CN115888719A - A kind of alumina-supported bimetallic nickel-cobalt catalyst modified by magnesium oxide and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of catalyst synthesis, and particularly discloses a magnesium oxide modified aluminum oxide loaded bimetallic nickel-cobalt catalyst, and a preparation method and application thereof. The catalyst is prepared by adopting an impregnation method, and the method is simple and convenient to operate. The surface property of the alumina is changed by a magnesium oxide modification method, the selectivity of cyclohexanol and derivatives thereof in the product is improved, the interaction between active metal and a carrier is enhanced, and the dispersion of nickel and cobalt particles is promoted. In addition, a nickel-cobalt bimetallic is used as an active component of the catalystCompared with single metal nickel, the activity of the catalyst is obviously improved. Meanwhile, the catalyst still keeps high catalytic activity after 5 times of circulation, and has good stability. The catalyst has excellent catalytic effect on the hydrodeoxygenation reaction of lignin bio-oil, and the hydrogen content is 2MPa H at 300 DEG C ₂ Under the condition, the yield of cyclohexanol and derivatives thereof in the product can reach 65.6wt%.

Description

A kind of alumina-supported bimetallic nickel-cobalt catalyst modified by magnesium oxide and its preparation method and application

technical field

The invention belongs to the technical field of catalyst synthesis, and in particular relates to a magnesium oxide-modified aluminum oxide-loaded bimetallic nickel-cobalt catalyst and a preparation method and application thereof.

Background technique

In today's society, the excessive exploitation and utilization of fossil energy has led to a series of problems such as energy crisis, environmental pollution and greenhouse effect. Therefore, it is urgent to find a clean and renewable energy that can replace fossil energy. Lignin is the most abundant natural aromatic polymer in nature. Lignin can be converted into bio-oil whose main component is aromatic monomer compounds through depolymerization, which has great potential in the preparation of biofuels and platform compounds. potential. However, the bio-oil obtained from lignin depolymerization has a series of problems such as high oxygen content, high viscosity, low calorific value, and instability. Therefore, it needs to be further modified to obtain high value-added chemicals or fuel. Common upgrading methods include hydrodeoxygenation, catalytic cracking, emulsification, esterification, steam reforming, etc. Among them, hydrodeoxygenation has been considered as one of the most promising bio-oil upgrading methods.

At present, most studies focus on the hydrodeoxygenation conversion of lignin bio-oil to produce naphthenic fuels. However, cyclohexanol and its derivatives can be prepared by selectively hydrodeoxygenating lignin bio-oil by constructing new catalysts. Cyclohexanol and its derivatives are not only a typical type of oxygenated fuel, but also can be used as high-value fuel additives; in addition, cyclohexanol can also be used to prepare pharmaceutical intermediates and synthetic raw materials for polymers such as nylon 66. Therefore, the development of a catalyst with high activity, high selectivity and low cost is of great significance to promote the high-value conversion of lignin bio-oil.

Commonly used hydrodeoxygenation catalysts mainly include noble metal (Ru, Pd, Pt, etc.) catalysts and transition metal (Ni, Co, Fe, Cu, etc.) catalysts. Generally speaking, noble metal catalysts have extremely high activity in the hydrodeoxygenation reaction process, and can catalyze the hydrodeoxygenation reaction at a relatively low temperature, avoiding carbon deposition and coking on the catalyst caused by high temperature and catalyst loss. live. However, noble metal catalysts are expensive and easily poisoned. Therefore, the development of transition metal catalysts with high catalytic activity and low cost is the development trend of catalysts. Wang et al. (Energy Environ.Sci., 2012, 5, 8244–8260) used Raney Ni as a catalyst and isopropanol as a solvent to study the hydrodeoxygenation of pine cracking oil to generate cyclic alcohols. Although Raney Ni exhibited high selectivity to cyclic alcohols, the methanol generated after hydrodeoxygenation of phenolic compounds in bio-oil and carboxylic acids in bio-oil could inhibit the catalytic activity of Raney Ni. Galebach et al. (Green Chem., 2020, 22, 8462–8477) dissolved maple wood in supercritical methanol, and used CuMgAlOx catalyst to convert lignocellulose into C2-C10 alcohols at 300 °C and 20 MPa pressure. The yield reaches 70%-80%. Maple conversion yielded an average selectivity of 31% to C6–C10 cyclic alcohols in a semi-continuous flow reactor in the presence of CuMgAlOx catalyst. Although the CuMgAlOx catalyst exhibited good hydrodeoxygenation activity for lignocellulose, the insoluble pyrolysis products produced under harsh reaction conditions reduced the selectivity of cyclic alcohols. Song et al. (Green Chem., 2020, 22, 1662–1670) prepared a layered Nb ₂ O ₅ material supported Ni-based catalyst, which exhibited good hydrodeoxygenation of lignin bio-oil in aqueous phase Activity, and the selectivity of cyclohexanol and its derivatives in the product is high. Although the catalyst can maintain a high selectivity to cyclohexanol compounds, the amount of catalyst used is 10 times that of lignin bio-oil, and the reaction time is long, up to 10h, so the economic benefit of the reaction is low, and there are still room for further improvement.

