CN112934255B

CN112934255B - Preparation method of bimetallic molecular sieve catalyst, bimetallic molecular sieve catalyst and application

Info

Publication number: CN112934255B
Application number: CN201911261758.XA
Authority: CN
Inventors: 王胜; 韦小丽; 王树东; 徐德康; 汪明哲
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2024-05-10
Anticipated expiration: 2039-12-10
Also published as: CN112934255A

Abstract

The application discloses a preparation method of a bimetallic molecular sieve catalyst, the bimetallic molecular sieve catalyst and application. The preparation method at least comprises the following steps: s100) loading a mixture containing NH ₄ -UZM-9 molecular sieve and a metal source to obtain a precursor; s200) roasting the precursor to obtain a bimetallic molecular sieve catalyst; wherein the metal source is at least one selected from a Cu source and a Ce source. The bimetallic molecular sieve catalyst prepared by the method ensures the conversion rate of AN (acrylonitrile) and the selectivity of products in the AN tail gas removal process.

Description

Preparation method of bimetallic molecular sieve catalyst, bimetallic molecular sieve catalyst and application

Technical Field

The application relates to a preparation method of a bimetallic molecular sieve catalyst, the bimetallic molecular sieve catalyst and application thereof, and belongs to the technical field of gas purification.

Background

Acrylonitrile is an important raw material that can be used to produce a wide variety of chemicals and polymers. For example, acrylic fibers and resins (acrylonitrile-butadiene-styrene resins) and the like can be produced using acrylonitrile and can be used as intermediates for the production of adiponitrile and acrylamide. However, acrylonitrile is a nitrogen-containing VOC and has extremely strong toxicity and carcinogenicity, so many countries have begun to develop related legal policies to control the emission of acrylonitrile.

Typical methods for treating AN-containing exhaust gas mainly include a high-temperature incineration method and a catalytic combustion method. Although the high-temperature incineration method has good AN removal performance, the method has the problems of high energy consumption and easiness in secondary pollution. The catalytic combustion method needs lower temperature, and has excellent AN removal performance and good N ₂ selectivity. The catalyst with the best AN removal reaction performance is a Cu-ZSM-5 catalyst, the catalyst can completely convert AN at 350 ℃ and has good N ₂ selectivity, but in order to further improve the AN catalytic combustion performance of the catalyst, a catalyst needs to be sought, and the catalyst needs to have proper oxidation-reduction performance, and although the higher the oxidation-reduction performance is, the lower the AN complete removal temperature is, but the selectivity of N ₂ is reduced due to the excessively high oxidation-reduction performance.

Disclosure of Invention

According to one aspect of the application, a preparation method of a bimetallic molecular sieve catalyst is provided, and the bimetallic molecular sieve catalyst prepared by the method ensures the conversion rate of AN (acrylonitrile) and the selectivity of products in the AN (acrylonitrile) tail gas removal process.

A method for preparing a bimetallic molecular sieve catalyst, which at least comprises the following steps:

S100) loading a mixture containing NH ₄ -UZM-9 molecular sieve and a metal source to obtain a precursor;

s200) roasting the precursor to obtain a bimetallic molecular sieve catalyst;

Wherein the metal source is at least one selected from a Cu source and a Ce source.

Preferably, the metal sources are a Cu source and a Ce source.

In the present application, the bimetallic molecular sieve catalyst is designated Cu/Ce-UZM-9.

NH ₄ -UZM-9 molecular sieve is obtained by exchanging NH ⁴⁺ with Na-UZM-9 molecular sieve.

The Na-UZM-9 molecular sieve is prepared by a seed crystal synthesis method.

One possible method for preparing the NH ₄ -UZM-9 molecular sieve is described below:

(1) Preparing a Na-UZM-9 molecular sieve by a seed crystal synthesis method, and removing an organic template agent by a roasting method to obtain the Na-UZM-9 molecular sieve;

(2) And (3) exchanging NH ⁴⁺ with the mixture III containing the Na-UZM-9 molecular sieve and the ammonium salt, and centrifugally washing and drying the product to obtain the NH4-UZM-9 molecular sieve.

