Zeolites comprising an mtt framework and their preparation

Abstract

The invention provides zeolites comprising ZSM-23 and methods for making zeolites comprising ZSM-23. One of these zeolites is ZSM-23, while the other zeolite is a hybrid composition comprising an MTT framework and an MFI framework, typically a combination of ZSM-23 and ZSM-5. A method for making a zeolite composition comprising an MTT framework.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 613,169, filed on December 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to zeolites comprising an MTT framework and an MFI framework, and methods for producing these zeolites. Background Technology

[0004] Zeolites have a porous structure and are known for their catalytic properties, and are often included as components in fluid cracking catalysts. MTT-type zeolites, especially ZSM-23, possess unique properties but are generally difficult to prepare, particularly on a commercial manufacturing scale. MTT-type zeolites are sometimes referred to as "one-dimensional" zeolites because they have parallel one-dimensional channels in their structure.

[0005] MTT zeolites (including ZSM-23) are typically synthesized in the presence of an organic template, despite the environmental and health risks associated with such templates. For some zeolites, seed-directed synthesis in the absence of an organic template has been reported, but this is not always the case for zeolites with the desired properties.

[0006] We have been seeking improved methods for preparing MTT zeolite. Summary of the Invention

[0007] This invention provides zeolites comprising an MTT framework. One of these zeolites is ZSM-23, and the others are hybrid compositions comprising an MTT framework and an MFI framework (typically a combination of ZSM-23 and ZSM-5). The hybrid zeolite compositions are more stable than the MTT framework alone. In the method of this invention, an organic template is not required for the formation of the MTT framework or the MTT / MFI hybrid composition. The MTT / MFI hybrid composition consists of an in-situ co-generated MTT framework and an MFI framework (typically a combination of ZSM-23 and ZSM-5).

[0008] One embodiment of the invention is a hybrid composition consisting of an MTT framework and an MFI framework, wherein the MTT framework and the MFI framework are physically and / or chemically inseparable from each other without disturbance, wherein the zeolite composition has a silicon to aluminum molar ratio of about 55:1 or less.

[0009] Another embodiment of the present invention is a method for producing a zeolite composition comprising an MTT framework, the method comprising:

[0010] A) Forming an alcohol-free aqueous zeolite precursor mixture comprising a silicon source, an aluminum source, a sodium source, water, and ZSM-23 seed crystals, wherein the molar ratio of sodium to silicon is in the range of about 0.15:1 to about 0.5:1, and the amount of ZSM-23 seed crystals is about 1 wt% to about 50 wt% relative to the total weight of solids in the aqueous zeolite precursor mixture;

[0011] B) Optionally, the aqueous zeolite precursor mixture is heated at a temperature of about 25°C to about 300°C for about 1 minute to about 200 hours to form a heat-treated precursor; and

[0012] C) Crystallize the aqueous zeolite precursor mixture or the heat-treated precursor by heating it at a temperature of about 60°C to about 300°C for about 1 minute to about 72 hours.

[0013] This method typically produces an MTT backbone (usually ZSM-23) or a hybrid composition consisting of an MTT backbone and an MFI backbone (usually ZSM-23 and ZSM-5).

[0014] These and other embodiments and features of the invention will become more apparent from the following description and the appended claims. Attached Figure Description

[0015] Figure 1 shows electron micrographs of the hybrid MTT / MFI zeolite composition of the present invention from Example 1, obtained by scanning electron microscopy (SEM) at two different magnifications.

[0016] Figure 2 is an X-ray powder diffraction (XRD) pattern of the calcined MTT / MFI hybrid composition of the present invention from Example 1.

[0017] Figure 3 shows the argon adsorption isotherm of the MTT / MFI hybrid compositions of the present invention produced according to the method of the present invention. One composition was produced in Example 1 (A) using 5 wt% ZSM-23 seed crystals, while the other composition was produced in Example 4 (B) using 30 wt% ZSM-23 seed crystals.

[0018] Figure 4 is an X-ray powder diffraction (XRD) pattern of calcined MTT framework zeolite produced by the method of the present invention in Example 9.

[0019] Figure 5 is the argon adsorption isotherm of the MTT framework zeolite produced by the method of the present invention in Example 9.

[0020] The accompanying drawings illustrate embodiments of specific aspects of the invention and are not intended to limit the scope of the invention. Detailed Implementation

[0021] This invention provides several types of zeolite compositions. One type consists of fresh zeolite compositions, which are "synthetic" zeolite compositions. Another type consists of steam-treated zeolite compositions. Yet another type consists of calcined zeolite compositions.

[0022] As used throughout this document, the terms “eutectic,” “hybrid,” and MTT / MFI (or ZSM-23 / ZSM-5) refer to the zeolite compositions of the present invention comprising an MTT framework and an MFI framework (or ZSM-23 and ZSM-5) that are physically and / or chemically inseparable from each other when undisturbed.

[0023] The zeolite compositions of the present invention have an MTT framework component (typically ZSM-23, which has an MTT topology) and an MFI framework component (typically pentasil zeolite, sometimes ZSM-5, which has an MFI topology). These MTT / MFI hybrid zeolite compositions of the present invention have a silicon to aluminum molar ratio of about 55:1 or less, typically about 10:1 to about 55:1, preferably about 20:1 to about 45:1, more preferably about 25:1 to about 45:1, and even more preferably about 25:1 to about 40:1. Compared to physical blends of MTT framework zeolites and MFI framework zeolites, these hybrid or eutectic zeolite compositions of the present invention exhibit improved performance, at least for olefin cracking.

