Mofs derived oxygen uncoupling oxygen carriers, and preparation method and application thereof

Abstract

The application provides a MOFs derived oxygen uncoupling oxygen carrier, a preparation method and application thereof, and belongs to the technical field of catalysts. a O b / Fe-MgMOF, wherein A includes Cu, Co or Mn, a is 0.5-2, and b is 1-3. The application adopts a two-step catalysis method of a hydrothermal method and then an impregnation method to prepare the MOFs derived oxygen uncoupling oxygen carrier by taking Fe-MgMOFs as a carrier and metal oxides (CuO, CoO, Mn2O3) with oxygen uncoupling capacity as a loading material. The preparation method of the application enables the active components in the oxygen carrier to be highly dispersed, and improves the oxygen uncoupling performance of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a MOF-derived oxygen decoupling carrier, its preparation method, and its application. Background Technology

[0002] Hydrogen energy boasts advantages such as abundant reserves, zero pollution, high energy density, and wide applicability. However, the hydrogen production industry currently faces problems such as reliance on fossil fuel technologies and severe carbon emissions. Therefore, developing green hydrogen production technologies is a current research hotspot, with bioethanol attracting significant attention due to its unique raw material advantages. Methods for producing hydrogen through ethanol reforming include steam reforming, partial oxidative reforming, autothermal reforming, dry reforming, plasma reforming, chemical looping reforming, and aqueous phase reforming. Among these, chemical looping reforming, with its self-heating function under normal pressure, has broad application prospects due to its ease of operation, high efficiency, good durability, and environmental friendliness. However, this technology has relatively high requirements for the oxygen carrier. Developing and optimizing oxygen carriers is a crucial issue that needs to be addressed to achieve hydrogen production from bioethanol through chemical looping steam reforming.

[0003] For chemical chain reforming technology, its oxygen-carrying capacity and reactivity are difficult to meet the requirements. After multiple cycles, some oxygen carriers undergo structural changes and loss of active sites, resulting in a decrease in oxygen-carrying capacity and reactivity, which affects the efficiency and stability of the chemical chain.

[0004] Currently, metal-organic framework (MOF) derivatives, as an emerging class of materials, inherit the advantages of MOFs due to their tunable structures and multiple functions, showing great potential in various catalytic reactions. Metal-organic frameworks are a class of crystalline porous materials with a periodic network structure, formed by the self-assembly of metal ions or metal clusters and organic ligands. Their abundant metal active sites, high specific surface area, and high porosity provide ideal precursors for the preparation of high-performance oxygen carriers. However, the performance of single-metal MOFs is mainly determined by the properties of the single metal, and their active centers may not meet the needs of complex reactions.

[0005] In bimetallic MOFs, the two metals can generate synergistic effects such as electronic and lattice effects, providing more active sites, altering reaction pathways and rates, and improving catalytic efficiency. However, bimetallic MOFs are quite sensitive to temperature, humidity, and chemical environment. In some bimetallic MOFs, the organic ligands easily decompose at high temperatures, thus destroying the entire framework structure. Bimetallic MOF-derived oxides are products obtained through pyrolysis and calcination. In this process, the organic ligands are decomposed and removed, leaving only the oxide structure composed of metals. Their structure is typically nanoscale metal oxide particles, which may retain some structural features of the MOF precursor, such as a certain degree of porosity. Compared to transition metal oxides obtained by sol-gel and impregnation methods, MOF derivatives obtained by pyrolysis or calcination have a highly porous structure, thus potentially providing additional catalytic active sites on the internal pore surface, and even serving as advanced multifunctional materials for ethanol decomposition for hydrogen production. Despite the advantages of bimetallic MOF-derived oxides, their oxygen-carrying capacity and reactivity still fall short of the requirements of chemical chains. After multiple cycles, some oxygen carriers experience a decrease in oxygen-carrying capacity and reactivity due to structural changes and loss of active sites, affecting the efficiency and stability of the chemical chain.

