Method for preparing biological aviation oil by promoting algal oil conversion by utilizing pyrolysis activated nickel particles
By pyrolyzing and activating nickel particle catalysts, nitrogen-rich nickel-containing carbon sheets (Ni-NC) were prepared, which solved the problem of low energy density in microalgal lipid transesterification, realized the efficient conversion of algal oil into biofuel, improved the conversion rate and selectivity, and reduced costs.
Patent Information
- Application Number
- CN202510845435.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-23
- Publication Date
- 2025-11-07
AI Technical Summary
In existing technologies, fatty acid methyl esters obtained from microalgal oil transesterification have high oxygen content and long carbon chains, resulting in low energy density and poor low-temperature performance, which limits the large-scale application of microalgal oil in the production of biofuel.
A pyrolysis-activated nickel particle catalyst was used to prepare nitrogen-rich nickel-carbon sheets (Ni-NC). By replacing the H2 atmosphere with a CO2 atmosphere, the deoxygenation and bond-breaking efficiency was improved, as well as the dispersion of nickel nanoparticles and the utilization rate of active sites in the catalyst. Pyridine nitrogen and pyrrole nitrogen active sites were formed, which promoted the conversion of algal oil into biofuel.
It improved the conversion rate and product selectivity of algal oil to bio-aviation fuel, increasing the conversion efficiency by more than 24% and the product selectivity by more than 42%, while reducing the amount of catalyst used and the reaction cost.
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Figure CN120904918A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of microalgae bio-jet fuel, and particularly relates to a method for promoting conversion of algal oil into bio-jet fuel by using pyrolysis-activated nickel particles. BACKGROUND
[0002] As a new bio-jet fuel preparation technology, algal oil bio-jet fuel has attracted extensive attention in recent years. Algae have high photosynthetic efficiency and rich oil content, and are rich in biological diversity. Microalgae have strong environmental adaptability and can grow rapidly in fresh water, waste water, sea water and other water bodies, and can survive in extreme conditions such as high temperature. In addition, microalgae can be cultivated in marginal lands such as saline-alkali land, tidal flat and desert, without occupying arable land resources. The oil production rate of microalgae is significantly higher than that of other biological energy sources. During the metabolic process of microalgae, a variety of high-value chemicals can be derived when the key precursors of bio-jet fuel are generated, and an algal-based full-component high-value utilization system can be constructed.
[0003] A major reason for limiting the industrial application of microalgae bio-jet fuel is that the fatty acid methyl ester obtained by transesterification of microalgae oil has high oxygen content and long carbon chain, resulting in low energy density and poor low-temperature performance. How to quickly realize the deoxygenation and bond breaking reaction of microalgae oil has become a key problem for promoting the large-scale application of microalgae oil in the preparation of bio-jet fuel. At present, a variety of catalysts have been studied in the field of bio-jet fuel to realize the deoxygenation and bond breaking of bio-jet fuel precursors.
[0004] The deoxygenation of biological oil under high temperature conditions is mainly completed on the active sites of metals, and nickel metal ranks second after noble metals in the order of catalytic activity. Metal-organic framework catalysts contain both metal and acid sites, the metal sites are highly dispersed, and the amount of metal required in the synthesis process can be effectively reduced, and high catalytic activity can be maintained. However, the pore structure of nickel-based metal-organic framework is lacking, the hydrothermal stability is poor, the deoxygenation and bond breaking performance of the coordinated nickel ions is poor, and the product selectivity is low. Highly active metal nanoparticles can be efficiently obtained by directly pyrolyzing metal-organic frameworks. Studies have shown that pyrolysis of modified metal-organic frameworks can synthesize composite materials suitable for deoxygenation reactions. Although the content of active substances is increased after pyrolysis, the single active substance cannot realize the synergistic catalysis between active components, which to some extent limits the catalytic performance.
[0005] Therefore, the present application proposes a new scheme to apply pyrolysis metal-organic framework catalysts to large-scale algal oil bio-jet fuel. SUMMARY
[0006] The technical problem to be solved by the present application is to overcome the deficiencies in the prior art, and to provide a method for promoting conversion of algal oil into bio-jet fuel by using pyrolysis-activated nickel particles.