[0024] To the best of our knowledge, there is no non-perturbative method for physically or chemically separating the MTT framework component and the MFI framework component of the hybrid MTT / MFI zeolite composition of the present invention. In other words, when combined in the hybrid composition of the present invention, their respective topologies are considered physically or chemically inseparable without disrupting their topologies. The zeolite composition of the present invention cannot be formed by physically mixing pre-formed MTT framework zeolite and pre-formed MFI framework zeolite. Figure 1 shows SEM images of the MTT / MFI hybrid composition of the present invention, illustrating the crystallinity of the composition at two different magnifications.

[0025] The novel hybrid MTT / MFI zeolite composition of the present invention has a powder X-ray diffraction (XRD) pattern that can be interpreted as a hybrid or eutectic comprising an MTT framework and an MFI framework (typically ZSM-23 and ZSM-5). In the XRD pattern of the hybrid MTT / MFI zeolite composition, the ratio of peak intensity at approximately 7.8° to approximately 7.95° 2θ to peak intensity at approximately 19.5° to approximately 19.8° 2θ is typically approximately 7.0 to approximately 7.8; this is visible in the XRD pattern shown in Figure 2. The XRD pattern suggests that the MTT component of the hybrid composition is typically approximately 25% to approximately 95%, often approximately 30% to approximately 85%, with the remainder being the MFI component. The hybrid composition typically has a diameter of approximately 100 μm. 2 / g or greater, preferably about 120 m 2 / g or greater surface area. The micropore volume in the hybrid composition is typically about 0.05 cm³. 3 / g or greater, preferably about 0.075 cm 3 / g or larger.

[0026] In some embodiments, the MTT / MFI hybrid composition has about 25% to about 95% MTT, preferably about 30% to about 85% MTT, with the remainder being MFI, and has about 100 μm 2 / g or greater surface area and / or approximately 0.05 cm² 3 / g or larger micropore volume. In other embodiments, the MTT / MFI hybrid composition has about 30% to about 85% MTT, the remainder being MFI, and has about 120 μm 2 / g or greater surface area and approximately 0.05 cm² 3 / g or greater, preferably about 0.075 cm 3 / g or greater micropore volume. More preferably, the MTT component is ZSM-23 and the MFI component is pentasil zeolite, preferably ZSM-5.

[0027] Another feature of the MTT / MFI hybrid compositions of the present invention is shown in the argon adsorption isotherms of Figure 3, where A is an MTT / MFI hybrid composition produced using 5 wt% ZSM-23 seed crystals, and B is an MTT / MFI hybrid composition produced using 30 wt% ZSM-23 seed crystals. Although composition A in Figure 3 indicates structural irregularities at a P / P0 of approximately 0.4, the argon adsorption isotherms of both MTT / MFI hybrid compositions show no structural defects, such as micropore blockage (sometimes referred to as closure behavior).

[0028] The MTT / MFI hybrid composition of the present invention can be prepared using the method of the present invention. The method of the present invention can also produce MTT framework zeolites, particularly ZSM-23.

[0029] In the method of the present invention, some of the steps can be considered to be carried out under hydrothermal conditions, since one or more steps involve heating in the presence of water (sometimes in the form of steam).

[0030] The method of this invention utilizes an aqueous zeolite precursor mixture, which consists of water, a silicon source, an aluminum source, a sodium source, and ZSM-23 seed crystals. The aqueous zeolite precursor mixture typically has a pH in the range of about 9 to about 11. In some cases, it may be necessary to add an acid or base to achieve the desired pH value.

[0031] The amounts of aluminum and silicon sources present in the aqueous zeolite precursor mixture depend on the desired molar ratio of silicon to aluminum in the resulting zeolite composition. Typical silicon to aluminum molar ratios are from about 10:1 to about 55:1, preferably from about 20:1 to about 45:1, more preferably from about 25:1 to about 45:1, and even more preferably from about 25:1 to about 40:1 when forming an MTT / MFI hybrid composition.

[0032] The molar ratio of sodium to silicon is typically in the range of about 0.15:1 to about 0.5:1, preferably about 0.15:1 to about 0.45:1, more preferably about 0.2:1 to about 0.4:1, and even more preferably about 0.2:1 to about 0.35:1. For these molar ratios, when determining the molar ratio of sodium to silicon, all sodium sources are included, including silicon and / or aluminum sources, sodium sources, and alkalis.

[0033] Suitable silicon sources include sodium silicate, sodium metasilicate, stabilized silica sol, silica gel, polysilicic acid, tetraethyl orthosilicate (TEOS), fumed silica, precipitated silica, and any combination of two or more of the foregoing.

[0034] Suitable aluminum sources include aluminum salts such as Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, and Al(H2PO4)3, as well as water-insoluble aluminum compounds such as alumina and aluminum trihydrate (Al(OH)3) such as gibbsite and bauxite concentrate, heat-treated aluminum trihydrate such as rapidly calcined aluminum trihydrate, boehmite, pseudoboehmite, hydrated aluminum chloride, hydrated aluminum nitrohydrol, sodium aluminate, and combinations of any two or more of the foregoing. Preferred aluminum sources include aluminum sulfate.

[0035] When the silicon or aluminum source is a sodium compound, typically a sodium salt, the sodium source can be either a silicon or aluminum source. When the sodium source is neither a silicon nor an aluminum source, suitable sodium sources include sodium hydroxide, sodium oxide, sodium chloride, sodium bromide, sodium carbonate, sodium bicarbonate, sodium amide, and combinations of any two or more of the foregoing. One or more sodium-containing aluminum sources and / or one or more sodium-containing silicon sources combined with one or more sodium sources can be used. When using a combination of sodium sources, the combination preferably includes a sodium-containing silicon source and a sodium source, such as sodium silicate and sodium hydroxide.

