Preparation method of high-silica mordenite molecular sieve and application thereof

Abstract

The application discloses a preparation method of mother liquor recycling synthesis of high-silicon mordenite molecular sieve and application of the high-silicon mordenite molecular sieve as a dimethyl ether carbonylation reaction catalyst for preparing methyl acetate, and belongs to the technical field of industrial catalysis. The method comprises the following steps: S1, after the synthesis of the molecular sieve, the mother liquor is obtained through flocculation and filtration to obtain mother liquor I; S2, a mixture containing the mother liquor I, a silicon source, an aluminum source, an alkali source and a template T1 is placed in a closed container, and a mother liquor sol with a primary structural unit is obtained through crystallization; S3, a mixture I containing a silicon source, an aluminum source, an alkali source, a template T2 and water is aged to obtain a silicon-aluminum sol; S4, a mixture II containing the mother liquor sol and the silicon-aluminum sol is placed in a closed container, and high-silicon mordenite molecular sieve is obtained through crystallization I. The method makes the raw material components in the discharged mother liquor be recycled, improves the raw material utilization rate, reduces the synthesis cost, reduces the environmental protection pressure of enterprises, shortens the crystallization time of the molecular sieve synthesis, and improves the crystallinity of the product.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a mother liquor recycling synthesis high-silicon mordenite molecular sieve, which shortens a crystallization time and improves product crystallinity, and application of the high-silicon mordenite molecular sieve as a dimethyl ether carbonylation catalyst for preparing methyl acetate, and belongs to the technical field of industrial catalysis. BACKGROUND

[0002] Since the artificial synthesis of molecular sieves was successfully achieved in the 1950s, molecular sieves have been widely applied in the fields of petroleum and chemical industry, synthesis, catalysis and separation. In many synthesis methods of molecular sieves, the hydrothermal synthesis method is the most commonly used synthesis method in industry, that is, the nucleation and crystal growth of the molecular sieve are completed in an alkaline aqueous solution under certain temperature and pressure conditions, and finally the target molecular sieve is obtained. Due to the factors that the synthesis mother liquor is generally a strong alkaline waste liquid, the composition is complex, the discharge amount is large, and the colloid is easy to be formed, the discharge is limited by the national environmental protection regulations, and the discharge needs to be treated to meet the standards before being discharged, the treatment process is complex and the cost is high, in addition, the synthesis molecular sieve mother liquor also contains a certain amount of synthesis raw materials with utilization value. Therefore, from the aspects of resource utilization and environmental protection, recycling and reusing the synthesis molecular sieve mother liquor has great significance.

[0003] Chinese patent CN1207085A discloses a mother liquor recycling method of non-spherical nano MFI molecular sieve, a small amount of synthesis mother liquor is added in the initial gel during synthesis, but the recycling mother liquor is less utilized, and the method cannot play a role in reducing waste liquid discharge in industry; Chinese patents CN101121148A and CN103706393A both directly utilize the slurry by adding a binder and a matrix component, and the treated slurry is directly sprayed or enters a molding process, but the influence of the added mother liquor on the performance and service life of the catalyst is not discussed. Chinese patent CN102225772A discloses a utilization method of ITQ-2 molecular sieve mother liquor, mainly recycling and reusing the template agent in the mother liquor, but the complete crystallization recovery of the template agent is difficult and the process is complicated. SUMMARY

[0004] According to a first aspect of the application, a preparation method of a high-silicon mordenite molecular sieve is provided. The method enables the raw material components in the mother liquor to be discharged to be recycled again, improves the utilization rate of raw materials, reduces the synthesis cost and alleviates the environmental protection pressure of enterprises.

[0005] A preparation method of a high-silicon mordenite molecular sieve, comprising the following steps:

[0006] S1, a mother liquor after synthesis of a molecular sieve is obtained by flocculation and filtration to obtain a mother liquor I;

[0007] S2, placing the mixture containing the mother liquor I, silicon source, aluminum source, alkali source, and template T1 in a closed container, and crystallizing to obtain a mother liquor sol having a primary structural unit;

[0008] S3, placing the mixture I containing the silicon source, aluminum source, alkali source, template T2, and water in a closed container, and aging to obtain a silicon-aluminum sol;

[0009] S4, placing the mixture II containing the mother liquor sol and the silicon-aluminum sol in a closed container, and crystallizing I to obtain a high-silica mordenite molecular sieve.

