Synthesis method and application of H-shaped sheet high-silicon mordenite molecular sieve

Abstract

The invention provides a synthesis method and application of an H-shaped slice high-silicon mordenite molecular sieve, and belongs to the technical field of molecular sieve synthesis and application. The preparation method comprises the following steps: mixing tetraethylammonium hydroxide and long-chain pyrrolidinium salt as template agents with an alkali source, an aluminum source and a seed crystal to form silicon-aluminum sol, aging the silicon-aluminum sol, carrying out a crystallization synthesis reaction, and carrying out ammonium ion exchange, drying and roasting to obtain the H-type high-silicon slice mordenite molecular sieve (MOR). According to the synthesized H-shaped sheet high-silicon mordenite molecular sieve, the Al element is enriched in an eight-membered ring of an MOR zeolite molecular sieve skeleton structure, acid sites which are subjected to side reactions in HMOR can be effectively shielded, and the H-shaped sheet high-silicon mordenite molecular sieve has good catalytic activity and product selectivity when being applied to a reaction for synthesizing methyl acetate through carbonylation.

Description

Technical Field

[0001] This invention relates to a method for synthesizing and applying H-type thin-sheet high-silica mordenite zeolite molecular sieves. Specifically, it relates to the preparation of H-type high-silica sheet MOR molecular sieves as catalysts for use in the carbonylation reaction of dimethyl ether or methanol to produce methyl acetate, belonging to the field of molecular sieve synthesis and application technology. Background Technology

[0002] Hydrogen-form mordenite zeolite (HMOR) possesses unique pore structures, large specific surface areas, and strong acidity, making it valuable for industrial applications in the carbonylation of dimethyl ether. Its catalytic product, methyl acetate, is widely used in the textile, fragrance, and pharmaceutical industries, serving as an important organic raw material intermediate. Literature (e.g., Angew. Chem. Int. Ed. 45(2006)1) reports that when dimethyl ether undergoes carbonylation of a methanol-dimethyl ether mixture on molecular sieves with 8-membered and 12- or 10-membered ring structures (such as MOR mordenite), the active catalytic carbonylation site is located at the Brønsted acid site of the 8-membered ring, achieving a selectivity of over 99% for methyl acetate.

[0003] Mordenite (MOR) is a one-dimensional macroporous zeolite composed of a 12-membered ring main channel, an 8-membered ring channel, and 8-membered ring side pockets connecting the two. For the dimethyl ether carbonylation reaction, the 8-membered ring provides the active site for the carbonylation reaction, while the active site of the 12-membered ring is related to the deactivation of the molecular sieve. The pore length of the molecular sieve significantly hinders the diffusion of feed and product molecules, potentially leading to: macromolecular product aggregation, increased carbon deposition rate, and rapid deactivation of the molecular sieve; and numerous secondary reactions occurring within the channels, resulting in a sharp decrease in reaction selectivity. Furthermore, the c-axis length of mordenite has a significant impact on reaction activity: while a longer c-axis is beneficial for CO enrichment and promotes the carbonylation reaction, it also makes coking and catalyst deactivation more likely.

[0004] Therefore, to address the aforementioned diffusion limitation problem, the core approach for synthesizing nanosheet-like mordenite zeolite is to shorten the diffusion path. This involves synthesizing nanoscale sheet-like molecular sieves to significantly shorten the pore length. Studies have found that crystal growth can be controlled through the synergistic effect or selective adsorption of organic template agents and structural aids, enabling the directional synthesis of sheet-like mordenite zeolite and effectively controlling its sheet thickness and interlayer spacing. The literature (J. Mater. Chem. A, 2017, 5, 8887-8891) uses long-chain monohead quaternary ammonium as a structure-directing agent to synthesize mordenite zeolite with a thickness of 20–40 nm along the c-axis. Patent CN107963637 uses hexadecyl N-dimethylethyl-N,N-dimethylammonium bromide as a template agent to synthesize sheet-like mordenite zeolite with a thickness of 40 nm along the c-axis. The literature (Angew. Chem. Int. Ed. 2020, 59, 6258-6262) synthesized a sheet-like mordenite zeolite with a thickness of only 11 nm along the b-axis using hexadecyl N-dimethylbutyl N-dimethylbenzylamine as an organic structure directing agent. Although the above methods involve the synthesis of sheet-like MOR molecular sieves, it is difficult to achieve more Al coordination at the T3 position of the 8-membered ring, making it difficult to obtain high activity and selectivity when preparing catalysts. In addition, the reagents used in these literatures are relatively complex, making it difficult to scale up industrially to achieve mass production of sheet-like MOR molecular sieves.

