Oxygen storage-sulfur resistance-sulfur storage multifunctional oxygen carrier and preparation method thereof

Abstract

The invention discloses an oxygen storage-sulfur resistance-sulfur storage multifunctional oxygen carrier and a preparation method thereof, and relates to the technical field of chemical looping. The general formula of the oxygen carrier is 3wt% NixN / LaMO3, and N is Mo, W, Fe or Zn; m is Fe, Mn, Co or Cr; x is equal to 1-4. The oxygen carrier designed and prepared by the invention has excellent reaction activity, and the conversion rate of CH4 reaches 99%. The sulfur-resistant steel has excellent sulfur resistance and thermal stability, and can stably serve for more than 50 times of redox cycles in a 50ppm H2S atmosphere. The sulfur storage capacity is excellent, and almost all H2S in a gas source can be adsorbed and stored. The oxygen carrier has excellent desulfurization capacity, and sulfur-containing substances stored in the oxygen carrier can be removed in the form of SO2 through O2 oxidation. The oxygen carrier has excellent reproducibility, and the same oxygen carrier still has the capability of recovering to fresh activity after being vulcanized and regenerated for multiple times.

Description

Technical Field

[0001] This invention relates to the field of chemical chain technology, and more specifically to a multifunctional oxygen carrier that stores oxygen, resists sulfur, and stores sulfur, and its preparation method. Background Technology

[0002] Syngas and hydrogen are important chemical feedstocks, used in methanol production, Fischer-Tropsch synthesis, hydroformylation, and carbonylation to synthesize high-value-added products. Conventional technologies typically use coal, natural gas, biomass gas, and industrial waste gas as feedstocks. However, these feedstocks often contain acidic impurities such as H2S, which can severely poison the catalysts involved in the production process. Furthermore, the presence of CO2 in the feedstocks or generated from water-steam shift reactions can affect the synthesis of downstream products and the purity of hydrogen. CO2 removal is also a necessary step, but the waste heat generated by desulfurization and decarbonization steps is large but of low quality and difficult to recover. Optimizing the production route through chemical looping technologies (such as methane chemical looping dry reforming, methane chemical looping steam reforming, and chemical looping water-steam shift reactions) to minimize the need for desulfurization and decarbonization steps is a feasible option.

[0003] The key to desulfurization and decarbonization through chemical looping technology lies in the design and preparation of the oxygen carrier. This requires the oxygen carrier to not only have excellent oxygen storage capacity but also sulfur storage function, i.e., the ability to adsorb sulfur impurities. Perovskite oxides, due to their stable crystal structure, strong oxygen carrying capacity during redox processes, and ability to maintain good structural integrity even under multiple cyclic reaction conditions, have received widespread attention in chemical looping-related technologies in recent years. Among them, lanthanide perovskites, as a typical perovskite oxide, have the advantages of readily available raw materials, relatively mature preparation processes, and good anti-sintering properties. They exhibit high structural stability and reversibility during redox cycles and have been widely used in technologies such as chemical looping combustion and chemical looping reforming as oxygen carriers or functional oxide materials. Furthermore, in the field of desulfurization, lanthanide perovskites are commonly used as high-temperature desulfurizing agents or oxidative desulfurization catalysts, suitable for the removal of sulfur-containing gases (such as H2S and SO2) and organic sulfides, achieving desulfurization under high-temperature conditions and regenerating through oxidation.

[0004] Despite the numerous advantages of lanthanide perovskites for chemical looping, their conversion capabilities for reactants such as CH4, CO2, and H2O are relatively low, necessitating modification to enhance these capabilities. Ni has been proven to be one of the most reactive metal elements in CO2 and CH4 reforming reactions, and studies have successfully loaded Ni onto perovskite surfaces to perform chemical looping. While adding Ni significantly enhances the CH4 conversion ability of lanthanide perovskites, the presence of H2S poses a significant challenge to the stable operation of Ni-based oxygen carriers. Therefore, developing oxygen carriers with active sites resistant to sulfur and a sulfur-storing support is crucial.

