Asphalt-based carbon metal composite material as well as preparation method and application thereof
By mixing deoiled bitumen and iron acetylacetone in the solid phase, a bitumen-based carbon metal composite material with high catalytic activity and low cost was prepared, solving the problems of low activity and complex preparation of non-precious metal catalysts in the ORR reaction of fuel cell cathodes, and achieving high efficiency electrocatalytic redox performance.
Patent Information
- Application Number
- CN202410577530.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-10
- Publication Date
- 2025-11-11
AI Technical Summary
Existing non-precious metal catalysts exhibit low activity, are prone to oxidation, agglomeration, and poisoning in the ORR reaction at the cathode of fuel cells. Their preparation processes are complex and costly. The high cost of carbon source materials and the complexity of their preparation processes also hinder their widespread application.
Using deoiled bitumen and iron acetylacetonate as raw materials, they are mixed under solid-phase conditions and then subjected to carbonization and acid washing to form a bitumen-based carbon metal composite material with a suitable pore structure and a high degree of graphitization. The special spatial configuration of iron acetylacetonate and its interaction with deoiled bitumen are utilized to form a special pore structure and improve the graphitization degree of carbon materials.
The prepared composite material exhibits high catalytic activity and methanol resistance in electrocatalytic redox reactions, reducing operational difficulty and process cost, and improving the electrochemical performance of the material.
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Figure CN120920006A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrocatalytic redox catalyst technology, specifically to a pitch-based carbon metal composite material, its preparation method, and its application. Background Technology
[0002] Fuel cells have garnered significant attention since their inception, but their widespread application has been hampered by the slow ORR (Orbital Reactor) reaction at the cathode. While commonly used Pt / C electrodes exhibit high activity, they are relatively expensive, and Pt reserves on the Earth's surface are low. Therefore, much research has focused on designing and synthesizing non-precious metal catalysts with better ORR catalytic activity. However, non-precious metal catalysts exhibit lower activity compared to precious metal catalysts. Furthermore, due to their susceptibility to oxidation, aggregation, poisoning, and acid / alkali instability, their lifespan in catalytic reactions is typically very short, leading to easy deactivation. These drawbacks are significant obstacles to the widespread application of non-precious metal catalysts. In addition, the carbon sources currently used for preparing non-precious metal catalysts are mostly organic N- and P-containing compounds and macrocyclic compounds, which are relatively expensive and often require two, three, or even multiple carbonization steps to enhance the graphitization of the carbon material, resulting in complex and costly processes. Therefore, developing low-cost methods for preparing carbon-metal composite materials is crucial. Summary of the Invention
[0003] The purpose of this invention is to overcome the problems of complex preparation process, high cost and insufficient ORR activity of the prepared carbon metal composite material in the prior art. It provides a pitch-based carbon metal composite material, its preparation method and application. The preparation method of the pitch-based carbon metal composite material has the characteristics of simple steps and low raw material cost, and the prepared composite material has excellent ORR catalytic activity.
[0004] To achieve the above objectives, the present invention provides a method for preparing an asphalt-based carbon metal composite material, comprising the following steps:
[0005] (1) The deoiled bitumen, iron source and optional pore-forming agent are mixed in a solid phase to obtain a precursor;
[0006] The iron source is iron acetylacetone; the softening point of the deoiled pitch is 90-110℃.
[0007] (2) The precursor is subjected to carbonization treatment;
[0008] (3) The carbonized product is acid washed.
[0009] Preferably, the density of the deoiled bitumen is 1-1.11 g / cm³. 3 The residual carbon rate is 50-60%, and the sulfur content is 2-3 wt%.
[0010] A second aspect of the present invention provides a pitch-based carbon metal composite material prepared by the above preparation method.
[0011] A third aspect of the present invention provides the application of the above-mentioned pitch-based carbon metal composite material in electrocatalytic oxygen reduction reaction.