[0005] Both theoretical and experimental studies have confirmed that the T3 site of plate-like mordenite zeolite is the main catalytic center for DME carbonylation, exhibiting superior catalytic performance compared to traditional MOR molecular sieves in the dimethyl ether carbonylation reaction. Due to the high catalytic rate and good diffusivity of its 8-MR side-pocket acidic center, it can significantly improve the selectivity for methyl acetate; the shortened pores effectively reduce carbon deposition and product retention, thereby significantly extending the catalyst lifetime. Therefore, providing a synthetic method for plate-like high-silica mordenite zeolite molecular sieves is of great significance. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art by using long-chain pyrrolidine onium salts as organic structural aids, which work synergistically with tetraethylammonium hydroxide organic templates to synthesize high-silica sheet-like MOR zeolite molecular sieves. This enriches Al elements in the eight-membered ring of the MOR zeolite molecular sieve structure, increasing the number of Brønsted acid ions at the T3 active sites within the eight-membered ring. The prepared HMOR zeolite molecular sieve is applied to the carbonylation of dimethyl ether to synthesize methyl acetate, exhibiting high catalytic activity, good product selectivity, simple preparation process, and ease of industrial scale-up.

[0007] This invention uses TEAOH compounds as organic templates and long-chain pyrrolidine onium salts as crystallization aids, which is beneficial for the synthesis of plate-like MOR zeolite molecular sieves, improves the kinetic diffusion effect of reactant molecules, enhances reaction stability, reduces irreversible adsorption, and extends the lifespan of molecular sieve catalysts.

[0008] This invention provides a method for synthesizing H-type thin-film high-silica mordenite zeolite molecular sieves, the synthesis method comprising: (1) Mix the alkali source, tetraethylammonium hydroxide, long-chain pyrrolidine onium salt and water to form solution A; (2) Add aluminum source to solution A to form slurry, and add MOR zeolite molecular sieve seed crystals to form slurry B; (3) Add silicon source to slurry B, mix well to obtain slurry C; (4) After aging the C slurry, a crystallization synthesis reaction is carried out to obtain the crystallized product; (5) After recovering the crystallized product, ammonium ion exchange is carried out, followed by filtration, washing, drying and calcination to obtain H-type high-silica sheet-like MOR zeolite molecular sieve.

[0009] Furthermore, the long-chain pyrrolidineonium salt is selected from 1,1'-(1,5-pentadiyl)bis[1-methyl-bromopyrrolidineonium], 1-decyl-1-ethylbromopyrrolidineonium, 1-[6-(1,5-dimethyl-2-pyrrolyl)hexyl]-1,2-dimethyl-iodopyrrolidineonium, 1,1'-hexamethylenebis[1-methyl-diiodopyrrolidineonium], and 1,1'-(oxadi-2,1-ethylenediyl)bis[1-methyldiiodopyrrolidineonium] At least one of the following: 1,1'-(oxadi-2,1-ethylenediyl)bis[1-ethyl-dibromopyrrolidineonium], 1,1'-(1,4-butadiyl)bis[1-methyl-diiodopyrrolidineonium], 1,1'-(1,5-pentadiyl)bis[1-methylhydroxypyrrolidineonium], 1,1-(pentane)bis(1-methylpyrrolidineonium), and 1,1'-[1,4-phenylenebis(methylene)]bis[1-methyl-dibromopyrrolidineonium].

[0010] Furthermore, in the C slurry, the alkali source is calculated as Na2O, the silicon source as SiO2, the aluminum source as Al2O3, the tetraethylammonium hydroxide as TEA2O, and the long-chain pyrrolidine onium salt as Pyrd, and the molar ratio of each component is 0.04~0.15 Na2O:SiO2:0.02~0.08 Al2O3:0.015~0.25 TEA2O:0.01~0.25 Pyrd:15~40 H2O; the amount of MOR zeolite molecular sieve seed crystals added is 1wt%~10wt% of the mass of SiO2.

[0011] Furthermore, the amount of MOR zeolite molecular sieve seed crystals added is 1wt%~5wt% of the mass of SiO2.

[0012] Furthermore, the aging treatment temperature is 40~130℃, and the aging treatment time is 12~72 hours.

[0013] Furthermore, the aging treatment temperature is 80~120℃, and the aging treatment time is 12~48 hours.

[0014] Furthermore, the temperature of the crystallization synthesis reaction is 140~200℃, and the time of the crystallization synthesis reaction is 12~72 hours.

[0015] Furthermore, the temperature of the crystallization synthesis reaction is 180~200℃, and the time of the crystallization synthesis reaction is 12~48 hours.

[0016] Further, the slurry after the crystallization synthesis reaction is washed with water until the pH is 7-8, dried at 100-120℃ for 4-12 hours, and then calcined at 450-650℃ for 4-12 hours at a heating rate of 1-5℃ / min to obtain molecular sieve raw powder.

[0017] Further, the ammonium exchange involves exchanging calcined molecular sieve powder with a soluble ammonium salt aqueous solution at 60-90°C at a solid-liquid mass ratio of 1:(5-30) for 1-6 hours, and repeating the exchange 1-3 times. The concentration of the soluble ammonium salt aqueous solution is 0.1~1.0 mol / L, and the soluble ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride and ammonium sulfate, ammonium carbonate, ammonium bicarbonate and ammonium acetate.

[0018] Furthermore, the ammonium exchange is followed by drying and calcination. The drying temperature is 80~150℃ and the time is 2~24 hours. The calcination temperature is 450~600℃ and the time is 1~12 hours.

