CN118950067A

CN118950067A - Silicon-based ammonia cracking hydrogen production catalyst and preparation method and application thereof

Info

Publication number: CN118950067A
Application number: CN202411435547.4A
Authority: CN
Inventors: 李振国; 刘亚涛; 邵元凯; 李凯祥; 任晓宁; 方茂东; 杨正军; 吴撼明; 周冰洁; 董安琪; 祝伟康; 尹硕尧; 刘习; 吕诚
Original assignee: China Automotive Technology and Research Center Co Ltd; CATARC Automotive Test Center Tianjin Co Ltd
Current assignee: China Automotive Technology and Research Center Co Ltd; CATARC Automotive Test Center Tianjin Co Ltd
Priority date: 2024-10-15
Filing date: 2024-10-15
Publication date: 2024-11-15
Anticipated expiration: 2044-10-15
Also published as: CN118950067B

Abstract

The application relates to the field of catalysts, and particularly provides a silicon-based ammonia cracking hydrogen production catalyst, and a preparation method and application thereof. The catalyst for preparing hydrogen by silicon-based ammonia pyrolysis comprises a silicon-based carrier, an active component and a modifying additive; the silicon-based carrier comprises silicon nitride, silicon carbide, silicon molybdenum powder, diatomite, pure silicon molecular sieve, silicon dioxide or SAB-16; the active component comprises at least one of Ru, co, mo, fe; the modifying aid comprises at least one of Li, na, K, cs, rb, ba, ir. The catalyst of the application has NH ₃ conversion rate of more than 80% under 12000 mL-g ^‑1·h^‑1 and 500 ℃ and basically has no byproduct generation; the problem of hydrogen embrittlement of the traditional ammonia cracking material carrier is effectively solved; also has high oxidation resistance, and does not react with oxygen in a dry atmosphere below 800 ℃.

Description

Silicon-based ammonia cracking hydrogen production catalyst and preparation method and application thereof

Technical Field

The application relates to the field of catalysts, in particular to a silicon-based catalyst for producing hydrogen by ammonia cracking, and a preparation method and application thereof.

Background

Hydrogen is considered as the most ideal clean energy source, and research and practice in the automotive field is well-developed, and future automotive hydrogen power is considered to be promising new automotive power, especially for heavy trucks. However, limited by molecular physicochemical properties, there are significant safety risks in the storage, transport and use of hydrogen. The ammonia gas with stable property, wide source and mature industry is used as the hydrogen storage carrier, and is one of the technical approaches for solving the bottleneck of large-scale application of hydrogen energy in recent years. While the ammonia cracking hydrogen production reaction is an endothermic reaction, and is usually carried out at a higher temperature, the current catalyst is still insufficient in terms of reducing the reaction temperature and reducing the hydrogen embrittlement.

In view of this, the present application has been made.

Disclosure of Invention

The application aims to provide a silicon-based ammonia cracking hydrogen production catalyst and a preparation method and application thereof, so as to solve the problems of high catalytic reaction temperature and easy hydrogen embrittlement in the prior art.

In order to achieve the above object of the present application, the following technical solutions are specifically adopted:

In a first aspect, the application provides a catalyst for producing hydrogen by silicon-based ammonia pyrolysis, which comprises a silicon-based carrier, an active component and a modifying additive;

the silicon-based carrier comprises silicon nitride, silicon carbide, silicon molybdenum powder, diatomite, pure silicon molecular sieve, silicon dioxide or SAB-16;

the active component comprises at least one of Ru, co, mo, fe;

The modifying aid comprises at least one of Li, na, K, cs, rb, ba, ir.

As a further preferable technical scheme, the loading amount of the active component is 1-10 wt%.

As a further preferable technical scheme, the loading amount of the modifying auxiliary agent is 0.2-5 wt%.

In a second aspect, the application provides a preparation method of the catalyst for producing hydrogen by cracking silicon-based ammonia, which comprises the following steps:

dissolving a precursor of an active component in water, then adding a precursor of a modifying auxiliary agent, and performing ultrasonic dispersion to obtain a first solution;

And mixing the first solution with a silicon-based carrier, heating and stirring, and drying and calcining to obtain the catalyst.

