Direct Synthesis of Aluminosilicate Zeolitic Materials of the IWR Framework Structure Type and their Use in Catalysis

Abstract

The present invention relates to a zeolitic material having the IWR type framework structure, wherein the zeolitic material comprises YO.sub.2 and X.sub.2O.sub.3 in its framework structure, wherein Y is a tetravalent element and X is a trivalent element, and wherein the framework structure of the zeolitic material comprises less than 5 weight-% weight-% of Ge calculated as GeO.sub.2 and based on 100 weight-% weight-% of YO.sub.2 contained in the framework structure, and less than 5 weight-% weight-% of B calculated as B.sub.2O.sub.3 and based on 100 weight-% weight-% of X.sub.2O.sub.3 contained in the framework structure. Further, the present invention relates to a process for preparing a zeo-litic material having the IWR type framework structure, wherein the zeolitic material comprises YO.sub.2 and X.sub.2O.sub.3 in its framework structure, wherein Y is a tetravalent element and X is a trivalent element.

Claims

1. A zeolitic material having the IWR type framework structure, wherein the zeolitic material comprises YO.sub.2 and X.sub.2O.sub.3 in its framework structure, wherein Y is a tetravalent element and X is a trivalent element, and wherein the framework structure of the zeolitic material comprises less than 5 weight-% of Ge calculated as GeO.sub.2 and based on 100 weight-% of YO.sub.2 contained in the framework structure, and less than 5 weight-% of B calculated as B.sub.2O.sub.3 and based on 100 weight-% of X.sub.2O.sub.3 contained in the framework structure.

2. The zeolitic material of claim 1, wherein the zeolitic material comprises less than 3 weight-% of Ge calculated as GeO.sub.2 and based on 100 weight-% of YO.sub.2 contained in the framework structure.

3. The zeolitic material of claim 1, wherein the zeolitic material comprises less than 3 weight-% of B calculated as B.sub.2O.sub.3 and based on 100 weight-% of X.sub.2O.sub.3 contained in the framework structure.

4. The zeolitic material of claim 1, wherein Y is selected from the group consisting of Si, Sn, Ti, Zr, and mixtures of two or more thereof.

5. The zeolitic material of claim 1, wherein X is selected from the group consisting of Al, In, Ga, Fe, and mixtures of two or more thereof.

6. The zeolitic material of claim 1, wherein the YO.sub.2:X.sub.2O.sub.3 molar ratio of the framework structure of the zeolitic material is in the range of from 5 to 1,000.

7. A process for the preparation of a zeolitic material having the IWR type framework structure, wherein the process comprises (1) preparing a mixture comprising one or more organotemplates as structure directing agents, one or more sources of YO.sub.2, one or more sources of X.sub.2O.sub.3, and a solvent system; (2) heating the mixture obtained in (1) for crystallizing a zeolitic material having the IWR type framework structure comprising YO.sub.2 and X.sub.2O.sub.3 in its framework structure; wherein the one or more organotemplates comprise an organodication of the formula (I):
R.sup.3R.sup.5R.sup.6N.sup.+—R.sup.1-Q-R.sup.2—N.sup.+R.sup.4R.sup.7R.sup.8   (I); wherein R.sup.1 and R.sup.2 independently from one another stand for (C.sub.1-C.sub.3)alkylene; wherein Q stands for C.sub.6-arylene; wherein R.sup.3 and R.sup.4 independently from one another stand for (C.sub.1-C.sub.4)alkyl; wherein R.sup.5, R.sup.6, R.sup.7, and R.sup.8 independently from one another stand for (C.sub.1-C.sub.6)alkyl.

8. The process of claim 7, wherein the alkyl groups R.sup.5 and R.sup.6 are bound to one another to form one common alkylene chain.

9. The process of claim 7, wherein the alkyl groups R.sup.7 and R.sup.8 are bound to one another to form one common alkylene chain.

10. The process of claim 7, wherein the organodication of the formula (I) has the formula (II): ##STR00003##

11. The process of claim 7, wherein Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and mixtures of two or more thereof.

12. The process of claim 7, wherein X is selected from the group consisting of Al, B, In, Ga, and mixtures of two or more thereof.

