A method for hydrogen production by electrically assisted low-temperature ammonia decomposition

Abstract

The application belongs to the technical field of hydrogen production by ammonia decomposition, and discloses an electrically-assisted low-temperature hydrogen production method by ammonia decomposition, characterized by comprising the following steps: S1, preparing a reactor; the reactor comprises a quartz tube, two pieces of foam copper are installed in the quartz tube, a catalyst is filled between the two pieces of foam copper, each piece of foam copper is connected with a copper electrode, and two thermocouples are installed in the quartz tube and extend into the catalyst; S2, preparing the catalyst; S2.1, the catalyst is synthesized by a solution combustion method, and the precursors of the components of the catalyst are respectively Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O; and S3, introducing ammonia into the reactor to produce hydrogen; compared with the prior art, the application applies the electric field-assisted catalysis technology to the field of hydrogen production by ammonia decomposition, and develops a catalyst suitable for the electric field-assisted hydrogen production by ammonia decomposition.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by ammonia decomposition, and particularly relates to an electrically assisted low-temperature ammonia decomposition method for hydrogen production. BACKGROUND

[0002] Hydrogen is the main product of energy, which is water, and will not produce pollutants or greenhouse gases in combustion or oxidation reactions, and is considered to be the ultimate energy of human society. However, the difficulty in storage and transportation limits its large-scale application. Ammonia is a very good hydrogen storage medium, with a hydrogen storage density of 17.8wt%, and the storage and transportation of ammonia have very complete infrastructure.

[0003] However, catalytic ammonia decomposition to produce hydrogen usually requires a high temperature (> 400℃), and the stability of the catalyst at high temperature is difficult to guarantee, and the energy consumption is high. Further, in some application scenarios, it is difficult to provide a heating environment, and thus it is difficult to catalyze ammonia decomposition to produce hydrogen. Therefore, the present application is committed to using electric field assisted catalysis technology to make ammonia reach a high decomposition conversion rate at low temperature or without external heating source. SUMMARY

[0004] In view of the problems in the above background art, the purpose of the present application is to provide an electrically assisted low-temperature ammonia decomposition method for hydrogen production.

[0005] To achieve the above technical purpose, the technical scheme adopted by the present application is as follows:

[0006] An electrically assisted low-temperature ammonia decomposition method for hydrogen production, characterized in that it comprises the following steps:

[0007] S1, preparing a reactor;

[0008] The reactor comprises a quartz tube, two pieces of foam copper are installed in the quartz tube, a catalyst is filled between the two pieces of foam copper, one copper electrode is connected to each of the two pieces of foam copper, and two thermocouples are installed in the quartz tube and extend into the catalyst;

[0009] S2, preparing the catalyst;

[0010] S2.1, the catalyst is synthesized by a solution combustion method, and each component precursor of the catalyst is Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O;

[0011] S2.2, the precursors and glycine are dissolved in 100ml of deionized water and stirred thoroughly;

[0012] S2.3, the stirring liquid is transferred to a muffle furnace, preheated at a temperature of 400 DEG C for 20 min, then heated to 600 DEG C and calcined for 4h to obtain the catalyst;

[0013] S3, hydrogen is prepared by introducing ammonia gas into the reactor.

[0014] Further limited, in step S2.3, the semiconductor SiC is doped into the obtained catalyst by a fixed grinding method, and the specific steps are as follows:

[0015] S2.3.1, Ru is loaded on the CeO2 carrier by the impregnation method, and calcination is carried out with a loading amount of 1%, to obtain a Ru / CeO2 catalyst;

[0016] S2.3.2, the Ru / CeO2 catalyst and nano SiC are mixed and ground under pressure in a mass fraction ratio of 3:1;

[0017] S2.3.3, the ground sample is tabletted under a pressure of 15Mpa;

[0018] Although the semiconductor oxide catalyst can realize the electric field assisted ammonia decomposition hydrogen production under low temperature conditions, it still needs an external heat source to heat the catalyst to the active temperature, and under the condition of no external heat source, arc discharge is easy to occur, and then the catalyst is burned out, and the addition of SiC can make the catalyst bear a stable electric field under the condition of no external heat source, so that the electric field assisted ammonia decomposition hydrogen production is separated from the limitation of external heat source, and then the application scene of the electric field assisted ammonia decomposition hydrogen production is expanded.

[0019] Further limited, in step S2.2, the stirring time is 2h, which ensures sufficient stirring effect.

[0020] Further limited, in step S2.3, the heating efficiency is 5 DEG C / min, and the stable step-by-step heating prevents the damage of the organization.

