Preparation method and application of catalyst and preparation method of valerolactam

Abstract

The invention relates to the technical field of preparation of cyclopentanone through furfural hydrogenation, and discloses a preparation method and application of a catalyst and a preparation method of valerolactam. The preparation method comprises the following steps: (1) adding an active component precursor into an alkaline solution to obtain a mixed solution; the active component precursor is selected from one or more of a Pd-containing compound, a Pt-containing compound and a Ru-containing compound; the alkaline solution is selected from one or more of ammonia water, an AMP buffer solution and a triethylamine aqueous solution; (2) adding dopamine into the mixed solution, and carrying out oxidation-reduction reaction to obtain a solid material; (3) roasting the solid material at low temperature to obtain the catalyst; the roasting temperature of the low-temperature roasting is 200-550 DEG C. According to the preparation method provided by the invention, the furfural hydrogenation catalyst with good catalytic activity and high cyclopentanone yield can be prepared under the coordination action of the specific alkaline solution and low-temperature roasting.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing cyclopentanone by furfural hydrogenation, and specifically relates to a preparation method of a catalyst and its application, and a preparation method of valerolactam. Background Art

[0002] Valerolactam is a white crystalline mass with a low melting point, having good solubility, and can dissolve in solvents such as water, ethanol, ether, and acetone. It is mainly used in the production of polyamide, engineering plastics, and films, and has wide applications in fields such as textiles, packaging, electronics, automobiles, and machinery.

[0003] Currently, industrially, valerolactam is mainly obtained by the oximation reaction of cyclopentanone combined with the Beckmann rearrangement process using cyclopentanone as a raw material. However, cyclopentanone is expensive, and the method of directly using cyclopentanone to synthesize valerolactam poses challenges in terms of economy, which limits the technological development of large-scale industrial production of valerolactam. Therefore, developing a cost-effective and high-yield cyclopentanone synthesis method is crucial for meeting the demand for valerolactam in industrial production.

[0004] Currently, the synthesis methods of cyclopentanone mainly include adipic acid decarboxylation cyclization method, cyclopentene oxidation method, and furfural hydrogenation method. Among them, the adipic acid decarboxylation cyclization method is the main method for industrial production of cyclopentanone. However, this method has problems such as low theoretical yield (57.5%), poor atom economy, and relatively harsh reaction conditions. Although the cyclopentene oxidation method has the advantages of high cyclopentanone yield and environmental friendliness, this method has harsh reaction conditions, uses homogeneous catalysis, and the separation of the catalyst is difficult, and the process is not yet mature, which to a certain extent limits its industrial application.

[0005] Compared with traditional synthesis routes, the process of hydrogenating biomass derivatives (such as furfural, etc.) to produce cyclopentanone is considered a sustainable and green process because its raw materials are renewable and the process is environmentally friendly. However, there is currently a lack of a catalyst system with excellent performance, which has become the key bottleneck restricting the large-scale application of this process. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems in the prior art such as poor catalytic activity, low cyclopentanone yield, and poor stability of the catalyst used in the hydrogenation of furfural to prepare cyclopentanone, and to provide a preparation method of a catalyst and its application, and a preparation method of valerolactam.

[0007] To achieve the above purpose, the first aspect of the present invention provides a preparation method of a catalyst, wherein the preparation method includes the following steps:

[0008] (1) Add the active component precursor to an alkaline solution to obtain a mixed solution; wherein, the active component precursor is selected from one or more of Pd-containing compounds, Pt-containing compounds, and Ru-containing compounds; the alkaline solution is selected from one or more of ammonia water, AMP buffer solution, and triethylamine aqueous solution;

[0009] (2) Add dopamine to the mixed solution to carry out a redox reaction to obtain a solid material;

[0010] (3) Calcinate the solid material at a low temperature to obtain a catalyst; wherein, the calcination temperature of the low-temperature calcination is 200 - 550 °C.

[0011] The second aspect of the present invention provides an application of the catalyst prepared by the method described in the first aspect of the present invention in the hydrogenation of furfural to prepare cyclopentanone.

[0012] The third aspect of the present invention provides a method for preparing valerolactam, wherein the method includes the following steps:

[0013] (A) Contact furfural, hydrogen, and the reduced catalyst in water to carry out a hydrogenation reaction to obtain cyclopentanone; wherein, the catalyst is the catalyst described in the first aspect of the present invention;

[0014] (B) Contact the cyclopentanone, ammonia, hydrogen peroxide, and titanium silicalite in tert-butanol to carry out an oximation reaction to obtain cyclopentanone oxime;

[0015] (C) Contact the cyclopentanone oxime with fuming sulfuric acid to carry out a Beckmann rearrangement reaction to obtain a rearrangement liquid;

[0016] (D) Contact the rearrangement liquid with ammonia and demineralized water to carry out a neutralization reaction to obtain valerolactam.

