Preparation method and application of high-silicon mordenite molecular sieve

Abstract

The present application discloses a preparation method and application of a high-silicon mordenite molecular sieve, belonging to the field of industrial catalysis technology. A preparation method of a high-silicon mordenite molecular sieve comprises the following steps: S1, mixing materials containing a silicon source, an aluminum source, an alkali source, and a template agent T1, placing them in a sealed container for crystallization I, to obtain a silicon-aluminum precursor containing seed crystals; S2, mixing materials containing a silicon source, an aluminum source, a boron source, an alkali source, a template agent T2, and water, and aging them to obtain a boron-containing silicon-aluminum sol; S3, mixing materials containing the silicon-aluminum precursor and the silicon-aluminum sol, placing them in a sealed container for crystallization II, to obtain the high-silicon mordenite molecular sieve. This synthesis method is simple and low-cost, introduces boron atoms in situ, increases the silicon-aluminum ratio of the framework, avoids the collapse of lattice vacancies and partial pores in the molecular sieve framework caused by post-processing dealumination, thereby improving the catalytic activity and stability of the catalyst.

Description

Technical Field

[0001] The present application relates to a preparation method of high-silicon mordenite molecular sieve and its application, belonging to the field of industrial catalysis technology. Background Art

[0002] Mordenite is a molecular sieve with a pore structure consisting of twelve- and eight-membered rings. Since its successful artificial synthesis, it has found widespread application in chemical processes such as organic chemistry, petrochemicals, and environmental protection due to its excellent catalytic activity and hydrothermal stability. However, mordenite typically has a low silicon-to-aluminum ratio, significantly impacting its catalytic activity, reaction efficiency, and hydrothermal stability.

[0003] High silicon-aluminum ratio mordenite can usually be obtained indirectly by post-treating low silicon-aluminum ratio mordenite. The methods used mainly include acid treatment, calcination / acid treatment, high-temperature steam treatment and complex dealumination. However, these preparation methods are demanding and complex in terms of reaction conditions, which are not conducive to large-scale industrial production. In addition, the active acid sites of the obtained high-silicon mordenite are easily affected by the treatment method, thereby reducing its catalytic reaction activity. Therefore, it is particularly important to develop a method for synthesizing high-silicon mordenite molecular sieves.

[0004] Direct synthesis of high-silicon-to-aluminum ratio mordenite can be divided into template-free and template-based synthesis methods. In the template-free method, other ions are used to guide the structure, and fluoride ions are generally used to synthesize high-silicon mordenite in an amine-free system. However, the strong corrosiveness of fluoride ions makes it unsuitable for industrial scale-up production. When organic amine templates are added, a wide variety of materials are available, such as methyl violet 2-B and methyl blue pigment molecules, 1-aminomethyl-cyclohexanol, benzyltrimethylamine, diethylpiperidinium bromide, and anionic surfactants. These methods are difficult to synthesize from difficult sources, are expensive, and some are even toxic, which not only increases synthesis costs but also causes environmental pollution. Furthermore, when the silicon-to-aluminum ratio of the raw materials is high, heterocrystalline phases such as quartz, gmelinite, and analcime are easily formed, resulting in a significant difference between the silicon-to-aluminum ratio of the raw materials and the finished product, making operation difficult. Summary of the Invention

[0005] According to the first aspect of the present application, a method for preparing a high-silica mordenite molecular sieve is provided. This mordenite molecular sieve is synthesized by preparing a silica-alumina precursor, interacting with a silica-containing sol, and introducing boron into the silica-alumina sol. The resulting mordenite has a silica-alumina ratio (SiO2 / Al2O3) between 20 and 85, high crystallinity, and avoids the formation of other crystalline forms. This molecular sieve, used as a catalyst for the carbonylation of dimethyl ether to methyl acetate, exhibits superior dimethyl ether conversion and stability compared to molecular sieves synthesized by a one-step method.

[0006] A method for preparing high-silicon mordenite molecular sieve comprises the following steps:

[0007] S1, mixing materials containing silicon source, aluminum source, alkali source (M2O), and template agent T1, placing them in a sealed container for crystallization I, to obtain a silicon-aluminum precursor containing seed crystals;

[0008] S2, mixing materials containing a silicon source, an aluminum source, a boron source, an alkali source (M2O), a template agent T2, and water to obtain a boron-containing silica-alumina sol;

[0009] S3, mixing the materials containing the silicon-aluminum precursor and the silicon-aluminum sol, placing them in a sealed container for crystallization II, and obtaining the high-silicon mordenite molecular sieve.