In summary, the current catalysts for hydrodeoxygenation of lignin bio-oil to prepare cyclohexanols still have the following problems. First of all, the activity of the catalyst is easily inhibited by harsh reaction conditions and components in some bio-oils or hydrodeoxygenation reaction products, resulting in a decrease in catalytic activity; in addition, the conditions of the catalytic hydrodeoxygenation reaction and the amount of catalyst are also important to consider factor. Although some catalysts can maintain a high selectivity to alcohols produced after hydrodeoxygenation of bio-oil, they need to use an excessive amount of catalyst or the reaction time is long, and the economic benefit of catalytic hydrodeoxygenation reaction is low, which is not conducive to Large-scale industrial production and application. Therefore, it is necessary to develop a hydrodeoxygenation catalyst with high activity, high selectivity, low cost and simple preparation method.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to develop a method for preparing a magnesium oxide-modified alumina-supported nickel-cobalt bimetallic catalyst.

Another object of the present invention is to provide the application of the above-mentioned magnesia-modified alumina-supported bimetallic nickel-cobalt catalyst in hydrodeoxygenation of lignin bio-oil.

The object of the present invention is achieved through the following solutions:

A method for preparing a magnesium oxide-modified aluminum oxide-supported bimetallic nickel-cobalt catalyst, comprising the following steps:

(1) mix magnesium salt, aluminum oxide and water, evaporate to dryness after stirring, then place in air and calcinate, obtain the aluminum oxide white powder modified by magnesium oxide;

(2) Soluble nickel salt and cobalt salt are formulated into a mixed solution, and the magnesium oxide-modified aluminum oxide white powder obtained in step (1) is added to the mixed solution, evaporated to dryness after fully stirring, then placed in air for calcination, and then placed Calcining in a mixed gas of hydrogen and argon can obtain a magnesium oxide-modified alumina-supported bimetallic nickel-cobalt catalyst.

The magnesium salt in step (1) is at least one of magnesium chloride, magnesium nitrate and magnesium sulfate, preferably magnesium nitrate hexahydrate; the aluminum oxide is α-Al ₂ O ₃ , β-Al ₂ O ₃ and γ- At least one of Al ₂ O ₃ , preferably γ-Al ₂ O ₃ .

The mass ratio of the magnesium salt to alumina in step (1) is (0.10-1.50): (0.20-2.00), preferably, the mass ratio of the magnesium salt to alumina is 0.51:1.00; the magnesium salt and The mass volume ratio of water is (0.20-0.70) g: 5-60 ml, preferably (0.30-0.60) g: 30 ml.

The stirring time in step (1) is 0.5～12h, preferably 2h; the evaporation temperature is 40～150°C, preferably 80°C; the temperature for calcination in air is 300～600°C, and the time is 1～ 6h, preferably, the calcination temperature is 450°C, and the time is 4h.