[0012] The method for preparing the composite material provided by this invention uses deoiled pitch and ferric acetylacetonate as raw materials, which can realize the high-value utilization of heavy oil residue. The two can be mixed under solid-phase conditions, which reduces the difficulty of operation and avoids the generation of industrial waste liquid, thus helping to further reduce process costs. In addition, the inventors of this invention have found that the composite material obtained after carbonization and acid washing of the precursor formed by solid-phase mixing of ferric acetylacetonate and deoiled pitch has a more suitable pore structure and graphitization degree. This may be due to the special spatial configuration of ferric acetylacetonate, which can be retained in the precursor as much as possible during solid-phase mixing, thereby helping to form a special pore structure in the composite material during carbonization, which is conducive to the transfer of electrons inside the material and thus improves the electrochemical performance of the material. In a preferred case, the addition of a pore-forming agent and the synergistic effect of ferric acetylacetonate can help to further adjust the number and size of pores inside the material. On the other hand, while providing iron, ferric acetylacetonate can also effectively improve the graphitization degree of carbon materials due to the interaction between ferric acetylacetonate and deoiled pitch. The pitch-based carbon metal composite material prepared by this method exhibits high catalytic activity in electrocatalytic redox reactions and also has certain methanol resistance properties. Attached Figure Description
[0013] Figure 1 Here is a SEM image of the pitch-based carbon metal composite material prepared in Example 1;
[0014] Figure 2 Here is a SEM image of the pitch-based carbon metal composite material prepared in Example 2;
[0015] Figure 3 Here is a SEM image of the pitch-based carbon metal composite material prepared in Example 3;
[0016] Figure 4 Here is a SEM image of the pitch-based carbon metal composite material prepared in Example 4;
[0017] Figure 5 The LSV curve of the ORR reaction catalyzed by the pitch-based carbon metal composite material prepared in Example 1 is shown.
[0018] Figure 6 The LSV curves are for the ORR reaction catalyzed by the pitch-based carbon metal composite material prepared in Example 3. Detailed Implementation
[0019] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0020] The first aspect of this invention provides a method for preparing an asphalt-based carbon metal composite material, comprising the following steps:
[0021] (1) The deoiled bitumen, iron source and optional pore-forming agent are mixed in a solid phase to obtain a precursor;
[0022] The iron source is iron acetylacetone; the softening point of the deoiled pitch is 90-110℃.
[0023] (2) The precursor is subjected to carbonization treatment;
[0024] (3) The carbonized product is acid washed.
[0025] According to the present invention, the composite material obtained by solid-phase mixing of ferric acetylacetonate and deoiled bitumen, followed by carbonization and acid washing, exhibits a suitable pore structure and degree of graphitization, and displays unexpected catalytic activity in electrocatalytic redox reactions. This may be due, on the one hand, to the unique spatial configuration of ferric acetylacetonate, which allows it to remain largely within the precursor during solid-phase mixing, thus facilitating the formation of a unique pore structure in the composite material during carbonization. This promotes electron transfer within the material, thereby enhancing its electrochemical performance. On the other hand, while providing iron, the interaction between ferric acetylacetonate and deoiled bitumen effectively increases the degree of graphitization of the prepared carbon material.
[0026] In preferred cases, the synergistic effect of the pore-forming agent and iron acetylacetone helps to allow for more flexible adjustment of the number and size of pores inside the material.
[0027] In addition, existing technologies for preparing non-metallic carbon catalysts generally use organic compounds containing N and P, as well as some macrocyclic compounds, which are relatively expensive. Furthermore, they typically require two or three steps, or even multiple carbonization processes, to increase the graphitization degree of the carbon material, resulting in complex and costly preparation processes. In this invention, deoiled pitch and ferric acetylacetone are used as raw materials, enabling the high-value utilization of heavy oil residues. The two materials can be mixed under solid-phase conditions, reducing operational difficulty and avoiding the generation of industrial wastewater, thus further reducing process costs.