[0010] Optionally, the mixture in step S2 has a molar composition of SiO2:Al2O3:Na2O:H2O:T1 = 1:(0.01-0.1):(0.05-0.3):(10-150):(0.01-0.03).

[0011] Optionally, the mixture in step S2 has a molar composition of SiO2:Al2O3:Na2O:H2O:T1 = 1:(0.02-0.035):(0.15-0.27):(50-110):(0.01-0.025).

[0012] Optionally, the crystallization conditions in step S2 are as follows:

[0013] The temperature is 80-120°C.

[0014] The time is 4-12 h.

[0015] Optionally, the temperature is independently selected from any value or a range between any two values selected from the group consisting of 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C.

[0016] Optionally, the time is independently selected from any value or a range between any two values selected from the group consisting of 4.0 h, 4.5 h, 5.0 h, 5.5 h, 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8.0 h, 8.5 h, 9.0 h, 9.5 h, 10.0 h, 10.5 h, 11.0 h, 11.5 h, and 12.0 h.

[0017] Optionally, the aging conditions in step S3 are as follows:

[0018] The temperature is 20-110°C.

[0019] The time is 2-24 h.

[0020] Optionally, the temperature is independently selected from any value or range between any two values of 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃.

[0021] Optionally, the time is independently selected from any value or range between any two values of 2.0h, 2.5h, 3.0h, 3.5h, 4.0h, 4.5h, 5.0h, 5.5h, 6.0h, 6.5h, 7.0h, 7.5h, 8.0h, 8.5h, 9.0h, 9.5h, 10.0h, 10.5h, 11.0h, 11.5h, 12.0h, 13.0h, 14.0h, 15.0h, 16.0h, 17.0h, 18.0h, 19.0h, 20.0h, 21.0h, 22.0h, 23.0h, 24.0h.

[0022] Optionally, in step S4, the mass ratio of the mother liquor sol to the silicon-aluminum sol is 0.1-10:1.

[0023] Optionally, in step S4, the mass ratio of the mother liquor sol to the silicon-aluminum sol is independently selected from any value or range between any two values of 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1.

[0024] Optionally, in step S4, the mixture II has a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:(0.01-0.1):(0.05-0.3):(10-50):(0.01-0.30).

[0025] Optionally, in step S4, the mixture II has a molar composition of SiO2:Al2O3:Na2O:H2O:T=1:(0.011-0.1):(0.10-0.3):(15-35):(0.1-0.25).

[0026] Optionally, in step S4, the crystallization I has the following conditions:

[0027] The temperature is 120-200℃;

[0028] The time is 12-120h.

[0029] Optionally, the temperature is independently selected from any value or a range between any two values of 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃.

[0030] Optionally, the time is independently selected from any value or a range between any two values of 12.0h, 13.0h, 14.0h, 15.0h, 16.0h, 17.0h, 18.0h, 19.0h, 20.0h, 21.0h, 22.0h, 23.0h, 24.0h, 25.0h, 30.0h, 40.0h, 50.0h, 60.0h, 70.0h, 80.0h, 90.0h, 100.0h, 110.0h, 120.0h.

[0031] Optionally, the mother liquor after step S4 is repeated with step S1.

[0032] Optionally, the high-silica mordenite molecular sieve has a silica-alumina ratio of 20-45.

[0033] Optionally, the silicon source is independently selected from at least one of silica sol, water glass, white carbon black, diatomite.

[0034] Optionally, the aluminum source is independently selected from at least one of sodium aluminate, aluminum isopropoxide, aluminum hydroxide, aluminum sulfate.

[0035] Optionally, the alkali source is independently selected from at least one of alkali metal hydroxide.

[0036] Optionally, the template T is selected from at least one 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, cycloheptane amine, cyclopentane amine.