[0017] Through the above technical solutions, the beneficial technical effects achieved by the present invention are as follows:

[0018] (1) For the catalyst preparation method provided by the present invention, the reaction between the active component precursor and dopamine is carried out in a specific alkaline solution, and the solid material is calcined at a low temperature, which can enhance the interaction between the carrier and the active component, regulate the distribution of the active component, and thus can significantly improve the catalytic reaction activity and stability of the catalyst in the furfural hydrogenation reaction;

[0019] (2) The catalyst preparation method provided by the present invention has simple operation, reliable method, strong repeatability, good stability, and highly dispersed active metals, which is conducive to large-scale production and use;

[0020] (3) The preparation method of the catalyst provided by the present invention has excellent catalytic activity in the hydrogenation of furfural to prepare cyclopentanone. The furfural conversion rate is above 95%, and the yield of cyclopentanone is above 70%, which can effectively meet the application requirements of valerolactam production;

[0021] (4) The preparation method of valerolactam provided by the present invention can significantly reduce the production cost of valerolactam, and also has environmental friendliness, with less three-waste emissions and reduced environmental pollution. In addition, this method has a simple operation process and mild reaction conditions, and is suitable for industrial-scale application and promotion. Detailed implementation mode

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] Among them, in the present invention, unless otherwise specified, all operations related to solution preparation preferably use mechanical stirring or magnetic stirring, and the stirring speed is 300-600 revolutions per minute.

[0024] The first aspect of the present invention provides a preparation method of a catalyst. Among them, the preparation method includes the following steps:

[0025] (1) Add the active component precursor to the alkaline solution to obtain a mixed solution; among them, the active component precursor is selected from one or more of Pd-containing compounds, Pt-containing compounds, and Ru-containing compounds; the alkaline solution is selected from one or more of ammonia water, AMP buffer solution, and triethylamine aqueous solution;

[0026] (2) Add dopamine to the mixed solution to carry out a redox reaction to obtain a solid material;

[0027] (3) Carry out low-temperature calcination on the solid material to obtain a catalyst; among them, the calcination temperature of the low-temperature calcination is 200-550 °C.

[0028] Among them, in the present invention, the inventors of the present invention have found through research that the reaction of the active component precursor and dopamine is carried out in a specific alkaline solution, and the solid material is calcined at a low temperature. The coordinated action of the specific weak base environment and low-temperature calcination can prepare a furfural hydrogenation catalyst with good catalytic activity and high cyclopentanone yield.

[0029] In the alkaline solution defined in the present invention, the redox potential of the alkali and the metal ions in the active component precursor are better matched, which can promote the occurrence of redox reactions, stabilize the coordination between the metal ions and the carrier, avoid the active component precursor from forming precipitation in an alkaline environment as much as possible, and increase the loading amount of the active component on the carrier, thereby solving the problem of the reduction in the number of catalyst active sites that is easily caused by low-temperature roasting. Low-temperature roasting can further enhance the interaction between the active component and the carrier, help maintain the stability of the catalyst, and promote the dispersion of active metal particles from the active component precursor to prevent agglomeration, thereby significantly improving the catalytic reaction activity of the catalyst.

[0030] In step (1):

[0031] In a preferred embodiment of the present invention, the Pd-containing compound is selected from one or more of chloroplatinic acid, chloroplatinous acid, platinum nitrate, bis(ethylenediamine)platinum acetate, and platinum acetate acetonate; the Pd-containing compound is selected from one or more of ammonium hexachloropalladate, palladium nitrate, palladium acetate, palladium acetylacetonate, and dinitrosodiamminepalladium; the Ru-containing compound is selected from one or more of ruthenium trichloride, ruthenium nitrosyl nitrate, ruthenium acetate, ruthenium acetate, and ruthenium acetylacetonate.

[0032] In a preferred embodiment of the present invention, in order to further improve the uniformity of the mixed solution, the active component precursor is preferably added in the form of an active component precursor aqueous solution, for example, slowly added dropwise. The molar concentration of the active component precursor in the active component precursor aqueous solution is 0.01-0.12 mol / L, preferably 0.02-0.1 mol / L.

[0033] In a preferred embodiment of the present invention, the alkaline solution is aqueous ammonia.

[0034] Among them, in the present invention, the inventors have found through research that the alkaline solution contains N elements, and nitrogen atoms can be introduced into the carrier of the catalyst. The nitrogen atoms help to strengthen the interaction between the active component and the carrier formed by dopamine, increase the electron density on the surface of the active metal, and regulate the adsorption behavior of reactants and products, thereby further improving the catalytic activity of the catalyst. When the alkaline solution is ammonia water, the catalytic activity of the catalyst is better.

[0035] In a preferred embodiment of the present invention, the pH value of the alkaline solution is 8-10, for example, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, and any number therebetween, preferably 8.5-9.

[0036] In a preferred embodiment of the present invention, the pH of the alkaline solution is adjusted by adding water and / or an alcohol solvent; wherein, the alcohol solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

[0037] Wherein, in the present invention, the inventors have found through research that adding a small amount of alcohol solvent to a weak base solution can further improve the selectivity of the prepared catalyst and contribute to increasing the yield of cyclopentanone.