[0006] Therefore, it is very important to provide a highly active, high oxygen-carrying capacity bimetallic MOF-derived oxygen decoupling oxygen carrier. Summary of the Invention

[0007] The purpose of this invention is to provide a MOF-derived oxygen decoupling oxygen carrier, its preparation method, and its application, in order to solve the technical problem that the oxygen carrying capacity of the oxygen carrier decreases and the reactivity decreases in the prior art, thereby affecting the efficiency and stability of the chemical chain.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a MOF-derived oxygen decoupling carrier, the general formula of which is: A a O b / Fe-Mg MOF, where A includes Cu, Co or Mn, a is 0.5 to 2, and b is 1 to 3;

[0010] The A a O b The mass ratio of Fe-Mg MOFs support to Fe-Mg MOFs support is 29–43:51–68.

[0011] This invention provides a method for preparing the MOF-derived oxygen decoupling carrier, comprising the following steps:

[0012] 1) A water-soluble Fe salt precursor, Mg salt precursor, terephthalic acid ligand and N,N-dimethylformamide solution were mixed and then subjected to a hydrothermal reaction. After centrifugation and drying, Fe-Mg MOFs support was obtained.

[0013] 2) The Fe-Mg MOFs support was dissolved in a metal salt solution with oxygen decoupling capability to obtain a mixed solution. Then, NaBH4 solution was added and mixed. After centrifugation and drying, the oxygen carrier precursor was obtained.

[0014] 3) Calcining the oxygen carrier precursor yields MOF-derived oxygen decoupled oxygen carriers.

[0015] Furthermore, the Fe salt precursor is Fe(NO3)3·9H2O, and the Mg salt precursor is Mg(NO3)2·6H2O;

[0016] The terephthalic acid ligand is C8H6O4.

[0017] Furthermore, the ratio of the Fe salt precursor, Mg salt precursor, terephthalic acid ligand, and N,N-dimethylformamide solution is 16-20 mmol: 16-20 mmol: 16-20 mmol: 180 mL.

[0018] The mass concentration of the N,N-dimethylformamide solution is ≥99%;

[0019] The ratio of Fe-Mg MOFs support, metal salt solution with oxygen decoupling capability, and NaBH4 solution is 5-15g:200mL:200mL.

[0020] The metal salt solution with oxygen decoupling capability includes Cu, Co or Mn, and the concentration of the metal salt solution with oxygen decoupling capability is 20-30 mmol / L.

[0021] The mass concentration of the NaBH4 solution is 1-2%.

[0022] Furthermore, in step 1), the mixing is carried out by stirring, the mixing temperature is 15-40°C, and the mixing time is 10-50 min;

[0023] The hydrothermal reaction temperature is 140–180°C, and the hydrothermal reaction time is 6–10 h.

[0024] Furthermore, in step 2), the mixing is carried out by stirring for 30 to 120 minutes at a temperature of 20 to 40°C.

[0025] Furthermore, in steps 1) and 2), the centrifugation speed is independently 8000-12000 r / min, and the centrifugation time is independently 3-7 min.

[0026] Furthermore, in steps 1) and 2), the drying temperature is independently 90–120°C, and the drying time is independently 10–14 h.

[0027] Furthermore, in step 3), the calcination temperature is 800–1000℃; the calcination time is 1–3 hours.

[0028] The present invention also provides an application of the MOFs-derived oxygen decoupling carrier in the oxygen decoupling steam reforming of the bioethanol chemical chain for hydrogen production.

[0029] The beneficial effects of this invention are:

[0030] 1) This invention uses Fe-Mg MOFs as a support and metal oxides (CuO, CoO, Mn2O3) with oxygen decoupling ability as loading materials. A two-step catalytic method, consisting of hydrothermal method followed by impregnation method, is used to prepare MOFs-derived oxygen decoupling carriers. The preparation method of this invention makes the active components in the oxygen carrier highly dispersed. Cu exists in the oxygen carrier as CuO, Co exists in the oxygen carrier as CoO, and Mn exists in the oxygen carrier as Mn2O3, which improves the oxygen decoupling performance of the catalyst. Moreover, the preparation method provided by this invention is relatively simple and the raw material cost is low.