[0007] To solve the above technical problems, the solution of the present application is:
[0008] The application provides a preparation method of a catalyst for promoting conversion of algal oil into bio-jet fuel, which comprises the following steps: dissolving nickel nitrate hexahydrate Ni(NO3)2*6H2O and 2-amino terephthalic acid in N,N-dimethylformamide DMF, and then adding the solution into a hydrothermal reactor, and reacting at 140-160 DEG C for 35-37 h; after cooling to room temperature, separating the solid and drying to obtain a nickel-rich amino terephthalic acid framework Ni-NH2-BDC; and then transferring the framework into a tube furnace, pyrolyzing under an inert atmosphere and at 400-600 DEG C for 1-3 h, and obtaining a black powder as the nitrogen-containing nickel-rich carbon sheet Ni-NC used as the catalyst.
[0009] As a preferred scheme of the present application, the mass ratio of the nickel nitrate hexahydrate to the 2-amino terephthalic acid in the reaction solution added into the hydrothermal reactor is 9-10:7-8.
[0010] As a preferred scheme of the present application, the mixed product after reaction is poured into a centrifugal bottle, and centrifugal treatment is carried out at a rotating speed of 8000-10000 rpm for 5-10 min, and the solid precipitate is separated from the supernatant.
[0011] As a preferred scheme of the present application, the separated solid is placed into a blast drying oven, and the drying temperature is 50-70 DEG C.
[0012] As a preferred scheme of the present application, the heating rate is controlled to be 5-15 DEG C / min during the heating stage of pyrolysis.
[0013] As a preferred scheme of the present application, argon is continuously filled during the pyrolysis process, and the gas flow rate is 35-60 mL / min.
[0014] The application further provides a method for promoting conversion of algal oil into bio-jet fuel by using the catalyst prepared by the above method, which comprises the following steps: adding algal oil and the nitrogen-containing nickel-rich carbon sheet Ni-NC used as the catalyst into a reactor, and stirring uniformly; sealing the reactor, and introducing pure CO2 gas until the pressure is 1-4 MPa; reacting at 410-430 DEG C for 6-9 h, and naturally cooling to room temperature, and then exhausting the gas; and centrifugally separating the reaction product, and the obtained liquid phase product is a hydrocarbon corresponding to typical components of bio-jet fuel.
[0015] As a preferred scheme of the present application, the algal oil is any one of methyl palmitate, methyl oleate or biodiesel.
[0016] As a preferred scheme of the present application, the mass ratio of the algal oil to the catalyst is 3-5:0.04-0.2.
[0017] Principle of the application:
[0018] The present application is to add a bifunctional catalyst in the process of converting algal oil methyl palmitate into bio-jet fuel, to improve the deoxygenation and breaking efficiency; the metal acidic bifunctional catalyst adopts pyrolysis treatment of amino terephthalic acid framework, in the bifunctional catalyst, the coordinated nickel ions are reduced to nickel nanoparticles anchored on the carbon sheet, and the amino groups are converted into pyridine nitrogen and pyrrole nitrogen, so that the conversion rate and product selectivity of algal oil deoxygenation and breaking for jet fuel are improved. Specifically as follows:
[0019] 1、The present application uses nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and 2-amino terephthalic acid precursor solution to prepare amino terephthalic acid framework through hydrothermal reaction, and uses pyrolysis of amino terephthalic acid framework to prepare nitrogen-containing nickel-rich carbon sheet. Through testing, the physicochemical properties of the carbon sheet have a porous structure, the coordinated nickel ions are reduced to nickel nanoparticles anchored on the carbon sheet, and active pyridine nitrogen and pyrrole nitrogen are formed at the same time. The active nitrogen atoms contained in the pyridine nitrogen and pyrrole nitrogen can interact with sp 2 Carbon is combined through bond interaction and provides additional electrons to the carbon skeleton, which has strong deoxygenation and breaking catalytic ability. Therefore, the nitrogen-containing nickel-rich carbon sheet prepared by the present application has dispersed metal active sites and acidic active sites, which can be applied to various catalytic application scenarios.
[0020] 2、In the prior art, when pyrolyzing metal organic framework nanomaterials, the obtained nanomaterial particles are usually large (usually 15-30 nm), and the intention is to obtain nanomaterial particles loaded with high-activity metal through pyrolysis of metal organic framework, so as to improve the catalytic performance. However, the size of the nanoparticles indicates that there is an agglomeration phenomenon, which leads to the fact that part of the metal active sites are wrapped by carbon nanomaterials. The pyridine nitrogen and pyrrole nitrogen derived from the amino group can reduce the particle size of the nickel-rich carbon sheet to about 8 nm, so as to further disperse the metal active sites. Not only more nickel metal particles are activated, but also the utilization rate of the original metal active sites is improved, and new active components are introduced synchronously. From another angle, in the case of the same jet fuel yield, the amount of catalyst used in the process of converting algal oil into jet fuel can be reduced.
