Mordenite and method of synthesis and use thereof

Abstract

The application discloses a mordenite, a synthesis method and application thereof, and belongs to solid-state inorganic crystal materials, and the crystal structure is a mordenite structure; the crystal morphology includes spherical crystals and nanometer strip-shaped crystals. The synthesis method comprises the following steps: (1) uniformly mixing inorganic alkali, a silicon source, an aluminum source, an organic additive, a structure directing agent, an alcohol compound and water to obtain a reactant precursor; (2) loading the reactant precursor obtained in the step (1) into a reactor to perform a crystallization reaction, and then performing separation, drying and calcination to obtain the mordenite. The mordenite synthesized by the method has high crystallinity and specific morphology, and the synthesis method has good repeatability, so that the uniformity and stability of the synthesized product can be ensured.

Description

Technical Field

[0001] This invention belongs to the field of inorganic porous material synthesis, and relates to a mordenite zeolite and its synthesis method. Background Technology

[0002] Mordenite is a crystalline microporous aluminosilicate with a regularly arranged pore structure, large specific surface area, high stability, and strong acidity. It exhibits excellent catalytic performance in adsorption, separation, catalytic cracking, alkylation, disproportionation, and isomerization reactions, making it valuable for industrial applications. However, due to the one-dimensional microporous channel structure of mordenite, large molecules cannot diffuse parallel or exchange-diffused within the channels, but only in a monolayer. In catalytic reactions involving large molecules, the limited molecular diffusion rate causes molecules to clog the channels during the reaction, resulting in reduced catalytic activity and shortened catalyst lifespan, thus limiting its applications. To address this problem, current research primarily focuses on reducing the particle size of zeolite molecular sieves, i.e., synthesizing nano-sized zeolite molecular sieves, to improve the diffusion rate of molecules within the crystal.

[0003] Currently, the morphology control of mordenite zeolite in publicly available methods mainly relies on the selection of template agents. The paper "Soft Template-Guided Synthesis of Hierarchical Porous Mordenite Zeolite and its Benzylation Catalytic Performance" (Li Yuping, Journal of Inorganic Materials, December 2016, Vol. 31, No. 12) synthesized mordenite zeolite with a nanorod cluster morphology. The preparation process was as follows: sodium hydroxide, sodium aluminate, and deionized water were weighed sequentially and placed in a beaker. After dissolution and clarification, silica sol was added, and the mixture was stirred to form a homogeneous gel. The solution was placed in a constant temperature oven at 100℃ for 16 hours to obtain a molecular sieve precursor solution. After cooling, a self-made organic template agent was added, and the mixture was stirred in a water bath at 60℃ for 5 hours. The solution was then transferred to a stainless steel crystallization vessel with a polytetrafluoroethylene liner and crystallized at 160℃ for 5 days. After the reaction, the product was quenched, washed, filtered, dried, and calcined at 550℃ for 6 hours to remove the template agent, yielding a hierarchical porous mordenite zeolite molecular sieve.

[0004] CN102602958A discloses a method for preparing mesoporous mordenite zeolite, comprising the following steps: First, an aluminum source is dissolved in a sodium hydroxide solution. A silicon source is then added, and the mixture is stirred and dispersed under strong magnetic force at room temperature for a period of time. The uniformly dispersed silicon and aluminum source solutions are mixed into a gel at room temperature. A dealuminized mordenite molecular sieve is added as a seed crystal. After uniform mixing under strong magnetic force at room temperature, the mixture is transferred to a reaction crystallization vessel and crystallized at 150–170°C for 0.5–3 days. The product is then obtained after conventional filtration, washing, and drying. The prepared mordenite zeolite consists of large crystals composed of nanoribs.