[0031] 2) The MOFs-derived oxygen decoupling carrier of the present invention can be used for hydrogen production through oxygen decoupling steam reforming in the bioethanol chemical chain. Attached Figure Description

[0032] Figures 1-2 This is a transmission electron microscope image of the CuO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 1 of this invention;

[0033] Figures 3-4 This is a transmission electron microscope-elemental surface scan of the CuO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 1 of this invention.

[0034] Figure 5 The image shows the Fe element distribution in the CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 1 of this invention.

[0035] Figure 6 The Mg element distribution diagram is shown in the CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 1 of this invention.

[0036] Figure 7The image shows the Cu element distribution in the CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 1 of this invention.

[0037] Figure 8 The X-ray diffraction pattern of the CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 1 of this invention;

[0038] Figures 9-10 This is a transmission electron microscope image of the CoO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 2 of this invention;

[0039] Figures 11-12 This is a transmission electron microscopy-elemental surface scan of the CoO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 2 of this invention;

[0040] Figure 13 The image shows the Fe element distribution in the CoO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 2 of this invention.

[0041] Figure 14 The Mg element distribution diagram is shown in the CoO / Fe-Mg MOF-derived oxygen decoupling carrier prepared in Example 2 of this invention.

[0042] Figure 15 The distribution diagram of Co element in the CoO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 2 of this invention;

[0043] Figure 16 The X-ray diffraction pattern of the CoO / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 2 of this invention;

[0044] Figures 17-18 This is a transmission electron microscope image of the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 3 of the present invention;

[0045] Figures 19-20 This is a transmission electron microscope-elemental surface scan of the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled carrier prepared in Example 3 of the present invention;

[0046] Figure 21 The image shows the Fe element distribution in the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 3 of this invention.

[0047] Figure 22 The Mg element distribution diagram is shown in the Mn2O3 / Fe-Mg MOF-derived oxygen decoupling carrier prepared in Example 3 of this invention.

[0048] Figure 23The distribution diagram of Mn element in the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 3 of this invention;

[0049] Figure 24 The X-ray diffraction pattern of the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier prepared in Example 3 of this invention;

[0050] Figure 25 Volume distribution diagrams of H2, CO2, CO, and CH4 mixed gases in MOF-derived oxygen decoupled oxygen carriers prepared in Examples 1-3 at different temperatures;

[0051] Figure 26 Thermogravimetric cycle test curves of the MOF-derived oxygen decoupled oxygen carriers prepared in Examples 1-3 are shown. Detailed Implementation

[0052] This invention provides a MOF-derived oxygen decoupling carrier, the general formula of which is: A a O b / Fe-Mg MOF, wherein A includes Cu, Co or Mn, a is 0.5 to 2, preferably 0.6 to 1.8, more preferably 0.8 to 1.5; b is 1 to 3, preferably 1.2 to 2.8, more preferably 1.5 to 2.5;

[0053] The A a O b The mass ratio of the Fe-Mg MOFs support to the support is 29-43:51-68, preferably 30-41:52-66, and more preferably 32-40:55-65.

[0054] In this invention, when A a O b When the Fe-Mg MOF is CuO / Fe-Mg MOF, the preferred mass ratio of CuO to Fe-Mg MOF support is 31-32:67-68; when A a O b When the Fe-Mg MOF is CoO / Fe-Mg MOF, the preferred mass ratio of CoO to Fe-Mg MOF support is 42-43:56-57; when A a O b When the Fe-Mg MOF is Mn2O3 / Fe-Mg MOF, the preferred mass ratio of Mn2O3 to Fe-Mg MOF support is 38-39:60-61.

[0055] This invention provides a method for preparing the MOF-derived oxygen decoupling carrier, comprising the following steps:

[0056] 1) A water-soluble Fe salt precursor, Mg salt precursor, terephthalic acid ligand and N,N-dimethylformamide solution were mixed and then subjected to a hydrothermal reaction. After centrifugation and drying, Fe-Mg MOFs support was obtained.

