Method for synthesizing mesoporous nano-sized ultra-stable Y zeolite

Abstract

A method for synthesizing a mesoporous nano-sized ultrastable Y zeolite includes combining a microporous Y zeolite having a SiO2 / Al2O3 molar ratio of less than 5.2 with water to form a microporous Y zeolite slurry, and heating the microporous Y zeolite slurry to 30 DEG C to 100 DEG C to form a heated microporous Y zeolite slurry. Further, the method includes sequentially or simultaneously adding 0.1 M to 2.0 M of an ammonium hexafluorosilicate solution and 0.1 M to 2.0 M of an ammonium hydroxide solution to the heated microporous Y zeolite slurry in a drop-by-drop manner to form a treated zeolite solution, and maintaining the treated zeolite solution at 50 DEG C to 100 DEG C. Finally, the method includes filtering and washing the dealuminated solution with water to form an ultra-stable Y zeolite precursor, drying the ultra-stable Y zeolite precursor, and calcining the dried zeolite precursor to form a nano-sized ultra-stable Y zeolite.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Patent Application Serial No. 18 / 059,733, filed on November 29, 2022, titled "Method for Synthesizing Mesoporous Nanoscale Ultrastable Y Zeolite", the entire content of which is incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to nanoscale mesoporous zeolite compositions, as well as methods of synthesizing and using such compositions, and more particularly to a method for synthesizing mesoporous nanoscale ultrastable Y zeolite, including treating microporous Y zeolite with ammonium hexafluorosilicate and ammonium hydroxide. Background Art

[0004] Y - type zeolites are crystalline aluminosilicates that are widely used in heavy oil conversion processes such as hydrocracking and fluid catalytic cracking processes. The feedstocks for these processes are part of crude oil, which has an initial boiling point of 350 degrees Celsius (°C) and an average molecular weight of approximately 200 to 600 or greater. Macroporous materials have a pore size distribution between 50 nanometers (nm) and 1000 nm. Mesoporous materials have a medium pore size distribution, between 2 nm and 50 nm. And microporous materials exhibit a pore size distribution in the range of 0.5 nm to 2 nm. Conventional Y - type zeolites have pore sizes less than 2 nm, which do not allow large molecules to diffuse into and react at the active sites located inside the zeolite. Increasing the pore size and decreasing the zeolite particle size are two effective ways to enhance mass transfer and thus significantly improve catalyst performance.

[0005] Ultrastable Y zeolites have been produced, but their synthesis has traditionally been based on sequential dealumination and desilication, which require additional steps and processes and hinder the economic stability of mesoporous zeolite manufacturing. Summary of the Invention

[0006] Accordingly, there has long been a need to provide more economical schemes for synthesizing mesoporous ultrastable Y zeolites. Additionally, there has long been a need to provide a scheme for synthesizing mesoporous nanoscale ultrastable Y zeolites and taking advantage of the enhanced properties brought about by particle size reduction and increased mesoporosity. The present disclosure addresses this long - standing need by generating mesoporous nanoscale ultrastable Y zeolites according to a method that utilizes microporous Y zeolite and a one - pot synthesis post - treatment with ammonium hexafluorosilicate and ammonium hydroxide.

[0007] According to one embodiment of the present disclosure, a method for synthesizing mesoporous nano-sized ultrastable Y zeolite includes preparing an ammonium hexafluorosilicate solution with a concentration of 0.1 M to 2.0 M; preparing an ammonium hydroxide solution with a concentration of 0.1 M to 2.0 M; combining a microporous Y zeolite having a SiO2 / Al2O3 molar ratio less than 5.2 with 30 mL to 1000 mL of water per gram of the microporous Y zeolite on a dry basis to form a microporous Y zeolite slurry, and heating the microporous Y zeolite slurry to 30 °C to 100 °C to form a heated microporous Y zeolite slurry; and adding the ammonium hexafluorosilicate solution and the ammonium hydroxide solution dropwise to the heated microporous Y zeolite slurry to form a treated zeolite solution. The method further includes maintaining the treated zeolite solution at 50 °C to 100 °C with stirring for an additional 1 hour to 24 hours; filtering and washing the treated zeolite solution with water to form an ultrastable Y zeolite precursor; drying the ultrastable Y zeolite precursor at 80 °C to 150 °C for 6 hours to 24 hours to form a dried zeolite precursor; and calcining the dried zeolite precursor at 250 °C to 600 °C for 1 hour to 8 hours to form the mesoporous nano-sized ultrastable Y zeolite.

[0008] According to a further embodiment of the present disclosure, the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry simultaneously, such that the method further includes mixing the ammonium hexafluorosilicate solution and the ammonium hydroxide solution to form a water treatment solution, and adding the water treatment solution dropwise to the heated microporous Y zeolite slurry within 1 minute to 180 minutes to form a treated zeolite solution.