[0005] CN102060308A discloses a method for synthesizing nanofiber-like mordenite. The method uses silicon source, aluminum source, inorganic acid and deionized water as reaction raw materials. By adding an appropriate amount of molecular sieve seed crystals, the mordenite is crystallized for 30-160 hours under hydrothermal conditions of autogenous pressure and crystallization temperature of 130-200℃ to synthesize highly crystalline mordenite. The synthesized mordenite has a regular c-axis elongated fibrous morphology with a width of 20-100 nanometers and a length of 1-8 micrometers. Summary of the Invention

[0006] To address the shortcomings of existing methods for synthesizing mordenite, this invention provides a mordenite, its synthesis method, and its applications. The synthesized mordenite exhibits high crystallinity and a specific morphology, and the synthesis method is highly reproducible, ensuring the uniformity and stability of the synthesized product.

[0007] The first aspect of the present invention provides a mordenite zeolite, which is a solid inorganic crystal material with a mordenite zeolite structure; its crystal morphology includes spherical crystals and nano-strip crystals.

[0008] In a further preferred embodiment, the spherical crystals in the aforementioned mordenite have a size of 1–15 μm, the first dimension of the nano-strip crystals has a size of 0.5–5 μm, and the second and third dimensions have a size of 30–100 nm.

[0009] In a further preferred embodiment, in the aforementioned mordenite, strip-shaped crystals are attached to the outer surface of spherical crystals.

[0010] In a further preferred embodiment, the mordenite mentioned above has a pore size range of less than 2 nm, classifying it as a microporous material; its total specific surface area is 300–850 m² / g. 2 / g.

[0011] In a further preferred embodiment, the main framework structural elements of the aforementioned mordenite include silicon, aluminum, and oxygen. Specifically, it is composed of silicon-oxygen structures and aluminum-oxygen structures as basic structural units, ultimately forming a network porous structure.

[0012] A second aspect of this invention provides a method for synthesizing mordenite, comprising the following steps:

[0013] (1) Inorganic base, silicon source, aluminum source, organic auxiliaries, structure directing agent, alcohol compound and water are mixed evenly to obtain reactant precursor;

[0014] (2) The reactant precursor obtained in step (1) is loaded into a reactor for crystallization reaction, and then separated, dried and calcined to obtain mordenite.

[0015] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the preparation method of the structure-directing agent in step (1) involves mixing mordenite, an inorganic alkali, and water evenly, and then treating the mixture under sealed conditions at 80–180°C for 0.5–8 hours, preferably at 100–140°C for 2–4 hours. The resulting suspension product is the structure-directing agent. The mordenite can be commercially available mordenite or synthesized according to existing methods. The inorganic alkali can be selected from one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide. More specifically, the mass ratio of mordenite, inorganic alkali, and water is 4–11:3–10:100, preferably 5–10:4–8:100. The mordenite can be a commercially available product or synthesized according to existing methods. The mordenite is a micron-scale crystal, such as spherical or bulk, with a size of 1–20 μm and a specific surface area of ​​200–600 m². 2 / g.

[0016] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the silicon source mentioned in step (1) is a solid silicon oxide with a specific surface area of ​​40–155 m². 2 / g, with concentrated mesopores, the pore size is distributed in the range of 5 to 80 nm.

[0017] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the silicon source in step (1) can be obtained by the following preparation method: mixing silica sol with water until uniform, then adding an inorganic alkali to adjust the pH value to 10-14, and then obtaining it after a first drying, calcination, washing, and a second drying.

[0018] In the above method for preparing the silicon source, the silica sol can be a common industrial product; the mass ratio of silicon oxide to water in the silica sol is 7–30:100, preferably 10–25:100. The mixing time can be 1–3 hours.

[0019] In the above-mentioned method for preparing silicon source, the inorganic base can be one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide, with sodium hydroxide being preferred.

[0020] In the above-mentioned method for preparing silicon source, the first drying temperature is 40-90℃, preferably 50-80℃.

[0021] In the above-mentioned method for preparing silicon source, the calcination temperature is 300-900℃, preferably 500-700℃; the calcination time is 1-15h, preferably 3-10h.

[0022] In the above method for preparing the silicon source, washing involves washing with deionized water until neutral.

[0023] In the above method for preparing the silicon source, the second drying temperature is 100-140℃ and the drying time is 5-15h.

