Synthesis of aluminiferous molecular sieve SSZ-60

Abstract

A process for preparing an aluminosilicate molecular sieve having an SSY framework structure is described. The present invention relates to a method for producing an aluminosilicate zeolite, the method comprising: (1) a step of preparing a reaction mixture containing an aluminosilicate zeolite having a FAU framework type, an N-ethyl-N-(3, 3, 5-trimethylcyclohexyl) pyrrolidinium cation and / or an N-ethyl-N-(2, 4, 4-trimethylcyclopentyl) pyrrolidinium cation, an alkali metal, a hydroxide ion, a seed crystal, and water; and (2) a step of subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve. The resulting molecular sieves are useful as catalysts, particularly when used in combination with exchanged transition metals.

Description

Technical Field

[0001] The present disclosure relates to the synthesis of crystalline aluminosilicate molecular sieves having an SSY framework structure, such as SSZ-60. Background Art

[0002] Molecular sieves are a class of porous materials with a regular inorganic framework structure and multiple pores or channels of defined size defined therein. The pore or channel size varies from one molecular sieve to another and determines the width of molecules that can enter the interior of a particular molecular sieve. Due to their defined microporosity and the molecular specificity obtained thereby, molecular sieves are often particularly useful for adsorption, ion exchange, gas separation and catalyst applications.

[0003] Molecular sieves are classified by the Structure Commission of the International Zeolite Association according to the IUPAC Commission Nomenclature for Zeolites. According to this classification, framework-type zeolites and other crystalline microporous molecular sieves of established structure are assigned unique three-letter codes. The various molecular sieve framework structures recognized by the Structure Commission of the International Zeolite Association are stored in a structure database accessible through http: / / www.iza-structure.org / databases.

[0004] SSZ-60 is a molecular sieve material with a unique one-dimensional channel system whose pores are defined by twelve rings. The structure of SSZ-60 can be derived by modifying the framework of ZSM-23 (MTT) with one-dimensional 10-ring pores. The framework structure of SSZ-60 has been assigned the three-letter code SSY by the Structure Committee of the International Zeolite Association.

[0005] The composition and characterizing X-ray diffraction pattern of SSZ-60 are disclosed in U.S. Pat. No. 6,620,401, which also describes the synthesis of the molecular sieve in the presence of a structure directing agent comprising an N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation or an N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation.

[0006] SSZ-60 is usually prepared directly as borosilicate. However, the catalytic activity of borosilicate molecular sieves is not sufficient to be suitable for some hydrocarbon conversion processes. The catalytic activity of molecular sieves can be improved by replacing the boron in the molecular sieve framework with aluminum through post-synthesis treatment methods.

[0007] According to the present disclosure, a method for the direct synthesis of aluminosilicate SSZ-60 (Al-SSZ-60) is provided, thereby avoiding additional post-synthesis processing steps. In addition, the crystallographic T-site positions of the framework aluminum atoms in the Al-SSZ-60 material using the direct method described herein may be different from those of the aluminum-containing SSZ-60 material prepared by conventional post-synthesis aluminum exchange methods. Summary of the invention

[0008] In one aspect, a method for synthesizing an aluminosilicate molecular sieve having an SSY framework is provided, the method comprising: (1) preparing a reaction mixture comprising: (a) an aluminum source and a silicon source, wherein both the aluminum source and the silicon source are aluminosilicate zeolites having a FAU framework; (b) a structure directing agent [Q] comprising an N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation and / or an N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation; (c) an alkali metal [M] source; (d) a hydroxide ion source; (e) seed crystals; and (f) water; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

[0009] In another aspect, an aluminosilicate molecular sieve is provided, which has an SSY framework and, in its as-prepared form, has N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cations and / or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cations within its pore structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The powder X-ray diffraction (XRD) pattern of the as-prepared product of Example 3 is shown.

[0011] Figure 2 The scanning electron microscope (SEM) image of the original product after preparation of Example 3 is shown.

[0012] Figure 3 It is a graph illustrating the relationship between the conversion rate or yield and the temperature when n-decane is hydrogenated over a Pd / Al-SSZ-60 catalyst. DETAILED DESCRIPTION

[0013] Glossary

[0014] The term "SSY" refers to an SSY-type topology or framework as recognized by the International Zeolite Association (IZA) Structure Commission.

[0015] The term "FAU" refers to the FAU type framework recognized by the IZA Structure Commission, and the term "FAU zeolite" means an aluminosilicate in which the major crystalline phase is FAU.

