A LAYERED SILICATE

Abstract

Provided is a crystalline layered silicate, having an X-ray diffraction pattern comprising reflections at 2-theta values of (5.3±0.2)°, (8.6±0.2)°, (9.8±0.2)°, (21.7±0.2)° and (22.7±0.2). Also provided are a process for preparing the crystalline layered silicate and uses of the layered silicate. The process comprises steps of: (i) preparing a synthesis mixture comprising water, a source of Si, and a structure directing agent comprising a diethyldimethylammonium compound; (ii) subjecting the synthesis mixture obtained from (i) to hydrothermal synthesis conditions comprising heating the synthesis mixture obtained from (i) to a temperature in the range of from 110 to 180° C. and keeping the synthesis mixture at a temperature in this range under autogenous pressure for 1 to 6 days, obtaining a mother liquor comprising the crystalline layered silicate.

Claims

1. A crystalline layered silicate, having an X-ray diffraction pattern, when measured at a temperature in a range of from 15 to 25° C. with CuKalpha.sub.1,2 radiation having a wavelength of 0.15419 nm, comprising reflections at 2-theta values of: 5.3±0.2°; 8.6±0.2°; 9.8±0.2°; 21.7±0.2°, and 22.7±0.2°.

2. The silicate of claim 1, having: an IR spectrum comprising twelve peaks with maxima at 475±5 cm.sup.−1, 526±5 cm.sup.−1, 587±5 cm.sup.−1, 609±5 cm.sup.−1, 628±5 cm.sup.−1, 698±5 cm.sup.−1, 724±5 cm.sup.−1, 776±5 cm.sup.−1, 587±5 cm.sup.−1, 794±5 cm.sup.−1, 809±5 cm.sup.−1, and 837±5 cm.sup.−1.

3. The silicate of claim 1, wherein from 95 to 100 wt. % of the layered silicate consists of Si, O, C, N, and H.

4. The silicate of claim 1, having a unit cell of formula (I):
(C.sub.6H.sub.16N).sub.8[Si.sub.32O.sub.64(OH).sub.8]*xH.sub.2O  (I), wherein x is in a range of from 8 to 30.

5. A process for preparing a crystalline layered silicate the process comprising: (i) preparing a synthesis mixture comprising water, a source of Si, and a structure directing agent comprising a diethyldimethylammonium compound; (ii) subjecting the synthesis mixture, comprising water, a source of Si, and a structure directing agent comprising a diethyldimethylammonium compound, to hydrothermal synthesis conditions comprising heating the synthesis mixture to a temperature in a range of from 110 to 180° C. and keeping the synthesis mixture at a temperature in this range under autogenous pressure for 1 to 6 days, to obtain a mother liquor comprising the crystalline layered silicate.

6. The process of claim 5, wherein the source of the Si comprises a wet-process silica, a dry-process silica, and/or a colloidal silica.

7. The process of claim 5, wherein, in the synthesis mixture, a molar ratio of the structure directing agent relative to the source of Si, calculated as SiO.sub.2, defined as SDA:SiO.sub.2, is in a range of from 0.3:1 to 2:1.

8. The process of claim 5, wherein from 95 to 100 wt. % of the synthesis mixture consists of water, the source of Si, and the structure directing agent comprising a diethyldimethylammonium compound.

9. The process of claim 5, wherein the synthesis mixture is prepared by a process comprising (i.1) preparing a mixture comprising water, the source of Si, and the structure directing agent comprising a diethyldimethylammonium compound at a temperature of the mixture in a range of from 10 to 40° C.; (i.2) heating the mixture to a temperature in a range of from 50 to 120° C. and keeping the mixture at a temperature in this range, to obtain the synthesis mixture.

10. The process of claim 9, wherein the heating (i.2) comprises heating the mixture to a temperature in a range of from 50 to 100° C.