[0019] Furthermore, the silicon source is selected from at least one of silica sol, water glass, silica gel, type C silica gel, fumed silica, chromatography silica gel, methyl orthosilicate, and tetraethyl orthosilicate; the aluminum source is selected from at least one of sodium aluminate, sodium aluminate, aluminum hydroxide, boehmite, aluminum nitrate, aluminum chloride, aluminum powder, aluminum isopropoxide, and aluminum sulfate; and the alkali source is selected from at least one of NaOH, Na2O, Na2O2, Na2CO3, and metallic Na.

[0020] This invention provides an H-type thin-film high-silica mordenite molecular sieve prepared by the above synthesis method, wherein the Si / Al atomic molar ratio of the H-type high-silica sheet MOR zeolite molecular sieve is 30:1~5:1; and the thickness of the H-type high-silica sheet MOR zeolite molecular sieve in the c-axis direction is <200nm.

[0021] Furthermore, the Si / Al atomic molar ratio of the H-type high-silica sheet-like MOR zeolite molecular sieve is 20:1 to 7:1; the thickness of the H-type high-silica sheet-like MOR zeolite molecular sieve in the c-axis direction is ≤100nm.

[0022] This invention provides an application of the above-mentioned H-type thin-film high-silica mordenite zeolite molecular sieve in the carbonylation reaction to prepare methyl acetate, wherein methanol carbonylation reaction is carried out with methanol and carbon monoxide, or dimethyl ether carbonylation reaction is carried out with dimethyl ether and carbon monoxide.

[0023] Furthermore, methyl acetate is synthesized by reacting a feed gas containing dimethyl ether, carbon monoxide and hydrogen through a catalyst bed supported by H-type thin-film high-silica mordenite molecular sieve. The reaction temperature is 180~280℃, the reaction pressure is 0.5~6.0 MPa, and the gas hourly space velocity is 1000~6000 mL / (gcat•h). The molar ratio of dimethyl ether, carbon monoxide and hydrogen in the raw gas is 1:(4~10):(3~15), and a dry inert gas is used as the pretreatment gas.

[0024] Furthermore, the reaction temperature is 180~240℃, the reaction pressure is 2.0~5.0 MPa, and the gas hourly space velocity is 1500~4000 mL / (gcat•h).

[0025] The beneficial effects that this invention can produce include, but are not limited to, the following aspects: 1) Because one end of the long-chain pyrrolidineonium salt organic molecule is a positively charged pyrrolidineonium cation (five-membered ring) and the other end is a long alkyl chain, it has a certain degree of conformational flexibility. The long chain can be bent and folded. The synthesized plate-like MOR zeolite molecular sieve crystals are stacked in different directions, with more acidic active sites of molecular sieves, good accessibility, reduced diffusion of reactant molecules and product molecules, reduced probability of side reactions, and improved conversion efficiency.

[0026] 2) By changing the length of the alkyl chain, the size and shape of the long-chain pyrrolidine onium salt molecule can be systematically adjusted. The flexible long chain can be folded, allowing it to fill the pores of the molecular sieve more tightly. It generates effective van der Waals forces and electrostatic interactions with the silicon / aluminum species in the framework, which helps to improve the thermodynamic driving force of the synthesis process and shorten the time required for the synthesis of MOR zeolite molecular sieves.

[0027] 3) This invention can directionally regulate the acid distribution in the pores of HMOR molecules by adding organic template agents and auxiliaries, selectively reducing the concentration of acidic sites in the twelve-membered ring and increasing the concentration of acidic active sites in the eight-membered ring, thereby significantly improving the conversion rate and catalytic lifetime of HMOR-catalyzed dimethyl ether carbonylation.

[0028] 4) This invention provides a catalyst for the production of methyl acetate from dimethyl ether, which has the advantages of high space-time yield and good stability of methyl acetate, and the reaction process conditions are adjustable over a wide range, thus having a very wide range of industrial applications. Attached Figure Description

[0029] Figure 1 The image shows the XRD diffraction pattern of the MOR molecular sieve HMR-1 sample synthesized in Example 1.

[0030] Figure 2 The image shows the XRD diffraction pattern of the MOR molecular sieve HMR-2 sample synthesized in Example 2.

[0031] Figure 3 The image shows the XRD diffraction pattern of the MOR molecular sieve HMR-3 sample synthesized in Example 3.

[0032] Figure 4 The image shows the SEM morphology of the MOR molecular sieve HMR-1 sample synthesized in Example 1.

[0033] Figure 5 The image shows the SEM morphology of the MOR molecular sieve HMR-2 sample synthesized in Example 2.

[0034] Figure 6 The image shows the SEM morphology of the MOR molecular sieve HMR-3 sample synthesized in Example 3. Detailed Implementation

[0035] The embodiments and comparative examples further illustrate the implementation methods and effects of the present invention, but the scope of protection of the present invention is not limited to the contents listed in the embodiments.

