A high-entropy alloy catalyst, a preparation method thereof and application thereof in a carbon dioxide and methane reforming reaction

Abstract

The application provides a high-entropy alloy catalyst, a preparation method thereof and application thereof in a carbon dioxide and methane reforming reaction, and relates to the technical field of catalysts. The high-entropy alloy catalyst provided by the application comprises a carrier and an active component loaded on the carrier; the carrier has a chemical formula shown in formula (I): AD2O4 (I); wherein the A is any one or more of Mg, Zn, Ni, Co, Ca and Cu; the D is any one or more of Al, Mn, Cr, Bi, Co, Fe and Ga; the A is not the same as the D; and the active component is a high-entropy alloy nanoparticle, and the high-entropy alloy comprises Pt, Rh, Ru, Co and Ni. The catalyst provided by the application forms a high-entropy alloy through alloying between Pt, Rh, Ru, Co and Ni, and has high catalytic activity and long-term stability in a methane dry reforming reaction.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a high-entropy alloy catalyst, its preparation method, and its application in the reforming reaction of carbon dioxide and methane. Background Technology

[0002] Against the backdrop of accelerating global industrialization, human dependence on fossil fuels continues to increase, creating an urgent need for the direct and high-value utilization of various hydrocarbon resources, especially unconventional natural gas rich in carbon dioxide (such as natural gas extracted from offshore oil and gas fields, with CO2 content reaching 20% ​​to 80%). Traditional processing methods require gas separation of this type of "carbon-rich natural gas," which is expensive and energy-intensive. Therefore, how to achieve efficient resource utilization of methane and carbon dioxide has become a global focus.

[0003] The dry reforming reaction of methane with carbon dioxide at high temperatures (>700℃) is a highly efficient and economical method for converting carbon-rich natural gas. This reaction can convert methane and carbon dioxide into a syngas mixture with a molar ratio of approximately 1:1 of hydrogen (H2) and carbon monoxide (CO). This syngas ratio is ideal for subsequent Fischer-Tropsch synthesis to produce high-value-added chemicals such as long-chain olefins.

[0004] The industrialization of methane dry reforming faces two major challenges: catalyst sintering and carbon deposition. At reaction temperatures typically above 700°C, the metal nanoparticles of catalysts (especially nickel-based ones) migrate and aggregate, leading to a reduction in active sites and an irreversible increase in particle size. Furthermore, the deep cracking of methane (CH4) and the disproportionation of carbon monoxide (CO) result in carbon species covering the active sites of the catalyst, causing rapid deactivation. Therefore, developing a methane dry reforming catalyst that combines high activity and high stability remains a significant challenge in the current research field. Summary of the Invention

[0005] In view of this, this application provides a high-entropy alloy catalyst, its preparation method, and its application in the reforming reaction of carbon dioxide and methane. The high-entropy alloy catalyst provided in this application exhibits both high catalytic activity and long-term stability when used in the dry reforming reaction of methane.

[0006] This application provides a high-entropy alloy catalyst, comprising a support and an active component supported on the support; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same. The active component is high-entropy alloy nanoparticles, and the high-entropy alloy includes Pt, Rh, Ru, Co and Ni.

[0007] In some specific implementations, the carrier is MgAl2O4.

[0008] In some specific implementations, the mass fractions of Pt, Rh, Ru, Co, and Ni are each independently 0.1% to 0.5%, and the mass fractions of Pt, Rh, Ru, Co, and Ni are the same.

[0009] In some specific implementations, the mass fractions of Pt, Rh, Ru, Co, and Ni are each independently 0.15% to 0.25%.

[0010] This application also provides a method for preparing the high-entropy alloy catalyst described in any of the above technical solutions, comprising the following steps: a) The support, Pt source, Rh source, Ru source, Co source and Ni source are mixed and reacted to obtain the catalyst precursor; b) The catalyst precursor is subjected to Joule heating reduction to obtain a high-entropy alloy catalyst; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same.