[0024] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the alcohol compound mentioned in step (1) can be at least one of ethanol, propanol, and butanol.

[0025] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the aluminum source in step (1) is selected from at least one of aluminum isopropoxide, aluminum butoxide, aluminum sec-butoxide, aluminum nitrate, aluminum sulfate, aluminum chloride, and sodium aluminate, preferably at least one of aluminum isopropoxide, aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0026] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the organic auxiliary agent in step (1) is methyl orange.

[0027] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the molar ratio of inorganic alkali, silicon source (SiO2), aluminum source (Al2O3), organic auxiliaries, alcohol compounds, and water in step (1) is 2-7:15-70:1:1-6:80-220:500-1600, preferably 3-6:20-60:1:2-5:100-200:600-1500.

[0028] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the mass ratio of the structure directing agent to water in step (1) is 8-25:100, preferably 10-20:100.

[0029] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the crystallization reaction temperature in step (2) is 150-220℃, preferably 160-200℃; and the crystallization reaction time is 20-100h, preferably 30-90h.

[0030] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the separation in step (2) can be carried out by filtration, which usually includes multiple filtrations, generally 1 to 10 times.

[0031] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the drying temperature in step (2) is 80-150°C and the drying time is 1-20h.

[0032] In a further preferred embodiment, in the above-mentioned method for synthesizing mordenite, the calcination in step (2) is performed at 400–600°C for 1–10 hours. Calcination is generally carried out in the presence of air or oxygen.

[0033] The third aspect of this invention provides the application of the mordenite provided in the first aspect and / or the mordenite obtained by the preparation method described in the second aspect as a catalyst support for the carbonylation of dimethyl ether to produce methyl acetate.

[0034] The fourth aspect of the present invention provides a catalyst for the carbonylation of dimethyl ether to produce methyl acetate. The catalyst includes a support and an active metal component, wherein the active metal component is copper, and the support includes mordenite provided in the first aspect of the present invention and / or H-type mordenite obtained by the preparation method described in the second aspect after ammonium ion exchange.

[0035] Furthermore, the active metal component exists on the support in the form of oxides.

[0036] Furthermore, based on the weight of the catalyst, the copper loading as oxide is 1-10 wt%, preferably 2-8 wt%.

[0037] Furthermore, the preparation process of the catalyst for the carbonylation of dimethyl ether to produce methyl acetate first involves preparing the prepared mordenite zeolite into a hydrogen form zeolite using an ammonium ion exchange method, then loading copper metal (using copper nitrate as a precursor) using an impregnation method, and finally obtaining the catalyst through drying and calcination.

[0038] A key characteristic of zeolite materials is their regular and complex microporous channel system. These micropores provide a vast surface area, serving as the primary site for catalysis and adsorption in zeolite materials. During a catalytic reaction, reactants enter the micropores, undergo chemical reactions within the channels, and are transformed into reaction products that overflow from the channels, completing one catalytic reaction. While the microporous systems of micron-sized, three-dimensional, two-dimensional, and one-dimensional nanozeolites are essentially the same, the lengths of their micropore channels vary significantly in different directions. Therefore, the residence time of reactants in the zeolite channels of different scales varies, resulting in different degrees of reaction. Ultimately, the same reactant catalyzing a reaction on zeolites of different scales produces completely different types or compositions of reaction products. Morderne zeolite is an important catalytic material and adsorbent in the chemical industry. Its crystal morphology influences its catalytic and adsorption capabilities. Traditional micron-sized morderne zeolite has micron-level pores in all three dimensions. This invention provides a unique and abundant pore system for mordenite zeolite, possessing both conventional micron-scale and nano-scale pores. Therefore, the catalyst exhibits a more unobstructed reaction pathway, effectively addressing reactant diffusion issues during catalysis and improving catalytic efficiency. In particular, the nano-scale pores also demonstrate the advantages and uniqueness of nanoreactors in catalytic reactions.

