Hydrodeoxygenation and denitrogenation catalyst, and preparation method and application thereof
Patent Information
- Application Number
- CN202611139360.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-29
- Publication Date
- 2026-10-13
AI Technical Summary
[0003]为了解决上述问题，已有技术尝试采用两级固定床或引入保护剂的方式，但仍无法适应酸值高于20mgKOH/g、磷含量高于50mg/kg的低品质废弃油脂
[0025]1.外层捕集层主动捕获磷、金属杂质；氢溢流促进组分实现积碳原位氢解；酸碱协同位点避免强酸中毒。三者协同使催化剂单程寿命≥2500小时，是常规催化剂的1.7倍以上。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrodeoxygenation and denitrogenation catalyst technology, specifically relating to a hydrodeoxygenation and denitrogenation catalyst, its preparation method, and its application. Background Technology
[0002] With the rapid development of sustainable aviation fuel and biodiesel industries, waste animal and vegetable oils, such as waste cooking oil, non-edible vegetable oils, and animal fats, have become one of the most important low-carbon raw materials. However, due to the complex sources of waste oils, they often contain high levels of free fatty acids, with acid values reaching over 50 mg KOH / g; phosphorus content in phospholipids exceeding 50 mg / kg, and even exceeding 100 mg / kg; metal ions such as Ca, Mg, Fe, and Na; nitrogen-containing compounds; and impurities such as colloids. Existing commercial hydrodeoxygenation catalysts, such as Ni-Mo / Al2O3 and Co-Mo / Al2O3, require high purity raw materials and must undergo deep pretreatment such as degumming, deacidification, and demetallization. Otherwise, the catalyst will deactivate in a short period of time due to carbon buildup, poisoning, or pore blockage.
[0003] To address these issues, existing technologies have attempted to employ two-stage fixed beds or introduce protective agents, but these methods still cannot adapt to low-quality waste oils with acid values exceeding 20 mg KOH / g and phosphorus content exceeding 50 mg / kg. Suspended-bed hydrogenation technology can handle relatively dirty feedstocks, but suspended-bed catalysts are generally for single-use, and using a suspended bed alone is insufficient to obtain high-quality jet fuel. Therefore, developing a pretreatment catalyst that combines broad feedstock adaptability with long-term stability has significant industrial application value. Summary of the Invention
[0004] To address the technical problems mentioned in the background art, the present invention provides a hydrodeoxygenation and denitrogenation catalyst, its preparation method, and its application. The technical solution adopted is as follows:
[0005] A hydrodeoxygenation and denitrogenation catalyst, characterized in that the catalyst has a layered structure: an outer layer is an impurity trapping layer with a thickness of 5~50μm, and an inner layer is a hydrodeoxygenation and denitrogenation active layer.
[0006] The outer impurity trapping layer contains one or more of amorphous silica-alumina, aluminum phosphate, iron oxide, and zinc oxide, accounting for 5% to 15% of the total catalyst mass. It has a strong chemical adsorption capacity for impurities such as phosphorus and metal ions in the raw materials, preferentially reacts with the impurities, consumes itself, and protects the inner active sites.
[0007] The inner hydrogenation, deoxygenation, and denitrification active layer, by weight percentage, comprises: 5-20% nickel oxide and 10-30% molybdenum oxide, or 3-15% cobalt oxide and 10-25% molybdenum oxide;
[0008] Hydrogen overflow promoting component: selected from one or more of Pt and Pd, with a content of 0.01~0.5%, and a content of 1~10% based on metal content;
[0009] Additives: Phosphorus 0.5-5%, Boron 0.1-3%, and Rare Earth Ce 0.1-2%;
[0010] Composite carrier: The composite carrier is composed of molecular sieves with mesoporous-microporous composite pore structure accounting for 50-80% by mass and mesoporous oxide accounting for 20-50% by mass, and the composite carrier contains nitrogen-doped weak base sites on the surface, with the nitrogen doping amount being 0.1-2.0% by mass.