As a further preferable technical scheme, the ultrasonic dispersion time is 0.5-1.5 h.

As a further preferable technical scheme, the temperature of heating and stirring is 60-180 ℃ and the stirring time is 2-10 h.

As a further preferable technical scheme, the drying temperature is 40-120 ℃ and the drying time is 10-14 h.

As a further preferable technical scheme, the calcination atmosphere is an ammonia atmosphere, the calcination temperature is 450-550 ℃, and the calcination time is 2-6 h.

In a third aspect, the application provides a catalyst for producing hydrogen by ammonia cracking of silicon-based or application of the catalyst for producing hydrogen by ammonia cracking of silicon-based prepared by the preparation method in producing hydrogen by ammonia cracking.

Compared with the prior art, the application has the beneficial effects that:

The catalyst for preparing hydrogen by ammonia cracking of silicon-based provided by the application comprises a specific silicon-based carrier, a specific active component and a specific modification auxiliary agent, wherein the silicon-based carrier has a high specific surface area, the active component and the modification auxiliary agent are loaded, the catalytic reaction temperature of hydrogen preparation by ammonia cracking can be effectively reduced, the yield of H ₂ is improved, the service life of the catalyst is prolonged, the NH ₃ conversion rate is more than 80% under the conditions of 12000mL & g ^-1·h^-1 and 500 ℃, and no by-product is basically generated; the carrier does not contain metal elements, so that the problem of hydrogen embrittlement of the traditional metal carrier is effectively solved; the silicon-based carrier can provide good thermal stability, which is particularly important for high-temperature reaction such as ammonia cracking, the stability of the catalyst directly influences the service life of the catalyst and the sustainability of the reaction at high temperature, and the catalyst also has higher oxidation resistance and does not react with oxygen in a dry atmosphere below 800 ℃.

Drawings

FIG. 1 is a SEM image of a catalyst for producing hydrogen by cracking silicon-based ammonia in example 8;

FIG. 2 is a SEM image of a catalyst for producing hydrogen by cracking silicon-based ammonia in example 8.

Detailed Description

Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer.

According to one aspect of the application, the application provides a catalyst for producing hydrogen by silicon-based ammonia cracking, which comprises a silicon-based carrier, an active component and a modifying additive;

the active component comprises at least one of Ru, co, mo, fe;

The modifying aid comprises at least one of Li, na, K, cs, rb, ba, ir.

Wherein the silicon-molybdenum powder refers to mixed powder of silicon and molybdenum. Pure silicon molecular sieves refer to molecular sieves consisting of silicon only. SAB-16 is a mesoporous material belonging to one of SBA (Santa Barbara Amorphous) series of materials. The materials generally have regular pore canal structures, high specific surface area, good thermal stability and chemical stability, so that the materials have wide application in the fields of catalysis, adsorption, separation and the like. The SAB-16 material has the characteristics of cubic phase structure, contribution to rapid diffusion of reaction molecules and abundant silicon hydroxyl groups, and can be subjected to surface modification through silanization reaction so as to adjust the surface properties and functions.

Active components in the present application include, but are not limited to: ru, co, mo, fe, ru and Co, co and Mo, mo and Fe, mo and Ru, ru and Fe, ru, co and Fe, co, mo and Fe, or Ru, co, mo and Fe, etc.

The modifying aids in the present application include, but are not limited to: li, na, K, cs, rb, ba, ir, li and Na, na and K, K and Cs, cs and Rb, li, na and K, K, cs and Rb, cs, rb and Ba, rb, ba and Ir, li, na, K and Cs, na, K, cs and Rb, cs, rb, ba and Ir, li, na, K, cs and Rb, K, cs, rb, ba and Ir, li, na, K, cs, rb and Ba, na, K, cs, rb, ba and Ir, or Li, na, K, cs, rb, ba and Ir, etc.

The catalyst for preparing hydrogen by ammonia cracking of silicon-based comprises a specific silicon-based carrier, a specific active component and a specific modification auxiliary agent, wherein the silicon-based carrier has high specific surface area, the catalytic reaction temperature of hydrogen preparation by ammonia cracking can be effectively reduced by loading the active component and the modification auxiliary agent, the H ₂ yield is improved, the service life of the catalyst is prolonged, the NH ₃ conversion rate is more than 80% under the conditions of 12000mL & g ^-1·h^-1 and 500 ℃, and no by-product is basically generated; the problem of hydrogen embrittlement of the traditional ammonia cracking material carrier is effectively solved; also has high oxidation resistance, and does not react with oxygen in a dry atmosphere below 800 ℃.