[0011] In some specific implementations, the Pt source is selected from one or more of [Pt(NH3)4](NO3)2, Pt(NH3)2(NO2)2 and [Pt(NH3)4]Cl2; The Rh source is selected from one or more of RhCl3, Rh(NO3)3 and Rh2(SO4)3; The Ru source is selected from one or both of [Ru(NH3)6]Cl3 and Ru(NO)(NO3)3; The Co source is selected from one or more of Co(NO3)2, CoCl2, and CoSO4; The Ni source is selected from one or more of Ni(NO3)2, NiCl2 and NiSO4.

[0012] In some specific implementations, the reducing gas used for Joule heating and reduction is H2, and the gauge pressure of the reducing gas is 0.05 MPa to 0.5 MPa; In the Joule heating reduction process, the pulse heating temperature is 800℃~1200℃, the conduction time is 50ms~350ms, and the cutoff time is 4000ms~8000ms.

[0013] This application also provides a method for dry reforming of methane, comprising the following steps: After reducing the high-entropy alloy catalyst described in any of the above technical solutions or the high-entropy alloy catalyst prepared by the preparation method described in any of the above technical solutions, the catalytic feed gas is subjected to a dry reforming reaction of methane. The raw materials are CH4 and CO2.

[0014] In some specific implementations, the reducing gas is a mixture of H2 and Ar, and the space velocity of the reducing gas is 20 L / g. cat / h~600L / g cat / h; The reduction temperature is 600℃~1000℃, and the heating rate is 5℃ / min~20℃ / min; The reduction time is 0.5h to 3h; The reduction pressure is atmospheric pressure.

[0015] In some specific implementations, the volume ratio of CH4 to CO2 in the raw material gas is (1~5):(1~3); The space velocity of the feed gas is 60 L / g. cat / h~2400L / g cat / h; The reaction temperature is 600℃~1000℃; The reaction was carried out at atmospheric pressure.

[0016] This application provides a high-entropy alloy catalyst, comprising a support and an active component loaded on the support; the support has the chemical formula shown in formula (I): AD2O4(I); wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; A and D are not the same; the active component is high-entropy alloy nanoparticles, and the high-entropy alloy includes Pt, Rh, Ru, Co, and Ni. The catalyst provided by this application forms a high-entropy alloy through alloying of Pt, Rh, Ru, Co, and Ni. In the dry reforming reaction of methane, the catalyst exhibits both high catalytic activity and long-term stability. Experimental results show that the high-entropy alloy catalyst provided by this application has high catalytic activity and long-term stability at 800℃ and 1000 L / g.cat Under the given conditions, the methane conversion rate reaches as high as 80.5%, and the catalytic activity per unit mass of catalyst reaches as high as 3993 μmol g. -1 s -1 Furthermore, after 100 hours of continuous reaction, the methane conversion rate can still be maintained at 80.5%. Attached Figure Description

[0017] Figure 1 The images shown are transmission electron microscopy (TEM) images and EDS elemental distribution diagrams of the catalyst described in Example 1 of this application. Figure 2 The catalytic performance of the catalysts described in Examples 1-2 of this application in the dry reforming reaction of methane; Figure 3 The catalytic performance of the catalysts described in Comparative Examples 1-5 of this application in the dry reforming reaction of methane; Figure 4 The stability of the catalyst described in Example 1 of this application in the dry reforming reaction of methane for 100 h. Detailed Implementation

[0018] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0019] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0020] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0021] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0022] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0023] This application provides a high-entropy alloy catalyst, comprising a support and an active component supported on the support; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same. The active component is high-entropy alloy nanoparticles, and the high-entropy alloy includes Pt, Rh, Ru, Co and Ni.

[0024] The catalyst provided in this application includes a support having the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca and Cu, preferably Mg, Zn or Ni, and more preferably Mg; The D is any one or more of Al, Mn, Cr, Bi, Co, Fe and Ga, preferably Al, Cr or Ga, and more preferably Al; A is not the same as D.

[0025] In some specific implementations, the carrier is preferably NiAl2O4, MgCr2O4, ZnAl2O4 or MgAl2O4, and more preferably MgAl2O4.