11. The process of claim 9, wherein in the synthesis mixture, a molar ratio of water relative to the source of Si, calculated as SiO.sub.2, defined as the H.sub.2O:SiO.sub.2, is in a range of from 4:1 to 15:1.

12. The process of claim 5, wherein, in the subjecting (ii), the synthesis mixture is heated to a temperature in a range of from 120 to 170° C.

13. The process of claim 5, further comprising (iii) optionally cooling the mother liquor obtained from the subjecting (ii); (iv) separating the crystalline layered silicate from the mother liquor.

14. A layered silicate, obtained by the process of claim 5.

15. A catalytically active material, catalyst, intermediate suitable for preparing a catalyst, or catalyst component, comprising the silicate of claim 1.

16. The silicate of claim 1, having a .sup.29Si MAS NMR spectrum comprising Q.sup.3-type signals at −99±2 ppm and −101±2 ppm and Q.sup.4-type signals at −106±2 ppm and −108±2 ppm.

17. The silicate of claim 2, having a .sup.29Si MAS NMR spectrum comprising Q.sup.3-type signals at −99±2 ppm and −101±2 ppm and Q.sup.4-type signals at −106±2 ppm and −108±2 ppm.

18. The silicate of claim 2, having an IR spectrum further comprising peaks with maxima at 1397±5 cm.sup.−1, 1421±5 cm.sup.−1, 1457±5 cm.sup.−1, 1464±5 cm.sup.−1, and 1487±5 cm.sup.−1.

19. The silicate of claim 1, wherein from 98 to 100 wt. % of the layered silicate consists of Si, O, C, N, and H.

20. The silicate of claim 1, wherein from 99 to 100 wt. % of the layered silicate consists of Si, O, C, N, and H.

Description

EXAMPLES

Reference Example 1.1: Determination of the XRD Patterns

[0133] The XRD diffraction patterns were determined using a Siemens D5000 powder diffractometer using Cu Kalpha1 radiation (lambda=1.54059 Angstrom). 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°). For Example 1, the structure was solved by comparison with the XRD powder data of ITQ-8 and by comparison with the FTIR spectrum of ITQ-8. The structure of RUB-56 was refined using the FullProf 2K program.

Reference Example 1.2: Scanning Electron Microscopy

[0134] The SEM (Scanning Electron Microscopy) pictures (secondary electron (SE) picture at 20 kV (kiloVolt)) were made using a LEO-1530 Gemini electron microscope The samples were gold coated by vacuum vapour deposition prior to analysis. SEM was used to study the morphology of the crystals and the homogeneity of the samples.

Reference Example 1.3: (ATR) IR Spectrum

[0135] The (ATR) IR spectra were collected using a Nicolet 6700 FT-IR spectrometer. ATR-FTIR spectra were taken between 400 and 4000 cm.sup.−1 with a resolution of 4 cm.sup.−1 from a sample using a Smart Orbit Diamond ATR unit.

Reference Example 1.4: .SUP.29.Si MAS NMR spectrum

[0136] The .sup.23Si MAS NMR spectra were recorded at around 23° C. with a Bruker ASX-400 spectrometer using standard Bruker MAS probes and operated at 79.493 MHz. In order to average the chemical shift anisotropies, samples were spun about the magic angle. Tetramethylsilane was used as a chemical shift reference.

[0137] Pulse width: 4*10.sup.−6 s, Recycle time: 60 s, Spinning rate: 4 kHz, No. of scans: 224.

Reference Example 1.5: Thermoanalysis DTA and TG

[0138] The Thermoanalysis DTA and data TG were collected using 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.