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] In this embodiment, the sample was characterized by XRD using a PANalytical Xpert Pro diffractometer with Cu Kα rays (λ = 0.15406 nm), tube voltage 45 kV, tube current 40 mA, scanning range 5°~55°, step 0.026°, and each step 17.34 ms. The relative crystallinity was calculated by summing the XRD diffraction peak areas at the five highest characteristic peaks at 2θ = 9.8±0.1°, 19.6±0.1°, 22.3±0.1°, 25.7±0.1°, and 26.3°±0.1°, corresponding to the (200), (330), (150), (202), and (350) crystal planes.

[0038] The detection was performed using a Hitachi SU5000 thermal field emission scanning electron microscope in backscatter mode, with the beam current adjusted to "standard", the accelerating voltage selected as 10kV, and the magnification of 5k~50k.

[0039] In this embodiment, the in-situ infrared spectroscopy used was a Thermo Scientific Nicolet 6700. The specific procedure was as follows: degassing at 450°C under vacuum for 60 minutes, cooling to 150°C, then introducing a 10% NH3 / Ar mixture. After adsorption saturation, vacuum was applied for 30 minutes to remove gaseous and physically adsorbed ammonia molecules. The spectrum was then recorded, starting from 1540 cm⁻¹. -1 The total amount of Brønsted acid in the sample can be calculated from the peak intensity at 1540 cm⁻¹. The amount of Brønsted acid within the twelve-membered ring of the molecular sieve was characterized using pyridine adsorption-infrared spectroscopy. The specific procedure was as follows: degassing at 450℃ under vacuum for 30 min, cooling to 150℃, introducing saturated pyridine vapor, and after static adsorption saturation, evacuating under vacuum for 30 min to remove gaseous and physically adsorbed pyridine molecules. The spectrum was then recorded. -1 The amount of Brønsted acid in the twelve-membered ring can be calculated from the peak area at the peak (Applied Catalysis A: General 417-418 (2012) 236-242). Finally, the total amount of Brønsted acid is subtracted from the amount of Brønsted acid in the twelve-membered ring to obtain the amount of Brønsted acid in the eight-membered ring.

[0040] Unless otherwise specified, all raw materials used in the embodiments of this invention are purchased commercially and used directly without any special treatment. The seed crystals described in the embodiments of this invention are commercially available small-grained MOR zeolite molecular sieves synthesized without template agents. Example 1

[0041] 1) Mix 50.61g of deionized water, 1.21g of NaOH (99% purity), and 1.84g of sodium aluminate into a homogeneous solution, and stir continuously for 30 minutes. Then add 6.13g of TEAOH solution (25% purity, denoted as TEA2O) and 35.21g of 1,1'-(1,5-pentadiyl)bis[1-methyl-bromopyrrolidineonium] (99% purity, denoted as Pyrd). Subsequently, add 53.52g of silica sol (SiO2 content: 29.19wt%, Na2O content: 0.07wt%) to the aforementioned mixed solution, and add 0.31g of small-crystal MOR zeolite molecular sieve seed crystals. Stir vigorously at room temperature for 30 minutes to obtain a crystallized slurry precursor with the following molar ratio: 0.098Na2O: SiO2:0.02674Al2O3: 0.02TEA2O: 0.25Pyrd: 20H2O, the amount of seed crystals added is 2% of the total weight of SiO2 in the synthetic slurry.

[0042] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 100℃ for 12 hours, followed by dynamic crystallization at 190℃ for 18 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in a 120℃ oven for 8 hours. It was then calcined in a muffle furnace at 550℃ (3℃ / min heating) for 4 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 30.99 and a relative crystallinity of 100%.

[0043] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 0.5 mol / L ammonium nitrate solution, and ion exchange was carried out at 80℃ for 3 h at a solid-liquid mass ratio of 1:25. This process was repeated twice. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 500℃ for 4 h to obtain H-type MOR, which was labeled as HMR-1. Example 2

[0044] 1) Mix 37.67g of deionized water, 0.02g of Na2O2 (99% purity), and 1.35g of boehmite (Al2O3 content: 78wt%) into a homogeneous solution, and stir continuously for 30min. Then add 37.60g of TEAOH solution (25% purity, denoted as TEA2O) and 15.55g of 1,1-(pentane)bis(1-methylpyrrolidineonium) (99% purity, denoted as Pyrd). Subsequently, add 16.87g of water glass (SiO2 content: 29.92wt%, Na2O content: 10.76wt%) and 25.94g of silica sol (SiO2 content: 29.19wt%, Na2O content: 0.07wt%) to the aforementioned mixed solution, and add 0.25g of... Small-grained MOR zeolite molecular sieve seed crystals were stirred vigorously at room temperature for 30 min to obtain a crystallized slurry precursor with the following molar ratio: 0.143Na2O: SiO2:0.04909Al2O3: 0.152TEA2O: 0.16Pyrd: 25H2O. The amount of seed crystals added was 5% of the total weight of SiO2 in the synthesized slurry.

[0045] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 80℃ for 24 hours, followed by dynamic crystallization at 200℃ for 15 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in an oven at 105℃ for 12 hours. It was then calcined in a muffle furnace at 540℃ (3℃ / min heating) for 6 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 14.57 and a relative crystallinity of 101%.