[0011] The catalyst preparation method includes the following steps:
[0012] Step 1: Preparation of the composite support
[0013] S11: The molecular sieve raw powder is treated in 0.2~1.0mol / L HCl solution at 40~80℃ for 0.5~4h, washed and dried to obtain modified molecular sieve;
[0014] S12: Al2O3-TiO2 composite oxides were prepared by template method to synthesize SBA-15 and MCM-41 or by coprecipitation method;
[0015] S13: The modified molecular sieve is mixed with mesoporous oxide, dilute nitric acid and kneading aid are added and extruded into strips with a diameter of 1.5~4.0 mm. The strips are dried at 100~120℃ for 6~12 h and calcined at 500~600℃ for 4~6 h to obtain the composite carrier precursor.
[0016] S14: Nitrogen doping: The composite support precursor is immersed in an organic precursor solution containing melamine, urea and ethylenediamine, dried and then pyrolyzed at 400~600℃ for 1~3h under an inert atmosphere to obtain a nitrogen-doped composite support.
[0017] Step 2: Sequential impregnation method, layered structure construction
[0018] S21: Outer trapping layer impregnation: Prepare a precursor solution containing Al, Si, P, Fe and Zn trapping components, and impregnate the composite carrier particles using an equal volume impregnation method. After impregnation, dry at 100~120℃ for 2~4h and calcine at 300~400℃ for 2~3h to form a 5~50μm trapping shell layer on the outer surface of the particles.
[0019] S22: Inner layer active component impregnation: Prepare a co-impregnation solution containing active components Ni, Mo, Co, Pt, P, B, Ce and additives, pH 8~10, and impregnate the carrier with the above-mentioned trapping layer again with an equal volume. The active solution enters the interior of the particles by capillary action, while the outer trapping layer has been pre-cured. The active components are mainly deposited in the inner layer. After impregnation, dry at 100~120℃ for 4~12h and calcine at 400~600℃ for 3~6h to obtain the catalyst precursor.
[0020] S23: For catalysts containing Pt and Pd, activation is achieved by reduction at 350~450℃ for 2~6h under a hydrogen atmosphere.
[0021] A combined process for the hydrodeoxygenation and denitrogenation of waste animal and vegetable oils using the above-mentioned catalyst includes:
[0022] (1) Suspended bed pretreatment section: Waste oil raw materials are mixed with Ni-Mo / Al2O3 powder catalyst with a particle size of 50~300μm and fed into a suspended bed reactor. The reaction is carried out at a temperature of 300~380℃, a pressure of 6~12MPa, and a hydrogen-to-oil ratio of 500~1500Nm. 3 / m 3 Liquid hourly space velocity (LISH) 0.5~2.0 h⁻¹ -1 Under the conditions of pre-hydrogenation reaction;
[0023] (2) After gas-liquid separation, the product from the pretreatment section enters the liquid phase into a fixed-bed reactor, which is loaded with the catalyst described in this invention; the reaction conditions are: temperature 320~420℃, pressure 6~12MPa, hydrogen-to-oil ratio 800~2000Nm. 3 / m 3 Liquid hourly space velocity (LISH) 0.5~1.5 h⁻¹ -1 During this reaction phase, the catalyst utilizes hydrogen overflow to promote the overflow of hydrogen atoms generated by the components, which then undergo hydrogenolysis with the carbon deposition precursor to achieve in-situ self-regeneration, maintaining the surface carbon area at ≤5wt%.
[0024] Compared with the prior art, the present invention has the following beneficial effects:
[0025] 1. The outer trapping layer actively captures phosphorus and metallic impurities; hydrogen overflow promotes in-situ hydrogenolysis of carbon deposits; and acid-base synergistic sites prevent strong acid poisoning. The synergy of these three factors results in a catalyst single-pass lifetime of ≥2500 hours, which is more than 1.7 times that of conventional catalysts.
[0026] 2. It can directly process low-quality waste oil with acid value ≤60mgKOH / g, phosphorus content ≤120mg / kg, and metal ion content ≤200mg / kg, significantly reducing raw material costs.
[0027] 3. Deoxygenation rate ≥99%, denitrification rate ≥98%, liquid product yield ≥90%, aviation kerosene fraction yield ≥43%, product freezing point ≤-47℃, meeting international aviation kerosene standards.
