Process for the production of a zeolitic material via solvent-free interzeolitic conversion

Abstract

A process for preparing a zeolitic material containing YO.sub.2 and X.sub.2O.sub.3, where Y and X represent a tetravalent element and a trivalent element, respectively, is described. The process includes (1) a step of preparing a mixture containing one or more structure directing agents, seed crystals, and a first zeolitic material containing YO.sub.2 and X.sub.2O.sub.3 and having FAU-, GIS-, MOR-, and/or LTA-type framework structures; and (2) a step of heating the mixture for obtaining a second zeolitic material containing YO.sub.2 and X.sub.2O.sub.3 and having a different framework structure than the first zeolitic material. The mixture prepared in (1) and heated in (2) contains 1000 wt % or less of H.sub.2O based on 100 wt % of YO.sub.2 in the framework structure of the first zeolitic material. A zeolitic material obtainable and/or obtained by the process and its use are also described.

Claims

1. A process for preparing a zeolitic material comprising YO.sub.2 and X.sub.2O.sub.3 in its frame-work structure, wherein Y stands for a tetravalent element and X stands for a trivalent element, said process comprising: (1) preparing a mixture comprising one or more structure directing agents, seed crystals, and a first zeolitic material comprising YO.sub.2 and X.sub.2O.sub.3 in its framework structure, wherein the first zeolitic material has at least one framework structure selected from the group consisting of FAU-, GIS-, MOR-, and LTA-type framework structures; and (2) heating the mixture obtained in (1) for obtaining a second zeolitic material comprising YO.sub.2 and X.sub.2O.sub.3 in its framework structure, wherein the second zeolitic material obtained in (2) has a different type of framework structure than the first zeolitic material; wherein the mixture prepared in (1) and heated in (2) contains 1 to 170 wt. % H.sub.2O based on 100 wt.-% of YO.sub.2 in the framework structure of the first zeolitic material.

2. The process of claim 1, wherein the second zeolitic material obtained in (2) has a CHA-type framework structure.

3. The process of claim 1, wherein the one or more structure directing agents comprises one or more tetraalkylammonium cation R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+-containing compounds, wherein R.sup.1, R.sup.2, and R.sup.3 independently from one another stand for alkyl, and wherein R.sup.4 stands for cycloalkyl.

4. The process of claim 1, wherein the one or more structure directing agents comprises one or more tetraalkylammonium cation R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+-containing compounds, wherein R.sup.1, R.sup.2, and R.sup.3 independently from one another stand for alkyl, and wherein R.sup.4 stands for adamantyl and/or benzyl.

5. The process of claim 1, wherein the one or more structure directing agents comprises one or more tetraalkylammonium cation R.sup.1R.sup.2R.sup.3R.sup.4N.sup.+-containing compounds, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently from one another stand for alkyl, and wherein R.sup.3 and R.sup.4 form a common alkyl chain.

6. The process of claim 1, wherein Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and a mixture thereof.

7. The process of claim 1, wherein X is selected from the group consisting of Al, B, In, Ga, and a mixture thereof.

8. The process of claim 1, wherein the heating (2) is conducted at a temperature ranging from 170 to 300 C.

9. The process of claim 8, wherein the heating (2) is conducted for a period in the range of from 0.1 h to 6 h.

10. The process of claim 1, further comprising (3) calcining the second zeolitic material obtained in (2).

11. The process of claim 10, further comprising (4) subjecting the zeolitic material obtained in (2) or (3) to an ion-exchange procedure.

12. The process of claim 11, further comprising (5) calcining the zeolitic material obtained in (4).

13. The process of claim 1, wherein the seed crystals comprise a zeolitic material having a CHA-type and/or an AEI-type framework structure.

14. A zeolitic material, obtained according to the process of claim 1.

15. A molecular sieve, an adsorbent, a catalyst, and/or a catalyst support, comprising the zeolitic material of claim 14.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the XRD patterns of the samples according to Example 1, designated as a, and according to Example 2, designated as b. In the figure, the angle 2 theta in 0 is shown along the abscissa and the intensities are separately plotted along the ordinate for each diffractogram.

(2) FIG. 2 shows the Ar sorption isotherms of the sample according to Example 1, designated as a, and according to Example 2, designated as b. In the figure, the relative pressure P/P.sub.0 is plotted along the abscissa and the volume of argon (under standard temperature and pressure) adsorbed in cm.sup.3/g.

