Method for synthesizing mesoporous nano-sized beta zeolites

Abstract

Methods for the synthesis of mesoporous nano-sized beta zeolites are described. The method includes preparing an aqueous cetyltrimethylammonium bromide (CTAB) solution, and adding nano-sized zeolite particles having a BEA framework type, a particle size of less than or equal to 100 nm, and a microporous framework including a plurality of micropores having a diameter of less than or equal to 2 nm to form a second solution. The second solution does not include a base. The method further includes transferring the second solution to an autoclave operating at 25 DEG C to 200 DEG C for 3 hours to 24 hours to form a colloid; washing the colloid with water to form a washed colloid; drying the washed colloid at 100 DEG C to 200 DEG C for 4 hours to 24 hours to form a zeolite precursor; and calcining the zeolite precursor at 250 DEG C to 600 DEG C for 1 to 8 hours to form a mesoporous nano-sized beta zeolite.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Patent Application Serial No. 18 / 059,722, filed on November 29, 2022, titled "Method for Synthesizing Mesoporous Nanoscale Beta Zeolite", the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure generally relates to nanoscale mesoporous zeolite compositions and methods of synthesizing and using these compositions, and more particularly to a method for synthesizing mesoporous nanoscale beta zeolite without alkali dealumination. Background art

[0004] Beta zeolite is a crystalline aluminosilicate that is widely used in heavy oil conversion processes such as hydrocracking and fluid catalytic cracking processes. The feedstock for these processes is a portion of crude oil with an initial boiling point of 350 degrees Celsius (°C) and an average molecular weight of about 200 to 600 or higher. 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. Microporous materials have a pore size distribution ranging from 0.5 nm to 2 nm. Conventional beta zeolite has a pore size of less than 2 nm, which does not allow large molecules to diffuse in and react at the active sites located inside the zeolite. Increasing the pore size and reducing the zeolite particle size are two effective ways to enhance mass transfer and thus significantly improve the catalyst performance.

[0005] Nanoscale beta zeolites have been produced, but their synthesis traditionally involves treatment with an alkaline solution to dealuminate the zeolite, which requires subsequent ion exchange to remove residual ions from the alkaline solution. This subsequent ion exchange treatment reduces the yield, thus hindering the economic stability of mesoporous zeolite manufacturing. Summary of the invention

[0006] Accordingly, there has long been a need to provide a more economical solution for synthesizing mesoporous nanoscale beta zeolite. The present disclosure meets this long - standing need by using a method that does not require the use of an alkaline solution for dealumination during the zeolite preparation process. It is understood that eliminating dealumination with an alkaline solution both increases the zeolite yield and reduces the operating cost through fewer process operations.

[0007] According to one embodiment of the present disclosure, a method for synthesizing mesoporous nanosized beta zeolite includes: preparing an aqueous cetyltrimethylammonium bromide (CTAB) solution; adding nanosized zeolite particles having a particle size less than or equal to 100 nm to the aqueous CTAB solution to form a second solution, wherein the second solution does not include an alkali, and the nanosized zeolite particles include a microporous framework and a BEA framework type, the microporous framework including a plurality of micropores having a diameter less than or equal to 2 nm; transferring the second solution to an autoclave operating at 25 °C to 200 °C for 3 hours to 24 hours to form a colloid; washing the colloid with water to form a washed colloid; drying the washed colloid at 100 °C to 200 °C for 4 hours to 24 hours to form a zeolite precursor; and calcining the zeolite precursor at 250 °C to 600 °C for 1 hour to 8 hours to form mesoporous nanosized beta zeolite.

[0008] Other features and advantages of the techniques disclosed herein will be set forth in the detailed description that follows, and in part will be apparent to those skilled in the art from the description or recognized by practicing the techniques described herein, including the detailed description that follows and the appended claims.

[0009] It should be understood that the foregoing 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

[0010] The present disclosure describes various embodiments related to nanosized mesoporous zeolite compositions and methods for synthesizing these compositions.

[0011] 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.