[0005] Addressing the critical challenge that acidic impurities such as H2S in gas sources like natural gas, biomass, and industrial waste gas can easily poison the active sites of oxygen carriers, and that strict requirements are placed on the desulfurization of the products, this invention designs and prepares a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage capabilities. This enables the efficient and pure conversion of sulfur-containing gas sources, providing a reliable solution for complex gas sources. Summary of the Invention

[0006] In view of this, the present invention provides a multifunctional oxygen carrier that stores oxygen, resists sulfur, and stores sulfur, and its preparation method, in order to achieve the following objectives: To address the high energy consumption issues caused by desulfurization and decarbonization steps in conventional syngas and hydrogen production processes, the production route can be optimized through chemical looping technology. This requires the oxygen carrier to possess both oxygen and sulfur storage capabilities to produce sulfur-free products. This invention aims to design and prepare an oxygen carrier with both high oxygen and sulfur storage capabilities.

[0007] The feedstocks commonly used in the production of syngas and hydrogen often contain acidic impurities such as H2S. When using chemical looping technology to process feedstock gases that have not undergone deep desulfurization, H2S is easily adsorbed onto the oxygen carrier to form stable sulfides, thus causing oxygen carrier poisoning. This invention aims to design and prepare an oxygen carrier with high tolerance to sulfur impurities.

[0008] This invention also aims to provide a design strategy that integrates oxygen storage, sulfur resistance, and sulfur storage, enabling the oxygen carrier to have multiple functions of oxygen storage, sulfur resistance, and sulfur storage.

[0009] This invention aims to provide a simple, reproducible, and large-scale production preparation method, which facilitates the mass production and practical engineering application of oxygen carriers, and provides a reliable solution for the high-quality conversion of low-carbon energy under complex gas sources.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A multifunctional oxygen carrier that stores oxygen, resists sulfur, and stores sulfur, wherein the general formula of the oxygen carrier is 3wt%Ni x N / LaMO3, wherein N is any one of Mo, W, Fe or Zn; M is any one of Fe, Mn, Co or Cr; and x takes the value 1-4. In the oxygen carrier, Ni reacts with N to form Ni in situ under H2 reduction conditions. x Ni alloy, the Ni x Nitrogen alloy is used as the active component for CH4 activation and to provide sulfur-resistant active sites; LaMO3 has oxygen and sulfur storage functions, capable of supplying oxygen for the main reaction while simultaneously adsorbing, removing, and storing H2S from the gas source. The preparation method of the above-mentioned multifunctional oxygen carrier (oxygen-sulphur-resistant-sulfur-storage) includes the following steps: Preparation of LaMO3: (1) According to the molar ratio La3+ :M + =1:1, add the required amount of La(NO3)3·6H2O and the metal salt corresponding to M to deionized water, and stir thoroughly to obtain the precursor solution; (2) Stir the precursor solution thoroughly in a water bath; (3) After stirring thoroughly, add citric acid in an amount that is 1.25 times the amount of metal cations in LaMO3; (4) Increase the water bath temperature and continue stirring until the precursor becomes stringy; (5) Dry the precursor and set aside for later use; (6) Take it out, grind it into powder, and roast it in a muffle furnace to obtain LaMO3; 3wt%Ni x Preparation of N / LaMO3: (7) According to the molar ratio Ni 2+ :N + =x, the required amount of N added to deionized water + The corresponding metal salt was thoroughly stirred to obtain precursor solution A; (8) According to the molar ratio Ni 2+ :N + =x, and continue to add the required amount of Ni(NO3)2·6H2O to the precursor solution A, and stir thoroughly to obtain the precursor solution B; (9) Prepared according to the 3wt% Ni x N / LaMO3 sample mass: PVP = 3:1. Add the required amount of PVP to precursor solution B and stir thoroughly to obtain precursor solution C. (10) According to the mass ratio Ni x N:LaMO3 = 0.03:0.97. Add the required amount of LaMO3 to the precursor solution and stir thoroughly until the liquid phase is completely evaporated. (11) Dry the precursor after the liquid phase has been completely evaporated and set aside for later use; (12) Take out the powder, transfer it to a muffle furnace for calcination, granulate the fully calcined sample, and place it in a tube furnace for calcination to obtain the oxygen storage-sulfur resistance-sulfur storage multifunctional oxygen carrier.

