A rare earth coordination-based anti-poisoning self-repairing catalyst and its application in bio-jet fuel

Abstract

The application relates to the technical field of renewable bio-energy, in particular to a rare earth coordination-based anti-poisoning self-repairing catalyst and application of the catalyst in bio-jet fuel, wherein the catalyst is a Co-Ce bimetallic system loaded with a layered double hydroxide derivative composite oxide, the MgAl-LDH calcination product with a memory effect is used as a carrier, Co nanoparticles are used as main active metals, Ce 3+ / Ce 4+ Oxidation-reduction pairs are anti-poisoning self-repairing assistants. First, Ce 3+ is used to protect Co active sites by preferentially coordinating with sulfur / nitrogen poisons, then, in the oxygen-containing and regeneration stages, the memory effect of the LDH carrier is used to induce Ce species to redisperse, and Ce 4+ is reduced to Ce 3+ , the poisons are released, and activity regeneration is completed. In summary, the application solves the technical problem that existing hydrogen-deoxidization catalysts are easily poisoned and deactivated by sulfur and nitrogen impurities and cannot be regenerated in situ, and can greatly improve the economy of bio-jet fuel production.

Description

Technical Field

[0001] This application relates to the field of renewable bioenergy technology, and more specifically, it relates to a rare earth coordination-based anti-poisoning self-healing catalyst and its application in bio-jet fuel. Background Technology

[0002] Bio-jet fuel, as an important source of sustainable aviation fuel, has a core process that converts waste oils into C2O2 through hydrodeoxygenation. 15-18 For straight-chain alkanes, the hydrodeoxygenation catalyst is crucial in this process, with Ni-Mo / γ-Al₂O₃ or Co-Mo / γ-Al₂O₃ systems commonly used industrially. However, waste oils inevitably contain sulfur and nitrogen impurities, which strongly adsorb onto the active metal surface of the catalyst, leading to permanent catalyst deactivation. This has always been a major technical bottleneck restricting the economic viability of bio-jet fuel.

[0003] In existing technologies, the development of sulfur- and nitrogen-resistant catalysts mainly focuses on two paths: one is to add rare earth Ce or La as promoters, taking advantage of the preferential coordination of rare earth ions with sulfur and nitrogen, sacrificing themselves to protect the main active metal; the other is to introduce phosphides or nitrides into the catalyst to improve its tolerance. However, these methods still have significant drawbacks:

[0004] First, the sacrificial protection effect of rare earth ions is irreversible. Once rare earths coordinate with poisons to form stable compounds, they themselves become deactivated and cannot be regenerated in situ, resulting in a limited overall lifespan for the catalyst.

[0005] Secondly, existing catalyst regeneration usually requires complex steps such as shutdown, unloading, high-temperature roasting or acid washing, which results in high operating costs. Furthermore, after multiple regenerations, the active metal sinters and cannot restore the initial activity.

[0006] Third, and more importantly, there is still no method that can utilize the reversible cycle of rare earth valence states (Ce). 3+ / Ce 4+ A catalyst system that achieves continuous regeneration through "poisoning-self-repair" during operation.

[0007] Therefore, the urgent technical problem to be solved in this field is: how to repair the catalyst poisoned by sulfur and nitrogen in situ through its own reaction without interrupting the reaction. Based on this, this application provides a rare earth coordination-based anti-poisoning self-healing catalyst and its application in bio-jet fuel. Summary of the Invention

[0008] To address the aforementioned technical problems, this application provides a rare-earth coordination-based anti-poisoning self-healing catalyst and its application in bio-jet fuel. Cerium is used as a reversible sacrificial anti-poisoning component, and the memory effect of layered bimetallic hydroxides is utilized to drive the Ce244-C ... 3+ / Ce4+ Through recycling, in-situ self-repair of the hydrodeoxygenation catalyst under sulfur and nitrogen conditions was successfully achieved.

[0009] In the first aspect, this application provides a rare earth coordination-based anti-poisoning self-healing catalyst, which adopts the following technical solution:

[0010] A rare-earth coordination-based anti-poisoning self-healing catalyst is a Co-Ce bimetallic system supported on a layered bimetallic hydroxide-derived composite oxide, comprising the following components:

[0011] Support: The support is a Mg(Al)O composite oxide obtained by calcination of MgAl-LDH;

[0012] Main active metal: The main active metal is Co, which exists in a zero-valence state and in nanoparticle form;

[0013] Additives: The additives are Ce 3+ Ce 4+ Ce exists in the form of redox pairs.

[0014] Preferably, the molar ratio of the main active metal Co to the auxiliary agent Ce is (1.5-2.5):1;

[0015] The amount of the main active metal Co is 6-10 wt% of the total mass of the catalyst.

[0016] The amount of additive Ce is 3-6 wt% of the total mass of the catalyst.

[0017] Preferably, the specific surface area of ​​the Mg(Al)O composite oxide is 180-250 m². 2 / g;

[0018] The pore volume is 0.4-0.7 cm. 3 / g.

[0019] Preferably, the molar ratio of Mg to Al in the Mg(Al)O composite oxide is (2-3):1.

[0020] Secondly, this application provides a method for preparing a rare earth coordination-based anti-poisoning self-healing catalyst, employing the following technical solution:

[0021] Synthesis of S1 and MgAl-LDH precursors:

[0022] Magnesium salts and aluminum salts were dissolved in water at the corresponding molar ratio using the urea hydrothermal coprecipitation method. Urea was added, and the mixture was refluxed and stirred at 90-100℃ for 20-30 h to obtain MgAl-LDH powder.