[0010] Optionally, the silicon-aluminum ratio of the high-silicon mordenite molecular sieve is 20-85.

[0011] Optionally, the silicon-aluminum ratio of the high-silicon mordenite molecular sieve is 20-45.

[0012] Optionally, in step S1, the molar composition of the silicon-aluminum precursor is SiO2:Al2O3:M2O:H2O:T1=1:(0.01~0.05):(0.06~0.24):(1~50):(0.01~0.12).

[0013] Optionally, in step S1, the molar composition of the silicon-aluminum precursor is SiO2:Al2O3:M2O:H2O:T1=1:(0.01~0.020):(0.12~0.20):(20~45):(0.07~0.12).

[0014] Optionally, in step S1, the molar composition of the silicon-aluminum precursor is SiO2:Al2O3:M2O:H2O:T1=1:(0.025~0.03):(0.05~0.12):(15~25):(0.07~0.12).

[0015] Optionally, in step S2, the molar composition of the silica-alumina sol is SiO2:Al2O3:B2O3:M2O:H2O:T2=1:(0.01~0.05):(0.01~0.1):(0.05~0.3):(10~50):(0.01~0.30).

[0016] Optionally, in step S2, the molar composition of the silica-alumina sol is SiO2:Al2O3:B2O3:M2O:H2O:T2=1:(0.02~0.04):(0.04~0.06):(12~30):(0.12~0.25).

[0017] Optionally, in step S2, the molar composition of the silica-alumina sol is SiO2:Al2O3:B2O3:M2O:H2O:T2=1:(0.015~0.025):(0.05~0.08):(10~25):(0.12~0.22).

[0018] Optionally, in step S3, the amount of the silicon-aluminum precursor added is 1% to 10% of the mass of the silicon-aluminum sol;

[0019] The mass of the silica-alumina sol is calculated based on the mass of SiO2 in the silica-alumina sol.

[0020] Optionally, the addition amount of the silica-alumina precursor is independently selected from any value of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the silica-alumina sol or any range value between two of them.

[0021] Optionally, the silicon source is independently selected from at least one of silica sol, water glass, white carbon black, and diatomaceous earth.

[0022] Optionally, the aluminum source is independently selected from at least one of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, and aluminum sulfate.

[0023] Optionally, the alkalinity source is independently selected from at least one of alkali metal hydroxides.

[0024] Optionally, the template agent T is independently selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, tetramethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetrapropylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, triethylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, cyclohexylamine, caprolactam, hexamethyleneimine, heptamethyleneimine, cycloheptaneamine, and cyclopentaneamine.

[0025] Optionally, the boron source is selected from boric acid.

[0026] Optionally, in step S1, the conditions for crystallization I are as follows:

[0027] The temperature is 80-120℃;

[0028] The time is 4 to 12 hours.

[0029] Optionally, in step S3, the conditions for crystallization II are as follows:

[0030] The temperature is 120-200°C;

[0031] The time is 12 to 120 hours.

[0032] According to one embodiment of the present application, the method for preparing the high silicon-aluminum ratio mordenite molecular sieve comprises at least the following steps:

[0033] A silicon source, an aluminum source, an alkali source, and a template are mixed in a certain molar ratio, and then hydrothermally crystallized in a reactor under certain temperature, time, and other conditions, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, wherein the molar composition is SiO2:Al2O3:M2O:H2O:T=1:(0.025-0.05):(0.16-0.24):(1-50):(0.01-0.12);

[0034] A silicon source, an aluminum source, a boron source, an alkali source, a template and water are mixed in a certain proportion and stirred at a certain temperature to prepare a boron-containing silica-alumina sol, wherein the molar composition is SiO2:Al2O3:B2O3:M2O:H2O:T=1:(0.01-0.1):(0.01-0.1):(0.05-0.3):(10-50):(0.01-0.30);

[0035] A silicon-aluminum precursor containing seed crystals and a silicon-aluminum sol containing boron are mixed in a certain proportion to obtain a crystallized gel, wherein the amount of seed crystals added is 1 to 10% of the mass of SiO2 in the silicon-aluminum sol containing boron, and the mixture is stirred for a period of time after addition;

[0036] The uniformly mixed gel is transferred to an autoclave, reacted under certain hydrothermal crystallization conditions, and then washed and dried to obtain a high-silicon mordenite molecular sieve.