[0009] According to a further embodiment of the present disclosure, the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry sequentially, first adding the ammonium hexafluorosilicate solution and then adding the ammonium hydroxide solution. Thus, the method further includes adding the ammonium hexafluorosilicate solution dropwise to the heated microporous Y zeolite slurry within 1 minute to 180 minutes to form a dealuminized solution; maintaining the dealuminized solution at 50 °C to 100 °C with stirring for an additional 1 hour to 24 hours; and adding the ammonium hydroxide solution dropwise to the dealuminized solution within 1 minute to 180 minutes to form a treated zeolite solution.

[0010] Other features and advantages of the technology disclosed herein will be set forth in the following detailed description, and some of them will be apparent to those skilled in the art from reading the detailed description or practicing the technology described herein (including the following detailed description and the appended claims).

[0011] It should be understood that the above general description and the following detailed description both present embodiments of the present technology and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed present technology. Additionally, the following description is for illustrative purposes only and is not intended to limit the scope of the claims in any way. Detailed Description

[0012] The present disclosure describes various embodiments related to nanosized mesoporous ultrastable Y zeolite compositions and methods for synthesizing these compositions.

[0013] The description may use the phrases "in some embodiments", "in various embodiments", "in one embodiment", or "in embodiments", which may each refer to one or more of the same or different embodiments. Additionally, the terms "comprising", "including", "having", etc., used with respect to the embodiments of the present disclosure are synonyms.

[0014] Zeolite catalysts are commonly used in heavy oil conversion processes such as hydrocracking and fluid catalytic cracking processes. For example, crude oil can first be hydrotreated and then passed through a hydrocracking catalyst to remove unwanted components such as sulfur, nitrogen, and metals, and to convert large molecular weight hydrocarbons (complex aromatics or unsaturated hydrocarbons) into naphtha, kerosene, gasoline, diesel, or high-quality lubricating oil. The catalyst used for the hydroprocessing operation has two functions: one is to crack large molecular weight hydrocarbons, and the other is to hydrogenate unsaturated molecules. However, the small pore diameters of the most widely used zeolites (beta zeolite and Y-type zeolite) in hydrocracking catalysts prevent large molecules in the heavy oil fraction from diffusing into the active sites located inside the zeolite, thereby having a negative impact on the performance of the catalyst. This results in a decrease in catalyst activity and possible catalyst deactivation. The low diffusion efficiency of large molecules can be improved by increasing the pore diameter of the zeolite catalyst, or by decreasing the particle size of the zeolite catalyst, or by combining these two characteristics. Disclosed herein are mesoporous ultrastable Y zeolite compositions having an average pore diameter of 2.5 nm to 6 nm. By increasing and facilitating the diffusion of large molecules into the active sites located inside the zeolite, increasing the mesoporosity and average pore diameter during the synthesis of the ultrastable Y zeolite catalyst affects the performance of the ultrastable Y zeolite catalyst.

[0015] Post-synthesis or "top-down" modification of Y zeolite, such as steaming and acid or chemical dealumination techniques, has been used to improve the hydrothermal stability of Y zeolite to prepare USY (ultrastable Y) zeolite. There have also been attempts to combine framework desilication using known techniques with subsequent dealumination with ammonium hexafluorosilicate (AHFS) or steaming to produce USY zeolite with defect-guided mesoporosity. However, this sequential desilication-dealumination treatment is both time-consuming and increases the complexity and cost of the synthesis process. An alternative method for synthesizing mesoporous nanosized ultrastable Y zeolite has been developed according to embodiments of the present disclosure, which utilizes a one-pot synthesis method to perform post-synthesis modification of nanosized Y zeolite with ammonium hexafluorosilicate as a chelating agent and ammonium hydroxide. Ammonium hydroxide can be added simultaneously with ammonium hexafluorosilicate or after ammonium hexafluorosilicate. This upgrading synthesis method increases the mesoporosity and pore volume, reduces the sodium (Na) content in the zeolite, reduces the operating cost, and enhances the economic feasibility of manufacturing mesoporous nanosized ultrastable Y zeolite.

[0016] Embodiments of Y-type zeolites that can be incorporated into hydrotreating catalysts are generally described in the present disclosure. The present disclosure relates to methods for producing such zeolites and the properties and structures of the zeolites produced. In some embodiments, the hydrotreating catalyst can be used to crack aromatics in heavy oil during a pretreatment process that can be carried out prior to steam cracking or other downstream processing. According to one or more embodiments, the zeolite compositions formed according to the present disclosure can include relatively small particle sizes and can have mesoporosity. Such zeolite materials can be referred to throughout the present disclosure as "mesoporous nanosized ultrastable Y zeolites". As used throughout the present disclosure, "zeolite" refers to a microporous inorganic material having regular intracrystalline cavities and molecular-sized channels. The microporous structure of the zeolite (e.g., pore diameters from 0.3 nm to 1 nm) can provide a large surface area and the desired size / shape selectivity, which can be beneficial for catalysis. The mesoporous zeolites described can include, for example, aluminosilicates, titanosilicates, or pure silicates. In one or more embodiments, the zeolites described can include micropores (present in the microstructure of the zeolite) and additionally include mesopores. As used throughout the present disclosure, micropores refer to pores in the zeolite structure having a diameter less than or equal to 2 nm and greater than or equal to 0.1 nm, and mesopores refer to pores in the zeolite structure having a diameter greater than 2 nm and less than or equal to 50 nm. The zeolites currently described can be characterized as Y-type (i.e., having an aluminosilicate FAU framework type).