[0028] In this invention, the deoiled bitumen has the conventional definition in the art, referring to the residual oil that precipitates out due to insolvent in the solvent during the deasphalting process of vacuum residue, and can be commercially available. Preferably, the density of the deoiled bitumen is not less than 1 g / cm³. 3 Preferably 1-1.11 g / cm³ 3 The residual carbon content is 40-70 wt%, preferably 50-60 wt%, and the sulfur content is 1-5 wt%, preferably 2-3 wt%. The synergistic effect of the deoiled pitch with the above-preferred composition and iron acetylacetone is beneficial to the formation of a suitable pore structure in the composite material, which further facilitates the transfer of electrons inside the material and improves the electrochemical performance of the material.
[0029] In this invention, the method for testing residual carbon content is as follows: under a nitrogen atmosphere, the deoiled asphalt is carbonized at 800°C for 4 hours. The mass before carbonization is recorded as M0, and the mass after carbonization is recorded as M1. The residual carbon content (wt%) = M1 / M0 × 100%.
[0030] In this invention, there is no particular limitation on the solid-phase mixing method described in step (1). The deoiled bitumen, iron source, and optional pore-forming agent can be mixed in a one-step solid-phase process, or they can be mixed in steps. Preferably, the solid-phase mixing in step (1) includes: step (1-1) mixing the deoiled bitumen and iron source in a first solid-phase process; and step (1-2) mixing the product of the first solid-phase mixture with the pore-forming agent in a second solid-phase process. By adopting the above-mentioned preferred embodiment, it is beneficial to adjust the pore structure of the composite material and to make the metal sites more uniformly distributed inside the material, thereby improving the electrochemical performance of the composite material.
[0031] This invention does not impose particular limitations on the specific conditions and operating methods of the above-mentioned solid-phase mixing; conventional solid-phase mixing methods in the art can be used. For example, ball milling or grinding can be used. There are no particular limitations on the specific operating conditions for ball milling or grinding, and those skilled in the art can choose according to the actual situation.
[0032] According to some preferred embodiments of the present invention, the mass ratio of the deoiled bitumen to the iron source is (0.1-10):1, preferably (0.2-1):1, and can be, for example, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, etc., as specific but not limiting mass ratios or any range between the two. Within the above preferred ranges, it is beneficial for metal ions to accumulate inside the composite material, further improving the electrochemical activity of the composite material.
[0033] In this invention, to further adjust the number and size of pores within the material more flexibly, the method preferably further includes adding a pore-forming agent. This invention allows for a wide range of pore-forming agents; any substance conventionally used in the art that can create pores can be applied. Preferably, the pore-forming agent is KOH. Using KOH as a pore-forming agent, in synergy with iron acetylacetone, a composite material with a high degree of graphitization and abundant pores can be obtained, which is beneficial for further improving ORR catalytic activity.
[0034] According to the present invention, preferably, the mass ratio of the total mass of the deoiled bitumen and the iron source to the mass of the pore-forming agent is 1:(1-5), for example, typical but not limiting mass ratios such as 1:1, 1:2, 1:3, 1:4, 1:5, etc. Preferably, the mass ratio of the total mass of the deoiled bitumen and the iron source to the mass of the pore-forming agent is 1:(3-4). Adopting the above preferred embodiments is beneficial for further improving the ORR activity of the obtained composite material.
[0035] According to some preferred embodiments of the present invention, the carbonization process is carried out under an inert atmosphere provided by nitrogen and / or argon.
[0036] Preferably, the carbonization conditions include: a temperature of 600-900℃, more preferably 650-850℃, a time of 1-4h, more preferably 2-3h, and a heating rate of 5-10℃ / min, more preferably 6-8℃ / min.
[0037] According to the present invention, the acid washing in step (3) removes residual pore-forming agents and iron species from the surface of the composite material, thereby improving the specific surface area and pore size distribution of the material. Preferably, the acid washing includes: contacting the product obtained from the carbonization treatment with an aqueous solution of acid, followed by washing and drying.