[0037] According to a second aspect of the present application, there is provided a use of a high-silica mordenite molecular sieve.

[0038] The high-silica mordenite molecular sieve prepared by the method described above is used as a dimethyl ether carbonylation reaction catalyst, and the dimethyl ether carbonylation reaction catalyst is obtained by ammonium ion exchange of the high-silica mordenite molecular sieve.

[0039] Optionally, the high-silica mordenite molecular sieve is used to catalyze synthesis of methyl acetate from dimethyl ether and carbon monoxide.

[0040] The reaction conditions are as follows:

[0041] The temperature is 150-260℃.

[0042] The pressure is 1-10 MPa.

[0043] The reverse total space velocity is 1000-20000 h-1. -1 .

[0044] Optionally, the temperature is independently selected from any value or a range value between any two of 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃.

[0045] Optionally, the pressure is independently selected from any value or a range value between any two of 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa.

[0046] Optionally, the reverse total space velocity is independently selected from any value or a range value between any two of 1000 h-1, 2000 h-1, 3000 h-1, 4000 h-1, 5000 h-1, 6000 h-1, 7000 h-1, 8000 h-1, 9000 h-1, 10000 h-1, 11000 h-1, 12000 h-1, 13000 h-1, 14000 h-1, 15000 h-1, 16000 h-1, 17000 h-1, 18000 h-1, 19000 h-1, 20000 h-1. -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 .

[0047] Optionally, the molar ratio of the dimethyl ether to the carbon monoxide is 1:1-50.

[0048] ​​​​​​​​​​​​​​​​​​​Optionally, the molar ratio of the dimethyl ether to the carbon monoxide is independently selected from 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, 1:30, 1:40, 1:50.

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

[0050] The temperature is 160-220℃.

[0051] The pressure is 2-6MPa.

[0052] Optionally, the molar ratio of the dimethyl ether to the carbon monoxide is 1:1-10.

[0053] Optionally, the molar ratio of the dimethyl ether to the hydrogen gas feed is 1:40-60.

[0054] The beneficial effects that can be produced by the present application include:

[0055] The present application provides a preparation method of a high-silicon mordenite molecular sieve. The method uses concentrated mother liquor, greatly reduces the discharge of waste liquid, and increases the product yield of a single kettle compared to directly using the mother liquor for synthesis. The concentrated mother liquor after crystallization contains primary structural units, which shortens the crystallization time of the molecular sieve synthesis, and improves the crystallinity of the molecular sieve and the B / (B+L) ratio of the acid sites of the molecular sieve, thereby improving the catalytic activity of the catalyst in the dimethyl ether carbonylation reaction. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 XRD spectra of the sol of the mother liquor containing primary structural units in Examples 1, 3, and 5.

[0057] Figure 2 XRD spectra of the products of Examples 1, 3, 5, and Comparative Example 1.

[0058] Figure 3 Crystallization curves of Example 3 and Comparative Example 1. DETAILED DESCRIPTION

[0059] The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

[0060] Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0061] The analysis methods in the examples and comparative examples of the present application are as follows:

[0062] X-ray powder diffraction phase analysis (XRD) was performed using a SmartLab SE X-ray diffractometer from Rigaku, Japan, with a Cu target, a voltage of 40 kV, and a current of 30 mA.

[0063] The crystallinity is calculated by comparing the sum of the peak heights of the 8 characteristic diffraction peaks at 2-theta of 6.51, 9.77, 13.45, 19.68, 22.20, 25.75, 26.42, and 27.67° in the standard XRD pattern of mordenite with the sum of the peak heights of the 8 characteristic diffraction peaks of the sample, according to the following formula:

[0064] P i = (∑I i / ∑I m )P m

[0065] In the formula, ∑I m , ∑I i are the sum of the peak heights of the corresponding characteristic peaks of the standard sample and the sample, respectively; P m , P i are the crystallinities of the standard sample and the sample, respectively.

[0066] The elemental composition (XRF) is determined by using a ZSXPrimus III+ X-ray fluorescence spectrometer of Rigaku Corporation, Japan, with a power of 3 KW.

