Non-supported multifunctional catalyst for hydroisomerization and moderate cracking of biological oil and fat and preparation method of non-supported multifunctional catalyst

Abstract

The invention discloses a non-supported multifunctional catalyst for hydroisomerization and moderate cracking of biological oil and fat and a preparation method of the non-supported multifunctional catalyst, and belongs to the technical field of biomass energy catalysis. The catalyst is non-supported Ni1MoxMy, x is more than or equal to 1 and less than or equal to 2, y is more than 0 and less than or equal to 0.5, and metal M is one of Mn, Zn and Fe. The preparation method comprises the following steps: (1) uniformly mixing solid compounds containing nickel and molybdenum, adding the mixture into deionized water, heating and stirring, and adjusting the pH value to 10-11 by using ammonia water to form a blue transparent nickel-molybdenum ammonia complex solution; (2) adding a solid compound containing metal M such as iron and manganese, and continuously stirring until slurry is formed; and (3) filtering, washing, drying and roasting the slurry, extruding and molding, and roasting to obtain the non-supported multifunctional catalyst for hydroisomerization and moderate cracking. The method disclosed by the invention is simple in preparation process and low in raw material price, can realize production of biodiesel or biological aviation kerosene by hydroisomerization and moderate cracking of the biological oil and fat, avoids the problems of excessive cracking and the like in conventional reaction, and has industrial application potential.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomass energy catalysis, and particularly relates to a non-supported multifunctional catalyst for the hydrogenation deoxygenation, hydrogenation isomerization and moderate cracking of bio-oil and a preparation method thereof. BACKGROUND

[0002] Energy, as an important material basis for human survival and social development, has always been widely concerned. With the rapid growth of economy, the acceleration of industrialization and the continuous advancement of urbanization, energy consumption has increased significantly. The overuse of fossil fuels has led to a series of serious problems, including increased greenhouse gas emissions, intensified climate change and decreased energy supply security, which has prompted mankind to seek sustainable and renewable alternative energy sources. In this context, the development of clean energy and low-carbon technology has become a global consensus. Bio-oil and biomass are considered as one of the ideal alternatives to fossil fuels due to their renewability, carbon neutrality and wide sources, so the hydrogenation conversion of bio-oil to biodiesel or bio-jet fuel is currently a hot research topic.

[0003] Traditional biodiesel has poor low-temperature fluidity and insufficient oxidation stability, which limits its application range. Hydroprocessing technology can convert bio-oil into renewable hydrocarbon fuels with high cetane number and excellent low-temperature performance through deoxygenation, isomerization and cracking reactions, and the key lies in the optimization of catalyst performance. Hydrodeoxygenation catalysts can be divided into noble metals, oxides, sulfides, carbides, nitrides and phosphides according to the active components. Noble metal (such as Pt, Pd) catalysts exhibit excellent bio-oil hydrogenation deoxygenation performance (good low-temperature activity and high alkane selectivity), but the disadvantages of noble metals (high cost, poisoning, low high-temperature resistance) limit their industrial application. Phosphide, carbide and nitride catalysts have similar catalytic deoxygenation performance as noble metal catalysts and have also received extensive attention. However, pollution is easily generated during catalyst preparation and use, or harsh preparation conditions are required. Sulfide catalysts exhibit excellent efficiency and cost-effectiveness and are widely used in industrial processes, but sulfur pollution is generated during catalyst synthesis, and sulfur is also introduced into the final product, resulting in increased processing costs of subsequent products and affected environmental performance of the products. Therefore, people attach great importance to the development of high-performance catalysts based on unsulfided transition metals.