[0026] The catalyst provided in this application comprises an active component supported on the support, wherein the active component is a high-entropy alloy nanoparticle, and the high-entropy alloy includes Pt, Rh, Ru, Co, and Ni. In some specific implementations, the mass fractions of Pt, Rh, Ru, Co, and Ni are each independently 0.1% to 0.5%, preferably 0.15% to 0.25%, more preferably 0.18% to 0.22%, and the mass fractions of Pt, Rh, Ru, Co, and Ni are the same.

[0027] The high-entropy alloy catalyst provided in this application comprises a support and high-entropy alloy nanoparticles supported on the support. The high-entropy alloy includes Pt, Rh, Ru, Co, and Ni. This application forms a high-entropy alloy through alloying of Pt, Rh, Ru, Co, and Ni. In the dry reforming reaction of methane, the catalyst exhibits both high catalytic activity and long-term stability.

[0028] This application also provides a method for preparing the high-entropy alloy catalyst described in the above technical solution, comprising the following steps: a) The support, Pt source, Rh source, Ru source, Co source and Ni source are mixed and reacted to obtain the catalyst precursor; b) The catalyst precursor is subjected to Joule heating reduction to obtain a high-entropy alloy catalyst; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same.

[0029] This application first mixes a support, a Pt source, an Rh source, a Ru source, a Co source, and a Ni source, and then reacts them to obtain a catalyst precursor. Specifically, the support is first mixed with dilute ammonia to obtain a first solution; then the Pt source, Rh source, Ru source, Co source, and Ni source are mixed with dilute ammonia to obtain a second solution; finally, the first solution and the second solution are reacted to obtain the catalyst precursor.

[0030] The specific types of carriers described in this application are as described above and will not be repeated here. This application does not impose any special restrictions on the source of the carriers; they can be purchased commercially. This application does not impose any special restrictions on the ratio of the carrier, Pt source, Rh source, Ru source, Co source, and Ni source, as long as the loading range of each active component on the carrier is met. The specific loading amounts are as described above and will not be restricted here.

[0031] In some specific implementations, the dilute ammonia solution is a mixture of concentrated ammonia solution and water, wherein the volume ratio of concentrated ammonia solution to water is 1:3~5, preferably 1:3.5~4.5. In some specific implementations, the mass ratio of water to carrier in the dilute ammonia solution is 1:0.005~0.040, preferably 1:0.005~0.015. In some specific implementations, the mixing is preferably carried out by stirring, simply to disperse the first and second solutions evenly. In some specific implementations, the Pt source is selected from one or more of [Pt(NH3)4](NO3)2, Pt(NH3)2(NO2)2, and [Pt(NH3)4]Cl2, preferably [Pt(NH3)4](NO3)2. In some specific implementations, the Rh source is selected from one or more of RhCl3, Rh(NO3)3, and Rh2(SO4)3, preferably RhCl3. In some specific implementations, the Ru source is selected from one or both of [Ru(NH3)6]Cl3 and Ru(NO)(NO3)3, preferably [Ru(NH3)6]Cl3. In some specific implementations, the Co source is selected from one or more of Co(NO3)2, CoCl2, and CoSO4, preferably Co(NO3)2. In some specific implementations, the Ni source is selected from one or more of Ni(NO3)2, NiCl2, and NiSO4, preferably Ni(NO3)2. In some specific implementations, preferably, under stirring conditions, the second solution is slowly added dropwise to the first solution for the reaction, the dropwise rate being 0.5 mL / min to 2 mL / min, preferably 0.5 mL / min to 1.5 mL / min. In some specific implementations, the reaction temperature is 15℃ to 45℃, preferably 25℃ to 35℃; the reaction time is 20 min to 180 min, preferably 40 min to 90 min. In some specific implementations, after the reaction is completed, rotary evaporation is preferably used for separation, and the temperature of the rotary evaporation is 35℃~65℃, preferably 45℃~55℃.

[0032] After obtaining the catalyst precursor, the catalyst precursor is subjected to Joule heating reduction to obtain a high-entropy alloy catalyst. Specifically, after obtaining the catalyst precursor, the catalyst precursor is evenly spread on carbon paper, placed in a Joule heating chamber, and pulsed heating is performed by introducing reducing gas to obtain a high-entropy alloy catalyst.