[0067] Example 1

[0068] The previous batch of crystallized molecular sieve slurry product is subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve is recovered. The mother liquor is subjected to flocculation treatment and filtration, and the contents of components such as SiO2, Al2O3, and Na2O in the mother liquor are analyzed. NaOH is used as an alkali source, sodium silicate is used as a silicon source, sodium aluminate is used as an aluminum source, and cetyltrimethylammonium chloride is used as a template agent, and the molar composition is SiO2:Al2O3:Na2O:H2O:T = 1:0.04:0.2:80:0.015. The gel is transferred into a reaction kettle, and kept at 70°C for 8 h to obtain a primary structure unit mother liquor sol;

[0069] The silicon source, the aluminum source, the alkali source, the template agent, and water are stirred and aged to prepare a silicon-aluminum sol. The primary structure unit mother liquor sol and the silicon-aluminum sol are mixed, and the molar composition after the addition is SiO2:Al2O3:Na2O:H2O:T = 1:0.025:0.15:25:0.17. The mixture is stirred for a period of time to make it uniform, and then transferred into a reaction kettle and heated to 170°C and kept for 48 h. The obtained sample is washed with deionized water until neutral, dried at 120°C for 12 h, and calcined at 560°C for 4 h to obtain a high-silicon mordenite molecular sieve.

[0070] Example 2

[0071] The previous batch of crystallized molecular sieve slurry product was subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve was recovered. The mother liquor was subjected to flocculation treatment and filtration, and the SiO2, Al2O3, Na2O, and other component contents in the mother liquor were analyzed. NaOH was used as an alkali source, silica sol was used as a silicon source, aluminum hydroxide was used as an aluminum source, and tetraethylammonium chloride was used as a template agent. The molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.03:0.15:65:0.02. The gel was transferred to a reaction kettle, kept at 70°C for 8h, and a primary structure unit mother liquor sol was obtained;

[0072] The silicon source, the aluminum source, the alkali source, the template agent, and water were stirred and aged to prepare a silicon-aluminum sol. The primary structure unit mother liquor sol and the silicon-aluminum sol were mixed, and after the addition, the molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.016:0.12:20:0.25. The mixture was stirred for a period of time to make it uniform, and then transferred to a reaction kettle and heated to 180°C for 42h. The obtained sample was washed with deionized water until neutral, dried at 120°C for 12h, and calcined at 560°C for 4h to obtain a high-silicon mordenite molecular sieve.

[0073] Example 3

[0074] The previous batch of crystallized molecular sieve slurry product was subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve was recovered. The mother liquor was subjected to flocculation treatment and filtration, and the SiO2, Al2O3, Na2O, and other component contents in the mother liquor were analyzed. NaOH was used as an alkali source, silica sol was used as a silicon source, aluminum hydroxide was used as an aluminum source, and tetraethylammonium chloride was used as a template agent. The molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.03:0.15:65:0.02. The gel was transferred to a reaction kettle, kept at 70°C for 8h, and a primary structure unit mother liquor sol was obtained;

[0075] The silicon source, the aluminum source, the alkali source, the template agent, and water were stirred and aged to prepare a silicon-aluminum sol. The primary structure unit mother liquor sol and the silicon-aluminum sol were mixed, and after the addition, the molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.016:0.12:20:0.25. The mixture was stirred for a period of time to make it uniform, and then transferred to a reaction kettle and heated to 180°C for 42h. The obtained sample was washed with deionized water until neutral, dried at 120°C for 12h, and calcined at 560°C for 4h to obtain a high-silicon mordenite molecular sieve.

[0076] Example 4

[0077] The previous batch of crystallized molecular sieve slurry product was subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve was recovered. The mother liquor was subjected to flocculation treatment and filtration, and the SiO2, Al2O3, Na2O, and other component contents in the mother liquor were analyzed. NaOH was used as an alkali source, silica sol was used as a silicon source, sodium aluminate was used as an aluminum source, and cetyltrimethylammonium chloride was used as a template agent. The molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.016:0.14:90:0.018. The gel was transferred to a reaction kettle, and kept at 70°C for 8 h to obtain a mother liquor sol containing primary structural units.