[0037] Furthermore, the silicon source can be selected from one or a mixture of two or more of silica sol, water glass, white carbon black, diatomaceous earth, etc., preferably one or a mixture of two or more of silica sol, water glass, white carbon black.

[0038] Furthermore, the aluminum source is selected from one or a mixture of two or more of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, aluminum sulfate, etc.

[0039] Furthermore, the alkali source is selected from one or a mixture of two or more alkali metal hydroxides, preferably sodium hydroxide.

[0040] Further, the template is selected from one or a mixture of two or more of cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, tetramethylammonium bromide, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetrapropylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, cetyltrimethylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, triethylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, cyclohexylamine, caprolactam, hexamethyleneimine, heptamethyleneimine, cycloheptylamine, cyclopentylamine, etc., preferably cetyltrimethylammonium bromide, tetraethylammonium bromide, triethylamine, and tetraethylammonium hydroxide.

[0041] Preferably, the crystallization conditions of the silicon-aluminum precursor containing seed crystals in step 1 are: temperature of 80-120° C. and time of 4-12 hours.

[0042] Preferably, the crystallization temperature in step 4 is 120-200° C., and the crystallization time is 12-120 hours.

[0043] According to a second aspect of the present application, an application of a high-silica mordenite molecular sieve is provided. In the method for preparing the high-silica-to-alumina ratio mordenite provided herein, a silica-alumina gel is pre-crystallized to obtain a structure-guided sol. Furthermore, a boron source is added to the silica-alumina gel, requiring only a small amount, which minimizes the impact on solution pH and product crystallinity. This allows aluminum to be concentrated on the eight-membered ring, reducing side reactions in the carbonylation reaction.

[0044] The use of the high-silicon mordenite molecular sieve obtained by the above-mentioned preparation method in the carbonylation reaction of dimethyl ether comprises the following steps:

[0045] reacting a mixture containing a dimethyl ether carbonylation catalyst and a raw material gas to obtain methyl acetate;

[0046] The raw gas includes dimethyl ether and carbon monoxide;

[0047] The dimethyl ether carbonylation catalyst is obtained by exchanging the high-silica mordenite molecular sieve with ammonium ions.

[0048] Optionally, the molar ratio of dimethyl ether to carbon monoxide is 1:1-50; the total space velocity is 1000-20000h -1 .

[0049] Optionally, the reaction conditions are as follows:

[0050] Temperature is 150-260℃;

[0051] The pressure is 1~10MPa.

[0052] Optionally, the molar ratio of dimethyl ether to carbon monoxide is 1:1-10; the total space velocity is 1000-20000h -1 .

[0053] Optionally, the reaction conditions are as follows:

[0054] Temperature is 160-220℃;

[0055] The pressure is 2~6MPa.

[0056] Optionally, the reaction temperature is independently selected from any value of 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C or any range therebetween.

[0057] According to one embodiment of the present application, a catalyst for the carbonylation of dimethyl ether to methyl acetate is provided, wherein the dimethyl ether carbonylation catalyst is obtained by exchanging ammonium ions with a mordenite molecular sieve having good low-temperature performance for the dimethyl ether carbonylation reaction prepared according to any of the methods described above.

[0058] Preferably, the ammonium ion exchange comprises the following steps:

[0059] The synthesized mordenite molecular sieve is placed in a solution containing ammonium salt to perform ion exchange, and then washed, dried and calcined to obtain the dimethyl ether carbonylation catalyst.

[0060] Preferably, the ammonium salt in the solution containing ammonium salt is at least one selected from ammonium chloride, ammonium nitrate, ammonium sulfate and the like.

[0061] Preferably, the ammonium ion concentration in the solution containing ammonium salt is 0.1 to 2 mol / L.