[0021] 3、In the process of catalyzing algal oil to convert into bio-jet fuel, CO2 atmosphere is selected instead of the commonly used H2 atmosphere, which not only reduces the danger of the high-temperature reaction, but also reduces the transportation cost and storage cost of the reaction atmosphere. And under CO2 atmosphere, the conversion rate and product selectivity of the nitrogen-containing nickel-rich carbon sheet in the process of catalyzing algal oil deoxygenation and breaking to prepare jet fuel can all maintain a high level.
[0022] Compared with the prior art, the present application has the following beneficial effects:
[0023] 1、The present application prepares nitrogen-containing nickel-rich carbon sheets by pyrolyzing an amino terephthalic acid framework, reduces the coordinated nickel ions to nickel nanoparticles anchored on the carbon sheets, and forms active pyridine nitrogen and pyrrole nitrogen at the same time, which can disperse active sites and improve the conversion rate and product selectivity of algal oil conversion to aviation oil.
[0024] 2、The present application disperses active sites by pyridine nitrogen and pyrrole nitrogen derived from amino groups, reduces the particle size of nickel-rich carbon sheets, improves the utilization rate of original metal active sites, and activates more nickel particles to introduce new active components.
[0025] 3、Through a large number of experiments and production practice verification, the method of the present application can improve the conversion efficiency of algal oil conversion to bioaviation oil by more than 24%, and the product hydrocarbon selectivity is improved by more than 42%. Therefore, the present application not only proposes a new material preparation and application method, but also promotes the development of algal oil conversion to aviation oil industry. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 It is the high-resolution transmission electron microscope image of Ni-NH2-BDC and Ni-NC-500 in Example 1.
[0027] Figure 2 It is the X-ray diffraction (XRD) spectrum of Ni-NH2-BDC and Ni-NC-500 in Example 1.
[0028] Figure 3 It is the thermogravimetric curve of Ni-NH2-BDC and Ni-NC-500 in Example 1.
[0029] Figure 4 It is the infrared spectrum of Ni-NH2-BDC and Ni-NC-500 in Example 1.
[0030] Figure 5 It is the high-resolution XPS spectrum of Ni 2p orbit and N1s orbit of Ni-NH2-BDC and Ni-NC-500 in Example 1.
[0031] Figure 6 It is the conversion efficiency and product selectivity comparison of methyl palmitate conversion experiments using different catalysts.
[0032] Figure 7 It is the conversion efficiency and product selectivity comparison of different algal oil conversion experiments. DETAILED DESCRIPTION
[0033] The present application will be further described in detail below in combination with the drawings and specific embodiments:
[0034] 1、Summary of the implementation scheme of the present application
[0035] The present application is to improve the deoxygenation and breaking efficiency in the process of converting algal oil methyl palmitate into bio-jet fuel by adding a bifunctional catalyst; the metal acidic bifunctional catalyst adopts a pyrolysis treatment of an amino terephthalic acid framework, in which the coordinated nickel ions are reduced to nickel nanoparticles anchored on carbon sheets, and the amino groups are converted into pyridine nitrogen and pyrrole nitrogen, so that the conversion rate and product selectivity of algal oil deoxygenation and breaking for bio-jet fuel are improved.
[0036] (1) The present application is a preparation method of a catalyst for promoting the conversion of algal oil into bio-jet fuel, comprising:
[0037] Ni(NO3)2·6H2O and 2-amino terephthalic acid are dissolved in N,N-dimethyl formamide DMF, and then added into a hydrothermal reactor, the mass ratio of Ni(NO3)2·6H2O and 2-amino terephthalic acid in the reaction solution is 45-50:35-40, and the reaction is carried out at 140-160℃ for 35-37h; after cooling to room temperature, the mixed product after reaction is poured into a centrifuge bottle, and centrifugal treatment is carried out at a speed of 8000-10000rpm for 5-10min, and the solid precipitate is separated from the supernatant. The separated solid is placed in a blast drying oven and dried at 50-70℃ to obtain a nickel-rich amino terephthalic acid framework Ni-NH2-BDC.