[0057] 2) The Fe-Mg MOFs support was dissolved in a metal salt solution with oxygen decoupling capability to obtain a mixed solution. Then, NaBH4 solution was added and mixed. After centrifugation and drying, the oxygen carrier precursor was obtained.

[0058] 3) Calcining the oxygen carrier precursor yields MOF-derived oxygen decoupled oxygen carriers.

[0059] In this invention, the Fe salt precursor is preferably Fe(NO3)3·9H2O, and the Mg salt precursor is preferably Mg(NO3)2·6H2O.

[0060] The preferred terephthalic acid ligand is C8H6O.

[0061] In this invention, the ratio of Fe salt precursor, Mg salt precursor, terephthalic acid ligand and N,N-dimethylformamide solution is 16-20 mmol: 16-20 mmol: 16-20 mmol: 180 mL, preferably 17-19 mmol: 17-19 mmol: 17-19 mmol: 180 mL, and more preferably 18 mmol: 18 mmol: 18 mmol: 180 mL;

[0062] The mass concentration of the N,N-dimethylformamide solution is ≥99%, preferably ≥99.3%, and more preferably ≥99.5%.

[0063] The ratio of the Fe-Mg MOFs support, the metal salt solution with oxygen decoupling capability, and the NaBH4 solution is 5-15 g: 200 mL: 200 mL, preferably 7-12 g: 200 mL: 200 mL, and more preferably 10 g: 200 mL: 200 mL.

[0064] The metal salt solution with oxygen decoupling capability includes Cu, Co or Mn, preferably Cu or Co, and more preferably Cu;

[0065] The concentration of the metal salt solution with oxygen decoupling capability is 20–30 mmol / L, preferably 22–28 mmol / L, and more preferably 24–26 mmol / L;

[0066] The mass concentration of the NaBH4 solution is 1-2%, preferably 1.2-1.8%, and more preferably 1.4-1.6%.

[0067] In this invention, in step 1), the mixing is carried out by stirring, the mixing temperature is 15-40°C, preferably 20-35°C, and more preferably 25-30°C; the mixing time is 10-50 min, preferably 15-45 min, and more preferably 20-40 min.

[0068] The temperature of the hydrothermal reaction is 140–180°C, preferably 145–175°C, and more preferably 150–170°C; the time of the hydrothermal reaction is 6–10 h, preferably 7–9 h, and more preferably 8 h.

[0069] In this invention, in step 2), the mixing is carried out by stirring, and the stirring time is 30-120 min, preferably 35-110 min, more preferably 40-100 min; the stirring temperature is 20-40℃, preferably 25-35℃, more preferably 30℃.

[0070] In this invention, in steps 1) and 2), the centrifugation speed is independently 8000-12000 r / min, preferably 8500-11500 r / min, and more preferably 9000-11000 r / min; the centrifugation time is independently 3-7 min, preferably 4-6 min, and more preferably 5 min.

[0071] In this invention, in steps 1) and 2), the drying temperature is independently 90-120°C, preferably 95-115°C, and more preferably 100-110°C; the drying time is independently 10-14h, preferably 11-13h, and more preferably 12h.

[0072] In this invention, in step 3), the calcination temperature is 800-1000℃, preferably 850-950℃, and more preferably 900℃; the calcination time is 1-3h, preferably 1.5-2.5h, and more preferably 2h.

[0073] The present invention also provides an application of the MOFs-derived oxygen decoupling carrier in the oxygen decoupling steam reforming of the bioethanol chemical chain for hydrogen production.

