Small crystal SSZ-41, its synthesis and uses

Abstract

A method for producing small crystal, high aluminum content zincoaluminosilicate crystalline materials having an SSZ-41 framework structure is disclosed. Compositions produced according to the method and uses thereof are also disclosed.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 160,979, filed March 15, 2021, the disclosure of which is incorporated herein by reference.

[0002] Field This disclosure relates to small crystal size SSZ-41 molecular sieves, their synthesis, and use as adsorbents and catalysts for organic conversion reactions. [Background technology]

[0003] Molecular sieves are a commercially important class of materials with specific chemical compositions and unique crystalline structures with distinct pore structures revealed by distinctive X-ray diffraction (XRD) patterns. The crystalline structure defines the cavities and pores characteristic of a particular type of molecular sieve.

[0004] A conventional preparation method using crystalline molecular sieve SSZ-41 and α,ω-di(N-methylpiperidine) polymethylene dicationic compound and α,ω-di(1,4-diazabicyclo[2.2.2]octane) polymethylene dicarboxylic acid compound as structure directing agents is taught in U.S. Pat. No. 5,591,421.

[0005] SSZ-41 materials are useful as catalysts in a variety of organic transformations In such applications, activity and / or selectivity are generally found to be improved when the molecular sieve product has a low silica-to-alumina molar ratio and small crystal size. Unfortunately, aluminum can be a crystallization inhibitor for some zeolites, including SSZ-41 materials, making it difficult to produce low silica-to-alumina molar ratios in most existing synthetic routes without significantly producing impurity phases, particularly MTW framework-type materials.

[0006] In accordance with the present disclosure, it has been discovered that SSZ-41 can be produced at higher aluminum concentrations than previously exemplified. Furthermore, it has been discovered that products composed of small crystal aggregates of SSZ-41 with low silica-to-alumina molar ratios have improved activity and selectivity as isomerization catalysts compared to catalysts prepared from conventional SSZ-41. Summary of the Invention

[0007] In a first aspect, there is provided a zincoaluminosilicate molecular sieve having a framework structure of SSZ-41 and an average crystallite size of 500 nm or less.

[0008] In a second aspect, a method for synthesizing a zincoaluminosilicate molecular sieve having an SSZ-41 framework structure is provided, comprising: (1) forming a reaction mixture comprising (a) an FAU framework-type zeolite, (b) a zinc source, (c) a structure directing agent (Q) comprising 1,1'-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication, (d) a lithium source, (e) a hydroxide ion source, (f) water, and (g) seeds; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form zincoaluminosilicate molecular sieve crystals, wherein the reaction mixture is sodium-free or substantially sodium-free.

[0009] In a third aspect, there is provided a process for converting a feedstock comprising organic compounds to conversion products, the process comprising: (i) contacting the feedstock with a catalyst comprising a zincoaluminosilicate molecular sieve having an SSZ-41 framework structure and an average crystal size of 500 nm or less under organic compound conversion conditions to produce an effluent comprising the conversion products; and (ii) recovering the converted products from the effluent. The following is further disclosed in relation to the present invention. [1] Zincoaluminosilicate molecular sieve with SSZ-41 framework structure and average crystal size of 500 nm or less. [2] SiO in the range of 30 to less than 100 2 / Al 2 O 3 Molar ratio and SiO in the range of 15 to 75 2 [1] The zincoaluminosilicate molecular sieve according to [1], having a molar ratio of ZnO to ZnO. [3] The zincoaluminosilicate molecular sieve according to [1], wherein the average crystal size is in the range of 50 nm to 500 nm. [4] 1. The zincoaluminosilicate molecular sieve according to [1], having a phase purity of at least 95% by weight. [5] The zincoaluminosilicate molecular sieve according to [1], further comprising 1,1'-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication in its pores. [6] 1. A method for synthesizing a zincoaluminosilicate molecular sieve having an SSZ-41 framework structure, said method comprising: (1) forming a reaction mixture, the reaction mixture comprising: (a) FAU framework zeolite, (b) a zinc source; (c) a structure-directing agent (Q) containing 1,1'-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication; (d) a lithium source; (e) a hydroxide ion source; (f) water, and (g) forming the reaction mixture including a seed; (2) subjecting said reaction mixture to crystallization conditions sufficient to form crystals of said zincoaluminosilicate molecular sieve; wherein the reaction mixture is sodium-free or substantially sodium-free. [7] The method according to [6], wherein the reaction mixture has the following composition in molar ratio: Table 1A [8] The method according to [6], wherein the reaction mixture has the following composition in molar ratio: Table 1B [9] The method according to [6], wherein the FAU framework zeolite is zeolite Y.