[0012] 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 contents 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 hydrogenation 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 zeolite) in hydrocracking catalysts have an adverse effect on the performance of the catalyst. The small pore diameters prevent large molecules in the heavy oil fraction from diffusing into the active sites located inside the zeolite. 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 reducing the particle size of the zeolite catalyst, or combining these two characteristics. Disclosed herein is an ordered mesoporous zeolite composition having an average pore diameter greater than 3 nm and a particle size less than 100 nm. By increasing the external surface area of the catalyst and shortening the diffusion path of reactants and products, reducing the particle size during the synthesis of zeolite catalysts affects the performance of the zeolite catalysts.

[0013] Previous methods for synthesizing mesoporous nano-sized beta zeolites generated mesopores by desilication via NaOH or NH3 and hydrothermal treatment. However, such methods additionally require separation and washing steps after hydrothermal treatment to remove substances before calcining the zeolite. An alternative method has been developed according to the embodiments of the present disclosure for synthesizing mesoporous nano-sized beta zeolites without desilication via NaOH or NH3. This improved synthesis method increases the yield of the synthesized zeolite, reduces operating costs, does not require the solution and treatment of harmful alkaline solutions, and improves the crystallinity of the obtained zeolite.

[0014] Embodiments of BEA framework type zeolites (such as beta zeolite) are generally described in the present disclosure, and such zeolites can be incorporated into hydrotreating catalysts. The present disclosure relates to methods for producing such zeolites and the properties and structures of the produced zeolites. In some embodiments, the hydrotreating catalyst can be used to crack aromatics in heavy oil during a pretreatment process, which can be carried out before 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 beta 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 of 0.3 nm to 1 nm) can provide a large surface area and desirable size / shape selectivity, which is advantageous in catalytic applications. The described mesoporous zeolites can include, for example, aluminosilicates, titanosilicates, or pure silicates. In one or more embodiments, the described zeolites 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 currently described zeolites can be characterized as beta (i.e., having an aluminosilicate BEA framework type).

[0015] Disclosed herein are specific synthesis methods for these nanosized mesoporous zeolite compositions. According to the present disclosure, a method for synthesizing mesoporous nanosized beta zeolite prepares an aqueous cetyltrimethylammonium bromide (CTAB) solution and adds nanosized zeolite particles having a particle size less than or equal to 100 nm to the first solution to form a second solution, wherein the second solution does not include a base, and the nanosized zeolite particles include a microporous framework and a BEA framework type, and the microporous framework includes a plurality of micropores having a diameter less than or equal to 2 nm. The second solution is transferred to an autoclave operating at 25 °C to 200 °C for 3 hours to 24 hours to form a colloid. Subsequently, the colloid is washed to form a washed colloid, and the washed colloid is dried at 100 °C to 200 °C for 4 hours to 24 hours to form a zeolite precursor. Finally, the zeolite precursor is calcined at 250 °C to 600 °C for 1 hour to 8 hours to form mesoporous nanosized beta zeolite. It should be specifically noted that no base (such as NaOH or NH4OH) is added as part of the synthesis procedure for the desilication of the nanosized zeolite particles. The synthesis method of mesoporous nanosized beta zeolite and its specific steps will be discussed in detail below.

[0016] In one or more embodiments, an aqueous cetyltrimethylammonium bromide (CTAB) solution is formed. Specifically, in one or more embodiments, CTAB is mixed with water to form a substantially saturated solution. It should be noted that CTAB has a maximum water solubility of 36.4 g / L at 20 °C. Thus, as discussed in detail below, considering the mass ratio of CTAB to zeolite in the range of 0.1 to 1.0, a CTAB solution with a concentration of 7.25 g / L to 36.4 g / L can be provided.

[0017] In various embodiments, the aqueous CTAB solution can be mixed for 1 minute to 30 minutes, 5 minutes to 30 minutes, 5 minutes to 15 minutes, or approximately 10 minutes. It should be understood that the mixing time needs to be sufficient to completely dissolve CTAB in water to produce an aqueous CTAB solution.

[0018] In one or more embodiments, nano-sized zeolite particles are added to the aqueous CTAB solution to form a second solution. In various embodiments, the nano-sized zeolite particles can have an average particle size less than or equal to 100 nm, less than or equal to 90 nm, less than or equal to 85 nm, or less than or equal to 80 nm. Additionally, the nano-sized zeolite particles include the BEA framework type, such as beta zeolite. Further, the nano-sized zeolite particles include a microporous framework that includes a plurality of micropores having an average diameter less than or equal to 2 nm. However, it should be understood that the nano-sized zeolite particles can also include mesopores.