(3) FIG. 3 shows the .sup.27Al MAS NMR spectrum of the as-synthesized zeolitic material obtained from Example 1. In the figure, the chemical shift in ppm is plotted along the abscissa and the relative intensity is plotted along the ordinate.

(4) FIG. 4 shows the .sup.29Si MAS NMR spectrum of the as-synthesized zeolitic material from Example 1. In the figure, the chemical shift in ppm is plotted along the abscissa and the relative intensity is plotted along the ordinate.

(5) FIG. 5 shows the X-ray diffraction pattern of the zeolitic material obtained from Example 4. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are separately plotted along the ordinate for each diffractogram.

(6) FIG. 6 displays the Ar sorption isotherm of the zeolitic material obtained from Example 4. In the figure, the relative pressure P/P.sub.0 is plotted along the abscissa and the volume of argon (under standard temperature and pressure) adsorbed in cm.sup.3/g.

(7) FIG. 7 displays the XRD of the as synthesized zeolitic material obtained according to Comparative Example 1 prior to ion exchange with copper. In the diffractogram, the line pattern of Chabazite is shown for comparative purposes. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are separately plotted along the ordinate for each diffractogram.

(8) FIG. 8 displays the results from NH.sub.3SCR catalyst testing performed in Example 5 over the copper ion-exchanged zeolite of Example 1 designated with .square-solid. and Example 2 designated as .circle-solid.. In the figure, the temperature measured at the catalyst in C. is shown along the abscissa and the NO conversion rate in % is plotted along the ordinate.

(9) FIG. 9 shows the XRD pattern of the as-synthesized zeolitic material obtained according to Example 3. In the figure, the angle 2 theta in is shown along the abscissa and the intensities are separately plotted along the ordinate for each diffractogram.

EXPERIMENTAL SECTION

(10) The chemicals used in this work include ammonium nitrate (NH.sub.4NO.sub.3, AR, 99%, Beijing Chemical Reagent Co., Ltd.), N,N-dimethylcyclohexylamine (AR, 98%, Aladdin Chemistry Co., Ltd.), bromoethane (AR, 98%, Aladdin Chemistry Co., Ltd.), acetone (AR, 99.5%, Aladdin Chemistry Co., Ltd.), ethanol (AR, 99.7%, Shanghai Lingfeng Chemical Reagent Co, Ltd.), and N,N,N-trimethyl-1-1-adamantammonium hydroxide (TMAdaOH, 25%, Sichuan Zhongbang Co., Ltd.). FAU (Si/Al=11.6, H-FAU) and SSZ-13 (benchmark) were supplied by BASF SE. They were used directly without further processing unless otherwise stated.

(11) The N,N-dimethyl-Aethyl-cyclohexylammonium bromide (DMCHABr) template compound employed in the examples was prepared as follows: 45 g of ethylbromide was added to a mixture of 50 g of N,N-dimethylcyclohexylamine and 100 g of ethanol. After reaction for overnight at 50 C., the product was finally obtained by washing with acetone and drying under vacuum condition.

(12) The N,N-dimethyl-2,6-dimethylpiperridinium hydroxide template compound employed in the examples was prepared as follows: 30 g of 2,6-dimethylpiperidine was mixed with 150 ml of ethanol and 38 g of potassium carbonate. Then, 120 g of methyl iodide was added dropwise, keeping the reaction mixture under stirring for 3 days at room temperature. After reaction, the mixture was concentrated under vacuum and precipitated by addition of diethyl ether. The resultant solid was further extracted and washed with CHCl.sub.3 to remove completely possible inorganic salts. The iodide salt was converted to the hydroxide salt by treatment with a hydroxide anion exchange resin. The hydroxide ion concentration is determined by titration of the resulting solution using phenolphthale as the indicator.

(13) X-ray powder diffraction (XRD) patterns were measured with a Rigaku Ultimate VI X-ray diffractometer (40 kV, 40 mA) using CuK (=1.5406 ) radiation. The argon sorption isotherms at the temperature of liquid nitrogen were measured using Micromeritics ASAP 2020M and Tristar system. The sample composition was determined by inductively coupled plasma (ICP) with a Perkin-Elmer 3300DV emission spectrometer. Scanning electron microscopy (SEM) experiments were performed on Hitachi SU-1510 electron microscopes. .sup.27Al and .sup.29Si solid MAS NMR spectra were recorded on a Varian Infinity Plus 400 spectrometer.