[0004] Chinese patent CN 115970750 A provides a preparation method of a zeolite molecular sieve-based catalyst, which synthesizes SAPO-11 molecular sieve through transition metal isomorphous substitution crystallization, and then loads platinum metal to prepare a molecular sieve multifunctional catalyst, which can make the bio-oil deoxygenation rate of bio-oil one-step hydrogenation deoxygenation isomerization reaction reach 100%, C 15 -C 18The selectivity for hydrocarbons was as high as 99.6%, but the selectivity for isomeric hydrocarbons was low, at only 34.8%. Chinese patent CN 115301234 B discloses a supported catalyst prepared by surfactant-induced alloying. This catalyst uses one or more of polyvinylpyrrolidone, polyethylene glycol, and sodium dodecyl sulfonate as surfactants to hydrothermally induce the formation of PtSn alloy colloids, which are then supported on commercial SAPO-11 molecular sieves. The selectivity for isomeric hydrocarbons reached 63%, but the catalyst products were mostly composed of C. 15 -C 18 It is not suitable for direct use in bio-jet fuel (C8-C). 16 Therefore, it is necessary to develop a pollution-free, highly hydroisomerized, and moderately cracked multifunctional catalyst for the hydrogenation of bio-oils to produce alkane compounds in the range of bio-jet fuel, thereby improving the yield and low-temperature fluidity of bio-jet fuel and green diesel. Summary of the Invention

[0005] The purpose of this invention is to provide a non-supported multifunctional catalyst with adjustable metal composition and simple preparation process. By optimizing the Ni-Mo-M ternary metal synergistic mechanism, it can realize the one-step efficient conversion of bio-oils into high-value-added isoalkanes, while improving isomerization selectivity to improve the low-temperature fluidity of the product, inhibiting the generation of low-carbon hydrocarbons below C8 caused by excessive cracking, reducing dependence on precious metals, and achieving high-performance catalysis with inexpensive transition metals.

[0006] The present invention is implemented using the following technical solution:

[0007] S1: In a reactor, molybdenum trioxide (ammonium molybdate or molybdenum trioxide or molybdic acid) and nickel acetate (basic nickel carbonate or nickel nitrate) are mixed evenly in a molar ratio of Ni:Mo=1:(1~2). Under continuous stirring, both are added to deionized water at 50~80 °C to form a mixed slurry. Then, under constant temperature of 70~120 °C and stirring speed of 300~600 rpm, an ammonia solution of a certain concentration is injected using an injection pump. The pH value of the reaction system is dynamically monitored and precisely controlled at 10.0~11.0 until all solid substances are completely dissolved, forming a uniform and stable blue transparent nickel-molybdenum-ammonia complex solution.

[0008] S2: Under the same temperature and vigorous stirring (400~800 rpm), add an aqueous solution of salt M (M is one of Mn, Zn or Fe) to the blue transparent complex solution obtained in step S1 using a constant flow pump; after the addition is complete, age the reaction system at 70~120 °C for 3~6 hours, control the pH value of the solution in the range of 6~8, and finally form a slurry with uniform viscosity;

[0009] S3: The slurry obtained in step S2 is filtered by vacuum pump, washed with water 3 to 5 times, and then dried at 80 to 100 °C for 2 to 4 hours to remove most of the free water. Then the temperature is raised to 120 to 150 °C and dried for another 6 to 10 hours to ensure the stabilization of the precursor framework structure, and a dry catalyst precursor powder is obtained.

[0010] S4: The precursor powder dried in step S3 is thoroughly mixed with one or more of guar gum powder, carbon black powder, carboxymethyl cellulose or starch using a pulverizer. After kneading, it is extruded into strips with a diameter of 1.0~2.0 mm using an extruder.

[0011] S5: The shaped catalyst precursor is placed in a muffle furnace and heat-treated in a flowing air atmosphere: the temperature is raised from room temperature to 250~350 °C and held for 1~2 hours to completely remove impurities such as bound water and acetate ions; then the temperature is raised to the final calcination temperature of 400~550 °C and held for calcination for 3~6 hours; after calcination, the temperature is naturally cooled to room temperature to obtain the multifunctional unsupported bio-oil hydroisomerization and moderate cracking catalyst.

[0012] S6: The multifunctional catalyst for the hydroisomerization and moderate cracking of bio-oils needs to be activated in a hydrogen atmosphere before use. The specific activation conditions are: pressure 1~4 MPa, temperature 300~500 °C, time 6~10 h.