Alternatively, NH ⁴⁺ is derived from an ammonium salt, which is at least one of ammonium nitrate, ammonium chloride, ammonium acetate, ammonium sulfate, preferably ammonium chloride and ammonium nitrate.

Alternatively, the concentration of the ammonium salt in the mixture III is between 0.1 and 5.0mol/L, preferably between 0.5 and 2mol/L.

Alternatively, the NH ⁴⁺ exchange is carried out at a temperature of 25 to 95℃and preferably 60 to 85 ℃.

Alternatively, the number of NH ⁴⁺ exchanges is 1 to 9, preferably 1 to 3.

Optionally, the Cu source is a Cu salt;

the Cu salt comprises at least one of copper nitrate, copper chloride, copper acetate and copper sulfate.

Preferably, the Cu salt is copper nitrate and/or copper chloride.

Optionally, the Ce source is a Ce salt;

The Ce salt comprises at least one of cerium nitrate, ammonium cerium nitrate, cerium chloride and cerium acetate.

Preferably, the Ce salt is cerium nitrate and/or cerium chloride.

Optionally, in step S100, the loading is selected from any one of a liquid phase ion exchange mode, a solid phase ion exchange mode, a spin-on ion exchange mode, and an isovolumetric impregnation mode.

Optionally, the step S100 includes the steps of:

S100-1) carrying out liquid-phase Cu ²⁺ ion exchange and liquid-phase Ce ³⁺ ion exchange on an aqueous solution containing NH ₄ -UZM-9 molecular sieve, cu salt and Ce salt at the temperature of 20-95 ℃ to obtain a precursor.

Preferably, the temperature at which the liquid phase ion exchange is carried out is 45-90 ℃.

Alternatively, in step S100-1, the concentration of Cu salt in the aqueous solution is 0.001 to 5.0mol/L.

Preferably, in step S100-1, the concentration of Cu salt in the aqueous solution is 0.005-1.5mol/L.

Optionally, in step S100-1, the concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L.

Preferably, in step S100-1, the concentration of Ce salt in the aqueous solution is 0.05-1.9mol/L.

Optionally, the mass percentage of the NH ₄ -UZM-9 molecular sieve in the aqueous solution is 2-10wt%.

Alternatively, in step S100-1, the number of times of the liquid phase ion exchange is1 to 9 times, preferably 2 to 6 times.

Optionally, the step S100 includes the steps of:

S100-2) carrying out solid-phase Cu ²⁺ ion exchange and solid-phase Ce ³⁺ ion exchange on a solid-phase mixture containing NH ₄ -UZM-9 molecular sieve, cu salt and Ce salt at the temperature of 200-450 ℃ to obtain a precursor.

Preferably, in step S100-2, the temperature of the solid phase ion exchange is 250-350 ℃.

Optionally, in step S100-2, the Cu salt is present in the solid phase mixture in a mass percentage of 5 to 10wt%.

Optionally, in step S100-2, the mass percentage of Ce salt in the solid phase mixture is 50-70 wt%.

Alternatively, in step S100-2, the mass percent of NH ₄ -UZM-9 molecular sieve in the solid phase mixture is 30-40 wt%.

Optionally, the step S100 includes the steps of:

S100-3) carrying out Cu ²⁺ ion exchange and Ce ³⁺ ion exchange on an aqueous solution containing NH ₄ -UZM-9 molecular sieve, cu salt and Ce salt at the temperature of 35-70 ℃ under the condition of rotary evaporation to obtain a precursor.

Preferably, the spin-on ion exchange is carried out at a temperature of 45-50 ℃.

Optionally, in step S100-3, the concentration of Cu salt in the aqueous solution is 0.001-5.0 mol/L.

Preferably, in step S100-3, the concentration of Cu salt in the aqueous solution is 0.01 to 3.0mol/L.

Optionally, in step S100-3, the concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L.

