A preparation method and application of molecular sieve catalyst

Abstract

The present invention is a preparation method and application of a molecular sieve catalyst. The method comprises the following steps: (1) placing the formed molecular sieve in a molecular sieve original powder crystallization liquid, crystallizing, filtering, washing and drying to obtain an intermediate product; (2) exchanging H ions and roasting the intermediate product to obtain the molecular sieve catalyst. The molecular sieve catalyst is used for the carbonylation reaction of dimethyl ether and carbon monoxide. The molecular sieve catalyst exhibits higher performance and less by-products. The present invention has the advantages of simple preparation process, high raw material utilization rate, etc., and has good industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a preparation method and application of a molecular sieve catalyst. Background Art

[0002] With the growing demand for energy and the intensification of the contradiction between tight oil supply and the increasing global environmental pressure, fuel ethanol has attracted widespread attention from countries around the world for its cleanliness and environmental protection. As an important clean energy, ethanol can be mixed with gasoline at a ratio of 10%. Fuel ethanol gasoline can reduce the emission of carbon monoxide and hydrocarbons in automobile exhaust, which is of great significance to solving the problem of air pollution and achieving sustainable development in my country.

[0003] At present, fuel ethanol is mainly divided into three categories: grain ethanol, non-grain ethanol and cellulosic ethanol. Grain ethanol uses corn, wheat and other grains as raw materials. Since the production of grain ethanol and non-grain ethanol will occupy more arable land and there is a problem of competing for food with people and livestock, it is gradually being restricted or banned by relevant policies of various governments. In recent years, domestic and foreign researchers have explored an economical, environmentally friendly and green process route of "synthesis gas → methanol → dimethyl ether → methyl acetate → ethanol".

[0004] At present, China has developed a technical route of "dimethyl ether → methyl acetate → ethanol", and a carbonylation reaction between dimethyl ether and carbon monoxide to produce methyl acetate, and a hydrogenation reaction between methyl acetate and hydrogen to produce ethanol. Among them, the technology of hydrogenating methyl acetate to ethanol has long been mature and has been applied in industrial applications.

[0005] Patent CN104338553A uses microwave acid-base treatment of ZSM-35 molecular sieve to improve the activity and stability of dimethyl ether carbonylation reaction. Patent CN101613274A uses pyridine and other organic amines to modify the mordenite molecular sieve catalyst, and the selectivity of methyl acetate is greater than 99%, and the stability of the catalyst life is greatly improved to more than 50 hours. Patent CN103896766A increases the one-way life of the mordenite catalyst to more than 1000 hours by adding pyridine and other organic amines to the feed. This pyridine modification method can well solve the problem of short life of the mordenite catalyst. Patent CN106311336A uses methyl or acetyl organic matter to selectively modify the pores of the mordenite molecular sieve, and the one-way life of the dimethyl ether carbonylation reaction catalyst is increased to more than 600 hours. Industrial catalysts require a certain strength, and a certain amount of binder will be added during the molding process to increase its strength. The binder in the catalyst is inert during the reaction or has some adverse effects on the reaction, and the effect becomes greater as the amount of binder increases. Summary of the invention

[0006] The present invention aims at the deficiencies of the prior art and provides a method for preparing a molecular sieve catalyst. The present invention reduces the binder content of the formed molecular sieve by crystallization, increases the content of the molecular sieve, and thus improves the catalytic performance of the molecular sieve catalyst.

[0007] Another object of the present invention is to provide an application of the molecular sieve catalyst described above, wherein the molecular sieve catalyst is used for the carbonylation reaction of dimethyl ether and carbon monoxide with a high conversion rate.

[0008] To achieve the purpose of the present invention, the present invention adopts the following technical solution:

[0009] A method for preparing a molecular sieve catalyst, the method comprising the following steps:

[0010] (1) placing the formed molecular sieve in a crystallization solution, and obtaining an intermediate product through crystallization, filtration, washing and drying; (2) subjecting the intermediate product to H ion exchange and calcination to obtain the molecular sieve catalyst.