[0017] Disclosed herein are specific synthesis methods for these nano-sized mesoporous zeolite compositions. According to the present disclosure, a method for synthesizing mesoporous nano-sized ultrastable Y zeolite includes preparing an ammonium hexafluorosilicate solution of 0.1 M to 2.0 M and preparing an ammonium hydroxide solution of 0.1 M to 2.0 M. Microporous Y zeolite having a SiO2 / Al2O3 molar ratio of less than 5.2 is combined with 30 mL to 1000 mL of water per gram of microporous Y zeolite on a dry basis to form a microporous Y zeolite slurry, and the microporous Y zeolite slurry is heated to 30 °C to 100 °C to form a heated microporous Y zeolite slurry. Then the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added dropwise to the heated microporous Y zeolite slurry to form a treated zeolite solution, and the treated zeolite solution is maintained at 50 °C to 100 °C for an additional 1 hour to 24 hours with stirring. The treated zeolite solution is filtered and washed to form an ultrastable Y zeolite precursor. Finally, the ultrastable Y zeolite precursor is dried at 80 °C to 150 °C for 6 hours to 24 hours to form a dried zeolite precursor, and the dried zeolite precursor is calcined at 250 °C to 600 °C for 1 hour to 8 hours to form nano-sized ultrastable Y zeolite. The method for synthesizing mesoporous nano-sized ultrastable Y zeolite and each specific step are further discussed in detail below.

[0018] In one or more embodiments, an aqueous ammonium hexafluorosilicate (AHFS) solution is formed. Specifically, AHFS and water are mixed to form an ammonium hexafluorosilicate solution. According to various embodiments, AHFS and water are mixed to form a solution of 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, or 0.1 M to 2.0 M. AHFS and water are mixed until AHFS is completely dissolved to form an ammonium hexafluorosilicate solution.

[0019] In one or more embodiments, an aqueous ammonium hydroxide solution is formed. Specifically, ammonium hydroxide and water are mixed to form an ammonium hydroxide solution. According to various embodiments, ammonium hydroxide and water are mixed to form a solution of 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, 0.1 M to 2.0 M, or 0.1 M to 2.0 M. Ammonium hydroxide and water are mixed until ammonium hexafluorosilicate is completely integrated to form an ammonium hexafluorosilicate solution. In one or more embodiments, ammonium hexafluorosilicate is added as a concentrated ammonium hexafluorosilicate solution (such as a 14 M solution) to form an ammonium hexafluorosilicate solution within the disclosed range of 0.1 M to 2.0 M.

[0020] In one or more embodiments, the ammonium hydroxide solution is generated in-situ in the ammonium hexafluorosilicate solution. Specifically, ammonium hydroxide can be added as a concentrated solution to the ammonium hexafluorosilicate solution to generate a final solution consistent with the ammonium hydroxide solution.

[0021] In one or more embodiments, the microporous Y zeolite is combined with water to form a microporous Y zeolite slurry. In various embodiments, the microporous Y zeolite can be combined with 30 milliliters (ml) to 1000 ml, 100 ml to 800 ml, 100 ml to 600 ml, 100 ml to 500 ml, 100 ml to 400 ml, 100 ml to 300 ml, or 100 ml to 200 ml of water per gram of nanosized Y zeolite on a dry basis to form a microporous Y zeolite slurry. Subsequently, in various embodiments, the microporous Y zeolite slurry is heated to 30°C to 100°C, 50°C to 100°C, 70°C to 95°C, 80°C to 100°C, or about 90°C with stirring. During the AHFS treatment, heating can accelerate the removal of aluminum from the zeolite framework, and at the same time, the silicon in the AHFS can backfill the voids left after aluminum removal. If the temperature is not high enough, the reaction rate may be unacceptably slow and difficult to meet practical applications.

[0022] In one or more embodiments, the microporous Y zeolite has an SiO2 / Al2O3 molar ratio of less than 5.2. Additionally, in various embodiments, the microporous Y zeolite comprises less than 4 wt.%, less than 3.5 wt.%, or less than 3 wt.% of Na2O. Examples of such microporous Y zeolites include CBV-300, CBV-400, and CBV-500, each of which is available from Zeolyst International, Inc.