[0036] When using an acid, an inorganic acid is preferred. Suitable inorganic acids include sulfuric acid, phosphoric acid, nitric acid, boric acid, hydrochloric acid, and hydrobromic acid. Other acids, including organic acids, may be used if necessary.

[0037] When using an alkali, an inorganic alkali is preferred. Suitable inorganic alkalis include lithium hydroxide, sodium hydroxide, sodium oxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, aluminum hydroxide, gallium hydroxide, indium hydroxide, and any combination of two or more of the foregoing. Other alkalis may be used.

[0038] Water is typically used in an amount that achieves the desired concentration and / or molar ratio of water to silicon in the aqueous zeolite precursor mixture. The water in the molar ratio includes water introduced into the aqueous zeolite precursor mixture along with other components such as a silicon source. The molar ratio of water to silicon is typically from 1:1 to about 50:1, preferably in the range of about 2:1 to about 35:1, more preferably in the range of about 5:1 to about 30:1, and even more preferably in the range of about 7:1 to about 25:1.

[0039] ZSM-23 seed crystals are typically used in an amount of about 1 to about 50 wt%, preferably about 2 wt% to about 45 wt%, more preferably about 4 wt% to about 40 wt%, and even more preferably about 5 wt% to about 35 wt%, relative to the total weight of the solid components of the aqueous zeolite precursor mixture.

[0040] MTT framework compositions and hybrid zeolite compositions comprising MTT and MFI frameworks can be produced according to the present invention by combining silicon-containing components, aluminum-containing components, sodium-containing components, water, and ZSM-23 seed crystals.

[0041] In some embodiments, the molar ratio of silicon to aluminum is from about 10:1 to about 250:1; the ratio of sodium to silicon is from about 0.15:1 to about 0.45:1; the ratio of water to silicon is from about 1:1 to about 50:1; and / or about 2 wt% to about 45 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0042] In a preferred embodiment, the molar ratio of silicon to aluminum is from about 10:1 to about 250:1; the ratio of sodium to silicon is from about 0.15:1 to about 0.45:1; the ratio of water to silicon is from about 1:1 to about 50:1; and about 2 wt% to about 45 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0043] In other embodiments, the molar ratio of silicon to aluminum is from about 25:1 to about 150:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.4:1; the ratio of water to silicon is from about 2:1 to about 35:1; and / or about 4 wt% to about 40 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0044] In a preferred embodiment, the molar ratio of silicon to aluminum is from about 25:1 to about 150:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.4:1; the ratio of water to silicon is from about 2:1 to about 35:1; and about 4 wt% to about 40 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0045] In other embodiments, the molar ratio of silicon to aluminum is from about 20:1 to about 100:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.35:1; the ratio of water to silicon is from about 5:1 to about 30:1; and / or about 5 wt% to about 35 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0046] In a preferred embodiment, the molar ratio of silicon to aluminum is from about 20:1 to about 100:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.35:1; the ratio of water to silicon is from about 5:1 to about 30:1; and about 5 wt% to about 35 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0047] To form an aqueous zeolite precursor mixture, a silicon source, an aluminum source, a sodium source, water, and ZSM-23 seed crystals are combined. This combination can be accomplished by any of the methods known in the art for preparing aqueous zeolite precursor mixtures. These components can be combined in any order; preferably, the ZSM-23 seed crystals are the last component combined. The aqueous zeolite precursor mixture typically contains about 25 wt% or less solids relative to the total weight of the mixture, but more or less solids can be used as needed.

[0048] In the method of the present invention, a crystallization step can be performed once the aqueous zeolite precursor mixture is formed. In some embodiments, an optional heating step is performed prior to the crystallization step. Because the method of the present invention can be performed with or without the optional heating step, the method steps include a) crystallizing the aqueous zeolite precursor mixture, or b) heating and then crystallizing.

[0049] Although an occasional amount of alcohol (e.g., less than 1 wt%) may be present in the aqueous zeolite precursor mixture, the aqueous zeolite precursor mixture is alcohol-free, i.e., no alcohol is added to the mixture or is part of the mixture. When the optional heating step is performed, no alcohol is introduced before or after the optional heating step, thus making the method of the present invention considered alcohol-free.

[0050] The crystallization process can begin immediately after the formation of the aqueous zeolite precursor mixture. In some embodiments, prior to the crystallization step, the aqueous zeolite precursor mixture is stirred at ambient temperature for a period of time (without heating), typically one minute or longer, typically from about one minute to about one or two hours, preferably from about one minute to about thirty minutes. In other embodiments, it is preferable to subject the aqueous zeolite precursor mixture to an optional heating step prior to the crystallization step.

[0051] In an optional heating step, the aqueous zeolite precursor mixture is heated to one or more temperatures within the range of about 25°C to about 300°C, preferably about 40°C to about 230°C, more preferably about 50°C to about 175°C, and even more preferably about 75°C to about 150°C. This optional heating step is typically carried out under autogenous pressure in a sealed container with or without stirring, preferably with stirring. The duration of the heating step is typically from about 1 minute to about 200 hours, preferably from about 15 minutes to about 48 hours, more preferably from about 1 hour to about 36 hours. The heating step can be carried out in a vessel, process piping, heat exchanger, or other process equipment.