[0011] Preferably, in step (2), the water bath temperature is raised from 20°C to 50°C, and the heating time is 20 minutes.

[0012] Preferably, in step (4), the water bath temperature is increased to 70°C.

[0013] Preferably, the drying in step (5) is performed in a drying oven at 120°C for 12 hours.

[0014] Preferably, the roasting in the muffle furnace in step (6) is specifically as follows: the temperature is increased to 500°C at a heating rate of 5°C / min and held for 3 hours, and then the temperature is increased to 800°C at a heating rate of 10°C / min and held for 3 hours.

[0015] Preferably, the drying in step (11) is performed in a drying oven at 60°C for 12 hours.

[0016] Preferably, the roasting in the muffle furnace in step (12) specifically involves heating to 600°C at a heating rate of 5°C / min and holding for 3 hours.

[0017] Preferably, the calcination in the tubular furnace in step (12) is specifically as follows: under N2 atmosphere protection, the temperature is raised to 600°C at a heating rate of 5°C / min, then switched to 10% H2 / N2 for 30 min, and then switched to 5% CO2 / N2 for 30 min.

[0018] The sulfur resistance performance of the multifunctional oxygen carrier (oxygen storage-sulfur resistance-sulfur storage) was evaluated in both the reduction and oxidation reactors at 800℃. The reduction reactor contained different concentrations of H2S (50 and 1000 ppm, respectively). In the reduction reactor, CH4 gas containing H2S was partially oxidized to syngas by the oxygen carrier; in the oxidation reactor, the reduced oxygen carrier was oxidized by CO2 to replenish lattice oxygen. The initial volume concentration of CH4 was 5%, which decreased to 3.53% after mixing with H2S, with a flow rate of 130 mL / min; the volume concentration of CO2 was 4.5%, with a flow rate of 130 mL / min.

[0019] The desulfurization performance evaluation of the multifunctional oxygen carrier (oxygen storage, sulfur resistance, sulfur storage) was conducted in both the reduction and oxidation reactors at 800℃. In the reduction reactor, CH4 gas was partially oxidized to syngas by the oxygen carrier; in the oxidation reactor, the reduced oxygen carrier was oxidized by O2 to replenish lattice oxygen, while the sulfur-containing substances stored in the oxygen carrier were oxidized and removed in the form of SO2. The initial volume concentration of CH4 was 5%, the flow rate was 100 mL / min, and the reaction time was 6 min; the volume concentration of O2 was 4.5%, the flow rate was 130 mL / min, and the reaction time was 12 min, with the cycle repeated 5 times.

[0020] As can be seen from the above technical solution, compared with the prior art, the present invention has the following technical effects: 1. The oxygen carrier designed and prepared in this invention has excellent reactivity, with a CH4 conversion rate of 99%.

[0021] 2. It possesses excellent sulfur resistance and thermal stability, and can stably operate for more than 50 redox cycles in an atmosphere of 50ppmH2S.

[0022] 3. It has excellent sulfur storage capacity, and can adsorb and store almost all H2S in the gas source.

[0023] 4. It has excellent desulfurization capabilities, and can remove sulfur-containing substances stored in the oxygen carrier in the form of SO2 via O2.

[0024] 5. It has excellent regenerative capacity. After undergoing multiple sulfurization and regeneration processes, the same oxygen carrier can still be restored to its fresh state of activity. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. Figure 1 In the image, (a) shows the prepared 3 wt% Ni / LaFeO3 and 3 wt% Ni x XRD patterns of Mo / LaFeO3 (x=1-4), (b) XPS patterns of 3 wt% Ni / LaFeO3 and 3 wt% Ni3Mo / LaFeO3, and (c) XPS patterns of 3 wt% Ni / LaFeO3 and 3 wt% Ni3Mo / LaFeO3 under 50ppm H2S atmosphere. x CH4-TPR with Mo / LaFeO3 oxygen carrier, (d) is the ignition temperature of CH4 in CH4-TPR and the temperature at which H2 / CO=2, (e) is the temperature at 800℃ for CH4 (50ppmH2S) and CO2 with 3 wt%Ni / LaFeO3 and 3 wt%Ni x Evolution of gaseous products during the reaction of Mo / LaFeO3 series oxygen carriers, (f) 3 wt% Ni / LaFeO3 and 3 wt% Ni in the isothermal reaction. x CH4 conversion, H2 yield and CO yield of Mo / LaFeO3.