[0039] In industrial production, product stability is paramount; only mature and reliable processes can guarantee consistent product quality. Zeolite molecular sieves are metastable substances, and their synthesis is quite challenging. Nanoscale zeolite molecular sieves, including one-dimensional, two-dimensional, and three-dimensional nanomaterials, have higher surface energies than conventional micron-scale zeolite molecular sieves, thus naturally tending to eliminate nanoscale characteristics and transition to the micron scale. Compared to conventional micron-scale zeolite synthesis methods, nanoscale zeolite synthesis methods suffer from poor stability. Some key factors controlling the size of nanomaterials may become ineffective due to factors such as raw material purity, resulting in insufficient synthesis stability of nanomaterials.

[0040] Compared with existing technologies, the synthesis method of this invention can overcome the shortcomings of poor stability in existing synthesis methods, and provides a mordenite zeolite and its synthesis method that can maintain stable product properties and have a special morphology. The specific technical effects include one or more of the following:

[0041] In the method for synthesizing mordenite provided by this invention, the crystal morphology of mordenite is controlled through the combined effects of using specially treated silicon dioxide as a silicon source, adding organic additives, and using structure-directing agents. Analysis suggests that the use of specific silicon sources and organic additives may lead to differences in the adsorption forces of different crystal faces of mordenite, selectively restricting the growth of certain crystal faces without affecting the growth of others, thus producing the mordenite with the special morphology of this invention. Comparative experimental results show that the silicon source significantly influences the crystallization process of the zeolite. When using conventional silicon sources (silica sol, silica, water glass), the crystallization product is a large, bulky crystal at the micrometer scale. Large crystals have lower surface energy and better stability than nanocrystals; therefore, conventional methods tend to synthesize large crystals rather than nanocrystals. The silicon source used in this invention behaves differently during the crystallization process compared to other silicon sources, allowing control over the crystal morphology of mordenite and yielding mordenite containing nanocrystals.

[0042] In the mordenite synthesis method provided by this invention, the use of a structure-directing agent allows for more efficient synthesis of the mordenite with its unique morphology. This is because the structure-directing agent is prepared from complete mordenite macrocrystals through alkali treatment. The main components of the structure-directing agent are mordenite fragments and primary and secondary structural units of mordenite, which can enter the pores of the silicon source and make full contact with it, thus facilitating the synthesis of mordenite. If micron-scale mordenite is used as the structure-directing agent, it cannot enter the pores of the special silicon source of this invention, significantly reducing the effectiveness of the agent.

[0043] The mordenite provided by this invention is particularly suitable as a support for the catalyst of dimethyl ether carbonylation to methyl acetate, exhibiting high reactivity and high product selectivity in the dimethyl ether carbonylation to methyl acetate reaction. Attached Figure Description

[0044] Figure 1 The image shown is a scanning electron microscope image of the sample obtained in Example 1.

[0045] Figure 2 Scanning electron microscope images of the sample obtained for Comparative Example 1.

[0046] Figure 3 The XRD pattern of the sample obtained in Example 1 is shown.

[0047] Figure 4 The XRD pattern of the sample was obtained for comparison example 1. Detailed Implementation

[0048] The technical solutions and effects of the present invention will be further illustrated below with reference to the embodiments, but the invention is not limited to the following embodiments.

[0049] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0050] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0051] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0052] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0053] In this document, all numeric values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numeric value.

[0054] The pore structure of the material of this invention was characterized by N2 adsorption-desorption using a physical adsorption instrument from Micron Technology, USA. Before measurement, the sample was vacuum-treated at 300℃ for more than 4 hours. Parameters such as total specific surface area and pore size were calculated using the BET and BJH formulas.

[0055] The phase structure and crystallinity of the material of this invention were characterized by X-ray diffraction using a Rigaku D / max2500 X-ray diffractometer (Japan), with a Cu target, Kα radiation source, graphite monochromator, tube voltage of 40kV, tube current of 80mA, scanning range of 5° to 40°, step size of 0.1°, and scanning speed of 1° / min.

[0056] The crystal morphology of the material of this invention was characterized by scanning electron microscopy using a JSM-6 301F SEM (equipped with Oxford EDS) from Nippon Electronics Corporation, with an operating voltage of 20kV, an operating distance of 15mm, and a resolution of 1.5nm.