[0052] As used throughout this document, the phrase "heat-treated precursor" refers to the substance obtained at the end of an optional heating step. In some cases, the heat-treated precursor appears as a gel, and in others as a slurry, and in still others as a paste. When the water content in the heat-treated precursor is very low, the heat-treated precursor may have a powdery appearance.

[0053] In the crystallization step, the aqueous zeolite precursor mixture or the heat-treated precursor is heated at one or more temperatures ranging from about 60°C to about 300°C, preferably from about 100°C to 250°C, more preferably from about 150°C to about 200°C. The crystallization step is carried out for about 1 minute to about 72 hours, preferably from about 15 minutes to about 36 hours, more preferably from about 30 minutes to about 30 hours, and even more preferably from about 1 hour to about 24 hours. The crystallization step is sometimes carried out in a sealed container under autogenous pressure. Crystallization can be carried out with or without stirring, preferably with stirring. In some crystallization steps, the removed water is in the form of steam and is preferably discharged from the reactor or reaction zone where crystallization is carried out, preferably periodically.

[0054] As is known in the art, products produced by zeolite preparation methods may differ from the desired product. In the methods of the present invention, an amorphous phase is sometimes formed in the MTT / MFI eutectic zeolite composition. Under a given set of process conditions, an amorphous phase is obtained in the product when the crystallization time is too short and / or the crystallization temperature is too low. Within a given set of process parameters, the crystallization time and temperature to avoid the formation of an amorphous phase can be determined. Similarly, the methods of the present invention sometimes form an MFI framework instead of an MTT / MFI eutectic zeolite composition. Under a given set of process conditions, when the crystallization time is too long, an MFI framework zeolite is obtained as the product. Within a given set of process parameters, the crystallization time to minimize or avoid the formation of a product containing an MFI framework but without MTT framework components can be determined.

[0055] In some cases, the method of the present invention sometimes forms MTT framework zeolite instead of an MTT / MFI eutectic zeolite composition. Under a given set of process conditions, one or more of the process parameters can be varied to determine whether an MTT framework zeolite or an MTT / MFI eutectic zeolite composition is formed, and therefore the process parameters of the present invention can be adjusted as needed to form an MTT framework zeolite or an MTT / MFI eutectic zeolite composition.

[0056] In the XRD pattern of the MTT framework zeolite formed by the method of the present invention, the ratio of the peak intensity at about 7.8° to about 7.95° 2θ to the peak intensity at about 19.5° to about 19.8° 2θ is typically about 0.92 to about 1.1; this can be seen in the XRD pattern shown in Figure 4.

[0057] Another characteristic of the MTT framework zeolite formed by the method of the present invention is shown in the argon adsorption isotherm in Figure 5. Although there is an indication of structural irregularity at a P / P0 slightly above about 0.4, the argon adsorption isotherm curve of the MTT framework zeolite shows that there are no structural defects, such as micropore blockage.

[0058] The zeolite composition of the present invention can be used in catalysts for cracking hydrocarbon feedstocks (such as feedstocks consisting of gaseous olefins or mixtures of gaseous olefins) at one or more elevated temperatures.

[0059] Olefin cracking can represent more complex catalytic cracking processes, such as fluidized catalytic cracking (FCC) in refining applications. FCC catalysts and FCC additives incorporating ZSM-5 materials have been well established for use in FCC units to convert gasoline-range components (particularly gasoline-range olefins) into lighter olefins, such as propylene and / or butene and / or ethylene. Similarly, the zeolite compositions of the present invention exhibit improved olefin cracking compared to typical ZSM-5 materials, and are therefore suitable as components in FCC catalysts and / or FCC additives to improve light olefin yields during fluidized catalytic cracking, when used as a substitute for or in addition to more conventional zeolites such as ZSM-5.

[0060] In typical olefin cracking processes, gaseous olefins or mixtures of gaseous olefins (optionally with an inert gas, typically a combination of helium, nitrogen, and / or argon) are contacted with the MTT / MFI eutectic zeolite composition of the present invention at one or more elevated temperatures (typically from about 200°C to about 650°C, preferably from about 300°C to about 550°C). The olefins typically have four to about eight carbon atoms; preferably, olefins having six carbon atoms, particularly 1-hexene. Some MTT / MFI hybrid zeolite compositions (especially ZSM-23 / ZSM-5 hybrid zeolite compositions) produced in the practice of the present invention exhibit improved olefin yields, particularly propylene and / or butene and ethylene yields. The MTT / MFI eutectic zeolite compositions of the present invention possess the same characteristics and preferences described above in olefin cracking processes.

[0061] Furthermore, the zeolite compositions of the present invention can be used to improve the performance of adsorbents, alkylation catalysts, isomerization catalysts, oligomerization catalysts, catalysts for cracking feedstocks containing bio-based or waste plastics, and catalysts for methanol-to-olefins, methanol-to-gasoline, and methanol-to-jet fuel processes and technologies (including alcohol dehydration).

[0062] The following examples are provided for illustrative purposes and are not intended to limit the scope of the invention.

[0063] Example

[0064] To characterize the zeolites in the embodiments and the appendix, one or more of the following characterization methods were used.

[0065] Specific surface areaMore specifically, the Brunauer-Emmett-Teller specific surface area (BET) was determined by argon adsorption at 87 K.

[0066] Mesopore surface area (MeSA) was determined using the t-plot method based on data generated from argon adsorption at 87 K.

[0067] The micropore volume was determined by nonlocal density functional theory (NLDFT or DFT) calculations based on examples from measured argon adsorption isotherms in the following literature, including Thommes, M., "Textural Characterization of Zeolites and Ordered Mesoporous Materials by Physical Adsorption," in Stud. Surf. Sci. Catal., vol. 168, and J. Cejka et al., Oxford, UK: Elsevier BV, 2007, 495-524.