Preferably, in step S100-3, the concentration of Ce salt in the aqueous solution is 0.05-1.9mol/L.

The mass percentage of the NH ₄ -UZM-9 molecular sieve in the aqueous solution is 2-10wt%.

Alternatively, in step S100-3, the number of spin-steaming ion exchange is1 to 9, preferably 2 to 6.

Optionally, the step S100 includes the steps of:

S100-4) carrying out isovolumetric impregnation on an aqueous solution containing NH ₄ -UZM-9 molecular sieve, cu salt and Ce salt at 15-25 ℃ to obtain a precursor.

Optionally, in step S100-4, the concentration of Cu salt in the aqueous solution is 0.001-5.0 mol/L.

Preferably, in step S100-4, the concentration of Cu salt in the aqueous solution is 0.005-1.5mol/L.

Optionally, in step S100-4, the concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L.

Preferably, in step S100-4, the concentration of Ce salt in the aqueous solution is 0.05-1.9mol/L.

Alternatively, in step S100-4, the number of times of impregnation is 1 to 9 times, preferably 2 to 6 times.

Optionally, in step S200, the firing temperature is 350-750 ℃.

Preferably, the firing temperature is 450-600 ℃.

Alternatively, the firing time is 1 to 8 hours.

Preferably, the calcination time is 2-6 hours.

According to a further aspect of the present application there is also provided a bimetallic molecular sieve catalyst obtainable by the process of any one of the above.

Optionally, the bimetallic molecular sieve catalyst comprises a carrier framework and a metal element supported on the carrier framework;

The carrier framework comprises an NH ₄ -UZM-9 molecular sieve;

the metal element comprises at least one of Cu element and Ce element;

wherein the Cu element is an active center; and the Ce element is an auxiliary agent.

Preferably, the metal element includes Cu element and Ce element.

Optionally, the loading of the Cu element in the bimetallic molecular sieve catalyst is 1-12 wt%.

Preferably, the loading of the Cu element in the bimetallic molecular sieve catalyst is 3-8wt%.

Optionally, the loading of the Ce element in the bimetallic molecular sieve catalyst is 1-70 wt%.

Preferably, the loading of the Ce element in the bimetallic molecular sieve catalyst is 5-35 wt%.

Optionally, the specific surface area of the bimetallic molecular sieve catalyst is 250-500 m ²/g.

According to a further aspect of the present application there is also provided a catalyst for the removal of acrylonitrile, the catalyst comprising any one of the bimetallic molecular sieve catalyst obtained by any one of the methods of preparation described above and/or the bimetallic molecular sieve catalyst of any one of the claims described above.

The application also provides a method for removing acrylonitrile, which is to contact the gas containing acrylonitrile with the catalyst to remove the acrylonitrile.

The catalyst is applied to removing acrylonitrile tail gas.

The application has the beneficial effects that:

1) According to the preparation method of the bimetallic molecular sieve catalyst, cu ²⁺ and Ce ³⁺ are loaded on a UZM-9 carrier framework, cu ²⁺ is used as a main active center, ce ³⁺ is used as AN auxiliary agent, the oxidation-reduction performance of Cu can be improved through the introduction of Ce, and with the increase of the Ce loading amount, the migration of Cu species to the outside of the crystal is promoted, so that the active adsorption and reaction sites of reactant molecules are increased (figure 7), and the AN catalytic combustion performance of the catalyst is improved.

2) The bimetallic AN tail gas removal catalyst provided by the application has higher crystallinity and specific surface area, has good AN removal activity, can completely convert AN at 270 ℃, maintains the selectivity of CO ₂ at 100% and the selectivity of N ₂ at more than 90% in a wider temperature range (150-550 ℃), and shows excellent product selectivity.

