PROCESS FOR PREPARING A ZEOLITIC MATERIAL COMPRISING TI AND HAVING FRAMEWORK TYPE CHA

Abstract

A process for preparing a zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O, said process comprising (i) preparing a pre-synthesis mixture comprising water, a CHA framework structure directing agent, and a zeolitic material comprising Ti, having framework type MFI and having a framework structure which comprises Si and O; (ii) removing water from the pre-synthesis mixture obtained from (i) by heating the pre-synthesis mixture to a temperature of less than 100 C. at a pressure of less than 1 bar (abs); (iii) hydrothermally crystallizing the zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O.

Claims

1. A process for preparing a zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O, said process comprising: (i) preparing a pre-synthesis mixture comprising water, a CHA framework structure directing agent, and a zeolitic material comprising Ti, having framework type MFI and having a framework structure which comprises Si and O, wherein a molar ratio of the CHA framework structure directing agent relative to Si, comprised in the zeolitic material having framework type MFI and calculated as SiO.sub.2, said molar ratio being defined as SDA:SiO.sub.2, is at least 0.4:1, and wherein a molar ratio of water relative to Si, comprised in the zeolitic material having framework type MFI and calculated as SiO.sub.2, said molar ratio being defined as H.sub.2O:SiO.sub.2, is at least 30:1; (ii) removing water from the pre-synthesis mixture by heating the pre-synthesis mixture to a temperature of less than 100 C. at a pressure of less than 1 bar(abs) and keeping the temperature of the pre-synthesis mixture in this range and the pressure of the pre-synthesis mixture in this range, obtaining a synthesis mixture comprising water, the CHA framework structure directing agent, and the zeolitic material having framework type MFI, wherein a molar ratio of water relative to Si, comprised in the zeolitic material having framework type MFI and calculated as SiO.sub.2, said molar ratio being defined as H.sub.2O:SiO.sub.2, is at most 25:1; (iii) hydrothermally crystallizing the zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O, comprising heating the synthesis mixture to a temperature in the range of from 140 to 200 C. and keeping the temperature of the synthesis mixture in this range under autogenous pressure, obtaining a mother liquor comprising water and the zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O.

2. The process of claim 1, wherein the CHA framework structure directing agent comprises one or more of a N-alkyl-3-quinuclidinol, a N,N,N-trialkylexoaminonorbornane, a N,N,N-trimethyl-1-adamantylammonium compound, a N,N,N-trimethyl-2-adamantyl-ammonium compound, a N,N,N-trimethylcyclohexylammonium compound, a N,N-dimethyl-3,3-dimethylpiperidinium compound, a N,N-methylethyl-3,3-dimethylpiperidinium compound, a N,N-dimethyl-2-methylpiperidinium compound, 1,3,3,6,6-pentamethyl-6-azonio-bicyclo(3.2.1)octane, N,N-dimethylcyclohexylamine, and a N,N,N-trimethylbenzyl-ammonium compound.

3. The process of claim 1, wherein at least 99 weight %, of the zeolitic material having framework type MFI consist of Si, Ti, O, and H.

4. The process of claim 1, wherein in the pre-synthesis mixture, a molar ratio SDA:SiO.sub.2 is in the range of from 0.4:1 to 2:1, and wherein in the pre-synthesis mixture, a molar ratio H.sub.2O:SiO.sub.2, is in the range of from 30:1 to 50:1.

5. The process of claim 1, wherein the pre-synthesis mixture further comprises a crystalline seed material comprising a zeolitic material comprising Ti, having framework type CHA and having a framework structure which comprises Si and O, and wherein in the pre-synthesis mixture, a molar ratio of Si, comprised in the zeolitic material having framework type CHA comprised in the seed material and calculated as elemental Si, relative to Si, comprised in the zeolitic material having framework type MFI and calculated as SiO.sub.2.

6. The process of claim 1, wherein at least 95 weight % of the pre-synthesis mixture consist of water, the CHA framework structure directing agent, the zeolitic material comprising Ti, having framework type MFI and having a framework structure comprising Si and O.