[0057] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0058] In the context of this specification, any two or more embodiments of the present invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0059] In this document, the silicon source and structure directing agent used in the examples and comparative examples were prepared according to the following method.

[0060] Preparation of silicon source:

[0061] Silicon Source A

[0062] The silica sol was mixed with deionized water in a ratio of 20:100 (silicon oxide:water by mass = 20:100) and stirred for 2 hours. Sodium hydroxide was added to adjust the pH to 12; then the water was evaporated at 60°C. The mixture was then calcined at 600°C for 5 hours; finally, it was washed with deionized water until neutral and dried at 120°C for 12 hours to obtain the silicon source with a specific surface area of ​​130 m². 2 / g, with a pore size distribution of 5–80 nm.

[0063] Silicon source B

[0064] The silica sol was mixed with deionized water in a ratio of 10:100 (silicon oxide:water mass = 10:100) and stirred for 2 hours. Sodium hydroxide was added to adjust the pH to 11; then the water was evaporated at 50°C. The mixture was then calcined at 600°C for 5 hours; finally, it was washed with deionized water until neutral and dried at 120°C for 12 hours to obtain the silicon source with a specific surface area of ​​155 m². 2 / g, with a pore size distribution of 5–80 nm.

[0065] Silicon source C

[0066] The silica sol was mixed with deionized water at a ratio of 25:100 (silicon oxide:water by mass = 25:100) and stirred for 2 hours. Sodium hydroxide was added to adjust the pH to 13; then the water was evaporated at 80°C. The mixture was then calcined at 600°C for 5 hours; finally, it was washed with deionized water until neutral and dried at 120°C for 12 hours to obtain the silicon source with a specific surface area of ​​142 m². 2 / g, with a pore size distribution of 5–80 nm.

[0067] Preparation of structure-directing agents:

[0068] Mordant zeolite, sodium hydroxide, and deionized water were mixed in a ratio of 8:7:100 (mass ratio of mordenite: sodium hydroxide: water), stirred thoroughly, and placed in a sealed reaction vessel. The mixture was then treated in an oven at 120°C for 4 hours. The resulting suspension is the structure-directing agent. The mordenite is a commercially available product, in block form, approximately 10 μm in size, with a specific surface area of ​​420 m². 2 / g.

[0069] Example 1

[0070] Sodium hydroxide, silicon source A, aluminum chloride, methyl orange, deionized water, and structure-directing agent were mixed according to the molar ratio of inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 5:35:1:4:150:1000, and the mass ratio of structure-directing agent: water = 15:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 170℃ for 80 hours. After the reaction, the resulting solid sample was filtered multiple times, then dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated as sample A. Figure 1 and Figure 3 Analysis revealed that its crystal structure belongs to mordenite, containing two types of crystals: one is a spherical crystal of about 4 μm, and the other is a two-dimensional nano-strip crystal. The first dimension is about 1 μm in size, and the second and third dimensions are about 70 nm in size. The strip crystal is attached to the outer surface of the spherical crystal.

[0071] Example 2

[0072] Sodium hydroxide, silicon source B, aluminum chloride, methyl orange, ethanol, deionized water, and structure-directing agent were mixed according to the molar ratio of inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 3:20:1:4:100:600, and the mass ratio of structure-directing agent: water = 10:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 160℃ for 100 hours. After the reaction, the resulting solid sample was filtered several times, then dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated as B. Its crystal structure belongs to mordenite zeolite, containing two crystal morphologies: one is a spherical crystal of about 4.5 μm, and the other is a two-dimensional nano-strip crystal. The first dimension is about 1.2 μm, and the second and third dimensions are about 55 nm. The strip crystals are attached to the outer surface of the spherical crystals.