[10] [6] The method of [6], wherein the zinc source comprises a zinc salt of an organic or inorganic acid, a zinc-exchanged FAU framework zeolite, or any combination thereof.

[11] [6] The method of [6], wherein the lithium source comprises lithium hydroxide, lithium halide, or any combination thereof.

[12] The method of claim 6, wherein the seeds comprise a molecular sieve having a framework structure of SSZ-41.

[13] The reaction mixture is 2 The method according to [6], wherein the seed content is 0.1 to 20 wt.% based on the total weight of the mixture.

[14] The method according to [6], wherein the crystallization conditions include heating the reaction mixture under autogenous pressure at a temperature in the range of 100°C to 200°C for a time period of 1 to 14 days.

[15] 1. A process for converting a feedstock comprising organic compounds into a conversion product, the process comprising: (i) contacting the feedstock with a catalyst comprising a zincoaluminosilicate molecular sieve having a framework structure of SSZ-41 and an average crystal size of 500 nm or less under conditions for converting organic compounds to produce an effluent comprising a conversion product; (ii) recovering said conversion products from said effluent.

[16] The zincoaluminosilicate molecular weight is in the range of 30 to less than 100 SiO 2 / Al 2 O 3 Molar ratio and SiO in the range of 15 to 75 2

[15] , having a molar ratio of ZnO to ZnO.

[17]

[15] The process according to

[15] , wherein the zincoaluminosilicate molecular sieve has an average crystal size in the range of 50 nm to 500 nm.

[18]

[15] The process of

[15] , wherein the zincoaluminosilicate molecular sieve has a phase purity of at least 95 wt%. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows the powder X-ray diffraction (XRD) pattern of the as-synthesized product of Example 1.

[0011] [Figure 2] A and B show scanning electron micrograph (SEM) images of conventional SSZ-41 (large particle SSZ-41) and the as-synthesized SSZ-41x product of Example 1.

[0012] [Figure 3] 1 is a plot of conversion or yield versus temperature for n-decane conversion over a Pd / SSZ-41x catalyst.

[0013] [Figure 4] 1 is a plot of product yield versus conversion for n-decane conversion over a Pd / SSZ-41x catalyst.

[0014] [Figure 5] 1 is a plot of methylnonane isomer distribution versus conversion for n-decane conversion over a Pd / SSZ-41x catalyst. DETAILED DESCRIPTION OF THE INVENTION

[0015] definition As used herein, the term "zeolite" refers to an aluminosilicate molecular sieve having a framework composed of alumina and silica (ie, repeating tetrahedral units of SiO4 and AlO4).

[0016] The term "zincoaluminosilicate" refers to a molecular sieve having a framework composed of zinc, alumina, and silica (ie, repeating ZnO4, AlO4, and SiO4 tetrahedral units).

[0017] As used herein, the term "framework type" has the meaning set forth in "Atlas of Zeolite Framework Types" by Ch. Baerlocher, L.B. McCusker and D.H. Olson (Elsevier, 6th revised edition, 2007).

[0018] The term "as synthesized" refers to the molecular sieve in its state after crystallization and before removal of the structure directing agent.

[0019] The term "SiO2 / Al2O3 molar ratio" is sometimes abbreviated as "SAR."

[0020] The term "SSZ-41x" refers to a zincoaluminosilicate molecular sieve having the structure of SSZ-41 and characterized by an average crystallite size of 500 nm or less.

[0021] Molecular sieve synthesis A zincoaluminosilicate molecular sieve having an SSZ-41 framework structure can be synthesized by (1) forming a reaction mixture containing (a) an FAU framework zeolite, (b) a zinc source, (c) a structure directing agent (Q) comprising 1,1'-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication, (d) a lithium source, (e) a hydroxide ion source, (f) water, and (g) seeds; and (2) subjecting the reaction mixture to crystallization conditions sufficient to form zincoaluminosilicate molecular sieve crystals, wherein the reaction mixture is sodium-free or substantially sodium-free.

[0022] The reaction mixture may have a composition, in molar ratio, within the ranges set forth in Table 1. [Table 1] wherein Q comprises 1,1′-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication.