[0011] As a better embodiment of the present application, the molded molecular sieve refers to the molding of Na-MOR, Na-ZSM-35 or Na-FER raw powder and a binder, and the molding methods include ball molding and extrusion molding. The ball size is 3-5mm, the extrusion diameter is 2-5mm, and the length is 3-5mm; the binder is one or a combination of silica sol or SB powder.

[0012] Furthermore, the Si / Al ratio of the raw powder of Na-MOR, Na-ZSM-35 or Na-FER molecular sieve is 5-50, and the mass ratio of the raw powder to the binder is 1:0.1-1.0.

[0013] As a better embodiment of the present application, the crystallization liquid is composed of a certain proportion of H2O, NaOH, ammonium salt, silicon material or aluminum material, and the mass ratio is 100:0.01-10.0:0.01-2.0:0.01-10.0. After molding, the ratio of the molecular sieve to the crystallization liquid is 1kg:(4-20)L.

[0014] In step (1), the specific steps of adding the crystallization liquid to the formed molecular sieve are: mixing water, NaOH, ammonium salt and the formed molecular sieve, then heating to 85±5°C, and stirring at a stirring rate of 50-100r / min for 5±1 hours and then slowly adding silicon material or aluminum material; after all the materials are added, crystallization treatment is performed.

[0015] As a better embodiment of the present application, the ammonium salt used in the crystallization solution includes any one or more combinations of hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride, etc.

[0016] As a better implementation in the present application, the silicon material used in the crystallization solution is one or more combinations of silica sol, silicon powder or white carbon black, etc.; the aluminum material is one or more combinations of aluminum chloride, aluminum sulfate, aluminum nitrate, sodium aluminate.

[0017] As a preferred embodiment of the present application, the crystallization temperature in step (1) is 130-200°C, the time is 12-120h, and the stirring rate is 100-500r / min.

[0018] As a better implementation in the present application, the pH value of the filtrate after washing in step (1) is less than 9, the drying temperature is 100-130° C., and the drying time is 1-20 h.

[0019] As a better embodiment of the present application, the intermediate product in step (2) is exchanged with a solution of ammonium salt and water in a mass ratio of 1:(0.2-2.0):(5-20), the exchange temperature is 60-90°C, and the exchange time is 2-10h.

[0020] As a preferred embodiment of the present application, the ammonium salt used for H ion exchange includes any one or more combinations of ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium carbonate.

[0021] As a preferred embodiment of the present application, the calcination temperature in step (2) is 500-600° C., and the calcination time is 2-10 h.

[0022] The molecular sieve catalyst obtained by the above method is preferably used in the carbonylation reaction of dimethyl ether and carbon monoxide.

[0023] Furthermore, dimethyl ether and carbon monoxide are used as raw materials, and methyl acetate is obtained by reacting in a reactor filled with a molecular sieve catalyst, the reaction temperature is 150-210°C, the reaction pressure is 1.0-10.0 MPa, and the raw material gas space velocity is 1000-10000h -1 The volume ratio of carbon monoxide to dimethyl ether in the raw gas is 5:1 to 20:1.

[0024] Preferably, before the reaction, the catalyst is pre-adsorbed with pyridine or methyl iodide at a temperature of 250-350° C. and a pyridine or methyl iodide concentration of 0.1-10.0 v.%.

[0025] Compared with the prior art, the positive effects of the present invention are embodied in:

[0026] (i) After forming, the binder that occupies a certain mass in the molecular sieve does not have any catalytic activity, but may change the acid strength of the catalyst, resulting in a decrease in the selectivity of the reaction product. The present invention reduces the binder content of the molecular sieve after forming by crystallization, thereby increasing the content of the molecular sieve and improving the catalytic performance of the molecular sieve catalyst.

[0027] (ii) The molecular sieve catalyst preparation method is simple to operate, repeatable, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 XRD diagram of samples 3# and 6# in the embodiment

[0029] Figure 2 The XRD diagram of samples 2# and 5# in the embodiment is shown in FIG.

[0030] Figure 3 XRD diagrams of samples 1# and 4# in the embodiment DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] In the examples, the pyridine-treated molecular sieve catalyst was prepared according to the method disclosed in CN103896766A, and the iodomethane-treated molecular sieve catalyst was prepared according to the method disclosed in CN106311336A.