[0046] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 1.0 mol / L ammonium chloride solution, and ion exchange was carried out at 90℃ for 3 h at a solid-liquid mass ratio of 1:10. The process was repeated once. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 550℃ for 4 h to obtain H-type MOR, which was labeled as HMR-2. Example 3

[0047] 1) Mix 50.64g deionized water, 1.75g ​​NaOH (99% purity), 1.68g Na2CO3 (99% purity), and 2.72g aluminum hydroxide (99wt% purity) into a homogeneous solution, and stir continuously for 30min. Then add 31.57g TEAOH solution (25% purity, denoted as TEA2O) and 21.78g 1-decyl-1-ethylpyrrolidone ononium (99% purity, denoted as Pyrd). Subsequently, add 21.62g silica (SiO2 content: 93.09wt%) to the aforementioned mixed solution, and add 0.60g small-crystal MOR zeolite molecular sieve seed crystals. Stir vigorously at room temperature for 30min to obtain a crystallized slurry precursor with the following molar ratio: 0.129Na2O: SiO2:0.03065Al2O3:0.08TEA2O:0.12Pyrd: 15H2O, the amount of seed crystals added is 3% of the total weight of SiO2 in the synthetic slurry.

[0048] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 120℃ for 24 hours, followed by dynamic crystallization at 180℃ for 24 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in a 110℃ oven for 12 hours. It was then calcined in a muffle furnace at 500℃ (3℃ / min heating) for 6 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 26.83 and a relative crystallinity of 103%.

[0049] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 1.5 mol / L ammonium sulfate solution, and ion exchange was carried out at 60℃ for 3 h at a solid-liquid mass ratio of 1:5. This process was repeated twice. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 520℃ for 6 h to obtain H-type MOR, which was labeled as HMR-3. Example 4

[0050] 1) Mix 86.53g of deionized water, 0.29g of NaOH (99% purity), and 1.06g of sodium aluminate (Na₂O content: 39.38wt%, Al₂O₃ content: 49.95wt%) into a homogeneous solution and stir continuously for 30 min. Then add 8.13g of TEAOH solution (25% purity, denoted as TEA₂O) and 15.69g of 1,1'-hexamethylenebis[1-methyl-diiodopyrrolidineonium] (99% purity, denoted as Pyrd). Subsequently, add 9.06g of C-type silica gel (SiO₂ content: 91.54wt%) to the aforementioned mixed solution, and add 0.17g of small-crystal MOR zeolite molecular sieve seed crystals. Stir vigorously at room temperature for 30 min to obtain a crystallized slurry precursor with the following molar ratio: 0.075Na₂O: SiO₂: 0.03764Al₂O₃: 0.05TEA2O: 0.19Pyrd: 40H2O, the amount of seed crystals added is 2% of the total weight of SiO2 in the synthetic slurry.

[0051] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 60℃ for 48 hours, followed by dynamic crystallization at 185℃ for 36 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in a 130℃ oven for 4 hours. It was then calcined in a muffle furnace at 500℃ (3℃ / min heating) for 8 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 20.67 and a relative crystallinity of 105%.

[0052] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 1.0 mol / L ammonium nitrate solution, and ion exchange was carried out at 90℃ for 2 h at a solid-liquid mass ratio of 1:10. This process was repeated 3 times. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 560℃ for 4 h to obtain H-type MOR, which was labeled as HMR-4. Example 5

[0053] 1) Mix 56.35g of deionized water, 0.44g of Na₂O (99% purity), and 0.65g of aluminum isopropoxide (99wt% purity) into a homogeneous solution, and stir continuously for 30 min. Then add 30.43g of TEAOH solution (25% purity, denoted as TEA₂O) and 4.10g of 1,1'-(oxodi-2,1-ethylenediyl)bis[1-methyldiiodopyrrolidineonium] (99% purity, denoted as Pyrd). Subsequently, add 19.37g of methyl orthosilicate (99wt% purity) to the aforementioned mixed solution, and add 0.76g of small-crystal MOR zeolite molecular sieve seed crystals. Stir vigorously at room temperature for 30 min to obtain a crystallized slurry precursor with the following molar ratio: 0.043Na₂O: SiO₂: 0.02503Al₂O₃: 0.205TEA₂O: 0.06Pyrd: 35H2O, the amount of seed crystals added is 10% of the total weight of SiO2 in the synthetic slurry.

[0054] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 130℃ for 24 hours, followed by dynamic crystallization at 190℃ for 24 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in an oven at 105℃ for 12 hours. It was then calcined in a muffle furnace at 550℃ (3℃ / min heating) for 6 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 33.26 and a relative crystallinity of 98%.