[0019] It should be understood that various nano-sized zeolite particles can be utilized, and the method of the present disclosure increases the mesoporosity of such nano-sized zeolite particles. In one or more embodiments, the nano-sized zeolite particles can include a surface area of 590 m 2 / g, a pore volume of 0.83 ml / g, an average pore diameter of 2.8 nm, and an average particle size of 80 nm, and the pore volume is divided into a micropore volume of 0.15 ml / g and a mesopore volume of 0.68 ml / g.

[0020] In various embodiments, before heating the second solution in an autoclave, after adding the nano-sized zeolite particles to the first solution, the second solution can be mixed for 1 minute to 60 minutes, 5 minutes to 40 minutes, 10 minutes to 30 minutes, or approximately 20 minutes. During the mixing of the second solution, CTAB can form micelles in the second solution, and the nano-sized zeolite particles aggregate around the micelles. When CTAB is removed during calcination, mesopores are formed in the voids left by CTAB.

[0021] In various embodiments, the mass ratio of CTAB in the second solution to the nanosized zeolite particles ranges from 0.1 to 1.0, 0.2 to 0.9, 0.3 to 0.8, 0.4 to 0.8, or is approximately 0.7. It should be understood that if insufficient CTAB is provided, CTAB cannot form micelles in the solution to enable the nanosized beta zeolite to aggregate around the micelles and subsequently form mesopores after calcination. Conversely, if an excessive amount of CTAB is provided, unnecessary costs and expenses will be incurred without increasing the benefits.

[0022] In one or more embodiments, the second solution is transferred to an autoclave for forming a colloid. It should be noted that inside the autoclave, the nanosized beta zeolite aggregates around the micelles formed by CTAB to finally form mesopores.

[0023] In various embodiments, the second solution is heated in an autoclave operating at 25°C to 200°C, 100°C to 175°C, 120°C to 160°C, 140°C to 160°C, or approximately 150°C. Additionally, in various embodiments, the second solution can be heated in the autoclave for 3 hours to 24 hours, 4 hours to 20 hours, 5 hours to 18 hours, 6 hours to 14 hours, 8 hours to 12 hours, or approximately 10 hours. In one or more embodiments, the autoclave remains stationary in the oven without rotation.

[0024] In one or more embodiments, the autoclave is quenched with water. It should be understood that quenching immediately stops any reaction in the autoclave and ensures that the reaction time for all synthesis reactions remains consistent in multiple production runs. It should also be understood that the water used for quenching the autoclave, which does not come into contact with the contents of the autoclave, need not be limited to distilled water, tap water, or purified water. In one or more embodiments, the water can be cold water, which for the purposes of this disclosure is defined as water at a temperature of 30°C or lower. In various embodiments, the autoclave can be quenched for 1 hour, 1.5 hours, 2 hours, 3 hours, or 4 hours. In a further embodiment, the autoclave can be naturally cooled to room temperature.

[0025] In one or more embodiments, the colloid produced by heating in the autoclave is washed with water to form a washed colloid. The water used for washing the zeolite precursor colloid is preferably distilled water to avoid the reaction or contamination of the resulting washed colloid. However, it should be understood that any purified water without impurities such as Mg, Na, Ca, Cl, etc. can be used, and distilled water is not required in all embodiments. These impurities, especially Mg, Ca, and Na cations, may deposit on the zeolite to neutralize the acidic sites and thus reduce the zeolite acidity and potentially reduce the zeolite stability. Washing the zeolite precursor colloid removes any free CTAB or other unwanted reaction products from the desired product.

[0026] In one or more embodiments, washing the colloid with water to form a washed colloid includes separating the solid and colloid product from the autoclave and any liquid product formed in the autoclave using a centrifuge. The solid and colloid product are then mixed with water to wash the solid and colloid product. Water can be added to the solid and colloid product at a weight ratio of the water to the product of about 10:1, and the mixture can be stirred for about 30 minutes. The resulting solution is then separated using a centrifuge. In various embodiments, the washing and separation can be repeated, with a total of 1, 2, 3, 4, or 5 washes.