7. The process of claim 1, wherein in the synthesis mixture, the molar ratio of water relative to relative to Si, comprised in the zeolitic material having framework type MFI and calculated as SiO.sub.2, said molar ratio being defined as H.sub.2O:SiO.sub.2, is in the range of from 5:1 to 25:1.

8. The process of claim 1, wherein the hydrothermally crystallizing according to (iii) comprises heating the synthesis mixture to a temperature in the range of from 145 to 190 C.

9. The process of claim 1, further comprising (iv) cooling the mother liquor; (v) separating the zeolitic material from the mother liquor.

10. A zeolitic material, obtained by the process according to claim 1, comprising Ti, having framework type CHA and having a framework structure which comprises Si and O, wherein from 95 to 100 weight % of the framework structure consist of Si, O, optionally Ti, and optionally H.

11. The zeolitic material of claim 10, wherein from 95 to 100 weight % of the framework structure consist of Si, O, Ti, and optionally H.

12. The zeolitic material of claim 10, wherein at least 75%, of the crystals of the zeolitic material consist of rhombohedra whose longest edge is in the range of from 1 to 20 micrometer, determined according to SEM.

13. The zeolitic material of claim 10, exhibiting an FT-IR spectrum determined having a peak with a minimum at (104010) cm.sup.1.

14. The zeolitic material of claim 10, exhibiting a DTA spectrum determined having a peak with a maximum at (4442) cm.sup.1.

15. An article, comprising: the zeolitic material according to claim 10 wherein the article is a catalytically active material, a catalyst, or a catalyst component.

16. A catalyst, comprising the zeolitic material according to claim 10.

Description

EXAMPLES

Reference Example 1.1: Determination of the XRD Patterns

[0176] The XRD diffraction patterns were determined using a Siemens D5000 powder diffractometer using Cu Kalpha1 radiation (lambda=1.54059 ). Borosilicate glass capillaries (diameter: 0.3 mm) were used as a sample holder. The diffractometer was equipped with a germanium (111) primary monochromator and a Braun linear position-sensitive detector (2Theta coverage=6).

Reference Example 1.2: Scanning Electron Microscopy

[0177] The SEM (Scanning Electron Microscopy) pictures (secondary electron (SE) picture at 15 kV (kiloVolt)) were made using a LEO-1530 Gemini electron microscope at 20 kV to study the morphology of the crystals and the homogeneity of the samples. The samples were gold coated by vacuum vapour deposition prior to analysis.

Reference Example 1.3: (ATR) FTIR Spectrum

[0178] The (ATR) FTIR Spectra were collected using a Nicolet 6700 FT-IR spectrometer. ATR-FTIR spectra between 400 and 4000 cm.sup.1 with a resolution of 4 cm.sup.1 using a Smart Orbit Diamond ATR unit.

Reference Example 1.4: Thermoanalysis DTA and TG

[0179] The thermoanalysis DTA and TG were collected by simultaneous DTA/TG measurements using a Bahr STA-503 thermal analyser. The sample was heated in synthetic air from 30 to 1000 C. with a heating rate of 10 K/min.

Reference Example 2: Titanium Silicalite-1

[0180] A TS-1 zeolitic material was prepared according to WO 2011/064191 A1, page 34, lines 19-39. The TS-1 zeolitic material was obtained wherein the framework structure had the following composition: (1-x) SiO.sub.2.xTiO.sub.2, with x=0.03. The TS-1 exhibited the following physical parameters:

[0181] The (ATR) FTIR spectrum shows signals assigned to the silicate framework at 434.6 cm.sup.1 (very strong), 545.7 cm.sup.1 (strong), 624.6 cm.sup.1 (very weak), 798.8 cm.sup.1 (medium), 958.6 cm.sup.1 (medium), 1068.3 cm.sup.1 (very strong) and 1220.6 cm.sup.1 (very weak). In addition there are two very weak signals at 1627 cm.sup.1 and centered at 3317 cm.sup.1 indicating the presence of a very small amount of water. According to the FTIR spectrum the material is free of organic matter. The .sup.29Si CP MAS NMR spectrum shows two signals at 102.7 ppm (Q3-type) and 112.6 ppm (Q4-type) with approx. relative intensities of 1.5 to 1. The .sup.29Si hpdec MAS NMR spectrum shows only one signal at 113.2 ppm (Q4-type).