[0016] Reaction mixture

[0017] Generally speaking, an aluminosilicate molecular sieve having an SSY framework can be synthesized by the following steps: (1) preparing a reaction mixture comprising: (a) an aluminum source and a silicon source, wherein both the aluminum source and the silicon source are aluminosilicate zeolites having a FAU framework; (b) a structure directing agent [Q] comprising an N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation and / or an N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation; (c) an alkali metal [M] source; (d) a hydroxide ion source; (e) seed crystals; and (f) water; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

[0018] The reaction mixture may have a composition in terms of molar ratio within the range shown in Table 1.

[0019] Table 1

[0020] Reactants efficient Exemplary <![CDATA[SiO2 / Al2O3]]> 20 to 200 30 to 100 <![CDATA[OSDA / SiO2]]> 0.05 to 0.50 0.15 to 0.40 <![CDATA[M / SiO2]]> 0.10 to 0.80 0.20 to 0.50 <![CDATA[OH / SiO2]]> 0.10 to 1.0 0.20 to 0.80 <![CDATA[H2O / SiO2]]> 10 to 80 15 to 50

[0021] The aluminosilicate zeolite having a FAU framework may be a single type of FAU zeolite or a mixture of two or more FAU zeolites. The FAU zeolite may be zeolite Y. The FAU zeolite may be two or more Y zeolites having different silica to alumina molar ratios.

[0022] The silicon source and / or aluminum source may further comprise one or more additional components, wherein the one or more additional components are present in amounts such that at least 80% (e.g., at least 90% or at least 95%) of the silicon and / or aluminum is provided by the aluminosilicate zeolite having a FAU framework.

[0023] Aluminum sources other than aluminosilicate FAU zeolites may include hydrated aluminum oxide, aluminum hydroxide, alkali metal aluminates, aluminum alkoxides, water-soluble aluminum salts (eg, aluminum nitrate), and any combination thereof.

[0024] Silicon sources other than aluminosilicate FAU zeolites may include colloidal silica, precipitated silica, fumed silica, alkali metal silicates, tetraalkyl orthosilicates (eg, tetraethyl orthosilicate), and any combination thereof.

[0025] The alkali metal [M] can be lithium, sodium, potassium, rubidium, cesium or any combination thereof. In some aspects, the alkali metal is sodium, potassium or a mixture of sodium and potassium. Examples of suitable alkali metal sources include alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide).

[0026] The structure directing agent [Q] comprises an N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation and / or an N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation represented by the following structures (1) and (2), respectively:

[0027]

[0028] Suitable sources of Q are hydroxides, chlorides, bromides, iodides and / or other salts of the relevant quaternary ammonium compounds.

[0029] The reaction mixture also contains seed crystals from previously synthesized crystalline molecular sieve materials, such as crystalline molecular sieves having an SSY framework (e.g., borosilicate SSZ-60, aluminosilicate SSZ-60). Preferably, in the reaction mixture, the weight ratio of the seed crystals to the silica in the aluminosilicate FAU zeolite is in the range of 0.001:1 to 0.2:1 (e.g., 0.005:1 to 0.15:1 or 0.01:1 to 0.1:1). Adding seed crystals is beneficial to improving the selectivity of SSY and / or shortening the crystallization process.

[0030] The reaction mixture components may be supplied by more than one source. In addition, two or more reaction mixture components may be provided by one source.

[0031] The reaction mixture can be prepared by any conceivable means, wherein mixing is preferably performed by agitation, preferably by stirring means.The reaction mixture can be prepared in batch, continuous or semi-continuous mode.

[0032] The reaction mixture may be in the form of a solution, a colloidal dispersion (colloidal solution), a gel or a paste, with gels being preferred.

[0033] Crystallization and post-synthesis processing

[0034] Crystallization of the molecular sieve from the reaction mixture can be carried out under static or stirring conditions in a suitable reactor vessel such as a polypropylene tank or a Teflon-lined or stainless steel autoclave placed in a convection oven maintained at a temperature of 100° C. to 200° C. for a time sufficient for crystallization to occur (e.g., about 1 day to 21 days or about 1 day to 14 days). In some aspects, crystallization is carried out under static conditions (i.e., in the absence of any particular stirring device during the crystallization process). Preferably, the crystallization process is carried out under autogenous pressure, preferably in an autoclave.

[0035] Once the desired molecular sieve crystals are formed, the solid product can be separated from the reaction mixture by standard mechanical separation techniques (such as centrifugation or filtration). The recovered crystals are washed with water and then dried for a few seconds to a few minutes (e.g., 5 seconds to 10 minutes for rapid drying) or a few hours (e.g., 4 hours to 24 hours for oven drying at 75° C. to 150° C.) to obtain the original molecular sieve crystals after preparation. The drying step can be performed under vacuum or atmospheric pressure.

[0036] As a result of the crystallization process, the recovered as-prepared crystalline molecular sieve product contains within its pore structure at least a portion of the structure directing agent used in the synthesis.