[0023] In one or more embodiments, an ammonium hexafluorosilicate solution and an ammonium hydroxide solution are added to the heated microporous Y zeolite slurry to form a treated zeolite solution. The addition of the ammonium hexafluorosilicate solution and the ammonium hydroxide solution can be considered to be added dropwise. When adding the ammonium hexafluorosilicate solution and the ammonium hydroxide solution on an industrial scale, a liquid pump with precise flow control is used.

[0024] In one or more embodiments, the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry simultaneously. For example, the ammonium hexafluorosilicate solution and the ammonium hydroxide solution according to the various disclosed embodiments can be combined together to form a water treatment solution. Subsequently, the water treatment solution can be added to the heated microporous Y zeolite slurry in a dropwise manner to add the ammonium hexafluorosilicate solution and the ammonium hydroxide solution simultaneously. In various embodiments, the water treatment solution can be added to the heated microporous Y zeolite slurry over a period of 1 minute to 180 minutes, 10 minutes to 180 minutes, 30 minutes to 180 minutes, 60 minutes to 180 minutes, 75 minutes to 180 minutes, or 90 minutes to 180 minutes to form a treated zeolite solution.

[0025] In one or more embodiments where an ammonium hexafluorosilicate solution and an ammonium hydroxide solution are added simultaneously, the aqueous treatment solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

[0026] In one or more embodiments where the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added sequentially, the ammonium hexafluorosilicate solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis, and the ammonium hydroxide solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

[0027] In one or more embodiments, the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added sequentially to the microporous Y zeolite slurry, with the ammonium hexafluorosilicate solution added first and the ammonium hydroxide solution added subsequently. For example, according to the various disclosed embodiments, in a first operation, the ammonium hexafluorosilicate solution can be added dropwise to the heated microporous Y zeolite slurry to form a dealumination solution. In various embodiments, the ammonium hexafluorosilicate solution can be added to the heated microporous Y zeolite slurry over a period of 1 minute to 180 minutes, 10 minutes to 180 minutes, 30 minutes to 180 minutes, 60 minutes to 180 minutes, 75 minutes to 180 minutes, or 90 minutes to 180 minutes to form a dealumination solution. Subsequently, according to the various disclosed embodiments, in a second operation, the ammonium hydroxide solution can be added dropwise to the dealumination solution to form a treated zeolite solution. In various embodiments, the ammonium hydroxide solution can be added to the dealumination solution over a period of 1 minute to 180 minutes, 10 minutes to 180 minutes, 30 minutes to 180 minutes, 60 minutes to 180 minutes, 75 minutes to 180 minutes, or 90 minutes to 180 minutes to form a treated zeolite solution.

[0028] In one or more embodiments, the treated zeolite solution is maintained at 50°C to 100°C for an additional 1 hour to 24 hours with stirring. It can be understood that dealumination and silicon filling with AHSF is a slow process, so a holding period is required after the addition of AHSF is completed to ensure the completion of the reaction. In various further embodiments, the treated zeolite solution is maintained at 55°C to 100°C, 60°C to 100°C, 70°C to 100°C, 80°C to 100°C, or 90°C to 100°C for an additional 1 hour to 24 hours, 1 hour to 20 hours, 1 hour to 16 hours, 1 hour to 12 hours, 1 hour to 8 hours, 1 hour to 4 hours, or 1 hour to 2 hours with stirring.

[0029] In one or more embodiments of successively adding ammonium hexafluorosilicate solution and ammonium hydroxide solution, before adding the ammonium hydroxide solution to the dealuminizing solution, the dealuminizing solution can be maintained at 50°C to 100°C for an additional 1 hour to 24 hours with stirring. In various further embodiments, the dealuminizing solution is maintained at 55°C to 100°C, 60°C to 100°C, 70°C to 100°C, 80°C to 100°C, or 90°C to 100°C for an additional 1 hour to 24 hours, 1 hour to 20 hours, 1 hour to 16 hours, 1 hour to 12 hours, 1 hour to 8 hours, 1 hour to 4 hours, or 1 hour to 2 hours with stirring.

[0030] In one or more embodiments, the zeolite solution is filtered and the collected product is washed with water to form a ultrastable Y zeolite precursor. Filtering and washing the zeolite solution involves separating the solid product from any liquid product in the treated zeolite solution using a centrifuge or other filtration scheme. The solid product is then mixed with water to wash the solid product. The resulting solution is then separated using a centrifuge. In various embodiments, the washing and separation can be repeated, for a total of 1, 2, 3, 4, or 5 washes.

[0031] In one or more embodiments, the wet filter cake comprising the ultrastable Y zeolite precursor is dried to form a dried zeolite precursor. In various embodiments, the ultrastable Y zeolite precursor can be dried at a high drying temperature of 80°C to 150°C, 90°C to 140°C, 90°C to 130°C, 90°C to 120°C, 95°C to 120°C, 100°C to 120°C, 100°C to 115°C, or 100°C to 110°C. Additionally, in various embodiments, the ultrastable Y zeolite precursor can be dried at the high drying temperature for a period of 6 hours to 24 hours, 8 hours to 18 hours, 10 hours to 18 hours, 6 hours to 18 hours, 8 hours to 14 hours, or 8 hours to 12 hours. Alternatively, the period of drying at the high drying temperature can be considered overnight.