Drawings

The XRD patterns of the catalysts prepared in examples 1, 2, 3, 4, 5 are shown in fig. 1, respectively;

FIG. 2 is an Ar gas adsorption/desorption curve of a catalyst in example 3;

FIG. 3 is AN AN conversion activity curve of the catalysts of examples 1 to 6 in AN acrylonitrile removal evaluation test;

FIG. 4 is a plot of the selectivity of CO ₂ in the acrylonitrile removal evaluation test for the catalysts of examples 1-6;

FIG. 5 is a plot of the selectivity of N ₂ in the acrylonitrile removal evaluation test for the catalysts of examples 1-6;

FIG. 6 is a graph of the H ₂ -TPR curves for the catalysts prepared in examples 1 to 6;

fig. 7 is a Cu 2pXPS test chart of the catalysts prepared in example 1, examples 3 to 6.

Detailed Description

The present application is described in detail below with reference to examples, but the present application is not limited to these examples.

Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.

In the embodiment of the application, the conversion rate and selectivity are calculated as follows:

The conversion of acrylonitrile was = [ acrylonitrile _{( An inlet )} -acrylonitrile _{( An outlet )} ]/acrylonitrile _{( An inlet )};

Selectivity of CO ₂ = [ acrylonitrile _{( An inlet )} -acrylonitrile _{( An outlet )} -carbon monoxide _{( An outlet )} ]/acrylonitrile _{( An inlet )} -acrylonitrile _{( An outlet )};

Selectivity of N ₂ = [ acrylonitrile _{( An inlet )} -acrylonitrile _{( An outlet )} -nitric oxide _{( An outlet )} -nitrogen dioxide _{( An outlet )} -ammonia _{( An outlet )} -nitrous oxide _{( An outlet )} ]/acrylonitrile _{( An inlet )} -acrylonitrile _{( An outlet )};

The above calculation formula is given in ppm.

The sodium molecular sieve is prepared by a seed crystal synthesis method. Reference may be made to patent (201610956326.0).

In the present application, the XRD tester is PANALYTICAL X' pert diffractometer.

The specific surface area tester is Autosorb-iQ2.

The H ₂ -TPR tester is CHEMBET 3000.

The XPS tester is ESCALAB 250Xi.

According to one embodiment of the application, a microporous molecular sieve type bimetallic AN tail gas removal catalyst is prepared by adopting a liquid phase ion exchange method, and the specific steps are as follows:

(2) Carrying out NH ₄ ⁺ exchange on the Na-UZM-9 molecular sieve, and carrying out centrifugal washing and drying on the product to obtain the NH ₄ -UZM-9 molecular sieve;

(3) Carrying out liquid-phase Cu ²⁺ and Ce ³⁺ exchange on the NH ₄ -UZM-9 molecular sieve, and centrifugally washing and drying the product to obtain a bimetallic catalyst precursor;

(4) Roasting the bimetallic catalyst precursor obtained in the step (3) to obtain the final bimetallic catalyst Cu/Ce-UZM-9.

According to another embodiment of the application, a microporous molecular sieve type bimetallic AN tail gas removal catalyst is prepared by adopting a solid-phase ion exchange method, and the specific steps are as follows:

(3) Fully grinding and mixing NH ₄ -UZM-9 molecular sieve, cu salt and Ce salt, and then placing the mixture in a rotary tubular reaction furnace for solid-phase ion exchange to obtain a Cu/Ce-UZM-9 bimetallic catalyst precursor;

According to another embodiment of the application, a rotary evaporation ion exchange method is adopted to prepare a microporous molecular sieve type bimetallic AN tail gas removal catalyst, and the method comprises the following specific steps:

(3) Placing NH ₄ -UZM-9 molecular sieve, cu salt, ce salt and deionized water in a round bottom flask, stirring and mixing uniformly at room temperature, then carrying out rotary evaporation ion exchange at 35-70 ℃, drying the obtained material in a vacuum drying oven for 6-24h after evaporation, and obtaining a Cu/Ce-UZM-9 precursor at 70-100 ℃;

According to still another embodiment of the application, the microporous molecular sieve type bimetallic AN removal catalyst is prepared by adopting AN isovolumetric impregnation ion exchange method, and the specific steps are as follows:

(3) Uniformly mixing NH ₄ -UZM-9 molecular sieve with Cu salt and Ce salt water solution, and then drying in a vacuum drying oven for 6-24h at 70-100 ℃ to obtain Cu/Ce-UZM-9 catalyst precursor;

The Cu salt adopted by the invention is one of copper nitrate, copper chloride, copper acetate and copper sulfate, and the optimal choice is copper chloride.