[0038] The present invention does not particularly limit the type of acid, and can use conventional organic acids and / or inorganic acids in the art. Preferably, the acid is hydrochloric acid.
[0039] Preferably, the concentration of the aqueous solution of the acid is 1-6 mol / L.
[0040] Preferably, the contact temperature is 20-100℃ and the contact time is 1-4h.
[0041] The present invention does not particularly limit the washing and drying methods and conditions, and can be carried out using conventional methods in the art. Preferably, the washing can be performed using water. The drying temperature is 50-100℃, and the time is 6-12 hours.
[0042] A second aspect of the present invention provides a pitch-based carbon metal composite material prepared by the above preparation method.
[0043] According to the present invention, preferably, the pitch-based carbon metal composite material comprises an iron oxide and a graphitized carbon shell coating the surface of the iron oxide.
[0044] According to the present invention, preferably, the Fe content, calculated as Fe element, is 1-6 wt%, more preferably 1-4 wt%, based on the total amount of the pitch-based carbon metal composite material.
[0045] In this invention, the Fe content in the composite material is determined by XPS method.
[0046] Preferably, the specific surface area of the pitch-based carbon metal composite material is 700-2500 m². 2 / g, preferably 1200-2000m 2 / g.
[0047] Preferably, the pore size distribution of the pitch-based carbon metal composite material is in the range of 10-50 nm, and more preferably in the range of 10-30 nm.
[0048] In this invention, the specific surface area and pore size distribution are obtained by testing using the BET method.
[0049] A third aspect of the present invention provides the application of the above-mentioned pitch-based carbon metal composite material in electrocatalytic oxygen reduction reaction.
[0050] The present invention will be described in detail below through embodiments.
[0051] Unless otherwise specified, the raw materials used in the following examples and comparative examples are all commercially available.
[0052] The deoiled bitumen used in the following examples was purchased from Handan, Hebei Province, and had a softening point of 100℃ and a density of 1.082 g / cm³. 3 The residual carbon content was 53.26 wt%, and the sulfur content was 2.55 wt%.
[0053] Example 1
[0054] (1) The deoiled asphalt and iron acetylacetone were mixed at a mass ratio of 3:7, and the two were mixed evenly by grinding to obtain the deoiled asphalt / Fe composite material.
[0055] (2) The obtained deoiled bitumen / Fe composite material is mixed with pore-forming agent KOH at a mass ratio of 1:2 and then ground thoroughly with an agate mortar to make the mixture uniform, thus obtaining the deoiled bitumen / Fe / KOH composite material.
[0056] (3) The deoiled bitumen / Fe / KOH composite material was placed in a tube furnace and heated at 10℃ / min until it reached 700℃. The temperature was maintained for 2 hours. After carbonization, it was acid-washed with 1M hydrochloric acid at 60℃ for 2 hours to remove some of the metal present in the system. The mixture was then washed repeatedly with deionized water until the washing water was neutral. Finally, it was dried in an oven at 80℃ to obtain the bitumen-based carbon-metal composite material, denoted as S1. Based on the total mass of the composite material, the Fe content was 1.77wt%, and the specific surface area of the composite material, measured by the BET method, was 1883 m². 2 / g. Observed using a scanning electron microscope, such as Figure 1 As shown, the surface of the composite material has uniformly distributed small pores with a diameter ranging from 1 to 5 nm.
[0057] Example 2
[0058] Following the method of Example 1, except that the carbonization temperature was 900℃ and the carbonization time was 2 hours, an asphalt-based carbon metal composite material, denoted as S2, was obtained. The composition and structural parameters of this material are shown in Table 1. Based on the total mass of the composite material, the Fe content was 3.54 wt%, and the specific surface area of the composite material, measured by the BET method, was 1166.51 m². 2 / g. Observed using a scanning electron microscope, such as Figure 2 As shown, it can be seen that the surface is more severely etched by KOH, resulting in more and larger pores in the material, with pore sizes ranging from 1 to 15 nm.
