A passivation method for Raney nickel and its Raney nickel catalyst and application

Abstract

The present invention provides a Raney nickel and a passivation treatment method and application thereof. The passivation treatment method comprises: transferring the sealed Raney nickel to a drying oven equipped with an air pump for drying treatment, and controlling the air flow rate in the drying oven to 100 mL / min to 5000 mL / min to purge the Raney nickel during the drying treatment; and continuously drying until the Raney nickel is converted into powder to obtain a passivated Raney nickel catalyst. The membrane electrode prepared from the Raney nickel obtained by the passivation treatment of the present invention has high activity in the electrohydrolysis reaction. The passivation treatment method of the present invention increases the specific surface area of ​​the Raney nickel catalyst by controlling the drying temperature in the passivation treatment and the air flow rate in the purge process, thereby overcoming the problems of spontaneous combustion of traditional Raney nickel when it comes into contact with air during transportation and production.

Description

Technical Field

[0001] The invention belongs to the field of electrochemistry, and particularly relates to a Raney nickel passivation method and a Raney nickel catalyst and application thereof. Background Art

[0002] Currently, developing non-precious metal catalysts that meet the activity-stability balance at industrial-grade high current densities remains a challenge for alkaline water electrolysis. However, Raney nickel (porous nickel nanoparticles) is currently an excellent catalyst for alkaline water electrolysis due to its low price, large specific surface area, high activity, and good stability.

[0003] However, traditional Raney nickel is prone to spontaneous combustion when in contact with air and must be sealed with water. Therefore, in actual use, Raney nickel must first be passivated before it can be safely used in air. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a Raney nickel passivation method and a Raney nickel catalyst and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a passivation method for Raney nickel, the passivation treatment method comprising:

[0007] The sealed Raney nickel is transferred to a drying oven equipped with an air pump for drying, and the air flow rate in the drying oven is controlled to be 100 mL / min to 5000 mL / min to purge the Raney nickel during the drying process; the drying process is continued until the Raney nickel is converted into powder to obtain a passivated Raney nickel catalyst.

[0008] In some specific embodiments of the passivation treatment method of the present invention, the sealed Raney nickel is taken out to maintain a water content of more than 10%, placed in a crucible or an evaporating dish, and transferred to a drying oven equipped with an air pump for drying.

[0009] In some specific embodiments of the passivation treatment method of the present invention, the flow rate of air in the drying oven is controlled to be 200 mL / min to 4000 mL / min to purge the Raney nickel to remove moisture in the Raney nickel. More specifically, the purge flow rate can be 500 mL / min, 1000 mL / min, 1500 mL / min, 2000 mL / min, 2500 mL / min, 3000 mL / min, or 3500 mL / min.

[0010] In some specific embodiments, the drying process is performed at a temperature of 5 to 25°C, for example, 10°C, 15°C, or 20°C.

[0011] In the specific process of the passivation treatment of the present invention, the Raney nickel is taken out of the drying oven every 6 to 12 hours, stirred to ensure that it is fully dried, and then placed in the drying oven for further drying; in some preferred embodiments, the drying treatment is continued until the mass difference of the Raney nickel before and after the drying treatment is less than 1%, and then the drying treatment can be stopped.

[0012] In some preferred embodiments, when the water content of the Raney nickel is below 35%, the drying temperature is controlled below 25° C. In some specific embodiments, when the water content of the Raney nickel to be passivated is between 25% and 35%, the temperature is directly controlled below 25° C. during the drying process, for example, 20° C., 15° C.; if the water content of the Raney nickel slowly decreases to 25% to 35% during the drying process, the drying temperature is adjusted to below 25° C., for example, 20° C., 15° C.

[0013] In some specific embodiments, the purge gas used in the purge process is selected from one or more of O2 and Ar, N2, He or CO2, for example, a mixture of air, O2 and Ar, a mixture of O2 and Ar, N2, a mixture of O2, He and CO2.

[0014] In some specific embodiments, the Raney nickel described in the present invention is a nickel-aluminum alloy with other metal elements added thereto, and the other metal elements are selected from one or more of Group IIA, Group IVA, Group IIB, Group IVB, Group VB, Group VIB, Group VIIB, Group VIII and rare earth elements, such as Mn, Mo, Ce, Cr, Co, Cu, Fe, Zn, Ti, Zr, and Pt.

[0015] In some specific embodiments, the oxygen content on the surface of the passivated Raney nickel catalyst is 3% to 22%, for example, 5%, 10%, 15%, or 20%.

[0016] In a second aspect, the present invention provides a Raney nickel catalyst, which is prepared by the above-mentioned passivation treatment method, and the specific surface area of ​​the Raney nickel catalyst is 45 to 100 m 2 / g, for example, 50m 2 / g,60m 2 / g,70m 2 / g,80m 2 / g,90m 2 / g.

[0017] In a third aspect, the present invention provides an application of an electrode prepared by the above-mentioned preparation method or prepared by the above-mentioned Raney nickel catalyst in a water electrolysis reaction.