[0038] Ni-NH2-BDC is transferred to a tube furnace, argon gas is continuously filled, and the gas flow rate is 35-60mL / min. The temperature is raised to 400-600℃ at a heating rate of 5-15℃ / min, and maintained for 1-3h, and the obtained black powder is a nitrogen-containing nickel-rich carbon sheet Ni-NC used as a catalyst.
[0039] (2) A method for promoting the conversion of algal oil into bio-jet fuel using a Ni-NC catalyst, comprising:
[0040] Algal oil and nitrogen-containing nickel-rich carbon sheet Ni-NC as a catalyst are added into a reaction kettle in a mass ratio of 3-5:0.04-0.2, and stirred uniformly; the reaction kettle is sealed, and pure CO2 gas is introduced until the pressure is 1-4MPa; the reaction is carried out at 410-430℃ for 6-9h, and the gas is exhausted after natural cooling to room temperature; the reaction product is centrifuged, and the obtained liquid phase product is a hydrocarbon corresponding to the typical components of bio-jet fuel.
[0041] As an optional example, the algal oil is any one of methyl palmitate, methyl oleate or biodiesel.
[0042] 2、Examples and comparative examples
[0043] Example 1
[0044] (1) 2.7 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and 2.1 g of 2-amino terephthalic acid (mass ratio 9:7) were respectively dissolved in 60 mL of N,N-dimethylformamide (DMF), and then added to a hydrothermal reactor, and reacted at 140°C for 35 h. After cooling to room temperature, the reaction mixture was poured into a centrifuge bottle, and centrifuged at a speed of 8000 rpm for 5 min to separate the solid precipitate from the solution. The separated solid was placed in a blast drying oven and dried at a temperature of 50°C.
[0045] (2) The dried solid was a nickel-rich amino terephthalic acid framework Ni-NH2-BDC. It was placed in a tube furnace, and a heating rate of 5°C / min was adopted in the heating stage. The flow rate of the inert gas argon was 35 mL / min, the pyrolysis temperature was 500°C, and the pyrolysis was carried out under an argon atmosphere for 2 h. The obtained black powder was a nitrogen-containing nickel-rich carbon sheet Ni-NC-500.
[0046] (3) 3 g of biodiesel and 0.08 g of the catalyst Ni-NC-500 were weighed and added to a high-temperature and high-pressure reactor, and the mixture was stirred uniformly. Then the reactor body and the cover with a pressure gauge were fastened with bolts and gaskets. High-purity CO2 was connected to 1 MPa, and after reaching the reaction temperature of 410°C, the reaction was carried out for 9 h, and then the temperature was naturally cooled to room temperature. After cooling, the gas in the reactor was slowly exhausted, and the mixture of the liquid phase product and the catalyst was taken out of the reactor and placed in a centrifuge tube after high-speed centrifugal filtration separation. The liquid phase product was a hydrocarbon corresponding to the typical components of biodiesel.
[0047] Example 2
[0048] (1) 2.775 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and 2.19 g of 2-amino terephthalic acid (mass ratio 9.25:7.3) were respectively dissolved in 60 mL of N,N-dimethylformamide (DMF) and added to a hydrothermal reactor, and reacted at 150°C for 36 h. After cooling to room temperature, the reaction mixture was poured into a centrifuge bottle, and centrifuged at a speed of 10000 rpm for 8 min to separate the solid precipitate from the solution. The separated solid was placed in a blast drying oven and dried at a temperature of 60°C.
[0049] (2) The dried solid was an amino terephthalic acid framework. It was placed in a tube furnace, and a heating rate of 10°C / min was adopted in the heating stage. The flow rate of argon was 45 mL / min, the pyrolysis temperature was 400°C, and the pyrolysis was carried out under an argon atmosphere for 3 h. The obtained black powder was a nitrogen-containing nickel-rich carbon sheet Ni-NC-400.
[0050] (3) Weigh 5 g of methyl oleate and 0.2 g of catalyst Ni-NC-400, and add them into a high-temperature and high-pressure reaction kettle, and stir the mixture. Then fasten the kettle body and the kettle cover with a pressure gauge with bolts and gaskets. Connect high-purity CO2 to 2 MPa, and after reaching the reaction temperature of 420°C, react for 8 h, and naturally cool to room temperature. After cooling is completed, slowly exhaust the gas in the kettle, open the reaction kettle, and use a dropper to take out the mixture of liquid phase product and catalyst into a centrifuge tube, and after high-speed centrifugal filtration separation, the liquid phase product, which is a hydrocarbon corresponding to a typical component of bio-jet fuel, is obtained.