[0033] Example 1

[0034] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0035] Step (1): Use Na-MOR (Si / Al molar ratio = 10) molecular sieve powder and silica sol binder (commercially available) to roll ball forming, the ball diameter is 3-3.3mm, the mass ratio of molecular sieve powder and silica sol binder is 1:0.2, and the formed molecular sieve is obtained. The crystallization liquid is composed of H2O, NaOH, dodecyltrimethylammonium chloride, and aluminum chloride, and the mass ratio of these substances is 100:0.05:0.02:0.1. The specific steps of adding the crystallization liquid to the formed molecular sieve are: first mix H2O, NaOH, dodecyltrimethylammonium chloride and the formed molecular sieve, then heat to 85°C, and stir for 5 hours under the condition of stirring speed of 60r / min, and then slowly add aluminum chloride; the formed molecular sieve and the crystallization liquid are crystallized in a ratio of 1kg:10L. The crystallization temperature is 165°C, the time is 24h, and the stirring speed is 200r / min. The pH value of the washing filtrate is less than 9, the drying temperature is 110°C, the drying time is 5 hours, and an intermediate product is obtained.

[0036] Step (2): The intermediate product is subjected to H ion exchange; the mass ratio of the intermediate product, ammonium nitrate and water is 1:0.5:10, the exchange temperature is 75°C, and the exchange time is 4h. The exchanged material is roasted at a temperature of 550°C and a roasting time of 4h to obtain molecular sieve catalyst 1#.

[0037] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0038] Weigh 20g of molecular sieve catalyst 1# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 165℃. Stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0039] Example 2

[0040] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0041] Step (1): Na-MOR (Si / Al ratio 12) molecular sieve raw powder and silica sol binder are used for ball forming, the ball diameter is 3-3.3mm, the mass ratio of each substance is 1:0.3, and the formed molecular sieve is obtained. The crystallization liquid is composed of H2O, NaOH, tetradecyltrimethylammonium chloride, and aluminum nitrate, and the mass ratio of these substances is 100:0.05:0.02:0.4. The specific steps of adding the crystallization liquid to the formed molecular sieve are: firstly mix H2O, NaOH, tetradecyltrimethylammonium chloride and the formed molecular sieve, and then heat to 86°C, and stir for 5.5 hours under the condition of stirring speed of 70r / min, and then slowly add aluminum nitrate, and the formed molecular sieve and the crystallization liquid are crystallized in a ratio of 1kg:10L. The crystallization temperature is 165°C, the time is 24h, and the stirring speed is 200r / min. The pH value of the washing filtrate is less than 9, the drying temperature is 110°C, and the drying time is 5h to obtain the intermediate product.

[0042] Step (2): The intermediate product is subjected to H ion exchange; the mass ratio of the intermediate product, ammonium nitrate and water is 1:0.5:10, the exchange temperature is 75°C, and the exchange time is 4h. The exchanged material is roasted at a temperature of 550°C and a roasting time of 4h to obtain molecular sieve catalyst 2#.

[0043] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0044] Weigh 20g of molecular sieve catalyst 2# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 165°C. Stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0045] Example 3

[0046] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0047] Step (1): using Na-MOR (Si / Al ratio 15) molecular sieve raw powder and SB powder binder to roll ball forming, the ball diameter is 3-3.3mm, the mass ratio of each substance is 1:0.6, and the formed molecular sieve is obtained. The crystallization liquid is composed of H2O, NaOH, tetradecyl trimethyl ammonium chloride, and silica sol, and the mass ratio of these substances is 100:0.05:0.02:5.5. The specific steps of adding the crystallization liquid to the formed molecular sieve are: mixing H2O, NaOH, tetradecyl trimethyl ammonium chloride with the formed molecular sieve, and then heating to 85°C, and stirring at a stirring rate of 80r / min, stirring for 4.5 hours and then slowly adding silica sol; the formed molecular sieve and the crystallization liquid are crystallized at a ratio of 1kg:10L. The crystallization temperature is 170°C, the time is 24h, and the stirring rate is 200r / min. The pH value of the washing filtrate is less than 9, the drying temperature is 110°C, and the drying time is 5h to obtain an intermediate product.