[0033] In some specific implementations, the reducing gas is H2, and the gauge pressure of the reducing gas is 0.05 MPa to 0.5 MPa, preferably 0.05 MPa to 0.15 MPa. In some specific implementations, the pulse heating temperature is 800℃ to 1200℃, preferably 950℃ to 1050℃; the conduction time is 50ms to 350ms, preferably 180ms to 220ms; and the cutoff time is 4000ms to 8000ms, preferably 5000ms to 7000ms. In some specific implementations, the pulse heating is preferably performed 4 to 6 times.

[0034] This application employs electrostatic adsorption and Joule heating reduction to obtain a nano-high-entropy alloy catalyst. The catalyst carrier forms high-entropy alloy nanoparticles with uniform elemental distribution and size, exhibiting a high degree of alloying.

[0035] This application also provides a method for dry reforming of methane, comprising the following steps: After reducing the high-entropy alloy catalyst described in any of the above technical solutions or the high-entropy alloy catalyst prepared by the preparation method described in any of the above technical solutions, the catalytic feed gas is subjected to a dry reforming reaction of methane. The raw materials are CH4 and CO2.

[0036] This application preferably uses a fixed-bed reactor to carry out the above-mentioned reaction, and the catalyst described in any of the above technical solutions is loaded into the fixed-bed reactor for reaction. When the catalyst described in the above-mentioned technical solutions of this application is applied to the dry reforming reaction of methane, the catalyst needs to be pre-reduced.

[0037] In some specific implementations, a mixture of H2 and Ar is used to reduce the catalyst, with a volume ratio of H2 to Ar of 1:9. In some specific implementations, the space velocity of the reducing gas is 20 L / g. cat / h~600L / g cat / h, preferably 60L / g cat / h~360L / g cat / h. In some specific implementations, the reduction temperature is 600℃~1000℃, preferably 700℃~900℃; the heating rate is 5℃ / min~20℃ / min, preferably 5℃ / min~15℃ / min. In some specific implementations, the reduction time is 0.5h~3h, preferably 0.5h~1.5h. In some specific implementations, the reduction pressure is atmospheric pressure.

[0038] After reduction, the reduced catalyst is used to catalyze the feed gas for dry reforming of methane.

[0039] In some specific implementations, the volume ratio of CH4:CO2 in the feed gas is (1~5):(1~3), preferably (1~3):1, and more preferably 1:1. In some specific implementations, the methane dry reforming reaction further includes N2 as an internal standard gas, and the volume ratio of CH4:CO2:N2 is (1~5):(1~3):(0.1~1), preferably (1~3):1:0.5, and more preferably 1:1:0.5. In some specific implementations, the space velocity of the feed gas is 60 L / g. cat / h~2400L / g cat / h, preferably 500L / g cat / h~2000L / g cat / h, more preferably 800L / g cat / h~1200L / g cat / h. In some specific implementations, the reaction pressure is atmospheric pressure; the reaction temperature is 600℃~1000℃, preferably 700℃~900℃.

[0040] This application provides a high-entropy alloy catalyst, comprising a support and an active component loaded on the support; the support has the chemical formula shown in formula (I): AD2O4(I); wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; A and D are not the same; the active component is high-entropy alloy nanoparticles, and the high-entropy alloy includes Pt, Rh, Ru, Co, and Ni. The catalyst provided by this application forms a high-entropy alloy through alloying Pt, Rh, Ru, Co, and Ni, and in the dry reforming reaction of methane, the catalyst exhibits both high catalytic activity and long-term stability. Experimental results show that the high-entropy alloy catalyst provided by this application exhibits high catalytic activity and long-term stability at 800℃ and 1000 L / g. cat Under the given conditions, the methane conversion rate reaches as high as 80.5%, and the catalytic activity per unit mass of catalyst reaches as high as 3993 μmol g. -1 s -1 Furthermore, after 100 hours of continuous reaction, the methane conversion rate can still be maintained at 80.5%.

[0041] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0042] Example 1

[0043] Step 1: Weigh 200mg MgAl2O4, add it to 20 mL of deionized water, and add 5 mL of concentrated ammonia. Stir to disperse.