[0037] Some or all of the structure directing agent used during the synthesis of the as-prepared material can be removed by heat treatment (e.g., calcination), ozone treatment or other treatment to form a material that is substantially free of structure directing agents (e.g., greater than 50%, 60%, 70%, 80%, 90%, 95% or 99% free of structure directing agents on a weight basis). Calcination can be performed in any manner conventionally known in the art, for example, the calcination temperature is generally 300° C. to 750° C. (e.g., 400° C. to 600° C.), and the calcination duration is generally 1 hour to 10 hours (e.g., 3 hours to 6 hours). In addition, calcination is generally performed in an oxygen-containing atmosphere such as air or an oxygen atmosphere.

[0038] To the extent desired, any extra-framework alkali metal cations in the prepared molecular sieve as is may be replaced by other cations according to techniques known in the art (e.g., by ion exchange). Preferred replacement cations may include metal ions, hydrogen ions, hydrogen precursors (e.g., ammonium ions), and mixtures thereof. Particularly preferred cations may include cations that regulate the catalytic activity of certain hydrocarbon conversion reactions. These cations may include hydrogen, rare earth metals, and metals of Groups 2 to 15 of the periodic table.

[0039] Characterization of Molecular Sieve

[0040] Aluminosilicate molecular sieves produced according to the methods described herein may have a SiO2 / Al2O3 molar ratio (SAR) in the range of 20 to 200 (e.g., 20 to 150, or 20 to 100, or 20 to 75, or 30 to 200, or 30 to 150, or 30 to 100, or 30 to 75, or 40 to 200, or 40 to 150, or 40 to 100, or 40 to 75). The silica to alumina molar ratio of the molecular sieve may be determined by conventional analysis such as atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), or X-ray fluorescence (XRF).

[0041] Based on the total weight of the composition, the aluminosilicate molecular sieve may contain at least 90 wt%, or at least 95 wt%, or at least 97 wt%, or at least 99 wt% of a pure phase SSY framework, as determined by powder XRD or NMR or by other known methods for such determination. The remainder of the composition is non-SSY material, which may include amorphous material, different crystalline phases, different framework types (e.g., undissolved FAU), or a combination thereof.

[0042] The powder XRD patterns presented herein were determined by standard techniques. The radiation is K-alpha / doublet of copper. Minor changes in the diffraction pattern values ​​may be caused by changes in the organic compounds used in the preparation of the molecular sieve and changes in the molar ratio of the framework material between samples. Calcination may also cause minor changes in the XRD pattern. Despite these minor perturbations, the basic lattice structure remains essentially unchanged.

[0043] Example

[0044] The following illustrative examples are intended to be non-limiting.

[0045] Example 1

[0046] Synthesis of structure-directing agents

[0047] The structure directing agent N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium hydroxide was prepared according to Example 1 of US Pat. No. 6,620,401.

[0048] Example 2

[0049] Synthesis of Borosilicate SSZ-60 (B-SSZ-60)

[0050] Borosilicate SSZ-60 was prepared according to Example 3 of US Patent No. 6,620,401.

[0051] Example 3

[0052] Synthesis of Aluminosilicate SSZ-60 (Al-SSZ-60)

[0053] The following components were added (in order) to a 23 mL Teflon liner: 0.89 g deionized water, 0.27 g aqueous NaOH (50%), 6.87 g OSDA solution (12%) from Example 1, 0.60 g Tosoh 385HUA USY zeolite (SAR=100), and 0.06 g as-synthesized B-SSZ-60 seeds from Example 2. The final molar ratio of the gel was as follows: 1 SiO2 / 0.01 Al2O3 / 0.35 NaOH / 0.35 OSDA / 40H2O / 0.1 B-SSZ-60 seeds. The liner was then capped, placed in an autoclave, and heated in a convection oven at 160°C under tumbling conditions (43 rpm) for 7 days. The solids were then isolated by filtration, washed with deionized water, and dried in an oven at 95°C.

[0054] Powder XRD analysis showed that the as-prepared product was pure phase SSZ-60. Figure 1 Powder XRD of the product is shown.

[0055] The as-prepared product had a SiO2 / Al2O3 molar ratio of 58 as determined by elemental analysis by inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

[0056] Example 4

[0057] Example 3 was repeated except that no B-SSZ-60 seeds were added.

[0058] Analysis by powder XRD showed that the product was a phase other than SSZ-60.

[0059] Example 5

[0060] Physical and Chemical Characterization of Al-SSZ-60

[0061] The as-prepared product of Example 3 was calcined in a muffle furnace under air flow, heated to 595°C at a rate of 1°C / min and held at 595°C for 5 hours before allowing the sample to cool to room temperature.

