and a D90 value of 1.54 ?m.

(48) The .sup.29Si MAS NMR of the zeolitic material displays peaks at ?104.0 and ?110.5 ppm. The .sup.27Al MAS NMR of the zeolitic material displays a peak at 58.1.

Comparative Example 5: Preparation of a Zeolitic Material Having the CHA Framework Structure Using Low Amounts of Trimethylcyclohexylammonium in Combination with Tetramethylammonium

(49) Example 1 of WO 2011/064186 A1 was repeated with the exception that trimethyl-1-adamantylammonium hydroxide was replaced by trimethylcyclohexylammonium. More specifically, 267.0 g N,N,N-trimethylcyclohexylammoniumhydroxide (20 wt-% solution in H.sub.2O) were mixed with 62.03 g of aluminiumtriisopropylate and 154.92 g tetramethylammoniumhydroxide (25 wt-% solution in H.sub.2O). Afterwards, 692.01 g LUDOX AS 40 (40 wt-% colloidal solution in H.sub.2O) were added together with 210 ml H.sub.2O to the stirred mixture. The resulting gel was placed in a stirred autoclave with a total volume of 2.5 L. The autoclave was heated within 7 h to 170? C. The temperature was kept constant for 48 h. Afterwards the autoclave was cooled down to room temperature. Then, the solid was separated by filtration and washed intensively with H.sub.2O until the wash-water had a pH of 7. Finally the solid was dried for 10 hours at 120? C.

(50) The characterization of the resulting product via XRD is displayed in FIG. 7 and revealed an amorphous material. For comparative purposes, the line pattern of the CHA type structure is indicated in the diffractogram of the amorphous material as a reference.

(51) Accordingly, conducting the procedure of WO 2011/064186 A1 using the trimethylcyclohexylammonium template instead of the N,N-trimethylcyclohexylammonium template taught therein as the structure directing agent does not afford a zeolitic material having the CHA-type framework according to the present invention, but rather does not allow for the production of any zeolitic material whatsoever.

Comparative Example 6: Preparation of a Boron-Containing Zeolitic Material Having the CHA Framework Structure Using Low Amounts of Trimethylcyclohexylammonium in Combination with Tetramethylammonium

(52) Example 1 of EP 2325143 A2 was repeated with the exception that trimethyl-1-adamantylammonium hydroxide was replaced by trimethylcyclohexylammonium. More specifically, 577.9 g of N,N,N-cyclohexyltrimethylammonium hydroxide (13.3 wt-% in H.sub.2O), 203.8 tetramethylammoniumhydroxide (25 wt-% solution in H.sub.2O) and 163.4 ml H.sub.2O (DI) were stirred in a beaker for 10 minutes. Afterwards 31 g boric acid (purity 99.6%) were added. The resulting mixture was stirred for another 60 minutes. 999.6 g of an aqueous suspension of colloidal silica (LUDOX AS 40) were given into the reaction mixture followed by another stirring period of 20 minutes before 20 g of B-CHA seed crystals prepared in accordance with Example A of EP 2325143 A2 were dispersed therein as well. Finally the dispersion, was transferred into an autoclave. The crystallization was conducted at 160? C. for 72 h with a stirring rate of 200 rpm.

(53) The obtained solid material was separated from the mother liquor by filtration. Afterwards, the obtained filtercake was dried at 120? C. for 240 minutes under air (heating rate within 30 minutes to 120? C.). From the resulting white powder an X-ray diffractogramm was recorded.

(54) The characterization of the resulting product via XRD is displayed in FIG. 8. An analysis of the pattern using a databank of XRD line patterns revealed that the product consists of a mixture of numerous crystalline compounds, of which not all could be identified and only a portion thereof even potentially displaying a diffraction pattern typical for the CHA-type structure.

(55) Accordingly, also when conducting the procedure of EP 2325143 A2 using the trimethylcyclohexylammonium template instead of the N,N-trimethylcyclohexylammonium template taught therein as the structure directing agent does not a pure zeolitic material having the CHA-type framework according to the present invention, but rather leads to a complex mixture of products of which only a minor portion might display the CHA-type framework structure. In particular, should said mixture contain a zeolitic material having the CHA structure, it would not only be produced in a low yield but would furthermoreif at possible at allrequire an extensive purification procedure for its isolation.