13. A zeolitic material obtainable and/or obtained from the process of claim 7.

14. A method for the conversion of oxygenates to olefins comprising (i) providing a catalyst according to claim 1; (ii) providing a gas stream comprising one or more oxygenates and optionally one or more olefins and/or optionally one or more hydrocarbons; (iii) contacting the catalyst provided in (i) with the gas stream provided in (ii) and converting one or more oxygenates to one or more olefins and optionally to one or more hydrocarbons; (iv) optionally recycling one or more of the one or more olefins and/or of the one or more hydrocarbons contained in the gas stream obtained in (iii) to (ii).

15. Use of a zeolitic material according to claim 13 as a molecular sieve, as an adsorbent, for ion-exchange, or as a catalyst and/or as a catalyst support.

Description

DESCRIPTION OF THE FIGURES

[0191] FIG. 1 displays the .sup.29Si MAS NMR spectrum of the as-synthesized Al-IWR-200 zeolite obtained according to Example 1.

[0192] FIG. 2 displays the XRD patterns of the aluminosilicate IWR zeolite obtained from starting gels with SiO.sub.2/Al.sub.2O.sub.3 ratios of (a) 30, (b) 150, and (c) 400, respectively.

[0193] FIG. 3 displays the .sup.27Al MAS NMR of the aluminosilicate IWR zeolite obtained from starting gels with SiO.sub.2/Al.sub.2O.sub.3 ratios of (a) 30 (Example 2), (b) 150 (Example 3), and (c) 400 (Example 4), respectively.

[0194] FIG. 4 displays the SEM images of the aluminosilicate IWR zeolite obtained from starting gels with SiO.sub.2/Al.sub.2O.sub.3 ratios of (a) 30 (Example 2), (b) 150 (Example 3), and (c) 400 (Example 4), respectively.

[0195] FIG. 5 displays the XRD patterns of the (a) Al-IWR-200, (b) H—Al-IWR-200, and (c) hydrothermally aged H—Al-IWR-200 zeolite as respectively obtained in Example 1.

[0196] FIG. 6 displays the XRD patterns of the (a) Ge—Al-IWR, (b) H—Ge—Al-IWR, and (c) hydrothermally aged H—Ge—Al-IWR zeolite as respectively obtained in Comparative Example 1.

[0197] FIG. 7 shows the dependencies of methanol conversion and product selectivities on the reaction time in MTO conducted in Example 10 over the H—Al-IWR-400 zeolite in the product at 480° C. (.square-solid.: conversion rate of methanol; .diamond-solid.: C1; Δ: C2; .box-tangle-solidup.: C2═; ⋆: C3; .star-solid.: C3═; ○: C4; .circle-solid. (black): C4═; .circle-solid. (dark grey): C5+).

[0198] FIG. 8 shows the dependencies of methanol conversion and product selectivities on reaction time in MTO conducted in Example 10 over the aluminosilicate ZSM-5 zeolite at 480° C. (.square-solid.: conversion rate of methanol; .diamond-solid.: C1; Δ: C2; .box-tangle-solidup.: C2═; ⋆: C3; .star-solid.: C3═; ○: C4; .circle-solid. (lower values): C4═; .circle-solid. (higher values): C5+).

EXPERIMENTAL

Characterization Via X-Ray Diffraction Analysis

[0199] X-ray powder diffraction (XRD) patterns were measured with a Rigaku Ultimate VI X-ray diffractometer (40 kV, 40 mA) using CuKα (λ=1.5406 Å) radiation.

Characterization Via Solid State NMR

[0200] Solid MAS NMR was performed on a Bruker AVANCE-III 400 spectrometer. Magic angle spinning (MAS) experiments were performed on 3.2 mm MAS probes at a spinning speed of 15 kHz. The .sup.27Al signals were referenced to 1 M Al(NO.sub.3).sub.3 solution at 0 ppm. The .sup.29Si signals were referenced to TMS at 0 ppm.

Characterization Via SEM and TEM

[0201] Scanning electron microscopy (SEM) experiments were performed on Hitachi SU-1510 electron microscopes. Transmission electron microscopy (TEM) experiments were conducted on a JEOL JEM-2100P at 200 kV.