[0023] S2, Co / Ce co-impregnation: Cobalt salt and cerium salt are dissolved in water in the corresponding molar ratio, and the impregnation solution is added dropwise to the MgAl-LDH powder obtained in S1 using the equal volume impregnation method. The powder is then aged and dried.

[0024] S3, calcination: The product after drying S2 is calcined in sections in air at 500-600℃ for 3-5 h to obtain Co3O4 / CeO2 / Mg(Al)O composite oxide;

[0025] S4. Reduction and Activation: The Co3O4 / CeO2 / Mg(Al)O composite oxide obtained in S3 is reduced in a hydrogen-containing atmosphere at 350-450℃ for 3-5 h to obtain the active catalyst Co. 0 / Ce2O3 / Mg(Al)O.

[0026] Preferably, the specific process parameters are as follows:

[0027] The total molar ratio of urea to magnesium salt and aluminum salt in S1 is (2-4):1, the reflux stirring temperature is 95℃, and the reaction time is 24 h.

[0028] The heating rate of the calcination in S3 is 1-3℃ / min, and the specific segmented calcination process is as follows: hold at 350℃ for 1-3 h, and hold at 550℃ for 3-5 h.

[0029] Preferably, the cobalt salt in S2 is Co(NO3)2·6H2O, and the cerium salt is Ce(NO3)3·6H2O; the aging time after impregnation is 3-5 h, and the drying procedure is: 50-90℃, 1-2 h.

[0030] Thirdly, this application provides a method for preparing bio-jet fuel by hydrodeoxygenation of waste oil using any of the above-mentioned catalysts, comprising the following steps:

[0031] The reduced and activated catalyst was loaded into a fixed-bed reactor, hydrogen gas was introduced, and the temperature was raised to the reaction temperature of 250-300℃, the hydrogen pressure was 3-5 MPa, and the space velocity was 0.5-2.0 h⁻¹. -1 Waste oil is pumped into a reactor for hydrodeoxygenation to obtain C. 15- C 18 Alkane products;

[0032] The method also includes a self-repairing regeneration step for the catalyst: when the deoxygenation rate is detected to drop below 70% of the initial value, the oil feed is stopped, an oxygen-containing regeneration atmosphere is introduced, and the catalyst is treated at 300-400℃ for 1-4 hours. Then, the catalyst is switched back to a reducing atmosphere and reduced at 350-450℃ for 1-3 hours, thus completing the in-situ regeneration.

[0033] Preferably, the oxygen-containing regeneration atmosphere is a N2 mixture containing 0.1-1 vol% O2, with the balance being N2; the reducing atmosphere is a N2 mixture containing 5-15 vol% H2, with the balance being N2.

[0034] Fourthly, this application provides the application of an anti-poisoning self-healing hydrodeoxygenation catalyst in the preparation of bio-jet fuel, using the catalyst described in any of the above-mentioned preparation methods to obtain the product, or using any of the above-mentioned waste oil hydrodeoxygenation methods to prepare bio-jet fuel.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application constructs a three-in-one self-healing catalyst system of "LDH confined support-cobalt active center-cerium redox pair" by combining layered bimetallic hydroxide-derived composite oxide with cobalt (Co) as the main active metal and cerium (Ce) as a reversible sacrificial anti-poisoning agent. Under the synergistic effect, it realizes the in-situ "poisoning-regeneration" cycle in the hydrodeoxygenation reaction of sulfur- and nitrogen-containing waste oil, eliminating the complicated steps of shutdown and regeneration required by traditional catalysts.

[0037] 2. This application utilizes Ce 3+ / Ce 4+ The reversible redox properties of cerium, by using it as a sacrificial site for preferential coordination with sulfur and nitrogen impurities, endow the catalyst surface with self-healing capabilities to resist poisoning. When the reactants contain sulfur and nitrogen impurities, Ce... 3+ Preferentially coordinates with the toxicant to form Ce-S / Ce-N species, and is itself oxidized to Ce. 4+ This protects the main active metal Co. 0 Avoid being poisoned;

[0038] When regeneration is performed using a 0.1-1 vol% O2 / N2 oxygen-containing regeneration atmosphere, Ce 4+ Restored to Ce 3+ It also releases toxins, while the partial layered reconstruction of the LDH carrier helps Ce. 3+ The redispersion allows the catalyst to be regenerated in situ multiple times without unloading. As a result, the stable operating time of the catalyst in sulfur- and nitrogen-containing feedstocks is significantly extended, and the total lifespan is more than 5 times that of traditional Ni-Mo catalysts.

[0039] 3. The catalyst system in this application overcomes the shortcomings of existing hydrodeoxygenation catalysts, such as "easy permanent poisoning by sulfur and nitrogen and inability to be regenerated in situ," by virtue of its unique triple relay mechanism of "LDH memory effect - Ce valence state cycle - Co sulfur resistance and tolerance." The specific analysis is as follows:

[0040] First, the Mg(Al)O composite oxide formed after calcination of the LDH support retains part of the memory effect of the layered structure. During oxygen-containing regeneration, Mg(Al)O can be partially reconstructed into the LDH layered structure. This process is accompanied by the reinsertion of lattice water and hydroxyl groups, which helps to regenerate Ce. 3+ Evenly dispersed near the plate, preventing agglomeration and inactivation, thus achieving Ce 3+ / Ce 4+ Highly efficient reversibility of cycles;

[0041] Secondly, this application controls the molar ratio of the main active metal Co to the sacrificial agent Ce within the range of 1.5:1 to 2.5:1, with a Co content of 6-10 wt% and a Ce content of 3-6 wt%. This ratio ensures sufficient Ce content. 3+ Prioritizes the capture of sulfur and nitrogen toxins without diluting the surface Co due to excessive Ce. 0 Active sites ensure the optimal balance between deoxygenation activity and anti-poisoning ability;

[0042] Meanwhile, Co metal itself has better tolerance to sulfur than traditional Ni, and there is a strong electronic synergistic effect between Co and Ce, which significantly reduces the energy barrier of redox cycle, allowing the self-repair process to be completed quickly under relatively mild conditions. After regeneration, the deoxygenation rate is restored to more than 85% of the fresh state, and after 5 poisoning-regeneration cycles, it can still maintain a deoxygenation rate of more than 83%, which is far better than the group without LDH or without additives.