[0021] Further limited, in step S2.3, the doping amount of Ce is represented by the ratio of Ce and Zr, and the ratio of Ce and Zr is set to 0.25:0.75, and the proportion of active components Ni, Co and Fe is 10wt%, which is the most suitable amount and has good use effect.

[0022] The beneficial effects of the present application are as follows:

[0023] 1. Compared with the prior art, the electric field assisted catalysis technology is applied to the field of ammonia decomposition hydrogen production, and a catalyst suitable for electric field assisted ammonia decomposition hydrogen production is developed.

[0024] 2. The present application expands the temperature window of the traditional electric field assisted catalysis technology and breaks away from the limitation of external heat source. BRIEF DESCRIPTION OF DRAWINGS

[0025] The application can be further illustrated by the non-limiting examples shown in the accompanying drawings;

[0026] Figure 1 The reactor structure schematic diagram of an embodiment of the application of an electrically assisted low-temperature ammonia decomposition hydrogen production method;

[0027] The main element symbol is explained as follows:

[0028] Quartz tube 1; Foam copper 2; Catalyst 3; Copper electrode 4; Thermocouple 5. DETAILED DESCRIPTION

[0029] In order for those skilled in the art to better understand the application, the technical solutions of the application are further described below in combination with the drawings and examples.

[0030] As shown in the drawings, Figure 1 An electrically assisted low-temperature ammonia decomposition hydrogen production method of the application includes the following steps:

[0031] S1, preparing a reactor;

[0032] The reactor includes a quartz tube 1, two pieces of foam copper 2 are installed in the quartz tube 1, a catalyst 3 is filled between the two pieces of foam copper 2, each piece of foam copper 2 is connected with a copper electrode 4, and two thermocouples 5 are installed in the quartz tube 1 and extend into the catalyst 3;

[0033] S2, preparing the catalyst 3;

[0034] S2.1, the catalyst 3 is synthesized by a solution combustion method, and the precursors of each component of the catalyst 3 are respectively: Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O;

[0035] S2.2, the precursors and glycine are dissolved in 100 ml of deionized water and stirred thoroughly;

[0036] S2.3, the stirring solution is transferred to a muffle furnace, preheated at a temperature of 400°C for 20 min, then heated to 600°C and calcined for 4 h to obtain the catalyst 3;

[0037] S3, introducing ammonia into the reactor to produce hydrogen,

[0038] Preferably in step S2.3, a semiconductor SiC is doped into the obtained catalyst 3 by a fixed grinding method, and the specific steps are as follows:

[0039] S2.3.1, Ru is loaded on a CeO2 carrier by an impregnation method, and calcined at a loading amount of 1% to obtain a Ru / CeO2 catalyst;

[0040] S2.3.2, the Ru / CeO2 catalyst and nano-SiC are mixed and ground in a ratio of 3:1 by mass fraction under pressure;

[0041] S2.3.3, the ground sample is tabletted under a pressure of 15Mpa;

[0042] Although the semiconductor oxide catalyst can achieve electric field assisted ammonia decomposition for hydrogen production under low temperature conditions, it still needs an external heat source to heat the catalyst to an active temperature. Without an external heat source, electric arc discharge is easy to occur, which in turn burns the catalyst. The addition of SiC can enable the catalyst to withstand a stable electric field without an external heat source, making the electric field assisted ammonia decomposition for hydrogen production independent of external heat sources, thereby expanding the application scenarios of electric field assisted ammonia decomposition for hydrogen production. In fact, the doping method of SiC can also be considered according to the specific circumstances.

[0043] Preferably, in step S2.2, the stirring time is 2h, which ensures sufficient stirring effect. In fact, the stirring time can also be considered according to the specific circumstances.

[0044] Preferably, in step S2.3, the heating efficiency is 5℃ / min, which stabilizes the gradual heating and prevents tissue damage. In fact, the heating efficiency can also be considered according to the specific circumstances.

[0045] Preferably, in step S2.3, the doping amount of Ce is represented by the ratio of Ce to Zr, and the ratio of Ce to Zr is set to 0.25:0.75. The proportion of active components Ni, Co and Fe is 10wt%, which is the most suitable amount and has good use effect. In fact, the doping amount of Ce can also be considered according to the specific circumstances.

