Preparation of a highly active nickel-based catalyst and its application in the hydrodeoxygenation of guaiacol

Abstract

The present invention provides a preparation method of a highly active nickel-based catalyst and its application in the hydrodeoxygenation of guaiacol. The catalyst is prepared by high-temperature calcination and reduction treatment using nickel-aluminum layered double metal hydroxide with precisely controllable structure as the precursor. The molar ratio of Ni<supgt;2+< / supgt; to Al<supgt;3+< / supgt> used for preparing the nickel-aluminum layered double metal hydroxide is 2 / 1 to 4 / 1, the calcination temperature is 400 to 500 °C, and the reduction temperature is 400 to 500 °C. The hydrodeoxygenation reaction of guaiacol is carried out in a batch high-pressure reactor, the reaction temperature is 160 to 240 °C, and the reaction time is 4 to 8 h. The highly active nickel-based catalyst described in the present invention has the advantages of uniform dispersion of the metal phase, precisely adjustable catalytic active sites, high specific surface area, and strong metal-support interaction, etc., and exhibits excellent catalytic performance in the hydrodeoxygenation reaction of guaiacol, and can convert guaiacol into cyclohexane with high selectivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical catalytic materials, and particularly relates to the preparation of a highly active nickel-based catalyst and its application in the hydrodeoxygenation reaction of guaiacol. Background Art

[0002] Guaiacol is the most commonly used lignin model compound, and through the hydrodeoxygenation reaction, it can be selectively converted into cyclohexane and alkylphenol compounds. Early research work on the catalytic conversion of guaiacol mainly focused on traditional NiMoS2, CoMoS2 catalysts and supported noble metal catalysts. However, these catalysts need to exhibit excellent hydrodeoxygenation performance under high hydrogen pressure and high temperature reaction conditions, and have a strong tendency for benzene ring hydrogenation, resulting in low selectivity of the target product.

[0003] Under appropriate reaction conditions, supported nickel-based catalysts have catalytic activity comparable to noble metal catalysts and are widely used in hydrodeoxygenation reactions. The conventional preparation method of supported nickel-based catalysts is to co-precipitate their salts with other metal salts, or impregnate a porous carrier with their salt solution, and then obtain the catalyst sample through high-temperature calcination and reduction treatment. However, the active component Ni of the supported nickel-based catalyst prepared by the conventional co-precipitation method has poor dispersion, and there are phenomena of structural collapse and inactivation of the active component during the hydrothermal reaction process. Research shows that the geometric structure and electronic structure of the active sites of supported metal catalysts directly affect the ability of the catalyst surface to adsorb hydrogen, thereby determining the activity and selectivity of the catalyst. Improving the dispersion of the active components on the surface of supported nickel-based catalysts and finely regulating their surface active sites can effectively improve their catalytic activity and also significantly improve the hydrothermal stability of supported nickel-based catalysts. Metal oxides derived from layered double metal hydroxides often have the unique properties of high dispersion and high stability, and have great application potential in the preparation of supported metal catalysts.

[0004] Based on this, it is of great significance to develop a supported nickel-based catalyst with uniformly dispersed metal phase and high catalytic activity using nickel-aluminum layered double metal hydroxide with precisely controllable structure as the precursor for the selective hydrodeoxygenation reaction of guaiacol. Summary of the Invention

[0005] The present invention aims at the problems of low catalyst activity and selectivity in the current hydrodeoxygenation reaction of guaiacol, poor dispersion of active components and poor hydrothermal stability in the catalyst preparation process, and provides a highly active nickel-based catalyst that can be used in the hydrodeoxygenation reaction of guaiacol. This catalyst is obtained by using nickel-aluminum layered double metal hydroxide with precisely controllable structure as the precursor and undergoing high-temperature calcination and reduction treatment.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A preparation method of a highly active nickel-based catalyst, and the method is carried out according to the following steps:

[0008] (1) Weigh nickel nitrate hexahydrate, aluminum nitrate nonahydrate and 250 mL of distilled water in a certain molar ratio, add them to a 500 mL three-necked flask, stir to dissolve all of them, then add a certain amount of urea, react at 105 °C for 12 h, age at 95 °C for 24 h, filter and wash after cooling to room temperature to obtain the filter residue, and vacuum dry at 80 °C overnight to obtain nickel-aluminum layered double metal hydroxide, denoted as NiAl-LDH;

[0009] (2) Place the nickel-aluminum layered double metal hydroxide obtained in step (1) in a muffle furnace, calcine for 6 h in an air atmosphere, and the calcination temperature is 400 - 500 °C to obtain nickel-aluminum layered double metal oxide, denoted as NiAl-LDO;

[0010] (3) Then place the nickel-aluminum layered double metal oxide obtained in step (2) in a tubular furnace, reduce it in a hydrogen atmosphere for 6 h, and the reduction temperature is 400 - 500 °C to obtain a highly active nickel-based catalyst, denoted as Ni / Al2O3-LDH.

[0011] As a limitation of the present invention, in step (1) of the present invention, the molar ratio of Ni 2+ and Al 3+ in the nickel-aluminum layered double metal hydroxide is 2 / 1 - 4 / 1; the amount of urea used to prepare the nickel-aluminum layered double metal hydroxide is 3 times the total molar number of charges carried by cations Ni 2+ and Al 3+ ;

[0012] As a further limitation of the present invention, the calcination temperature in step (2) of the present invention is 450 °C, and the reduction temperature in step (3) is 450 °C.

[0013] Apply the above-prepared highly active nickel-based catalyst in the guaiacol hydrodeoxygenation reaction according to the following method:

[0014] (1) Add a certain amount of guaiacol, highly active nickel-based catalyst and n-hexane to a 100 mL batch high-pressure reactor;

[0015] (2) Replace the gas with nitrogen and hydrogen respectively, then fill in hydrogen with an initial pressure of 3 MPa, set a certain stirring speed, set the reaction temperature to 160 °C - 240 °C, the reaction time is 4 - 8 h, quickly cool the reactor to room temperature after the reaction ends, filter to obtain the reaction solution, and analyze the product by gas chromatography.

[0016] As a limitation on the application of the above-mentioned highly active nickel-based catalyst, the mass ratio of guaiacol to the catalyst in the present invention is 2:1 to 8:1.

[0017] After adopting the above technical solution, the present invention has achieved the following beneficial effects:

[0018] 1. The present invention uses nickel-aluminum layered double hydroxide as a precursor to prepare a highly active nickel-based catalyst Ni / Al2O3 with uniformly dispersed metal phases, precisely adjustable catalytic active sites, high specific surface area, and strong metal-support interaction.

[0019] The principle of the high catalytic activity of the catalyst is mainly because, generally speaking, the chemical general formula of layered double hydroxide is [M 1-x 2+ M x 3+ (OH)2] x+ [A x / n n- .mH2O, where M 2+ and M 3+ represent divalent and trivalent lamellar metal cations respectively, and enter the interlayer through the electrostatic interaction of charges with the interlayer anion A n- . Layered double hydroxide has tunability. By adjusting the types of introduced metal cations and the ratio of divalent and trivalent metal cations, different active metal elements can be introduced into the layer structure; the particle size and distribution of active metals can also be controlled by changing the synthesis method and synthesis conditions; restricted by the lattice localization effect, metal ions are highly dispersed with each other on the layered double hydroxide lamellae. After high-temperature calcination and reduction treatment, other metal components except active metals can be transformed into corresponding oxides to play the role of co-catalysts and isolation agents, thereby obtaining a metal catalyst with highly dispersed metal active sites.