[0073] Example 3

[0074] Sodium hydroxide, silicon source C, aluminum nitrate, methyl orange, ethanol, deionized water, and structure-directing agent were added according to the following ratios: inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 6:60:1:4:200:1500, and structure-directing agent: water mass ratio = 20:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 200℃ for 30 hours. After the reaction, the resulting solid sample was filtered multiple times, then dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated C. Its crystal structure belongs to mordenite zeolite, containing two crystal morphologies: one is a spherical crystal of about 8 μm, and the other is a two-dimensional nano-strip crystal. The first dimension is about 2.5 μm, and the second and third dimensions are about 85 nm. The strip crystals are attached to the outer surface of the spherical crystals.

[0075] Example 4

[0076] Sodium hydroxide, silicon source A, aluminum chloride, methyl orange, propanol, deionized water, and structure-directing agent were mixed according to the molar ratio of inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 5.5:38:1:4:170:1100, and the mass ratio of structure-directing agent: water = 18:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 175℃ for 65 hours. After the reaction, the resulting solid sample was filtered several times, then dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated as D. Its crystal structure belongs to mordenite zeolite, containing two crystal morphologies: one is a spherical crystal of about 7.5 μm, and the other is a two-dimensional nano-strip crystal. The first dimension is about 3.5 μm, and the second and third dimensions are about 90 nm. The strip crystals are attached to the outer surface of the spherical crystals.

[0077] Example 5

[0078] Sodium hydroxide, silicon source, aluminum chloride, methyl orange, ethanol, deionized water, and structure-directing agent were mixed according to the molar ratio of inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 4.5:45:1:4:120:1350, and the mass ratio of structure-directing agent: water = 15.5:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 180℃ for 75 hours. After the reaction, the resulting solid sample was filtered several times, dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated as A. Its crystal structure belongs to mordenite zeolite, containing two crystal morphologies: one is a spherical crystal of about 1.5 μm, and the other is a two-dimensional nano-strip crystal. The first dimension is about 1.2 μm, and the second and third dimensions are about 95 nm. The strip crystals are attached to the outer surface of the spherical crystals.

[0079] Comparative Example 1

[0080] Experiments were conducted using silica as the silicon source. Sodium hydroxide, silica, aluminum chloride, methyl orange, ethanol, deionized water, and the structure-directing agent were mixed according to the following ratios: inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 5:35:1:4:150:1000, and structure-directing agent: water mass ratio = 15:100. The mixture was stirred for 2 hours. Then, it was placed in a reaction vessel and reacted at 170°C for 80 hours. After the reaction, the resulting solid sample was filtered multiple times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 400°C for 10 hours. The resulting sample was designated D1. Its crystal structure belongs to mordenite, but its crystal morphology is micron-scale bulk crystals. This indicates that the silicon source is the key factor in the morphology of the mordenite described in this invention; ordinary silicon sources cannot synthesize the mordenite with the morphology described in this invention.

[0081] Comparative Example 2

[0082] In Comparative Example 2, methyl orange was not used in the synthesis. Sodium hydroxide, silicon source A, aluminum chloride, ethanol, deionized water, and the structure-directing agent were mixed according to a molar ratio of inorganic base: silicon source: aluminum source: alcohol: water = 5:35:1:150:1000, and a mass ratio of structure-directing agent: water = 15:100. The mixture was stirred for 2 hours. Then, it was placed in a reactor and reacted at 170°C for 80 hours. After the reaction, the resulting solid sample was filtered multiple times, dried in an oven at 110°C for 12 hours, and finally calcined in air at 400°C for 10 hours. The resulting sample was designated D2. Its crystal structure belongs to mordenite, but its crystal morphology is micron-scale bulk crystals. This indicates that the organic additive of this invention is a key factor in the synthesis of the mordenite with the morphology described in this invention; without the organic additive of this invention, it is impossible to synthesize the mordenite with the morphology described in this invention.