[0062] Preferably, the conditions for the ammonium ion exchange are: exchange time of 1 to 5 hours, exchange temperature of 50 to 90° C., liquid-to-solid mass ratio of 1 to 8:1, and exchange 2 to 4 times.

[0063] Preferably, the drying temperature is 100-140° C., and the drying time is 4-24 hours; the roasting temperature is 450-600° C., and the roasting time is 2-6 hours.

[0064] The beneficial effects of this application include:

[0065] The present application provides a method for preparing a high-silicon mordenite molecular sieve, which produces a high-silicon mordenite molecular sieve with a silicon-to-aluminum ratio (SiO2 / Al2O3) between 20 and 85. The synthesis method used is simple and low-cost. Through a special order of adding boron, boron atoms are introduced in situ to increase the silicon-to-aluminum ratio of the framework, avoid post-processing dealumination that causes lattice vacancies and partial pore collapse in the molecular sieve framework, ensure the strength of the catalyst's acidic sites, and thus improve the catalyst's catalytic activity and stability. After the addition of boron, the crystal morphology of the molecular sieve remains the same, that is, it is granular + rod-shaped before and after the addition of boron. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 The XRD spectra of Example 1, Example 2, Example 4 and Comparative Example 1 are shown.

[0067] Figure 2 These are the stability results of the dimethyl ether carbonylation catalysts prepared in Example 1, Example 3, Comparative Example 1 and Comparative Example 2.

[0068] Figure 3 These are electron microscope images of the samples of Example 3 and Comparative Example 2, where a is Example 3 and b is Comparative Example 2. DETAILED DESCRIPTION

[0069] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0070] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0071] Unless otherwise specified, conventional test methods or test methods recommended by the instrument shall be used.

[0072] The analysis method in the examples of this application is as follows:

[0073] X-ray powder diffraction (XRD) phase analysis was performed using a SmartLab SE X-ray diffractometer from Rigaku Corporation, Japan, with a Cu target, a voltage of 40 kV, and a current of 30 mA.

[0074] The elemental composition (XRF) was determined using a ZSX Primus III+ X-ray fluorescence spectrometer from Rigaku Corporation of Japan, using a 3 kW power.

[0075] The conversion of dimethyl ether and the selectivity of methyl acetate in the present application and the comparative examples are calculated based on the carbon molar number of dimethyl ether:

[0076] Dimethyl ether conversion rate = [(moles of dimethyl ether carbon in the feed gas) - (moles of dimethyl ether carbon in the product)] ÷ (moles of dimethyl ether carbon in the feed gas) × (100%);

[0077] Methyl acetate selectivity = (2 / 3) × (mole number of carbon atoms of methyl acetate in the product) ÷ [(mole number of carbon atoms of dimethyl ether in the feed gas) - (mole number of carbon atoms of dimethyl ether in the product)] × (100%).

[0078] Example 1

[0079] Using NaOH as an alkali source, sodium silicate as a silicon source, aluminum isopropoxide as an aluminum source, and hexadecyltrimethylammonium chloride as a template, a certain amount of the mixture was stirred and transferred to a reactor, maintained at 100°C for 8 hours, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, with a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:0.028:0.08:40:0.02;

[0080] Boric acid is used as the boron source, and sodium silicate, aluminum isopropoxide, tetraethylammonium hydroxide and water are composed by mole of SiO2:Al2O3:B2O3:Na2O:H2O:T=1:0.028:0.056:0.17:15:0.09, and stirred evenly to prepare boron-containing silica-alumina sol. A certain amount of silica-alumina precursor and boron-containing silica-alumina sol are mixed, and the seed crystal addition amount is 5% of the mass of SiO2 in the boron-containing silica-alumina sol. After stirring for a period of time, the temperature is raised to 170°C and maintained for 72h. The obtained sample is washed with deionized water to neutrality, dried at 120°C for 12h, and calcined at 560°C for 4h to obtain high-silicon silk zeolite molecular sieve.