[0013] The unsupported multifunctional catalyst prepared using the above steps, in step S2, is slowly pumped in using a constant flow pump to induce the introduction of metal ions (Mn²⁺ / Zn²⁺ / Fe²⁺). / ³⁺) undergoes a slow hydrolysis-coordination-coprecipitation reaction with the nickel-molybdenum ammonia complex, rather than a simple physical mixing; the aging process causes the active metal to undergo a dynamic process of "dissolution-recombination-gelation-dehydration", and the final paste is an amorphous nickel-molybdenum-M hydroxy oxide precursor.

[0014] Optionally, the metal compound is a metal salt or metal oxide containing nickel, molybdenum, manganese, zinc, or iron;

[0015] Optionally, in step S1, the ratio of nickel-containing compound to molybdenum-containing compound is 1:(1~2), preferably 1:(0.9~1.6); the concentration of ammonia water used in the injection pump is 15~25 wt%; the molar ratio of M salt to Ni in step S2 is (0.1~0.5):1;

[0016] Optionally, the amount of guar gum powder, carbon black powder, carboxymethyl cellulose or starch added in step S4 is 1 to 5 wt% of the precursor powder, preferably 2 to 3%.

[0017] Compared with the prior art, the beneficial effects of the present invention include, but are not limited to:

[0018] This invention utilizes the synergistic effect between transition metals Ni and Mo and non-noble metals Mn, Zn, and Fe to optimize catalyst performance. The prepared catalyst exhibits multiple functions, including hydrodeoxygenation, hydroisomerization, and moderate pyrolysis, and possesses high activity and stability. It effectively removes oxygen from bio-oils while improving isomerization activity, reducing pyrolysis selectivity, increasing the isomer-to-proportional ratio of products, and generating high-quality fuel. Furthermore, the unsupported Ni1Mo catalyst employed... x M y The catalyst has the characteristics of multiple active sites and high catalytic activity, eliminating the need for precious metals and supports, thus reducing raw material costs. Attached Figure Description

[0019] Figure 1 The X-ray diffraction (XRD) patterns of the catalysts synthesized in Comparative Example 1 and Examples 1-5 are shown. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments, but it should be noted that the content of the present invention is not limited thereto.

[0021] Comparative Example 1

[0022] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in to control the pH of the reaction system at 10.0~11.0, forming a stable nickel-molybdenum ammonia complex solution. Stirring was continued for 5 h until a homogeneous slurry was formed. After filtration, washing, and drying, the slurry was mixed with guar gum powder. After kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, the mixture was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Let's denote it as Cat-1.

[0023] Example 1

[0024] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in, controlling the pH of the reaction system at 10.0~11.0 to form a stable nickel-molybdenum ammonia complex solution. An aqueous solution containing 1.47 g of manganese acetate was then pumped in, and the mixture was aged at 100 °C for 5 h until a homogeneous slurry was formed. After mixing and kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, it was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Mn 0.1 Let's denote it as Cat-2.

[0025] Example 2

[0026] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in, controlling the pH of the reaction system at 10.0~11.0 to form a stable nickel-molybdenum ammonia complex solution. An aqueous solution containing 1.32 g of zinc acetate was then pumped in, and the mixture was aged at 100 °C for 5 h until a homogeneous slurry was formed. After mixing and kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, it was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Zn 0.1 It is denoted as Cat-3.

[0027] Example 3

[0028] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in, controlling the pH of the reaction system at 10.0~11.0 to form a stable nickel-molybdenum ammonia complex solution. An aqueous solution containing 1.36 g of ferric acetate was then pumped in, and the mixture was aged at 100 °C for 5 h until a homogeneous slurry was formed. After mixing and kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, it was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Fe 0.1 It is denoted as Cat-4.

[0029] Example 4

[0030] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in, controlling the pH of the reaction system at 10.0~11.0 to form a stable nickel-molybdenum ammonia complex solution. An aqueous solution containing 4.08 g of ferric acetate was then pumped in, and the mixture was aged at 100 °C for 5 h until a homogeneous slurry was formed. After mixing and kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, it was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Fe 0.3 It is denoted as Cat-5.