[0083] Comparative Example 3

[0084] The synthesis experiment was conducted directly using mordenite zeolite as seed crystals. Sodium hydroxide, silicon source A, aluminum chloride, methyl orange, ethanol, deionized water, and mordenite seed crystals were mixed uniformly according to the molar ratio of inorganic base: silicon source: aluminum source: methyl orange: alcohol: water = 5:35:1:4:150:1000, and the mass ratio of seed crystals to water = 5:100. The mixture was then placed in a reaction vessel and reacted at 170℃ for 80 h. After the reaction, the resulting solid sample was filtered multiple times, dried in an oven at 110℃ for 12 h, and finally calcined in air at 400℃ for 10 h. The resulting sample was designated D3. Its crystal structure belongs to mordenite zeolite, containing two crystal morphologies: spherical crystals of approximately 5 μm and two-dimensional nano-strip crystals. The first dimension is approximately 2.5 μm, and the second and third dimensions are approximately 85 nm. The strip crystals are attached to the outer surface of the spherical crystals; however, the crystallinity is low.

[0085] Comparative Example 4

[0086] Silica sol was used directly as the silicon source without alkali treatment.

[0087] Experiments were conducted using silica sol as the silicon source. Sodium hydroxide, silica, aluminum chloride, methyl orange, deionized water, and a structure-directing agent were mixed in a molar ratio of inorganic base:silicon source:aluminum source:methyl orange:alcohol:water = 5:35:1:4:150:1000 and stirred for 2 hours. The mixture was then placed in a reactor and reacted at 170℃ for 80 hours. Afterward, the resulting solid sample was filtered multiple times, dried in an oven at 110℃ for 12 hours, and finally calcined in air at 400℃ for 10 hours. The resulting sample was designated D4. Its crystal structure is amorphous, and no mordenite was synthesized.

[0088] Table 1. Physicochemical properties of samples obtained from each example and comparative example.

[0089]

[0090]

[0091] Note: The sample obtained in Example 1 is used as a reference in this invention, and its crystallinity is set to 100%. The relative crystallinity of all other samples is obtained by comparing it with the crystallinity of the reference.

[0092] Application performance evaluation:

[0093] The materials prepared in Examples 1-5 and Comparative Examples 1-3 were used to prepare catalysts Cat1-Cat8, respectively. In the catalyst preparation process, the prepared materials were converted into hydrogen-form zeolites using an ammonium ion exchange method, and then copper metal (using copper nitrate as a precursor) was loaded using an impregnation method. Based on the weight of the catalyst, the copper loading as oxide was 5.5 wt%.

[0094] The performance of the catalyst was evaluated in a micro fixed-bed reactor. The feedstocks were dimethyl ether, CO, and H2, with a molar ratio of DME:CO:H2 = 2:5:3. The reaction pressure was 5 MPa, the reaction temperature was 200 °C, and the space velocity of the feedstock was 3000 mL / (g·h). The evaluation results are shown in Table 2. The evaluation results show that the material of this invention exhibits high reactivity and high product selectivity in the carbonylation of dimethyl ether to produce methyl acetate. The dimethyl ether conversion rate was calculated using the following formula: [1 - n(dimethyl ether concentration after reaction) / n(dimethyl ether concentration before reaction)] * 100; the ethyl acetate selectivity was calculated using the following formula: [n(ethyl acetate product concentration after reaction) / n(concentration of all products after reaction)] * 100

[0095] Table 2 Evaluation Results

[0096]

[0097]

Claims

1. A mordenite zeolite, wherein the mordenite zeolite belongs to solid inorganic crystal materials and has a mordenite zeolite structure; its crystal morphology includes spherical crystals and nano-strip crystals; the size of the spherical crystals is 1 to 15 μm, and the size of the first dimension of the nano-strip crystals is 0.5 to 5 μm, and the size of the second and third dimensions is 30 to 100 nm.

2. The mordenite according to claim 1, characterized in that: Bar-shaped crystals are attached to the outer surface of spherical crystals.

3. The mordenite according to claim 1, characterized in that: Mordenite has a pore size range of less than 2 nm, classifying it as a microporous material; its total specific surface area is 300–850 m². 2 / g.