[0032] In one or more embodiments, the dried zeolite precursor is calcined to form nano-sized ultrastable Y zeolite. In various embodiments, the dried zeolite precursor can be calcined at a high calcination temperature of 250°C to 600°C, 300°C to 600°C, 400°C to 600°C, 450°C to 600°C, 500°C to 600°C, 550°C to 600°C, or approximately 550°C. Additionally, in various embodiments, the dried zeolite precursor can be calcined at the high calcination temperature for a period of 1 hour to 8 hours, 2 hours to 6 hours, 3 hours to 6 hours, 4 hours to 8 hours, 4 hours to 5 hours, or approximately 4 hours. In one or more embodiments, the heating rate during calcination is 1°C to 3°C per minute.

[0033] The properties of the nano-sized ultrastable Y zeolite include a surface area of the nano-sized ultrastable Y zeolite greater than 590 m 2 / g. In some embodiments, the surface area of the nano-sized ultrastable Y zeolite can be from 590 m 2 / g to 800 m 2 / g, from 590 m 2 / g to 760 m 2 / g, from 590 m 2 / g to 700 m 2 / g or from 590 m 2 / g to 650 m 2 / g. The average particle size is measured based on the Brunauer-Emmett-Teller (BET) technique. The pore volume of the nano-sized ultrastable Y zeolite can be greater than 0.4 ml / g. In some embodiments, the pore volume of the nano-sized ultrastable Y zeolite can be from 0.4 ml / g to 0.8 ml / g, from 0.4 ml / g to 0.7 ml / g, from 0.4 ml / g to 0.6 ml / g or from 0.4 ml / g to 0.5 ml / g. The average pore diameter of the nano-sized ultrastable Y zeolite can be from 2.5 nm to 6 nm. In some embodiments, the average pore diameter of the nano-sized ultrastable Y zeolite can be from 2.5 nm to 5.5 nm, from 2.5 nm to 5 nm, from 2.5 nm to 4 nm or from 2.5 nm to 3.5 nm. Alternatively, in one or more embodiments, the average pore diameter of the nano-sized ultrastable Y zeolite can be greater than 2.5 nm. The pore diameter can be determined from the surface area and the pore volume. Based on spherical particles, four times the pore volume divided by the surface area gives the pore diameter.

[0034] In one or more embodiments, the mesoporous nano-sized ultrastable Y zeolite includes a molar ratio of SiO2 to Al2O3 of 8 to 10.

[0035] Most of the pore volume of the mesoporous nano-sized ultrastable Y zeolite is mesopore volume. In various embodiments, at least 60 volume %, at least 65 volume %, at least 70 volume %, at least 75 volume % or at least 80 volume % of the pore volume of the mesoporous nano-sized ultrastable Y zeolite is mesopore.

[0036] The mesoporous nano-sized ultrastable Y zeolite also includes a relatively low Na2O level. It is understood that Na2O can reduce the acidity of the zeolite and greatly reduce the cracking activity of the final catalyst containing the zeolite, so it is necessary to avoid using such substances in the Y zeolite. In various embodiments, the mesoporous nano-sized ultrastable Y zeolite includes a Na2O level of less than 1 weight % (wt.%), less than 0.9 wt.%, less than 0.8 wt.%, less than 0.7 wt.%, less than 0.6 wt.% or less than 0.5 wt.%.

[0037] Examples

[0038] The method for synthesizing mesoporous nanosized ultrastable Y zeolite will be further elaborated through the following examples. The examples are illustrative in nature and should not be construed as limiting the subject matter of the present disclosure.

[0039] Three samples of mesoporous Y zeolite were prepared to compare the synthesis using only AHFS with the synthesis using a combination of ammonium hexafluorosilicate and ammonium hydroxide according to the method of the present disclosure. Invention Example 1 provides the synthesis of mesoporous nanosized ultrastable Y zeolite using a treatment with ammonium hexafluorosilicate and ammonium hydroxide simultaneously. Invention Example 2 provides the synthesis of mesoporous nanosized ultrastable Y zeolite using a treatment with ammonium hexafluorosilicate and ammonium hydroxide sequentially. Comparative Example 3 provides the synthesis of mesoporous Y zeolite using only AHFS treatment.