[0051] Example 3
[0052] (1) 3 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and 2.4 g of 2-amino terephthalic acid (mass ratio 10:8) were respectively dissolved in 60 mL of N,N-dimethylformamide (DMF) and added into a hydrothermal reaction kettle, and reacted at 160°C for 37 h. After cooling to room temperature, the mixture after reaction was poured into a centrifuge bottle, and centrifuged at a speed of 9000 rpm for 10 min to separate the solid precipitate from the solution. The separated solid was placed in a blast drying oven for drying at a temperature of 70°C.
[0053] (2) The dried solid is an amino terephthalic acid framework; it is placed into a tube furnace, and the heating rate in the heating stage is 15°C / min, the flow rate of the inert gas argon is 60 mL / min, the pyrolysis temperature is 600°C, and pyrolysis is carried out in an argon atmosphere for 1 h. The obtained black powder is a nitrogen-containing nickel-rich carbon sheet Ni-NC-600.
[0054] (3) Weigh 4 g of methyl palmitate and 0.04 g of catalyst Ni-NC-600, and add them into a high-temperature and high-pressure reaction kettle, and stir the mixture. Then fasten the kettle body and the kettle cover with a pressure gauge with bolts and gaskets. Connect high-purity CO2 to 4 MPa, and after reaching the reaction temperature of 430°C, react for 6 h, and naturally cool to room temperature. After cooling is completed, slowly exhaust the gas in the kettle, open the reaction kettle, and use a dropper to take out the mixture of liquid phase product and catalyst into a centrifuge tube, and after high-speed centrifugal filtration separation, the liquid phase product, which is a hydrocarbon corresponding to a typical component of bio-jet fuel, is obtained.
[0055] Comparative Example 1
[0056] Weigh 4 g of methyl palmitate and 0.04 g of Ni-NH2-BDC, and add them into a high-temperature and high-pressure reaction kettle, and stir the mixture. Then fasten the kettle body and the kettle cover with a pressure gauge with bolts and gaskets. Connect high-purity CO2 to 2 MPa, and after reaching the reaction temperature, react for 8 h, and naturally cool to room temperature. After cooling is completed, slowly exhaust the gas in the kettle, open the reaction kettle, and use a dropper to take out the mixture of liquid phase product and catalyst into a centrifuge tube, and after high-speed centrifugal filtration separation, the liquid phase product is obtained.
[0057] In the present comparative example, other relevant operations and parameters are performed in accordance with the above-described content of Example 1.
[0058] Comparative Example 2
[0059] The pyrolysis catalyst refers to the pyrolysis terephthalic acid framework catalyst proposed by Shao et al., and the pyrolysis is performed at 400℃ for 2h in a tube furnace.
[0060] 4g of methyl palmitate and 0.04g of the pyrolysis catalyst (mass ratio of algal oil to catalyst is 100:1) are weighed and added into a high-temperature and high-pressure reaction kettle, and the mixture is stirred uniformly. Then, the kettle body and the kettle cover with a pressure gauge are fastened with bolts and gaskets. High-purity CO2 is connected to 2MPa, and the reaction is performed for 8h after reaching the reaction temperature, and then the temperature is naturally cooled to room temperature. After the cooling is completed, the gas in the kettle is slowly exhausted, and then the mixture of the liquid phase product and the catalyst is taken out of the reaction kettle and put into a centrifuge tube after the reaction kettle is opened. After high-speed centrifugal filtration separation, the liquid phase product is obtained.
[0061] In the present comparative example, other relevant operations and parameters are performed in accordance with the above-described content of Example 1.
[0062] Comparative Example 3
[0063] The pyrolysis catalyst refers to the pyrolysis terephthalic acid framework catalyst proposed by Shao et al., and the pyrolysis is performed at 600℃ for 2h in a tube furnace.
[0064] 4g of methyl palmitate and 0.04g of the pyrolysis catalyst (mass ratio of algal oil to catalyst is 100:1) are weighed and added into a high-temperature and high-pressure reaction kettle, and the mixture is stirred uniformly. Then, the kettle body and the kettle cover with a pressure gauge are fastened with bolts and gaskets. High-purity CO2 is connected to 2MPa, and the reaction is performed for 8h after reaching the reaction temperature, and then the temperature is naturally cooled to room temperature. After the cooling is completed, the gas in the kettle is slowly exhausted, and then the mixture of the liquid phase product and the catalyst is taken out of the reaction kettle and put into a centrifuge tube after the reaction kettle is opened. After high-speed centrifugal filtration separation, the liquid phase product is obtained.
