EPOXIDATION CATALYST AND PROCESS FOR ITS PREPARATION

Abstract

The present invention relates to a specific process for the preparation of a zeolitic material, wherein the framework structure of the zeolitic material comprises Si, O, and a tetravalent ele-ment M other than Si, wherein M is selected from the group consisting of Ti, Sn, Zr, Ge, and mixtures of two or more thereof. Further, the present invention relates to a zeolitic material obtainable or obtained by said process, the zeolitic material itself and its use. In addition thereto, the present invention relates to a molding comprising said zeolitic material.

Claims

1.-15. (canceled)

16. A process for the production of a zeolitic material, wherein the framework structure of the zeolitic material comprises Si, O, and a tetravalent element M other than Si, wherein M is selected from the group consisting of Ti, Sn, Zr, Ge, and mixtures of two or more thereof, the process comprising: (1) preparing a mixture comprising one or more sources of MO.sub.2, one or more organotemplates, a first portion of one or more sources of SiO.sub.2, and a protic solvent system comprising water; (2) heating the mixture obtained in (1) at a temperature comprised in the range of from 30? C. to the boiling point of the mixture; (3) heating the mixture obtained in (2) under autogenous pressure at a temperature comprised in the range of from 100 to 250? C.; wherein during the course of (2), a second portion of one or more sources of SiO.sub.2 is added to the mixture.

17. The process of claim 16, wherein M is selected from the group consisting of Ti, Sn, and a mixture thereof.

18. The process of claim 16, wherein heating in (2) is conducted continuously or intermittently.

19. The process of claim 18, wherein heating in (2) is conducted intermittently, wherein the heating consists of two or more heating phases, wherein the second portion of one or more sources of SiO.sub.2 is added during the one or more intervals in between the two or more heating phases.

20. The process of claim 18, wherein heating consists of 2 to 6 heating phases.

21. The process of claim 16, wherein the first portion of one or more sources of SiO.sub.2 comprises an amount in the range of from 45 to 90 mol-% of the total amount (100 mol.-%) of the one or more sources of SiO.sub.2, calculated as SiO.sub.2, added to the mixture in (1) and during the course of (2).

22. The process of claim 16, wherein the second portion of one or more sources of SiO.sub.2 comprises an amount in the range of from 10 to 55 mol-% of the total amount (100 mol.-%) of the one or more sources of SiO.sub.2, calculated as SiO.sub.2, added to the mixture in (1) and during the course of (2).

23. The process of claim 16, further comprising one or more of (4) isolating the zeolitic material obtained in (3); (5) optionally washing the zeolitic material obtained in (3) or (4); (6) drying the zeolitic material obtained in (3), (4) or (5); (7) calcining the zeolitic material obtained in (3), (4), (5) or (6).

24. A zeolitic material obtained by the process according to claim 16.

25. A zeolitic material, wherein the framework structure of the zeolitic material comprises Si, O, and a tetravalent element M other than Si, wherein M is selected from the group consisting of Ti, Sn, Zr, Ge, and mixtures of two or more thereof, and wherein the UV-vis spectrum of the zeolitic material displays a first absorption band A1 having a maximum in the range of from 180 to 230 nm, and a second absorption band A2 having a maximum in the range of from 290 to 370 nm.

26. The zeolitic material of claim 25, wherein the UV-vis spectrum displays no further maximum between the maximum of the first absorption band and the maximum of the second absorption band.

27. The zeolitic material of claim 25, wherein the FTIR spectrum of the zeolitic material displays a first absorption band B1 having a maximum in the range of from 3,450 to 3,550 cm.sup.?1, and a second absorption band B2 having a maximum in the range of from 3,700 to 3,775 cm.sup.?1, wherein the intensity ratio B1:B2 of the first absorption band to the second absorption band is comprised in the range of from 0.70:1 to 0.90:1.

28. A process for preparing a molding, comprising: (A) providing a zeolitic material according to claim 24; (B) mixing the zeolitic material provided in step (A) with one or more binders; (C) optionally kneading of the mixture obtained in step (B); (D) molding of the mixture obtained in step (B) or (C) to obtain one or more moldings; (E) drying of the one or more moldings obtained in step (D); and (F) calcining of the dried molding obtained in step (E).