Characterization of Surface Area and Porosity Characteristics

[0202] The N.sub.2 sorption isotherms at the temperature of liquid nitrogen were measured using Micromeritics ASAP 2020M and Tristar system.

Catalytic Testing in MTO

[0203] MTO reaction was performed in a fixed-bed reactor at an atmospheric pressure. The reaction temperature was at 480° C. The zeolite catalyst (0.50 g, 20-40 mesh) was pretreated in flowing nitrogen at 500° C. for 2 h and cooled down to reaction temperature. The methanol was injected into the catalyst bed by a pump with weight hourly space velocity (WHSV) of 1 h.sup.−1. The product was analyzed by online gas chromatography (Agilent 6890N) with FID detector using PLOT-Al.sub.2O.sub.3 column.

Materials For Synthesis

[0204] p-xylylene dibromide (C.sub.8H.sub.8Br.sub.2, 97%, Aladdin Chemistry Co., Ltd.), tetraethylorthosilicate (C.sub.8H.sub.20O.sub.4Si, TEOS, 99%, Aladdin Chemistry Co., Ltd.), hydrofluoric acid (HF, AR, 40%, Aladdin Chemistry Co., Ltd.), 1-methylpyrrolidine (C.sub.5H.sub.11N, 98%, Aladdin Chemistry Co., Ltd.), aluminum isopropoxide (C.sub.9H.sub.21O.sub.3Al, CP, Sinopharm Chemical Reagent Co., Ltd.), acetonitrile (C.sub.2H.sub.3N, AR, 99%, Sinopharm Chemical Reagent Co., Ltd.), germanium oxide (GeO.sub.2, 99.999%, Aladdin Chemistry Co., Ltd.), Beta zeolite (SiO.sub.2/Al.sub.2O.sub.3=27.4, Tianjing Nankai Catalysts Co., Ltd.), diethyldimethylammonium hydroxide solution (DEDMAOH, 25wt % in water, Kente Catalysts Inc.), sodium metaaluminate (NaAlO.sub.2, AR, 99%, Sinopharm Chemical Reagent Co., Ltd.), solid silica gel (SiO.sub.2, 98%, Qingdao Haiyang Chemical Reagent Co., Ltd.), sodium hydroxide (NaOH, AR, 96%, Sinopharm Chemical Reagent Co., Ltd.), colloidal silica (40 wt % SiO.sub.2 in water, Sigma-Aldrich Co., Ltd.), n-butylamine (C.sub.4H.sub.11N, Aladdin Chemistry Co., Ltd.).

Reference Example 1: Synthesis of p-xylylene-bis((N-methyl)N-pyrrolidinium) hydroxide

[0205] In a typical example for the synthesis of the organotemplate, 13.2 g p-xylylene dibromide was dissolved in 250 mL acetonitrile, then 10.6 g 1-methylpyrrolidine was added, stirring for 48 h under reflux. After cooling to the room temperature, the mixture was filtrated and washed with acetonitrile three times. The solid was dried under vacuum condition overnight. The bromide cation was converted to hydroxide form using hydroxide exchange resin in water, and the obtained solution was titrated using 0.1 M HCl as titration.

Comparative Example 1: Synthesis of an Germanosilicate Zeolite Having an IWR Type Framework Structure

[0206] In a typical example for the synthesis of Ge—Al-IWR zeolite, tetraethylorthosilicate (TEOS) was added into the solution of diethyldimethylammonium hydroxide solution (DEDMAOH, 25 wt % in water) in the 25 mL beaker, then germanium oxide and Beta zeolite (SiO.sub.2/Al.sub.2O.sub.3=27.4, used as an aluminum source) were added one by one into above solution. After stirring overnight, the excess water and ethanol were evaporated, it was obtained a mixture with the molar ratio composition at 0.5 DEDMAOH:SiO.sub.2:0.5 GeO.sub.2:0.007 Al.sub.2O.sub.3:5.5 H.sub.2O. The gel was transferred into Teflon line, sealed in a stainless steel autoclave, and then placed in a rotating oven and heated at 175° C. for 7 days. The final products were filtrated, washed with deionized water and dried overnight at 100° C. This sample was designated as Ge—Al-IWR. The organic template in the product was removed by calcining at 550° C. for 5 h in air. The calcined product was denoted as H—Ge—Al-IWR. After hydrothermal treatment of H—Ge—Al-IWR zeolite product at 800° C. with 10% H.sub.2O for 4 h, the aged H—Ge—Al-IWR zeolite product was obtained.