The Ce ³⁺ metal salt adopted by the invention is one of cerium nitrate, ammonium cerium nitrate, cerium chloride and cerium sulfate, and the optimal choice is cerium nitrate.

The temperature adopted by the liquid phase ion exchange method is room temperature to 95 ℃, and the optimal temperature range is 60-90 ℃.

The concentration range of Cu salt in the liquid phase ion exchange method is 0.001mol/L-2.0mol/L, and the exchange times are 1-9 times. The optimal exchange concentration is 0.005-0.1mol/L, and the optimal exchange times are 2-6 times.

In the liquid phase ion exchange method, the concentration of Ce ³⁺ metal salt is 0.01-0.1mol/L, and the exchange times are 1-9 times. The optimal exchange concentration is 0.01-0.08mol/L, and the optimal exchange times are 2-6 times.

The temperature range adopted in the solid-phase ion exchange method is 200-400 ℃, and the optimal exchange temperature is 250-350 ℃.

The temperature range adopted in the rotary evaporation ion exchange method is 40-55 ℃, and the optimal temperature range is 45-50 ℃.

The roasting temperature adopted by the invention is 500-550 ℃.

Example 1:

2.1g of calcined Na-UZM-9,5.34g of NH ₄ Cl was placed in a 250ml three-necked flask, 100ml of H ₂ O was added thereto and stirred well. Then ion-exchanged for 4 hours in a water bath at 80 ℃, followed by centrifugal washing and drying at 100 ℃. The above process was repeated 3 times to ensure that the Na-UZM-9 molecular sieve was exchanged for NH ₄ -UZM-9 molecular sieve.

2GNH ₄-UZM-9,0.5gCuCl₂·2H₂ O was placed in a 250ml three-necked flask, and 100ml of H ₂ O was added thereto and stirred well. Then ion-exchanged for 4 hours in a water bath at 80 ℃, followed by centrifugal washing and drying at 100 ℃. The process is repeated for 5 times to obtain the Cu-UZM-9 molecular sieve catalyst precursor.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Cu-UZM-9 catalyst, which is marked as sample No. 1.

Example 2:

2GNH ₄-UZM-9,2gCe(NO₃)₃·6H₂ O was placed in a 250ml three-necked flask, and 100ml of H ₂ O was added thereto and stirred well. Then ion-exchanged for 4 hours in a water bath at 80 ℃, followed by centrifugal washing and drying at 100 ℃. Repeating the above process for 5 times to obtain the Ce-UZM-9 molecular sieve catalyst precursor.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Ce-UZM-9 catalyst, which is marked as sample No. 2.

Example 3:

2GNH ₄-UZM-9,0.5gCuCl₂·2H₂ O and 1.5gCe (NO ₃)₃·6H₂ O) are placed in a 250ml three-necked flask, 100ml of H ₂ O is added, and the mixture is stirred uniformly, then ion exchange is carried out for 4 hours under the water bath condition of 80 ℃, centrifugal washing is carried out, and drying is carried out at 100 ℃, and the process is repeated for 5 times to obtain the Cu/Ce-UZM-9 molecular sieve precursor.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Cu/Ce-UZM-9 catalyst, which is marked as sample No. 3.

Example 4:

Fully grinding and mixing 2gNH ₄ -UZM-9, 0.4gCuCl ₂·2H₂ O and 1.0gCe (NO ₃)₃·6H₂ O mortar), transferring into a rotary tubular reaction furnace for solid-phase ion exchange, heating to 300 ℃ at the speed of 10 ℃/min, and maintaining for 10 hours to obtain the Cu-Ce/UZM-9 precursor.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Cu/Ce-UZM-9 catalyst, which is marked as sample No. 4.