[0027] In one or more embodiments, the colloid is dried to form a zeolite precursor. In various embodiments, the colloid can be dried at a high drying temperature of 100 °C to 200 °C, 100 °C to 180 °C, 100 °C to 160 °C, 110 °C to 150 °C, 100 °C to 140 °C, 100 °C to 130 °C, 100 °C to 120 °C, or 100 °C to 110 °C. Additionally, in various embodiments, the washed colloid can be dried at the high drying temperature for a period of 4 hours to 24 hours, 10 hours to 24 hours, 12 hours to 24 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.

[0028] In one or more embodiments, the zeolite precursor is calcined to form mesoporous nanosized β-zeolite. In various embodiments, the 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 about 550 °C. Additionally, in various embodiments, the 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 about 4 hours. In one or more embodiments, the heating rate during calcination is 2 °C to 4 °C per minute.

[0029] The properties of the mesoporous nanosized β-zeolite include an average particle size of 10 nm to 100 nm. This average particle size is based on SEM measurements. In some embodiments, the mesoporous nanosized β-zeolite has a particle size of 10 nm to 90 nm, 20 nm to 100 nm, 30 nm to 100 nm, 40 nm to 100 nm, or 50 nm to 100 nm. The surface area of the mesoporous nanosized β-zeolite can be 500 square meters per gram (m 2 / g) to 800 m 2 / g. In some embodiments, the surface area of the mesoporous nanosized β-zeolite can be 500 m2 from / g to 700 m 2 / g, 550 m 2 from / g to 800 m 2 / g, 550 m 2 from / g to 700 m 2 / g or 600 m 2 from / g to 700 m 2 / g. The average particle size is based on Brunauer - Emmett - Teller (BET) measurements. The pore volume of the nano - sized beta zeolite can be from 1.0 milliliters per gram (ml / g) to 2.0 ml / g. In some embodiments, the pore volume of the mesoporous nano - sized beta zeolite can be from 1.0 ml / g to 1.8 ml / g, from 1.0 ml / g to 1.6 ml / g, from 1.0 ml / g to 1.5 ml / g, or from 1.1 ml / g to 1.4 ml / g. The average pore diameter of the mesoporous nano - sized beta zeolite can be greater than 3 nm, for example, in the range of 3 nm to 50 nm. In some embodiments, the average pore diameter of the mesoporous nano - sized beta zeolite can be 2 nm to 40 nm, 5 nm to 30 nm, 5 nm to 50 nm, 5 nm to 30 nm. Alternatively, in various embodiments, the average pore diameter of the mesoporous nano - sized beta zeolite can be greater than 4 nm, greater than 5 nm, greater than 6 nm, or greater than 6.5 nm. The pore diameter can be determined by the surface area and pore volume.

[0030] Most of the pore volume of the mesoporous nano - sized beta 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 beta zeolite is mesopore.

[0031] Embodiments of the presently disclosed method for synthesizing mesoporous nano - sized beta zeolite do not require treating nano - sized zeolite particles with an alkaline solution. Eliminating this washing step increases the yield and reduces the operating cost. Specifically, since one or more steps in the traditional zeolite process are eliminated, the operating cost is reduced and the yield of the synthesized zeolite is increased, which enhances the manufacturing economy of the mesoporous nano - sized beta zeolite.

[0032] Examples

[0033] The following examples will further illustrate the method for synthesizing mesoporous nano - sized beta zeolite. The examples are illustrative in nature and should not be construed as limiting the subject matter of the present disclosure.

[0034] Samples of mesoporous nanosized beta zeolite were prepared to compare synthesis via traditional methods with synthesis according to the methods of the present disclosure. Comparative Example 2, Comparative Example 4, and Comparative Example 5 provide the synthesis of mesoporous nanosized beta zeolite using traditional methods, including dealuminating nanosized zeolite particles with at least one alkaline solution. Inventive Example 1 and Inventive Example 3 provide the synthesis of mesoporous nanosized beta zeolite, omitting all alkaline solutions.