[0040] Invention Example 1

[0041] For Invention Example 1, a treatment with AFHS and ammonium hydroxide after synthesis was used simultaneously to prepare mesoporous Y zeolite. In a first container, 67 grams of CBV-300 zeolite (available from Zeolyst International, Conshohocken, PA) and 300 ml of deionized water were mixed and heated to 90 °C. In a separate container, an aqueous solution of ammonium hexafluorosilicate and ammonium hydroxide was prepared by mixing 16.5 grams of AHFS from Sigma Aldrich with 200 ml of water until the AHFS was dissolved, and then adding 2.752 ml of NH4OH solution from Sigma Aldrich. The resulting aqueous solution of ammonium hexafluorosilicate and ammonium hydroxide was equivalent to a 0.46 M ammonium hexafluorosilicate solution and a 0.2 M ammonium hydroxide solution, collectively referred to as the water treatment solution. Then, the water treatment solution was added dropwise to the first container containing the zeolite solution over a 2-hour period. Then the temperature of the mixture in the first container was raised to 90 °C to 95 °C and maintained for 2 hours with stirring. Stirring was stopped and the mixture was allowed to settle for about 10 minutes. Subsequently, the resulting product was filtered and washed. Specifically, the resulting product was filtered through filter paper and separated from the resulting solution. The filter cake on the filter paper was placed in a beaker, combined with 1000 ml of water, stirred at room temperature for about 30 minutes, and then filtered again. Such a filtration and washing process was completed 3 times in total. The obtained wet filter cake was dried overnight at 110 °C and then calcined at 550 °C for 4 hours with a heating rate of 2 °C per minute.

[0042] Invention Example 2

[0043] For Invention Example 2, mesoporous Y zeolite was prepared by sequentially using post-synthesis AFHS and ammonium hydroxide treatments. In a first container, 67 grams of CBV-300 zeolite (available from Zeolyst International, Conshohocken, PA) was mixed with 300 ml of deionized water and heated to 90 °C. In a separate container, an aqueous solution of ammonium hexafluorosilicate was prepared by mixing 16.5 grams of AHFS from Sigma Aldrich with 200 ml of water until the AHFS was dissolved to form an ammonium hexafluorosilicate solution. The resulting ammonium hexafluorosilicate solution was equivalent to a 0.46 M ammonium hexafluorosilicate solution. Then, the ammonium hexafluorosilicate solution was added dropwise to the first container containing the zeolite solution over a 2-hour period. Then the temperature of the mixture in the first container was raised to 90 °C to 95 °C and maintained with stirring for 1 hour. Then 100 ml of a 0.4 M ammonium hydroxide solution from Sigma Aldrich was added dropwise to the first container over a 1-hour period. Then the temperature of the mixture in the first container was maintained at 90 °C to 95 °C with stirring for an additional 1 hour. Stirring was stopped and the mixture was allowed to settle for about 10 minutes. Subsequently, the resulting product was filtered and washed in the same manner as in Invention Example 1. The resulting wet filter cake was dried overnight at 110 °C and then calcined at 550 °C for 4 hours at a heating rate of 2 °C per minute.

[0044] Comparative Example 3

[0045] For Comparative Example 3, mesoporous Y zeolite was prepared using only post-synthesis AFHS treatment. In a first container, 67 grams of CBV-300 zeolite (available from Zeolyst International, Conshohocken, PA) was mixed with 300 ml of deionized water and heated to 90 °C. In a separate container, an aqueous solution of ammonium hexafluorosilicate was prepared by mixing 16.5 grams of AHFS from Sigma Aldrich with 200 ml of water to obtain a 0.46 M solution. Then, the aqueous solution of ammonium hexafluorosilicate was added dropwise to the first container containing the zeolite solution over a 2-hour period. Then the temperature of the mixture in the first container was raised to 90 °C to 95 °C and maintained with stirring for 2 hours. Stirring was stopped and the mixture was allowed to settle for about 10 minutes. Subsequently, the resulting product was filtered and washed in the same manner as in Invention Example 1. The resulting wet filter cake was dried overnight at 110 °C and then calcined at 550 °C for 4 hours at a heating rate of 2 °C per minute.

[0046] The properties of the mesoporous Y zeolites of Invention Example 1, Invention Example 2, and Comparative Example 3 are provided in Table 1 below. Table 1 also includes the properties of CBV-300 zeolite as a reference. Using CBV-300 (Zeolyst International) as a reference, the XRD crystallinity was determined.

[0047] Table 1: Properties of Mesoporous Nanoscale Y Zeolites

[0048]

[0049] As shown in Table 1, the zeolites of Invention Example 1 and Invention Example 2 exhibited improved properties compared to the zeolite of Comparative Example 3. Specifically, comparing Invention Example 1 and Invention Example 2 with Comparative Example 3, it can be seen that according to the present disclosure, the use of AHFS and ammonium hydroxide treatment achieved a larger pore volume and an increased surface area.

[0050] Based on the above, it should now be understood that various aspects of a method for synthesizing mesoporous nanoscale ultrastable Y zeolite are disclosed herein.