[0055] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 0.5 mol / L ammonium chloride solution, and ion exchange was carried out at 60℃ for 3 h at a solid-liquid mass ratio of 1:15. This process was repeated twice. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 550℃ for 6 h to obtain H-type MOR, which was labeled as HMR-5. Example 6

[0056] 1) Mix 41.44g of deionized water, 0.65g of NaOH (99% purity), and 1.23g of aluminum nitrate (99wt% purity) into a homogeneous solution, and stir continuously for 30min. Then add 37.23g of TEAOH solution (25% purity, denoted as TEA2O) and 1.40g of 1,1'-(1,4-butadiyl)bis[1-methyl-diiodopyrrolidineonium] (99% purity, denoted as Pyrd). Subsequently, add 27.15g of tetraethyl orthosilicate (99wt% purity) to the aforementioned mixed solution, and add 0.62g of MOR zeolite molecular sieve seed crystals. Stir vigorously at room temperature for 30min to obtain a crystallized slurry precursor with the following molar ratio: 0.062Na2O: SiO2: 0.02208Al2O3: 0.245TEA2O: 0.02Pyrd: 30H2O, the amount of seed crystals added is 8% of the total weight of SiO2 in the synthetic slurry.

[0057] 2) The gelling slurry was transferred to the inner liner of a hydrothermal crystallization autoclave and placed in a constant temperature oven for static aging at 60℃ for 24 hours, followed by dynamic crystallization at 190℃ for 20 hours. After hydrothermal crystallization, the product slurry was removed and filtered. The filter cake was repeatedly washed with deionized water and dried in a 125℃ oven for 12 hours. It was then calcined in a muffle furnace at 540℃ (3℃ / min heating) for 4 hours to obtain Na-type MOR zeolite molecular sieve with a silicon-to-aluminum ratio of nSiO2 / nAl2O3 = 39.18 and a relative crystallinity of 96%.

[0058] 3) The Na-type MOR zeolite molecular sieve sample powder was dissolved in 1.0 mol / L ammonium nitrate solution, and ion exchange was carried out at 70℃ at a solid-liquid mass ratio of 1:10 for 4 h. The process was repeated twice. The obtained NH4-type MOR was recovered by filtration, dried, and then calcined in a muffle furnace at 550℃ for 6 h to obtain H-type MOR, which was labeled as HMR-6.

[0059] Comparative Example 1 Prepared according to the method in Example 1 of patent CN114229864B: 1) Weigh 1.2g NaOH and dissolve it in 12g deionized water. Then add 0.22g aluminum hydroxide and 0.32g boric acid to the above solution. After stirring evenly, transfer it to a stainless steel reactor and then to a homogeneous reactor. Dynamically dissolve it at 130℃ for 5h. After taking it out, cool it to room temperature in tap water to obtain a homogeneous and transparent solution A. 2) Add 5g of 25% tetraethylammonium hydroxide solution to 10g of water, and add 12g of silica sol (SiO2: 40wt%) dropwise, and stir continuously for 2h to obtain sol B.

[0060] 3) Sol B was added dropwise to solution A to form a white gel, with vigorous stirring throughout the process. After titration, stirring was continued for 2 hours to age the gel. The initial molar composition of the gel was: Al2O3:SiO2:H3BO4:NaOH:TEAOH:H2O = 1:84:5.4:32:9:1900. The formed gel was transferred to a 100 mL polytetrafluoroethylene reactor and dynamically rotated at 15 rpm / min for crystallization at 150 °C for 5 days. The resulting sample was washed with deionized water until neutral, dried at 100 °C for 10 hours, and calcined at 550 °C for 6 hours to obtain a sheet-like MOR molecular sieve with a relative crystallinity of 86%, denoted as VS-1.

[0061] Comparative Example 2 Prepared according to the method in Example 1 of patent CN120136124A: 1) First, dissolve 0.51g of sodium aluminate and 0.40g of sodium hydroxide solid in 9g of deionized water. After the solution is mixed evenly, slowly add 15.75g of silica sol (30wt%) to the above solution while stirring.

[0062] 2) Continue to add 0.2g of uncalcined mordenite seed crystals and 3.4g of tetraethylammonium hydroxide (35wt%) to the mixture at one time, and then continue to stir the initial gel formed at room temperature until homogeneous.

[0063] 3) The above gel was transferred into a stainless steel reactor with a polytetrafluoroethylene liner, heated to 190°C and crystallized under dynamic conditions for 12 hours. The resulting solid product was separated by centrifugation, washed with deionized water until neutral, dried in air at 110°C, and calcined at 550°C for 4 hours to obtain the MOR molecular sieve raw powder sample.

[0064] 4) The MOR molecular sieve powder obtained in 3) was mixed with 0.5 mol / L ammonium nitrate solution at a solid-liquid ratio of 1:10, and exchanged at 80℃ for 3 hours. The exchange was repeated twice, and the mixture was calcined at 500℃ in air atmosphere for 4 hours to remove ammonia, thus obtaining hydrogen-type mordenite with a relative crystallinity of 93%, which was labeled as sample VS-2.

[0065] Table 1. Brønsted acid site content of 8-membered and 12-membered rings in the synthesized MOR molecular sieves from the examples.

