Method for enhanced hydrodenitrogenation of bio-oil

Abstract

The invention discloses a bio-oil enhanced hydrodenitrogenation method, which comprises the following steps: adding bio-oil, a catalyst, formic acid and deionized water into a reaction kettle, uniformly stirring to obtain a mixed solution, continuously stirring for reaction, and after the reaction is finished, carrying out suction filtration and distillation to obtain reformed bio-oil. The preparation method of the catalyst comprises the following steps: mixing corn straw and ammonium molybdate, adding deionized water after mixing, stirring and dipping, and then carrying out vacuum drying and calcining to obtain the catalyst. In the catalytic reforming process, formic acid is innovatively introduced to serve as a hydrogen source, the gas-liquid interface transmission resistance of a traditional gaseous hydrogen source is eliminated through the homogeneous hydrogen supply characteristic of liquid formic acid, the flammable and explosive risk of high-pressure hydrogen is avoided, the process safety is improved, meanwhile, formic acid is subjected to in-situ decomposition on the surface of the catalyst to generate active hydrogen species, and the catalytic reforming efficiency is improved. And a synergistic catalysis mechanism is formed with a platinum-like active site of the catalyst, so that the kinetic advantage of the hydrodenitrification reaction is enhanced, and an efficient, safe and environment-friendly bio-oil hydrodenitrification process system is constructed.

Description

Technical Field

[0001] This invention belongs to the field of bio-oil preparation technology, specifically relating to a method for bio-oil reforming. Background Art

[0002] With economic development and improved living standards, human demand for energy is increasing daily, while fossil fuels are becoming increasingly depleted, and their large-scale use leads to environmental problems. Therefore, renewable energy sources, represented by biomass energy, are attracting increasing attention due to their environmentally friendly and renewable characteristics. The development of efficient and low-cost catalytic systems has always been a core focus of industry research. In traditional catalytic technologies, while noble metal catalysts (such as platinum-based catalysts) possess excellent catalytic activity, their scarcity and high cost severely restrict large-scale industrial applications. Molybdenum carbide, as a transition metal carbide, is considered a potential low-cost alternative due to its similar electronic structure and catalytic properties to noble metals. However, the traditional preparation process of molybdenum carbide has long relied on flammable and explosive gaseous carbon sources such as carbon monoxide (CO) and methane (CH4), or expensive solid carbon sources such as activated carbon. This not only poses significant safety hazards but also results in high catalyst production costs, making economical production difficult.

[0003] Meanwhile, in terms of catalyst structure, traditional molybdenum carbide catalysts often suffer from limitations in preparation processes, resulting in dense catalyst supports with insufficient exposure of active sites and a tendency for metal particles to agglomerate, leading to decreased catalytic activity and stability. These structural defects prevent traditional molybdenum carbide catalysts from fully realizing their platinum-like catalytic potential in practical applications, limiting their effectiveness in important catalytic reactions such as hydrodenitrification.

[0004] In catalytic reaction processes, hydrogen gas is typically used as the hydrogen source in traditional hydrodenitrification processes. However, gaseous hydrogen exhibits significant gas-liquid interface transport resistance in the reaction system, resulting in low diffusion efficiency of hydrogen molecules to the catalyst surface and affecting the reaction kinetics. More importantly, the storage and use of high-pressure hydrogen gas poses significant safety risks due to its flammability and explosiveness. This not only increases the construction and maintenance costs of process equipment but also imposes extremely high safety requirements on the production process, greatly hindering the industrial-scale promotion of related technologies.