[0026] Figure 2 (a) shows the sulfur resistance test of 3 wt% Ni / LaFeO3 and 3 wt% Ni3Mo / LaFeO3 in the presence of 50 ppm H2S; (b) shows the sulfur resistance test of 3 wt% Ni / LaFeO3 and 3 wt% Ni3Mo / LaFeO3 in the presence of 1000 ppm H2S; (c) shows the sulfur resistance test of the sulfurized oxygen carrier after regeneration by individually introducing different gases; and (d) shows the sulfur resistance test of the sulfurized oxygen carrier after regeneration by alternately introducing different gases.

[0027] Figure 3(a) shows the sulfur storage performance test of 3 wt% Ni3Mo / LaFeO3, (b) shows the desulfurization performance test of 3 wt% Ni3Mo / LaFeO3, (c) shows the stability test of 3 wt% Ni3Mo / LaFeO3 in a 50ppm H2S atmosphere, and (d) shows the stability test of 3 wt% Ni3Mo / LaFeO3 in a 1000ppm H2S atmosphere. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] 1. Examples of oxygen carrier preparation: Example 1: Preparation of LaFeO3: (1) According to the molar ratio La 3+ :Fe 3+ In a 1:1 ratio, add the required amounts of La(NO3)3·6H2O and Fe(NO3)3·9H2O to deionized water and stir thoroughly to obtain the precursor solution. (2) Stir the precursor solution thoroughly at 20°C. When the water bath temperature rises to 50°C, add citric acid in an amount that is 1.25 times the amount of cationic substance in LaMO3. (3) Heat the water bath to 70°C and stir continuously until the precursor becomes stringy; (4) Transfer the precursor to a drying oven at 120°C and dry for 12 hours; (5) Take out the powder, transfer it to a muffle furnace, heat it to 500℃ at a heating rate of 5℃ / min and hold it for 3h, then heat it to 800℃ at a heating rate of 10℃ / min and hold it for 3h, finally obtaining black powdered LaFeO3.

[0030] Example 2: Preparation of 3wt% Ni / LaFeO3: (1) Add the required amount of Ni(NO3)2·6H2O to deionized water and stir thoroughly to obtain precursor solution A; (2) According to the prepared 3wt% Ni / LaFeO3 sample mass: PVP=3:1, add the required amount of PVP to the precursor solution A and stir thoroughly to obtain precursor solution B; (3) Add the required amount of LaFeO3 as described in Example 1) to the precursor solution B according to the mass ratio Ni:LaFeO3=0.03:0.97, and stir thoroughly until the liquid phase is completely evaporated; (4) Place the completely evaporated precursor in a drying oven at 60℃ and dry for 12 hours; (5) Take out the powder, transfer it to a muffle furnace, heat it to 600℃ at a heating rate of 5℃ / min and hold it for 3h; (6) After the fully calcined sample is granulated, it is placed in a tube furnace and heated to 600°C at a heating rate of 5°C / min under N2 atmosphere protection. Then, it is switched to 10% H2 / N2 and kept at that temperature for 30 min, followed by 5% CO2 / N2 and kept at that temperature for 30 min.