[0081] Example 2

[0082] Using NaOH as an alkali source, silica sol (SiO2 mass fraction 40%) as a silicon source, aluminum sulfate as an aluminum source, and tetraethylammonium hydroxide (mass fraction 30%) as a template, a certain amount of the mixture was stirred and transferred to a reactor, maintained at 120°C for 4 hours, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, with a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:0.025:0.060:36:0.10;

[0083] Taking boric acid as the boron source, silica sol, aluminum sulfate, tetraethylammonium hydroxide and water are composed by mole of SiO2:Al2O3:B2O3:Na2O:H2O:T=1:0.025:0.050:0.12:13:0.08 and stirred evenly to prepare boron-containing silica-alumina sol. A certain amount of silica-alumina precursor and boron-containing silica-alumina sol are mixed, and the seed crystal addition amount is 5% of the mass of SiO2 in the boron-containing silica-alumina sol. After stirring for a period of time, the temperature is raised to 180°C and maintained for 36 hours. The obtained sample is washed with deionized water to neutrality, dried at 120°C for 12 hours, and calcined at 560°C for 4 hours to obtain high-silicon silk zeolite molecular sieve.

[0084] Example 3

[0085] With NaOH as the alkali source, white carbon black as the silicon source, aluminum source, and tetramethylammonium hydroxide as the template, a certain amount of the mixture was stirred and transferred to a reactor, maintained at 90°C for 2 hours, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, with a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:0.033:0.18:25:0.12;

[0086] Using boric acid as the boron source, white carbon black, aluminum hydroxide, tetramethylammonium hydroxide and water are composed of SiO2:Al2O3:B2O3:Na2O:H2O:T=1:0.033:0.06:0.17:15:0.12 by mole, and stirred evenly to prepare boron-containing silica-alumina sol. A certain amount of silica-alumina precursor and boron-containing silica-alumina sol are mixed, and the seed crystal addition amount is 7% of the mass of SiO2 in the boron-containing silica-alumina sol. After stirring for a period of time, the temperature is raised to 180℃ and maintained for 30h. The obtained sample is washed with deionized water to neutrality, dried at 120℃ for 12h, and calcined at 560℃ for 4h to obtain high-silicon mordenite molecular sieve.

[0087] Example 4

[0088] Using NaOH as the alkali source, silica sol (SiO2 mass fraction 40%) as the silicon source, sodium metaaluminate as the aluminum source, and hexadecyltrimethylammonium chloride as the template, a certain amount of the mixture was stirred and transferred to a reactor, maintained at 130°C for 6 hours, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, with a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:0.020:0.12:35:0.07;

[0089] Taking boric acid as the boron source, silica sol, sodium aluminate, hexadecyltrimethylammonium chloride and water are configured with a molar composition of SiO2:Al2O3:B2O3:Na2O:H2O:T=1:0.020:0.035:0.15:16:0.07 and stirred evenly to prepare boron-containing silica-alumina sol. A certain amount of silica-alumina precursor and boron-containing silica-alumina sol are mixed, and the seed crystal addition amount is 5% of the mass of SiO2 in the boron-containing silica-alumina sol. After stirring for a period of time, the temperature is raised to 170°C and maintained for 48 hours. The obtained sample is washed with deionized water to neutrality, dried at 120°C for 12 hours, and calcined at 560°C for 4 hours to obtain high-silicon mordenite molecular sieve.

[0090] Example 5

[0091] Using NaOH as the alkali source, sodium silicate as the silicon source, aluminum hydroxide as the aluminum source, and triethylamine as the template, a certain amount of the mixture was stirred and transferred to a reactor, maintained at 130°C for 6 hours, and then cooled to room temperature to obtain a silicon-aluminum precursor containing seed crystals, with a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:0.015:0.15:28:0.05;

[0092] Taking boric acid as the boron source, sodium silicate, aluminum hydroxide, triethylamine and water are configured in a molar ratio of SiO2:Al2O3:B2O3:Na2O:H2O:T=1:0.015:0.030:0.14:20:0.065 and stirred evenly to prepare a boron-containing silica-alumina sol. A certain amount of silica-alumina precursor and the boron-containing silica-alumina sol are mixed, and the seed crystal addition amount is 5% of the mass of SiO2 in the boron-containing silica-alumina sol. After stirring for a period of time, the temperature is raised to 180°C and maintained for 30 hours. The obtained sample is washed with deionized water to neutrality, dried at 120°C for 12 hours, and calcined at 560°C for 4 hours to obtain a high-silicon silk zeolite molecular sieve.