[0005] Patent CN 110846070 A discloses a technical solution for hydrogenating crude bio-oil using elemental aluminum as a hydrogen source. The core of the solution is to mix crude bio-oil, which is a product of biomass thermochemical conversion, with elemental aluminum, deionized water, tetrahydronaphthalene, and precious metal catalysts such as Pt / C and Ru / C in a weight ratio of 1:0.21:0.85:4. After purging the air in the reactor with argon, the mixture is heated to 300-450℃ for 1-4 hours. After the reaction is completed and cooled to room temperature, the modified oil is obtained by centrifugation at 10000rpm. However, this scheme has some drawbacks or shortcomings. For example, the precious metal catalysts such as Pt / C and Ru / C used are scarce and expensive, making it difficult to meet the economic requirements of large-scale industrial production. Although using aluminum as a hydrogen source avoids the use of high-pressure hydrogen, aluminum, as a metal raw material, has high consumption costs when used on a large scale. The reaction needs to be carried out at a high temperature of 300-450℃, which requires high heat resistance of the equipment and consumes a lot of energy. The amount of tetrahydronaphthalene used is relatively large (2-6 by weight of crude bio-oil), which can dilute, transfer hydrogen and assist in separation, but will increase the cost of solvent procurement, and subsequent separation and recovery may also bring additional process complexity.

[0006] Patent CN 115894147 B discloses a technical solution for the directional conversion of quinoline and its derivatives into aromatics. The core of the solution is the preparation of a nitrogen-doped carbon-supported pure α-phase molybdenum carbide (α-MoC / NC@NC) catalyst, which is then used to achieve the conversion in a fixed-bed hydrogenation reactor. The process involves calcining urea to prepare graphitic carbon nitride (g-C3N4), followed by the preparation of mesoporous carbon nitride using dicyandiamide, g-C3N4, and nano-silica. This mesoporous carbon nitride is then reacted with ammonium molybdate to obtain the catalyst. The catalyst is then packed into a fixed bed and subjected to a hydrogenation process at an H2 pressure of 3.0-5.0 MPa and a liquid hourly space velocity of 9-15 h⁻¹. -1 Under conditions of a hydrogen / oil volume ratio of 500 / 1-700 / 1 and a temperature of 350-380℃, the catalytic reaction of quinoline and its derivatives achieves a conversion rate and denitrification rate of no less than 99%, and an aromatic selectivity of no less than 90%. However, this approach has certain drawbacks: it requires a high-pressure hydrogen environment of 3.0-5.0 MPa, placing high demands on equipment pressure resistance, increasing equipment costs and safety hazards; the catalyst preparation steps are complex, requiring precise control of various raw material ratios and reaction conditions, making industrial operation difficult and costly; and the reaction temperature of 350-380℃ results in high energy consumption, and prolonged high temperatures may affect the catalyst's lifespan.

[0007] Against this backdrop, the present invention focuses on overcoming the multiple bottlenecks of traditional catalytic technology. Summary of the Invention

[0008] To address the problem of high nitrogen content in biomass oil produced by hydrothermal liquefaction in existing technologies, this invention provides a method for enhanced hydrodenitrification of biomass oil. By using an effective catalyst and reforming method during the hydrothermal liquefaction process, the nitrogen content of the obtained biomass oil is significantly reduced.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A method for enhancing the hydrodenitrification of bio-oil includes the following steps: adding bio-oil, catalyst, formic acid and deionized water into a reaction vessel and stirring until a mixture is obtained; continuing to stir to carry out the reaction; and after the reaction is completed, obtaining the reformed bio-oil by filtration and distillation.

[0011] Furthermore, this invention innovatively introduces formic acid as a hydrogen source in the catalytic reforming process. Liquid formic acid possesses the unique characteristic of homogeneous hydrogen supply, completely eliminating the gas-liquid interface transport resistance of traditional gaseous hydrogen sources and significantly improving the utilization efficiency of the hydrogen source. Simultaneously, formic acid can decompose in situ on the catalyst surface to generate active hydrogen species, forming a synergistic catalytic mechanism with the "platinum-like" active sites of the biomass-based molybdenum carbide catalyst. This synergistic effect not only enhances the kinetic advantages of the hydrodenitrogenation reaction but also completely avoids the safety risks posed by high-pressure hydrogen, constructing a highly efficient, safe, and environmentally friendly bio-oil hydrodenitrogenation process system, providing a novel solution for technological innovation and sustainable development in the field of catalysis.