Example 1: Protocol for Preparation of the Layered Silicate According to the Invention

[0139]

TABLE-US-00001 Silica gel (11 weight-% H.sub.2O; 1.12 g synthesized as described below): Diethyldimethylammonium hydroxide 6.00 g (aqueous solution, 20 weight-%)

i) Preparation of the Silica Gel (11 Weight-% H.SUB.2.O)

[0140] Solution A: 235.9 ml tetraethylorthosilicate (Sigma) were mixed with 363.9 ml ethanol. Solution B: 0.09 g NH.sub.4F (95% weight-%, Merck) were dissolved in 36 ml H.sub.2O. Subsequently Solution B was dropwise added to solution A at around 23° C. This mixture was kept under static conditions at around 23° C. for 24 hours, providing a hydrous gel which was further heated at 70° C. for 3 d, then at 110° C. for 1 d and finally heated at 500° C. for 5 d. The resulting silica gel (a wet-process silica) was milled by hand in a mortar and then kept in an open beaker. The silica gel was characterized by powder XRD according to reference example 1.1, DTA/TG according to reference example 1.5 and .sup.23Si MAS NMR according to reference example 1.4. The powder XRD pattern showed only a very broad peak centered at 23° 2-theta. The .sup.23Si MAS NMR showed 3 signals at ca. −92.0 ppm (Q.sup.2-type), −102.3 ppm (Q.sup.3-type), 110.1 ppm (Q.sup.4-type) with approx. intensity ratios of 15%:70%:15%, respectively. TG showed a total weight loss (loss of H.sub.2O) of 11% occurring in two steps: a) between around 23° C. and 150° C. (9%) and b) in the range of 200° C. to 800° C. (2%).

ii) Preparation of the Layered Silicate According to the Invention

[0141] 1.12 g of the silica gel (11 weight-% H.sub.2O) prepared in i) were added to 6.00 g of the diethyldimethylammonium hydroxide solution. This mixture was stirred at around 23° C. for a time (T.sub.1—see Table 1 below). Subsequently, the mixture was heated in a vacuum oven at 70° C. and 20 mbar for a time (T.sub.2—see Table 1 below). During this treatment, an amount of water (A.sub.1—see Table 1 below) was removed from the mixture. The resulting mixture was then filled into a Teflon-lined steel autoclave, the autoclave sealed, then the autoclave was heated under static conditions to a temperature of at (X.sub.1—see Table 1 below) and kept at this temperature for a time (T.sub.3—see Table 1 below). After pressure release and cooling to around 23° C., the product was thoroughly washed with distilled water, until the washing water had a conductivity of less than 200 microSiemens. The thus obtained washed product (RUB-56) was then separated by centrifugation and dried in air at around 23° C. overnight. The composition of the inventive material per unit cell according to the crystal structure analysis was determined in view of the XRD data, said data being obtained as described in Reference Example 1.1. The composition of the inventive material per unit cell is as follows:

(C.sub.6H.sub.16N).sub.8[Si.sub.32O.sub.64(OH).sub.8]*24H.sub.2O

[0142] The XRD pattern, determined as described in Reference Example 1.1, is shown in FIG. 1. The structure was solved by comparison with the XRD powder data of ITQ-8 and by comparison with the FTIR spectrum of ITQ-8. The structure of RUB-56 was refined using the FullProf 2K program. The SEM picture, determined as described in Reference Example 1.3, is shown in FIG. 2. The (ATR) IR Spectrum, determined as described in Reference Example 1.4, is shown in FIG. 3. The .sup.29Si MAS NMR spectrum, determined as described in Reference Example 1.5, is shown in FIG. 4. The thermoanalysis DTA and TG, determined as described in Reference Example 1.6, is shown in FIG. 5.

Comparative Examples 1 to 5: Protocol for the Comparative Examples

[0143] For comparative examples 1 to 5, a similar protocol was employed based on that used for the inventive example, with the following modifications as summarized in Table 1. Unless otherwise indicated in Table 1, the same materials and amounts thereof were used as per (inventive) Example 1.