[0051] According to a first aspect of the present disclosure, a method for synthesizing mesoporous nanoscale ultrastable Y zeolite includes preparing an ammonium hexafluorosilicate solution having a concentration of 0.1 M to 2.0 M; preparing an ammonium hydroxide solution having a concentration of 0.1 M to 2.0 M; combining a microporous Y zeolite having a SiO2 / Al2O3 molar ratio of less than 5.2 with 30 mL to 1000 mL of water per gram of the microporous Y zeolite on a dry basis to form a microporous Y zeolite slurry, and heating the microporous Y zeolite slurry to 30°C to 100°C to form a heated microporous Y zeolite slurry; adding the ammonium hexafluorosilicate solution and the ammonium hydroxide solution dropwise to the heated microporous Y zeolite slurry to form a treated zeolite solution; maintaining the treated zeolite solution at 50°C to 100°C with stirring for an additional 1 hour to 24 hours; filtering and washing the treated zeolite solution with water to form an ultrastable Y zeolite precursor; drying the ultrastable Y zeolite precursor at 80°C to 150°C for 6 hours to 24 hours to form a dried zeolite precursor; and calcining the dried zeolite precursor at 250°C to 600°C for 1 hour to 8 hours to form a mesoporous nanoscale ultrastable Y zeolite.

[0052] A second aspect includes the method according to the first aspect, wherein the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry simultaneously.

[0053] A third aspect includes the method according to the second aspect, wherein the method further includes mixing the ammonium hexafluorosilicate solution and the ammonium hydroxide solution to form a water treatment solution, and adding the water treatment solution dropwise to the heated microporous Y zeolite slurry within 1 minute to 180 minutes to form a treated zeolite solution.

[0054] The fourth aspect includes the method described in the third aspect, wherein the water treatment solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

[0055] The fifth aspect includes the method described in the first aspect, wherein an ammonium hexafluorosilicate solution and an ammonium hydroxide solution are sequentially added to the microporous Y zeolite slurry, the ammonium hexafluorosilicate solution is added first, and then the ammonium hydroxide solution is added.

[0056] The sixth aspect includes the method described in the fifth aspect, wherein the method further includes adding the ammonium hexafluorosilicate solution dropwise to the heated microporous Y zeolite slurry over 1 minute to 180 minutes to form a dealuminated solution; maintaining the dealuminated solution at 50°C to 100°C with stirring for an additional 1 hour to 24 hours; and adding the ammonium hydroxide solution dropwise to the dealuminated solution over 1 minute to 180 minutes to form a treated zeolite solution.

[0057] The seventh aspect includes the method described in the sixth aspect, wherein the ammonium hexafluorosilicate solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis, and the ammonium hydroxide solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

[0058] The eighth aspect includes the method described in any one of the first to seventh aspects, wherein based on BET measurement, the mesoporous nanosized ultrastable Y zeolite includes a surface area greater than 590 m 2 / g.

[0059] The ninth aspect includes the method described in any one of the first to eighth aspects, wherein the mesoporous nanosized ultrastable Y zeolite includes a pore volume greater than 0.4 ml / g.

[0060] The tenth aspect includes the method described in any one of the first to ninth aspects, wherein the mesoporous nanosized ultrastable Y zeolite includes an average pore diameter of 2.5 nm to 6 nm.

[0061] The eleventh aspect includes the method described in any one of the first to tenth aspects, wherein the mesoporous nanosized ultrastable Y zeolite includes a molar ratio of SiO2 to Al2O3 of 8 to 10.

[0062] The twelfth aspect includes the method described in any one of the first to eleventh aspects, wherein the mesoporous nanosized ultrastable Y zeolite includes a Na2O level of less than 1 wt%.

[0063] The thirteenth aspect includes the method described in any one of the first to twelfth aspects, wherein the microporous Y zeolite slurry is heated to 80°C to 100°C.

[0064] The fourteenth aspect includes the method described in the third aspect or the fourth aspect, wherein the treated zeolite solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours.

[0065] The fifteenth aspect includes the method described in the sixth aspect or the seventh aspect, wherein the dealumination solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours, and the treated zeolite solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours.

[0066] The sixteenth aspect includes the method described in any one of the first aspect to the fifteenth aspect, wherein the ultrastable Y zeolite precursor is dried at 100 °C to 120 °C for 8 hours to 12 hours.

[0067] The seventeenth aspect includes the method described in any one of the first aspect to the sixteenth aspect, wherein the zeolite precursor is calcined at 550 °C to 600 °C for 3 hours to 6 hours to form mesoporous nanosized ultrastable Y zeolite.

[0068] The eighteenth aspect includes the method described in any one of the first aspect to the seventeenth aspect, wherein the heating rate during calcination is 1 °C to 3 °C per minute.

[0069] Those skilled in the art should understand that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter. Therefore, this specification is intended to cover various modifications and variations of the described embodiments, provided that these modifications and variations are within the scope of the appended claims and their equivalents.