4. A method for synthesizing mordenite, comprising the following steps: (1) An inorganic base, a silicon source, an aluminum source, an organic auxiliary agent, a structure directing agent, an alcohol compound, and water are mixed evenly to obtain a reactant precursor; the organic auxiliary agent is methyl orange; (2) The reactant precursor obtained in step (1) is loaded into a reactor for crystallization reaction, and then separated, dried and calcined to obtain mordenite.

5. The method for synthesizing mordenite according to claim 4, characterized in that: The method for preparing the structure directing agent in step (1) is to mix mordenite, inorganic alkali and water evenly, and then treat it under closed conditions at 80-180℃ for 0.5-8h, preferably at 100-140℃ for 2-4h. The resulting suspension product is the structure directing agent.

6. The method for synthesizing mordenite according to claim 4, characterized in that: The inorganic alkali is selected from one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide; the mass ratio of mordenite, inorganic alkali, and water is 4–11:3–10:100, preferably 5–10:4–8:100; the specific surface area of ​​mordenite is 200–600 m² / g. 2 / g.

7. The method for synthesizing mordenite according to claim 4, characterized in that: In step (1), the silicon source is a solid silicon oxide with a specific surface area of ​​40–155 m². 2 / g, with pore size distribution ranging from 5 to 80 nm.

8. The method for synthesizing mordenite according to claim 4, characterized in that: The silicon source mentioned in step (1) is obtained by the following preparation method: the silica sol is mixed with water evenly, and then an inorganic base is added to adjust the pH value to 10-14. Then, it is obtained after first drying, calcination, washing and second drying.

9. The method for synthesizing mordenite according to claim 8, characterized in that: The mass ratio of silicon dioxide to water in the silica sol is 7–30:100, preferably 10–25:100; the mixing time is 1–3 h; the inorganic alkali is one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide, preferably sodium hydroxide; the first drying temperature is 40–90℃, preferably 50–80℃; the calcination temperature is 300–900℃, preferably 500–700℃; and the second drying temperature is 100–140℃.

10. The method for synthesizing mordenite according to claim 4, characterized in that: In step (1), the alcohol compound is at least one of ethanol, propanol, and butanol.

11. The method for synthesizing mordenite according to claim 4, characterized in that: The aluminum source mentioned in step (1) is selected from at least one of aluminum isopropoxide, aluminum butoxide, aluminum sec-butoxide, aluminum nitrate, aluminum sulfate, aluminum chloride, and sodium aluminate, preferably at least one of aluminum isopropoxide, aluminum nitrate, aluminum sulfate, and aluminum chloride.

12. The method for synthesizing mordenite according to claim 4, characterized in that: In step (1), the molar ratio of inorganic alkali, silicon source (SiO2), aluminum source (Al2O3), organic additive, alcohol compound, and water is 2-7:15-70:1:1-6:80-220:500-1600, preferably 3-6:20-60:1:2-5:100-200:600-1500.

13. The method for synthesizing mordenite according to claim 4, characterized in that: In step (1), the mass ratio of the structure-directing agent to water is 8-25:100, preferably 10-20:

100.

14. The method for synthesizing mordenite according to claim 4, characterized in that: In step (2), the crystallization reaction temperature is 150-220℃, preferably 160-200℃; the crystallization reaction time is 20-100h, preferably 30-90h.

15. The method for synthesizing mordenite according to claim 4, characterized in that: In step (2), the drying temperature is 80-150℃ and the drying time is 1-20h.

16. The method for synthesizing mordenite according to claim 4, characterized in that: In step (2), the roasting is carried out at 400-600℃ for 1-10 hours.

17. The use of the mordenite zeolite according to any one of claims 1-3 and / or the mordenite zeolite obtained by the preparation method according to any one of claims 4-16 as a catalyst support for the carbonylation of dimethyl ether to produce methyl acetate.

18. A catalyst for the carbonylation of dimethyl ether to produce methyl acetate, the catalyst comprising a support and an active metal component, wherein the active metal component is copper, and the support comprises mordenite as described in any one of claims 1-3 and / or H-type mordenite obtained by the preparation method described in any one of claims 4-16 after ammonium ion exchange.

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