[0078] The silicon source, the aluminum source, the alkali source, the template agent, and water were stirred and aged to prepare a silicon-aluminum sol. The mother liquor sol containing primary structural units and the silicon-aluminum sol were mixed, and after the addition, the molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.040:0.25:30:0.10. The mixture was stirred for a period of time to make it uniform, and was then transferred to a reaction kettle and heated to 180°C for 30 h. The obtained sample was washed with deionized water until neutral, dried at 120°C for 12 h, and calcined at 560°C for 4 h to obtain a high-silica mordenite molecular sieve.

[0079] Example 5

[0080] The previous batch of crystallized molecular sieve slurry product was subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve was recovered. The mother liquor was subjected to flocculation treatment and filtration, and the SiO2, Al2O3, Na2O, and other component contents in the mother liquor were analyzed. NaOH was used as an alkali source, silica sol was used as a silicon source, sodium aluminate was used as an aluminum source, and cetyltrimethylammonium chloride was used as a template agent. The molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.016:0.14:90:0.018. The gel was transferred to a reaction kettle, and kept at 70°C for 8 h to obtain a mother liquor sol containing primary structural units.

[0081] The silicon source, the aluminum source, the alkali source, the template agent, and water were stirred and aged to prepare a silicon-aluminum sol. The mother liquor sol containing primary structural units and the silicon-aluminum sol were mixed, and after the addition, the molar composition was SiO2:Al2O3:Na2O:H2O:T = 1:0.040:0.25:30:0.10. The mixture was stirred for a period of time to make it uniform, and was then transferred to a reaction kettle and heated to 180°C for 30 h. The obtained sample was washed with deionized water until neutral, dried at 120°C for 12 h, and calcined at 560°C for 4 h to obtain a high-silica mordenite molecular sieve.

[0082] Comparative Example 1

[0083] A sample was prepared by using NaOH as alkali source, silica sol as silicon source, aluminum isopropoxide as aluminum source, and hexamethylene imine as template agent, with a molar composition of Si02:Al203:Na20:H20:T = 1:0.025:0.15:33:0.28, stirring uniformly, transferring to a reaction kettle after stirring, heating to 180°C for 72 hours, washing the obtained sample with deionized water until neutral, drying at 120°C for 12 hours, and calcining at 560°C for 4 hours to obtain the mordenite molecular sieve of Comparative Example 1.

[0084] Comparative Example 2

[0085] The slurry product of the crystallized molecular sieve of the previous batch was subjected to solid-liquid separation, and the mother liquor after synthesis of the molecular sieve was recovered. The mother liquor was subjected to flocculation treatment and filtration, and the Si02, Al203, Na20, and other component contents in the mother liquor were analyzed. A sample was prepared by using NaOH as alkali source, silica sol as silicon source, aluminum sulfate as aluminum source, and cetyltrimethylammonium chloride as template agent, with a molar composition of Si02:Al203:Na20:H20:T = 1:0.027:0.015:25:0.18, stirring uniformly, transferring to a reaction kettle after stirring, heating to 180°C for 72 hours, washing the obtained sample with deionized water until neutral, drying at 120°C for 12 hours, and calcining at 560°C for 4 hours to obtain the mordenite molecular sieve of Comparative Example 2.

[0086] A certain amount of the Na-MOR molecular sieve was weighed into a beaker, and 2 mol / L ammonium nitrate solution was used for ammonium ion exchange at a solid-liquid mass ratio of 1:8 at 80°C for 3 hours. After repeating the ammonium ion exchange for 3 times, the sample was dried at 120°C for 12 hours, and then calcined in a muffle furnace at 550°C for 4 hours to obtain the H-MOR molecular sieve catalyst.