[0012] Furthermore, the catalyst is biomass-based molybdenum carbide. This invention uses renewable biomass such as corn stalks as a carbon source and synthesizes the biomass-based molybdenum carbide catalyst via a one-step high-temperature pyrolysis calcination method. This method not only avoids the safety hazards and cost issues of traditional carbon sources but also utilizes the natural porous structure of biomass to form a catalyst support with abundant pores during calcination. This porous structure can significantly increase the exposure density of catalytic active sites while effectively inhibiting the agglomeration of metal particles, fundamentally optimizing the physical structure and catalytic performance of the catalyst.

[0013] As a preferred embodiment of the present invention, the mass ratio of bio-oil, catalyst, formic acid, and deionized water is 1:(0.1-0.5):(0.6-1.2):(20-30), preferably 1:0.25:0.9:25. The mass ratio of bio-oil to deionized water of 1:25 effectively balances the system viscosity and reactant concentration, preventing excessively high viscosity from affecting mass transfer efficiency or excessively low concentration from causing a decrease in reaction rate, thereby ensuring sufficient contact between the reactants and the catalyst surface. The mass ratio of formic acid to bio-oil of 0.9:1 provides sufficient active hydrogen species to ensure the efficient hydrodenitrification reaction, reduces side reactions, achieves good synergy with the active sites of the catalyst, and improves the overall catalytic effect.

[0014] As a preferred embodiment of the present invention, the stirring rate is 200 r / min, the reaction temperature is 280℃~300℃, specifically 290℃, the heating rate is 60℃ / hour, and the reaction time is 0.1 hours~3 hours, specifically 1 hour.

[0015] As a preferred technical solution of the present invention, the product after reaction is filtered through an organic filter membrane to obtain a liquid product, and then the liquid product is subjected to rotary evaporation at a temperature of 20℃~25℃ to remove dichloromethane, and finally the upgraded bio-oil is obtained.

[0016] As a preferred technical solution of the present invention, the specific method for preparing the catalyst includes the following steps: mixing corn stalks and ammonium molybdate, adding deionized water for stirring and impregnation, and then vacuum drying and calcining to obtain the catalyst.

[0017] As a preferred embodiment of the present invention, the mass ratio of corn stalks to ammonium molybdate is 10:(9-13).

[0018] As a preferred technical solution of the present invention, the stirring and impregnation time is 4 to 6 hours and the stirring speed is 1500 r / min.

[0019] As a preferred embodiment of the present invention, the vacuum drying time is 1 to 72 hours and the vacuum drying temperature is 90°C.

[0020] As a preferred embodiment of the present invention, the calcination atmosphere is a nitrogen atmosphere. Nitrogen gas is purged for 10 minutes before calcination to purge air from the reactor. The dried mixture is then placed into the reactor. The calcination heating rate is 60°C / hour, the calcination temperature is 700°C-900°C, and the calcination time is 2 hours. Utilizing the naturally porous structure of biomass, a catalyst support with abundant pores is formed during the calcination process.

[0021] The beneficial effects of this invention are as follows: 1. Biomass-based molybdenum carbide achieves "structural biomimicry" with noble metal catalysts through electronic structure modification and surface engineering, possessing "platinum-like" catalytic behavior and low-cost substitution advantages. This invention breaks through the limitations of traditional molybdenum carbide preparation relying on gaseous or solid carbon sources such as CO, CH4, and activated carbon. Using renewable biomass such as corn stalks as carbon sources, biomass-based molybdenum carbide catalysts are synthesized through a one-step calcination method with high-temperature pyrolysis. Its porous structure support can increase the density of catalytic active sites and reduce metal agglomeration. 2. This invention innovatively introduces formic acid as a hydrogen source in the catalytic reforming process. The homogeneous hydrogen supply characteristics of liquid formic acid eliminate the gas-liquid interface transport resistance of traditional gaseous hydrogen sources, avoid the flammability and explosion risks of high-pressure hydrogen, and improve process safety. At the same time, formic acid decomposes in situ on the catalyst surface to generate active hydrogen species, forming a synergistic catalytic mechanism with the "platinum-like" active sites of the catalyst, enhancing the kinetic advantages of hydrodenitrification reaction, and constructing a highly efficient, safe, and environmentally friendly bio-oil hydrodenitrification process system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The VK diagram shows the bio-oil obtained by reforming molybdenum carbide obtained by pyrolysis at 700, 800, and 900°C for 2 hours under a nitrogen atmosphere in this invention.