[0059] Example 3
[0060] (1) The deoiled asphalt and iron acetylacetone were mixed at a mass ratio of 3:7, and the two were mixed evenly by grinding to obtain the deoiled asphalt / Fe composite material.
[0061] (2) The obtained deoiled bitumen / Fe composite material is mixed with pore-forming agent KOH at a mass ratio of 1:4, and then ground thoroughly with an agate mortar to make the mixture uniform, thus obtaining the deoiled bitumen / Fe / KOH composite material.
[0062] (3) The deoiled bitumen / Fe / KOH composite material was placed in a tube furnace and heated at 10℃ / min until it reached 700℃. The temperature was maintained for 2 hours. After carbonization, it was acid-washed with 1M hydrochloric acid at 60℃ for 2 hours to remove some of the metal present in the system. The mixture was then washed repeatedly with deionized water until the washing water was neutral. Finally, it was dried in an oven at 80℃ to obtain the bitumen-based carbon-metal composite material, denoted as S3. Based on the total mass of the composite material, the Fe content was 1.43 wt%, and the specific surface area of the composite material, measured by the BET method, was 1973 m². 2 / g. Observed using a scanning electron microscope, such as Figure 3 As shown, the material has abundant pores on both its surface and interior, with pore sizes ranging from 10 to 30 nm.
[0063] Example 4
[0064] The method of Example 3 is followed, except that in step (2), the mass ratio of the deoiled asphalt / Fe composite material to the pore-forming agent KOH is 1:1, resulting in an asphalt-based carbon metal composite material, denoted as S4. Based on the total mass of the composite material, the Fe content is 2.04 wt%, and the specific surface area of the composite material, tested by the BET method, is 1532 m². 2 / g, with pore size distribution in the range of 1-10nm.
[0065] Example 5
[0066] Following the method of Example 1, except that the carbonization temperature was 700℃ and the carbonization time was 4 hours, an asphalt-based carbon metal composite material, denoted as S5, was obtained. Based on the total mass of the composite material, the Fe element content was 0.51 wt%, and the specific surface area of the composite material, measured by the BET method, was 1098.46 m². 2 / g. Observed using a scanning electron microscope, such as Figure 4 As shown, the material surface is relatively rough, with a structure similar to "scales". Part of the carbon layer on the surface is peeled off, forming small sheet-like structures with pore sizes ranging from 1 to 20 nm.
[0067] Example 6
[0068] The method is the same as in Example 1, except that no pore-forming agent is added.
[0069] A pitch-based carbon-metal composite material, denoted as S6, was obtained. Its surface is very smooth and has a layered structure with carbon layers stacked together. The specific surface area of the composite material, measured by the BET method, is 33.5 m². 2 / g.
[0070] Comparative Example 1
[0071] The method is the same as in Example 1, except that ferric chloride is used instead of ferric acetylacetone, according to the same mass of Fe element.
[0072] The asphalt-based carbon metal composite material was obtained, denoted as DS1.
[0073] Comparative Example 2
[0074] Deoiled bitumen and iron acetylacetonate were mixed at a mass ratio of 3:7. KOH was added at a total mass ratio of 1:2. Toluene was added to mix the two evenly. Toluene was then removed by rotary evaporation. The carbonization conditions in Example 1 were used to obtain the deoiled bitumen / Fe composite material, denoted as DS2.
[0075] Performance Characterization
[0076] The ORR catalytic activity of the obtained carbon-coated material was tested using an electrochemical workstation, and the results are shown in Table 2. The test environment was a freshly prepared 0.1 mol / L KOH solution. The electrode slurry was prepared with 5 mg of catalyst, 10 μL of Nafion solution, and 500 μL of ethanol. During the test, the catalyst loading was 0.42 mg / cm³. 2 .