[0031] Example 5

[0032] In a reactor, 14.93 g of nickel acetate and 12.96 g of molybdenum trioxide were mixed evenly, and 50 mL of deionized water at 80 °C was added. The mixture was stirred at 80 °C for 1 h to form a slurry. Subsequently, under constant temperature of 80 °C and stirring speed of 500 rpm, a 20 wt% ammonia solution was pumped in, controlling the pH of the reaction system at 10.0~11.0 to form a stable nickel-molybdenum ammonia complex solution. An aqueous solution containing 6.81 g of ferric acetate was then pumped in, and the mixture was aged at 100 °C for 5 h until a homogeneous slurry was formed. After mixing and kneading, the mixture was extruded into strips and transferred to a muffle furnace for programmed temperature calcination for 4 h. After cooling, it was activated at 300 °C under a 1 MPa hydrogen atmosphere for 8 h to obtain the catalyst Ni1Mo. 1.5 Fe 0.5 It is denoted as Cat-6.

[0033] Example 6

[0034] In a fixed-bed reactor, a 40 wt% methyl palmitate / cyclohexane mixed solution was used as the raw material, and the reaction was carried out at a temperature of 340 °C, a hydrogen pressure of 1 MPa, and a liquid hourly space velocity of 1.2 h⁻¹. -1 The hydrogenation reaction performance of 5 mL catalyst was evaluated under the condition of a hydrogen-to-oil ratio of 500:1.

[0035] Using methyl palmitate as a raw material, the catalytic reaction performance results of Comparative Example 1 and Examples 1-5 are shown in Table 1. Where ≤C7 represents the content of all alkanes with 5-7 carbon atoms in the product, and n-C8~C6 represents the content of alkanes with 8-7 carbon atoms in the product. 16 The content of 8-16 n-alkanes in the product, i-C8~C 16The i / n ratio represents the content of 8-16 isoalkanes in the product, where i is i-C8~C9. 16 / n-C8~C 16 The value of C8~C 16 All are alkanes within the jet fuel distillate range.

[0036] Table 1. Catalytic reaction performance results of Examples 1-5 and Comparative Example 1

[0037]

[0038] The data in the table above shows that Ni1Mo in Comparative Example 1 1.5 The catalyst exhibits a strong tendency for cracking and isomerization. The proportion of light components (C5-C7) in its products is as high as 36.4%, with an isomerization index (i / n) of 6.31. However, due to its high cracking activity, the yield of the target long-chain isoalkanes is limited. Introducing specific metal promoters can significantly regulate the hydroisomerization reaction pathway, achieving decoupled control of isomerization selectivity and cracking activity. All examples maintained 100% deoxygenation rate, demonstrating that the addition of promoters did not affect the deoxygenation activity of the main catalyst. However, by changing the reaction network, the targeted optimization of the target product distribution was successfully achieved. Compared with Comparative Example 1, the content of light components ≤C7 in the products was significantly reduced after the addition of the metal promoter. The Mn and Fe modified catalysts in Examples 1, 3, 4, and 5 showed a significant decrease in the content of light components ≤C7, indicating effective suppression of cracking reaction pathways such as β-fracture. Comparison of product distributions revealed that although the i / n value decreased, the isomer components in the products increased to varying degrees. This is due to the reduction in light hydrocarbon components and the increase in jet fuel selectivity. Among them, Ni1Mo in Example 4 1.5 Fe 0.3 The catalyst exhibits excellent light hydrocarbon suppression performance, approaching that of Example 5 (Ni1Mo). 1.5 Fe 0.5 The extreme inhibition level (≤C7=2.7%) was maintained while a higher isomerization selectivity was achieved. This seemingly contradictory phenomenon reveals the unique mechanism of action of Fe promoters: while inhibiting the cracking reaction, they regulate the reaction pathway selectivity, allowing more carbon chains to generate branched alkanes through isomerization, rather than generating light hydrocarbons.