[0023] The FAU framework-type zeolite can be zeolite Y. The FAU framework-type zeolite can be an ammonium-form zeolite or a hydrogen-form zeolite (e.g., NH4 + - Forms of zeolite Y and H +The FAU framework-type zeolite may have a SiO2 / Al2O3 molar ratio of at least 12 (e.g., 12 to 500, or 12 to 100, or 30 to 500, or 30 to 100, or 60 to 80). The FAU framework-type zeolite may comprise two or more zeolites. Typically, the two or more zeolites are zeolite Y having different silica-to-alumina molar ratios. Examples of suitable aluminosilicate zeolites include Y zeolites CBV720, CBV760, and CBV780 available from Zeolyst International, and Y zeolites HSZ-HUA385 and HSZ-HUA390 available from Tosoh. The FAU framework-type zeolite may be used as the sole or primary source of silicon and aluminum in the reaction mixture.

[0024] The FAU framework-type zeolite can be a zinc-exchanged zeolite (e.g., zinc-exchanged zeolite Y), where the zeolite can also be the source of zinc metal in the reaction mixture. "Zinc-exchanged zeolite" refers to an aluminosilicate zeolite in which zinc metal is disposed on the surface and / or within the cages and / or pores of the aluminosilicate zeolite. It does not refer to an aluminosilicate in which the zinc metal is within the aluminosilicate framework.

[0025] Additionally or alternatively, the zinc source may be a zinc salt of an organic or inorganic acid. Exemplary zinc salts include zinc formate, zinc acetate, zinc citrate, zinc chloride, zinc bromide, zinc nitrate, and zinc sulfate.

[0026] Sources of lithium include lithium hydroxide and other lithium salts, especially lithium halides such as lithium chloride.

[0027] Preferably, the reaction mixture is sodium-free or substantially sodium-free. The term "substantially free" means that the indicated substance is not intentionally added to the composition, or preferably is not present at analytically detectable levels. This includes compositions in which the specified substance is present only as an impurity of one of the intentionally added substances. For example, a "substantially sodium-free" composition may refer to a composition containing 0.005% or less, 0.002% or less, and / or 0.001% or less sodium by weight. Applicants have discovered that the presence of sodium can cause various impurities in the final product. For example, if SSZ-41 is synthesized in the presence of sodium cations, ZSM-12(MTW) ​​can be an impurity in the final product.

[0028] The hydroxide ion source can be lithium hydroxide. The structure directing agent can also be used to provide hydroxide ions.

[0029] The structure directing agent (Q) comprises 1,1′-(1,4-butanediyl)bis-4-aza-1-azoniabicyclo[2.2.2]octane dication (DABCO-diquat-4) of the following structure (1): [ka]

[0030] Suitable sources of Q are hydroxides, chlorides, bromides, and / or other salts of diquaternary ammonium compounds.

[0031] The reaction mixture also contains seeds, typically SSZ-41 from a previous synthesis, desirably in an amount of 0.1 to 20 wt. % (e.g., 0.5 to 10 wt. %) based on the total weight of SiO2 in the reaction mixture. Seeding can be advantageous in improving the selectivity of SSZ-41x and / or shortening the crystallization process.

[0032] The components of the reaction mixture can be provided from multiple sources, or two or more reaction components can be provided by a single source. The reaction mixture can be prepared either batchwise or continuously.

[0033] Crystallization of the desired molecular sieve from the above reaction mixture can be carried out in a suitable reaction vessel, such as a polypropylene jar or Teflon-lined or stainless steel autoclave, at a temperature of 100°C to 200°C (e.g., 130°C to 180°C) for a time sufficient for crystallization to occur at the operating temperature, such as about 1 day to 14 days (e.g., 3 days to 10 days), under either static, tumbling, or stirred conditions. Crystallization is typically carried out under pressure in an autoclave so that the reaction mixture is subjected to autogenous pressure.

[0034] 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 dried for a few seconds to a few minutes (e.g., 5 seconds to 10 minutes for flash drying) or for several hours (e.g., 4 hours to 24 hours for oven drying at 75°C to 150°C) to obtain the as-synthesized molecular sieve crystals. The drying step can be carried out under vacuum or atmospheric pressure.

[0035] As a result of the crystallization process, the recovered crystalline molecular sieve product contains within its pores at least a portion of the structure directing agent used in its synthesis.