[0068] In the table below, PV is an abbreviation for pore volume; MiPV and μPV are abbreviations for micropore volume.

[0069] Powder X-ray diffraction (XRD). X-ray powder diffraction analysis was performed on a D8 ADVANCE powder diffractometer (Bruker Inc.) using a CuKα anode as the X-ray source (λ=1.54060 Å).

[0070] Catalytic results The catalytic conversion and product yield were determined using an online gas chromatograph (GC; Agilent 6890) equipped with an FID detector, to obtain the catalytic conversion and product yield based on weight % carbon. The conversion was calculated by subtracting the total GC area of ​​the remaining C6 olefins (C6 = isomerized products) in the product from the feed hexene and dividing by the feed hexene.

[0071] Conversion rate (%) = (C 6= Feed - C 6= Product) / (C 6= Feed) x 100

[0072] Relative product yield is calculated by dividing the GC area of ​​a specific product by the total area. Product selectivity is calculated by dividing the product yield by the conversion rate. The hydrogen transfer index (HTI) is the ratio of isobutane to the total number of C4 hydrocarbons present (isobutane, n-butane, isobutene, n-butene, and butadiene).

[0073] Example 1

[0074] In a flask, water glass (sodium silicate, aqueous, 33.05 g, 37.64%), aluminum sulfate (aqueous, 3.34 g, 27.18%), H₂SO₄ (aqueous, 4.74 g, 30%), water (33.36 g), and ZSM-23 seed crystals (0.51 g) were combined to form an aqueous zeolite precursor mixture. The combined components (aqueous zeolite precursor mixture) were stirred at 25 °C for 10 minutes to form a gel. The flask containing the gel was transferred to an oven and heated at 170 °C with stirring for approximately 24 hours to obtain a crystalline material containing ZSM-23 and ZSM-5. The crystalline material containing ZSM-23 and ZSM-5 was calcined at 500 °C for one hour and measured multiple times. Some reagent molar ratios and properties of the obtained crystalline hybrid material containing ZSM-23 and ZSM-5 are summarized in Table 1A. Figure 1 shows an electron micrograph of the obtained crystalline hybrid material containing ZSM-23 and ZSM-5, and Figure 3A shows the argon adsorption isotherm of the obtained crystalline hybrid material containing ZSM-23 and ZSM-5. The XRD peaks of the calcined samples of the obtained crystalline hybrid material containing ZSM-23 and ZSM-5 are summarized in Tables 1B and 1C; the XRD patterns corresponding to Table 1B are shown in Figure 2.

[0075] Table 1A

[0076]

[0077] * Relative to the total weight of the solid components.

[0078] Table 1B

[0079]

[0080] From Table 1B, the intensity ratio of the peak at 7.94° 2θ to the peak at 19.72° 2θ can be calculated, and it is 7.54.

[0081] Table 1C

[0082]

[0083] Example 2

[0084] Several runs were conducted to prepare crystalline materials containing ZSM-23 and ZSM-5, similar to Example 1, with variations in the molar ratio of Na to Si and the crystallization time. For all runs, the composition was sodium silicate, aluminum sulfate, H₂SO₄ (aqueous, 30%), water, and ZSM-23 seed crystals; the molar ratios in all runs were Si:Al = 30:1; H₂O:Si = 20:1; and ZSM-23 seed crystals (10 wt% relative to the total weight of solids in the mixture). In all runs, the combined composition was stirred at 25°C for 10 minutes to form a gel, and the flask containing the gel was transferred to an oven and heated and stirred at 170°C to obtain crystalline materials containing ZSM-23 and ZSM-5. The results are summarized in Table 2.

[0085] Table 2

[0086]

[0087] * Comparison run.

[0088] Example 3

[0089] Several runs were conducted to prepare crystalline materials containing ZSM-23 and ZSM-5, similar to Example 1, with variations in the molar ratio of H2O to Si. For all runs, the components were sodium silicate, aluminum sulfate, H2SO4 (aqueous, 30%), water, and ZSM-23 seed crystals; the molar ratios in all runs were Si:Al = 30:1; Na:Si = 0.3:1; and ZSM-23 seed crystals (10 wt% relative to the total weight of solids in the mixture). In all passes, the combined components were stirred at 25°C for 10 minutes to form a gel, and the flask containing the gel was transferred to an oven and heated at 170°C with stirring for approximately 24 hours to obtain crystalline materials containing ZSM-23 and ZSM-5. The results are summarized in Table 3.

[0090] Table 3

[0091]

[0092] Example 4

[0093] Several runs were conducted to prepare crystalline materials containing ZSM-23 and ZSM-5, similar to Example 1, with variations in the amount of ZSM-23 seed crystals. For all runs, the composition was sodium silicate, aluminum sulfate, H₂SO₄ (aqueous, 30%), water, and ZSM-23 seed crystals; the molar ratios in all runs were Si:Al = 30:1; Na:Si = 0.3:1; and H₂O:Si = 20:1. In all passes, the combined composition was stirred at 25°C for 10 minutes to form a gel, and the flask containing the gel was transferred to an oven and heated at 170°C with stirring for approximately 24 hours to obtain crystalline materials containing ZSM-23 and ZSM-5. The results are summarized in Table 4. Figure 3B shows the argon adsorption isotherm of one of the crystalline materials containing ZSM-23 and ZSM-5.

[0094] Table 4

[0095]

[0096] a The total weight of solids relative to the aqueous zeolite precursor mixture.