[0035] Inventive Example 1

[0036] According to Inventive Example 1, mesoporous nanosized beta zeolite was prepared without including any alkali to assist dealumination. In a first container, 2.265 grams of CTAB from Sigma Aldrich was added to 62.5 grams of H2O, and the resulting aqueous CTAB solution was stirred for 10 minutes. The water was purified water obtained using reverse osmosis (RO) water purification technology. After mixing, 4.56 grams of nanosized beta zeolite (3.24 grams on a dry basis) was added to the aqueous CTAB solution and stirred for 20 minutes to form a second solution. The nanosized beta zeolite was the nanosized beta zeolite disclosed by L. Ding et al. in Microporous and Mesoporous Materials 94 (2006) 1 - 8. Subsequently, the second solution was transferred to a PTFE - lined stainless - steel autoclave, sealed, and heated. The autoclave was operated at 150 °C for ten hours and then quenched with water. Then the colloid formed in the autoclave was washed twice in a high - speed centrifuge. Then the solid zeolite product was dried overnight at 110 °C and calcined at 550 °C for 4 hours at a heating rate of 2 °C / minute.

[0037] Comparative Example 2

[0038] For Comparative Example 2, mesoporous nanosized beta zeolite was prepared, where NH3 was added for dealumination of the nanosized beta zeolite. In a first container, 2.265 grams of CTAB from Sigma Aldrich was added to 62.5 grams of 0.5M NH3.H2O from Sigma Aldrich, and the resulting first solution was stirred for 10 minutes. The water was purified water obtained using reverse osmosis (RO) water purification technology. After mixing, 4.56 grams of nanosized beta zeolite (3.24 grams on a dry basis) was added to the first solution and stirred for 20 minutes to form a second solution. It should be noted that the nanosized beta zeolite was the same as the nanosized beta zeolite used in Inventive Example 1. Subsequently, the second solution was transferred to a PTFE - lined stainless - steel autoclave, sealed, and heated. The autoclave was operated at 150 °C for ten hours and then quenched with water. Then the colloid formed in the autoclave was washed three times in a high - speed centrifuge. Then the solid zeolite product was dried overnight at 110 °C and calcined at 550 °C for 4 hours at a heating rate of 2 °C / minute.

[0039] The synthesis parameters of Invention Example 1 and Comparative Example 2 are provided in Table 1 below. It should be noted that the zeolite contains approximately 29% water. Therefore, when calculating the ratio of CTAB to zeolite, if the zeolite is based on dry basis, its moisture content must be considered. Specifically, 4.56 grams of zeolite includes 3.24 grams of dry basis zeolite, so the weight ratio of CTAB to zeolite is 0.7.

[0040] Table 1: Synthesis parameters of Invention Example 1 and Comparative Example 2

[0041]

[0042] Comparative Example 3

[0043] For Comparative Example 3, mesoporous nanosized β-zeolite was prepared, where NaOH was added for desilication of the nanosized β-zeolite. In a first container, 2.265 grams of CTAB from Sigma Aldrich was added to 62.5 grams of 0.5 M NaOH from Sigma Aldrich, and the resulting first solution was stirred for 10 minutes. After mixing, 4.56 grams of nanosized β-zeolite (3.24 grams on a dry basis) was added to the first solution and stirred for 20 minutes to form a second solution. It should be noted that the nanosized β-zeolite is the same as the nanosized β-zeolite used in Invention Example 1. Subsequently, the second solution was transferred to a PTFE-lined stainless steel autoclave, sealed and heated. The autoclave was operated at 150 °C for ten hours and then quenched with water. Then the colloid formed in the autoclave was washed three times in a high-speed centrifuge. Then the solid zeolite product was dried overnight at 110 °C and calcined at 550 °C for 4 hours at a heating rate of 2 °C / minute.

[0044] Comparative Example 4

[0045] For Comparative Example 4, mesoporous nanosized β-zeolite was prepared, where NaOH was added for desilication of the nanosized β-zeolite. In a first container, 2.265 grams of CTAB from Sigma Aldrich was added to 62.5 grams of 0.33 M NaOH from Sigma Aldrich, and the resulting first solution was stirred for 10 minutes. After mixing, 4.56 grams of nanosized β-zeolite (3.24 grams on a dry basis) was added to the first solution and stirred for 20 minutes to form a second solution. It should be noted that the nanosized β-zeolite is the same as the nanosized β-zeolite used in Invention Example 1. Subsequently, the second solution was transferred to a PTFE-lined stainless steel autoclave, sealed and heated. The autoclave was operated at 150 °C for ten hours and then quenched with water. Then the colloid formed in the autoclave was washed three times in a high-speed centrifuge. Then the solid zeolite product was dried overnight at 110 °C and calcined at 550 °C for 4 hours at a heating rate of 2 °C / minute.