[0048] Step (2): The intermediate product is subjected to H ion exchange; the mass ratio of the intermediate product, ammonium nitrate and water is 1:0.6:10, the exchange temperature is 80°C, and the exchange time is 4h. The exchanged material is roasted at a temperature of 550°C and a roasting time of 4h to obtain molecular sieve catalyst 3#.

[0049] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0050] (3) Weigh 20 g of molecular sieve catalyst 3# for activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load into a stainless steel reaction tube with an inner diameter of 43 mm, then slowly increase the pressure to 2.0 MPa with N2 gas and control the reaction temperature to 175°C. Stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000 h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0051] Comparative Example 1

[0052] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0053] Step (1): using Na-MOR (Si / Al ratio 10) molecular sieve raw powder and silica sol binder to roll ball forming, the ball diameter is 3-3.3mm, the mass ratio of each material is 1:0.2, and the formed molecular sieve is obtained.

[0054] Step (2): After molding, the mass ratio of molecular sieve, ammonium nitrate and water is 1:0.5:10, the exchange temperature is 75°C, the exchange time is 4h, the roasting temperature is 550°C, the roasting time is 4h, and the molecular sieve catalyst 4# is obtained.

[0055] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0056] Weigh 20g of molecular sieve catalyst 4# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 165℃, stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0057] Comparative Example 2

[0058] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0059] Step (1): using Na-MOR (Si / Al ratio 12) molecular sieve raw powder and silica sol binder to form balls, the ball diameter is 3-3.3 mm, the mass ratio of each substance is 1:0.3, and the formed molecular sieve is obtained.

[0060] Step (2): After molding, the mass ratio of molecular sieve, ammonium nitrate and water is 1:0.5:10, the exchange temperature is 75°C, the exchange time is 4h, the roasting temperature is 550°C, the roasting time is 4h, and the molecular sieve catalyst 5# is obtained.

[0061] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0062] (3) Weigh 20 g of molecular sieve catalyst 5# for activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load into a stainless steel reaction tube with an inner diameter of 43 mm, then slowly increase the pressure to 2.0 MPa with N2 gas and control the reaction temperature to 165°C. Stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000 h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0063] Comparative Example 3

[0064] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0065] Step (1): using Na-MOR (Si / Al ratio 15) molecular sieve raw powder and SB powder binder to form balls, the ball diameter is 3-3.3 mm, the mass ratio of each substance is 1:0.6, and the formed molecular sieve is obtained.

[0066] Step (2): After molding, the mass ratio of molecular sieve, ammonium nitrate and water is 1:0.6:10, the exchange temperature is 80°C, the exchange time is 4h, the roasting temperature is 550°C, the roasting time is 4h, and the molecular sieve catalyst 6# is obtained.

[0067] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0068] Weigh 20g of molecular sieve catalyst 6# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 175℃, stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0069] Comparative Example 4

[0070] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0071] Step (1): crystallize the original powder of Na-MOR (Si / Al ratio 15) molecular sieve in a crystallization solution, the composition of the crystallization solution is: H2O, NaOH, tetradecyl trimethyl ammonium chloride, silica sol, the mass ratio of these substances is 100: 0.05: 0.02: 5.5. The steps of adding the original powder of Na-MOR molecular sieve to the crystallization solution are: firstly, H2O, NaOH, tetradecyl trimethyl ammonium chloride are sequentially mixed with the original powder, and then heated to 85°C, and stirred for 5 hours under the condition of stirring speed of 80r / min, and then silica sol is slowly added, and the original powder of Na-MOR molecular sieve and the crystallization solution are crystallized in a ratio of 1kg: 10L. The crystallization temperature is 170°C, the time is 24h, and the stirring speed is 200r / min. The pH value of the washing filtrate is less than 9, the drying temperature is 110°C, and the drying time is 5h. Then, the SB powder binder is rolled into a ball, the ball diameter is 3-3.3mm, and the mass ratio of each substance is 1: 0.6 to obtain an intermediate product.

[0072] Step (2): The mass ratio of the intermediate product, ammonium nitrate and water is 1:0.6:10, the exchange temperature is 80°C, and the exchange time is 4 hours. The roasting temperature is 550°C, and the roasting time is 4 hours to obtain molecular sieve catalyst 7#.