[0020] 2. When this catalyst is applied to the selective hydrodeoxygenation reaction of guaiacol, compared with the prior art, under the same reaction conditions, the conversion rate of guaiacol can reach 100%, and the selectivity of cyclohexane can reach 95%, significantly improving the yield of cyclohexane; and when the conversion rate of guaiacol and the selectivity of cyclohexane are comparable to those of the prior art, the reaction temperature is lower and the reaction conditions are milder. Therefore, the highly active nickel-based catalyst described in the present invention shows excellent catalytic performance for the hydrodeoxygenation reaction of guaiacol. Description of the Drawings

[0021] Figure 1 ​XRD pattern of the highly dispersed Ni / Al2O3-LDH catalyst obtained in Example 2; it can be seen from the figure that NiAl-LDH shows a relatively complete and pure hydrotalcite-like crystal phase, with the molecular formula Ni2Al(CO3)2(OH)3 (PDF#48-0594), which is a hydrotalcite-like material with CO3 as the interlayer anion. The high and sharp diffraction peaks at lower 2θ values indicate the obvious layered structure; NiAl-LDO is mainly composed of NiO phase (PDF#65-6920), and no diffraction peak of Al2O3 is found; in Ni / Al2O3-LDH, Ni 2- is a hydrotalcite-like material with CO3 as the interlayer anion. The high and sharp diffraction peaks at lower 2θ values indicate the obvious layered structure; NiAl-LDO is mainly composed of NiO phase (PDF#65-6920), and no diffraction peak of Al2O3 is found; in Ni / Al2O3-LDH, Ni 2+ is reduced to pure Ni 0 phase (PDF#65-0380), and no diffraction peak of Al2O3 is found. Detailed implementation mode

[0022] The present invention will be further described with reference to the following examples. It should be understood that these examples are only for illustrative purposes and should not be construed as limiting the implementation of the present invention.

[0023] Example 1

[0024] Weigh 58.158 g of nickel nitrate hexahydrate, 37.513 g of aluminum nitrate nonahydrate and 250 mL of water, add them to a 500 mL three-necked flask, stir to dissolve all of them, then add 126.126 g of urea, heat the mixture to 105 °C and react for 12 h after mixing evenly, stop stirring and cool to 95 °C for aging for 24 h, filter and wash after cooling to room temperature to obtain the filter residue, vacuum dry at 80 °C overnight, then place it in a muffle furnace and calcine at 400 °C for 6 h in an air atmosphere, place the obtained solid in a tubular furnace and reduce it at 400 °C for 6 h in a hydrogen atmosphere to obtain a Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with Ni / Al ratio of 2 / 1.

[0025] Example 2

[0026] Weigh 58.158 g of nickel nitrate hexahydrate, 37.513 g of aluminum nitrate nonahydrate and 250 mL of water, add them to a 500 mL three-necked flask, stir to dissolve all of them, then add 126.126 g of urea, heat the mixture to 105 °C and react for 12 h after mixing evenly, stop stirring and cool to 95 °C for aging for 24 h, filter and wash after cooling to room temperature to obtain the filter residue, vacuum dry at 80 °C overnight, then place it in a muffle furnace and calcine at 450 °C for 6 h in an air atmosphere, place the obtained solid in a tubular furnace and reduce it at 450 °C for 6 h in a hydrogen atmosphere to obtain a Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with Ni / Al ratio of 2 / 1.

[0027] Example 3

[0028] Weigh 58.158 g of nickel nitrate hexahydrate, 37.513 g of aluminum nitrate nonahydrate and 250 mL of water, add them to a 500 mL three-necked flask. After stirring to dissolve all of them, add 126.126 g of urea. After mixing evenly, heat to 105 °C and react for 12 h. Stop stirring and cool to 95 °C for aging for 24 h. After cooling to room temperature, filter and wash to obtain the filter residue. After vacuum drying at 80 °C overnight, place it in a muffle furnace and calcine at 500 °C in an air atmosphere for 6 h. Place the obtained solid in a tubular furnace and reduce it at 500 °C in a hydrogen atmosphere for 6 h to obtain Ni 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a Ni / Al ratio of 2 / 1.