[0043] 4. The raw materials used in this application, such as Mg(NO3)2·6H2O, Al(NO3)3·9H2O, Co(NO3)2·6H2O, Ce(NO3)3·6H2O, urea, and guar gum powder, are all bulk chemicals or commonly used reagents. They are stable in source, inexpensive, and have simple preparation processes. They do not require expensive equipment or special operating conditions. The waste catalyst can be calcined at high temperature to remove carbon deposits and adsorbates, and then its activity can be restored by simple reduction. It can also be re-impregnated with Ce to replenish its activity, thus realizing a closed-loop operation mode of "operation-poisoning-in-situ regeneration-long-term service".

[0044] In summary, this application, through a triple integrated innovation of designing the memory effect of the LDH support, selecting the cobalt main active metal, and introducing a cerium reversible sacrificial anti-poisoning agent, has successfully achieved in-situ self-repair of the hydrodeoxygenation catalyst in the conversion of sulfur- and nitrogen-containing waste oils. This breakthrough overcomes the three major technical bottlenecks in the existing technology: "catalysts are easily and permanently poisoned by sulfur and nitrogen", "cannot be regenerated in situ", and "short lifespan requiring frequent replacement". It has great potential for industrial application of bio-jet fuel. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments.

[0046] Unless otherwise specified, the raw materials used in the embodiments of this application are not limited in origin from commercially available analytical grade or chemically pure materials, as shown in the table below:

[0047]

[0048] Performance testing test I

[0049] The rare-earth coordination-based anti-poisoning self-healing catalyst obtained in the examples was selected as the test object, and its following performance indicators were tested respectively:

[0050] 1) Deoxygenation rate determination: Gas chromatography (GC-FID) was used, with nonadecane as an internal standard, to calculate the molar percentage of fatty acids in the raw material converted into alkanes;

[0051] Deoxygenation rate = (Total carbon moles of alkanes in the product / Total carbon moles of fatty acids in the feedstock) × 100%;

[0052] The chromatographic conditions were as follows: HP-5 capillary column (30m×0.32mm×0.25μm), carrier gas N2 flow rate 1.0 mL / min, temperature program: 80℃ for 1 min, then increased to 280℃ at 10℃ / min and held for 10 min, injection port temperature 280℃, detector temperature 300℃.

[0053] 2) Determination of sulfur and nitrogen content: Sulfur content was determined by ultraviolet fluorescence method (ASTM D5453), and nitrogen content was determined by chemiluminescence method (ASTM D4629).

[0054] 3) X-ray photoelectron spectroscopy (XPS): used to determine Ce. 3+ / (Ce 3+ and Ce 4+ The ratio was determined using Al Kα rays (1486.6 eV), with C1s=284.8 eV correction. Tests were performed on a Thermo Scientific K-Alpha+ XPS. Samples were pre-treated with Ar... + Etch for 30 seconds to remove surface contaminants.

[0055] 4) Specific surface area and pore structure: The N2 adsorption-desorption (BET) method was used to determine the specific surface area at 77 K using a Micromeritics ASAP 2460 specific surface area analyzer. The samples were degassed at 200℃ for 4 h before testing.

[0056] 5) Catalyst activity evaluation: The evaluation was conducted in a fixed-bed reactor (10 mm inner diameter, 5 g catalyst loading). The reaction conditions were uniquely set as follows: temperature 280℃, hydrogen pressure 4 MPa, hydrogen-to-oil volume ratio 800:1, and mass hourly space velocity 1.0 h⁻¹. -1Each embodiment and comparative example was tested five times.

[0057] Example 1

[0058] A rare-earth coordination-based anti-poisoning self-healing catalyst is a Co-Ce bimetallic system supported on a layered bimetallic hydroxide-derived composite oxide, comprising the following components:

[0059] Support: The support is a Mg(Al)O composite oxide obtained by calcination of MgAl-LDH;

[0060] Main active metal: The main active metal is Co, which exists in a zero-valence state and in nanoparticle form;

[0061] Additives: The additives are Ce 3+ Ce 4+ Ce exists in the form of redox pairs;

[0062] And it was prepared by the following method:

[0063] Synthesis of S1, MgAl-LDH precursors

[0064] 1) First, take 0.2 mol magnesium nitrate hexahydrate (51.3 g) and 0.1 mol aluminum nitrate nonahydrate (37.5 g), dissolve them in 500 mL of deionized water, stir until completely dissolved, then add 0.6 mol urea (36.0 g), and stir again to dissolve.

[0065] 2) Transfer the mixed solution obtained in 1) to a 1 L three-necked flask, install a reflux condenser, heat to 95 °C in an oil bath under a nitrogen protective atmosphere, and stir under constant temperature reflux for 24 h at a stirring speed of 400 rpm. After the reaction is completed, allow it to cool naturally to room temperature.

[0066] 3) The product from 2) was vacuum filtered, the filter cake was washed three times with deionized water, placed in a petri dish, and dried in an oven at 80°C for 24 h. After drying, it was ground and passed through a 100-mesh standard sieve to obtain white MgAl-LDH powder with a yield of 32 g. It has a typical LDH layered structure and a Mg / Al molar ratio of 2.0:1.