[0077] The LSV curves of the ORR reaction catalyzed by the carbon-metal composite materials prepared in Examples 1 and 3 are shown below. Figure 5 and Figure 6 As shown.
[0078] Table 1
[0079] Example number Half-wave potential (V) <![CDATA[Limiting current density (mA / cm 2 )]]> Average number of transferred electrons Example 1 0.74 4 Example 2 0.72 3.2 Example 3 0.764 5.46 2.94 Example 4 0.67 2.13 Example 5 0.69 2.61 Example 6 0.62 1.63 Comparative Example 1 0.47 1.11 Comparative Example 2 0.54 0.98
[0080] As can be seen from the results in Table 1, the pitch-based carbon metal composite material prepared by the preparation method provided in this invention has a high half-wave potential and limiting current density, and exhibits excellent ORR catalytic activity.
[0081] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing an asphalt-based carbon metal composite material, comprising the following steps: (1) The deoiled bitumen, iron source and optional pore-forming agent are mixed in a solid phase to obtain a precursor; The iron source is iron acetylacetone; the softening point of the deoiled pitch is 90-110℃. (2) The precursor is subjected to carbonization treatment; (3) The carbonized product is acid washed.
2. The preparation method according to claim 1, wherein, The density of the deoiled bitumen is not less than 1 g / cm³. 3 Preferably 1-1.11 g / cm³ 3 The residual carbon rate is 40-70 wt%, preferably 50-60 wt%, and the sulfur content is 1-5 wt%, preferably 2-3 wt%. Preferably, the softening point of the deoiled bitumen is 95-105℃.
3. The preparation method according to claim 1 or 2, wherein, The solid-phase mixing in step (1) includes: Step (1-1) involves first-phase mixing of the deoiled bitumen and the iron source; Step (1-2) involves mixing the product of the first solid phase mixture with a pore-forming agent in a second solid phase mixture; Preferably, the first solid-phase mixing and the second solid-phase mixing are each independently selected from ball milling or grinding.
4. The preparation method according to any one of claims 1-3, wherein, The mass ratio of the deoiled bitumen to the iron source is (0.1-10):1, preferably (0.2-1):
1.
5. The preparation method according to any one of claims 1-4, wherein, The pore-forming agent is KOH; Preferably, the ratio of the total mass of the deoiled bitumen and iron source to the mass of the pore-forming agent is 1:(1-5), more preferably 1:(3-4).
6. The preparation method according to any one of claims 1-5, wherein, The carbonization process is carried out under an inert atmosphere, which is provided by nitrogen and / or argon. Preferably, the carbonization treatment conditions include: a temperature of 600-900℃, more preferably 650-850℃, a time of 1-4h, more preferably 2-3h, and a heating rate of 5-10℃ / min, more preferably 8-10℃ / min.
7. The preparation method according to any one of claims 1-6, wherein, The pickling process includes: contacting the product obtained from the carbonization treatment with an aqueous solution of acid, followed by washing and drying; Preferably, the acid is hydrochloric acid; Preferably, the concentration of the aqueous solution of the acid is 1-6 mol / L, more preferably 1-2 mol / L; Preferably, the contact temperature is 20-100℃ and the contact time is 1-4h.
8. The pitch-based carbon metal composite material prepared by the preparation method according to any one of claims 1-7.
9. The pitch-based carbon metal composite material according to claim 8, wherein, Based on the total amount of the aforementioned pitch-based carbon metal composite material, and taking Fe element as the basis... . The calculated Fe content is 1-6 wt%, preferably 1-4 wt%; Preferably, the specific surface area of the pitch-based carbon metal composite material is 700-2500 m². 2 / g, with pore size distribution in the range of 10-50nm.
10. The application of the pitch-based carbon metal composite material according to claim 8 or 9 in electrocatalytic oxygen reduction reaction.