[0029] Example 4

[0030] Weigh 65.428 g of nickel nitrate hexahydrate, 28.135 g of aluminum nitrate nonahydrate and 250 mL of water, add them to a 500 mL three-necked flask. After stirring to dissolve all of them, add 121.621 g of urea. After mixing evenly, heat to 105 °C and react for 12 h. Stop stirring and cool to 95 °C for aging for 24 h. After cooling to room temperature, filter and wash to obtain the filter residue. After vacuum drying at 80 °C overnight, place it in a muffle furnace and calcine at 450 °C in an air atmosphere for 6 h. Place the obtained solid in a tubular furnace and reduce it at 450 °C in a hydrogen atmosphere for 6 h to obtain Ni 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a Ni / Al ratio of 3 / 1.

[0031] Example 5

[0032] Weigh 69.790 g of nickel nitrate hexahydrate, 22.508 g of aluminum nitrate nonahydrate and 250 mL of water, add them to a 500 mL three-necked flask. After stirring to dissolve all of them, add 118.919 g of urea. After mixing evenly, heat to 105 °C and react for 12 h. Stop stirring and cool to 95 °C for aging for 24 h. After cooling to room temperature, filter and wash to obtain the filter residue. After vacuum drying at 80 °C overnight, place it in a muffle furnace and calcine at 450 °C in an air atmosphere for 6 h. Place the obtained solid in a tubular furnace and reduce it at 450 °C in a hydrogen atmosphere for 6 h to obtain Ni 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a Ni / Al ratio of 4 / 1.

[0033] Example 6

[0034] Apply the Ni / Al2O3-LDH catalyst with a Ni / Al ratio of 2 / 1 prepared in Example 2 to the reaction. 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a Ni / Al ratio of 2 / 1.

[0035] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 160 °C, and the reaction time to 6 h. Quickly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 80.2%, and the selectivity of cyclohexane is 67.6%.

[0036] Example 7

[0037] Apply the Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 prepared in Example 2 to the reaction.

[0038] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 180 °C, and the reaction time to 6 h. Quickly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 91.4%, and the selectivity of cyclohexane is 79.9%.

[0039] Example 8

[0040] Apply the Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 prepared in Example 2 to the reaction.

[0041] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 200 °C, and the reaction time to 6 h. Quickly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 95.2%.

[0042] Example 9

[0043] Apply the Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 prepared in Example 2 to the reaction.

[0044] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n - hexane and add them into a 100 - mL batch high - pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa is filled. Set the stirring speed to 600 rpm, set the reaction temperature to 220 °C, and the reaction time to 6 h. Cool the reactor rapidly to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 86.5%.

[0045] Example 10

[0046] Add the Ni 2+ / Al 3+ Ni / Al₂O₃ - LDH catalyst with a ratio of 2 / 1 prepared in Example 2 to the reaction.

[0047] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n - hexane and add them into a 100 - mL batch high - pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa is filled. Set the stirring speed to 600 rpm, set the reaction temperature to 240 °C, and the reaction time to 6 h. Cool the reactor rapidly to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 81.4%.

[0048] Example 11

[0049] Add the Ni 2+ / Al 3+ Ni / Al₂O₃ - LDH catalyst with a ratio of 2 / 1 prepared in Example 1 to the reaction.

[0050] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n - hexane and add them into a 100 - mL batch high - pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa is filled. Set the stirring speed to 600 rpm, set the reaction temperature to 200 °C, and the reaction time to 6 h. Cool the reactor rapidly to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 73.8%.

[0051] Example 12

[0052] Add the Ni 2+ / Al 3+ Ni / Al₂O₃ - LDH catalyst with a ratio of 2 / 1 prepared in Example 3 to the reaction.