[0067] S2, Co / Ce co-impregnation

[0068] 1) Preparation of impregnation solution: The saturated water absorption of this batch of MgAl-LDH powder was determined to be 1.2 mL / g. 30g of carrier was taken, and 36 mL of impregnation solution was required.

[0069] Weigh out 10.37 g of cobalt nitrate hexahydrate (containing 2.10 g of Co) and 6.20 g of cerium nitrate hexahydrate (containing 2.00 g of Ce). Dissolve both in 30 mL of deionized water and stir until completely dissolved. Add deionized water to make up to 36 mL. The calculated molar ratio of Co / Ce is 2.5:1.

[0070] 2) Equal-volume impregnation: Take 30.0 g of MgAl-LDH powder obtained from S1, spread it evenly in an enamel dish (30cm×20cm) with a thickness of 1cm, and use a dropping funnel to evenly add the impregnation solution from step 1) onto the LDH powder at a rate of 2 mL / min, while simultaneously stirring rapidly with a glass rod to ensure uniform distribution of the impregnation solution. After the addition is complete, continue stirring for 15 min. Allow to stand and age at room temperature for 4 h;

[0071] 3) Drying: Transfer the aged wet material from step 2) to a crucible, place it in a forced-air drying oven, and dry it at 70°C for 1.5 hours. After drying, remove it and allow it to cool naturally to room temperature.

[0072] S3, roasting

[0073] The dried sample was transferred to a porcelain boat and placed in a muffle furnace. The temperature was increased from room temperature to 150°C at a rate of 2°C / min and held for 1 hour. Then the temperature was increased to 350°C at a rate of 2°C / min and held for 2 hours. Finally, the temperature was increased to 550°C at a rate of 2°C / min and held for 4 hours. After calcination, the sample was allowed to cool naturally to room temperature.

[0074] The product obtained above is a gray-black powder, referred to as the catalyst precursor. The phase is a Co3O4 / CeO2 / Mg(Al)O composite oxide, and XRD confirmed that there is no NiAl2O4 spinel phase. Its specific surface area was determined to be 215 m² / g by the BET method, and its pore volume was determined to be 0.52 cm³ / g by the BJH method.

[0075] S4, Reduction and Activation

[0076] Take 5.0 g of the catalyst precursor obtained from S3, pack it into a fixed-bed reactor, introduce high-purity nitrogen gas at 50 mL / min, and raise the temperature to 400℃ at 5℃ / min.

[0077] Then switch to a reducing atmosphere of 10 vol% H2 and 90 vol% N2, reduce at 400℃ for 4 h, and after reduction, allow to cool naturally to 250℃ in the reducing atmosphere for later use.

[0078] The catalyst after reduction is in the active state, where Co exists as zero-valent nanoparticles and Ce exists as Ce₂O₃. 3+ Mainly.

[0079] Example 2

[0080] A rare earth coordination-based anti-poisoning self-healing catalyst differs from Example 1 in that only the amounts of cobalt nitrate hexahydrate and cerium nitrate hexahydrate are adjusted to make the Co / Ce molar ratio 1:1, while the other steps are exactly the same as in Example 1.

[0081] Example 3

[0082] A rare earth coordination-based anti-poisoning self-healing catalyst differs from Example 1 in that only the amounts of cobalt nitrate hexahydrate and cerium nitrate hexahydrate are adjusted to make the Co / Ce molar ratio 1:1.5, while the other steps are exactly the same as in Example 1.

[0083] Example 4

[0084] A rare earth coordination-based anti-poisoning self-healing catalyst differs from Example 1 in that only the amounts of cobalt nitrate hexahydrate and cerium nitrate hexahydrate are adjusted to make the Co / Ce molar ratio 1:2, while the other steps are exactly the same as in Example 1.

[0085] Example 5

[0086] A rare earth coordination-based anti-poisoning self-healing catalyst differs from Example 1 in that only the amounts of cobalt nitrate hexahydrate and cerium nitrate hexahydrate are adjusted to make the Co / Ce molar ratio 1:3, while the other steps are exactly the same as in Example 1.

[0087] Comparative Example 1

[0088] A catalyst, differing from that of Example 1, is prepared by the following method:

[0089] S1, Support: Take 30 g of γ-Al2O3 powder and calcine it at 500℃ for 4 h;

[0090] S2, Impregnation: Prepare a Co / Ce impregnation solution according to the same formula as S2 in Example 1, impregnate it onto γ-Al2O3 in equal volume, age and dry, and calcine at 550℃ for 4 h;

[0091] S3, Reduction and Activation: Same as S4 in Example 1, and the other steps are exactly the same as in Example 1.

[0092] Comparative Example 2

[0093] A catalyst, which differs from Example 1 in that Ce(NO3)3·6H2O is not added in S2, but Co is impregnated, the Co loading remains unchanged, and the other steps are exactly the same as in Example 1.

[0094] Comparative Example 3

[0095] A catalyst, which differs from Example 1 in that Ce(NO3)3·6H2O and Co(NO3)3·6H2O are not added in S2, and only deionized water is impregnated as a control, while the other steps are exactly the same as in Example 1.

[0096] Comparative Example 4

[0097] A catalyst, which differs from Example 1 in that Co(NO3)3·6H2O is not added in S2, only Ce is impregnated, the Ce loading remains unchanged, and the other steps are exactly the same as in Example 1.

[0098] Comparative Example 5

[0099] A catalyst, differing from that in Example 1, was used in which a commercially available NiO-MoO3 / γ-Al2O3 catalyst (NiO 5wt%, MoO3 15wt%) was reduced at 400°C in 10% H2 / N2 for 4 h.