[0031] Example 3: Preparation of 3wt% Ni3Mo / LaFeO3: (1) According to the molar ratio Ni 2+ Mo 6+ Add the required amount of (NH4)6Mo7O to deionized water at a ratio of 3:1. 24 ·4H2O, stir thoroughly to obtain precursor solution A; (2) According to the molar ratio Ni 2+ Mo 6+ With a ratio of 3, the required amount of Ni(NO3)2·6H2O is added to the precursor solution A, and the mixture is stirred thoroughly to obtain the precursor solution B. (3) According to the prepared sample mass: PVP=3:1, add the required amount of PVP to the precursor solution B and stir thoroughly to obtain the precursor solution C; (4) Add the required amount of LaFeO3 in Example 1 to the precursor solution according to the mass ratio Ni3Mo:LaFeO3=0.03:0.97, and stir thoroughly until the liquid phase is completely evaporated; (5) Place the completely evaporated precursor in a drying oven at 60℃ and dry for 12 hours; (6) Take out the powder, transfer it to a muffle furnace, heat it to 600℃ at a heating rate of 5℃ / min and hold it for 3h; (7) After the fully calcined sample is granulated, it is placed in a tube furnace and heated to 600°C at a heating rate of 5°C / min under N2 atmosphere protection. Then, it is switched to 10% H2 / N2 and kept at that temperature for 30 min, and then switched to 5% CO2 / N2 and kept at that temperature for 30 min.

[0032] 3wt% NiMo / LaFeO3, 3wt% Ni2Mo / LaFeO3, and 3wt% Ni4Mo / LaFeO3 were prepared using the same method.

[0033] Example 4: Characterization of oxygen carriers The 3wt% Ni / LaFeO3 and 3wt% Ni prepared in Examples 2 and 3 were used. xXRD analysis was performed on Mo / LaFeO3 (x=1-4), and XPS analysis was performed on the prepared 3wt% Ni / LaFeO3 and 3wt% Ni3Mo / LaFeO3. The results are as follows: Figure 1 As shown in a and b.

[0034] In the XRD pattern of 3wt% Ni / LaFeO3, characteristic peaks of elemental Ni were clearly observed near 44.5°. Meanwhile, in 3wt% Ni... x The diffraction peaks of Mo / LaFeO3 (x=1-4) at this position show a regular shift with the concentration of Ni. In addition, in the 3p orbitals of Ni, it was found that the binding energy of Ni metal in 3wt%Ni3Mo / LaFeO3 shifted to a higher binding energy compared to 3wt%Ni / LaFeO3, which proved the formation of NiMo alloy and the transfer of electrons from Ni elemental to Mo.

[0035] 2. Examples of oxygen carrier activity evaluation: Example 4: CH4+H2S-TPR Heating stage: The 3wt% Ni / LaFeO3 and 3wt% Ni prepared in Examples 2 and 3 are heated together. x Mo / LaFeO3 (x=1-4) were loaded into fixed-bed reactors and heated from room temperature to 800°C at a rate of 10°C / min under an atmosphere of 5% CH4 gas (100 mL / min) and 50 ppm H2S (30 mL / min). Changes in CH4, H2, CO and CO2 in the exhaust gas were monitored.

[0036] The changes in CH4, H2, CO, and CO2 during the temperature-programmed reduction of CH4 in the presence of 50 ppm H2S are as follows: Figure 1 As shown in Figure c, it can be seen that when the reaction temperature rises above 700℃, the CH4 concentration in the 3% Ni / LFO sample decreases sharply, while the concentrations of H2 and CO increase. This indicates that at relatively low temperatures, CH4 may be partially oxidized to CO and H2 by 3wt% Ni / LaFeO3. Notably, when the temperature exceeds 600℃, a sharp decrease in CH4 concentration is observed on 3wt% Ni3Mo / LaFeO3, accompanied by the formation of H2 and CO. Conversely, the CO concentration initially rises to approximately 1.5%, then decreases, then rises again, and then decreases again. Only when the temperature exceeds 700℃ does it begin to rise continuously. This phenomenon may be attributed to the slow lattice oxygen migration rate at lower temperatures. A series of ignition temperatures for oxygen supports and the temperature situation when H2 / CO = 2 are shown in the figure. Figure 1As shown in Figure d, the appropriate addition of Mo significantly reduced the ignition temperature of CH4, which may be attributed to the specific Ni content. x The Mo alloy structure enhances the activation ability of CH4.