[0053] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 200 °C, and the reaction time to 6 h. Rapidly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 58.3%.

[0054] Example 13

[0055] Add the Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 prepared in Example 4 into the reaction.

[0056] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 200 °C, and the reaction time to 6 h. Rapidly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 100%, and the selectivity of cyclohexane is 87.5%.

[0057] Example 14

[0058] Add the Ni 2+ / Al 3+ Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 prepared in Example 5 into the reaction.

[0059] Weigh 0.8 g of guaiacol, 0.2 g of catalyst and 40 mL of n-hexane and add them into a 100 mL batch high-pressure reactor. Replace the gas with nitrogen and hydrogen three times respectively, then fill with hydrogen with an initial pressure of 3 MPa. Set the stirring speed to 600 rpm, set the reaction temperature to 200 °C, and the reaction time to 6 h. Rapidly cool the reactor to room temperature, filter to obtain the reaction solution, and quantitatively analyze the conversion rate of guaiacol and the selectivity of cyclohexane by gas chromatography. In this example, the conversion rate of guaiacol is 96.5%, and the selectivity of cyclohexane is 83.7%.

[0060] Example 15

[0061] Add the Ni 2+ / Al 3+The Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 was applied to the reaction.

[0062] 0.8 g of guaiacol, 0.2 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch autoclave. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 4 h. The autoclave was rapidly cooled to room temperature, and the reaction solution was filtered. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this example, the conversion rate of guaiacol was 81.6%, and the selectivity of cyclohexane was 82.1%.

[0063] Example 16

[0064] The Ni 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 was applied to the reaction.

[0065] 0.8 g of guaiacol, 0.2 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch autoclave. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 8 h. The autoclave was rapidly cooled to room temperature, and the reaction solution was filtered. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this example, the conversion rate of guaiacol was 100%, and the selectivity of cyclohexane was 79.6%.

[0066] Example 17

[0067] The Ni 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 was applied to the reaction.

[0068] 0.8 g of guaiacol, 0.1 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch autoclave. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 6 h. The autoclave was rapidly cooled to room temperature, and the reaction solution was filtered. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this example, the conversion rate of guaiacol was 100%, and the selectivity of cyclohexane was 80.6%.

[0069] Example 18

[0070] The Ni 2+ / Al3+ The Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 was applied to the reaction.

[0071] 0.8 g of guaiacol, 0.3 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch high-pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 6 h. The reactor was quickly cooled to room temperature, and the reaction solution was obtained by filtration. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this example, the conversion rate of guaiacol was 100%, and the selectivity of cyclohexane was 79.9%.

[0072] Example 19

[0073] The Ni prepared in Example 2 2+ / Al 3+ The Ni / Al2O3-LDH catalyst with a ratio of 2 / 1 was applied to the reaction.

[0074] 0.8 g of guaiacol, 0.4 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch high-pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 6 h. The reactor was quickly cooled to room temperature, and the reaction solution was obtained by filtration. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this example, the conversion rate of guaiacol was 100%, and the selectivity of cyclohexane was 70.4%.

[0075] Comparative Example 1

[0076] NiAl-LDH with a ratio of 2 / 1 prepared by the traditional co-precipitation hydrothermal method was used as the precursor to prepare a hydrotalcite-based Ni / Al2O3 catalyst, which was applied to the reaction. 2+ / Al 3+ The NiAl-LDH with a ratio of 2 / 1 prepared by the traditional co-precipitation hydrothermal method was used as the precursor to prepare a hydrotalcite-based Ni / Al2O3 catalyst, which was applied to the reaction.