[0028] 4. Eliminates traditional steps such as degumming, deacidification, and water washing in raw material pretreatment; extends catalyst life, reducing replacement frequency and downtime losses; reduces overall costs by 20% to 30%.
[0029] 5. It does not use toxic solvents, uses extremely low amounts of precious metals (as low as 0.01 wt%), and can be regenerated multiple times. Detailed Implementation
[0030] Example 1
[0031] Preparation of Catalyst Cat-1:
[0032] Preparation of composite carriers
[0033] Take 100g of ZSM-22 molecular sieve with a silica-to-alumina ratio of 60, treat it with 0.4mol / L NaOH solution at 70℃ for 2h, filter and wash until neutral, and dry to obtain alkali-treated modified ZSM-22;
[0034] The modified ZSM-22, 60g and 40g, has a specific surface area of 650m². 2 / g, pore volume 0.85cm 3 / g of SBA-15 mesoporous molecular sieve was mixed, and dilute nitric acid and citric acid were added and kneaded. The mixture was then extruded into 2.0mm clover strips, dried at 120℃ for 6h, and calcined at 550℃ for 5h to obtain the composite carrier precursor.
[0035] Nitrogen doping
[0036] The above-mentioned composite carrier precursor was immersed in a 5wt% melamine aqueous solution and soaked at room temperature for 2 hours. It was then removed and dried at 120°C, and then pyrolyzed at 500°C for 2 hours under N2 atmosphere to obtain a nitrogen-doped composite carrier with an N content of 0.8wt%.
[0037] Outer trapping layer sedimentation
[0038] Preparation of the trapping layer impregnation solution: Dissolve 20g Al(NO3)3·9H2O, 10g tetraethyl orthosilicate, and 5g Fe(NO3)3·9H2O in 100mL of ethanol / water mixture, add 3mL of concentrated nitric acid, and impregnate the above solution onto 100g of nitrogen-doped composite support using the equal volume impregnation method. Dry at 120℃ for 2h and calcine at 350℃ for 2h to form an Fe-ASA trapping layer of about 15μm thickness on the particle surface, with an Fe content of 2wt%.
[0039] Inner layer active component impregnation
[0040] Preparation of the active component impregnation solution: 33.3 g nickel nitrate, 22.1 g ammonium molybdate, 4.5 g 85% phosphoric acid, 2.2 g boric acid, 5.2 g cerium nitrate, and 0.05 g chloroplatinic acid (Pt content approximately 0.02 wt%) were dissolved in 80 mL deionized water, and the pH was adjusted to 9.0 with ammonia. The impregnation solution was sprayed onto a support with a pre-existing trapping layer using an equal-volume impregnation method. After standing for 2 h, the solution was dried at 120 °C for 8 h and calcined at 500 °C for 4 h to obtain catalyst Cat-1. ICP analysis showed that Cat-1 contained 12.3% NiO, 18.0% MoO3, 1.7% P2O5, 0.6% B2O3, 1.5% CeO2, 0.02% Pt, and 1.8% Fe. The outer trapping layer thickness was approximately 12–18 μm.
[0041] Evaluation of combined processes
[0042] The raw material is waste cooking oil with an acid value of 48 mg KOH / g, phosphorus content of 102 mg / kg, total metal ion content of 190 mg / kg, and nitrogen content of 0.16 wt%. The suspended bed pretreatment section uses Ni-Mo / Al2O3 powder catalyst, and the reaction conditions are: 350℃, 8 MPa, and a hydrogen-to-oil ratio of 1100 Nm³. 3 / m 3 LHSV=1.0h -1 Fixed bed section: 100 mL Cat-1 catalyst was loaded. Reaction conditions: 370℃, 8 MPa, hydrogen-to-oil ratio 1300 Nm. 3 / m 3 LHSV=0.8h -1 After 2800 hours of continuous operation, an automatic shutdown inspection was conducted: deoxygenation rate 99.3%, denitrification rate 98.6%, liquid product yield 91.2%, jet fuel fraction yield 44.0%, jet fuel freezing point -48.7℃. Catalyst carbon deposition was 4.2wt%, specific surface area retention was 79%, and activity decrease rate was <8%. Impurities such as phosphorus, iron, and calcium were enriched in the trapping layer, and the inner active metal layer showed no obvious sintering.