[0100] The tests conducted according to the above experimental methods on Examples 1-5 and Comparative Examples 1-5 were as follows:

[0101] Example 1: With a Co / Ce molar ratio of 2.5:1, Co 6.2 wt%, and Ce 5.9 wt%, the initial deoxygenation rate was 96.2%. After 48 hours of poisoning with 500 ppm sulfur and 400 ppm nitrogen, the deoxygenation rate was 71.5%.

[0102] Fresh reduced Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [something] was as high as 76.2%, which dropped to 32.6% after poisoning and 74.1% after regeneration; the specific surface area was 215 m² / g and the pore volume was 0.52 cm³ / g.

[0103] Example 2: Co / Ce molar ratio = 1:1, Co 5.0 wt%, Ce 9.5 wt%, initial deoxygenation rate 92.4%, after 48 h of poisoning with 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate 68.2%;

[0104] Fresh reduced Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [something] was as high as 78.5%, which dropped to 35.1% after poisoning and 75.8% after regeneration; the specific surface area was 211 m² / g and the pore volume was 0.51 cm³ / g.

[0105] Example 3: With a Co / Ce molar ratio of 1:1.5, Co 4.2 wt%, and Ce 12.0 wt%, the initial deoxygenation rate was 89.6%. After 48 hours of poisoning with 500 ppm sulfur and 400 ppm nitrogen, the deoxygenation rate was 67.5%.

[0106] Fresh reduced Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [something] was as high as 80.2%, which dropped to 38.4% after poisoning and 77.2% after regeneration; the specific surface area was 208 m² / g and the pore volume was 0.50 cm³ / g.

[0107] Example 4: Co / Ce molar ratio = 1:2, Co 3.6 wt%, Ce 13.8 wt%, initial deoxygenation rate 86.3%, after 48 h of poisoning with 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate 66.1%;

[0108] Fresh reduced Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [unspecified substance] was as high as 81.5%, which dropped to 40.2% after poisoning and 78.5% after regeneration; the specific surface area was 205 m² / g and the pore volume was 0.49 cm³ / g.

[0109] Example 5: Co / Ce molar ratio = 1:3, Co 2.8 wt%, Ce 16.0 wt%, initial deoxygenation rate 80.5%, after 48 h of poisoning with 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate 63.8%;

[0110] Fresh reduced Ce³⁺Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [something] was as high as 83.6%, which dropped to 43.5% after poisoning and 79.8% after regeneration; the specific surface area was 202 m² / g and the pore volume was 0.48 cm³ / g.

[0111] Comparative Example 1, using γ-Al2O3 as the carrier, with the same Co / C ratio as Example 1, had an initial deoxygenation rate of 93.5%, and after 48 hours of poisoning with 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate was 52.8%.

[0112] Fresh reduced Ce³⁺Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [something] was as high as 73.5%, which dropped to 38.2% after poisoning and only 55.6% after regeneration; the specific surface area was 185 m² / g and the pore volume was 0.45 cm³ / g.

[0113] Comparative Example 2: Without Ce, only Co / LDH, with Co 6.2 wt%, its initial deoxygenation rate was 87.6%, and after 48 h of poisoning at 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate was 30.8%.

[0114] Because there is no Ce additive, the Ce³⁺ ratio cannot be determined, and the deoxygenation rate after regeneration is only 43.5%, which cannot be restored to the initial value; the specific surface area is 210 m² / g, and the pore volume is 0.51 cm³ / g.

[0115] Comparative Example 3: Blank carrier, without Co and Ce, with an initial deoxygenation rate of 8.2%, which basically has no corresponding effect and can be regarded as a blank group. After being poisoned by 500 ppm sulfur and 400 ppm nitrogen for 48 h, its deoxygenation rate was only 5.6%; specific surface area was 205 m² / g, and pore volume was 0.50 cm³ / g.

[0116] Comparative Example 4: No Co, only Ce / LDH, Ce 6.0 wt%, its initial deoxygenation rate was 4.8%, and after 48 h of poisoning at 500 ppm sulfur and 400 ppm nitrogen, its deoxygenation rate was 3.5%;

[0117] Fresh reduced Ce³⁺Ce 3+ / (Ce 3+ and Ce 4+ The proportion of [unclear] was as high as 81.2%, only 42.5% after poisoning, and 76.8% after regeneration; the specific surface area was 208 m² / g, and the pore volume was 0.49 cm³ / g.

[0118] Comparative Example 5: A commercial Ni-Mo / γ-Al2O3 catalyst with an initial deoxygenation rate of 96.8% reduced to 28.4% after 48 hours of poisoning with 500 ppm sulfur and 400 ppm nitrogen.

[0119] Because there is no Ce additive, the Ce³⁺ ratio cannot be determined, and in-situ regeneration is not possible; specific surface area is 176 m² / g, pore volume is 0.41 cm³ / g; NiO is 5.2 wt%, MoO is 14.8 wt%.

[0120] It should also be noted that, due to limitations in experimental costs, patent priority time limits, and the general understanding of parameter response patterns among those skilled in the art, this specification only uses Examples 1-5 and Comparative Examples 1-5 as representatives for detailed experimental verification. However, based on the formation mechanism fully disclosed in this specification, those skilled in the art can reasonably expect to obtain excellent results within a small range.