In an alternative embodiment, the active component is present at a loading of 1wt% to 10wt%. The loading of the active component includes, but is not limited to, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 10wt%. Experiments prove that when the loading of the active components is in the range, the obtained catalyst has better comprehensive performance. The active component loading influences the performance of the catalyst by adjusting the dispersibility of the metal elements and the interval between the metal elements.

In an alternative embodiment, the loading of the modifying aid is 0.2wt% to 5wt%. The loading of the above-mentioned modifying auxiliary includes, but is not limited to, 0.2wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%. The modifying aid adjusts the performance of the catalyst by being able to alter the electronic properties of the catalyst. Preferably, the loading of the modifying auxiliary agent is 4-5 wt%.

The load in the application refers to the weight percentage of the active component or the modifying auxiliary agent in the silicon-based carrier.

According to another aspect of the application, the application provides a preparation method of the catalyst for producing hydrogen by silicon-based ammonia cracking, which comprises the following steps:

The method is used for preparing the catalyst for preparing the hydrogen by the silicon-based ammonia pyrolysis, the preparation process is simple, the cost is low, the promotion is easy, and the prepared catalyst for preparing the hydrogen by the silicon-based ammonia pyrolysis has good catalytic performance.

Alternatively, the precursor of the active ingredient and the precursor of the modifying auxiliary are each independently a soluble salt thereof, such as a halide or the like.

In an alternative embodiment, the time of the ultrasonic dispersion is 0.5 to 1.5 hours. The above time of ultrasonic dispersion includes, but is not limited to, 0.5h,1h or 1.5h. The ultrasonic dispersion treatment mainly improves the dispersibility of the active components and the modification auxiliary agent, the ultrasonic time is generally selected to be 0.5-1h, and the influence of the ultrasonic time on the performance of the catalyst is further reduced.

In an alternative embodiment, the temperature of heating and stirring is 60-180 ℃, and the stirring time is 2-10 h. The temperature of the heating and stirring includes, but is not limited to, 60 ℃, 70 ℃, 80 ℃,90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃ or 180 ℃. Such agitation times include, but are not limited to, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h. The stirring temperature mainly ensures that the catalyst is mixed more uniformly, and the reaction can be completed more quickly by increasing the temperature; the longer the stirring time is theoretically, the better, but in consideration of time cost, 2 to 10 hours, preferably 3 to 6 hours, are generally selected.

In an alternative embodiment, the drying temperature is 40-120 ℃ and the drying time is 10-14 h. The temperature of the above drying includes, but is not limited to, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, or 120 ℃. The drying time includes, but is not limited to, 10h, 11h, 12h, 13h, or 14h. The lower the drying temperature is, the better, but the drying time increases; the drying temperature is too high, and the evaporation rate of water is higher, so that the active components and the modifying auxiliary agent can be driven to migrate to the surface of the catalyst, the dispersion of the active components and the modifying auxiliary agent is not facilitated, and the drying temperature is generally 40-120 ℃, preferably 80-100 ℃.

Optionally, the method further comprises the steps of filtering and washing 3-5 times before drying so as to remove impurity components and improve the target object ratio.

In an alternative embodiment, the calcination atmosphere is an ammonia atmosphere, the calcination temperature is 450-550 ℃, and the calcination time is 2-6 hours. The calcination temperature includes, but is not limited to, 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, or 550 ℃. The calcination time includes, but is not limited to, 2h, 3h, 4h, 5h, or 6h. Too low a calcination temperature to form the desired compound may cause sintering of the catalyst or volatilization of the active components, typically 450-550 c, preferably 500-550 c, most preferably 500 c.