[0024] Figure 2 The composition and distribution of bio-oil and crude oil obtained by catalysts at different temperatures in this invention are shown. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0027] Unless otherwise specified, all materials and reagents used in the following implementation examples are commercially available.

[0028] This invention also provides a step for preparing bio-oil using hydrothermal liquefaction of biomass: First, biomass raw materials and deionized water are mixed at a mass ratio of 1:5 to 1:10 and then loaded into a high-pressure reactor. The airtightness of the apparatus is checked, and high-purity N2 is introduced to remove air. The mixture is heated to 250-300°C at a heating rate of 5-10°C / min and reacted at a stirring rate of 150-250 r / min and a pressure of 8-15 MPa for 0.5-2 h. After the reaction is completed and cooled, the solid-liquid mixture is separated by vacuum filtration. The liquid phase is extracted 2-3 times with dichloromethane, and then the extractant dichloromethane is removed by rotary evaporation to finally obtain crude bio-oil.

[0029] Example 1

[0030] This example describes the preparation of crude bio-oil, and the specific steps are as follows:

[0031] (1) Weigh 30g of spirulina and 150g of deionized water respectively, mix them and pour them into a 250mL stainless steel high-pressure reactor.

[0032] (2) Check the airtightness of the device, the circuit and the passage are unobstructed. After confirming that the above conditions are good, open the air inlet valve and the air outlet valve, and introduce N2 for 10 minutes.

[0033] (3) Heat to 290℃ (preferred temperature), stir at 200r / min, maintain pressure at 10-12MPa, react for 1h, and generate nitrogen-containing bio-oil through thermochemical conversion.

[0034] (4) Open the reaction vessel, collect the solid-liquid mixture inside the vessel, separate the solid and liquid through a vacuum filtration device, and separate the dichloromethane and bio-oil through a distillation device to obtain bio-oil. The reaction product is then vacuum filtered and distilled with dichloromethane to obtain crude bio-oil.

[0035] Example 2

[0036] This embodiment describes a method for preparing a molybdenum carbide catalyst (calcined at 800°C), and the steps are as follows:

[0037] (1) Mix 9.2g of ammonium molybdate (molybdenum content is 5g) and 10g of corn stalks and add them to 200mL of deionized water; then place them in an ultrasonic cleaner and sonicate for 10min to mix thoroughly; then stir and soak in a magnetic stirrer at 1500r / min for 6h. The mixture obtained after soaking is then dried at a vacuum temperature of 90℃ for 48 hours.

[0038] (2) Grind the dried mixture into powder in a quartz mill, weigh 2g of the dried powder and put it into a tube furnace, then introduce N2 and purge for 10 minutes to remove air from the tube furnace.

[0039] (3) After exhausting the air, maintain the N2 flow rate at 200 mL / min. Start timing when calcination begins, and raise the temperature to 800℃ at a rate of 60℃ / h. Hold for 2 hours.

[0040] (4) After the retention time is reached, the tubular furnace begins to cool down. After reaching room temperature, the N2 gas valve is closed, and the prepared molybdenum carbide is taken out and named 1 / 2 / Mo2C-800.