[0074] In this invention, the chemical looping reforming hydrogen production technology is mainly based on the principle of chemical looping combustion, achieving hydrogen production through the alternating operation of two reactors. In the fuel reactor, a solid oxygen carrier releases lattice oxygen to react with the fuel, oxidizing the fuel into syngas. Simultaneously, the oxygen carrier is reduced to a low-valence metal oxide or metal. The reduced oxygen carrier is then transported to the air reactor for oxidation and regeneration upon contact with air. The oxygen in the air oxidizes the low-valence oxygen carrier to a high-valence state, restoring its lattice oxygen content and preparing it for the next cycle. Chemical looping oxygen decoupling steam reforming for hydrogen production allows the solid oxygen carrier to release molecular oxygen as a gasifying agent, reducing the cost of the gasification reaction. Simultaneously, the metal ions in the oxygen carrier act as a catalyst during gasification, accelerating the reaction process. Therefore, the development of the oxygen carrier is crucial for chemical looping reforming hydrogen production.

[0075] In this invention, copper oxide, cobalt oxide, and manganese oxide possess oxygen decoupling capabilities at certain temperatures. Applying these three oxides to an oxygen carrier enables chemical loop oxygen decoupling reforming for hydrogen production. The uniform pore shape and size in MOFs allow substrate molecules of specific shapes and sizes to enter, thereby achieving reaction selectivity. The pores in MOFs enable reactions to occur not only on the material surface but also at internal active sites. Therefore, loading elements with oxygen decoupling capabilities onto MOFs can achieve chemical loop steam reforming for hydrogen production from bioethanol.

[0076] In this invention, the specific steps for applying the above-mentioned MOFs-derived oxygen decoupling carrier in the oxygen decoupling steam reforming of bioethanol chemical chain to produce hydrogen include: a certain amount of oxygen carrier is placed in the bed of a fixed-bed reactor, N2 is introduced to remove air from the bed and maintain an inert atmosphere in the bed; the reaction temperature is set to 500-900°C, and a mixture of ethanol and water is introduced. The ethanol and water mixture is first vaporized in a preheater, and then mixed with N2 and introduced into the reactor to react with the oxygen carrier. After cooling, a mixture of gases such as H2, CO2, CO, and CH4 is obtained.

[0077] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0078] The Cu(NO3)2·xH2O, Fe(NO3)3·9H2O, Mg(NO3)2·6H2O, Co(NO3)2·6H2O, Mn(NO3)2·4H2O, terephthalic acid ligand C8H6O4, ethanol, deionized water, and N,N-dimethylformamide used in the embodiments of this invention are all of analytical grade.

[0079] Example 1

[0080] 18 mmol Fe(NO3)3·9H2O, 18 mmol Mg(NO3)2·6H2O, and 18 mmol terephthalic acid C8H6O4 were poured into a beaker, and 180 mL of N,N-dimethylformamide solution was added. The mixture was stirred evenly with a glass rod and placed on a magnetic stirrer. The mixture was stirred at 20 °C for 15 min to dissolve the organic ligands and prepare a Fe-Mg mixed solution. The Fe-Mg mixed solution was then poured into a polytetrafluoroethylene liner and placed in a hydrothermal reaction chamber. The hydrothermal reaction was carried out at 160 °C for 8 h. After the reaction, a solid-liquid mixture was obtained. The solid-liquid mixture was centrifuged at 10000 r / min for 5 min. After the centrifugation, the supernatant was removed, and the solid product was placed in a forced-air drying oven at 100 °C for 12 h to obtain the Fe-Mg MOFs support.

[0081] Cu(NO3)2·xH2O was prepared as a copper salt solution with a concentration of 25 mmol / L. Then, Fe-Mg MOFs support was dissolved in the copper salt solution and stirred at room temperature for 30 min to obtain a mixed solution. Next, a NaBH4 solution with a mass concentration of 1.23% was added to the mixed solution and stirred continuously for 2 h to obtain a solid-liquid mixture. The ratio of Fe-Mg MOFs support, metal salt solution with oxygen decoupling ability and NaBH4 solution was 10 g: 200 mL: 200 mL. The solid-liquid mixture was centrifuged at a speed of 10000 r / min for 5 min. After centrifugation, the supernatant was removed, and the solid product was placed in a forced-air drying oven at a temperature of 100℃ for 12 h to obtain CuO / Fe-Mg MOF oxygen carrier precursor.