[0121] Performance Testing Test II

[0122] The reduced catalysts from Examples 1-5 and Comparative Examples 1-5 were used in a fixed-bed reactor for the hydrodeoxygenation of waste oils. The reaction conditions were uniformly set as follows: temperature 280°C, hydrogen pressure 4 MPa, hydrogen-to-oil volume ratio 800:1, and mass hourly space velocity 1.0 h⁻¹. -1 ;

[0123] The raw material was kitchen waste oil with an initial sulfur content of 120 ppm and a nitrogen content of 85 ppm. After continuous operation for 100 hours, samples were taken every 12 hours to measure the deoxygenation rate, and the average of the last 5 measurements was taken as the "initial deoxygenation rate". Then, thiophene and pyridine were added to the raw oil to increase the sulfur content to 500 ppm and the nitrogen content to 400 ppm. The operation was continued for 48 hours, and the "deoxygenation rate after poisoning" was measured. The results are shown in Table 1.

[0124] Table 1: Comparison of initial activity and anti-poisoning properties

[0125]

[0126] As can be seen from Table 1 above, the initial deoxygenation rates of Examples 1-5 were 80.5-96.2%, and the decrease in deoxygenation rate after poisoning was 16.7-24.7%, which was significantly better than the comparison ratios. The specific analysis is as follows:

[0127] 1) Ce 3+ It plays a sacrificial protective role: Comparing Example 1 with Comparative Example 2 without Ce, it can be seen that both use LDH as a carrier and have similar Co content, but the deoxygenation rate of Example 1 after poisoning decreased by only 24.7%, while that of Comparative Example 2 decreased by as much as 56.8%;

[0128] This directly proves that when the reactants contain sulfur and nitrogen impurities, Ce... 3+ It preferentially coordinates with the toxic substance to form Ce-S / Ce-N compounds, and is itself oxidized to Ce. 4+ This protects the main active metal Co. 0 Avoid direct poisoning; without Ce, the poison directly attacks Co. 0 This leads to a sharp decrease in activity, as can be seen in the blank carrier comparative example 3 and the Co-free comparative example 4, which have almost no deoxygenation activity.

[0129] 2) The LDH carrier plays a synergistic role in preventing poisoning: Comparing Example 1 and Comparative Example 1, it can be seen that both contain Co-Ce and have similar molar ratios, but the carriers are different. In Example 1, the deoxygenation rate after poisoning was as high as 71.5%, with a decrease of only 24.7%; while in Comparative Example 1, the deoxygenation rate after poisoning was only 52.8%.

[0130] This indicates that LDH-derived Mg(Al)O composite oxides possess abundant basic sites, enabling them to adsorb and neutralize acidic poisons, while their unique lamellar structure provides Ce 3+ Provides a confined environment, enhancing Ce3+ The coordination efficiency with toxins is important; if LDH is lacking, even with Ce, the ability to resist poisoning will decrease.

[0131] 3) The Co / Ce molar ratio exhibits a criticality: As can be seen from Examples 1 to 5, as the Co / Ce molar ratio decreases, the initial deoxygenation rate gradually decreases due to the dilution of Co active sites by Ce, but the rate increases further due to the increased Ce content. 3+ The rate of decrease in deoxygenation rate after poisoning by toxic substances can be captured and gradually reduced;

[0132] Example 1 shows that it can maintain a high initial deoxygenation rate while having good anti-poisoning ability, which is the preferred ratio of this application. If there is too much Ce, see Example 5, which results in a large loss of initial activity; if there is insufficient Ce, see Comparative Example 2, which results in a sharp deterioration of anti-poisoning performance. Therefore, this application limits the Co / Ce molar ratio to 1.5-2.5:1, which is the best window for this balance.

[0133] 4) Compared with Comparative Example 5, which uses a commercial Ni-Mo / γ-Al2O3 catalyst, it can be seen that although the initial deoxygenation rate of Comparative Example 5 is as high as 96.8%, it drops sharply to 28.4% after poisoning. This is because of the lack of Ce. 3+ The sacrificial protection mechanism involves the poison directly attacking the Ni and Mo active sites, forming irreversible sulfides, unlike the method used in this application which relies on Ce. 3+ Its priority coordination capability lays the foundation for subsequent in-situ self-repair.

[0134] Performance Testing Test III - In-situ Self-Healing Cyclic Performance

[0135] The catalyst poisoned by sulfur and nitrogen under high load for 48 hours was subjected to in-situ regeneration treatment:

[0136] 1) Stop the oil supply, introduce 0.5 vol% O2 / N2 mixed gas at 50 mL / min, raise the temperature to 350℃ at 2℃ / min, and keep the temperature constant for 2 hours; then switch back to 10 vol% H2 / N2 mixed gas and reduce at 400℃ for 2 hours.

[0137] 2) After regeneration, feedstock oil with 120 ppm sulfur and 85 ppm nitrogen was introduced again and run under the same conditions for 48 hours. The deoxygenation rate after regeneration was measured. The "poisoning-regeneration" cycle was repeated 5 times and the deoxygenation rate after each regeneration was recorded. The test results are shown in Table 2.

[0138] Table 2: In-situ self-healing circulation performance (deoxygenation rate, %)

[0139]

[0140] Note: Comparative Examples 2 and 5 could not achieve self-repair under the mild regeneration conditions described in this invention. The values ​​in the table represent a slight rebound after only burning off carbon deposits, not Ce. 3+ / Ce 4+ This is due to the cycle.

[0141] As can be seen from the table above, after 5 cycles of "poisoning-regeneration", the regeneration deoxygenation rate of Example 1 of this application can still reach 83.5%, recovering to 86.8% of the fresh state. In contrast, the regeneration recovery rate of Comparative Example 1 is only 45.8%, while Comparative Examples 2 and 5 are almost unable to regenerate. The specific analysis is as follows:

[0142] 1) Ce 3+ / Ce 4+ The redox cycle is reversible: In Example 1, after 5 cycles, the regeneration deoxygenation rate still reached 83.5%, recovering to 86.8% of the fresh state, which directly proves that Ce 3+ / Ce 4+ Reversibility of redox pairs, Ce poisoning stage 3+ Oxidized to Ce 4+ And capture the poison, regeneration stage Ce 4+ Reduced to Ce 3+ It releases toxins, and the reversible cycle is the fundamental basis of the "self-repair" function of this application. Comparative Examples 2 and 5 do not have this cycle, so they cannot achieve effective regeneration.