[0037] Example 5: Isothermal Reaction The 3wt% Ni / LaFeO3 and 3wt% Ni prepared in Examples 2 and 3 were used. x Mo / LaFeO3 (x=1-4) were respectively loaded into a fixed-bed reactor and heated from room temperature to 800°C under N2 atmosphere at a heating rate of 10°C / min.

[0038] Reduction reaction stage: 5% CH4 gas (100 mL / min) and 50 ppm H2S (30 mL / min) were introduced, the reaction temperature was maintained at 800°C, the reaction time was 6 min, and the concentration of CH4 in the tail gas and the concentration of the product were recorded.

[0039] Nitrogen purging stage: Close the CH4 gas line and switch to pure N2 gas (70 mL / min) for 10 min to remove residual gas in the pipeline and reactor, avoid cross-contamination between different gases, and ensure that each stage is carried out in an optimized manner.

[0040] Oxidation reaction stage: Close the N2 gas path and switch to 5% CO2 gas (130 mL / min). Regenerate the oxygen carrier at the same temperature for 12 min, so that the reduced oxygen carrier is reoxidized to restore its initial state for the next cycle.

[0041] Figure 1 Figure e shows the results of the isothermal reaction of CH4 with 3% Ni / LaFeO3 and 3% NixMo / LaFeO3 (1-4) in the presence of 50 ppm H2S. When CH4 + H2S is introduced into the reactor, the conversion of CH4 is immediately observed, leading to a sharp increase in the concentrations of H2 and CO. Furthermore, a small amount of CO2 is produced when methane is completely combusted with the oxygen carrier. Compared to 3% Ni / LaFeO3, 3% Ni3Mo / LaFeO3 produces more CO and H2 while generating less CO2, indicating that more lattice oxygen is available for the partial oxidation reaction. The CH4 conversion and the yields of CO and H2 for a series of oxygen carriers in the methane partial oxidation step are shown in the figure. Figure 1 As shown in Figure f, both the CH4 conversion rate and CO yield decreased with increasing Mo content. After comprehensive consideration, 3% Ni3Mo / LaFeO3 was selected as the oxygen carrier for subsequent sulfur resistance studies.

[0042] 3. Example of evaluating the sulfur resistance performance of oxygen carrier: Example 6: Evaluation of the sulfur resistance of oxygen carrier The toxicity of H2S to oxygen carriers is not immediate, but rather a gradual decline in performance during redox cycles. Redox cycles were conducted on 3% Ni / LaFeO3 and 3% Ni3Mo / LaFeO3 prepared in Examples 2 and 3, respectively, in the presence of different concentrations of H2S.

[0043] Redox cycle: Repeat the reduction and oxidation reaction stages in Example 5, 50 times under a 50 ppm H2S atmosphere and 20 times under a 1000 ppm H2S atmosphere.

[0044] Operation with different H2S concentrations: H2S in the reduction stage is replaced with 1000ppm H2S.

[0045] Based on CH4+H2S-TPR experiments and 800℃ heat preservation experiments, 3%Ni / LaFeO3 and 3%Ni3Mo / LaFeO3 were selected as oxygen carriers for studying sulfur resistance performance, and their respective sulfur resistance performance evaluation results are presented, such as... Figure 2 As shown in Figures a and b, since the yield trends of CO and H2 are consistent with those of CH4 conversion, the CH4 conversion is the primary focus of this discussion. During continuous redox cycles in a 50 ppm H2S atmosphere, the activity of the 3% Ni3Mo / LaFeO3 sample decreased slightly. After 50 cycles, the CH4 conversion decreased from 99.25% to 94.77%, while the 3% Ni / LaFeO3 sample showed a significant decrease (31.03%). A similar trend was observed in the sulfur resistance test in a 1000 ppm H2S atmosphere. The CH4 conversion of 3% Ni3Mo / LaFeO3 decreased by 6.46%, while 3% Ni / LaFeO3 suffered more severe sulfurization deactivation (a decrease of 41.11%). This indicates that the formation of the NiMo alloy effectively delayed the sulfurization deactivation of the oxygen carrier.

[0046] Example 7: Regeneration of oxygen carrier after sulfidation The 3% Ni3Mo / LaFeO3 after sulfurization (1000ppm) in Example 6 was treated with different atmospheres, and then the sulfur resistance test of Example 6 was continued on the treated oxygen carrier.