[0073] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0074] Weigh 20g of molecular sieve catalyst 7# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 175℃, stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1 , and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0075] Comparative Example 5

[0076] A method for preparing a molecular sieve catalyst, the specific steps are as follows:

[0077] Step (1): using Na-MOR (Si / Al ratio 10) molecular sieve raw powder and silica sol binder to roll ball forming, the ball diameter is 3-3.3mm, the mass ratio of each substance is 1:0.2, and the formed molecular sieve is obtained. The formed molecular sieve is placed in a crystallization liquid for crystallization, and the crystallization liquid is composed of H2O, NaOH, dodecyltrimethylammonium chloride, and aluminum chloride, and the mass ratio of these substances is 100:0.05:0.02:0.1; the step of adding the crystallization liquid to the formed molecular sieve is: mixing H2O, NaOH, dodecyltrimethylammonium chloride, aluminum chloride with the formed molecular sieve, and the formed molecular sieve and the crystallization liquid are crystallized at a ratio of 1kg:10L. The crystallization temperature is 165°C, the time is 24h, and the stirring rate is 200r / min. The pH value of the washing filtrate is less than 9, the drying temperature is 110°C, and the drying time is 5h to obtain an intermediate product.

[0078] Step (2): The intermediate product is subjected to H ion exchange; the mass ratio of the intermediate product, ammonium nitrate and water is 1:0.5:10, the exchange temperature is 75°C, and the exchange time is 4h. The exchanged material is roasted at a temperature of 550°C and a roasting time of 4h to obtain molecular sieve catalyst 8#.

[0079] This embodiment also provides a catalyst activity test, the specific steps are as follows:

[0080] Weigh 20g of molecular sieve catalyst 8# for the activity test of preparing methyl acetate from dimethyl ether and carbon monoxide. Load it into a stainless steel reaction tube with an inner diameter of 43mm, then slowly increase the pressure to 2.0MPa with N2 gas and control the reaction temperature to 165°C. Stop nitrogen introduction and start introducing raw gas (in volume ratio, carbon monoxide: dimethyl ether = 7:1), and control the raw gas volume space velocity to 2000h -1, and start recording the reaction time. When the reaction time reaches 100 hours, the reaction product is analyzed online by gas chromatography. The activity test results are shown in Table 1.

[0081] Table 1 Test results of different catalyst activities

[0082]

[0083]

[0084] It can be seen from the average strength of the catalyst in Table 1 that the strength of the catalyst is not significantly reduced by the crystallization process after the catalyst is formed, and the industrial use standard can be reached. It can be seen from the activity test results in Table 1 that in the reaction of dimethyl ether and carbon monoxide to methyl acetate, there is a binder in the molecular sieve catalyst in Comparative Examples 1, 2, and 3. In the carbonylation reaction of dimethyl ether, the performance is that the dimethyl ether is 41.5%, 40.1%, and 38.4%, respectively, and the methyl acetate selectivity is 97.6%, 96.8%, and 95.9%, respectively. It can be seen that with the increase of the binder content in the molecular sieve catalyst, the dimethyl ether conversion rate and the methyl acetate selectivity are gradually reduced. Comparative Example 4 is to crystallize the original molecular sieve powder before forming it. The adhesive used in its forming is not correspondingly crystallized, so its performance is not improved, and it is shown that the dimethyl ether conversion rate is 39.5% and the methyl acetate selectivity is 96.2%. Comparative Example 5 is a catalyst #8 prepared under the same conditions as the catalyst #1 of the catalyst example of the present invention, showing a dimethyl ether conversion rate of 40.9% and a methyl acetate selectivity of 97.1%. The molecular sieve catalysts #1, #2 and #3 prepared by the method of the present invention have dimethyl ether conversion rates of 47.0%, 47.8% and 47.2% respectively in the dimethyl ether carbonylation reaction, and methyl acetate selectivities of 99.7%, 99.3% and 99.0% respectively. It can be seen that both the dimethyl ether conversion rate and the methyl acetate selectivity are significantly improved. It is illustrated that the molecular sieve catalyst prepared by the method of the present invention significantly improves the catalytic effect of the catalyst in the dimethyl ether and carbon monoxide carbonylation process.