Example 5:

2GNH ₄-UZM-9,0.6gCuCl₂·2H₂ O and 2.5gCe (NO ₃)₃·6H₂ O is placed in a 500ml three-necked flask, 250ml of H ₂ O is added, and the mixture is stirred uniformly, then the mixture is subjected to ion exchange for 4 hours under the condition of rotary evaporation at 45 ℃, and then vacuum drying at 60 ℃ is carried out to obtain the Cu/Ce-UZM-9 molecular sieve catalyst precursor.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Cu/Ce-UZM-9 catalyst, which is marked as sample No. 5.

Example 6:

Mixing 0.54gCuCl ₂·2H₂O、3.4gCe(NO₃)₃·6H₂ O with 2.0g H ₂ O, stirring uniformly, adding 2gNH ₄ -UZM-9 molecular sieve into the above solution, stirring thoroughly, and drying in a vacuum drying oven at 60deg.C to obtain Cu/Ce-UZM-9 catalyst.

Then the precursor is placed in a muffle furnace for roasting for 4 hours at 500 ℃ to obtain a Cu/Ce-UZM-9 catalyst, which is marked as sample No. 6.

Example 7

The difference from example 3 is that 0.5gCuCl ₂·2H₂ O was replaced by 0.24gCu (NO ₃)₂; 1.5gCe (NO ₃)₃·6H₂ O was replaced by 1.2gCe (NH ₄)₂(NO₃)₆).

Example 8

The difference from example 3 is that 0.5gCuCl ₂·2H₂ O was substituted for 0.2g cu (CH ₃COO)₂, 1.5gCe (NO ₃)₃·6H₂ O was substituted for 0.83gCeCl ₃·7H₂ O).

EXAMPLE 9XRD testing

XRD tests were performed on samples 1# through 5# respectively, with the angle range of the XRD test being 5-50.

The test results are shown in fig. 1, and in the examples 1,3 and 4 in fig. 1, there are no characteristic diffraction peaks corresponding to metal oxides except diffraction peaks corresponding to typical a-type molecular sieves, which are mainly because the dispersibility of the metal oxides is good and is lower than the detection limit of XRD. Whereas, in the samples of example 2 and example 5, in addition to the diffraction peaks of the molecular sieve, characteristic peaks corresponding to CeO ₂ were present, which indicated that a portion of the added Ce species was present as metal oxide at the outer surface of the catalyst and generated aggregation.

Example 10 specific surface area test

Specific surface area tests are respectively carried out on samples 1# to 6# under the following test conditions: pretreating the sample for 8-12 h at 200-250 ℃, and then analyzing by using liquid argon as a medium.

The test result shows that the specific surface area of the samples 3# to 6# is 250 m ²/g to 500m ²/g;

As represented typically by sample 3# and the test results are shown in fig. 2, it can be seen that the sample has a high specific surface area and that a certain amount of mesoporous structure is generated in the sample after ion exchange.

Example 11AN removal evaluation test

AN removal evaluation tests are respectively carried out on samples 1# to 6# under the following evaluation conditions: AN 450ppm, O ₂ 5vol％,H₂O 3vol％,N₂ as balance gas, airspeed of 100,000h ^-1 and test temperature range of 150-550 ℃.

The test results are shown in fig. 3 to 5:

as can be seen from fig. 3, samples 3# to 6# have good AN removal activity, and can completely convert AN at 270 ℃;

as can be seen from fig. 4 and 5, the selectivity of CO ₂ was maintained at almost 100% and the selectivity of N ₂ was maintained at 90% or more over a wide temperature range (150-550 ℃), showing excellent product selectivity. The nitrogen selectivity of examples 1 and 2 was also higher, since the addition of Ce on the basis of example 1 enhanced the redox performance of the catalyst and thus increased the activation activity of AN, but too high redox performance had AN opposite effect on the selectivity of N ₂, so the nitrogen selectivity was relatively slightly reduced (relative to example 1), but maintained at 90% or more.