[0066] As shown in Table 1, the analysis of catalyst samples VS-1 and VS-2 in Comparative Examples 1 and 2 revealed that the eight-membered ring accounted for 53%–58% of the total Brønsted acid content. In contrast, catalyst samples HMR-1–HMR-6 in Examples 1–6 used TEAOH as the organic template and long-chain pyrrolidine onium salt as the auxiliary template. During hydrothermal synthesis, due to molecular size limitations, these samples preferentially occupied the twelve-membered ring channels, making it easier for Al atoms to insert into the eight-membered ring. The eight-membered ring accounted for over 70% of the total Brønsted acid content. This process can achieve high crystallinity in a short time and control the placement of Al atoms in the eight-membered ring, enriching Al elements within the eight-membered ring and increasing the amount of Brønsted acid within it. Ultimately, this yields a catalyst more favorable for the dimethyl ether / methanol carbonylation reaction.

[0067] Examples 7-14 The catalyst samples from Examples 1-6 and the samples obtained from Comparative Examples 1-2 were prepared into catalyst particles for evaluation of the dimethyl ether carbonylation reaction: 1) A fixed-bed reactor tube with an inner diameter of 10mm and a length of 530mm is used. The reactor is 400mm long. 4g of molded catalyst (20~40 mesh) is loaded into the constant temperature section of the reactor. Quartz sand is filled above and below the catalyst.

[0068] 2) The catalyst was heated under the following programmed temperature conditions at a flow rate of 50 ml / min of N2: room temperature for 5 h → 360 °C → 6 h → 360 °C → heating stopped → purged and cooled to 230 °C.

[0069] 3) Pyridine is introduced via nitrogen gas: 230℃→3h→280℃→3h→280℃→Stop pyridine introduction. Switch to using high-purity N2 to purge excess pyridine adhering to the catalyst.

[0070] 4) The raw materials are a mixture of dimethyl ether (DME), carbon monoxide (CO), and hydrogen (H2), with a DME / CO / H2 ratio of 5 / 35 / 60 (volume ratio), a volume hourly space velocity (GHSV) of 3000 mL / (gcat•h), a reaction pressure of 2.0 MPa, and an initial reaction temperature of 200 °C. The reaction proceeds from top to bottom through the catalyst bed. The reaction is continuously run, and the results are monitored after 15 and 25 hours. The gaseous products are analyzed online using an Agilent Technologies 7890A gas chromatograph. The reactor effluent is analyzed online using a gas chromatograph equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID).

[0071] The conversion of dimethyl ether (DME) and the selectivity of methyl acetate (MA) are both calculated based on the number of carbon moles of dimethyl ether: Dimethyl ether conversion rate = [(number of carbon moles of dimethyl ether in feed gas) - (number of carbon moles of dimethyl ether in product)] ÷ (number of carbon moles of dimethyl ether in feed gas) × (100%); Selectivity of methyl acetate = (2 / 3) × (number of carbon moles of methyl acetate in the product) ÷ [(number of carbon moles of dimethyl ether in the feed gas) - (number of carbon moles of dimethyl ether in the product)] × (100%).

[0072] Table 2. Results of the H-MOR zeolite molecular sieve-catalyzed dimethyl ether carbonylation to methyl acetate synthesis in the examples and comparative examples.

[0073] As shown in Table 2, the MOR molecular sieve catalyst prepared by the method of the present invention exhibits a dimethyl ether carbonylation reaction conversion rate (TOS=50h) of over 50% and a methyl acetate selectivity >99.5%. In contrast, the catalysts VS-1 and VS-2 prepared by the comparative method show conversion rates of <35% and methyl acetate selectivity of <99% at TOS=50h, respectively. This indicates that the catalyst provided by the present invention possesses excellent catalytic activity and selectivity in the dimethyl ether carbonylation reaction to produce methyl acetate.

[0074] The MOR zeolite molecular sieve catalyst prepared by the method of the embodiments provided by the present invention exhibits a dimethyl ether carbonylation conversion rate of >45% and a methyl acetate selectivity of >99% at TOS=100 h, while the conversion rate and methyl acetate selectivity of catalysts VS-1 and VS-2 prepared by the comparative method are <31% and <97.8%, respectively, at TOS=100 h. At TOS=200 h, the dimethyl ether carbonylation conversion rate and methyl acetate selectivity are >40% and >98.6%, respectively, while the conversion rate and methyl acetate selectivity of catalysts VS-1 and VS-2 prepared by the comparative method are <30% and <97.0%, respectively, at TOS=200 h. This indicates that the catalyst provided by the present invention has good catalytic activity and deactivation resistance.

[0075] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for synthesizing H-type thin-film high-silica mordenite zeolite molecular sieves, characterized in that, The synthesis method includes: (1) Mix the alkali source, tetraethylammonium hydroxide, long-chain pyrrolidine onium salt and water to form solution A; (2) Add aluminum source to solution A to form slurry, and add MOR zeolite molecular sieve seed crystals to form slurry B; (3) Add silicon source to slurry B, mix well to obtain slurry C; (4) After aging the C slurry, a crystallization synthesis reaction is carried out to obtain the crystallized product; (5) After recovering the crystallized product, ammonium ion exchange is carried out, followed by filtration, washing, drying and calcination to obtain H-type high silica sheet MOR zeolite molecular sieve.