According to another aspect of the application, the application also provides the silicon-based ammonia cracking hydrogen production catalyst or application of the silicon-based ammonia cracking hydrogen production catalyst prepared by the preparation method in ammonia cracking hydrogen production. The catalyst for preparing hydrogen by ammonia cracking of silicon base is applied to preparing hydrogen by ammonia cracking, can obviously reduce reaction temperature, reduce energy consumption, reduce the generation of byproducts and avoid the problem of hydrogen embrittlement.

The present application will be described in further detail with reference to examples and comparative examples.

Example 1

A catalyst for preparing hydrogen by cracking silicon-based ammonia comprises a silicon-based carrier, an active component and a modifying additive;

The silicon-based carrier is silicon nitride; the active component is Ru; the modifying auxiliary agent is Li.

The loading of the active component is 12wt% and the loading of the modifying assistant is 6wt%.

The catalyst for preparing hydrogen by silicon-based ammonia pyrolysis is prepared by the following method: and mixing the precursor of the active component, the precursor of the modifying additive, water and the silicon-based carrier together, heating and stirring, and drying and calcining to obtain the catalyst. Wherein the temperature of heating and stirring is 90 ℃, and the stirring time is 10 hours; the drying temperature is 100 ℃ and the drying time is 12 hours; the calcination atmosphere is ammonia gas atmosphere, the calcination temperature is 500 ℃, and the calcination time is 5h.

Examples 2 to 4

Unlike example 1, the active components of examples 2 to 4 were supported at 1wt%, 5wt% and 10wt% respectively, and the remainder was the same as example 1.

Examples 5 to 7

Unlike example 4, the modified auxiliaries in examples 5 to 7 were supported in amounts of 0.2wt%, 3wt% and 5wt%, respectively, and the remainder was the same as in example 4.

Example 8

Unlike example 7, the preparation method of the catalyst in this example is: dissolving a precursor of an active component in water, then adding a precursor of a modifying auxiliary agent, and performing ultrasonic dispersion to obtain a first solution; and mixing the first solution with a silicon-based carrier, heating and stirring, and drying and calcining to obtain the catalyst. The time of ultrasonic dispersion was 1h. The remainder was the same as in example 7.

Examples 9 to 12

Unlike example 8, the ultrasonic dispersion times in examples 9-12 were 0.2h, 0.5h, 1.5h, and 2h, respectively. The remainder was the same as in example 8.

Example 13

Unlike example 8, the temperature of heating and stirring in this example was 60℃and the stirring time was 10 hours. The remainder was the same as in example 8.

Example 14

Unlike example 8, the temperature of heating and stirring in this example was 180℃and the stirring time was 2 hours. The remainder was the same as in example 8.

Example 15

Unlike example 8, the drying temperature in this example was 40℃and the drying time was 14 hours. The remainder was the same as in example 8.

Example 16

Unlike example 8, the drying temperature in this example was 120℃and the drying time was 10 hours. The remainder was the same as in example 8.

Example 17

Unlike example 8, the calcination temperature in this example was 450℃and the calcination time was 6 hours. The remainder was the same as in example 8.

Example 18

Unlike example 8, the calcination temperature in this example was 550℃and the calcination time was 2 hours. The remainder was the same as in example 8.

Example 19

Unlike example 8, the silicon-based catalyst for producing hydrogen by ammonia cracking is characterized in that the silicon-based carrier in this example is silicon-molybdenum powder, the active component is Co, and the modifying auxiliary agent is Cs. The remainder was the same as in example 8.

Example 20

Unlike example 8, the silicon-based catalyst for producing hydrogen by ammonia cracking is characterized in that the silicon-based carrier in this example is a pure silicon molecular sieve, the active component is Fe, and the modifying auxiliary agent is Ir. The remainder was the same as in example 8.

Example 21

Unlike example 8, the silicon-based carrier in this example is silicon dioxide, the active components are Ru and Co (weight ratio is 1:1), and the modifying auxiliary agent is K and Rb (weight ratio is 1:1). The remainder was the same as in example 8.

Example 22

Unlike example 8, the silicon-based ammonia cracking hydrogen production catalyst in this example has silicon carbide as the silicon-based carrier, co, mo and Fe as the active components in the weight ratio of 1 to 1, and Na, ba and Ir as the modifying assistant in the weight ratio of 1 to 1. The remainder was the same as in example 8.