29. A molding obtained by the process of claim 28.

30. A method comprising utilizing a zeolitic material according to claim 24 as a catalyst, catalyst component, absorbent, adsorbent, or for ion exchange.

Description

DESCRIPTION OF THE FIGURES

[0136] FIG. 1: shows the XRD of the zeolitic materials of Example 1 and Comparative Example 1. The 2theta angle in degree is shown on the abscissa and the intensity is shown on the ordinate in arbitrary units.

[0137] FIGS. 2A and 2B: show the SEM images of the zeolitic materials of Comparative Example 1 and Example 1, respectively.

[0138] FIG. 3: shows the UV-vis spectra of the zeolitic materials of Example 1 and Comparative Example 1. The wavelength in nm is shown on the abscissa and the absorbance is shown in arbitrary units on the ordinate.

[0139] FIG. 4: shows the FT-IR spectra of the zeolitic materials of Example 1 and Comparative Example 1. The wavenumber in cm-1 is shown on the abscissa and the absorbance is shown in arbitrary units on the ordinate. An absorbance band having a maximum wavenumber in the range of from 3740 to 3725 cm-1 can be attributed to external and internal SiOH groups whereas an absorbance band having a maximum wavenumber at about 3500 cm-1 can be attributed to a SiOH nest.

EXPERIMENTAL SECTION

Reference Example 1: Determination Methods

Reference Example 1.1: Determination of XRD Diffraction Spectra

[0140] X-ray powder diffraction (XRD) was performed on a Rint-Ultima III (Rigaku) instrument using a Cu Kalpha radiation (Lambda=1.5406 angstrom, 40 kV, 40 mA).

Reference Example 1.2: Determination of Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

[0141] Elemental analyses were performed on an inductively coupled plasma-atomic emission spectrometer (ICP-AES, Shimadzu ICPE-9000). The samples were dissolved in dilute HF solutions.

Reference Example 1.3: Determination of N2 Adsorption-Desorption Measurements

[0142] Nitrogen adsorption-desorption measurements were performed on a BEL-mini analyzer, BEL Japan. Prior to the measurements, all samples were degassed at 350? C. for 2 h.

Reference Example 1.4: Determination of Water Adsorption

[0143] Determination of the water adsorption properties of the examples of the experimental section was performed on a BEL-mini analyzer (BEL Japan) at 25? C. Before a measurement was started, residual moisture of a sample was removed by degassing of the sample at 350? C. for 2 h. The water adsorption of a sample was taken after the sample was exposed to a relative humidity of 91%.

Reference Example 1.5: Determination of Temperature Programmed Desorption of Ammonia (NH.SUB.3.-TPD)

[0144] Temperature-programmed desorption of ammonia (NH.sub.3-TPD) profiles were recorded on a Multitrack TPD equipment (JapanBEL) using ca. 30 mg of a sample.

Reference Example 1.6: Determination of NMR Spectra

[0145] The high-resolution 29Si MAS NMR spectra were obtained on a JEOL ECA-600 spectrometer.

Reference Example 1.7: Determination of IR Spectra

[0146] FTIR spectra were collected on a JASCO FT-IR 4100 spectrometer. Typically, the H-form samples were pressed into a self-supporting wafer (20 mm diameter, 30?2 mg) and placed in an IR cell, where it was pretreated by evacuation at 723 K for 1 h. After this, the temperature was decreased to 423 K and the spectrum was recorded.

Reference Example 1.8: Determination of UV-Vis Spectra

[0147] The UV-visible diffuse reflectance spectra were recorded on the V-650DS spectrometer (JASCO) using BaSO.sub.4 as a reference.

Reference Example 1.9: Scanning Electron Microscopy (SEM)

[0148] Field-emission scanning electron microscopy (FE-SEM) were obtained on a Hitachi S-5200 microscope.

Example 1: Preparation of a Zeolitic Material According to the Present Invention

[0149] Tetraethyl orthosilicate (TEOS, Wako, 97%) and titanium tetra-n-butoxide (TBOT, Wako, at least 95.0%) were used as Si and Ti sources, respectively. Tetrapropylammonium hydroxide (TPAOH, TCI, 40% in water) was used as organic structure directing agent (OSDA), and deionized water (Wako, 20 L) was used.