[0085] from Figure 1 , 2 As can be seen from Figure 3, the intensity of each characteristic diffraction peak of XRD of the molecular sieve catalyst prepared by the method of the present invention is significantly improved, which indicates that the binder in the molecular sieve is converted into molecular sieve crystals in the crystallization liquid after molding, thereby improving the reaction activity site.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a molecular sieve catalyst, characterized in that: The method comprises the following steps: (1) placing the formed molecular sieve in a molecular sieve original powder crystallization liquid for crystallization and stirring, and then filtering, washing and drying to obtain an intermediate product; the formed molecular sieve is a molecular sieve formed by Na-MOR or Na-FER original powder and a binder; the molecular sieve original powder crystallization liquid is composed of H2O, NaOH, ammonium salt and silicon material or aluminum material; the mass ratio of H2O, NaOH, ammonium salt and silicon material or aluminum material is 100: 0.01-10.0: 0.01-2.0: 0.01-10.0; the ratio of the mass kg of the formed molecular sieve to the volume L of the molecular sieve original powder crystallization liquid is 1: 4-20; the crystallization temperature is 130-20 0℃, time is 12-120h, stirring rate is 100-500r / min; pH value of filtrate after washing is <9, drying temperature is 100-130℃, drying time is 1-20h; the ammonium salt is selected from any one or a mixture of hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride; the silicon material is any one or a mixture of silica sol, silicon powder or white carbon black; the aluminum material is any one or a mixture of aluminum chloride, aluminum sulfate, aluminum nitrate, sodium aluminate; The specific steps of adding the crystallization liquid to the formed molecular sieve are as follows: mixing water, NaOH, ammonium salt and the formed molecular sieve, then heating to 85±5°C, stirring at a stirring rate of 50-100r / min, stirring for 5±1 hours, and then slowly adding silicon material or aluminum material; after all the materials are added, crystallization treatment is performed; (2) The intermediate product is subjected to hydrogen ion exchange and calcination to obtain a molecular sieve catalyst; the molecular sieve catalyst is used for the carbonylation reaction of dimethyl ether and carbon monoxide.

2. The preparation method according to claim 1, characterized in that: The molding method is ball molding or extrusion molding; the ball diameter is 3-5mm, the extrusion diameter is 2-5mm, and the length is 3-5mm; the binder is any one of silica sol or SB powder or a combination of the two; the Si / A1 ratio of the Na-MOR or Na-FER molecular sieve raw powder is 5-50, and the mass ratio of the raw powder to the binder is 1:0.1-1.

0.

3. The preparation method according to claim 1, characterized in that: In step (2), the intermediate product is exchanged with a solution of ammonium salt and water, the mass ratio of the intermediate product, ammonium salt and water is 1:0.2-2.0:5-20, the exchange temperature is 60-90°C, and the exchange time is 2-10h; the roasting temperature is 500-600°C, and the roasting time is 2-10h.

4. The preparation method according to claim 3, characterized in that: The ammonium salt described in step (2) is selected from any one of ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium carbonate, or a mixture of several of them.

5. The molecular sieve catalyst prepared according to the method described in any one of claims 1 to 4.

6. The use of the molecular sieve catalyst according to claim 5, characterized in that: The molecular sieve catalyst described in claim 5 is used for the carbonylation reaction of dimethyl ether and carbon monoxide; that is, dimethyl ether and carbon monoxide are used as raw materials, and methyl acetate is obtained by reacting in a reactor filled with a molecular sieve catalyst, the reaction temperature is 150-210°C, the reaction pressure is 1.0-10.0MPa, and the raw material gas space velocity is 1000-10000h -1 The volume ratio of carbon monoxide to dimethyl ether in the raw gas is 5:1~20:

1.

7. The use of the molecular sieve catalyst according to claim 6, characterized in that: Before the reaction, the catalyst is pre-adsorbed with pyridine or methyl iodide at a temperature of 250-350° C. and a concentration of pyridine or methyl iodide of 0.1-10.0 v.%.

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