[0047] Different atmosphere operation: O2, H2 and CO were introduced separately at 130 ml / min for 1 h; CH4 (100 ml / min, 6 min) and O2 (130 ml / min, 12 min), CH4 and H2O and H2 and O2 were introduced alternately for 5 cycles, with N2 purging during the switching of gases.

[0048] Figure 2Figures c and d show the sulfur resistance performance evaluation of the oxygen carrier after sulfurization regeneration. The oxygen carrier regenerated by a single gas showed poor performance, failing to recover to its initial state, and its sulfur resistance decreased. The CH4 conversion rate continued to decline in subsequent sulfur resistance tests. The oxygen carrier regenerated by alternating introduction of CH4 and H2O, and H2 and O2, also failed to recover its performance. However, the oxygen carrier regenerated by CH4 and O2 almost recovered to its fresh state and also exhibited excellent sulfur resistance in subsequent sulfur resistance tests.

[0049] 4. Sulfur storage and desulfurization performance of oxygen carriers Example 8: Sulfur Storage Performance Test The 3wt% Ni3Mo / LaFeO3 prepared in Example 3 was loaded into a fixed-bed reactor and heated from room temperature to 800°C under a N2 atmosphere at a heating rate of 10°C / min.

[0050] Reduction reaction stage: 5% CH4 gas (90 mL / min) and 1000 ppm H2S (40 mL / min) were introduced, the reaction temperature was maintained at 800℃, the reaction time was 20 min, the concentration of CH4 in the tail gas and the concentration of the product were recorded, and the concentration of H2S was monitored by mass spectrometry.

[0051] Nitrogen purging stage: Close the CH4 and H2S gas lines and switch to pure N2 gas (70 mL / min) for 10 min to remove residual gas in the pipelines and reactor and avoid cross-contamination between different gases.

[0052] Oxidation reaction stage: Close the N2 gas circuit and switch to 5% CO2 gas (130 mL / min). Regenerate the oxygen carrier at the same temperature for 30 min. Record the CO2 concentration and the concentration of the product. Monitor the SO2 concentration using a mass spectrometer.

[0053] Figure 3 Figures a and b show the curves of reactants and products in a single sulfur resistance cycle test of 3wt% Ni3Mo / LaFeO3. After H2S was introduced into the reactor, its concentration immediately decreased sharply and approached 0 ppm over time, indicating that 3wt% Ni3Mo / LaFeO3 can effectively remove H2S from the gas source. Meanwhile, no SO2 gas was observed to be generated in the subsequent oxidation reactor, indicating that the removed sulfur-containing substances cannot be oxidized to SO2 by CO2.

[0054] Example 9: Desulfurization performance test The 3wt% Ni3Mo / LaFeO3 (50ppm) sulfurized in Example 6 was regenerated using the alternating CH4 and O2 regeneration method described in Example 7. The SO2 concentration was monitored throughout the regeneration process, and the results are as follows: Figure 3As shown in b.

[0055] No SO2 generation was observed during the CH4 reaction stage. However, when O2 was introduced into the reactor, a large amount of SO2 was immediately generated, exceeding 3000 ppm, indicating that sulfur-containing substances stored on the surface of the oxygen carrier could be removed as SO2 by O2.

[0056] 5. Oxygen carrier stability test Example 10: The 3wt% Ni3Mo / LaFeO3 prepared in Example 3 was evaluated for sulfur resistance according to Example 6. After sulfurization, the oxygen carrier was regenerated by alternately introducing CH4 and O2 as in Example 7. The regenerated oxygen carrier was then subjected to further sulfur resistance testing. This regeneration process was repeated multiple times, and the data obtained are as follows: Figure 3 As shown in c and d.