[0097] b MeSA is an abbreviation for mesopore surface area.

[0098] Example 5

[0099] Several runs were conducted to prepare crystalline materials containing ZSM-23 and ZSM-5, similar to Example 1, with variations in crystallization time. For all runs, the composition was sodium silicate, aluminum sulfate, H₂SO₄ (aqueous, 30%), water, and ZSM-23 seed crystals; the molar ratios in all runs were Si:Al = 36.3:1; Na:Si = 0.166:1; H₂O:Si = 25:1; and 10 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture). In all runs, the combined composition was stirred at 25°C for 10 minutes to form a gel, and the flask containing the gel was transferred to an oven and heated and stirred at 170°C to obtain crystalline materials containing one or more zeolites. The results are summarized in Table 5.

[0100] Table 5

[0101]

[0102] * Comparison run.

[0103] Example 6

[0104] Several runs were conducted to prepare crystalline materials containing ZSM-23 and ZSM-5, similar to Example 1, with variations in crystallization temperature. For all runs, the composition was sodium silicate, aluminum sulfate, H₂SO₄ (aqueous, 30%), water, and ZSM-23 seed crystals; the molar ratios in all runs were Si:Al = 30:1; Na:Si = 0.3:1; H₂O:Si = 20:1; and 10 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture). In all passes, the combined composition was stirred at 25°C for 10 minutes to form a gel, and the flask containing the gel was transferred to an oven and heated and stirred at the crystallization temperature for approximately 24 hours to obtain crystalline materials containing ZSM-23 and ZSM-5. The results are summarized in Table 6.

[0105] Table 6

[0106]

[0107] Example 7

[0108] Olefin cracking tests were conducted in a pulsed fixed-bed reactor system. Each zeolite sample (10 mg) was placed in a quartz reactor tube and heated to and maintained at 480 °C in a continuous 50 mL / min He flow. 1-Hexene (1 µL injection volume) was injected into the He flow at a rate corresponding to a zeolite to olefin ratio of 10:1 (wt / wt). The results are summarized in Tables 7A and 7B below; the reported values ​​are averages of at least two runs. The C6 isomer was considered unreacted feed.

[0109] Table 7A

[0110]

[0111] 1 Prepared according to the following molar ratios: Si:Al = 30:1; Na:Si = 0.3:1; H2O:Si = 20:1; 5 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture); crystallization time of 24 hours; crystallization temperature of 170℃.

[0112] 2 Comparative operation; standard ZSM-5 is prepared using techniques known in the art and is equivalent to commercially available ZSM-5.

[0113] 3 Hydrogen transfer index.

[0114] Table 7B

[0115]

[0116] 1Prepared according to the following molar ratios: Si:Al = 30:1; Na:Si = 0.3:1; H2O:Si = 20:1; 5 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture); crystallization time of 24 hours; crystallization temperature of 170℃.

[0117] 2 Comparative operation; standard ZSM-5 is prepared using techniques known in the art and is equivalent to commercially available ZSM-5.

[0118] 3 The amount of zeolite used in catalytic operation.

[0119] 4 Benzene, toluene, ethylbenzene, and xylene.

[0120] 5 Hydrogen transfer index.

[0121] Example 8

[0122] Olefin cracking tests were conducted in a pulsed fixed-bed reactor system. Prior to catalytic runs, all zeolite samples were treated with 100% steam at 788 °C for 5 h. Each zeolite sample (10 mg) was placed in a quartz reactor tube and heated to and maintained at 480 °C in a continuous 50 mL / min He stream. 1-Hexene (1 µL injection volume) was injected into the He stream at a rate corresponding to a zeolite to olefin ratio of 10:1 (wt / wt). The results are summarized in Table 8 below; the reported values ​​are averages from at least two runs. The C6 isomer was considered unreacted feed.

[0123] Table 8

[0124]

[0125] 1 The results reported in Table 7B above; prepared according to the following molar ratios: Si:Al = 301; Na:Si = 0.3:1; H2O:Si = 20:1; 5 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture); crystallization time of 24 hours; crystallization temperature of 170°C.

[0126] 2 Comparative operation; ZSM-23 and ZSM-5 were prepared by techniques known in the art and are equivalent to commercially available ZSM-23 and ZSM-5.

[0127] Example 9

[0128] In a flask, water glass (sodium silicate, aqueous, 31.50 g, 37.64%), aluminum sulfate (aqueous, 2.03 g, 27.18%), H₂SO₄ (aqueous, 4.98 g, 30%), water (35.45 g), and ZSM-23 seed crystals (1.03 g) were combined to form an aqueous zeolite precursor mixture; the molar ratio was Si:Al = 45:1; Na:Si = 0.3:1; H₂O:Si = 34:1; and 10 wt% ZSM-23 seed crystals (relative to the total weight of solids in the mixture). The combined components were stirred at 25 °C for 10 minutes to form a gel. The flask containing the gel was transferred to an oven and heated at 170 °C for approximately 24 hours to obtain a crystalline material. Some properties of the obtained crystalline material mainly or entirely containing ZSM-23 are summarized in Table 9A. Figure 5 shows the argon adsorption isotherms of the obtained crystalline materials that mainly or completely contain ZSM-23. The XRD peaks of the calcined (500 °C, 1 h) samples of the obtained crystalline materials that mainly or completely contain ZSM-23 are summarized in Tables 9B and 9C; the XRD patterns corresponding to Table 9B are shown in Figure 4.