[0036] The as-synthesized molecular sieve can be subjected to heat treatment, ozone treatment, or other treatment to remove some or all of the directing agent used in its synthesis. Removal of the directing agent can be accomplished using a heat treatment (e.g., calcination) in which the as-synthesized material is heated in an atmosphere selected from air, nitrogen, or a mixture thereof at a temperature sufficient to remove some or all of the directing agent. For convenience, atmospheric pressure is required for the heat treatment, although subatmospheric pressures can also be used. The heat treatment can be performed at a temperature of at least 370°C (e.g., 400-700°C) for at least 1 minute, typically for up to 20 hours (e.g., 1-8 hours).

[0037] To the extent desired, any extraframework metal cations (e.g., Li+) in the molecular sieve can be replaced by ion exchange with other cations according to techniques well known in the art. Replacement cations include metal ions, hydrogen ions, hydrogen precursors (e.g., ammonium ions), and mixtures thereof.

[0038] Molecular sieve characterization In its as-synthesized and anhydrous form, the SSZ-41x molecular sieve can have a chemical composition, in molar ratios, within the ranges shown in Table 2. [Table 2] wherein Q comprises 1,1′-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication.

[0039] The crystals of the SSZ-41x molecular sieve can have an average crystal size of 500 nm or less. Typically, the crystals can have an average crystal size in the range of 50 to 500 nm (e.g., 50 to 250 nm, or 75 to 500 nm, or 75 to 250 nm). Conventional SSZ-41 usually has an average crystal size of at least 1 micron.

[0040] Crystal size is based on individual crystals (including twins) but does not include crystal agglomerations. Crystal size is the length of the longest diagonal of a three-dimensional crystal. Direct measurement of crystal size can be performed using microscopy techniques such as scanning electron microscope (SEM) and transmission electron microscope (TEM). For example, SEM measurements involve examining the morphology of a material at high magnification (typically 1000x to 10,000x). SEM can be performed by distributing a representative portion of molecular sieve powder on a suitable mount so that individual particles are reasonably evenly spread across the entire field of view at 1000x to 10,000x magnification. From this population, a statistically significant sample (e.g., 50-200) of random individual crystals is examined, and the longest diagonal of each individual crystal is measured and recorded. (Particles that are clearly large polycrystalline aggregates should not be included in the measurement.) Based on these measurements, the arithmetic mean of the sample crystal size is calculated.

[0041] As conventionally synthesized, for example, as taught by U.S. Pat. No. 5,591,421, molecular sieve SSZ-41 has a powder X-ray diffraction (XRD) pattern that includes at least the peaks listed in Table 3 below for the synthetic form of the molecular sieve, and at least the peaks listed in Table 4 below for the calcined form of the molecular sieve. [Table 3] [Table 4]

[0042] The X-ray diffraction data reported herein were collected by standard techniques using copper K-α radiation. The determination of the parameter 2-θ is subject to both human and mechanical error, which, combined, result in an uncertainty of approximately ±0.10° for each reported value of 2-θ. It is understood that d-spacing values, when converted to corresponding d-spacing values ​​using Bragg's law, have a corresponding deviation determined based on ±0.10° 2-θ. The relative intensity of a line, I / Io, represents the ratio of the peak intensity to the intensity of the most intense line above background. Relative intensities are given by the following symbols: VS = very strong (>60), S = strong (≥40 and ≤60), M = moderate (≥20 and <40), and W = weak (<20).

[0043] It is known that certain lines in the X-ray pattern of molecular sieves tend to broaden as the relevant dimension of the molecular sieve crystal decreases, so that adjacent lines begin to overlap, thereby appearing as only partially resolved peaks or as unresolved broad peaks.

[0044] Applicants have discovered that the novel synthesis methods described herein can produce SSZ-41x molecular sieves with high phase purity, i.e., SSZ-41x molecular sieves with phase purities of 95% to 99% or greater, as determined, for example, by Rietveld XRD analysis. As used herein, the term "phase purity" with respect to a molecular sieve means the amount (e.g., by weight) of a single crystalline phase of the molecular sieve relative to the total weight of all phases (crystalline and amorphous) in the molecular sieve material. Thus, although other crystalline phases may be present in the SSZ-41x molecular sieve, the SSZ-41x molecular sieve comprises at least 95% by weight (e.g., at least 97%, or at least 98%, or at least 99%, or at least 99.9%) SSZ-41x as the predominant crystalline phase, and the weight percentage of SSZ-41x is provided relative to the total weight of the molecular sieve crystalline phases present in the composition. Examples of other crystalline phases that may be present as impurities may include faujasite undissolved (FAU) and / or MTW framework type material.