Example 12H ₂ -TPR test

H ₂ -TPR test is carried out on samples No. 1-No. 6 respectively, wherein the test instrument is CHEMBET 3000; the test conditions were: the sample was first treated at 500℃for 2 hours, then cooled to room temperature and a 10% H ₂/Ar mixture was introduced, and the temperature was increased from 25℃to 700℃at 10 min/. Degree..

The test results are shown in fig. 6, which shows that adding Ce species on the basis of Cu species can improve the redox performance of Cu species, thereby improving the activity of the catalyst.

Example 13XPS test

Sample 1# and 3-6# were subjected to the Cu 2pXPS test under the following conditions: the excitation source was an aluminum source, vacuum treatment was performed before the test, and the resulting binding energy was corrected with C1s (284.8 eV).

As shown in fig. 7, under the condition that the Cu content is the same (in examples 3 to 6, the Cu content is 6.5 wt%), increasing the Ce content can help the Cu species migrate to the outer surface of the crystal, thereby reducing the diffusion path of the reactant, and increasing the probability of the reactant contacting the active site, thereby improving the activity of the catalyst.

While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims

1. A method for removing acrylonitrile is characterized in that,

Contacting a gas containing acrylonitrile with a bimetallic molecular sieve catalyst to remove the acrylonitrile;

the bimetallic molecular sieve catalyst comprises a carrier framework and metal elements loaded on the carrier framework;

The carrier framework comprises an NH ₄ -UZM-9 molecular sieve;

The metal element comprises Cu element and Ce element;

Wherein the Cu element is an active center; the Ce element is an auxiliary agent;

The bimetallic molecular sieve catalyst is prepared by the following steps:

s200) roasting the precursor to obtain a bimetallic molecular sieve catalyst;

the metal sources are a Cu source and a Ce source.

2. The method of claim 1, wherein the step of determining the position of the substrate comprises,

The Cu source is Cu salt;

the Cu salt comprises at least one of copper nitrate, copper chloride, copper acetate and copper sulfate;

The Ce source is Ce salt;

3. The method of claim 1, wherein the step of determining the position of the substrate comprises,

In step S100), the load is selected from any one of a liquid phase ion exchange system, a solid phase ion exchange system, and an isovolumetric impregnation system.

4. The method of claim 1, wherein the step of determining the position of the substrate comprises,

Said step S100) comprises the steps of:

5. The method of claim 4, wherein the step of determining the position of the first electrode is performed,

In the step S100-1), the concentration of Cu salt in the aqueous solution is 0.001-5.0 mol/L;

The concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L;

6. The method of claim 1, wherein the step of determining the position of the substrate comprises,

Said step S100) comprises the steps of:

7. The method of claim 6, wherein the step of providing the first layer comprises,

In the step S100-2), the mass percentage of the Cu salt in the solid phase mixture is 5-10wt%;

the mass percentage of the Ce salt in the solid phase mixture is 50-70 wt%;

The mass percentage of the NH ₄ -UZM-9 molecular sieve in the solid phase mixture is 30-40 wt%.

8. The method of claim 1, wherein the step of determining the position of the substrate comprises,

Said step S100) comprises the steps of:

9. The method of claim 8, wherein the step of determining the position of the first electrode is performed,

In the step S100-3), the concentration of Cu salt in the aqueous solution is 0.001-5.0 mol/L;

The concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L;

10. The method of claim 1, wherein the step of determining the position of the substrate comprises,

Said step S100) comprises the steps of:

11. The method of claim 10, wherein the step of determining the position of the first electrode is performed,

In the step S100-4), the concentration of Cu salt in the aqueous solution is 0.001-5.0 mol/L;

The concentration of Ce salt in the aqueous solution is 0.01-3.0 mol/L;

12. The method of claim 1, wherein the step of determining the position of the substrate comprises,

The loading amount of the Cu element in the bimetallic molecular sieve catalyst is 1-12 wt%;

the loading of the Ce element in the bimetallic molecular sieve catalyst is 1-70wt%.