Comparative Example 2: Synthesis of ZSM-5 Zeolite Having an MFI Type Framework Structure

[0207] In a typical example for the synthesis of aluminosilicate ZSM-5 zeolite, 0.14 g of NaOH and 0.007 g of NaAlO.sub.2 were dissolved in 4.5 g of deionized water. After stirring for 0.5 h, 0.365 g of n-butylamine was added into the above gel, followed by the addition of 1.0 g of solid silica gel. After stirring for another 2 h, the final gel was transferred into Teflon line, sealed in a stainless steel autoclave, and crystallized at 140° C. for 2 days. The solids were filtrated, washed with deionized water, dried overnight at 100° C. The sample was calcined at 550° C. for 5 h to remove organic template. The H-form of the product (H-ZSM-5) was prepared by ion-exchange with 1.0 M NH.sub.4Cl solution three times and calcination at 450° C. for 4 h.

Example 1: Direct Synthesis of an Aluminosilicate Zeolite Having an IWR Type Framework Structure

[0208] In a typical example for the synthesis of Al-IWR zeolite, tetraethylorthosilicate (TEOS) was added into a solution of p-xylylene-bis((N-methyl)N-pyrrolidinium) hydroxide in a 25 mL beaker, and then aluminum isopropoxide was added to this mixture. After stirring for 12 h, a clear solution was formed. After hydrofluoric acid was added to the above solution, the beaker was put into oven with the temperature of 80° C. for evaporating excess water and ethanol, the final molar compositions of the mixtures were 1.0 SiO.sub.2:0.25 OSDA1:x Al.sub.2O.sub.3:0.5 HF:2 H.sub.2O. At last, 6% of pure silica IWR seeds (mass ratios of seeds to the silica source) was added to the above mixtures and then the mixtures were ground. After grinding, the powder was transferred into Teflon line and sealed, crystallizing at 160° C. for 72 h under rotation condition (50 rpm). The final product was obtained by filtering, washing with deionized water, and subsequently drying overnight at 100° C. These samples were designated as Al-IWR-1/x. The organic template in the product was removed by calcining in air at 550° C. for 5 h. The calcined product was denoted as H—Al-IWR-1/x. After hydrothermal treatment of H—Al-IWR-200 zeolite at 800° C. with 10% H.sub.2O for 4 h, the aged H—Al-IWR-1/x zeolite product was obtained.

[0209] As a typical example, the as-synthesized aluminosilicate IWR zeolite with the ratio of SiO.sub.2/Al.sub.2O.sub.3 ratio at 200 in the starting gel is investigated. The X-ray diffraction pattern of the as-synthesized Al-IWR-200 zeolite shows a series of characteristic peaks associated with IWR structure, which are in good agreement with those of simulated XRD pattern of the IWR zeolite. N.sub.2 sorption isotherms of the H—Al-IWR-200 zeolite product afford a BET surface area of 580 m.sup.2/g and a micropore volume of 0.27 cm.sup.3/g, which are higher than those of corresponding germanosilicate IWR zeolite These results should be related to the difference in thermal stability, where that aluminosilicate IWR zeolite is stable for calcination at 550° C., while germanosilicate IWR zeolite might be partially destroyed by the same calcination. Inductively coupled plasma (ICP) analysis of Si/Al of the Al-IWR zeolite affords a value of 85, corresponding to a silica to alumina molar ratio of 170.