[0045] Industrial Applicability The SSZ-41x materials described herein can be used as adsorbents or catalysts to facilitate one or more of a wide variety of organic compound conversion processes. Examples of chemical conversion processes that can be effectively catalyzed by the SSZ-41x materials described herein, alone or in combination with one or more other catalytically active substances (including other crystalline catalysts), include those requiring catalysts with acid activity. Examples of organic conversion processes that can be catalyzed by the SSZ-41x materials described herein include cracking, hydrocracking, disproportionation, alkylation, oligomerization, and isomerization.

[0046] As with many catalysts, it may be desirable to combine SSZ-41x materials with other materials that can withstand the temperatures and other conditions used in organic conversion processes. Such materials include active and inactive materials, synthetic or naturally occurring zeolites, and inorganic materials such as clays, silica, and / or metal oxides like alumina. The latter may be naturally occurring or in the form of gelatinous precipitates or gels containing mixtures of silica and metal oxides. The use of materials in combination with SSZ-41 (i.e., combined with or present in the synthesis of new active crystals) tends to alter the conversion and / or selectivity of the catalyst in certain organic conversion processes. Inert materials suitably serve as diluents to control the amount of conversion in a given process so that products can be obtained economically and in an orderly manner without employing other means to control the reaction rate. These materials can be incorporated into natural clays (e.g., bentonite and kaolin) to improve the crush strength of the catalyst under commercial operating conditions. These materials (i.e., clays, oxides, etc.) function as binders for the catalyst. Since it is desirable to prevent the catalyst from breaking down into powder in commercial applications, it is desirable to provide a catalyst with good crush strength. These clay and / or oxide binders are typically used solely to improve the crush strength of the catalyst.

[0047] Natural clays that can be composited with SSZ-41x materials include the montmorillonite and kaolin families, including sub-bentonite, kaolin commonly known as Dixie, McNamee, Georgia, and Florida clays, and others whose primary mineral component is halloysite, kaolinite, dickite, nacrite, or anaxite. Such clays can be used in their original as-mined state or after initial calcination, acid treatment, or chemical modification. Binders useful for composites with SSZ-41x also include inorganic oxides such as silica, zirconia, titania, magnesia, beryllia, alumina, and any combination thereof.

[0048] In addition to the above materials, SSZ-41x can be composited with porous matrix materials such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, and ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia, and silica-magnesia-zirconia.

[0049] The relative proportions of SSZ-41x and inorganic oxide matrix can vary widely, with the SSZ-41x content ranging from 1 to 90 wt % (e.g., 2 to 80 wt %) of the composite. [Example]

[0050] The following illustrative examples are intended to be non-limiting.

[0051] Example 1 A Teflon liner was loaded with 0.036 g of anhydrous LiOH, 0.10 g of zinc acetate dihydrate, 0.44 g of Zeolyst CBV760 Y zeolite (SAR = 60), 0.22 g of Tosoh 390HUA Y zeolite (SAR = 500), as-synthesized SSZ-41 seeds (based on 3% of the other two FAU materials as the silica source), 3 mM DABCO-diquat-4 dihydroxide, and water. The total volume of the SDA solution and additional water was 5.6 g. All of the aluminum in the reaction mixture was provided by the two FAU materials. The liner was then capped, sealed in a 23 mL autoclave, and heated in a convection oven at 150 °C under tumbling conditions (43 rpm) for 6–8 days. The solid was then isolated by centrifugation, washed with deionized water, and dried in an oven at 95 °C.

[0052] Figure 1 shows the powder XRD of the as-synthesized product, consistent with the product being SSZ-41x. The powder XRD pattern of the product shows the characteristic broad features of a material with very small crystallites.

[0053] SEM images of conventional SSZ-41 (large particle SSZ-41) and as-synthesized SSZ-41x products are shown in Figures 2A and 2B, respectively.

[0054] The as-synthesized product had an aluminum content of 1.04 wt.% (SAR=84) as determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES).