[0077] 0.8 g of guaiacol, 0.2 g of the catalyst, and 40 mL of n-hexane were weighed and added to a 100 mL batch high-pressure reactor. After displacing the gas with nitrogen and hydrogen three times respectively, hydrogen with an initial pressure of 3 MPa was charged. The stirring speed was set at 600 rpm, the reaction temperature was set at 200 °C, and the reaction time was 6 h. The reactor was quickly cooled to room temperature, and the reaction solution was obtained by filtration. The conversion rate of guaiacol and the selectivity of cyclohexane were quantitatively analyzed by gas chromatography. In this comparative example, the conversion rate of guaiacol was 100%, and the selectivity of cyclohexane was 56.5%.

[0078] Table 1 High-activity Ni / Al2O3 catalysts obtained by different preparation methods

[0079] Example <![CDATA[Ni 2+ / Al 3+ > Roasting temperature Reduction temperature Example 1 2 / 1 400 400 Example 2 2 / 1 450 450 Example 3 2 / 1 500 500 Example 4 3 / 1 450 450 Example 5 4 / 1 450 450

[0080] Table 2 Comparison of catalytic activities between the examples and the comparative examples

[0081]

[0082] As can be seen from Table 1 and Table 2, when the catalyst obtained in the present invention is applied to the hydrodeoxygenation reaction of guaiacol, good catalytic performance is achieved compared with the catalysts obtained by the prior art. Among them, the molar ratio of Ni 2+ and Al 3+ used in the nickel-aluminum layered double metal hydroxide, the calcination temperature and the reduction temperature all have great influences on the catalytic performance of the obtained highly dispersed Ni / Al2O3-LDH catalyst. The conversion rate of guaiacol and the selectivity of cyclohexane have been significantly improved compared with the prior art. The highest conversion rate of guaiacol can reach 100%, and the highest selectivity of cyclohexane can reach 95.2%. Moreover, when the catalytic activities are the same, the catalyst preparation conditions of the present invention are mild and the cost is low.

[0083] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. Application of a highly active nickel-based catalyst in hydrodeoxygenation of guaiacol, characterized in that The application is carried out according to the following steps: (1) Add a certain amount of guaiacol, highly active nickel-based catalyst and n-hexane into a batch high-pressure reactor. After replacing the gas with nitrogen and hydrogen respectively, fill it with hydrogen with an initial pressure of 3 MPa; The highly active nickel-based catalyst described above is prepared according to the following method: (A) Weigh a certain molar ratio of nickel nitrate hexahydrate, aluminum nitrate nonahydrate and 250 mL of distilled water, add them to a 500 mL three-necked flask, stir to dissolve all of them, then add a certain amount of urea, react at 105 °C for 12 h, age at 95 °C for 24 h, filter and wash the residue after cooling to room temperature, and vacuum dry at 80 °C overnight to obtain nickel-aluminum layered double hydroxide, denoted as NiAl-LDH. In the nickel-aluminum layered double hydroxide, the molar ratio of Ni 2+ and Al 3+ is 2:1 to 4:1, and the amount of urea used is 3 times the total molar number of charges carried by the cations Ni 2+ and Al 3+ ; (B) Place the nickel-aluminum layered double hydroxide obtained in step (A) in a muffle furnace and calcine it in an air atmosphere for 6 h at a calcination temperature of 400-500 °C to obtain nickel-aluminum layered double metal oxide, denoted as NiAl-LDO; (C) Then place the nickel-aluminum layered double metal oxide obtained in step (B) in a tubular furnace and reduce it in a hydrogen atmosphere for 6 h at a reduction temperature of 400-500 °C to obtain the highly active nickel-based catalyst, denoted as Ni / Al2O3-LDH; (2) Under the stirring state, set the reaction temperature to 160 °C - 240 °C and the reaction time to 4 - 8 h. After the reaction is completed, quickly cool the reactor to room temperature, filter to obtain the reaction solution, and analyze the product by gas chromatography.

2. Use of a highly active nickel-based catalyst according to claim 1 in the hydrodeoxygenation of guaiacol, characterized in that In step (1), the mass ratio of the guaiacol to the highly active nickel catalyst is 2:1 - 8:1.

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