Example 1: Preparation of a Zeolitic Material Having a CHA-Type Framework Structure (SSZ-13) at 150 C. Via Interzeolitic Transformation of Zeolite Y

(14) 2.4 g of zeolite Y (Si/Al=10.8) containing H.sub.2O (1.5 g of Y and 0.9 g H.sub.2O), 0.75 g of DMECHABr, 0.12 g of NaOH and 0.028 g of uncalcined SSZ-13 zeolite seeds (2 wt.-%) were mixed together for affording a reaction mixture which contained 65 wt.-% of H.sub.2O based on 100 wt.-% of SiO.sub.2 contained in the zeolite Y of the mixture. After grinding for 5-7 min, the powder mixture was transferred to an autoclave and sealed. After heating at 150 C. for 72 h, the sample was completely crystallized. The obtained sample was calcined at 550 C. for 5 hours to remove the template. The H-form of the sample was prepared by triple ion-exchange with 1 M NH.sub.4NO.sub.3 solution at 80 C. for 1 h and calcination at 550 C. for 5 h.

(15) The reaction yield was 94%, and the resulting SSZ-13 displayed an Si to Al molar ratio of 10.4 as determined by ICP.

(16) FIG. 1 shows XRD pattern of the as-synthesized zeolitic material (cf. diffractogram a), which exhibits well resolved peaks associated with the CHA-type zeolite structure. FIG. 2 shows the argon sorption isotherm of the calcined sample (cf. adsorption isotherm a), showing a typical Langmuir-type curve at a relative pressure of 10<P/P.sub.0<0.01, which is due to the filling of micropores in the sample. At a relative pressure of 0.5-0.95, a hysteresis loop can be observed, suggesting the presence of mesoporosity and macroporosity. BET surface area and pore volume of the sample are 667 m.sup.2/g and 0.31 cm.sup.3/g, respectively.

(17) FIG. 3 shows the .sup.27Al MAS NMR spectrum of the as-synthesized zeolitic material, giving a sharp band at 56 ppm associated with tetrahedrally coordinated aluminum species in the framework. The absence of a signal around zero ppm indicates that there is no extra-framework Al.sup.3+ species in the sample.

(18) FIG. 4 shows the 29Si MAS NMR spectrum of the as-synthesized zeolitic material, exhibiting peaks at about 110.7 and 104.9 ppm associated with Si(4Si) and Si(3Si), respectively.

Example 2: Preparation of a Zeolitic Material Having a CHA-Type Framework Structure (SSZ-13) at 180 C. Via Inzterzeolitic Transformation of Zeolite Y

(19) Example 1 was repeated, wherein the powder mixture was not heated at 150 C. but rather heated at 180 C. for 24 h

(20) FIG. 1 shows the XRD pattern of the as-synthesized zeolitic material (cf. diffractogram b), which exhibits well resolved peaks associated with CHA-type zeolite structure. FIG. 2 shows the argon sorption isotherms of these calcined sample (cf. adsorption isotherm b). At a relative pressure of 0.5-0.95, a hysteresis loop can be observed, suggesting the presence of mesoporosity and macroporosity in these samples. BET surface area and pore volume of the sample are 552 m.sup.2/g and 0.26 cm.sup.3/g, respectively.

Example 3: Preparation of a Zeolitic Material Having a CHA-Type Framework Structure (SSZ-13) at 240 C. Via Inzterzeolitic Transformation of Zeolite Y

(21) 1 g of zeolite Y (Si/Al=10.8) containing H.sub.2O (0.625 g of Y and 0.375 g H.sub.2O), 0.9 g of template (50 wt.-% aqueous solution of N,N,N-1-trimethyladamantammonium hydroxide), 0.08 g of NaOH and 0.037 g of uncalcined SSZ-13 zeolite seeds were mixed together for affording a reaction mixture which contained 142 wt.-% of H.sub.2O based on 100 wt.-% of SiO.sub.2 contained in the zeolite Y of the mixture. After grinding for 5-7 min, the powder mixture was transferred to an autoclave and sealed. After heating at 240 C. for 1 hour, the sample was completely crystallized. The obtained sample was calcined at 550 C. for 5 hours to remove the template. The H-form of the sample was prepared by triple ion-exchange with 1 M NH.sub.4NO.sub.3 solution at 80 C. for 1 h and calcination at 550 C. for 5 h.