[0129] Table 9A

[0130]

[0131] Table 9B

[0132]

[0133] From Table 9B, the intensity ratio of the peak at 7.87° 2θ to the peak at 19.65° 2θ can be calculated, and it is 0.98.

[0134] Table 9C

[0135]

[0136] Other embodiments of the present invention include, but are not limited to:

[0137] A) A zeolite composition comprising an MTT framework and an MFI framework, wherein the MTT framework and the MFI framework are physically and / or chemically inseparable from each other without disturbance.

[0138] B) A zeolite composition as in A), wherein the zeolite composition has a silicon to aluminum molar ratio of about 55:1 or less.

[0139] C) A zeolite composition as in A) or B), wherein the MTT framework comprises about 25% to about 95% of the zeolite composition.

[0140] D) A zeolite composition as described in any one of A) to C), wherein said composition has a content of about 100 m 2 / g or greater surface area, and optionally about 0.05 cm² 3 / g or larger micropore volume.

[0141] E) A zeolite composition as described in any one of A) to D), wherein the surface area is about 120 m² 2 / g or larger.

[0142] F) A zeolite composition as described in any of A) to E), wherein the MTT framework is ZSM-23 and / or wherein the MFI framework is pentasil zeolite.

[0143] G) The zeolite composition as in F), wherein the pentasil zeolite is ZSM-5.

[0144] H) A method for preparing a zeolite composition comprising an MTT framework, the method comprising:

[0145] a) Forming an alcohol-free aqueous zeolite precursor mixture comprising a silicon source, an aluminum source, a sodium source, water, and ZSM-23 seed crystals, wherein the molar ratio of sodium to silicon is in the range of about 0.15:1 to about 0.5:1, and the amount of the ZSM-23 seed crystals is about 1 wt% to about 50 wt% relative to the total weight of solids in the aqueous zeolite precursor mixture;

[0146] b) Optionally, the aqueous zeolite precursor mixture is heated at a temperature of about 25°C to about 300°C for about 1 minute to about 200 hours to form a heat-treated precursor; and

[0147] c) Crystallize the aqueous zeolite precursor mixture or the heat-treated precursor by heating it at a temperature of about 60°C to about 300°C for about 1 minute to about 72 hours.

[0148] The method of I) H) wherein the silicon source is selected from sodium silicate, sodium metasilicate, stabilized silica sol, silica gel, polysilicic acid, tetraethyl orthosilicate, fumed silica, precipitated silica, and any combination of two or more of the foregoing; and / or the aluminum source is selected from Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, Al(H2PO4)3, alumina, aluminum trihydrate, aluminum chloride hydrate, aluminum nitrate hydrate, and sodium aluminate, and any combination of two or more of the foregoing.

[0149] The method of any one of J), H) to I), wherein the crystallization step is carried out at one or more temperatures in the range of about 100°C to about 250°C.

[0150] The method of any one of K), H) to J), wherein the crystallization step is carried out for about 15 minutes to about 36 hours.

[0151] L) The method according to any one of claims H) to K), wherein the molar ratio of silicon to aluminum is from about 10:1 to about 250:1; the ratio of sodium to silicon is from about 0.15:1 to about 0.45:1; the ratio of water to silicon is from about 1:1 to about 50:1; and / or about 2 wt% to about 45 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0152] M) The method according to any one of claims H) to K), wherein the molar ratio of silicon to aluminum is from about 10:1 to about 55:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.4:1; the ratio of water to silicon is from about 2:1 to about 35:1; and / or about 4 wt% to about 40 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

[0153] The method of any one of N), H) to M), wherein the optional heating step is performed at one or more temperatures in the range of about 40°C to about 230°C.

[0154] The method is any one of O), H) to N), wherein the optional heating step is performed for about 15 minutes to about 48 hours.

[0155] The method of any one of P), H) to O), wherein the MTT skeleton is ZSM-23.

[0156] Q) A method for cracking olefins at one or more elevated temperatures, the method comprising contacting a gaseous olefin or a mixture of gaseous olefins with a zeolite composition comprising an MTT framework and an MFI framework, the MTT framework and the MFI framework being physically and / or chemically inseparable from each other without disturbance, wherein the zeolite composition has a silicon to aluminum molar ratio of about 55:1 or less.

[0157] R) The method of Q) wherein the elevated temperature is in the range of about 200°C to about 600°C and / or wherein the gaseous olefin has four to about eight carbon atoms.

[0158] S) The method as in Q) or R), wherein the zeolite composition has a silicon to aluminum molar ratio of about 10:1 to about 55:1, and / or wherein the MTT framework comprises about 25% to about 95% of the zeolite composition.

[0159] T) The method of any one of Q) to S), wherein the MTT skeleton is ZSM-23 and / or wherein the MFI skeleton is pentasil zeolite.

[0160] U) The method as in T) wherein the pentasil zeolite is ZSM-5.

[0161] Any component mentioned anywhere in the specification or its claims by its chemical name or formula, whether in the singular or plural, is identified as existing prior to contact with another substance (e.g., another component, solvent, etc.) mentioned by its chemical name or chemical type. What chemical changes, transformations, and / or reactions (if any) occur in the resulting mixture or solution is not important, as these changes, transformations, and / or reactions are natural results of combining the specified components under the conditions required by this disclosure. Therefore, a component is identified as an ingredient to be combined in relation to performing the desired operation or forming the desired composition. Furthermore, even if the claims below refer to a substance, component, and / or ingredient in the present tense (“comprising,” “is,” etc.), such reference refers to the state in which the substance, component, or ingredient exists prior to its first contact, blending, or mixing with one or more other substances, components, and / or ingredients according to this disclosure. Therefore, the fact that a substance, component, or ingredient may lose its original properties through chemical reaction or transformation during contact, blending, or mixing operations is not a practical problem if carried out according to this disclosure and the ordinary skills of a chemist.