[0043] Example 2: Co-Mo system, MoP hydrogen overflow
[0044] Catalyst Cat-2 preparation: The composite support is acid-treated SAPO-11 + MCM-41 with a mass ratio of 7:3 and nitrogen doping of 0.6wt%; the trapping layer is aluminum phosphate; the active component impregnation solution contains 25.8g cobalt nitrate, 24.7g ammonium molybdate, and 3.8g phosphoric acid, with ammonium hydrogen phosphate added to adjust the P / Mo molar ratio to 1.2. After reduction with H2 at 500℃, MoP is generated as a hydrogen overflow promoting component.
[0045] Evaluation of raw materials: Mixed animal fat / waste cooking oil, oleic acid value 42 mg KOH / g, phosphorus 81 mg / kg, metals 153 mg / kg. After 2600 hours of operation: deoxygenation rate 98.9%, denitrification rate 92.1%, liquid yield 90.0%, jet fuel yield 42.3%, carbon deposits 4.8%.
[0046] Example 3: Low-cost non-precious metal solution
[0047] Catalyst Cat-3 preparation: The support was ZSM-5 + Al2O3-TiO2 (mass ratio 6:4), with nitrogen doping of 0.5 wt%; the trapping layer was ZnO + SiO2, and the active layer was Ni-Mo-PB, with the addition ratios the same as in Example 1. Raw material evaluation: High-acid-value waste cooking oil with an acid value of 58 mg KOH / g, phosphorus of 115 mg / kg, and metal content of 208 mg / kg. After 2200 hours of operation: Deoxygenation rate 98.2%, denitrification rate 90.5%, liquid yield 88.5%, jet fuel yield 41.0%, and carbon deposition 5.9%.
[0048] Example 4: No outer trapping layer
[0049] Catalyst Cat-4: Except for the absence of an outer trapping layer deposition, it is identical to that of Example 1. Under the same raw materials and processes, after 1800 hours of operation, the deoxidation rate dropped below 93%. A shutdown inspection revealed 7.8% carbon buildup, 0.3 wt% phosphorus deposition on the inner active metal surface, and a specific surface area retention rate of 68%. This indicates that without a trapping layer, the lifespan is shortened by approximately 35%.
[0050] Example 5 Hydrogen-free overflow promoting component
[0051] Catalyst Cat-5: Except for the absence of Pt, it is identical to that of Example 1. After 2000 hours of operation, the deoxygenation rate was 94.2%, carbon deposition was 6.8%, and the specific surface area retention rate was 71%. This is significantly different from Example 1, indicating that the hydrogen overflow self-regeneration mechanism is crucial for the ultra-long lifespan.
[0052] Example 6: Nitrogen-free
[0053] Catalyst Cat-6: Except for the absence of nitrogen doping, it is identical to that in Example 1. With the same raw materials, the denitrification rate is only 88.5%, decreasing to 83% after 2200 hours of operation. This indicates that nitrogen-doped weak base sites significantly promote the reversible adsorption and removal of nitrogen-containing compounds.
[0054] Comparative Example 1: Commercial catalyst, without slurry bed pretreatment
[0055] A commercially available Ni-Mo / γ-Al2O3 hydrodeoxygenation catalyst with 14% NiO and 19% MoO3 was used in a single-stage fixed bed, with the same raw materials as in Example 1. After 450 hours of operation, the deoxygenation rate was <90%, and after 600 hours of shutdown, 21% carbon buildup was observed, indicating severe catalyst poisoning.
[0056] Comparative Example 2: Catalyst Cat-1 of the present invention, but without slurry bed pretreatment.
[0057] Comparative Example 2: Catalyst Cat-1, but the suspended bed section was omitted, and the feedstock went directly into the fixed bed. After 1400 hours of operation, the deoxygenation rate was <92%, and the carbon buildup during shutdown was 10.2%.