Example 4: SCR Catalyst Testing

(56) For catalyst testing, the samples obtained in the examples and comparative examples were subsequently ion-exchanged with ammonium and copper for obtaining a zeolitic material having the CHA-type framework structure with a copper loading in the range of from 2.2 to 2.9 wt.-% based on the total weight of the exchanged zeolite. The samples were then extruded with polyethylene oxide and H.sub.2O, and the extrudates were calcined for 5 h at 540? C. under air. Afterwards the solids were sieved to a size of 0.5-1 mm. The obtained split fraction was aged for 6 h at 850? C. under air with 10 vol-% H.sub.2O. SCR tests on the extruded powders were performed at 200, 300, and 450? C., respectively, using a gas stream with 500 ppm NO, 500 ppm NH.sub.3, 5% H.sub.2O, 10% O.sub.2, balance N.sub.2, using a gas hourly space velocity GHSV of 80,000 h.sup.?1.

(57) In addition to the catalytic testing performed on the powder (Powder Test), the ion-exchanged samples were additionally coated on monoliths (Core Test) at a washcoat loading of 2.1 g/in.sup.3. The washcoated samples were then aged at 750? C. for 5 h in air with 10% H.sub.2O. The SCR tests on the washcoated samples were performed at 200 and 600? C., respectively, using a gas stream with 500 ppm NO, 500 ppm NH.sub.3, 5% H.sub.2O, 10% O.sub.2 (as air), balance N.sub.2, using a gas hourly space velocity GHSV of 80,000 h.sup.?1. The results from the testing of the powder and washcoat samples are displayed in Table 1.

(58) TABLE-US-00001 TABLE 1 Results from SCR testing. Comp. Comp. Comp. Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Cu [wt-%] 2.3 2.5 2.2 2.7 2.9 2.5 2.3 2.5 2.3 Powder NO.sub.x conversion 71 75 85 n.a. n.a. 77 67 82 75 Test [%] at 200? C. NO.sub.x conversion 80 84 89 n.a. n.a. 82 69 96 84 [%] at 300? C. NO.sub.x conversion 78 80 85 n.a. n.a. 76 69 77 74 [%] at 450? C. Core NO.sub.x conversion n.a. 67 65 73 75 n.a. 71 64 62 Test [%] at 200? C. NO.sub.x conversion n.a. 83 88 76 77 n.a. 78 65 67 [%] at 600? C.

(59) Thus, as may be taken from Table 1, the results obtained using the inventive examples clearly show that the zeolitic material obtained according to the inventive examples of which the synthesis employs a specific combination of a tetraalkylammonium cation and a cycloalkylammonium cation display an improved performance in SCR catalysis, in particular at higher temperatures. This is particularly apparent when comparing the results obtained in the Core Test which were performed on coated monoliths as typically used in the art for the abatement of NO.sub.x emissions such as in the treatment of automotive exhaust gas. Thus, although the inventive catalysts with similar or identical copper loadings display comparable conversion rates at lower temperatures, said conversion increases to a surprising extent upon raising the temperature to clearly surpass the catalysts obtained according to the comparative examples at 600? C. The effect observed for the inventive catalysts is highly unexpected in view of the fact that although a certain improvement in the conversion of NO.sub.x may be observed for Comparative Examples 1 and 2 which are also obtained using a tetraalkylammonium cation however in combination with a structure directing agent well known in the art, said increase in activity is clearly inferior to the surge in activity observed for the inventive catalysts according to Examples 2 and 3. Same applies accordingly when comparing said considerable increase in activity with the results obtained for the materials obtained without a tetraalkylammonium cation in addition to the structure directing agent in Comparative Examples 3 and 4. Consequently, it has been clearly demonstrated by the elaborate comparative testing performed for the present application that the unexpected properties of the inventive materials and in particular their outstanding catalytic performance in SCR is the result of a synergetic effect observed for a highly specific combination of a particular structure directing agent with a tetraalkylammonium cation which may not be achieved by a particular structure directing agent alone, nor by a combination of a different structure directing agent than the one used in the inventive process with a tetraalkylammonium cation.

(60) Accordingly, the zeolitic material having a CHA-type framework provided by the present invention clearly distinguishes itself from zeolitic materials as may for example be obtained according to the art not only in view of their unique physical characteristics but far more due to their highly unexpected chemical properties in particular in the conversion of NO.sub.x by selective catalytic reduction such as to make them particularly promising candidates for highly efficient SCR catalysts. This also applies in view of their highly cost-effective production made possible by the particularly fast synthetic procedure of the present invention employing inexpensive structure directing agents.