[0082] The oxygen carrier precursor was heated to 1000℃ at a rate of 10℃ / min for 2 hours. After calcination, CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier was obtained.

[0083] The MOF-derived oxygen decoupled oxygen carrier prepared in Example 1 was tested, and the test results are as follows: Figures 1-8 As shown. From Figures 1-2 It can be seen that a large number of rod-shaped objects are stacked together; from Figures 3-4 It can be seen that the oxygen carrier has a rod-like structure; from Figures 5-7 It can be seen that the Fe, Mg, Cu, and O elements are uniformly distributed in the rod-shaped structure; Figure 8 It can be seen that the phases of the CuO / Fe-Mg MOF derived oxygen decoupled oxygen carrier are CuFe2O4 and MgFe2O4, respectively, with sharp diffraction peaks at 2θ = 18.32, 30.17, 35.53, 43.17, 57.09, and 62.68°, indicating high crystallinity.

[0084] Example 2

[0085] Compared with Example 1, the difference in Example 2 is that Co(NO3)2·6H2O was prepared as a cobalt salt solution with a concentration of 25 mmol / L, and the oxygen carrier precursor was calcined at a temperature of 800°C.

[0086] The preparation method is the same as in Example 1, and a CoO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is obtained.

[0087] The MOF-derived oxygen decoupling carrier prepared in Example 2 was tested, and the test results are as follows: Figures 9-16 As shown. From Figures 9-10 It can be seen that a large number of rod-shaped objects are stacked together; from Figures 11-12 It can be seen that the oxygen carrier has a rod-like structure; from Figures 13-15 It can be seen that Fe, Mg, Co, and O elements are uniformly distributed in the rod-shaped structure; from Figure 16 It can be seen that the phases of the CoO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier are CoFe2O4 and MgFe2O4, respectively, with moderate intensity diffraction peaks at 2θ = 30.06, 37.16, 43.17, 53.58, and 62.68°, indicating relatively low crystallinity.

[0088] Example 3

[0089] Compared with Example 1, the difference in Example 3 is that Mn(NO3)2·4H2O was prepared as a manganese salt solution with a concentration of 25 mmol / L, and the oxygen carrier precursor was calcined at a temperature of 900°C.

[0090] The preparation method is the same as in Example 1, and a Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is obtained.

[0091] The MOF-derived oxygen decoupling carrier prepared in Example 3 was tested, and the test results are as follows: Figures 17-24 As shown. From Figures 17-18 It can be seen that a large number of rod-shaped objects are stacked together; from Figures 19-20 It can be seen that the oxygen carrier has a rod-like structure; from Figures 21-23 It can be seen that Fe, Mg, and O elements are uniformly distributed in the rod-like structure, while the distribution of Mn element is relatively loose; from Figure 24 It can be seen that the phases of the MnO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier are (Mn 0.983 Fe 0.017 )2O3 and MgFe2O4 show sharp diffraction peaks at 2θ = 23.13, 32.93, 35.66, 49.31, 53.25, 64.04°, indicating high crystallinity.

[0092] The MOF-derived oxygen decoupling carriers prepared in Examples 1-3 were used for hydrogen production via oxygen decoupling steam reforming in the bioethanol chemical chain. The specific method included: placing 0.3 g of CuO / Fe-Mg MOF-derived oxygen decoupling carriers, CoO / Fe-Mg MOF-derived oxygen decoupling carriers, and Mn2O3 / Fe-Mg MOF-derived oxygen decoupling carriers into the bed of a fixed-bed reactor for reaction. Before the reaction, N2 was introduced to purge air from the bed and maintain an inert atmosphere. The reaction temperature was set to 500-900℃. A mixture of ethanol and water was introduced, which was first vaporized in a preheater, then mixed with N2 and introduced into the reactor to react with the oxygen carriers. After cooling, a mixed gas of H2, CO2, CO, and CH4 was obtained. The test results are as follows: Figures 25-26 As shown. From Figure 25 It can be seen that the hydrogen volume increases significantly with increasing temperature. Among the three oxygen carriers, the CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier exhibits the best hydrogen production performance at 900℃. The optimal hydrogen production temperature for the CoO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is also at 900℃, while the optimal hydrogen production temperature for the Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is at 800℃. Figure 26 It can be seen that the oxygen release temperature of CuO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is 800-1000℃, that of CoO / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is 800-1000℃, and that of Mn2O3 / Fe-Mg MOF-derived oxygen decoupled oxygen carrier is 700-1000℃. This further indicates that the prepared MOF-derived oxygen decoupled oxygen carrier can generate more hydrogen at the oxygen release temperature.