[0210] In FIG. 1, the .sup.29Si MAS NMR spectrum of the as-synthesized Al-IWR-200 zeolite is displayed, showing peaks with the chemical shift at −113.8, −106.8, and −100.6 ppm associated with Si(4Si), Si(4Si), and Si(3Si) respectively. The .sup.27Al MAS NMR spectrum of the as-synthesized aluminosilicate zeolite exhibits one signal with the chemical shift at 56.5 ppm associated with aluminum in the zeolite framework. This result demonstrates that all of the aluminum species have been successfully incorporated into the framework of IWR zeolite.

Examples 2-4: Direct Synthesis of an Aluminosilicate Zeolites Having an IWR Type Framework Structure With Varying Silica to Alumina Ratios of the Synthesis Gel

[0211] Example 1 was repeated, wherein the SiO.sub.2/Al.sub.2O.sub.3 ratios of 30 (Example 2), 150 (Example 3), and 400 (Example 4) were respectively used in the starting gels for the synthesis of aluminosilicate IWR zeolite. FIGS. 2 to 4 exhibit XRD patterns (FIG. 2), .sup.27Al MAS NMR spectra (FIG. 3), and SEM images (FIG. 4) of aluminosilicate IWR zeolites with the aforementioned different SiO.sub.2/Al.sub.2O.sub.3 ratios in the starting gels, showing that all of the products have very high crystallinity. More specifically, the aforementioned SEM images display that all of the products have perfect crystalline morphology; the aforementioned .sup.27Al MAS NMR spectra exhibit that all of the products have only a single peak with the chemical shift at 56.5 ppm associated with the signals of tetravalently-coordinated aluminum species. Results from ICP analysis displayed in Table 1 show that the SiO.sub.2/Al.sub.2O.sub.3 ratios of the obtained products are close to those of the respective starting gels. Notably, considering the theoretical ratio of SiO.sub.2/Al.sub.2O.sub.3 in this aluminosilicate zeolite of at least at 26, it is noted that the direct synthesis of aluminosilicate IWR zeolite according to the present invention almost realizes the minimum of SiO.sub.2/Al.sub.2O.sub.3 (see Table 1: SAR=30 for Example 2).

Examples 5-7: Direct Synthesis of Aluminosilicate Zeolites Having an IWR Type Framework Structure With Varying H.SUB.2.O/SiO.SUB.2 .Ratios of the Synthesis Gel

[0212] In the synthesis of aluminosilicate IWR zeolite, it is found that the addition of all silica IWR zeolite seeds and the ratio of H.sub.2O/SiO.sub.2 in the starting gel strongly influence the crystallization (see Table 1). Thus, Example 1 was repeated, wherein the H.sub.2O/SiO.sub.2 ratios of 10 (Example 5), 5 (Example 6), and 1 (Example 7) were respectively used in the starting gels for the synthesis of aluminosilicate IWR zeolite. Furthermore, when the ratio of H.sub.2O/SiO.sub.2 is 10.0, a zeolitic material of the MTW type framework structure is obtained as the main product (see Example 5 in Table 1); when the ratio of H.sub.2O/SiO.sub.2 is ranged from 1.0 to 5.0, the aluminosilicate IWR zeolites successfully synthesized (see Examples 6 and 7 in Table 1).

[0213] Example 8: Direct Synthesis of Aluminosilicate Zeolites Having an IWR Type Framework Structure Without Seeds in the Synthesis Gel

[0214] Example 1 was repeated, wherein no seeding material was added to the synthesis gel. In general when the IWR zeolite seeds are added, a product with high crystallinity is obtained. When the IWR zeolite seeds are not employed in the reaction mixture, a layered material is obtained in addition to the zeolitic material of the IWR type framework structure (see Example 8 in Table 1).

TABLE-US-00001 TABLE 1 Reaction mixture compositions and characterization of the crystallization products for Examples 1 to 8 SiO.sub.2/ H.sub.2O/ ICP Run.sup.a Al.sub.2O.sub.3 SiO.sub.2 Seeds.sup.b (%) Products.sup.c (SiO.sub.2/Al.sub.2O.sub.3) Example 1 200 2 6 IWR 170 Example 2 30 2 6 IWR 30 Example 3 150 2 6 IWR 120 Example 4 400 2 6 IWR 270 Example 5 200 10 6 MTW Example 6 200 5 6 IWR Example 7 200 1 6 IWR Example 8 200 2 0 Layer + IWR .sup.aCrystallized at 160° C. for 72 h under rotation condition (50 rpm), organotemplate/SiO.sub.2 = 0.25, and HF/SiO.sub.2 = 0.5. .sup.bMass ratios of seeds to the silica source. .sup.cThe phase appearing first is dominant.