The concentrations of the soluble nickel salt and cobalt salt in the mixed solution in step (2) are (0.001-0.350) g/ml and (0.001-0.350) g/ml respectively, preferably 0.015 g/ml and 0.015 g/ml; The mass ratio of the magnesium oxide-modified alumina to the soluble nickel salt is (0.10-2.00): (0.10-0.60); preferably (0.50-1.20): (0.20-0.60), more preferably 0.90: (0.30- 0.60).

The stirring time in step (2) is 6-48h, preferably 24h; the evaporation temperature is 40-150°C, preferably 80°C; the calcination temperature in the air is 200-800°C, and the time is 1-8h , preferably, the calcination temperature is 400°C and the time is 4h; the calcination temperature in the hydrogen-argon mixed gas is 300-800°C and the time is 2h-8h. Preferably, the calcination temperature in the hydrogen-argon mixed gas is 550°C for 4 hours. More preferably, the heating program of the calcination in the hydrogen-argon mixed gas is to raise the temperature to 300-800° C. at a heating rate of 5° C./min.

The flow rate of the hydrogen-argon mixed gas during the calcining in the hydrogen-argon mixed gas in step (2) is 40-100 mL/min, preferably 80 mL/min.

A magnesia-modified aluminum oxide-supported bimetallic nickel-cobalt catalyst is prepared by the above method.

The application of the magnesium oxide-modified alumina-supported bimetallic nickel-cobalt catalyst in the hydrodeoxygenation reaction of lignin bio-oil.

A method for converting lignin bio-oil into cyclohexanol and derivatives thereof, specifically:

Using isopropanol as a solvent and the above-mentioned magnesia-modified alumina-supported bimetallic nickel-cobalt material as a catalyst, in the temperature range of 250-350 ° C, under the pressure of 1-4 MPa H ₂ , the lignin was reacted for 2-12 hours. Bio-oil conversion to cyclohexanol and its derivatives.

The mass volume ratio of the isopropanol, lignin bio-oil and catalyst is 20mL:(0.05-0.50)g:(0.06-2.50)g; preferably 20mL:0.10g:0.10g.

Preferably, the temperature is 300° C., and the reaction time is 5 h.

The invention uses transition metal nickel and cobalt as the active metal components of the catalyst, which is not only cheap and easy to obtain, but also significantly improves the activity of the catalyst for catalytic hydrodeoxygenation compared with single metal nickel-based catalysts. On the other hand, the use of magnesium oxide to modify the surface of alumina not only ensures that the crystal structure of alumina is not destroyed, but also changes the number of basic sites on the surface of alumina, which is beneficial to improve the quality of cyclohexanol and its derivatives. At the same time, the addition of magnesium oxide also strengthens the interaction between the active metal particles and the catalyst support, promotes the dispersion of nickel and cobalt particles, and improves the catalytic performance of the catalyst.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The preparation process of the catalyst is simple and easy to operate. Both the preparation of the catalyst support and the preparation of the catalyst adopt a wet impregnation method, and the preparation method is very simple.

(2) The catalyst prepared by the present invention uses bimetallic nickel-cobalt as the active component of the catalyst, and compared with the monometallic nickel-based catalyst, the catalytic activity and the selectivity to products are significantly improved.

(3) The catalyst prepared by the present invention adopts the strategy of magnesium oxide modification to regulate the number of basic sites of the catalyst, thereby achieving higher selectivity to cyclohexanol and its derivatives. At the same time, the addition of magnesium oxide also increases the interaction between nickel and cobalt particles and the carrier, promotes the dispersion of metal nickel and cobalt particles, and improves the catalytic performance and stability of the catalyst.

(4) The catalyst prepared by the present invention has excellent catalytic activity for the hydrodeoxygenation reaction of lignin bio-oil, and the yield of cyclohexanol and its derivatives can reach 65.6wt% at 300°C and 2MPa H ₂ . The technology of the invention greatly promotes the hydrodeoxygenation, quality improvement and modification of lignin bio-oil, and further promotes its industrial application.