[0065] In the present comparative example, other relevant operations and parameters are performed in accordance with the above-described content of Example 1.
[0066] 3. Product testing and result analysis
[0067] From Figure 1 and Figure 2 It can be seen from the high-resolution transmission electron microscope image and the X-ray diffraction (XRD) spectrum of the nitrogen-containing and nickel-rich carbon sheet that the nitrogen-containing and nickel-rich carbon sheet with a particle size of 7-11nm is successfully prepared, the nickel single phase appears, and the Ni 2+ is converted to Ni nanoparticles during the ligand pyrolysis process. From Figure 3The thermogravimetric curve of the nitrogen-containing nickel-rich carbon sheet can show that the final mass loss of Ni-NC-500 of Example 1 is not more than 10%, and the thermal stability is improved. From Figure 4 The infrared spectrum of the nitrogen-containing nickel-rich carbon sheet can show that the peaks at 3309 and 3142 cm -1 correspond to the asymmetric and symmetric stretching modes of the N-H bond of the amino group, and the peaks at 1588 and 1402 cm -1 are caused by the asymmetric and symmetric stretching modes of -COO- in the NH2-BDC ligand. When pyrolysis is raised to above 500°C, many bands almost disappear, the original framework collapses, and a two-dimensional carbon nanosheet rich in Ni and N is formed. From Figure 5 The high-resolution XPS spectrum of the Ni 2p and N1s orbitals of the nitrogen-containing nickel-rich carbon sheet can show that after pyrolysis, Ni 2+ is reduced to Ni 0 , the amino group is derived into active pyridine nitrogen and pyrrole nitrogen, which can be combined with sp 2 carbon through bond interaction and provide additional electrons to the carbon skeleton, and has strong deoxidation and bond breaking catalytic ability.
[0068] Figures 6-7 The algal oil conversion analysis data of each example and comparative example are shown in Table 1.
[0069] In order to compare the influence of different catalysts on the conversion efficiency and product selectivity of algal oil in the preparation of bio-jet fuel, the catalysts Ni-NC-500, Ni-NC-400 and Ni-NC-600 prepared in Examples 1-3 were further used for methyl palmitate conversion experiments. Figure 6The differences in the conversion of algal oil by the three catalysts and Comparative Example 1 are shown in the figure. As can be seen from the figure, Comparative Example 1 uses a non-pyrolyzed Ni-NH2-BDC catalyst, and the conversion rate of methyl palmitate is 69.87%, and the selectivity of the product in the aviation oil range is 40.73%. The selectivity of the three examples for target hydrocarbons is better than that of Comparative Example 1, wherein for the Ni-NC-500 catalyst, the conversion rate and target hydrocarbon selectivity are increased to 96.28% and 84.7% respectively, showing the best catalytic effect, which is significantly higher than the catalysts prepared in Examples 1 and 3. For the Ni-NC-400 and Ni-NC-600 catalysts, the conversion rates of methyl palmitate are 94.83% and 98.34% respectively, and the hydrocarbon selectivity is 74.21% and 80.56% respectively. This is because for the catalyst Ni-NC-500, the high-temperature pyrolysis destroys the original Ni-COO structure, and the Ni is reduced to nanoparticles dispersed on the carbon nanosheet, and there are more empty orbitals for the metal center atom, which produces unsaturated coordination to form Lewis acid sites, which has stronger deoxygenation ability and Lewis acid sites. In addition, the catalyst also forms a porous structure on the carbon sheet surface, which enhances the mass transfer of the reactants and promotes the interaction between methyl palmitate and the catalytically active sites.