[0046] The synthesis parameters of Invention Example 3, Comparative Example 4, and Comparative Example 5 are provided in Table 2 below.

[0047] Table 2: Synthesis Parameters of Invention Example 3 and Comparative Examples 3 and 4

[0048]

[0049] The properties of the mesoporous nano-sized β-zeolite of Invention Example 1 and Comparative Example 2 are provided in Table 3 below. Similarly, the properties of the mesoporous nano-sized β-zeolite of Invention Example 3, Comparative Example 4, and Comparative Example 5 are provided in Table 4 below. The average particle size is based on SEM measurement. The average pore diameter is determined by the surface area using the Brunauer-Emmett-Teller (BET) technique and pore volume. The XRD crystallinity is determined using CP-814E (Zeolyst International) as a reference.

[0050] Table 3: Properties of Mesoporous Nano-sized β-Zeolite

[0051]

[0052] As shown in Tables 3 and 4, the zeolites prepared by the conventional synthesis method using alkali for desilication (Comparative Example 2, Comparative Example 4, and Comparative Example 5) are similar to the zeolites prepared by the method without alkali-assisted desilication according to the present disclosure (Invention Example 1 and Invention Example 3). Specifically, by comparing Invention Example 1 with Comparative Example 2, it can be seen that even if the desilication with an alkaline solution is omitted, the desired zeolite product can still be obtained. Similarly, by comparing Invention Example 3 with Comparative Example 4 and Comparative Example 5, it can be seen that even if the desilication with an alkaline solution is omitted, the desired zeolite product can still be obtained. Therefore, it is confirmed that according to the method of the present disclosure, desilication with alkali is not required and can be omitted in the zeolite preparation process to produce mesoporous nano-sized β-zeolite according to the method of the present disclosure.

[0053] In summary, it should now be understood that various aspects of a method and system for producing aromatics and light olefins from a mixed plastic stream are disclosed herein.

[0054] According to a first aspect of the present disclosure, a method for synthesizing mesoporous nanosized beta zeolite includes: preparing an aqueous cetyltrimethylammonium bromide (CTAB) solution; adding nanosized zeolite particles having a particle size less than or equal to 100 nm to the aqueous CTAB solution to form a second solution, wherein the second solution does not include an alkali, and the nanosized zeolite particles include a microporous framework and a BEA framework type, the microporous framework including a plurality of micropores having a diameter less than or equal to 2 nm; transferring the second solution to an autoclave operating at 25 °C to 200 °C for 3 hours to 24 hours to form a colloid; washing the colloid with water to form a washed colloid; drying the washed colloid at 100 °C to 200 °C for 4 hours to 24 hours to form a zeolite precursor; and calcining the zeolite precursor at 250 °C to 600 °C for 1 hour to 8 hours to form mesoporous nanosized beta zeolite.

[0055] A second aspect includes the method according to the first aspect, wherein, based on SEM measurement, the mesoporous nanosized beta zeolite includes an average particle size of 10 nanometers to 100 nanometers.

[0056] A third aspect includes the method according to the first aspect or the second aspect, wherein, based on BET measurement, the mesoporous nanosized beta zeolite includes 500 m 2 / g to 800 m 2 / g of specific surface area.

[0057] A fourth aspect includes the method according to any one of the first aspect to the third aspect, wherein the mesoporous nanosized beta zeolite includes a pore volume of 1.0 ml / g to 2.0 ml / g.

[0058] A fifth aspect includes the method according to any one of the first aspect to the fourth aspect, wherein at least 60 volume% of the pore volume is mesopores.

[0059] A sixth aspect includes the method according to any one of the first aspect to the fifth aspect, wherein the mesoporous nanosized beta zeolite includes an average pore diameter greater than 3 nm.

[0060] A seventh aspect includes the method according to any one of the first aspect to the sixth aspect, wherein in the second solution, the mass ratio of CTAB to the nanosized zeolite particles is in the range of 0.1 to 1.0.

[0061] An eighth aspect includes the method according to any one of the first aspect to the seventh aspect, wherein before adding the nanosized zeolite particles to form the second solution, the aqueous CTAB solution is mixed for 1 minute to 30 minutes.