[0143] 2) The LDH memory effect plays a key role in multiple regenerations: Comparative Example 1 recovered to only 68.5% after the first regeneration and only 42.6% after the fifth regeneration, which is much lower than Example 1. The reason for this is that the Mg(Al)O composite oxide formed by the LDH support after calcination retains the memory effect of the layered structure.

[0144] During oxygen-containing regeneration, Mg(Al)O can be partially reconstructed into an LDH layered structure, accompanied by the reinsertion of lattice water and hydroxyl groups. This process induces Ce species redispersion and prevents Ce from being dispersed. 3+ In multiple redox cycles, Ce aggregates and becomes inactive, while γ-Al2O3 does not have this memory effect. Ce gradually aggregates, leading to a gradual decline in regeneration capacity. It is evident that the LDH carrier is the core for achieving multiple efficient in-situ self-repair.

[0145] 3) Ce-free systems cannot self-repair: Comparative Example 2 only recovered from 30.8% to 34.2% after the first regeneration, and only 29.1% after the fifth regeneration, showing almost no recovery. This is because Ce was absent. 3+ / Ce 4+ Redox pairs, poisons directly attack Co 0The formation of irreversible Co-S / Co-N species, which cannot be recovered by conventional reduction, proves that Ce's reversible sacrifice mechanism is the core of the self-repair function of this application.

[0146] 4) Commercial catalysts cannot be regenerated in situ: Under the mild oxygen-containing regeneration conditions of this application, the deoxygenation rate of Comparative Example 5 only increased slightly from 28.4% to 30.5%, with almost no recovery. Traditional Ni-Mo catalysts need to be shut down and unloaded before they can be calcined in air at temperatures above 500°C for regeneration. Moreover, the activity is severely lost irreversibly after multiple regenerations. This highlights the advantage of the catalyst in this application in achieving in-situ self-repair under mild conditions.

[0147] Performance testing test IV-XPS analysis of Ce valence state changes

[0148] XPS analysis was performed on samples of the catalyst from Example 1 in the fresh reduced state, after the first poisoning, and after the first regeneration, and Ce was calculated. 3+ / (Ce 3+ and Ce 4+ The proportions are shown in Table 3.

[0149] Table 3: Ce in Example 1 3+ / (Ce 3+ and Ce 4+ Changes in proportion

[0150]

[0151] As can be seen from the table above, Ce 3+ / (Ce 3+ and Ce 4+ The proportion was as high as 76.2% in the fresh reduced state, dropped sharply to 32.6% after poisoning, and recovered to 74.1% after regeneration, perfectly demonstrating the reversible change pattern of "high-low-high". The specific analysis is as follows:

[0152] 1) Fresh reduced state: Ce 3+ / (Ce 3+ and Ce 4+ The proportion was as high as 76.2%, indicating that Ce was mainly converted into Ce after reduction and activation. 3+ It exists in form, with a high proportion of Ce. 3+ This means that abundant unpaired electrons and empty orbitals make it easy for the catalyst to coordinate with sulfur and nitrogen atoms, which is a prerequisite for the catalyst to have sacrificial protection capabilities.

[0153] 2) After poisoning: Ce 3+ The proportion plummeted to 32.6%, with a large amount of Ce 3+ Oxidized to Ce 4+ And it forms Ce-S / Ce-N complexes, which directly proves that in sulfur- and nitrogen-containing feedstocks, Ce... 3+Indeed, it preferentially coordinates with the toxicant, capturing the toxicant by increasing its own valence state, thereby protecting Co. 0 The active site, it is this change in valence state that allows the deoxygenation rate to be maintained after poisoning, instead of collapsing directly like the Ce-free system;

[0154] 3) After regeneration: Ce 3+ The proportion rebounded to 74.1%, close to the fresh state level, indicating that during the oxygen-containing regeneration phase, Ce... 4+ Successfully restored to Ce 3+ Simultaneously, the toxin is desorbed. This process is made possible by the strong electronic cooperation between Co and Ce, which reduces the Ce content. 4+ The energy barrier for reduction; and the memory effect of the LDH carrier induces Ce species redispersibility during regeneration, preventing Ce from being dispersed. 3+ Reunion.

[0155] Performance testing and comparison of long-term operating life of V-catalysts

[0156] Example 1 and Comparative Example 5 were respectively loaded into fixed beds and continuously operated in actual waste oil containing 120 ppm sulfur and 85 ppm nitrogen. The time required for the deoxygenation rate to decrease from the initial value to 80% was recorded.

[0157] Then, in-situ regeneration was performed every 200 hours for Example 1 (under the conditions of Experiment III), and the total stable operating time with the deoxygenation rate maintained above 80% was recorded. The relevant test results are shown in Table 4.

[0158] Table 4: Comparison of Catalyst Lifetime

[0159]

[0160] As can be seen from the table above, the single-pass lifespan of the catalyst in Example 1 of this application is 256 h, which is 2.37 times that of the catalyst in Comparative Example 5; after in-situ regeneration, the total lifespan can reach 1520 h, which is more than 14 times that of Comparative Example 5. The specific reasons are analyzed as follows:

[0161] 1) Improved single-trip lifespan: The single-trip T80 of Example 1 is 256 h, which is 2.37 times that of Comparative Example 5 (108 h). This is because Ce 3+ The sacrifice protection mechanism delayed Co 0 The poisoning rate allows the catalyst to maintain high activity for a longer time under the same poison concentration.