[0057] Stability test under 50ppm H2S atmosphere, as follows Figure 3 As shown in Figure c, the performance of the oxygen carrier slightly decreases after 50 cycles, but can be restored to its fresh state performance after regeneration; the stability test under a 1000ppm H2S atmosphere is as follows. Figure 3 As shown in Figure d, a significant performance decrease was observed after 30 cycles. However, the performance could be restored to its fresh state after regeneration. Moreover, the performance could be restored to its original state after multiple regenerations, indicating that 3wt%Ni3Mo / LaFeO3 can operate stably according to the regeneration process mentioned in this invention.

[0058] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multifunctional oxygen carrier that combines oxygen storage, sulfur resistance, and sulfur storage, characterized in that, The oxygen carrier has the general formula 3wt%Ni x N / LaMO3, wherein N is any one of Mo, W, Fe or Zn; M is any one of Fe, Mn, Co or Cr; and x takes the value 1-4; in the oxygen carrier, Ni and N are in situ converted to Ni under H2 reduction conditions. x Ni alloy, the Ni x N alloy is used as an active component for CH4 activation and provides sulfur-resistant active sites; LaMO3 has oxygen and sulfur storage functions, and can supply oxygen for the main reaction while adsorbing, removing and storing H2S in the gas source.

2. A method for preparing the multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage as described in claim 1, characterized in that, Includes the following steps: Preparation of LaMO3: (1) According to the molar ratio La 3+ :M + =1:1, add the required amount of La(NO3)3·6H2O and the metal salt corresponding to M to deionized water, and stir thoroughly to obtain the precursor solution; (2) Stir the precursor solution thoroughly in a water bath; (3) After stirring thoroughly, add citric acid in an amount that is 1.25 times the amount of metal cations in LaMO3; (4) Increase the water bath temperature and continue stirring until the precursor becomes stringy; (5) Dry the precursor and set aside for later use; (6) Take it out, grind it into powder, and roast it in a muffle furnace to obtain LaMO3; 3wt%Ni x Preparation of N / LaMO3: (7) According to the molar ratio Ni 2+ :N + =x, the required amount of N added to deionized water + The corresponding metal salt was thoroughly stirred to obtain precursor solution A; (8) According to the molar ratio Ni 2+ :N + =x, and continue to add the required amount of Ni(NO3)2·6H2O to the precursor solution A, and stir thoroughly to obtain the precursor solution B; (9) Prepared according to the 3wt% Ni x N / LaMO3 sample mass: PVP = 3:

1. Add the required amount of PVP to precursor solution B and stir thoroughly to obtain precursor solution C. (10) According to the mass ratio Ni x N:LaMO3 = 0.03:0.

97. Add the required amount of LaMO3 to the precursor solution and stir thoroughly until the liquid phase is completely evaporated. (11) Dry the precursor after the liquid phase has been completely evaporated and set aside for later use; (12) Take out the powder, transfer it to a muffle furnace for calcination, granulate the fully calcined sample, and place it in a tube furnace for calcination to obtain the oxygen storage-sulfur resistance-sulfur storage multifunctional oxygen carrier.

3. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 2, characterized in that, In step (2), the water bath temperature is increased from 20℃ to 50℃, and the heating time is 20min.

4. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 3, characterized in that, In step (4), the water bath temperature is further increased to 70°C.

5. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 2, characterized in that, The drying process described in step (5) involves drying in a drying oven at 120°C for 12 hours.

6. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 2, characterized in that, The specific steps of roasting in the muffle furnace in step (6) are as follows: heating to 500℃ at a heating rate of 5℃ / min and holding for 3 hours, followed by heating to 800℃ at a heating rate of 10℃ / min and holding for 3 hours.

7. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 2, characterized in that, The drying process described in step (11) involves drying in a drying oven at 60°C for 12 hours.

8. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 2, characterized in that, The roasting in the muffle furnace in step (12) specifically involves heating to 600°C at a heating rate of 5°C / min and holding for 3 hours.

9. The method for preparing a multifunctional oxygen carrier with oxygen storage, sulfur resistance, and sulfur storage according to claim 8, characterized in that, The calcination in the tubular furnace in step (12) is as follows: under N2 atmosphere protection, the temperature is raised to 600℃ at a heating rate of 5℃ / min, then switched to 10% H2 / N2 and held for 30min, and then switched to 5% CO2 / N2 and held for 30min.

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