[0041] Example 3

[0042] This embodiment describes a method for preparing a molybdenum carbide catalyst (calcined at 700°C), and the steps are as follows:

[0043] (1) Mix 9.2g of ammonium molybdate (molybdenum content is 5g) and 10g of corn stalks and add them to 200mL of deionized water; then place them in an ultrasonic cleaner and sonicate for 10min to mix thoroughly; then stir and soak in a magnetic stirrer at 1500r / min for 6h. The mixture obtained after soaking is then dried at a vacuum temperature of 90℃ for 48 hours.

[0044] (2) Grind the dried mixture into powder in a quartz mill, weigh 2g of the dried powder and put it into a tube furnace, then introduce N2 and purge for 10 minutes to remove air from the tube furnace.

[0045] (3) After exhausting the air, maintain the N2 flow rate at 200 mL / min. Start timing when calcination begins, and raise the temperature to 700℃ at a rate of 60℃ / h. Hold for 2 hours.

[0046] (4) After the retention time is reached, the tubular furnace begins to cool down. After reaching room temperature, the N2 gas valve is closed, and the prepared molybdenum carbide is taken out and named 1 / 2Mo2C-700.

[0047] Example 4

[0048] This embodiment describes a method for preparing a molybdenum carbide catalyst (calcined at 900°C), and the steps are as follows:

[0049] (1) Mix 9.2g of ammonium molybdate (molybdenum content is 5g) and 10g of corn stalks and add them to 200mL of deionized water; then place them in an ultrasonic cleaner and sonicate for 10min to mix thoroughly; then stir and soak in a magnetic stirrer at 1500r / min for 6h. The mixture obtained after soaking is then dried at a vacuum temperature of 90℃ for 48 hours.

[0050] (2) Grind the dried mixture into powder in a quartz mill, weigh 2g of the dried powder and put it into a tube furnace, then introduce N2 and purge for 10 minutes to remove air from the tube furnace.

[0051] (3) After exhausting the air, maintain the N2 flow rate at 200 mL / min. Start timing when calcination begins, and raise the temperature to 900℃ at a rate of 60℃ / h. Hold for 2 hours.

[0052] (4) After the retention time is reached, the tubular furnace begins to cool down. After reaching room temperature, the N2 gas valve is closed, and the prepared molybdenum carbide is taken out and named 1 / 2Mo2C-900.

[0053] Example 5

[0054] This embodiment describes a method for preparing a molybdenum carbide catalyst (calcined at 700°C), and the steps are as follows:

[0055] (1) Mix 12.27g ammonium molybdate (molybdenum content is 6.67g) and 10g corn stalks and add them to 200mL of deionized water; then place them in an ultrasonic cleaner and sonicate for 10min to mix thoroughly; then stir and soak in a magnetic stirrer at 1500r / min for 6h. The mixture obtained after soaking is then dried in a vacuum at 90℃ for 48h.

[0056] (2) Grind the dried mixture into powder in a quartz mill, weigh 2g of the dried powder and put it into a tube furnace, then introduce N2 and purge for 10 minutes to remove air from the tube furnace.

[0057] (3) After exhausting the air, maintain the N2 flow rate at 200 mL / min. Start timing when calcination begins, and raise the temperature to 700℃ at a rate of 60℃ / h. Hold for 2 hours.

[0058] (4) After the retention time is reached, the tubular furnace begins to cool down. After reaching room temperature, the N2 gas valve is closed, and the prepared molybdenum carbide is taken out and named 2 / 3Mo2C-700.

[0059] Example 6

[0060] This embodiment describes a method for preparing a molybdenum carbide catalyst (calcined at 800°C), and the steps are as follows:

[0061] (1) Mix 12.27g ammonium molybdate (molybdenum content is 6.67g) and 10g corn stalks and add them to 200mL of deionized water; then place them in an ultrasonic cleaner and sonicate for 10min to mix thoroughly; then stir and soak in a magnetic stirrer at 1500r / min for 6h. The mixture obtained after soaking is then dried in a vacuum at 90℃ for 48h.