[0046] In this embodiment, the reactor temperature is determined by the ammonia inlet thermocouple 5 and the middle thermocouple 5 in the catalyst 3 bed. Two copper electrodes 4 are fixed at both ends of the reactor, one copper electrode 4 is connected to a high-voltage direct-current power supply, and the other copper electrode 4 is connected to the ground. A piece of foam copper 4 is placed between the electrode and the catalyst 3 bed to reduce the contact resistance;

[0047] According to the statistical results of existing literature, under thermal catalytic conditions, 300℃ is considered to be the active temperature of ammonia decomposition catalyst, and the ammonia decomposition conversion rate is less than 10%. When the temperature is 350℃, the ammonia decomposition conversion rate is less than 30%. Thereafter, the ammonia decomposition conversion rate increases rapidly with temperature. Therefore, 350℃ is taken as the low temperature condition of the present patent.

[0048] Example one: the low temperature condition directly uses a semiconductor oxide catalyst, i.e. the catalyst 3. Such catalyst has strong synergistic effect with electric field under low temperature condition, and can obtain high activity,

[0049] The results of the electric field catalysis experiment are shown in the table (Note: the suffix EF of the catalyst indicates the electric field condition, space velocity 4000 mL / (gcat h), power 1-5 W);

[0050]

[0051] As can be seen from the table, under the condition of a furnace temperature of 250°C, Ni / Ce 0.25 Zr 0.75 O2, Ni / Ce 0.2 Zr 0.8 O2, Ni / Ce 0.16 Zr 0.84 O2, and Co / Ce 0.25 Zr 0.75 O2all have high conversion rates, that is, it is concluded that catalyst 3 has a strong synergistic effect with the electric field under low temperature conditions, and can obtain high activity;

[0052] Example 2: Electric field assisted ammonia decomposition without an external heat source;

[0053] Although the semiconductor oxide catalyst can achieve electric field assisted ammonia decomposition for hydrogen production under low temperature conditions, it still needs an external heat source to heat the catalyst to an active temperature, and under the condition of no external heat source, electric arc discharge is easy to occur, and the catalyst is further burned out. In order to expand the application scenarios of electric field assisted ammonia decomposition for hydrogen production, a third generation semiconductor SiC is doped in the original catalytic system. The addition of SiC can enable the catalyst to bear a stable electric field under the condition of no external heat source, so that the electric field assisted ammonia decomposition for hydrogen production is free from the restriction of external heat source;

[0054] The results of the electric field catalysis experiment are shown in the table (space velocity 12000 mL / (gcat h));

[0055]

[0056]

[0057] As can be seen from the table, electric field assisted ammonia decomposition without an external heat source can achieve conversion, and with the increase of power, the conversion rate is improved. In the thermal catalytic scene, the conversion rate is further improved, and when the temperature is close to 600°C, the conversion rate can reach 100%.

[0058] The above examples only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for producing hydrogen by an electrically-assisted low-temperature ammonia decomposition, characterized by, It comprises the following steps: S1, preparing a reactor; The reactor comprises a quartz tube (1) in which two pieces of foam copper (2) are installed, the two pieces of foam copper (2) are filled with a catalyst (3), and the two pieces of foam copper (2) are respectively connected with a copper electrode (4). Two thermocouples (5) are installed in the quartz tube (1) and extend into the catalyst (3); S2, preparing the catalyst (3); S2.1, the catalyst (3) is synthesized by solution combustion method, and the precursors of each component of the catalyst (3) are respectively: Ni(NO3)2·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O; S2.2, dissolve the precursors and glycine in 100ml deionized water and stir thoroughly; S2.3, transfer the stirring solution to a muffle furnace, preheat at 400℃ for 20min, then heat to 600℃ and calcine for 4h to obtain the catalyst (3); S3, hydrogen production by introducing ammonia into the reactor; In step S2.3, semiconductor SiC is doped into the obtained catalyst (3) by fixed grinding method, and the specific steps are as follows: S2.3.1, load Ru on the CeO2 carrier by impregnation method, calcine at a loading amount of 1%, and obtain Ru / CeO2 catalyst; S2.3.2, mix and grind the Ru / CeO2 catalyst and nano SiC in a mass ratio of 3:1 under pressure; S2.3.3, tablet the ground sample under a pressure of 15Mpa.

2. The process for hydrogen production by electrically assisted low-temperature ammonia decomposition according to claim 1, characterized in that: In step S2.2, the stirring time is 2h.

3. The process for hydrogen production by electrically assisted low temperature ammonia decomposition according to claim 1, characterized in that: In step S2.3, the heating efficiency is 5℃ / min.

4. The process of claim 1, wherein the process is an electrically assisted low-temperature ammonia decomposition process for hydrogen production. In step S2.3, the doping amount of Ce is represented by the ratio of Ce to Zr, and the ratio of Ce to Zr is set to 0.25:0.75, and the proportion of active components Ni, Co and Fe is 10wt%.

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