[0018] The above technical solution has the following technical effects:

[0019] The passivation treatment method of the present invention controls the drying temperature during the passivation treatment and the air flow rate during the purge process to be controlled within a range of 100 mL / min to 5000 mL / min, so that the specific surface area of ​​the passivated coated Raney nickel catalyst obtained after the passivation treatment reaches 45 to 100 m 2 / g, which overcomes the defect that traditional Raney nickel can spontaneously combust when in contact with air and must be sealed in water before transportation and production.

[0020] The passivated film-coated Raney nickel catalyst of the present invention will not spontaneously combust or burn after coming into contact with air, does not need to be sealed with water, and is safe and reliable during transportation and use.

[0021] The membrane electrode prepared by treating the Raney nickel catalyst in the present invention has high activity in the hydrolysis reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : LSV diagram of the HER reaction of the catalyst obtained in Example 2 of the present invention;

[0023] Figure 2 : LSV diagram of the OER reaction of the catalyst obtained in Example 3 of the present invention. DETAILED DESCRIPTION

[0024] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0025] The performance testing methods of the products obtained in the following embodiments and comparative examples of the present invention are as follows:

[0026] Catalyst water content: calculated by difference method;

[0027] Surface oxygen content: calculation of hydrogen consumption of H2-TPR;

[0028] Specific surface area, pore volume: ASAP 2020Plus;

[0029] Electrochemical properties test: Princeton 4000A test conditions, 1 M KOH, Hg-HgO as the reference electrode.

[0030] Example 1

[0031] Raney nickel (containing 83% Ni, 15% Al, and 2% Mo) with a water content of 43% was removed from the water with a spatula, placed in a crucible, and transferred to a drying oven equipped with an air pump. The drying temperature in the drying oven was set to 25°C, and the flow rate of the air pump was adjusted to purge the Raney nickel at an air flow rate of 500 mL / min. After purging for 8 hours, the catalyst was removed, stirred once with a spatula, and then placed in the drying oven to continue drying. This operation was repeated several times.

[0032] After drying for 168 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measurement is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0033] Example 2

[0034] Be that 60% Raney nickel (contains 81% Ni, 11.3% Al, 7.7% Mo) takes out from water and places crucible with a spoon, and is transferred to the drying oven that is furnished with an air pump.The drying oven is set with a dry temperature of 30 ℃, and air pump simultaneously purges in the drying oven with an air flow rate of 2000mL / min, and catalyzer is taken out after the purge process 8h, and with a medicine spoon, catalyzer is stirred once, then is placed in drying oven and continues drying process, so repeated operation repeatedly.When the water content that records Raney nickel was reduced to 35%, baking temperature was reduced to 25 ℃ and proceeded to purge.

[0035] After drying for 100 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measured mass is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0036] Example 3

[0037] Be that 60% Raney nickel (containing 78% Ni, 21% Al, 7% Fe, 3% Mo) is taken out from water with a spoon and placed in a crucible, and transferred to a drying oven equipped with an air pump. The drying temperature in the drying oven is set to 30 ℃, and the air pump is purged into the drying oven at an air flow rate of 2000mL / min. After processing for 8h, the catalyst is taken out, stirred once with a medicine spoon, and then placed in a drying oven to continue drying treatment, and so repeated operation is repeated many times. When the water content of the Raney nickel is measured and is reduced to 35%, the temperature is adjusted to 20 ℃ to 25 ℃ and dried.

[0038] After drying for 12 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measurement is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0039] Example 4

[0040] Be that 60% Raney nickel (contains 81% Ni, 11.3% Al, 7.7% Mo) takes out from water and places crucible with spoon, and be transferred in the drying oven that is furnished with air pump with water content.The baking temperature in the drying oven is set to 30 ℃, and air pump simultaneously purges in the drying oven with the flow of 1500mL / min, and purge gas is 10% O2 with 90%He gas mixture.After purge treatment 8h, catalyzer is taken out, with medicine spoon, catalyzer is stirred once, then places drying oven and continues drying treatment, so repeated operation repeatedly.When the water content that records Raney nickel was reduced to 35%, baking temperature was reduced to 25 ℃ and proceeded to purge drying.

[0041] After drying for 100 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measured mass is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0042] Example 5

[0043] Be that 60% Raney nickel (contains 81% Ni, 11.3% Al, 7.7% Mo) takes out from water and places crucible with spoon, and is transferred in the drying box that is furnished with air pump with water content.The baking temperature in the drying box is set to 30 ℃, and air pump simultaneously purges in the drying box with the flow of 1200mL / min, and purge gas is 10% O 2 with 90%CO 2 gaseous mixture.After the purge process 8h, catalyzer is taken out, with medicine spoon, catalyzer is stirred once, then places drying box and continues drying process, so repetitive operation repeatedly.When the water content that records Raney nickel was reduced to 35%, baking temperature was reduced to 25 ℃ and proceeded to purge drying.

[0044] After drying for 100 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measured mass is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0045] Comparative Example 1

[0046] Raney nickel (containing 81% Ni, 8% Al, 7% Mo, and 4% Cr) with a water content of 50% was taken out of the water with a spoon and placed in a crucible. The crucible was then transferred to a drying oven equipped with an air pump. The drying temperature in the drying oven was set to 35°C, and the air pump was blown into the drying oven at an air flow rate of 6000 mL / min. After 4 hours of treatment, the catalyst was taken out, stirred once with a medicine spoon, and then placed in the drying oven to continue drying. This operation was repeated several times.