FIGS. 1-2 are SEM images of a catalyst for producing hydrogen by ammonia cracking of silicon-based ammonia in example 8, and it can be seen from the drawings that metallic elements are dispersed on the surface of the catalyst without forming large agglomerates.

Comparative example 1

A catalyst for preparing hydrogen by cracking silicon-based ammonia comprises a silicon-based carrier and an active component, wherein the silicon-based carrier is silicon dioxide, the active component is Ni, and the loading amount of Ni is 12wt%. The preparation method is similar to that of the embodiment 1 of the present application, and is not repeated here.

Comparative example 2

A catalyst for preparing hydrogen by cracking silicon-based ammonia comprises a silicon-based carrier and an active component, wherein the silicon-based carrier is silicon nitride, the active component is Ru, and the load of Ru is 12wt%. The preparation method is similar to that of the embodiment 1 of the present application, and is not repeated here.

Comparative example 3

A catalyst for preparing hydrogen by cracking silicon-based ammonia comprises a silicon-based carrier and a modifying additive, wherein the silicon-based carrier is silicon nitride, the modifying additive is Li, and the loading amount of Li is 6wt%. The preparation method is similar to that of the embodiment 1 of the present application, and is not repeated here.

The above catalysts were all powder, and the silicon-based ammonia cracking hydrogen production catalysts in the above examples and comparative examples were tested: sieving the powder to be tested with a 40-60 mesh sieve, tabletting, and loading 1g of catalyst into the center of a quartz tube with quartz cotton. The gas was switched to NH ₃/N₂, and then the catalyst bed was adjusted to the target reaction temperature and the gas composition and content changes were analyzed by equipped mass spectrometry. The following table shows the NH ₃ conversion at 500℃for each example and each comparative example.

While particular embodiments of the present application have been illustrated and described, it will be appreciated that various other changes and modifications can be made without departing from the spirit and scope of the application. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this application.

Claims

1. A silicon-based ammonia cracking hydrogen production catalyst, characterized in that it comprises a silicon-based carrier, an active component and a modification aid;

The silicon-based carrier includes silicon nitride, silicon carbide, silicon molybdenum powder, diatomaceous earth, pure silicon molecular sieve, silicon dioxide or SAB-16;

The active component includes at least one of Ru, Co, Mo and Fe;

The modification aid includes at least one of Li, Na, K, Cs, Rb, Ba, and Ir.

2. The silicon-based ammonia cracking catalyst for hydrogen production according to claim 1, characterized in that the loading amount of the active component is 1wt%~10wt%.

3. The silicon-based ammonia cracking catalyst for hydrogen production according to claim 1 or 2, characterized in that the loading amount of the modification aid is 0.2wt%~5wt%.

4. The method for preparing the silicon-based ammonia cracking hydrogen production catalyst according to any one of claims 1 to 3, characterized in that it comprises the following steps:

Dissolving the precursor of the active component in water, then adding the precursor of the modifying auxiliary agent, and dispersing by ultrasonication to obtain a first solution;

The first solution is mixed with a silicon-based carrier, heated and stirred, and then dried and calcined to obtain the catalyst.

5. The method for preparing a silicon-based ammonia cracking catalyst for hydrogen production according to claim 4, characterized in that the ultrasonic dispersion time is 0.5 to 1.5 hours.

6. The method for preparing a silicon-based ammonia cracking catalyst for hydrogen production according to claim 4, characterized in that the heating and stirring temperature is 60°C to 180°C, and the stirring time is 2 to 10 hours.

7. The method for preparing a silicon-based ammonia cracking catalyst for hydrogen production according to claim 4, characterized in that the drying temperature is 40-120°C and the drying time is 10-14 hours.

8. The method for preparing a silicon-based ammonia cracking catalyst for hydrogen production according to any one of claims 4 to 7, characterized in that the calcination atmosphere is an ammonia atmosphere, the calcination temperature is 450 to 550°C, and the calcination time is 2 to 6 hours.

9. Use of the silicon-based ammonia cracking hydrogen production catalyst according to any one of claims 1 to 3 or the silicon-based ammonia cracking hydrogen production catalyst prepared by the preparation method according to any one of claims 4 to 8 in ammonia cracking hydrogen production.