(22) The reaction yield was 80%, and the resulting SSZ-13 displayed an Si to Al molar ratio of 8.6 as determined by ICP.

(23) FIG. 9 shows the XRD pattern of the as-synthesized zeolitic material, which exhibits well resolved peaks associated with the CHA-type zeolite structure.

Example 4: Preparation of a Zeolitic Material Having a AEI-Type Framework Structure (SSZ-39) Via Inzterzeolitic Transformation of Zeolite Y

(24) 1 g of zeolite Y (Si/Al=10.8) containing H.sub.2O (0.625 g of Y and 0.375 g H.sub.2O), 0.7 g of template (40 wt.-% aqueous solution of N,N-dimethyl-2,6-dimethylpiperridinium hydroxide), 0.35 g of NaOH and 0.02 g of uncalcined SSZ-39 zeolite seeds were mixed together for affording a reaction mixture which contained 137 wt.-% of H.sub.2O based on 100 wt.-% of SiO.sub.2 contained in the zeolite Y of the mixture. After grinding for 5-7 min, the powder mixture was transferred to an autoclave and sealed. After heating at 140 C. for 72 hours, the sample was completely crystallized. The obtained sample was calcined at 550 C. for 5 hours to remove the template. The H-form of the sample was prepared by triple ion-exchange with 1 M NH.sub.4NO.sub.3 solution at 80 C. for 1 h and calcination at 550 C. for 5 h.

(25) The reaction yield was 32%, and the resulting SSZ-13 displayed an Si to Al molar ratio of 5.0 as determined by ICP.

(26) FIG. 5 shows the X-ray diffraction pattern of the zeolitic material obtained, which displays an AEI-type framework structure.

(27) FIG. 6 displays the argon sorption isotherm of the zeolitic material obtained, according to which the sample has a BET surface area of 596 m.sup.2/g and a pore volume of 0.27 cm.sup.3/g, respectively.

Comparative Example 1: Preparation of a Zeolitic Material Having a CHA-Type Framework Structure Via Hydrothermal Synthesis

(28) 277 kg of a 20 wt.-% aqueous solution of cyclohexyltrimethylammonium hydroxide (CHTMAOH) and 78 kg of a 25 wt.-% aqueous solution of tetramethylammonium hydroxide (TMAOH) were placed in an autoclave after which 34.8 kg of aluminumtriisopropylate were added under stirring at 50 rpm, and further stirred at that rate until the aluminumtriisopropylate had entirely dissolved. 358 kg of a 40 wt.-% solution of colloidal silica (Ludox AS40) were then added, and the mixture stirred an additional 10 min. Finally, 5.7 kg of SSZ-13 zeolite were added to the mixture under stirring, wherein the pH of the resulting mixture was measured to be 14.24. The mixture was then crystallized at 170 C. for 18 h, wherein the mixture was first progressively heated to the reaction temperature using a constant temperature ramp over a period of 7 hours. A white suspension having a pH of 13.14 was obtained, which was filtered and the solid washed with distilled water until substantial electroneutrality of the washwater was achieved. The resulting solid was dried and subsequently calcined at 550 C. for 5 h under air for obtaining a powder having a crystallinity of 92% as determined by XRD and displaying an average crystal size of 107 nm.

(29) As may be taken from XRD of the resulting material displayed in FIG. 7, the resulting zeolitic material has the CHA framework structure.

(30) Elemental analysis of the product afforded:

(31) Si: 34.0 wt.-%

(32) Al: 2.6 wt.-%

(33) Na: 0.12 wt.-%

(34) C: 12.6 wt.-%

(35) N: 1.7 wt.-%

(36) 1.3 kg of distilled water and 202.2 g of the calcined zeolitic material were placed in a 4 liter receptacle and heated to 60 C. and held at that temperature for 30 min. Subsequently, 20.13 g of copper(II) acetate and 2.22 g of 70% acetic acid were added and the mixture further heated at 60 C. for 1 h under constant stirring of the mixture at 200 rpm. Heating was then discontinued, and 975 g of distilled water were added to the mixture which was then filtered and washed with distilled water until the washwater displayed a conductivity of 138 S. The filter cake was then dried over night at 120 C. affording 208 g of copper ion exchanged zeolitic material.

