A hexagonal medium-entropy carbonate catalyst and its preparation method
By preparing hexagonal medium-entropy carbonate catalysts, the problems of low efficiency and easy deactivation of existing catalysts were solved, and efficient catalytic hydrolysis of sodium borohydride was achieved. The raw materials are abundant and stable, and the hydrogen production is significantly improved.
Patent Information
- Application Number
- CN202310335849.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-29
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2043-03-29
AI Technical Summary
Existing monometallic and bimetallic low-entropy carbonate catalysts are inefficient and easily deactivated in catalyzing the hydrolysis of sodium borohydride, and there are few reports on multi-metal catalysts that expose special crystal faces to promote efficient hydrogen production from sodium borohydride.
A hexagonal intermediate-entropy carbonate catalyst (CoαMnβNiγZnδ)CO3 was prepared by a one-step synthesis under hydrothermal conditions. The morphology and crystal plane were regulated by urea and ammonium fluoride to form a hexagonal structure of siderite crystal phase.
The high-efficiency catalytic sodium borohydride hydrogen production performance was achieved, with abundant raw material sources, low price, high thermodynamic and chemical stability, long life, and hydrogen production increased by 43.8 times.
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Figure CN117427674B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of inorganic functional materials, and in particular relates to a medium-entropy carbonate catalyst and a preparation method thereof. Background Art
[0002] With the increasing depletion of fossil energy, hydrogen energy has become a new energy source to solve the current energy crisis. There are many ways to produce hydrogen. Metal hydrides have unmatched advantages in hydrogen storage capacity over other materials. Therefore, metal hydride hydrogen production technology has developed rapidly. Sodium borohydride is a typical metal hydride. Sodium borohydride hydrolysis to produce hydrogen has the advantages of safety, convenience, moderate hydrogen release temperature, easy reaction control and high hydrogen production purity. It has now become a research hotspot in hydrogen production technology. However, the hydrolysis rate of pure sodium borohydride is slow and the hydrogen production rate is low. It is often necessary to add a suitable catalyst to improve the hydrogen release rate of sodium borohydride hydrolysis. Metal catalysts have been widely studied because of their high catalytic activity. Among them, precious metals are limited in use due to their high prices, while non-precious metals are low in price and high in reserves. In addition, in recent years, studies have found that the catalytic activity of some non-precious metal catalysts has been significantly improved. Therefore, from an economic point of view, it is very desirable to use non-precious metals to catalyze the hydrolysis of sodium borohydride to produce hydrogen.
[0003] Among various inexpensive transition metal catalysts, carbonates show high activity in catalyzing hydrogen production from sodium borohydride. However, monometallic and bimetallic low-entropy carbonate catalysts have the disadvantages of low efficiency and easy deactivation. Therefore, medium-entropy compounds with multiple catalytic active sites have received widespread attention. Compared with monometallic and bimetallic component catalysts, multimetallic medium-entropy and high-entropy catalysts have better application prospects in catalytic reactions. This is because the active metal can not only provide new active sites, but also promote the interaction of multiple metal components, thereby improving the catalytic performance of hydrogen production from sodium borohydride. In addition, the construction of catalysts with special polyhedral structures can expose high-index crystal faces in the catalyst, further exposing highly active catalytic sites. However, there is still a lack of reports on the construction of multimetallic carbonate catalysts with exposed special crystal faces to promote efficient hydrogen production from sodium borohydride. Summary of the Invention
[0004] The present invention aims to provide a hexagonal medium-entropy carbonate catalyst and a preparation method thereof.
[0005] To achieve the above-mentioned and other related purposes, the present invention provides a technical solution: a hexagonal medium entropy carbonate catalyst, the composition of the hexagonal medium entropy carbonate catalyst is (Co α Mn β Ni γ Zn δ)CO3, wherein α+β+γ+δ=1, 0.2<α, β, γ, δ<0.3; the crystal structure of the hexagonal medium-entropy carbonate catalyst is a single siderite crystal phase, the morphology is hexagonal, and the side has a network structure.
[0006] To achieve the above-mentioned and other related purposes, the present invention provides a technical solution: a method for preparing the hexagonal medium-entropy carbonate catalyst as claimed in the claims, comprising the following steps:
[0007] Step 1: Add cobalt salt, manganese salt, nickel salt and zinc salt into water to prepare a solution;
[0008] Step 2: adding urea and ammonium fluoride to the solution and stirring until dissolved;
[0009] Step 3: Transfer the reaction system obtained in step 2 to a reactor for reaction;
[0010] Step 4: The product prepared in step 3 is centrifuged and then dried, and then naturally cooled to obtain a hexagonal medium-entropy carbonate catalyst.