[0150] In a typical synthesis, 0.119 g TBOT was mixed with 1.43 g TEOS (? of the total amount) and the mixture added to 0.61 g of an aqueous solution comprising 40 weight-% TPAOH and 2.87 g H.sub.2O. The resulting gel mixture had the following molar ratio: 1 Si: 0.0033 Ti: 0.12 TPAOH: 16 H.sub.2O. Next, the gel mixture was put in an oven, stirred at 50? C. for 30 min and then at 80? C. for 2 h for hydrolysis of TEOS and TBOT, whereby the formed alcohol was removed. After this hydrolysis process, 0.72 g TEOS (? of the total amount) was added into the gel mixture and the above described hydrolysis process was repeated again, i.e. the gel mixture was put in the oven, stirred at 50? C. for 30 min and then at 80? C. for 2 h. After said steps of hydrolysis, the gel mixture was hydrothermally treated in a 20 mL autoclave with Teflon-inner at 170? C. for 2 days under tumbling condition (40 rpm). The obtained products were collected and washed with distilled water and dried at 100? C. overnight. The as-made samples were calcined at 550? C. for 6 h in air to remove the OSDA. The water adsorption of the obtained zeolitic material was 14.3 weight-%. Further, characteristics of the obtained zeolitic material are noted in Table 1 in Reference Example 2 below.

Comparative Example 1: Preparation of a Zeolitic Material not in Accordance with the Present Invention

[0151] For the gel preparation, 500 g tetraethylorthosilicate (TEOS) and 15 g tetraethylorthotitanate (TEOTi; Merck) were filled into a beaker. Then, a solution of 300 g de-ionized water and 220 g aqueous tetrapropylammonium hydroxide (TPAOH; 40 weight-% in water) was added under stirring (200 rpm). The resulting mixture had a pH of 13.5. The mixture was hydrolyzed at room temperature for 60 min during which the temperature rose to 60? C. The mixture had a pH of 12.6 then. Afterwards the ethanol was distilled off until the sump reached a temperature of 95? C. 540 g of distillate was obtained from distillation.

[0152] The synthesis gel was then cooled to 40? C. under stirring and 542 g de-ionized water added thereto. The resulting mixture had a pH of 11.9.

[0153] The synthesis gel was then transferred into an autoclave. The synthesis gel was heated under stirring in the autoclave to a temperature of 175? C. and stirred at said temperature for 16 h under autogenous pressure. The pressure was in the range of from 8.4 to 10.9 bar (abs). The resulting suspension was then worked-up. To this effect, the resulting suspension was diluted with de-ionized water, wherein the weight ratio of the suspension to de-ionized water was 1:1. Then, about 164 g nitric acid (10 weight-% in water) were added and the resulting mixture had a pH of 7.35. The obtained solids were filtered off and washed four times with de-ionized water (each time 1000 ml de-ionized water were used). Subsequently, the solids were dried in an oven in air at 120? C. for 16 h and then calcined in air at 490? C. for 5 h, wherein the heating rate for calcining was 2? C./min.

[0154] The thus obtained TS-1 material had a Si content of 43 weight-%, a Ti content of 2 weight-% and a total loss of carbon of less than 0.1 weight-%. The water adsorption was 15.3 weight-%. The crystallinity was 88% as determined by X-ray diffraction.

Reference Example 2: Characteristics of the Zeolitic Materials According to Example 1 and Comparative Example 1

[0155]

TABLE-US-00001 TABLE 1 Characteristics of the zeolitic materials of Example 1, and Comparative Example 1. Maxima of abs. Total amout bands B1 and B2 Si/Ti S.sub.BET V.sub.micro of acid sites in FT-IR Intensity ratio of sample [mol:mol] [m.sup.2 g.sup.?1] [cm.sup.3 g.sup.?1] [mmol g.sup.?1] [cm.sup.?1] B1:B2 Comp. 38 449 0.188 0.037 B2: 3735; 0.62:0.82 = Ex. 1 B1: 3516 0.76 Example 44 439 0.192 0.049 B2: 3726; 0.83:0.95 = 1 B1: 3516 0.87

Example 3: Catalytic Testing-Propylene Epoxidation

[0156] Propylene epoxidation was carried out in an autoclave reactor with a 100 mL Teflon-inner. The autoclave reactor was equipped with a water cooling system, an agitator blade, and a pressure gauge ranging from 0.5 to 3 MPa. Typically, 100 mg catalyst, 8.1 mL methanol, 30 mmol H.sub.2O2 (35 weight-%, containing 1.9 mL H.sub.2O) were added into the reactor. Next, propylene was charged into the autoclave at 0.2 MPa for three times to replace the air inside. The propylene pressure inside the autoclave was maintained at 0.4 MPa during the reaction. The reaction mixture was stirred at 120 rpm and heated to 333 K at 8? C./min. After holding at 333 K for 1 h, the stirring and heating of the autoclave were stopped and the Teflon-inner was taken out and cooled down to room temperature rapidly in an ice bath.