[0087] The mordenite molecular sieve catalyst sample prepared above was pressed into a sheet, crushed and sieved, and 1 g of 20-40 mesh catalyst was loaded into a fixed bed reactor. The catalyst 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 of DME:N2:CO was 1:13:7, and the volume space velocity was 2000 h-1. -1 The product analysis was performed on a Fulie GC9790 type gas chromatograph, with an HP-PLOT / Q column and an FID detector. The dimethyl ether (DME) conversion rate and methyl acetate (MA) selectivity data were calculated by area normalization method. The results are shown in Table 1.

[0088] In the examples and comparative examples, the conversion rate of dimethyl ether and the selectivity of methyl acetate were calculated based on the carbon molar number of dimethyl ether:

[0089] Dimethyl ether conversion = [(carbon moles of dimethyl ether in raw gas) - (carbon moles of dimethyl ether in product)] ÷ (carbon moles of dimethyl ether in raw gas) x (100%);

[0090] Methyl acetate selectivity = (2 / 3) x (carbon moles of methyl acetate in product) ÷ [(carbon moles of dimethyl ether in raw gas) - (carbon moles of dimethyl ether in product)] x (100%).

[0091] Table 1

[0092]

[0093] As can be seen from the above table, the use of mother liquor in the examples shortens the crystallization time of the molecular sieve synthesis; improves the crystallinity of the molecular sieve and the B / (B+L) ratio in the acid sites of the molecular sieve, thereby improving the catalytic activity of the catalyst in the dimethyl ether carbonylation reaction.

[0094] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed above, the present application is not limited thereto. Any person skilled in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the present application, and such changes or modifications are equivalent to equivalent embodiments, and all of them are within the scope of the technical solution.

Claims

1. A method for preparing a high-silica mordenite zeolite molecular sieve, characterized in that, Includes the following steps: S1. The mother liquor after molecular sieve synthesis is subjected to flocculation and filtration to obtain mother liquor I; S2. Place the mixture containing the above-mentioned mother liquor I, silicon source, aluminum source, alkali source and template agent T1 in a sealed container and crystallize to obtain a mother liquor sol with primary structural units. S3. Mixture I containing silicon source, aluminum source, alkali source, template agent T2, and water is aged to obtain aluminosilicate sol; S4. The mixture II containing the above mother liquor sol and the above silica-alumina sol is placed in a sealed container, and I is crystallized to obtain high-silica mordenite molecular sieve. The crystallization conditions in step S2 are as follows: The temperature is 80~120℃; The time is 4~12 hours; The mixture in step S2 has a molar composition of SiO2:Al2O3:Na2O:H2O:T1=1:(0.01~0.1):(0.05~0.3):(10~150):(0.01~0.03); In step S4, the molar composition of mixture II is SiO2:Al2O3:Na2O:H2O:T=1:(0.01~0.1):(0.05~0.3):(10~50):(0.01~0.30); The silicon-to-aluminum ratio of the high-silica mordenite molecular sieve is 20-45.

2. The preparation method according to claim 1, characterized in that, The mixture in step S2 has the following molar composition: SiO2:Al2O3:Na2O:H2O:T1=1:(0.02~0.035):(0.15~0.27):(50~110):(0.01~0.025).

3. The preparation method according to claim 1, characterized in that, The aging conditions for mixture I in step S3 are as follows: The temperature is 20~110℃; The time is 2 to 24 hours.

4. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of the mother liquor sol to the silica-alumina sol is 0.1~10:

1.

5. The preparation method according to claim 1, characterized in that, In step S4, the molar composition of mixture II is SiO2:Al2O3:Na2O:H2O:T=1:(0.011~0.1):(0.10~0.3):(15~35):(0.1~0.25).

6. The preparation method according to claim 1, characterized in that, In step S4, the conditions for crystallization I are as follows: The temperature is 120~200℃; The time is 12~120 hours.

7. The preparation method according to claim 1, characterized in that, Repeat step S1 with the mother liquor after the reaction in step S4.

8. The preparation method according to claim 1, characterized in that, The silicon source is independently selected from at least one of silica sol, water glass, silica, and diatomaceous earth.

9. The preparation method 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.

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

11. The preparation method according to claim 1, characterized in that, The template agent T is selected from at least one of the following: 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.

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