[0055] The as-synthesized material was then calcined in air by placing a thin bed of material in a calcination dish and heating in a muffle furnace from room temperature to 120°C at a rate of 1°C / min and holding at 120°C for 2 hours. The temperature was then increased at a rate of 1°C / min to 540°C and held at 540°C for 5 hours. The temperature was again increased at 1°C / min to 595°C and held at 595°C for 5 hours. The material was then cooled to room temperature.

[0056] The calcined material was converted to the ammonium form by heating in an ammonium nitrate solution (typically 1 g NH4NO3 / 1 g zeolite in 10 mL HO at 85°C for at least 3 hours). The material was then filtered. This was repeated twice for a total of three exchanges. Finally, the material was washed with deionized water to a conductivity of less than 100 μS / cm and dried in air at 85°C.

[0057] The acid site density was characterized using n-propylamine temperature programmed desorption (TPD) and found to be 312.64 μmol H+ / g.

[0058] Analysis by nitrogen physisorption revealed a micropore volume of 0.1207 cm 3 / g, the external surface area of ​​the t-plot is 122.04 m 2 / g, BET surface area is 383.05 m 2 / g, total pore volume is 0.933 cm 3 / g.

[0059] Examples 2 to 5 For Examples 2-5, the starting materials outlined in Table 5 below were each loaded into a Teflon liner. Zinc-exchanged CBV760 Y zeolite (SAR=60, Zeolyst) was prepared from hydrogen-form Y zeolite by ion-exchange methods known in the art. The zinc-exchanged material had a zinc content of approximately 3 wt.%. The liner was then capped, sealed in a 23 mL autoclave, and heated in a convection oven at 150°C under tumbling conditions (43 rpm) for 6-8 days. The solid was then separated by centrifugation, washed with deionized water, and dried in an oven at 95°C. The recovered product was characterized by powder XRD. [Table 5]

[0060] Examples 6 to 16 For Examples 6-16, the starting materials outlined in Table 6 below were each loaded into a Teflon liner. The zinc source was zinc acetate dihydrate. The liner was then capped, sealed in a 23 mL autoclave, and heated in a convection oven at 150°C under tumbling conditions (43 rpm) for 6-8 days. The solid was then separated by centrifugation, washed with deionized water, and dried in an oven at 95°C. The recovered product was characterized by powder XRD. [Table 6-1] [Table 6-2]

[0061] Example 17 Constraint Index The constraint index is a test for determining the shape-selective catalytic behavior of zeolites. It compares the reaction rates for the cracking of n-hexane and its isomer, 3-methylpentane, under competitive conditions (see, for example, V. J. Frillette et al., J. Catal. 1981, 67, 218-222).

[0062] Ammonium-exchanged SSZ-41x(NH4 + The catalyst (SSZ-41x) was pelletized at 4-5 kpsi, crushed, and meshed to 20-40°C. Next, 0.47 g of this catalyst (dry weight measured by TGA at 600 °C) was loaded into a 3 / 8-inch stainless steel tube lined with catalytically inactive alundum on both sides of the zeolite bed. The reactor tube was heated using an Applied Test Systems (ATS) furnace. Helium was introduced into the reactor at 23 mL / min and atmospheric pressure. The catalyst was dehydrated at 482 °C for 2 h. The reactor temperature was then reduced to the preselected reaction temperature (e.g., 427 °C in this example). Next, the helium flow rate was adjusted to 9.4 mL / min, and an equimolar mixture of n-hexane and 3-methylpentane was introduced into the reactor at a rate of 0.48 mL / h. The feed was delivered via an ISCO pump. 15 min after feed introduction, online product sampling to a gas chromatograph (GC) was initiated. Constraint index values ​​(including 2-methylpentane) were calculated from the GC data using methods known in the art. Representative results are shown in Table 7. [Table 7]

[0063] The initial conversion with SSZ-41x prepared as described herein is more than double that with conventional SSZ-41. Conventional SSZ-41 prepared according to U.S. Patent No. 5,591,421 showed 26% conversion after 10 minutes.

[0064] Example 18 Catalyst preparation Ammonium-exchanged SSZ-41x(NH4 + The Pd-exchanged zeolite (SSZ-41x) was ion-exchanged in an aqueous palladium nitrate solution with a pH of approximately 10 and a Pd loading of 0.5 wt.%. The Pd-exchanged zeolite was washed with deionized water to a conductivity of less than 50 mS / cm and dried. The zeolite was then calcined in air at 482 °C for 3 hours.