[0162] This invention may include, consist of, or substantially consist of the materials and / or processes described herein.

[0163] As used herein, the term "about" to modify the amount of an ingredient used in the compositions or methods of the invention refers to possible variations in numerical quantities, for example, by typical measurements and liquid handling processes used in the preparation of concentrates or the use of solutions in the real world; by negligence or errors in these procedures; by differences in the manufacture, origin, or purity of the ingredients used to make the compositions or carry out the methods; and so on. The term "about" also covers amounts that differ due to different equilibrium conditions resulting from a particular initial mixture. Whether or not modified by the term "about," the claims include quantitative equivalents.

[0164] Unless otherwise expressly stated, the article “a” or “an” (if used herein and as is used herein) is not intended to be limiting and should not be construed as limiting the specification or claims to the single element referred to by the article. Rather, the article “a” or “an” (if used herein and as is used herein) is intended to cover one or more such elements unless the text expressly states otherwise.

[0165] The invention is susceptible to considerable variation in its practice. Therefore, the foregoing description is not intended to limit the invention to, and should not be construed as limiting the invention to the specific examples given above.

Claims

1. A zeolite composition comprising an MTT framework and an MFI framework, wherein the MTT framework and the MFI framework are physically and / or chemically inseparable from each other without disturbance.

2. The zeolite composition according to claim 1, wherein the molar ratio of silicon to aluminum is about 55:1 or less.

3. The zeolite composition according to claim 1, wherein the MTT framework comprises about 25% to about 95% of the zeolite composition.

4. The zeolite composition according to claim 1, wherein the composition has about 100 m 2 / g or greater surface area, and optionally about 0.05 cm² 3 / g or larger micropore volume.

5. The zeolite composition according to claim 1, wherein the surface area is about 120 m². 2 / g or larger.

6. The zeolite composition according to claim 1, wherein the MTT framework is ZSM-23 and / or wherein the MFI framework is pentasil zeolite.

7. The zeolite composition according to claim 6, wherein the pentasil zeolite is ZSM-5.

8. A method for preparing a zeolite composition comprising an MTT framework, the method comprising: A) Forming an alcohol-free aqueous zeolite precursor mixture comprising a silicon source, an aluminum source, a sodium source, water, and ZSM-23 seed crystals, wherein the molar ratio of sodium to silicon is in the range of about 0.15:1 to about 0.5:1, and the amount of the ZSM-23 seed crystals is about 1 wt% to about 50 wt% relative to the total weight of solids in the aqueous zeolite precursor mixture; B) Optionally, the aqueous zeolite precursor mixture is heated at a temperature of about 25°C to about 300°C for about 1 minute to about 200 hours to form a heat-treated precursor; as well as C) Crystallize the aqueous zeolite precursor mixture or the heat-treated precursor by heating it at a temperature of about 60°C to about 300°C for about 1 minute to about 72 hours.

9. The method according to claim 8, wherein the silicon source is selected from sodium silicate, sodium metasilicate, stabilized silica sol, silica gel, polysilicic acid, tetraethyl orthosilicate, fumed silica, precipitated silica, and any combination of two or more thereof; and / or the aluminum source is selected from Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, Al(H2PO4)3, alumina, aluminum trihydrate, aluminum chloride hydrate, aluminum nitrate hydrate, and sodium aluminate, and any combination of two or more thereof.

10. The method of claim 8, wherein the crystallization step is carried out at one or more temperatures in the range of about 100°C to about 250°C.

11. The method of claim 8, wherein the crystallization step is carried out for about 15 minutes to about 36 hours.

12. The method of claim 8, wherein the molar ratio of silicon to aluminum is from about 10:1 to about 250:1; the ratio of sodium to silicon is from about 0.15:1 to about 0.45:1; the ratio of water to silicon is from about 1:1 to about 50:1; and / or about 2 wt% to about 45 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

13. The method of claim 8, wherein the molar ratio of silicon to aluminum is from about 10:1 to about 55:1; the ratio of sodium to silicon is from about 0.2:1 to about 0.4:1; the ratio of water to silicon is from about 2:1 to about 35:1; and / or about 4 wt% to about 40 wt% of ZSM-23 seed crystals are present in the aqueous zeolite precursor mixture relative to the total weight of solids in the mixture.

14. The method of claim 8, wherein the optional heating step is performed at one or more temperatures in the range of about 40°C to about 230°C.

15. The method of claim 8, wherein the optional heating step is performed for about 15 minutes to about 48 hours.

16. The method of claim 8, wherein the MTT skeleton is ZSM-23.

17. A method for catalytic cracking at one or more elevated temperatures, the method comprising contacting a hydrocarbon feedstock with a zeolite composition comprising an MTT framework and an MFI framework, the MTT framework and the MFI framework being physically and / or chemically inseparable from each other without disturbance.

18. The method of claim 17, wherein the hydrocarbon stream is a gaseous olefin or a mixture of gaseous olefins, and wherein the elevated temperature is in the range of about 200°C to about 650°C.

19. The method of claim 17, wherein the zeolite composition has a silicon to aluminum molar ratio of about 10:1 to about 55:1, and / or wherein the MTT framework comprises about 25% to about 95% of the zeolite composition.

20. The method of claim 17, wherein the MTT framework is ZSM-23 and / or wherein the MFI framework is pentasil zeolite.

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