[0157] Then, the resulting liquid products were separated from the solids by injection filtration, and determined by a gas chromatograph (Shimadzu GC-14B) equipped with an DB-WAX column (60 m, 0.25 mm diameter, 0.25 ?m film) and FID detector, using DMF as internal standard. The amount of unconverted H.sub.2O2 was determined by standard titration method with 0.1 M Ce (SO.sub.4).sub.2 solution.

[0158] The results of the catalytic testing are shown in Table 2 below for the zeolitic materials of Example 1 and Comparative Example 1.

TABLE-US-00002 TABLE 2 Results of the catalytic testing in the epoxidation of propylene to propylene oxide. Sample n mmol Yield % Sel. % H.sub.2O.sub.2 No. PO PG BP-1 BP-2 PO PG BP-1 BP-2 PO PG BP-1 BP-2 Conv. Eff. Comp. 3.2 1.3 3.4 6.3 10.8 4.3 11.2 21.0 22.8 9.1 23.7 44.4 37 128 Ex. 1 Ex. 1 5.3 3.1 5.4 10.0 17.5 10.2 18.0 33.3 22.1 12.9 22.8 42.2 69 114

[0159] The following formulas were used for calculating the respective data:

[00001]$Y_{\mathrm{PO}}=\frac{n_{\mathrm{PO}}}{n_{H2O2}^0}$$Y_{\mathrm{PG}}=\frac{n_{\mathrm{PG}}}{n_{H2O2}^0}$${\mathrm{Eff}}_{H2O2}=\frac{n_{\mathrm{PO}}+n_{\mathrm{PG}}+n_{\mathrm{byproduct}}}{{\mathrm{Conv}}_{H2O2}.Math.n_{H2O2}^0}$$S_{\mathrm{PO}}=\frac{n_{\mathrm{PO}}}{n_{\mathrm{PO}}+n_{\mathrm{PG}}+n_{\mathrm{byproduct}}}$$S_{\mathrm{PG}}=\frac{n_{\mathrm{PG}}}{n_{\mathrm{PG}}+n_{\mathrm{PO}}+n_{\mathrm{byproduct}}}$${\mathrm{Conv}}_{H2O2}=\frac{n_{H2O2}^0-n_{H2O2}}{n_{H2O2}^0}$

[0160] n.sub.H2O2.sup.O and N.sub.H2O2 are the amount (mmol) of H.sub.2O.sub.2 before and after reaction, respectively;

n.sub.PO, n.sub.PG, and n.sub.byproduct are the amount (mmol) of propylene oxide, propylene glycol, and byproducts after reaction;
byproducts are designated as BP, wherein BP-1 is 1-methoxy-2-propanol and BP-2 is 2-methoxy-propan-1-ol.

[0161] As can be seen from the results, the zeolitic materials in accordance with Example 1 achieved a comparatively higher yield of propylene oxide (PO) and also a higher conversion of H.sub.2O2. In particular, the zeolitic material of Example 1 showed an outstanding yield of propylene oxide.

CITED PRIOR ART

[0162] WO 2011/064191 A1 [0163] WO 2021/123227 A1 [0164] WO 2020/221683 A1 [0165] WO 2020/074586 A1 [0166] Xiujuan Deng et al (Low-Cost Synthesis of Titanium Silicalite-1 (TS-1) with Highly Catalytic Oxidation Performance through a Controlled Hydrolysis Process, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, vol. 52, no. 3, 23 Jan. 2013 (2013-01-23), pages 1190-1196) [0167] Zhang Jian Hui et al (Synthesis of nanosized TS-1 zeolites through solid transformation method with unprecedented low usage of tetrapropylammonium hydroxide, MICROPOROUS AND MESOPOROUS MATERIALS, vol. 217, pages 96-101)