[0093] Comparative Example 1

[0094] Use NaOH as alkali source, silica sol (SiO2 mass fraction 40%) as silicon source, aluminum sulfate as aluminum source, tetraethylammonium hydroxide (mass fraction 30%) as template, the molar composition is SiO2:Al2O3:Na2O:H2O:T=1:0.028:0.15:15:0.10, stir evenly, transfer to a reactor after stirring, heat to 170℃ and maintain for 72h, wash the obtained sample with deionized water to neutrality, dry at 120℃ for 12h, and calcined at 560℃ for 4h to obtain a comparative example silk-screened zeolite molecular sieve.

[0095] A certain amount of the above-mentioned Na-MOR molecular sieve was weighed and placed in a beaker. Ammonium ion exchange was carried out in a 2 mol / L ammonium nitrate solution at a solid-liquid mass ratio of 1:8 at 80°C for 3 hours. After repeating the ammonium ion exchange 3 times, the mixture was dried at 120°C for 12 hours and calcined in a muffle furnace at 550°C for 4 hours to obtain an H-MOR molecular sieve catalyst.

[0096] Comparative Example 2

[0097] Step 1: Weigh a certain amount of sodium hydroxide, sodium aluminate, silica sol, and cetyltrimethylammonium bromide and mix with water, stir evenly, and then transfer to a stainless steel high-pressure hydrothermal reactor for pre-crystallization to obtain a high-silicon-aluminum ratio precursor solution with a hydroxanthenite structure. The gel composition is SiO2:Al2O3:Na2O:H2O:T=1:0.03:0.3:35:0.4. Step 2: Mix sodium hydroxide and sodium aluminate with water, then add silica sol and tetraethylammonium hydroxide, stir and age, to obtain a structure-directed sol. The gel composition is SiO2:Al2O3:Na2O:H2O:T=1:0.03:0.15:10:0.12. Step 3: The silicon-aluminum precursor solution and the structure-guided sol obtained in step 2 are mixed in a certain proportion, stirred evenly, and then transferred to a stainless steel high-pressure hydrothermal reactor for crystallization at 180°C for 24 hours. After the crystallization is completed, the product is filtered to obtain a crystallized filtrate. The product is further washed with deionized water until neutral, dried at 120°C for 12 hours, and calcined in a muffle furnace at 550°C for 4 hours to obtain Na-MOR. Step 4: Weigh a certain amount of the above-mentioned Na-MOR molecular sieve and place it in a beaker. At 80°C, 2 mol / L ammonium nitrate solution is used for ammonium ion exchange at a solid-liquid mass ratio of 1:8 for 3 hours. After repeating the ion exchange 3 times, it is dried at 120°C for 12 hours and calcined for 4 hours at a calcination temperature of 550°C to obtain an H-MOR molecular sieve catalyst.

[0098] Comparative Example 3

[0099] Step 1: Weigh a certain amount of NaOH and dissolve it in deionized water. Then, add aluminum hydroxide and boric acid to the above solution, stir evenly, transfer to a stainless steel reactor, transfer to a homogeneous reactor, and dynamically dissolve at 130°C for 5 hours. After taking out, cool to room temperature in tap water to obtain a uniform and transparent solution A; the composition ratio of each raw material in solution A is: Al2O3:B2O3:NaOH:H2O=1:2.7:32:700;

[0100] Step 2: Add 25% tetraethylammonium hydroxide solution to water, and then add JN-40 (40% SiO2) silica sol dropwise, and continue stirring for 2 hours to obtain Sol B. The composition ratio of each raw material in Sol B is SiO2:TEAOH:H2O=84:9:1200;

[0101] Sol B was dripped dropwise into solution A to form a white gel with vigorous stirring. After the titration, stirring was continued for 2 hours. The initial gel molar composition was: Al2O3:SiO2:B2O3:NaOH:TEAOH:H2O = 1:84:2.7:32:9:1900. The resulting gel was transferred to a 100 mL polytetrafluoroethylene reactor, rotated at 15 rpm, and crystallized 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 600°C for 6 hours to obtain the MOR molecular sieve.