Description of drawings

Fig. 1: the XRD spectrogram of catalyst prepared by embodiment 1 of the present invention, comparative example 1, comparative example 2;

Fig. 2: the scanning electron microscope picture of catalyst Ni-Co/MgO-Al ₂ O ₃ prepared in Example 1 of the present invention;

Fig. 3: Transmission electron micrograph (A) of catalyst Ni/Al ₂ O ₃ prepared in comparative example 1 of the present invention, transmission electron micrograph (B) of catalyst Ni-Co/Al ₂ O ₃ prepared in comparative example 2, embodiment 1 Transmission electron micrograph (C) of the prepared catalyst Ni-Co/ _MgO - _Al2O3 .

Figure 4: EDS-mapping spectrum of the catalyst Ni-Co/MgO-Al ₂ O ₃ prepared in Example 1 of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, comparative examples and drawings, but the embodiments of the present invention are not limited thereto.

The reagents used in the implementation cases and comparative cases can be purchased routinely from the market unless otherwise specified.

Implementation Case 1

Preparation of Ni-Co/MgO-Al ₂ O ₃ catalyst:

(1) Weigh 1.00g of γ-Al ₂ O ₃ and 0.51g of magnesium nitrate hexahydrate in a beaker filled with 30ml of deionized water at room temperature, stir for 2 hours at room temperature, evaporate the water to dryness in an oil bath at 80°C, and then Place it in an oven at 50°C for 24 hours.

(2) Grind the solid obtained after drying in (1) into powder, and then place it in a muffle furnace for calcination. The calcination procedure is: increase the temperature at a rate of 5°C/min to 450°C and keep it for 4 hours. After cooling to room temperature, the sample was taken out to obtain white solid MgO-Al ₂ O ₃ .

(3) Weigh 0.9g of the MgO-Al ₂ O ₃ solid obtained in (2), 0.45g of nickel nitrate hexahydrate, and 0.45g of cobalt nitrate hexahydrate in a beaker filled with 30ml of deionized water, and stir fully at room temperature for 24h , and then evaporated to dryness in an oil bath at 80°C, and dried in an oven at 50°C for 24 hours.

(4) Grind the dried solid in (3) into powder, and then place it in a muffle furnace for calcination. The calcination procedure is: increase the temperature to 400°C at a rate of 5°C/min and keep it for 4 hours. After cooling to room temperature, the sample was taken out to obtain a black solid.

(5) Put the black solid obtained in (4) into a quartz tube, use 8% hydrogen-argon mixed gas as the atmosphere, raise the temperature to 550°C at a heating rate of 5°C/min, keep it for 4h, and cool naturally to At room temperature, the sample was taken out to obtain a Ni-Co/MgO-Al ₂ O ₃ catalyst.

Fig. 2 is a scanning electron microscope image of Ni-Co/MgO-Al ₂ O ₃ catalyst. It can be observed from the figure that the surface of the catalyst presents an irregular granular morphology. Figure 3(C) is the transmission electron microscope image of the Ni-Co/MgO-Al ₂ O ₃ catalyst. According to the statistical calculation of the particle size distribution, the average size of nickel and cobalt particles is 17.21nm, compared to Ni-Co/ The size of nickel and cobalt particles (23.93nm) in the Al ₂ O ₃ catalyst decreases. The reason is that the addition of magnesium oxide enhances the interaction between the active metal particles and the support, and promotes the dispersion of the metal particles. Figure 4 is the EDS-Mapping diagram of the Ni-Co/MgO-Al ₂ O ₃ catalyst. It can be observed from the figure that nickel, cobalt and magnesium are highly dispersed in the catalyst.

Performance Testing

Add 0.10g of lignin bio-oil, 0.10g of Ni-Co/MgO-Al ₂ O ₃ catalyst, 20ml of isopropanol and 10μL of n-hexadecane into a batch stainless steel reactor, seal it well, fill it with hydrogen and discharge it, repeat The purpose of removing the air in the kettle was achieved three times, and finally, 2 MPa hydrogen was filled into the reaction kettle, and the reaction was carried out at 300°C for 5 hours. After the reaction was completed, the reaction solution was quickly cooled to room temperature by cooling water, and the reaction solution was taken out and filtered with a 0.22 μm organic filter membrane to obtain an organic phase containing the reaction product. Take 1 μL of the organic phase, use gas chromatography-mass spectrometry to conduct qualitative analysis of the reaction products, and use gas chromatography to perform quantitative calculations on the reaction products.