[0062] A ninth aspect includes the method according to any one of the first aspect to the eighth aspect, wherein before heating the second solution in the autoclave, the second solution is mixed for 1 minute to 60 minutes.

[0063] The tenth aspect includes the method according to any one of the first to ninth aspects, wherein the autoclave operates at 140°C to 160°C for 8 to 12 hours.

[0064] The eleventh aspect includes the method according to any one of the first to tenth aspects, wherein washing the colloid with water to form the washed colloid is completed in a centrifuge.

[0065] The twelfth aspect includes the method according to any one of the first to eleventh aspects, wherein the washed colloid is dried at 100°C to 120°C for 8 to 12 hours.

[0066] The thirteenth aspect includes the method according to any one of the first to twelfth aspects, wherein the zeolite precursor is calcined at 550°C to 600°C for 3 to 6 hours to form mesoporous nanosized β-zeolite.

[0067] The fourteenth aspect includes the method according to any one of the first to thirteenth aspects, wherein the heating rate during calcination is 2°C to 4°C per minute.

[0068] 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. Accordingly, 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.

[0069] Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0070] Throughout this disclosure, ranges are provided. 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 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 constitute a range of that property, and all combinations of ranges formed by all the described quantitative values of a given property are contemplated in this disclosure.

[0071] 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-limiting meaning, excluding no additional elements or steps.

[0072] 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 β-zeolite, the method comprising: Preparing an aqueous cetyltrimethylammonium bromide (CTAB) solution; Adding nanosized zeolite particles having a particle size less than or equal to 100 nm to the aqueous CTAB solution to form a second solution, wherein the second solution does not include an alkali, and the nanosized zeolite particles include a microporous framework and a BEA framework type, and the microporous framework includes a plurality of micropores having a diameter less than or equal to 2 nm; Transferring the second solution to an autoclave operating at 25 °C to 200 °C for 3 hours to 24 hours to form a colloid; Washing the colloid with water to form a washed colloid; Drying the washed colloid at 100 °C to 200 °C for 4 hours to 24 hours to form a zeolite precursor; And Calcining the zeolite precursor at 250 °C to 600 °C for 1 hour to 8 hours to form the mesoporous nanosized β-zeolite.

2. The method according to claim 1, wherein, Based on SEM measurement, the mesoporous nanosized β-zeolite includes an average particle size of 10 nanometers to 100 nanometers.

3. The method according to claim 1 or 2, wherein Based on BET measurement, the mesoporous nano-sized β zeolite has a surface area of 500 m 2 / g to 800 m 2 / g.

4. The method according to any one of claims 1 to 3, wherein the mesoporous nanosized β-zeolite includes a pore volume of 1.0 ml / g to 2.0 ml / g.

5. The method according to any one of claims 1 to 4, wherein at least 60 volume % of the pore volume is mesopores.

6. The method according to any one of claims 1 to 5, wherein the mesoporous nanosized β-zeolite includes an average pore diameter greater than 3 nm.

7. The method according to any one of claims 1 to 6, wherein in the second solution, the mass ratio of CTAB to the nanosized zeolite particles is in the range of 0.1 to 1.

0.

8. The method according to any one of claims 1 to 7, wherein before adding the nanosized zeolite particles to form the second solution, the aqueous CTAB solution is mixed for 1 minute to 30 minutes.

9. The method according to any one of claims 1 to 8, wherein before heating the second solution in the autoclave, the second solution is mixed for 1 minute to 60 minutes.

10. The method according to any one of claims 1 to 9, wherein the autoclave operates at 140 °C to 160 °C for 8 hours to 12 hours.

11. The method according to any one of claims 1 to 10, wherein washing the colloid with water to form the washed colloid is completed in a centrifuge.

12. The method according to any one of claims 1 to 11, wherein the washed colloid is dried at 100 °C to 120 °C for 8 hours to 12 hours.

13. The method according to any one of claims 1 to 12, wherein the zeolite precursor is calcined at 550 °C to 600 °C for 3 hours to 6 hours to form the mesoporous nanosized β-zeolite.

14. The method according to any one of claims 1 to 13, wherein the heating rate during calcination is 2 °C to 4 °C per minute.

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