[0011] The preferred technical solution is: in step 1, the cobalt salt is at least one of chloride, nitrate, sulfate or acetate; the manganese salt is at least one of chloride, nitrate, sulfate or acetate; the nickel salt is at least one of chloride, nitrate, sulfate or acetate; and the zinc salt is at least one of chloride, nitrate, sulfate or acetate.
[0012] The preferred technical solution is: the molar ratio of the four elements cobalt, manganese, nickel and zinc is 1-3:1-3:1-3:1-3.
[0013] The preferred technical solution is: the molar ratio of urea to the total amount of the four metal ions is 5-20:1.
[0014] The preferred technical solution is: the molar ratio of ammonium fluoride to the total amount of the four metal ions is 1-10:1.
[0015] The preferred technical solution is: in step 2, stirring is performed at a temperature of 10-50° C. and a rotation speed of 100-1000 r / min.
[0016] The preferred technical solution is: in step 3, the reaction temperature is 100-190° C. and the reaction time is 4-48 hours.
[0017] The preferred technical solution is: the drying temperature is 30-90°C and the drying time is 6-48 hours.
[0018] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:
[0019] 1. The preparation process of the present invention is simple and has high production efficiency. The product is obtained by a one-step method without the need for complicated processes such as calcination.
[0020] 2. The catalyst raw materials disclosed in the present invention are abundant in source, low in price and non-toxic.
[0021] 3. The raw material conversion rate of the present invention can reach more than 98% based on nickel.
[0022] 4. Due to the synergistic effect of multiple metals and the exposed special crystal faces, the hexagonal medium-entropy carbonate catalyst prepared by the present invention has excellent catalytic performance in producing hydrogen from sodium borohydride.
[0023] 5. The hexagonal medium entropy carbonate material (CoaMnbNigZnd)CO3 provided by the present invention has high thermodynamic and chemical stability and a long service life as a catalyst for the hydrolysis of sodium borohydride. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a SEM photograph of the hexagonal medium-entropy carbonate catalyst prepared in Example 1 of the present invention.
[0025] Figure 2 3 is the XRD pattern of the hexagonal medium-entropy carbonate catalyst prepared in Examples 1 to 3 of the present invention.
[0026] Figure 3 This is a performance diagram of hydrogen production by catalyzing the hydrolysis of sodium borohydride by hexagonal medium-entropy carbonate prepared in an embodiment of the present invention. DETAILED DESCRIPTION
[0027] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in these embodiments.
[0028] See also Figure 1-3 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no technical substantive significance. Any modification of the structure, change in the proportional relationship or adjustment of the size. The following examples are provided for a better understanding of the present invention, but are not intended to limit the present invention. The experimental methods in the following examples are all conventional methods unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.
[0029] Unless otherwise specified, the reagents or materials described in the following examples are commercially available.
[0030] Example 1: A hexagonal medium-entropy carbonate catalyst and its preparation method
[0031] The preparation method comprises the following steps: first, 1.2 mmol each of cobalt chloride, manganese chloride, nickel chloride and zinc chloride is added to 80 ml of deionized water, stirred at 25°C and 200 r / min until completely dissolved, then 12 mmol of urea and 10 mmol of ammonium fluoride are added to the solution, and then transferred to a 100 ml reactor and reacted at 140°C for 6 hours. The prepared precipitate is centrifuged, washed three times with deionized water, washed three times with anhydrous ethanol, and then dried at 60°C for 8 hours to obtain a hexagonal medium entropy carbonate catalyst (Co 0.25 Mn 0.25 Ni 0.25 Zn 0.25 )CO3.
[0032] Example 2: A hexagonal medium-entropy carbonate catalyst and its preparation method
[0033] The preparation method comprises the following steps: first, 1.2 mmol each of cobalt chloride, manganese chloride, nickel chloride and zinc chloride is added to 80 ml of deionized water, stirred at 25°C and 200 r / min until completely dissolved, then 12 mmol of urea and 10 mmol of ammonium fluoride are added to the solution, and then transferred to a 100 ml reactor and reacted at 150°C for 6 hours. The prepared precipitate is centrifuged, washed three times with deionized water, washed three times with anhydrous ethanol, and then dried at 60°C for 8 hours to obtain a hexagonal medium entropy carbonate catalyst (Co 0.25 Mn 0.25 Ni 0.25 Zn 0.25 )CO3.