Implementation Case 2

The reaction steps and detection means are the same as those in Example 1, except that the reaction temperature is 260°C.

Implementation Case 3

The reaction steps and detection means are the same as those in Example 1, except that the reaction temperature is 280°C.

Implementation Case 4

The reaction steps and detection means are the same as those in Example 1, except that the reaction temperature is 320°C.

Implementation Case 5

The reaction steps and detection means are the same as those in Example 1, except that the reaction time is 3 hours.

Implementation Case 6

The reaction steps and detection means are the same as those in Example 1, except that the reaction time is 4 hours.

Implementation Case 7

The reaction steps and detection means are the same as those in Example 1, except that the reaction time is 6 hours.

Implementation Case 8

The reaction steps and detection means are the same as those in Example 1, except that the amount of catalyst used is 0.06g.

Implementation Case 9

The reaction steps and detection means are the same as those in Example 1, except that the amount of catalyst used is 0.08g.

Implementation Case 10

The reaction steps and detection means are the same as those in Example 1, except that the amount of catalyst used is 0.12 g.

Implementation Case 11

The reaction steps and detection means are the same as those in Example 1, except that the amount of catalyst used is 0.14g.

Comparative case 1

Preparation of Ni/Al ₂ O ₃ :

(1) Weigh 0.90g of γ-Al ₂ O ₃ and 0.45g of nickel nitrate hexahydrate into a beaker filled with 30ml of deionized water at room temperature, stir for 24 hours at room temperature, and then evaporate the water in an oil bath at 80°C , and then put the obtained solid into a 50°C oven to dry for 24h.

(2) Grind the dried solid in (1) and place it in a muffle furnace for calcination. The calcination procedure is: raise the temperature to 400°C at a rate of 5°C/min, keep it for 4h, and cool it down to room temperature naturally after the calcination, to obtain gray solid.

(3) Put the gray solid obtained in (2) into a quartz tube, use 8% hydrogen-argon gas mixture as the atmosphere, raise the temperature to 550°C at a rate of 5°C/min, keep it for 4h, and cool naturally to At room temperature, the sample was taken out to obtain a Ni/Al ₂ O ₃ catalyst.

Fig. 3(A) is a transmission electron microscope image of Ni/Al ₂ O ₃ catalyst. According to the statistical calculation of the nickel particle size in the catalyst, the average size of the active metallic nickel particle is 17.08nm, which is relatively small.

Performance Testing

Add 0.10g of lignin bio-oil, 0.10g of Ni/Al ₂ O ₃ catalyst, 20ml of isopropanol and 10μL of n-hexadecane into the intermittent stainless steel reactor, seal it well, fill it with hydrogen and then discharge it, repeat 3 times to achieve the elimination The purpose of the air in the kettle is to fill the reaction kettle with 2MPa hydrogen and react at 300°C for 5h. After the reaction was completed, the reaction solution was quickly cooled to room temperature by cooling water, and the reaction solution was taken out and filtered with a 0.22 μm organic filter membrane to obtain an organic phase containing the reaction product. Take 1 μL of the organic phase, use gas chromatography-mass spectrometry to conduct qualitative analysis of the reaction products, and use gas chromatography to perform quantitative calculations on the reaction products.

Comparative case 2

Preparation of Ni-Co/Al ₂ O ₃ :

(1) Weigh 0.90g of γ-Al ₂ O ₃ , 0.45g of nickel nitrate hexahydrate and 0.45g of cobalt nitrate hexahydrate at room temperature, add them into a beaker filled with 30ml of deionized water, stir at room temperature for 24 hours, and place in 80 The water was evaporated to dryness in an oil bath at ℃, and then the obtained solid was dried in an oven at 50℃ for 24 hours.

(2) Grind the dried solid in (1) and place it in a muffle furnace for calcination. The calcination procedure is: raise the temperature to 400°C at a rate of 5°C/min, keep it for 4h, and cool it down to room temperature naturally after the calcination, to obtain black solid.