[0065] Example 19 Hydroconversion of n-decane For catalytic testing, the Pd catalyst from Example 18 was pelletized at 4-5 kpsi, crushed, and meshed to 20-40 mm. Next, 0.50 g of this catalyst (dry weight determined by TGA at 600 °C) was loaded into the center of a 23-inch long, 0.375-inch outer diameter stainless steel reactor tube with catalytically inactive alundum on both sides of the zeolite bed. The reactor tube was heated using an Applied Test Systems (ATS) furnace. The catalyst was then heated from room temperature to 232 °C for 120 hours, held at 232 °C for 1 hour, heated from 232 °C to 316 °C for 1 hour, and held at 316 °C for 3.5 hours. It was then pre-treated with downflow hydrogen at a rate of 95 mL / min at atmospheric pressure. It was then cooled to 221 °C. The reactor was then pressurized to 1200 psig with a high hydrogen flow rate.

[0066] The reaction was initiated at 221 °C, 1200 psig, with 0.66 mL / h of n-decane and 8.3 mL / min of H2 downflow. The feed was provided by an ISCO pump. The reaction temperature was increased in steps of 5.6 °C to 282 °C. The products were analyzed approximately every 60 min by online capillary GC. Raw data from the GC was collected by an automated data acquisition / processing system, and hydrocarbon conversion was calculated from the raw data. Conversion is defined as the amount (mol%) of n-decane reacted to produce products other than feed n-decane (i.e., iso-C10 and cracked products). The iso-C10 yield is expressed as the mole percent of feed n-decane converted to iso-C10 products. The yield of cracked products (less than C10) is expressed as the mole percent of feed n-decane converted to cracked products.

[0067] The hydrocarbon conversion results are shown in Figures 3-5. As can be seen, up to about 50% conversion, the product is over 80% isomerized C10, mostly mono-branched C10 isomers. Furthermore, an isomerization maximum is observed at about 260 °C, indicating that the catalyst is highly active.

Claims

1. A zincoaluminosilicate molecular sieve having an SSZ-41 framework structure and an average crystal size of 500 nm or less.

2. SiO in the range of 30 to less than 100 ２ / Al ２ O ３ Molar ratio and SiO in the range of 15 to 75 ２ 2. The zincoaluminosilicate molecular sieve of claim 1 having a molar ratio of ZnO to ZnO.

3. 2. The zincoaluminosilicate molecular sieve of claim 1, wherein the average crystallite size is in the range of 50 nm to 500 nm.

4. 10. The zincoaluminosilicate molecular sieve of claim 1 having a phase purity of at least 95 wt.%.

5. The zincoaluminosilicate molecular sieve of claim 1, further comprising 1,1'-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication within the pores of the zincoaluminosilicate molecular sieve.

6. 1. A method for synthesizing a zincoaluminosilicate molecular sieve having an SSZ-41 framework structure, said method comprising: (1) forming a reaction mixture, the reaction mixture comprising: (a) FAU framework zeolite; (b) a zinc source; (c) a structure-directing agent (Q) containing 1,1′-(1,4-butanediyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane] dication; (d) a lithium source; (e) a hydroxide ion source; (f) water, and (g) forming the reaction mixture including a seed; (2) subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the zincoaluminosilicate molecular sieve; wherein the reaction mixture contains no more than 0.005%, no more than 0.002%, no more than 0.001%, or no sodium by weight; the sufficient crystallization conditions are heating the reaction mixture under autogenous pressure at a temperature in the range of 130°C to 180°C for a time period of 3 to 10 days, either under static, tumbling or stirred conditions; The synthesis method, wherein the reaction mixture has the following composition in molar ratio: Table 1A

7. 7. The method of claim 6, wherein the reaction mixture has the following composition in molar ratios: Table 1B

8. 7. The method of claim 6, wherein the FAU framework zeolite is zeolite Y.

9. 7. The method of claim 6, wherein the zinc source comprises a zinc salt of an organic or inorganic acid, a zinc-exchanged FAU framework zeolite, or any combination thereof.

10. 7. The method of claim 6, wherein the lithium source comprises lithium hydroxide, lithium halide, or any combination thereof.

11. 7. The method of claim 6, wherein the seeds comprise a molecular sieve having a framework structure of SSZ-41.

12. The reaction mixture is ２ 7. The method of claim 6, wherein the amount of the seeds is 0.1 to 20 wt. % based on the total weight of the mixture.

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