[0047] After drying for 88 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measurement is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0048] Comparative Example 2

[0049] Raney nickel (containing 85% Ni, 8% Al, 2.5% Mo, and 4.5% Co) with a water content of 50% was taken out of the water with a spoon and placed in a crucible. The crucible was then transferred to a drying oven equipped with an air pump. The drying temperature in the drying oven was set to 50°C, and the air pump was blown into the drying oven at a flow rate of 5000 mL / min. After 4 hours of treatment, the catalyst was taken out, stirred once with a spoon, and then placed in the drying oven to continue drying. This operation was repeated several times.

[0050] After drying for 72 hours, the catalyst powder is completely converted into dry powder. When the mass difference from the last measurement is less than 1%, the drying process is stopped to obtain a passivated Raney nickel catalyst.

[0051] Comparative Example 3

[0052] The water-sealed Raney nickel was filtered in a glove box to remove most of the water. The filter cake was then transferred to a crucible and dried in a fume hood. Sparks were observed several times during the drying process and were extinguished with a wash bottle. After drying for more than 24 hours, a directly passivated Raney nickel catalyst was obtained.

[0053] The passivated Raney nickel catalyst obtained above was subjected to N2 adsorption and desorption and H2-TPr detection, and the catalyst performance was measured and shown in Table 1 below:

[0054] Table 1

[0055]

[0056] The passivated Raney nickel catalyst obtained above was used as a binder with Nafion to prepare an electrode plate, which was then applied to a hydrolysis reaction. The application performance data is shown in Table 2 below:

[0057] Table 2

[0058] HER overpotential (mV) OER overpotential (mV) Example 1 370 361 Example 2 358 351 Example 3 400 321 Example 4 475 330 Example 5 363 348 Comparative Example 1 511 505 Comparative Example 2 515 520 Comparative Example 3 530 540

[0059] From the data in Table 1 above, it can be seen that the passivation treatment method of the present invention can effectively protect the catalyst from the severe oxidation process by destroying the porous structure of Raney Ni, thereby improving the catalyst activity, so that the oxygen content of the Raney nickel catalyst can be reduced to 3.28%, and the specific surface area can reach 49-73 m 2 / g, pore volume is 0.28~0.33m 2 / g.

[0060] From the attached Figure 1 、 2As can be seen from the data in Table 2, the catalyst with a high specific surface area prepared by the method of the present invention is more favorable for the OER reaction. The Raney nickel catalyst obtained by the treatment method of the present invention is applied as an electrode to the water electrolysis reaction. The overpotential of the HER reaction is 358 mV, and the overpotential of the OER reaction reaches 321 mV.

Claims

1. A passivation treatment method for Raney nickel, characterized in that, The passivation treatment method comprises: The sealed Raney nickel is transferred to a drying oven equipped with an air pump for drying, while the air flow rate in the drying oven is controlled to be 100 mL / min to 5000 mL / min to purge the Raney nickel; the drying process is continued until the Raney nickel is converted into powder to obtain a passivated Raney nickel catalyst; The sealed Raney nickel is taken out and the water content is kept above 10%, placed in a crucible or an evaporating dish, and transferred to a drying oven equipped with an air pump; the drying process is carried out at a temperature of 15 to 35°C.

2. The passivation treatment method according to claim 1, characterized in that: During the purging process, the Raney nickel is taken out every 6 to 12 hours, stirred, and then placed in a drying oven for further drying.

3. The passivation treatment method according to claim 2, characterized in that: The drying process is continued until the mass difference of the Raney nickel before and after the drying process is less than 1%, and the drying process is stopped.

4. The passivation treatment method according to claim 2, characterized in that: During the drying process, when the water content of the Raney nickel is below 35%, the drying temperature is controlled below 25°C.

5. The passivation treatment method according to any one of claims 1 to 4, characterized in that: The purge gas used in the purge process is selected from a mixture of one or more of Ar, N2, He or CO2 and O2.

6. The passivation treatment method according to any one of claims 1 to 4, characterized in that: The Raney nickel is a nickel-aluminum alloy with other metal elements added thereto, wherein the other metal elements are selected from one or more of group IIA, group IVA, group IIB, group IVB, group VB, group VIB, group VIIB, group VIII and rare earth elements.

7. The passivation treatment method according to any one of claims 1 to 4, characterized in that: The oxygen content on the surface of the passivated Raney nickel catalyst is 3% to 22%.

8. A Raney nickel catalyst, characterized in that The Raney nickel catalyst is prepared by the passivation treatment method according to any one of claims 1 to 7, wherein the specific surface area of ​​the Raney nickel catalyst is 45 to 100 m 2 / g.

9. Use of an electrode prepared by the passivation treatment method according to any one of claims 1 to 7 or prepared by using the Raney nickel catalyst according to claim 8 in a water electrolysis reaction.

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