[0058] Summary of the effects of the examples
[0059]
[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A hydrodeoxygenation and denitrogenation catalyst, characterized in that, The catalyst has a layered structure, with an outer impurity trapping layer and an inner active layer for hydroaddition, deoxygenation, and denitrogenation. The outer layer is an impurity trapping layer with a thickness of 5~50μm, the trapping layer accounts for 5%~15% of the total mass, and the trapping layer contains one or more trapping components selected from amorphous aluminum silica, aluminum phosphate, iron oxide, and zinc oxide; The inner layer is a hydrodeoxygenation and denitrogenation active layer, which contains a Ni-Mo bimetallic active component, wherein nickel oxide accounts for 5-20% of the total mass and molybdenum oxide accounts for 10-30% of the total mass, or cobalt oxide accounts for 3-15% of the total mass and molybdenum oxide accounts for 10-25% of the total mass; The composite carrier is composed of 50-80% modified molecular sieve and 20-50% mesoporous oxide by mass. The composite carrier contains nitrogen-doped weak base sites on the surface, with the nitrogen doping amount being 0.1~2.0% of the total mass.
2. The hydrodeoxygenation and denitrogenation catalyst as described in claim 1, characterized in that, The molecular screening is based on at least one of ZSM-22, SAPO-11, and ZSM-5 after acid treatment; The mesoporous oxide is selected from at least one of SBA-15, MCM-41, and Al2O3-TiO2 composite oxides; The specific surface area of the composite carrier is 200~500m². 2 / g, pore volume 0.4~1.0cm 3 / g, with an average pore size of 5~20nm.
3. The hydrodeoxygenation and denitrogenation catalyst according to claim 1, characterized in that, The active layer also includes an auxiliary agent selected from one or more of P, B, and Ce.
4. The hydrodeoxygenation and denitrogenation catalyst as described in claim 3, characterized in that, The active layer also contains additives, of which: phosphorus accounts for 0.5-5% of the total mass, boron accounts for 0.1-3% of the total mass, and rare earth Ce accounts for 0.1-2% of the total mass.
5. The hydrodeoxygenation and denitrogenation catalyst as described in claim 1, characterized in that, It also includes a hydrogen overflow promoting component, which is selected from one or more of Pt and Pd, accounting for 0.01 to 0.5% of the total mass.
6. A method for preparing a hydrodeoxygenation and denitrogenation catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: (a) Preparation of a composite support and nitrogen doping treatment; (b) The trapping layer components are impregnated or sprayed onto the surface of the composite carrier, and then dried and calcined to form the outer trapping layer; (c) Impregnate the product obtained in step (b) with an impregnation solution containing active metal and hydrogen overflow promoting components, so that the active components are mainly loaded in the inner layer, and then dry and calcinate to obtain the catalyst.
7. The method for preparing the hydrodeoxygenation and denitrogenation catalyst according to claim 6, characterized in that, The nitrogen doping treatment involves immersing the composite carrier in a nitrogen-containing organic precursor solution and then pyrolyzing it at 400-600°C under an inert atmosphere. The nitrogen-containing organic precursor is selected from one or more of melamine, urea, and ethylenediamine.
8. A production process using the hydrodeoxygenation and denitrogenation catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Suspended Bed Pretreatment Step. Waste oil is pre-hydrogenated in a suspended bed reactor in the presence of a hydrogenation catalyst. The conditions for this step are: temperature 300~380℃, pressure 6~12MPa, hydrogen-to-oil ratio 500~1500 Nm. 3 / m 3 Liquid hourly space velocity (LISH) 0.5~2.0 h⁻¹ -1 ; Step 2: Fixed-bed deep hydrogenation step. The pretreated product is fed into a fixed-bed reactor packed with the catalyst for deep hydrogenation, deoxygenation, and denitrogenation. The conditions for the fixed-bed deep hydrogenation step are: temperature 320~420℃, pressure 6~12MPa, and hydrogen-to-oil ratio 800~2000Nm. 3 / m 3 Liquid hourly space velocity (LISH) 0.5~1.5 h⁻¹ -1 In a fixed-bed reactor, the catalyst promotes the generation of overflow hydrogen atoms from the components through hydrogen overflow, which react with the carbon deposit precursor to achieve in-situ self-regeneration, and the surface carbon deposit is maintained at ≤5wt%. The reaction products are fractionated to obtain bio-jet fuel products.