[0062] (2) Grind the dried mixture into powder in a quartz mill, weigh 2g of the dried powder and put it into a tube furnace, then introduce N2 and purge for 10 minutes to remove air from the tube furnace.

[0063] (3) After exhausting the air, maintain the N2 flow rate at 200 mL / min. Start timing when calcination begins, and raise the temperature to 800℃ at a rate of 60℃ / h. Hold for 2 hours.

[0064] (4) After the retention time is reached, the tubular furnace begins to cool down. After reaching room temperature, the N2 gas valve is closed, and the prepared molybdenum carbide is taken out and named 2 / 3Mo2C-800.

[0065] Example 7

[0066] This embodiment describes a method for enhancing and denitrogenating bio-oil, the steps of which are as follows:

[0067] (1) Weigh 2g of crude bio-oil prepared in Example 1, 0.5g of molybdenum carbide 1 / 2Mo2C-800, 15mL of formic acid and 50mL of deionized water respectively and add them to the reaction vessel and stir evenly to obtain a mixture.

[0068] (2) Before the reaction, purge with nitrogen for 10 min to remove air and maintain nitrogen pressure at 0.5 MPa. Set the reaction temperature to 290℃ and raise it to the target temperature by programmed heating (heating rate 60℃ / h) to activate formic acid decomposition and catalyst activity. Stir at 200 r / min and react for 1 h.

[0069] (3) After the reaction is completed, the catalyst and liquid products are separated by filtration through an organic filter membrane. The catalyst can be recycled and reused.

[0070] (4) The liquid product is subjected to rotary evaporation (20-25℃) to remove dichloromethane, and the upgraded bio-oil is obtained.

[0071] Elemental analysis of the bio-oil was performed, and the results are shown in Table 1.

[0072] Table 1. Elemental analysis of bio-oil and crude oil (crude bio-oil from Example 1) obtained under the action of 1 / 2Mo2C-800 catalyst.

[0073] catalyst N(％) C(％) H(％) O(％) None 7.11 72.31 7.68 12.90 <![CDATA[1 / 2Mo2C-800]]> 3.96 74.15 9.62 12.27

[0074] Example 8

[0075] This embodiment describes a method for enhancing and denitrogenating bio-oil, the steps of which are as follows:

[0076] (1) Weigh 2g of crude bio-oil prepared in Example 1, 0.5g of molybdenum carbide 1 / 2Mo2C-700, 15mL of formic acid and 50mL of deionized water respectively and add them to the reaction vessel and stir evenly to obtain a mixture.

[0077] (2) Before the reaction, purge with nitrogen for 10 min to remove air and maintain nitrogen pressure at 0.5 MPa. Set the reaction temperature to 290℃ and raise it to the target temperature by programmed heating (heating rate 60℃ / h) to activate formic acid decomposition and catalyst activity. Stir at 200 r / min and react for 1 h.

[0078] (3) After the reaction is completed, the catalyst and liquid products are separated by filtration through an organic filter membrane. The catalyst can be recycled and reused.

[0079] (4) The liquid product is subjected to rotary evaporation (20-25℃) to remove dichloromethane, and the upgraded bio-oil is obtained.

[0080] Elemental analysis of the bio-oil was performed, and the results are shown in Table 2.

[0081] Table 2. Elemental analysis of bio-oil and crude oil obtained under the action of 1 / 2Mo2C-700 catalyst.

[0082] catalyst N(％) C(％) H(％) O(％) None 7.11 72.31 7.68 12.90 <![CDATA[1 / 2Mo2C-700]]> 4.36 74.55 8.72 13.39

[0083] Example 9

[0084] This embodiment describes a method for enhancing and denitrogenating bio-oil, the steps of which are as follows:

[0085] (1) Weigh 2g of crude bio-oil prepared in Example 1, 0.5g of molybdenum carbide 1 / 2Mo2C-900, 15mL of formic acid and 50mL of deionized water respectively and add them to the reaction vessel and stir evenly to obtain a mixture.