(37) Elemental analysis of the copper ion-exchanged product afforded:

(38) Si: 39.0 wt.-%

(39) Al: 3.1 wt.-%

(40) Cu: 2.2 wt.-%

(41) Na: 0.02 wt.-%

(42) C: 0.11 wt.-%

Example 5: Catalytic Testing Performed on Fresh Catalysts

(43) The selective catalytic reduction activity measurements were carried out in a fixed-bed quartz reactor with the reactant gas mixture containing 500 ppm NO.sub.x 500 ppm NH.sub.3, 10% O.sub.2, and N.sub.2 balance. The gas hourly space velocity (GHSV) was 80,000 h.sup.1. Copper ion-exchanged samples from Examples 1 and 2 and from Comparative Example 1 (benchmark) were prepared via ion-exchanged method with Cu(NO.sub.3).sub.2 aqueous solution, and the copper loading of the samples was about 2 wt %.

(44) After ion-exchanged with Cu(NO.sub.3).sub.2 aqueous solution, the copper ion-exchanged samples from Examples 1 and 2 were tested in the selective catalytic reduction of NO.sub.x with NH.sub.3 (NH.sub.3SCR), the results of which are shown in FIG. 8. Both samples show nearly 100% of NO conversion in the temperature range of 200-450 C. Surprisingly, however, the zeolitic material obtained according to Example 2 displays a considerably improved performance at higher temperatures, starting at 350 C., wherein the discrepancy continually increases with increasing temperature.

Example 6: Catalytic Testing Performed on Aged Catalysts

(45) Copper ion-exchanged samples from Example 1 and Comparative Example 1 as obtained according to Example 4 were subject to separate aging procedures. In a first aging procedure, respective samples were subject to aging at 650 C. in air with a water content of 10 vol. % for 50 h (HDD aging), whereas in a further aging procedures, separate samples were respectively subject to aging at 800 C. in air with a water content of 10 vol. % for 16 h (LDD aging). The aged samples were then respectively tested with respect to their NO.sub.x conversion efficiency according to the testing procedure as described in Example 4, wherein the results of said testing are displayed in Table 1.

(46) TABLE-US-00001 TABLE 1 NO.sub.x conversion rates measured for samples according to Example 1 and Comparative Example 1 depending on aging conditions and reaction temperature. NO.sub.x conversion (%) NO.sub.x conversion (%) Sample (aging conditions) at 200 C. at 575 C. Example 1 (650 C./50 h) 64.2 98.1 Comp. Ex. 1 (650 C./50 h) 78.1 92.8 Example 1 (800 C./16 h) 69.2 96.4 Comp. Ex. 1 (800 C./16 h) 70.5 86.0

(47) Thus, as may be taken from the results displayed in table 1, the performance of the inventive example subject to mild aging at 650 C. displays an inferior rate of NO.sub.x conversion at low temperatures yet clearly outperforms the catalyst according to comparative example 1 at 575 C., wherein NO.sub.x conversion achieved by the inventive catalyst is almost complete by attaining a value of 98.1%. Interestingly, however, after having been subject to severe aging at 800 C., the inventive catalyst displays an NO.sub.x conversion rate which matches the conversion rate achieved by the sample according to comparative example 1, whereas at high temperatures, the inventive catalyst outperforms the catalyst according to the comparative example to an even greater degree than after having been subject to mild their aging conditions.

(48) Accordingly, it has surprisingly been found that the inventive zeolitic materials obtained according to the inventive process not only display a highly improved performance in NO.sub.x conversion at elevated temperatures compared to known catalyst, but furthermore are able to match the conversion rates of the known catalysts at lower temperatures after having been subject to more severe aging conditions. Therefore, the inventive catalysts display a clearly improved performance in NO.sub.x conversion activity compared to catalysts obtained according to the art at high temperatures, wherein even further improvement is observed relative to conventional catalysts upon increasing levels of aging.

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