[0044] Step 2: Sequentially transfer 80 μL of 5 mg Pt / mL [Pt(NH3)4](NO3)2 aqueous solution, 103.9 μL of 3.85 mg Rh / mL RhCl3 aqueous solution, 106.7 μL of 3.75 mg Ru / mL [Ru(NH3)6]Cl3 aqueous solution, 40 μL of 10 mg Co / mL Co(NO3)2 aqueous solution, and 40 μL of 10 mg Ni / mL Ni(NO3)2 aqueous solution, and add them to 5 mL of concentrated ammonia water. Mix well and then dilute with deionized water to 25 mL.

[0045] Step 3: Slowly add the dilute ammonia solution of the above metal salt to the ammonia solution containing MgAl2O4 at a rate of 1 mL / min. After stirring at room temperature for 30 min, rotary evaporate the above solution at 50 °C and collect the catalyst precursor.

[0046] Step 4: Take the above catalyst precursor and perform Joule heating reduction. Spread the catalyst precursor evenly on carbon paper, place it in a Joule heating chamber, and introduce pure H2 with a gauge pressure of 0.1 MPa. Perform 5 pulse heating cycles, with each pulse heating temperature of 1000℃, a conduction time of 200 ms, and a cutoff time of 6000 ms, to obtain the nano high-entropy alloy PtRhRuCoNi / MgAl2O4-1 catalyst.

[0047] The catalyst was analyzed by transmission electron microscopy and EDS, and the results are shown in [reference needed]. Figure 1 , Figure 1 The images shown are transmission electron microscopy (TEM) images and EDS elemental distribution maps of the catalyst described in Example 1 of this application. Figure 1 a is a transmission electron microscope image of the catalyst described in Example 1 of this application. Figure 1 b is the EDS distribution diagram of Pt in the catalyst described in Example 1 of this application. Figure 1 c is the EDS distribution diagram of Rh in the catalyst described in Example 1 of this application. Figure 1 d is the EDS distribution diagram of Ru in the catalyst described in Example 1 of this application. Figure 1 e is the EDS distribution diagram of Co in the catalyst described in Example 1 of this application. Figure 1 f is the EDS distribution diagram of Ni in the catalyst described in Example 1 of this application. Figure 1 It can be seen that high-entropy alloy nanoparticles with uniform element distribution and size are formed on the MgAl2O4 support, and the degree of alloying is high.

[0048] Example 2

[0049] The only difference between this embodiment and Example 1 is the loading of Pt, Rh, Ru, Co, and Ni in step 2, resulting in a nano-high entropy alloy PtRhRuCoNi / MgAl2O4-2 catalyst.

[0050] Step 2: Sequentially transfer 40 μL of 5 mg Pt / mL [Pt(NH3)4](NO3)2 aqueous solution, 52 μL of 3.85 mg Rh / mL RhCl3 aqueous solution, 53.4 μL of 3.75 mg Ru / mL [Ru(NH3)6]Cl3 aqueous solution, 20 μL of 10 mg Co / mL Co(NO3)2 aqueous solution, and 20 μL of 10 mg Ni / mL Ni(NO3)2 aqueous solution, and add them to 5 mL of concentrated ammonia water. Mix well and then dilute with deionized water to 25 mL.

[0051] Comparative Example 1

[0052] The only difference between this comparative example and Example 1 is that only Pt is loaded in step 2, but the total metal loading is the same, resulting in a Pt / MgAl2O4 catalyst.

[0053] Step 2: Transfer 400 μL of 5 mg Pt / mL [Pt(NH3)4](NO3)2 aqueous solution to 5 mL of concentrated ammonia water, mix well, and then dilute with deionized water to 25 mL.

[0054] Comparative Example 2

[0055] The only difference between this comparative example and Example 1 is that only Rh is loaded in step 2, but the total metal loading is the same, resulting in an Rh / MgAl2O4 catalyst.

[0056] Step 2: Transfer 519.5 μL of 3.85 mg Rh / mL RhCl3 aqueous solution to 5 mL of concentrated ammonia water, mix well, and then dilute with deionized water to 25 mL.

[0057] Comparative Example 3

[0058] The only difference between this comparative example and Example 1 is that only Ru is loaded in step 2, but the total metal loading is the same, resulting in a Ru / MgAl2O4 catalyst.