[0093] As can be seen from the above embodiments, the present invention provides a MOF-derived oxygen decoupling carrier, its preparation method, and its application. The general formula of the MOF-derived oxygen decoupling carrier is: A a O b / Fe-MgMOF, where A includes Cu, Co, or Mn, a is 0.5–2, and b is 1–3. This invention uses Fe-MgMOFs as a support and metal oxides (CuO, CoO, Mn2O3) with oxygen decoupling capability as the loading material. A two-step catalytic method, consisting of a hydrothermal method followed by an impregnation method, is employed to prepare MOFs-derived oxygen decoupling carriers. The preparation method of this invention highly disperses the active components in the oxygen carrier, thereby improving the oxygen decoupling performance of the catalyst.

[0094] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing MOFs derived oxy-decoupled oxygen carriers, characterized in that, Includes the following steps: 1) A water-soluble Fe salt precursor, Mg salt precursor, terephthalic acid ligand and N,N-dimethylformamide solution were mixed, followed by hydrothermal reaction, centrifugation and drying to obtain Fe-Mg MOFs support; 2) The Fe-Mg MOFs support was dissolved in a metal salt solution with oxygen decoupling capability to obtain a mixed solution. Then, NaBH4 solution was added and mixed. After centrifugation and drying, the oxygen carrier precursor was obtained. 3) Calcining the oxygen carrier precursor yields MOF-derived oxygen decoupled oxygen carriers; The Fe salt precursor is Fe(NO3)3·9H2O, and the Mg salt precursor is Mg(NO3)2·6H2O; The terephthalic acid ligand is C8H6O4; The ratio of Fe salt precursor, Mg salt precursor, terephthalic acid ligand and N,N-dimethylformamide solution is 16~20 mmol: 16~20 mmol: 16~20 mmol: 180 mL. The mass concentration of the N,N-dimethylformamide solution is ≥99%; The ratio of Fe-Mg MOFs support, metal salt solution with oxygen decoupling capability, and NaBH4 solution is 5~15g:200mL:200mL. The metal salt solution with oxygen decoupling capability includes Cu, Co or Mn, and the concentration of the metal salt solution with oxygen decoupling capability is 20~30 mmol / L. The mass concentration of the NaBH4 solution is 1-2%; In step 3), the calcination temperature is 800~1000℃; the calcination time is 1~3h.

2. The method for preparing MOFs-derived oxygen decoupling carriers according to claim 1, characterized in that, In step 1), the mixing is carried out by stirring, the mixing temperature is 15~40℃, and the mixing time is 10~50min; The hydrothermal reaction temperature is 140~180℃, and the hydrothermal reaction time is 6~10h.

3. The method for preparing MOFs-derived oxygen decoupling carriers according to claim 2, characterized in that, In step 2), the mixing is carried out by stirring for 30 to 120 minutes at a temperature of 20 to 40°C.

4. The method for preparing MOFs-derived oxygen decoupling carriers according to claim 3, characterized in that, In steps 1) and 2), the centrifugation speed is independently 8000~12000 r / min, and the centrifugation time is independently 3~7 min.

5. The method for preparing MOFs-derived oxygen decoupling carriers according to claim 4, characterized in that, In steps 1) and 2), the drying temperature is independently 90~120℃, and the drying time is independently 10~14h.

6. The application of a MOF-derived oxygen decoupling carrier prepared by the preparation method according to any one of claims 1 to 5 in the oxygen decoupling steam reforming of bioethanol chemical chain for hydrogen production.

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