TABLE-US-00002 TABLE 1 Summary of the Inventive and the Comparative Examples Step Step (i.2) (i.1, time/ (iii) hydrothermal Molar Composition Silica-gel mixing amount synthesis conditions of synthesis mixture (11% time) H.sub.2O lost Temp/time obtained from H.sub.2O) (T.sub.1) (T.sub.2)/(A.sub.1) (X.sub.1)/(T.sub.3) step (i.2) Inventive Example Example 1 1.12 g 30 min 80 min/ 140° C./ 0.9 SiO.sub.2: (RUB-56) 2.4 g 48 h 0.5 DEDMA-OH: 6.7 H.sub.2O Comparative Examples Comparative 1.12 g 60 min 45 min/ 120° C./ 1.0 SiO.sub.2: Example 1 1.1 g 2 days 0.5 DEDMA-OH: (amorphous) 10 H.sub.2O Comparative 1.36 g (ca. 10 50 min/ 160° C./ 1.0 SiO.sub.2: Example 2 min) 1.3 g 7 days 0.5 DEDMA-OH: (RUB-36) (until 9.7 H.sub.2O uniform gel formed) Comparative 1.36 g (ca. 10 50 min/ 150° C./ 1.0 SiO.sub.2: Example 3 min) 1.3 g 11 days 0.5 DEDMA-OH: (RUB-36) (until 9.7 H.sub.2O uniform gel formed) Comparative 1.12 g 30 min 45 min/ 130° C./ 1.0 SiO.sub.2: Example 4 1.1 g 7 days 0.5 DEDMA-OH: (RUB-52) 10 H.sub.2O Comparative 1.12 g ca. 2 40 min/ 140° C./ 1.0 SiO.sub.2: Example 5 minutes 1.15 g 7 days 0.5 DEDMA-OH: (RUB-52) 10 H.sub.2O

[0144] As can readily be seen from Table 1, Comparative Example 1 demonstrates that when low synthesis temperatures are used for the hydrothermal synthesis conditions, then an amorphous material is obtained. Furthermore, from Table 1 it can be seen that RUB-36 forms at higher hydrothermal synthesis temperatures. Finally, when prolonged hydrothermal synthesis conditions were employed a different product, denoted as RUB-52, was obtained.

BRIEF DESCRIPTION OF THE FIGURES

[0145] FIG. 1: shows the XRD pattern of RUB-56 according to Example 1. On the y axis, the intensity (arbitrary units) is shown.

[0146] FIG. 2: shows the SEM picture of RUB-56 according to Example 1.

[0147] FIG. 3: shows the (ATR) IR Spectrum of RUB-56 according to Example 1.

[0148] FIG. 4: shows the .sup.29Si MAS NMR spectrum of RUB-56 according to Example 1, comprising Q.sup.3-type (−99 ppm and −101 ppm) and Q.sup.4-type (−106 and −108 ppm) signals.

[0149] FIG. 5: shows the thermoanalysis DTA and TG of RUB-56 according to Example 1.

[0150] FIG. 6: shows a schematic representation of the structure of RUB-56.

[0151] FIG. 7: shows the XRD pattern of the amorphous material according to Comparative Example 1.

[0152] FIG. 8: shows the XRD pattern of RUB-36 according to Comparative Example 2.

[0153] FIG. 9: shows the XRD pattern of RUB-36 according to Comparative Example 3, containing ca. 2% RUB-52 as an impurity (Peak at 5.8° 2-theta in the XRD pattern).

[0154] FIG. 10: shows the XRD pattern of RUB-52 according to Comparative Example 4.

[0155] FIG. 11: shows the XRD pattern of RUB-52 according to Comparative Example 5.

CITED LITERATURE

[0156] Bernd Marler, Melanie Müller, Hermann Gies: Structure and Properties of ITQ-8: A Hydrous Layer Silicate with Microporous Silicate Layers, Dalton Transactions 45, pages 10155-10164 (2016) [0157] Bernd Marler, H. Gies: Hydrous layer silicates as precursors for zeolites obtained through topotactic condensation: a review. Eur. J. Mineral, 24, pages 405-428 (2012)