[0039] By adjusting the type and proportion of auxiliary metals, the reaction network is reconstructed, through Ni1Mo 1.5 Fe y The construction of the three-way catalyst system successfully achieved synergistic regulation of the cracking-isomerization pathway in the hydrodeoxygenation reaction network, solving the problem of low isomerization rate caused by excessive cracking of the basic NiMo catalyst, and significantly improving the distillation range of the target product—aviation kerosene (C8~C4). 16The selectivity and yield of the catalyst are improved. Different third metals and their contents have varying effects on the regulation of cracking and isomerization activity, providing an important basis for designing and optimizing catalysts to meet specific target product distribution requirements. The catalyst system of this invention exhibits significant advantages in the production of high-value-added biofuels such as biojet fuel / diesel.

[0040] The above description is a detailed account of the oil hydroisomerization and moderate cracking catalyst provided by this invention. It should be noted that the above embodiments are exemplary and not intended to limit the invention; the scope of protection of this invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A non-supported multifunctional catalyst for the hydroisomerization and moderate cracking of bio-oils, characterized in that... The catalyst has a metal molar composition of Ni1Mo. x M y The metal M is one of Mn, Zn, and Fe, and the preparation method of the catalyst includes the following steps: S1: Mix the nickel-containing compound and the molybdenum-containing compound evenly in a certain proportion; under continuous stirring, add both into deionized water at 50~80 °C to form a mixed slurry; then, under constant temperature of 70~120 °C and stirring speed of 300~600 rpm, inject an ammonia solution of a certain concentration using a syringe pump, dynamically monitor and precisely control the pH value of the reaction system at 10.0~11.0 until all solid substances are completely dissolved, forming a homogeneous, stable blue transparent nickel-molybdenum ammonia complex solution; S2: Under the same temperature and vigorous stirring (400~800 rpm), add an aqueous solution of salt M (M is one of Mn, Zn or Fe) to the blue transparent complex solution obtained in step S1 using a constant flow pump; after the addition is complete, age the reaction system at 70~120 °C for 3~6 hours, controlling the pH value of the solution in the range of 6~8 during the process, and finally form a slurry with uniform viscosity; S3: The slurry obtained in step S2 is filtered by vacuum pump, washed with water 3 to 5 times, and then dried at 80 to 100 °C for 2 to 4 hours to remove most of the free water. Then the temperature is raised to 120 to 150 °C and dried for another 6 to 10 hours to ensure the stabilization of the precursor framework structure, and a dry catalyst precursor powder is obtained. S4: The precursor powder dried in step S3 is thoroughly mixed with one or more of guar gum powder, carbon black powder, carboxymethyl cellulose or starch using a pulverizer. After kneading, it is extruded into strips with a diameter of 1.0~2.0 mm using an extruder. S5: The shaped catalyst precursor is placed in a muffle furnace and heat-treated in a flowing air atmosphere: the temperature is raised from room temperature to 250~350 °C and held for 1~2 hours to completely remove impurities such as bound water and acetate; then the temperature is raised to the final calcination temperature of 400~550 °C and held for calcination for 3~6 hours; after calcination, the temperature is naturally cooled to room temperature to obtain the multifunctional unsupported bio-oil hydroisomerization and moderate cracking catalyst. S6: The multifunctional catalyst for the hydroisomerization and moderate cracking of bio-oils needs to be activated in a hydrogen atmosphere before use. The specific activation conditions are: pressure 1~4 MPa, temperature 300~500 °C, time 6~10 h.

2. The catalyst according to claim 1, wherein the metal compound is a metal salt or metal oxide containing nickel, molybdenum, manganese, zinc, or iron.

3. In step S1, the ratio of nickel-containing compound to molybdenum-containing compound is 1:(1~2), preferably 1:(0.9~1.6); the concentration of ammonia water used in the injection pump is 15~25 wt%; the molar ratio of M salt to Ni in step S2 is (0.1~0.5):

1.

4. The amount of guar gum powder, carbon black powder, carboxymethyl cellulose or starch added in step S4 is 1 to 5 wt% of the precursor powder, preferably 2 to 3%.

5. The application of the catalyst according to claim 1 in the hydroisomerization and moderate cracking of oils to produce hydrocarbon-based biodiesel or biojet fuel; wherein the temperature of the hydrogenation reaction is 280~360 °C and the hydrogen pressure is 1~5 MPa; wherein the oils include animal and vegetable oils.

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