[0070] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0071] The present disclosure provides ranges throughout. It is contemplated that each discrete value encompassed by the range is also included. Additionally, it is equally contemplated that ranges formed by each discrete value encompassed by the explicitly disclosed range are also included. For the sake of brevity, this general indication is provided without explicit indication after each disclosed range. Furthermore, it should be understood that any two quantitative values assigned to a property can form a range for that property, and all combinations of ranges formed by all the described quantitative values of a given property are contemplated in the present disclosure.

[0072] As used in this disclosure and the appended claims, the words "comprising", "having", and "including" and all their grammatical variants are intended to have an open, non - restrictive meaning, excluding no additional elements or steps.

[0073] Throughout the description of this specification, numerous details are set forth in order to provide a thorough understanding of the various embodiments. In other instances, well-known processes, devices, and systems may not be described in particular detail so as not to unnecessarily obscure the various embodiments, but these are available to those skilled in the art. Additionally, in order not to obscure the various embodiments, the illustrations of the various embodiments may omit certain features or details.

Claims

1. A method for synthesizing mesoporous nanosized ultrastable Y zeolite, the method comprising: Preparing an ammonium hexafluorosilicate solution having a concentration of 0.1M to 2.0M; Preparing an ammonium hydroxide solution having a concentration of 0.1M to 2.0M; Combining a microporous Y zeolite having a SiO2 / Al2O3 molar ratio of less than 5.2 with 30 mL to 1000 mL of water per gram of the microporous Y zeolite on a dry basis to form a microporous Y zeolite slurry, and heating the microporous Y zeolite slurry to 30°C to 100°C to form a heated microporous Y zeolite slurry; Adding the ammonium hexafluorosilicate solution and the ammonium hydroxide solution dropwise to the heated microporous Y zeolite slurry to form a treated zeolite solution; Maintaining the treated zeolite solution at 50°C to 100°C with stirring for an additional 1 hour to 24 hours; Filtering and washing the treated zeolite solution with water to form an ultrastable Y zeolite precursor; Drying the ultrastable Y zeolite precursor at 80°C to 150°C for 6 hours to 24 hours to form a dried zeolite precursor; And Calcining the dried zeolite precursor at 250°C to 600°C for 1 hour to 8 hours to form the mesoporous nanosized ultrastable Y zeolite.

2. The method according to claim 1, wherein the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry simultaneously.

3. The method according to claim 2, wherein the method further comprises: Mixing the ammonium hexafluorosilicate solution and the ammonium hydroxide solution to form a water treatment solution; And Adding the water treatment solution dropwise to the heated microporous Y zeolite slurry within 1 minute to 180 minutes to form the treated zeolite solution.

4. The method according to claim 1, wherein the ammonium hexafluorosilicate solution and the ammonium hydroxide solution are added to the microporous Y zeolite slurry sequentially, first adding the ammonium hexafluorosilicate solution and then adding the ammonium hydroxide solution.

5. The method according to claim 4, wherein the method further comprises: Adding the ammonium hexafluorosilicate solution dropwise to the heated microporous Y zeolite slurry within 1 minute to 180 minutes to form a dealuminized solution; Maintaining the dealuminized solution at 50°C to 100°C with stirring for an additional 1 hour to 24 hours; And Adding the ammonium hydroxide solution dropwise to the dealuminized solution within 1 minute to 180 minutes to form the treated zeolite solution.

6. The method according to claim 3, wherein the water treatment solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

7. The method according to claim 5, wherein the ammonium hexafluorosilicate solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis, and the ammonium hydroxide solution has a weight ratio of 0.1 to 1.0 relative to the microporous Y zeolite on a dry basis.

8. The method according to any one of claims 1 to 7, wherein based on BET measurement, the mesoporous nano-sized ultrastable Y zeolite comprises a surface area of greater than 590 m 2 / g.

9. The method according to any one of claims 1 to 8, wherein the mesoporous nanosized ultrastable Y zeolite has a pore volume greater than 0.4 ml / g.

10. The method according to any one of claims 1 to 9, wherein the mesoporous nano-sized ultrastable Y zeolite has an average pore diameter of 2.5 nm to 6 nm.

11. The method according to any one of claims 1 to 10, wherein the mesoporous nano-sized ultrastable Y zeolite has a molar ratio of SiO2 to Al2O3 of 8 to 10.

12. The method according to any one of claims 1 to 11, wherein the mesoporous nano-sized ultrastable Y zeolite has a Na2O level of less than 1 wt%.

13. The method according to claim 3, wherein the treated zeolite solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours.

14. The method according to claim 5 or 6, wherein the dealumination solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours, and the treated zeolite solution is maintained at 90 °C to 100 °C for an additional 1 hour to 24 hours.

15. The method according to any one of claims 1 to 14, wherein the heating rate during calcination is 1 °C to 3 °C per minute.

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