(3) Put the black solid obtained in (2) into a quartz tube, use 8% hydrogen-argon gas mixture as the atmosphere, raise the temperature to 550°C at a rate of 5°C/min, keep it for 4h, and cool naturally to At room temperature, the sample was taken out to obtain a Ni-Co/Al ₂ O ₃ catalyst.

Fig. 3(B) is a transmission electron microscope image of Ni-Co/Al ₂ O ₃ catalyst. Through the statistical calculation of the particle size of nickel and cobalt in the catalyst, the average particle size is 23.93nm, which is larger than that of Ni/Al ₂ O ₃ active metal particles. The metal particles are more likely to agglomerate as the load increases. Second, there is a certain interaction between nickel and cobalt or the addition of cobalt changes the interaction between nickel and cobalt particles and the carrier, which in turn causes a change in particle size.

Performance Testing

Add 0.10g of lignin bio-oil, 0.10g of Ni-Co/Al ₂ O ₃ catalyst, 20ml of isopropanol and 10μL of n-hexadecane into a batch stainless steel reactor, seal it well, fill it with hydrogen and discharge it, repeat 3 times To achieve the purpose of removing the air in the kettle, finally fill the reaction kettle with 2MPa hydrogen and react at 300°C for 5h. After the reaction was completed, the reaction solution was quickly cooled to room temperature by cooling water, and the reaction solution was taken out and filtered with a 0.22 μm organic filter membrane to obtain an organic phase containing the reaction product. Take 1 μL of the organic phase, use gas chromatography-mass spectrometry to conduct qualitative analysis of the reaction products, and use gas chromatography to perform quantitative calculations on the reaction products.

Implementation effect description

The test results of comparative cases 1-2 and implementation cases 1-11 are shown in Table 1. From the results, it can be seen that the catalyst prepared by the present invention has excellent catalytic activity for the hydrodeoxygenation reaction of lignin bio-oil, and has The preparation raw materials are cheap and easy to obtain, and the preparation method is easy to operate. The lignin bio-oil is successfully converted into cyclohexanol and its derivatives, and the yield of cyclohexanol and its derivatives is at a relatively high level. By comparing the yields of cyclohexanol and its derivatives, the catalyst is preferably Ni-Co/MgO-Al ₂ O ₃ , the reaction temperature is preferably 300°C, the reaction time is preferably 5h, and the catalyst dosage is preferably 0.10g. With lignin bio-oil as the substrate, the catalyst Ni-Co/MgO-Al ₂ O ₃ dosage is preferably 0.10 g, and the yield of cyclohexanol and its derivatives reaches 65.6 wt%.