[0059] Step 2: Transfer 533.3 μL of 3.75 mg Ru / mL [Ru(NH3)6]Cl3 aqueous solution to 5 mL of concentrated ammonia water, mix well, and then dilute with deionized water to 25 mL.

[0060] Comparative Example 4

[0061] The only difference between this comparative example and Example 1 is that only Co is loaded in step 2, but the total metal loading is the same, resulting in a Co / MgAl2O4 catalyst.

[0062] Step 2: Transfer 200 μL of 10 mg Co / mL Co(NO3)2 aqueous solution to 5 mL of concentrated ammonia water, mix well, and then dilute with deionized water to 25 mL.

[0063] Comparative Example 5

[0064] The only difference between this comparative example and Example 1 is that only Ni is loaded in step 2, but the total metal loading is the same, resulting in a Ni / MgAl2O4 catalyst.

[0065] Step 2: Transfer 200 μL of 10 mg Ni / mL Ni(NO3)2 aqueous solution to 5 mL of concentrated ammonia water, mix well, and then dilute with deionized water to 25 mL.

[0066] Experimental Example 1

[0067] The performance of the catalysts prepared in the above embodiments and comparative examples was evaluated using the following test methods: 10 mg of catalyst was placed in a fixed-bed reactor and heated to 800 °C at 10 °C / min in 10% H2 / 90% Ar at 40 sccm. Reduction was then carried out at atmospheric pressure for 1 h. The reaction temperature was maintained at 800 °C, and a certain flow rate of CH4 / CO2 / N2 (volume fraction 2 / 2 / 1) was introduced to carry out a continuous reaction at atmospheric pressure. The gas flow rate was 166.7 sccm, corresponding to a space velocity of 1000 L / g. cat / h. N2 was used as an internal standard to calculate the conversion rates of CH4 and CO2. The products were analyzed online at atmospheric pressure after passing through a cold trap. The product analysis was performed by a gas chromatograph equipped with a thermal conductivity detector (TCD) under the following chromatographic conditions: 5A molecular sieve packed column and capillary packed column (50m).

[0068] For the evaluation of the catalytic performance of the catalysts described in the above embodiments and comparative examples, please refer to [link to relevant documentation]. Figures 2-3 , Figure 2 This demonstrates the catalytic performance of the catalysts described in Examples 1-2 of this application in the dry reforming reaction of methane. Figure 3 The catalytic performance of the catalysts described in Comparative Examples 1 to 5 of this application in the dry reforming reaction of methane is shown in Table 1.

[0069] Depend on Figures 2-3 It can be seen that, under the same total metal loading conditions, the PtRhRuCoNi / MgAl2O4-1 provided in Example 1 of this application exhibits higher activity and higher stability. In the first 5 hours of reaction, the methane conversion rate of Example 1 gradually increased from 42.0% to 77.6%. In the subsequent 35 hours of reaction, its methane conversion rate slowly increased and remained at around 80.5% without decreasing further. Its methane conversion rate was calculated to be 3993 μmol g. cat -1 s -1It exhibits extremely high catalytic activity. When the loading is reduced from 1% to 0.5%, the conversion rate of the high-entropy alloy PtRhRuCoNi / MgAl2O4-2 catalyst described in Example 2 remains relatively stable at around 45%, and its methane conversion rate is calculated to be 2232 μmol g. cat -1 s -1 .

[0070] Compared to Example 1, among the single-metal catalysts, the methane conversion rate of Pt / MgAl2O4 continuously decreased to 13.0% within 20 h; the methane conversion rate of Rh / MgAl2O4 increased from 49.2% to 68.1% within 20 h, and then slowly decreased to 45.1%; the methane conversion rate of Ru / MgAl2O4 increased from 5.2% to 36.8% within 20 h; the performance of Co / MgAl2O4 was extremely low, with a maximum methane conversion rate of 3.0% within 20 h; and the methane conversion rate of Ni / MgAl2O4 increased from 11.1% to 35.0% within 20 h.

[0071] Therefore, under the same total metal loading conditions, the high-entropy alloy catalyst described in this application has better catalytic activity and long-term stability than a single metal catalyst.