[0086] (2) Before the reaction, purge with nitrogen for 10 min to remove air and maintain nitrogen pressure at 0.5 MPa. Set the reaction temperature to 290℃ and raise it to the target temperature by programmed heating (heating rate 60℃ / h) to activate formic acid decomposition and catalyst activity. Stir at 200 r / min and react for 1 h.

[0087] (3) After the reaction is completed, the catalyst and liquid products are separated by filtration through an organic filter membrane. The catalyst can be recycled and reused.

[0088] (4) The liquid product is subjected to rotary evaporation (20-25℃) to remove dichloromethane, and the upgraded bio-oil is obtained.

[0089] Elemental analysis of the bio-oil was performed, and the results are shown in Table 3.

[0090] Table 3. Elemental analysis of bio-oil and crude oil obtained under the action of 1 / 2Mo2C-900T catalyst

[0091] catalyst N(％) C(％) H(％) O(％) None 7.11 72.31 7.68 12.90 <![CDATA[1 / 2Mo2C-900]]> 4.63 73.71 9.68 11.98

[0092] Example 10

[0093] This embodiment describes a method for enhancing and denitrogenating bio-oil, the steps of which are as follows:

[0094] (1) Weigh 2g of crude bio-oil prepared in Example 1, 0.5g of molybdenum carbide 2 / 3Mo2C-700, 15mL of formic acid and 50mL of deionized water respectively and add them to the reaction vessel and stir evenly to obtain a mixture.

[0095] (2) Before the reaction, purge with nitrogen for 10 min to remove air and maintain nitrogen pressure at 0.5 MPa. Set the reaction temperature to 290℃ and raise it to the target temperature by programmed heating (heating rate 60℃ / h) to activate formic acid decomposition and catalyst activity. Stir at 200 r / min and react for 1 h.

[0096] (3) After the reaction is completed, the catalyst and liquid products are separated by filtration through an organic filter membrane. The catalyst can be recycled and reused.

[0097] (4) The liquid product is subjected to rotary evaporation (20-25℃) to remove dichloromethane, and the upgraded bio-oil is obtained.

[0098] Elemental analysis of the bio-oil was performed, and the results are shown in Table 4.

[0099] Table 4. Elemental analysis of bio-oil and crude oil obtained under the action of 2 / 3Mo2C-700 catalyst

[0100] catalyst N(％) C(％) H(％) O(％) None 6.791 73.31 8.378 11.52 <![CDATA[2 / 3Mo2C-700]]> 4.345 74.55 7.719 13.386

[0101] Example 11

[0102] This embodiment describes a method for enhancing and denitrogenating bio-oil, the steps of which are as follows:

[0103] (1) Weigh 2g of crude bio-oil prepared in Example 1, 0.5g of molybdenum carbide 2 / 3Mo2C-800, 15mL of formic acid and 50mL of deionized water respectively and add them to the reaction vessel and stir evenly to obtain a mixture.

[0104] (2) Before the reaction, purge with nitrogen for 10 min to remove air and maintain nitrogen pressure at 0.5 MPa. Set the reaction temperature to 290℃ and raise it to the target temperature by programmed heating (heating rate 60℃ / h) to activate formic acid decomposition and catalyst activity. Stir at 200 r / min and react for 1 h.

[0105] (3) After the reaction is completed, the catalyst and liquid products are separated by filtration through an organic filter membrane. The catalyst can be recycled and reused.

[0106] (4) The liquid product is subjected to rotary evaporation (20-25℃) to remove dichloromethane, and the upgraded bio-oil is obtained.

[0107] Elemental analysis of the bio-oil was performed, and the results are shown in Table 5.

[0108] Table 5. Elemental analysis of bio-oil and crude oil obtained under the action of 2 / 3Mo2C-800 catalyst.