[0070] Figure 7 In order to compare the conversion efficiency and product selectivity of the Ni-NH2-BDC catalyst of Comparative Example 1 and the Ni-NC-500 catalyst of Example 1 in the conversion experiment of different algal oil components, the differences in the conversion of different algal oils by the catalysts are shown. As can be seen from the figure, the total selectivity of methyl palmitate with a shorter carbon chain is the highest, reaching 84.7%, and the proportion of n-heptadecane in the liquid product is as high as 20%. It is worth noting that the selectivity of methyl oleate with a long carbon chain is as high as 73.38%, and the content of aromatic hydrocarbons and olefins is high, reaching 7.8% and 5.24% respectively. This is because under the CO2 atmosphere, the carbon-carbon double bond of the unsaturated fatty acid methyl ester serves as the initial active site for deoxygenation reaction, promoting the formation of carbon ions and triggering the fragmentation mechanism. In addition, the high content of aromatic hydrocarbons and olefins indicates that hydrogen transfer reactions occur between olefins. In addition, the selectivity of biodiesel is 61.13%, which is due to the presence of more long-chain esters in biodiesel. Both the conversion rate of methyl palmitate (69.87%) and the selectivity of the product in the aviation oil range (40.73%) of the Ni-NH2-BDC catalyst are higher than those of the Ni-NH2-BDC catalyst.
[0071] As can be seen from the data comparison in the chart, the nitrogen-rich nickel-containing carbon sheet prepared by pyrolyzing the amino terephthalic acid framework in the present application not only reduces the coordinated nickel ions to nickel nanoparticles anchored on the carbon sheet, but also forms active pyridine nitrogen and pyrrole nitrogen, which can disperse active sites and improve the conversion rate and product selectivity of algal oil conversion to aviation oil. Compared with the un-pyrolyzed comparative example 1 and the reported pyrolysis catalysts for algal oil conversion to bio-aviation oil in the literature, the best catalyst after pyrolysis in Shao's literature can increase the product selectivity to 78% at 420℃, while the nitrogen-rich nickel-containing carbon sheet prepared by pyrolyzing the amino terephthalic acid framework in the present application can increase the conversion efficiency of algal oil conversion to bio-aviation oil to more than 96% and the product hydrocarbon selectivity to more than 84%.
[0072] Therefore, the present application has the advantages of improving the conversion rate and product selectivity of algal oil and improving the thermal stability of the catalyst and reducing the cost, and can be applied to the scene of large-scale conversion of algal oil to aviation oil.
[0073] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the present application.
Claims
1. A method for the preparation of a catalyst for facilitating the conversion of algal oil into biojet fuel, characterized by, The method comprises the following steps: The nickel nitrate hexahydrate Ni(NO3)2·6H2O and 2-amino terephthalic acid are dissolved in N,N-dimethylformamide DMF, and then added into a hydrothermal reactor, and reacted at 140-160℃ for 35-37h; after cooling to room temperature, the solid is separated and dried to obtain a nickel-rich amino terephthalic acid framework Ni-NH2-BDC; the framework is transferred into a tube furnace, and pyrolyzed at 400-600℃ for 1-3h in an inert atmosphere to obtain a black powder, which is the nitrogen-containing nickel-rich carbon sheet Ni-NC used as a catalyst.
2. The method of claim 1, wherein, The mass ratio of the nickel nitrate hexahydrate to the 2-amino terephthalic acid in the reaction solution added into the hydrothermal reactor is 9-10:7-8.
3. The method of claim 1, wherein, The mixed product after reaction is poured into a centrifuge bottle, and centrifuged at a speed of 8000-10000rpm for 5-10min to separate the solid precipitate from the supernatant.
4. The method of claim 1, wherein, The separated solid is placed into a blast drying oven, and dried at a temperature of 50-70℃.
5. The method of claim 1, wherein, During the heating stage of pyrolysis, the heating rate is controlled to be 5-15℃ / min.
6. The method of claim 1, wherein, Argon is continuously filled during pyrolysis, and the gas flow rate is 35-60mL / min.
7. A process for the conversion of algal oil to bio-jet fuel using the catalyst prepared by the process as claimed in any one of claims 1 to 6, characterized in that, The method comprises the following steps: The algal oil and the nitrogen-containing nickel-rich carbon sheet Ni-NC as a catalyst are added into a reactor, and stirred uniformly; the reactor is sealed, and pure CO2 gas is introduced until the pressure is 1-4MPa; the reaction is carried out at 410-430℃ for 6-9h, and the gas is discharged after natural cooling to room temperature; the reaction product is centrifuged, and the obtained liquid phase product is a hydrocarbon corresponding to typical components of bio-oil.
8. The method of claim 7, wherein, The algal oil is any one of methyl palmitate, methyl oleate or biodiesel.
9. The method of claim 7, wherein, The mass ratio of the algal oil to the catalyst is 3-5:0.04-0.2.