Example 9: Aging and Hydrothermal Testing Experiments

[0215] It is well known that the hydrothermal and thermal stabilities of zeolites are very important for catalytic applications. In general, the stability of aluminosilicate zeolite is much better than that of the germanosilicate zeolite containing aluminum, which was confirmed by the present experiments. Both of the as-synthesized Al-IWR-200 zeolite with the SiO.sub.2/Al.sub.2O.sub.3 ratio of 170 according to Example 1 and the as-synthesized Ge—Al-IWR zeolite with the (GeO.sub.2+SiO.sub.2)/Al.sub.2O.sub.3 ratio of 196 prepared in Comparative Example 1 were calcined at 550° C. for 5 h. Very interestingly, although both show good crystallinity, the BET surface area and micropore volume are quite different. More specifically, the H—Ge—Al-IWR zeolite affords a BET surface area of 435 m.sup.2/g and a micropore volume of 0.17 cm.sup.3/g, which are lower than those of H—Al-IWR-200 zeolite (580 m.sup.2/g and 0.27 cm.sup.3/g). The lower BET surface area and micropore volume are mainly attributed to the micropore channel plugging by germanium removed from the zeolite framework at relatively high temperature. In addition, hydrothermal treatment of above two zeolites was performed at 800° C. with 10% H.sub.2O for 4 h, leading to a significant decrease of the H—Ge—Al-IWR zeolite crystallinity (see FIG. 5). In contrast, the same treatment did not substantially change for the H—Al—IWR-200 zeolite crystallinity (see FIG. 6). Correspondingly, the BET surface area and micropore volume of H—Ge—Al-IWR zeolite (154 m.sup.2/g and 0.06 cm.sup.3/g) are much lower than those (511 m.sup.2/g and 0.21 cm.sup.3/g) of H—Al-IWR-200 zeolite. From the aforementioned results, it is concluded that the aluminosilicate IWR zeolite has much better hydrothermal and thermal stability than germanosilicate IWR zeolite. For an overview, the results from the measurement of the surface area and pore volume are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Textural parameters of the IWR zeolites before and after hydrothermal treatments. Surface Pore volume area (m.sup.2/g) (cm.sup.3/g) Run Treatment T/Al.sup.c S.sub.BET S.sub.Micro V.sub.total V.sub.Micro Ex. 1.sup.a Calcined 85 580 574 0.33 0.27 Ex. 1.sup.a Aging 511 446 0.32 0.21 Comp. Ex. 1.sup.b Calcined 98 435 379 0.32 0.17 Comp. Ex. 1.sup.b Aging 154 136 0.19 0.06 .sup.aH-Al-IWR-200 zeolite. .sup.bH-Ge-Al-IWR zeolite. .sup.cThe molar ratios of T/Al (T = Si and Ge) were detected by ICP analysis.

Example 10: MTO Testing

[0216] FIGS. 7 and 8 show catalytic conversions and product selectivities in the MTO reaction over the H—Al-IWR-400 zeolite from Example 4 and the H-ZSM-5 zeolite from Comparative Example 2 which have similar Si/Al ratios. Table 3 shows the results of reactions for 4 h. Clearly, the H—Al-IWR-400 zeolite exhibits a higher selectivity for propene and higher propene/ethene ratios than H-ZSM-5 zeolite, which is potentially important for the selective production of propylene in the industrial applications.

TABLE-US-00003 TABLE 3 Results from MTO testing at a reaction time of 4 hours at 480° C. Conv. Selectivities (%) Sample SiO.sub.2/Al.sub.2O.sub.3 (%) C.sub.2 C.sub.3 C.sub.3/C.sub.2 H-AI-IWR- 270 100  4.6 47.0 10.2 400 H-ZSM-5 242 100 15.3 41.1  2.7
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