[0162] 2) Leap in total lifespan brought about by in-situ regeneration: In Example 1, through in-situ regeneration every 200 hours, the deoxygenation rate was restored to more than 92% after each regeneration, and the total stable operating time reached 1520 hours.

[0163] In contrast, Comparative Example 5 could not be regenerated in situ under the mild conditions of this invention. Each time the activity decreased, it could only be shut down, the agent removed, and calcined at high temperature, resulting in extremely high industrial costs.

[0164] The above are all modifications that can be made to this embodiment without contributing any inventive step, or solutions that clearly constitute technical teaching, after reading this specification. However, as long as they are within the scope of the claims of this application, they should be protected by patent law.

Claims

1. A rare earth coordination-based anti-poisoning self-healing catalyst, characterized in that, The Co-Ce bimetallic system supported on layered bimetallic hydroxide-derived composite oxides comprises the following components: Support: The support is a Mg(Al)O composite oxide obtained by calcination of MgAl-LDH; Main active metal: The main active metal is Co, which exists in a zero-valence state and in nanoparticle form; Additives: The additives are Ce 3+ Ce 4+ Ce exists in the form of redox pairs.

2. The anti-poisoning self-healing catalyst based on rare earth coordination according to claim 1, characterized in that, The molar ratio of the main active metal Co to the auxiliary agent Ce is (1.5-2.5):1; The amount of the main active metal Co is 6-10 wt% of the total mass of the catalyst. The amount of additive Ce is 3-6 wt% of the total mass of the catalyst.

3. The anti-poisoning self-healing catalyst based on rare earth coordination according to claim 1, characterized in that, The specific surface area of ​​the Mg(Al)O composite oxide is 180-250 m². 2 / g; The pore volume is 0.4-0.7 cm. 3 / g.

4. The anti-poisoning self-healing catalyst based on rare earth coordination according to claim 1, characterized in that, The molar ratio of Mg to Al in the Mg(Al)O composite oxide is (2-3):

1.

5. A method for preparing the anti-poisoning self-healing catalyst based on rare earth coordination as described in any one of claims 1-4, characterized in that, Includes the following steps: Synthesis of S1 and MgAl-LDH precursors: Magnesium salts and aluminum salts were dissolved in water at the corresponding molar ratio using the urea hydrothermal coprecipitation method. Urea was added, and the mixture was refluxed and stirred at 90-100℃ for 20-30 h to obtain MgAl-LDH powder. S2, Co / Ce co-impregnation: Cobalt salt and cerium salt are dissolved in water in the corresponding molar ratio, and the impregnation solution is added dropwise to the MgAl-LDH powder obtained in S1 using the equal volume impregnation method. The powder is then aged and dried. S3, calcination: The product after drying S2 is calcined in sections in air at 500-600℃ for 3-5 h to obtain Co3O4 / CeO2 / Mg(Al)O composite oxide; S4. Reduction and Activation: The Co3O4 / CeO2 / Mg(Al)O composite oxide obtained in S3 is reduced in a hydrogen-containing atmosphere at 350-450℃ for 3-5 h to obtain the active catalyst Co. 0 / Ce2O3 / Mg(Al)O.

6. The preparation method of the anti-poisoning self-healing catalyst based on rare earth coordination according to claim 5, characterized in that, The specific process parameters are as follows: The total molar ratio of urea to magnesium salt and aluminum salt in S1 is (2-4):1, the reflux stirring temperature is 95℃, and the reaction time is 24 h. The heating rate of the roasting in S3 is 1-3℃ / min, and the specific segmented roasting process is as follows: hold at 350℃ for 1-3h, and hold at 550℃ for 3-5h.

7. The preparation method of the anti-poisoning self-healing catalyst based on rare earth coordination according to claim 5, characterized in that, The cobalt salt in S2 is Co(NO3)2·6H2O, and the cerium salt is Ce(NO3)3·6H2O; the aging time after impregnation is 3-5 h, and the drying procedure is: 50-90℃, 1-2 h.

8. A method for preparing bio-jet fuel by hydrodeoxygenation of waste oil using the catalyst according to any one of claims 1-4, characterized in that, Includes the following steps: The reduced and activated catalyst was loaded into a fixed-bed reactor, hydrogen gas was introduced, and the temperature was raised to the reaction temperature of 250-300℃, the hydrogen pressure was 3-5 MPa, and the space velocity was 0.5-2.0 h⁻¹. -1 Waste oil is pumped into a reactor for hydrodeoxygenation to obtain C. 15-C18 Alkane products; The method also includes a self-repairing regeneration step for the catalyst: when the deoxygenation rate is detected to drop below 70% of the initial value, the oil feed is stopped, an oxygen-containing regeneration atmosphere is introduced, and the catalyst is treated at 300-400℃ for 1-4 hours. Then, the catalyst is switched back to a reducing atmosphere and reduced at 350-450℃ for 1-3 hours, thus completing the in-situ regeneration.

9. The method for preparing bio-jet fuel by hydrodeoxygenation of waste oil according to claim 8, characterized in that, The oxygen-containing regeneration atmosphere is a N2 mixture containing 0.1-1 vol% O2, with the balance being N2; The reducing atmosphere is a N2 mixture containing 5-15 vol% H2, with the balance being N2.

10. The application of a self-healing, anti-poisoning hydrodeoxygenation catalyst in the preparation of bio-jet fuel, characterized in that, The product is obtained using the catalyst according to any one of claims 1-4 or the preparation method according to any one of claims 5-7, or using the method according to any one of claims 8-9.

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