[0072] Furthermore, the results of the 100-hour methane dry reforming stability evaluation of the catalyst described in Example 1 are available here. Figure 4 , Figure 4 The results are from the 100-hour dry reforming stability test of the catalyst described in Example 1 of this application. Figure 4 It can be seen that at 1000L / g cat At a space velocity of / h, the methane conversion of PtRhRuCoNi / MgAl2O4 reached approximately 80% within 20h and remained stable during the subsequent 80h test, indicating its high stability.

[0073] Therefore, by alloying Pt, Rh, Ru, Co and Ni to form a high-entropy alloy catalyst, the activity and stability of the catalyst for methane dry reforming are improved, and a catalyst with both high activity and high stability can be obtained.

[0074] Table 1. Catalytic performance evaluation of each example and comparative example.

[0075] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A high-entropy alloy catalyst, characterized in that, Includes a carrier and an active component loaded on the carrier; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same. The active component is high-entropy alloy nanoparticles, and the high-entropy alloy includes Pt, Rh, Ru, Co and Ni.

2. The high-entropy alloy catalyst according to claim 1, characterized in that, The support is MgAl2O4.

3. The high-entropy alloy catalyst according to claim 1, characterized in that, The mass fractions of Pt, Rh, Ru, Co and Ni are each independently 0.1% to 0.5%, and the mass fractions of Pt, Rh, Ru, Co and Ni are the same.

4. The high-entropy alloy catalyst according to claim 3, characterized in that, The mass fractions of Pt, Rh, Ru, Co, and Ni are each independently 0.15% to 0.25%.

5. A method for preparing the high-entropy alloy catalyst according to any one of claims 1 to 4, characterized in that, Includes the following steps: a) The support, Pt source, Rh source, Ru source, Co source and Ni source are mixed and reacted to obtain the catalyst precursor; b) The catalyst precursor is subjected to Joule heating reduction to obtain a high-entropy alloy catalyst; The carrier has the chemical formula shown in formula (I): AD2O4(I); Wherein, A is any one or more of Mg, Zn, Ni, Co, Ca, and Cu; D is any one or more of Al, Mn, Cr, Bi, Co, Fe, and Ga; and A and D are not the same.

6. The preparation method according to claim 5, characterized in that, The Pt source is selected from one or more of [Pt(NH3)4](NO3)2, Pt(NH3)2(NO2)2 and [Pt(NH3)4]Cl2; The Rh source is selected from one or more of RhCl3, Rh(NO3)3 and Rh2(SO4)3; The Ru source is selected from one or both of [Ru(NH3)6]Cl3 and Ru(NO)(NO3)3; The Co source is selected from one or more of Co(NO3)2, CoCl2, and CoSO4; The Ni source is selected from one or more of Ni(NO3)2, NiCl2 and NiSO4.

7. The preparation method according to claim 5, characterized in that, The reducing gas used in the Joule heating reduction is H2, and the gauge pressure of the reducing gas is 0.05 MPa to 0.5 MPa. In the Joule heating reduction process, the pulse heating temperature is 800℃~1200℃, the conduction time is 50ms~350ms, and the cutoff time is 4000ms~8000ms.

8. A method for dry reforming methane, characterized in that, Includes the following steps: After reducing the high-entropy alloy catalyst according to any one of claims 1 to 4 or the high-entropy alloy catalyst prepared by the preparation method according to any one of claims 5 to 7, the catalytic feed gas is subjected to a dry reforming reaction of methane. The raw materials are CH4 and CO2.

9. The method according to claim 8, characterized in that, The reducing gas used in the reduction is a mixture of H2 and Ar, and the space velocity of the reducing gas is 20 L / g. cat / h~600L / g cat / h; The reduction temperature is 600℃~1000℃, and the heating rate is 5℃ / min~20℃ / min; The reduction time is 0.5h to 3h; The reduction pressure is atmospheric pressure.

10. The method according to claim 8, characterized in that, The volume ratio of CH4 to CO2 in the raw gas is (1~5):(1~3); The space velocity of the feed gas is 60 L / g. cat / h~2400L / g cat / h; The reaction temperature is 600℃~1000℃; The reaction was carried out at atmospheric pressure.

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