[0102] The prepared mordenite molecular sieve catalyst sample was pressed into tablets, crushed and sieved, and 1 g of 20-40 mesh catalyst was weighed and loaded into a fixed bed reactor. It was pretreated in situ at 280 ° C for 3 hours, cooled to 180 ° C, and the reaction pressure was adjusted to 2.0 MPa for activity evaluation. The feed volume ratio DME: N2: CO was 1:13:7, and the volume space velocity was 2000 h -1 Product analysis was performed on a Fuli GC9790 gas chromatograph with an HP-PLOT / Q column and an FID detector. The dimethyl ether (DME) conversion and methyl acetate (MA) selectivity data were calculated using the area normalization method. The following results were obtained:

[0103] Table 1

[0104]

[0105] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. Application of a high-silicon mordenite molecular sieve in dimethyl ether carbonylation reaction, characterized in that: The following steps are involved: reacting a mixture containing a dimethyl ether carbonylation catalyst and a raw material gas to obtain methyl acetate; The raw gas includes dimethyl ether and carbon monoxide; The dimethyl ether carbonylation catalyst is obtained by exchanging the high-silica mordenite molecular sieve with ammonium ions; The preparation method of the high-silicon mordenite molecular sieve comprises the following steps: S1, mixing materials containing silicon source, aluminum source, alkali source, and template agent T1, placing them in a sealed container for crystallization I, to obtain a silicon-aluminum precursor containing seed crystals; S2, mixing materials containing a silicon source, an aluminum source, a boron source, an alkali source, a template agent T2, and water to obtain a boron-containing silica-alumina sol; S3, mixing the materials containing the silicon-aluminum precursor and the silicon-aluminum sol, placing them in a sealed container for crystallization II, and obtaining the high-silicon mordenite molecular sieve.

2. The use according to claim 1, characterized in that The silicon-aluminum ratio of the high-silicon mordenite molecular sieve is 20-85.

3. The use according to claim 1, characterized in that In step S1, the molar composition of the silicon-aluminum precursor is SiO2:Al2O3:M2O:H2O:T1=1:(0.01-0.05):(0.06-0.24):(1-50):(0.01-0.12).

4. The use according to claim 1, characterized in that In step S2, the molar composition of the silica-alumina sol is SiO2:Al2O3:B2O3:M2O:H2O:T2=1:(0.01-0.05):(0.01-0.1):(0.05-0.3):(10-50):(0.01-0.30).

5. The use according to claim 1, characterized in that In step S3, the amount of the silicon-aluminum precursor added is 1% to 10% of the mass of the silicon-aluminum sol; The mass of the silica-alumina sol is calculated based on the mass of SiO2 in the silica-alumina sol.

6. The use according to claim 1, characterized in that The silicon source is independently selected from at least one of silica sol, water glass, white carbon black, and diatomaceous earth.

7. The use according to claim 1, characterized in that The aluminum source is independently selected from at least one of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, and aluminum sulfate.

8. The use according to claim 1, characterized in that The alkali source is independently selected from at least one of alkali metal hydroxides.

9. The use according to claim 1, characterized in that The template agent T is independently selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium bromide, tetramethylammonium bromide, hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetrapropylammonium chloride, tetraethylammonium chloride, tetramethylammonium chloride, hexadecyltrimethylammonium hydroxide, dodecyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, triethylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, cyclohexylamine, caprolactam, hexamethyleneimine, heptamethyleneimine, cycloheptaneamine, and cyclopentaneamine.

10. The use according to claim 1, characterized in that The boron source is selected from boric acid.

11. The use according to claim 1, characterized in that In step S1, the conditions for crystallization I are as follows: The temperature is 80-120℃; The time is 4 to 12 hours.

12. The use according to claim 1, characterized in that In step S3, the conditions for crystallization II are as follows: The temperature is 120-200°C; The time is 12 to 120 hours.

13. The use according to claim 1, characterized in that The molar ratio of dimethyl ether to carbon monoxide is 1:1-50; the total space velocity is 1000-20000h -1 .

14. The use according to claim 1, characterized in that The reaction conditions are as follows: Temperature is 150-260℃; The pressure is 1~10MPa.

15. The use according to claim 1, characterized in that The molar ratio of dimethyl ether to carbon monoxide is 1:1-10; the total space velocity is 1000-20000h -1 .

16. The use according to claim 1, characterized in that The reaction conditions are as follows: Temperature is 160-220℃; The pressure is 2~6MPa.

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