2. The synthesis method according to claim 1, characterized in that, The long-chain pyrrolidine ononium salt is selected from 1,1'-(1,5-pentadiyl)bis[1-methyl-bromopyrrolidine ononium], 1-decyl-1-ethylbromopyrrolidine ononium, 1-[6-(1,5-dimethyl-2-pyrrolyl)hexyl]-1,2-dimethyl-iodopyrrolidine ononium, 1,1'-hexamethylenebis[1-methyl-diiodopyrrolidine ononium], 1,1'-(oxadi-2,1-ethylenediyl)bis[1-methyldiiodopyrrolidine ononium], 1 At least one of 1'-(oxadi-2,1-ethylenediyl)bis[1-ethyl-dibromopyrrolidineonium], 1,1'-(1,4-butadiyl)bis[1-methyl-diiodopyrrolidineonium], 1,1'-(1,5-pentadiyl)bis[1-methylhydroxypyrrolidineonium], 1,1-(pentane)bis(1-methylpyrrolidineonium), and 1,1'-[1,4-phenylenebis(methylene)]bis[1-methyl-dibromopyrrolidineonium].

3. The synthesis method according to claim 1 or 2, characterized in that, In the C slurry, the alkali source is calculated as Na2O, the silicon source as SiO2, the aluminum source as Al2O3, the tetraethylammonium hydroxide as TEA2O, and the long-chain pyrrolidine onium salt as Pyrd. The molar ratio of each component is 0.04~0.15 Na2O:SiO2:0.02~0.08 Al2O3:0.015~0.25 TEA2O:0.01~0.25 Pyrd:15~40 H2O. The amount of MOR zeolite molecular sieve seed crystals added is 1wt%~10wt% of the mass of SiO2, preferably 1wt%~5wt%.

4. The synthesis method according to any one of claims 1 to 3, characterized in that, The aging process is carried out at a temperature of 40~130℃, preferably 80~120℃, and the aging process is carried out for a time of 12~72 hours, preferably 12~48 hours. And / or, the temperature of the crystallization synthesis reaction is 140~200℃, preferably 180~200℃, and the time of the crystallization synthesis reaction is 12~72 hours, preferably 12~48 hours; And / or, the slurry after the crystallization synthesis reaction is washed with water until the pH is 7-8, dried at 100-120℃ for 4-12 hours, and then calcined at 450-650℃ for 4-12 hours at a heating rate of 1-5℃ / min to obtain molecular sieve raw powder.

5. The synthesis method according to any one of claims 1 to 4, characterized in that, The ammonium exchange involves exchanging calcined molecular sieve powder with a soluble ammonium salt aqueous solution at 60-90°C at a solid-liquid mass ratio of 1:(5-30) for 1-6 hours, and repeating the exchange 1-3 times. The concentration of the soluble ammonium salt aqueous solution is 0.1~1.0 mol / L, and the soluble ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride and ammonium sulfate, ammonium carbonate, ammonium bicarbonate and ammonium acetate.

6. The synthesis method according to any one of claims 1 to 5, characterized in that, After ammonium exchange, the mixture is dried and calcined. The drying temperature is 80~150℃ and the time is 2~24 hours. The calcination temperature is 450~600℃ and the time is 1~12 hours.

7. The synthesis method according to any one of claims 1 to 6, characterized in that, The silicon source is selected from at least one of silica sol, water glass, silica gel, type C silica gel, fumed silica, chromatography silica gel, methyl orthosilicate, and tetraethyl orthosilicate; the aluminum source is selected from at least one of sodium aluminate, sodium aluminate, aluminum hydroxide, boehmite, aluminum nitrate, aluminum chloride, aluminum powder, aluminum isopropoxide, and aluminum sulfate; the alkali source is selected from at least one of NaOH, Na2O, Na2O2, Na2CO3, and metallic Na.

8. An H-type thin-film high-silica mordenite zeolite molecular sieve prepared by the synthesis method according to any one of claims 1 to 7, characterized in that, The Si / Al atomic molar ratio of the H-type high-silica sheet-like MOR zeolite molecular sieve is 30:1~5:1, preferably 20:1~7:1; the thickness of the H-type high-silica sheet-like MOR zeolite molecular sieve in the c-axis direction is <200nm, preferably ≤100nm.

9. The application of the H-type thin-film high-silica mordenite zeolite molecular sieve of claim 8 in the carbonylation reaction to prepare methyl acetate, characterized in that: Methanol carbonylation can be carried out using methanol and carbon monoxide, or dimethyl ether carbonylation can be carried out using dimethyl ether and carbon monoxide.

10. The application according to claim 9, characterized in that, Methyl acetate is synthesized by reacting a feed gas containing dimethyl ether, carbon monoxide, and hydrogen through a catalyst bed supported on H-type thin-film high-silica mordenite molecular sieve. The reaction temperature is 180~280℃, preferably 180~240℃, the reaction pressure is 0.5~6.0 MPa, preferably 2.0~5.0 MPa, and the gas hourly space velocity is 1000~6000 mL / (gcat•h), preferably 1500~4000 mL / (gcat•h). The molar ratio of dimethyl ether, carbon monoxide and hydrogen in the raw gas is 1:(4~10):(3~15), and a dry inert gas is used as the pretreatment gas.

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