Examples 1 to 9: Protocol for the Inventive Examples

Materials Used:

[0182]

TABLE-US-00001 N,N,N-trimethyl-1-adamantylammonium 2.89 mL hydroxide solution (AdaTMAOH) (1.04 molar): Titanium silicalite-1 (TS-1) according to 0.30 g Reference Example 2 (optional) NaOH solution (1 molar) 0.1 mL (optional) KOH solution (1 molar) 0.1 mL (optional) Ti-CHA seeds

[0183] 2.89 mL of an aqueous AdaTMAOH solution (1.04 molar), 0.30 g TS-1, optionally 0.1 mL aqueous NaOH solution (1 molar) or optionally 0.1 mL aqueous KOH solution (1 molar), and optionally Ti-CHA seeds (1 weight-% of the total silicon content), were mixed in a Teflon beaker (volume of 45 mL) and stirred at room temperature for 10 min. The thus obtained pre-synthesis mixture had the following molar composition:

0.97 SiO.sub.2:0.03 TiO.sub.2:(optionally) 0.022 NaOH or KOH:0.66 AdaTMAOH:35 H.sub.2O

[0184] The pre-synthesis mixture was then heated in a vacuum oven at a temperature T.sub.1 and an absolute pressure of 50 mbar under static conditions for X.sub.1 hours, and the loss of water was recorded. The thus obtained synthesis mixture had the molar composition:

0.97 SiO.sub.2:0.03 TiO.sub.2:(optionally) 0.022 NaOH or KOH:0.66 AdaTMAOH:Y.sub.1H.sub.2O

[0185] The hydrothermal crystallization step was then carried out as follows. The Teflon beaker containing the synthesis mixture was put into a steel autoclave, the autoclave was sealed, and then the autoclave was heated to 160 C. under static conditions for a number of days (d).

[0186] After pressure release and cooling to room temperature, the product (Ti-CHA which comprises Si and O in the framework) was thoroughly washed with distilled water, until the washing water had a conductivity of less than 200 microSiemens. The thus obtained washed product (Ti-CHA which comprises Si and O in the framework) was then separated by centrifugation and dried in air at room temperature overnight.

[0187] Based on the above protocol, a set of inventive examples 1 to 9 was carried out using the amounts and conditions as summarized in the following Table 1:

TABLE-US-00002 TABLE 1 Summary of the Inventive Examples Inventive Examples 1 2 3 4 5 6 7 8 9 SDA/mol 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 NaOH/mol 0.022 0.022 0.022 0.066 0.011 0.022 0.022 0.022 KOH Al(OH).sub.3/mol (Ti-CHA) seeds + + + + + + + Ti/ C./X.sub.1/h 50/3 50/3 50/3 50/3 50/3 50/3 50/3 60/1.5 70/2 Loss of H.sub.2O/g n.d. 1.7 1.85 n.d. 1.25 1.90 n.d. 1.62 2.01 Crystallization 7 7 7 7 7 7 14 7 7 time/d Pre-synthesis 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 mixture, molar ratio H.sub.2O:SiO.sub.2 synthesis 20:0.97 16:0.97 14:0.97 20:0.97 21:0.97 13.5:0.97 20:0.97 17:0.97 12:0.97 mixture, molar ratio H.sub.2O:SiO.sub.2

Notes for Table 1:

[0188] for Example 3, instead of NaOH, KOH was used. [0189] for Examples 4 and 5 to obtain 0.066 mol and 0.011 mol of NaOH respectively, rather than 0.1 mL of NaOH solution (1 molar), 0.3 mL and 0.05 mL was employed respectively. [0190] indicates that the respective component was not employed. [0191] + indicates that Ti-CHA seeds were employed. [0192] n.d. indicates not determined [0193] For each of the inventive examples a Ti-CHA product was obtained as confirmed by XRD in accordance with reference example 1.1.