[0034] Example 3: A hexagonal medium-entropy carbonate catalyst and its preparation method
[0035] The preparation method comprises the following steps: first, 1.2 mmol each of cobalt chloride, manganese chloride, nickel chloride and zinc chloride is added to 80 ml of deionized water, stirred at 25°C and 200 r / min until completely dissolved, then 12 mmol of urea and 10 mmol of ammonium fluoride are added to the solution, and then transferred to a 100 ml reactor and reacted at 160°C for 6 hours. The prepared precipitate is centrifuged, washed three times with deionized water, washed three times with anhydrous ethanol, and then dried at 60°C for 8 hours to obtain a hexagonal medium entropy carbonate catalyst (Co 0.25 Mn 0.25 Ni 0.25 Zn 0.25 )CO3.
[0036] In Example 1, the entropic carbonate catalyst (Co 0.25 Mn 0.25 Ni0.25 Zn 0.25 )The morphology of CO3 is as follows Figure 1 As shown, it can be seen that the medium entropy carbonate has a hexagonal prism morphology, a smooth surface on the top, a mesh morphology on the side, and a particle size of about 5 μm. The XRD patterns of the medium entropy carbonate catalysts of the products of Examples 1 to 3 are as follows: Figure 2 As shown, the products all have a typical siderite phase, and the XRD diffraction peak position is consistent with the diffraction peak position of the standard card library PDF#29-0696, and there is no impurity diffraction peak, indicating that the product is a medium entropy carbonate with high purity. In Example 1, the medium entropy carbonate catalyst (Co 0.25 Mn 0.25 Ni 0.25 Zn 0.25 ) The performance of CO3 catalyzing the hydrolysis of sodium borohydride is as follows Figure 3 As shown in the figure, under the action of the catalyst, after 100 minutes of reaction, the hydrogen production can reach 684mmol / g, while without the addition of the medium entropy carbonate catalyst, the hydrogen production is only 15.6mmol / g. 0.25 Mn 0.25 Ni 0.25 Zn 0.25 )The addition of CO3 increased the hydrogen production by 43.8 times.
[0037] The present invention provides a hexagonal medium-entropy carbonate catalyst and a preparation method thereof. The preparation process is simple and the production efficiency is high. The product is obtained by a one-step method without the need for complex processes such as calcination. The catalyst raw materials are abundant in source, low in price, and non-toxic. The raw material conversion rate can reach more than 98% based on nickel. Due to the synergistic effect of multiple metals and the exposed special crystal faces, the hexagonal medium-entropy carbonate catalyst prepared by the present invention has excellent catalytic performance in producing hydrogen from sodium borohydride. The hexagonal medium-entropy carbonate material (Co α Mn β Ni γ Zn δ )CO3 has high thermodynamic and chemical stability and has a long life as a catalyst for the hydrolysis of sodium borohydride.
[0038] In this preparation method, urea acts as a precipitant. During the heating process, urea decomposes to produce ammonia and carbon dioxide, which further generate carbonate ions under hydrothermal conditions. In the supersaturated solution, carbonate ions and metal ions combine to form small crystal nuclei. Subsequently, through the Ostwald ripening process, the small crystals gradually disappear and large crystals gradually grow, eventually forming large crystals with a particle size of about 5 μm. If urea is not added, no product will appear.
[0039] Ammonium fluoride plays a role in morphology regulation during the reaction. During the reaction, fluoride ions are typical strong-field ligands that can coordinate with metal ions. During the precipitation of carbonate ions, the competition between fluoride ions and carbonate ions plays a structural guiding role, ultimately forming large hexagonal grains. If ammonium fluoride is not added, carbonate ions and metal ions will directly form precipitation, the production of crystals will be in a disordered state, and the hexagonal morphology cannot be obtained, and thus the exposed special crystal faces cannot be obtained.
[0040] The reaction process must be carried out under hydrothermal conditions. Under normal temperature and pressure conditions, urea will not decompose and no precipitant will appear. Even if ammonium fluoride is added, no product will appear in the end.
[0041] The hexagonal medium-entropy carbonate catalyst prepared by the present invention catalyzes the hydrolysis of sodium borohydride to produce hydrogen with a yield of up to 684 mmol / g, while the hydrogen yield is only 15.6 mmol / g when the medium-entropy carbonate catalyst is not added.
[0042] Example 4: A hexagonal medium-entropy carbonate catalyst and its preparation method
[0043] A method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 1, comprising the following steps:
[0044] Step 1: Add cobalt salt, manganese salt, nickel salt and zinc salt into water to prepare a solution;
[0045] Step 2: adding urea and ammonium fluoride to the solution and stirring until dissolved;
[0046] Step 3: Transfer the reaction system obtained in step 2 to a reactor for reaction;
[0047] Step 4: The product prepared in step 3 is centrifuged and then dried, and then naturally cooled to obtain a hexagonal medium-entropy carbonate catalyst.