Table 1 Hydrodeoxygenation reaction data of lignin bio-oil

The structure of the prepared catalyst was characterized by X-ray diffraction (XRD), and the results are shown in Fig. 1 . Comparing the Ni-Co/Al ₂ O ₃ catalyst and the Ni-Co/MgO-Al ₂ O ₃ catalyst, it can be found that the peak height and peak width of the diffraction peak of Al ₂ O ₃ do not change after adding MgO, indicating that the addition of MgO does not It does not destroy the crystal structure of Al ₂ O ₃ , but acts as a modification. In addition, nickel and cobalt in Ni/Al ₂ O ₃ and Ni-Co/Al ₂ O ₃ are both zero-valent, and when magnesium oxide is added, the diffraction peaks of NiO and CoO appear, indicating that the addition of MgO makes some metals oxidize The metal particles are difficult to restore to the zero valence state because the addition of MgO enhances the interaction between the metal particles and the support. The morphology of the prepared catalyst was characterized by scanning electron microscopy, and the results are shown in Fig. 2 . It can be observed from the figure that the surface of the Ni-Co/MgO-Al ₂ O ₃ catalyst has a random granular morphology. Through the comparison of transmission electron microscope images (Figure 3) of Ni/Al ₂ O ₃ , Ni-Co/Al ₂ O ₃ , and Ni-Co/MgO-Al ₂ O ₃ catalysts, it can be found that the addition of cobalt makes nickel, cobalt The average particle size increases, on the one hand, because the addition of cobalt increases the total loading of active metals, and the particles are easier to agglomerate; on the other hand, there may be a certain interaction between nickel and cobalt, or the addition of cobalt changes the active metal particles. caused by the interaction with the carrier. After further adding magnesia, the average particle size of the active metal nickel and cobalt decreased again, indicating that the addition of magnesia was beneficial to enhance the interaction between metal particles and the support, and promote the dispersion of metal particles. From the EDS-Mapping diagram (Figure 4), it can be observed that Mg, Ni, and Co elements are highly dispersed in the Ni-Co/MgO-Al ₂ O ₃ catalyst.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. a preparation method of alumina-supported bimetallic nickel-cobalt catalyst modified by magnesium oxide, is characterized in that comprising the following steps: A method for preparing a magnesium oxide-modified aluminum oxide-supported bimetallic nickel-cobalt catalyst, comprising the following steps: (1) mix magnesium salt, aluminum oxide and water, evaporate to dryness after stirring, then place in air and calcinate, obtain the aluminum oxide white powder modified by magnesium oxide; (2) Soluble nickel salt and cobalt salt are formulated into a mixed solution, and the magnesium oxide-modified aluminum oxide white powder obtained in step (1) is added to the mixed solution, evaporated to dryness after fully stirring, then placed in air for calcination, and then placed Calcining in a mixed gas of hydrogen and argon can obtain a magnesium oxide-modified alumina-supported bimetallic nickel-cobalt catalyst. 2. The method according to claim 1, characterized in that: the soluble magnesium salt in step (1) is at least one of magnesium chloride, magnesium nitrate and magnesium sulfate; aluminum oxide is α-Al ₂ O ₃ , β- At least one of Al ₂ O ₃ and γ-Al ₂ O ₃ . 3. The method according to claim 1, characterized in that: the mass ratio of the magnesium salt and aluminum oxide in step (1) is (0.10～1.50): (0.20～2.00); the mass ratio of the magnesium salt and water The volume ratio is 0.20~0.70g:5~60ml. 4. The method according to claim 1, characterized in that: the stirring time in step (1) is 0.5 to 12 hours, the evaporation temperature is 40 to 150°C; the temperature for calcination in air is 300 to 600°C, the time is 1 to 6 hours. 5. The method according to claim 1, characterized in that: the concentration of the soluble nickel salt and cobalt salt in the mixed solution in step (2) is respectively (0.001～0.350) g/ml, (0.001～0.350) g /ml; the mass ratio of the magnesium oxide-modified aluminum oxide to the soluble nickel salt is (0.10-2.00): (0.10-0.60). 6. The method according to claim 1, characterized in that: the stirring time in step (2) is 6-48 hours; the evaporation temperature is 40-150°C; the calcination temperature in the air is 200-800°C , the time is 1-8h; the calcination temperature in the hydrogen-argon mixed gas is 300-800°C, and the time is 2h-8h; the heating program of the calcination in the hydrogen-argon mixed gas is a heating rate of 5°C/min to 300°C ~800°C. 7. The method according to claim 1, characterized in that: the flow rate of the hydrogen-argon mixed gas in the calcining in the hydrogen-argon mixed gas in step (2) is 40-100 mL/min. 8. A magnesium oxide-modified alumina-supported bimetallic nickel-cobalt catalyst, prepared by the method according to any one of claims 1-7. 9. The application of the alumina-supported bimetallic nickel-cobalt catalyst modified by magnesium oxide according to claim 8 in the hydrodeoxygenation reaction of lignin bio-oil. 10. A method for converting lignin bio-oil into cyclohexanol and derivatives thereof, characterized in that: Using isopropanol as a solvent, using the magnesia-modified alumina-supported bimetallic nickel-cobalt as described in claim 8 as a catalyst, reacting for 2 to 12 hours at a temperature range of 250 to 350° C. under a pressure of 1 to 4 MPa H ₂ Conversion of lignin bio-oil to cyclohexanol and its derivatives.

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