[0194] As can readily be seen from Table 1, the product Ti-CHA which comprises Si and O was obtained with each of examples 1 to 9. Notably, Examples 1 and 2 for instance highlight that a Ti-CHA seed although not essential, may optionally be employed. Example 6 demonstrates that a source of an alkali metal is not essential, although varying amounts of an alkali metal may optionally be employed as demonstrated by examples 3 to 5. Furthermore, example 7 highlights that optionally longer hydrothermal crystallization times may be employed. Finally, examples 8 and 9 demonstrate some further conditions for removing water from the pre-synthesis mixture. Analytical data for Ti-CHA obtained according to the invention are provided in FIGS. 1 to 4.

Comparative Examples 1 to 5: Protocol for the Comparative Examples

[0195] For comparative examples 1 to 5, a similar protocol was employed based on that used for the inventive examples, with the following modifications as summarized in Table 2:

TABLE-US-00003 TABLE 2 Summary of the Comparative Examples Comparative Examples 1 2 3 4 5 SDA/mol 0.66 0.66 0.36 0.36 0.66 NaOH/mol 0.022 0.22 0.017 0.017 0.022 Al(OH).sub.3/mol 0.9 (Ti-CHA) seeds + T.sub.1/ C./X.sub.1/h none none boiled 50/3 50/3 Loss of H.sub.2O/g none none n.d. n.d. n.d. Crystallization 7 7 7 6 7 time (d) Product amorphous mainly mixture of mixture of mainly obtained material amorphous TS-1 and TS-1 and amorphous material amorphous amorphous material material material Pre-synthesis 35:0.97 35:0.97 35:0.97 35:0.97 35:0.97 mixture, molar ratio H.sub.2O:SiO.sub.2 Synthesis 35:0.97 35:0.97 30:0.97 20:0.97 20:0.97 reaction mixture, molar ratio H.sub.2O:SiO.sub.2

Notes for Table 2:

[0196] for comparative examples 1 and 12 none indicates the protocol did not include heating in a vacuum oven at T.sub.1 and ca. 50 mbar; hence there was no removal of water from the pre-synthesis mixture. [0197] for comparative example 2, 1 mL of NaOH (1 molar) was employed when preparing the pre-synthesis mixture. [0198] for comparative examples 3 and 4 0.075 mL of NaOH solution (1 molar) and 1.5 mL of (AdaTMAOH) (1.04 molar) was employed to obtain 0.017 and 0.36 mol respectively when preparing the pre-synthesis mixture. [0199] indicates that the respective component was not employed. [0200] + indicates that that Ti-CHA seeds were employed. [0201] n.d. indicates not determined. [0202] The product obtained was determined by XRD according to reference example 1.1. [0203] for comparative example 5, 0.3 g Al(OH).sub.3 were added when preparing the pre-synthesis mixture.

[0204] As can readily be seen from Table 2, Comparative Examples 1 to 3, if the step of removing water from the pre-synthesis mixture is omitted, mixtures comprising significant amounts of amorphous material rather than Ti-CHA are obtained. Furthermore, Comparative Example 4 highlights that if a molar ratio of AdaTMAOH (SDA):SiO.sub.2 of at least 0.4:1 is not employed, a mixture comprising mainly amorphous material is obtained. Finally, Comparative Example 5 highlights that when aluminium is comprised in the pre-synthesis mixture, this has a detrimental effect, whereby a mixture comprising mainly amorphous material was obtained.

BRIEF DESCRIPTION OF THE FIGURES

[0205] FIG. 1: shows the XRD pattern of Ti-CHA according to the invention.

[0206] FIG. 2: shows the SEM picture of Ti-CHA according to the invention. As can be seen, Ti-CHA crystallizes as small rhombohedra having edges with a length of about 3-15 micrometer.

[0207] FIG. 3: shows the (ATR) FTIR Spectrum of Ti-CHA according to the invention. The x-axis shows the wave number/cm.sup.1

[0208] FIG. 4: shows the thermoanalysis DTA and TG of Ti-CHA according to the invention.

CITED PRIOR ART

[0209] WO 2011/06419 A1