[0048] A preferred embodiment is: in step 1, the cobalt salt is chloride; the manganese salt is nitrate; the nickel salt is chloride; and the zinc salt is sulfate.
[0049] A preferred embodiment is that the molar ratio of the four elements cobalt, manganese, nickel and zinc is 1:1:1:1.
[0050] A preferred embodiment is that the molar ratio of urea to the total amount of the four metal ions is 5:1.
[0051] A preferred embodiment is that the molar ratio of ammonium fluoride to the total amount of the four metal ions is 1:1.
[0052] A preferred embodiment is as follows: in step 2, stirring is performed at a temperature of 10° C. and a rotation speed of 100 r / min.
[0053] A preferred embodiment is: in step 3, the reaction temperature is 100° C. and the reaction time is 4 hours.
[0054] A preferred embodiment is as follows: the drying temperature is 30° C. and the drying time is 6 hours.
[0055] Example 5: A hexagonal medium-entropy carbonate catalyst and its preparation method
[0056] A method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 1, comprising the following steps:
[0057] Step 1: Add cobalt salt, manganese salt, nickel salt and zinc salt into water to prepare a solution;
[0058] Step 2: adding urea and ammonium fluoride to the solution and stirring until dissolved;
[0059] Step 3: Transfer the reaction system obtained in step 2 to a reactor for reaction;
[0060] Step 4: The product prepared in step 3 is centrifuged and then dried, and then naturally cooled to obtain a hexagonal medium-entropy carbonate catalyst.
[0061] A preferred embodiment is: in step 1, the cobalt salt is nitrate; the manganese salt is nitrate,; the nickel salt is nitrate; and the zinc salt is nitrate.
[0062] A preferred embodiment is that the molar ratio of the four elements cobalt, manganese, nickel and zinc is 2:2:2:3.
[0063] A preferred embodiment is that the molar ratio of urea to the total amount of the four metal ions is 20:1.
[0064] A preferred embodiment is that the molar ratio of ammonium fluoride to the total amount of the four metal ions is 10:1.
[0065] A preferred embodiment is as follows: in step 2, stirring is performed at a temperature of 50° C. and a rotation speed of 1000 r / min.
[0066] A preferred embodiment is: in step 3, the reaction temperature is 190° C. and the reaction time is 48 hours.
[0067] A preferred embodiment is as follows: the drying temperature is 90° C. and the drying time is 48 hours.
[0068] The above description is only used to explain the preferred embodiments of the present invention and is not intended to limit the present invention in any form. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included in the scope of protection intended by the present invention.
Claims
1. A hexagonal medium-entropy carbonate catalyst, characterized in that: The composition of the hexagonal medium entropy carbonate catalyst is (Co α Mn β Ni γ Zn δ )CO3, wherein α+β+γ+δ=1, 0.2<α, β, γ, δ<0.3; the crystal structure of the hexagonal medium-entropy carbonate catalyst is a single siderite crystal phase, the morphology is hexagonal, and the side has a network structure.
2. A method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 1, characterized in that: The following steps are involved: Step 1: Add cobalt salt, manganese salt, nickel salt and zinc salt into water to prepare a solution; Step 2: adding urea and ammonium fluoride to the solution and stirring until dissolved; Step 3: Transfer the reaction system obtained in step 2 to a reactor for reaction; Step 4: The product prepared in step 3 is centrifuged and then dried, and then naturally cooled to obtain a hexagonal medium-entropy carbonate catalyst.
3. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: In step 1, the cobalt salt is at least one of chloride, nitrate, sulfate or acetate; the manganese salt is at least one of chloride, nitrate, sulfate or acetate; the nickel salt is at least one of chloride, nitrate, sulfate or acetate; and the zinc salt is at least one of chloride, nitrate, sulfate or acetate.
4. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: The molar ratio of the four elements cobalt, manganese, nickel and zinc is 1-3:1-3:1-3:1-3.
5. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: The molar ratio of urea to the total amount of the four metal ions is 5-20:
1.
6. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: The molar ratio of ammonium fluoride to the total amount of the four metal ions is 1-10:
1.
7. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: In step 2, stirring is performed at a temperature of 10-50° C. and a rotation speed of 100-1000 r / min.
8. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: In step 3, the reaction temperature is 100-190° C. and the reaction time is 4-48 h.
9. The method for preparing the hexagonal medium-entropy carbonate catalyst according to claim 2, wherein: The drying temperature is 30-90℃ and the drying time is 6-48h.