[0062] The calcined material was ion-exchanged into the ammonium form by treating the calcined molecular sieve with 10 mL (per g molecular sieve) of 1N ammonium nitrate solution at 95°C for 2 hours. The solution was cooled, decanted and the same process was repeated twice. The solid was then separated by filtration, washed with deionized water, and dried in an oven at 95°C. The molecular sieve was subsequently converted into the proton form by calcining the molecular sieve from ambient conditions to 500°C at a rate of 1°C / min and maintaining at 500°C for 3 hours, then cooling the sample to room temperature.

[0063] The proton form molecular sieve had a SiO2 / Al2O3 molar ratio of 64 as determined by ICP-AES.

[0064] The analysis of nitrogen physical adsorption data by t-curve method showed that the material had a 0.18 cm 3 / g micropore volume, 0.30cm 3 / g total pore volume and 23.83m 2 / g of external surface area.

[0065] Analysis by temperature-programmed desorption of n-propylamine showed that the molecular sieve had an acid site density of 388 mmol / g.

[0066] Example 6

[0067] Hydrogenation conversion of n-decane

[0068] The calcined Al-SSZ-60 product was impregnated with palladium at a loading of 0.5 wt % using the required amount of Pd(NH3)4(NO3)2 dissolved in deionized water (buffered at pH=10). The exchanged molecular sieves were dried at 85°C overnight and then calcined in air at 482°C for 3 hours. The Pd / Al-SSZ-60 catalyst was then pelletized at 5 kpsi, crushed and sieved to 20-40 mesh.

[0069] For catalytic testing, 0.5 g of Pd / Al-SSZ-60TON catalyst (weight of dehydrated sample determined by thermogravimetric analysis at 600°C) was loaded in the center of a 23-inch long x 1 / 4-inch OD stainless steel reactor tube with alumina powder loaded upstream of the catalyst for preheating the feed (total pressure of 1200 psig; downflow hydrogen rate of 12.5 mL / min when measured at 1 atmosphere and 25°C; and downflow liquid feed rate of 1 mL / h). The catalyst was first reduced in flowing hydrogen at 315°C for 1 hour. Catalytic testing was conducted at temperatures ranging from 400°F to about 610°F. Products were analyzed approximately every 60 minutes by an online capillary gas chromatograph (GC). Raw data from the GC was collected by an automated data collection / processing system, and hydrocarbon conversion was calculated from the raw data. Conversion is defined as the amount of n-decane that reacts to produce other products (including iso-C10), in mol%. The yields are expressed as mol% of products other than n-decane and include the iso-C10 isomer as a yield product. Figure 3 Shown in.

Claims

1. A method for synthesizing an aluminosilicate molecular sieve having an SSY framework, the method comprising: (1) preparing a reaction mixture, the reaction mixture comprising: (a) an aluminum source and a silicon source, wherein both the aluminum source and the silicon source are aluminosilicate zeolites having a FAU framework; (b) a structure directing agent [Q], the structure directing agent comprising an N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cation and / or an N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cation; (c) an alkali metal [M] source; (d) a hydroxide ion source; (e) seed crystals; and (f) water; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the aluminosilicate molecular sieve.

2. The method of claim 1, wherein the reaction mixture has the following composition in molar ratio:

3. The method of claim 1, wherein the reaction mixture has the following composition in molar ratio:

4. The method of claim 1, wherein the aluminosilicate zeolite having the FAU framework is zeolite Y.

5. The method of claim 1, wherein the alkali metal comprises sodium, potassium, or a mixture of sodium and potassium.

6. The method of claim 1, wherein the seed crystals comprise a crystalline molecular sieve having an SSY framework.

7. The method of claim 1, wherein: In the reaction mixture, a weight ratio of the seed crystals to silica in the aluminosilicate zeolite having the FAU framework is in a range of 0.001:1 to 0.2:

1.

8. The method of claim 1, wherein the crystallization conditions comprise heating the reaction mixture at a temperature of 100°C to 200°C under autogenous pressure.

9. An aluminosilicate molecular sieve having an SSY framework and having N-ethyl-N-(3,3,5-trimethylcyclohexyl)pyrrolidinium cations and / or N-ethyl-N-(2,4,4-trimethylcyclopentyl)pyrrolidinium cations within its pore structure in its as-prepared form.

10. The aluminosilicate molecular sieve of claim 9, wherein the aluminosilicate molecular sieve has a SiO2 / Al2O3 molar ratio in the range of 20 to 200.

11. The aluminosilicate molecular sieve of claim 9, wherein the aluminosilicate molecular sieve has a SiO2 / Al2O3 molar ratio in the range of 30 to 100.

12. The aluminosilicate molecular sieve of claim 9, wherein the aluminosilicate molecular sieve has a phase purity of at least 95 wt%.

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