[0109] catalyst N(％) C(％) H(％) O(％) None 6.791 73.31 8.378 11.52 <![CDATA[2 / 3Mo2C-800]]> 4.65 70.67 9.283 15.397

[0110] Definition of bio-oil denitrification rate

[0111]

[0112] Biomass oil M is biomass oil that has not been upgraded with a catalyst, while biomass oil N is biomass oil that has been upgraded with a catalyst.

[0113] like Figure 1 The three catalysts shown all produced bio-oils with N / C and O / C molar ratios lower than those of the feedstocks. 1 / 2Mo2C-800 had the smallest N / C molar ratio of 0.046, indicating that 1 / 2Mo2C-800 had a better denitrification effect. Figure 2 Compared with uncatalyzed, molybdenum carbide catalysts prepared at different temperatures showed that treating microalgae hydrothermal bio-oil reduced nitrogen-containing heterocycles and amides / amines, and increased hydrocarbons and esters. The 1 / 2Mo2C-800 catalyst prepared at 800℃ performed better in reducing nitrogen and increasing hydrocarbons.

[0114] Table 6 shows the bio-oil denitrification rate of the catalysts prepared.

[0115]

[0116]

[0117] Calculations showed that the 1 / 2Mo2C-800 catalyst prepared at 800℃ with a Mo-to-biomass mass ratio of 1:2 achieved a denitrification rate of 44.3%, significantly better than that prepared at 700℃ (38.68%) and 900℃ (34.88%). This result indicates that 800℃ is the optimal final carbonization temperature.

[0118] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for fortifying bio-oil through hydrodenitrogenation, characterized in that... The process includes the following steps: adding bio-oil, catalyst, formic acid and deionized water into a reaction vessel and stirring until a mixture is obtained. The mixture is then stirred and reacted. After the reaction is completed, the bio-oil is obtained by filtration and distillation.

2. The method for fortifying and hydrodenitrogenating bio-oil according to claim 1, characterized in that: Formic acid is used as the hydrogen source, and the catalyst is biomass-based molybdenum carbide.

3. The method for fortifying and hydrodenitrogenating bio-oil according to claim 2, characterized in that: The mass ratio of bio-oil, catalyst, formic acid and deionized water is 1: (0.1-0.5): (0.6-1.2): (20-30).

4. The method for fortifying and hydrodenitrogenating bio-oil according to claim 1, characterized in that: The stirring rate was 200 r / min, the reaction temperature was 280℃~300℃, the heating rate was 60℃ / hour, and the reaction time was 0.1 hours~3 hours.

5. The method for fortifying and hydrodenitrogenating bio-oil according to claim 1, characterized in that: The product after the reaction is filtered through an organic filter membrane to obtain a liquid product. The liquid product is then subjected to rotary evaporation at a temperature of 20℃~25℃ to remove dichloromethane, and finally the upgraded bio-oil is obtained.

6. The method for fortifying and hydrodenitrogenating bio-oil according to claim 1, characterized in that: The preparation method of the catalyst includes the following steps: mixing corn stalks and ammonium molybdate, then adding deionized water for stirring and impregnation, followed by vacuum drying and calcination to obtain the catalyst.

7. The method for fortifying and hydrodenitrogenating bio-oil according to claim 6, characterized in that: The mass ratio of corn stalks to ammonium molybdate is 10:(9-13).

8. The method for fortifying and hydrodenitrogenating bio-oil according to claim 6, characterized in that: The stirring and soaking time is 4 to 6 hours, and the stirring speed is 1500 r / min.

9. The method for fortifying and hydrodenitrogenating bio-oil according to claim 6, characterized in that: The vacuum drying time is 1 to 72 hours, and the vacuum drying temperature is 90°C.

10. The method for fortifying and hydrodenitrogenating bio-oil according to claim 6, characterized in that: The calcination atmosphere is a nitrogen atmosphere. Nitrogen gas is purged for 10 minutes before calcination to purge the air from the reactor. The dried mixture is then placed into the reactor. The calcination heating rate is 60℃ / hour, the calcination temperature is 700℃-900℃, and the calcination time is 2 hours.

Images