[0038] In a preferred embodiment of the present invention, the pH of the alkaline solution is adjusted by adding a mixed solution comprising water and an alcohol solvent; wherein, in the water and alcohol solvent mixed solution, the volume ratio of water to the alcohol solvent is 1-5:1, preferably 2-3:1.

[0039] In a preferred embodiment of the present invention, based on 1 mmol of the active component precursor, the amount of the alkaline solution is 0.2-4 L, preferably 0.5-2 L.

[0040] In step (2):

[0041] In a preferred embodiment of the present invention, based on 1 g of the dopamine, the amount of the mixed solution is 160-480 mL, preferably 240-320 mL.

[0042] Wherein, in the present invention, dopamine is used to generate the carbon support in the catalyst, and the active component precursor is converted into the active component in the catalyst. The amounts of dopamine and the mixed solution are such that in the prepared catalyst, based on the total mass of the furfural hydrogenation catalyst, the content of the support is 75-99.7 wt%, preferably 90-97 wt%; and the content of the active component is 0.3-25 wt%, preferably 4-10 wt%. Wherein, in the present invention, the content of the active component is based on the content of the metal element.

[0043] In a preferred embodiment of the present invention, in order to further improve the uniformity of the redox reaction, dopamine is preferably added in the form of an aqueous dopamine solution, for example, slowly dropped. Wherein, in the aqueous dopamine solution, the molar concentration of dopamine is 0.1-1 mol / L, preferably 0.3-0.8 mol / L.

[0044] In a preferred embodiment of the present invention, the operating conditions of the redox reaction include: the reaction temperature of the redox reaction is room temperature, and the reaction time is 10-70 h, preferably 30-50 h. Wherein, the present invention does not make special limitations on room temperature. For example, it can be 10-35 °C.

[0045] In step (3):

[0046] In a preferred embodiment of the present invention, before the low-temperature calcination of the solid material, the solid material is washed and dried. For example, it is washed with deionized water and dried at 60-100 °C for 4-12 h.

[0047] In a preferred embodiment of the present invention, the calcination temperature of the low-temperature calcination is 200-550 °C. For example, 200 °C, 250 °C, 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, and any number between any two values, preferably 400-500 °C.

[0048] Among them, in the present invention, compared with high-temperature calcination, low-temperature calcination can, on the one hand, reduce the damage to the crystal structure of the catalyst and help improve the stability of the catalyst; on the other hand, the metal particle size on the catalyst prepared by low-temperature calcination is smaller and it is not easy to agglomerate, so the reaction performance of the catalyst is better.

[0049] In a preferred embodiment of the present invention, the heating rate of the low-temperature calcination is 1-15 °C / min, preferably 5-10 °C / min.

[0050] In a preferred embodiment of the present invention, the calcination time of the low-temperature calcination is 1-7 h, preferably 3-5 h.

[0051] In a preferred embodiment of the present invention, the calcination is carried out under the protection of an inert gas. Among them, the inert gas is preferably nitrogen.

[0052] In a preferred embodiment of the present invention, the furfural hydrogenation catalyst includes a carrier and an active component; among them, the carrier is a carbon carrier, and the active component is selected from one or more of Pd, Pt, and Ru; based on the total mass of the furfural hydrogenation catalyst, the content of the carrier is 75-99.7 wt%, preferably 90-97 wt%; the content of the active component is 0.3-25 wt%, preferably 4-10 wt%. Among them, in the present invention, the content of the active component is calculated based on the content of the metal element.

[0053] The second aspect of the present invention provides an application of a catalyst prepared by the method described in the first aspect of the present invention in the preparation of cyclopentanone by furfural hydrogenation.

[0054] In a preferred embodiment of the present invention, the application includes reducing the catalyst described in the first aspect of the present invention, and then contacting it with furfural, water and hydrogen to carry out a hydrogenation reaction to obtain cyclopentanone.

[0055] In a preferred embodiment of the present invention, the operating conditions for reduction include: the reducing gas includes a reducing gas and an inert gas. The reducing gas is selected from hydrogen and / or carbon monoxide, and the inert gas is selected from one or more of nitrogen, helium, and argon. In the mixed gas, the content of the reducing gas is 5-10 v%. The reduction temperature is 200-600 °C, preferably 300-400 °C, and the heating rate of the reduction temperature is 1-15 °C / min, preferably 5-10 °C / min. The reduction time is 1-12 h, preferably 2-8 h.

[0056] In a preferred embodiment of the present invention, the operating conditions for the hydrogenation reaction include: the mass ratio of furfural, water, and the catalyst described in the first aspect of the present invention is 10-25:75-750:1, the reaction temperature is 140-160 °C, and the reaction pressure is 2-4 MPa.

[0057] Among them, the catalyst prepared in the present invention can efficiently convert furfural into cyclopentanone under the above operating conditions. The conversion rate of furfural can be above 95%, and the yield of cyclopentanone is above 70%.

[0058] The third aspect of the present invention provides a method for preparing valerolactam, wherein the method includes the following steps:

[0059] (A) Contacting furfural, hydrogen, and the reduced catalyst in water to carry out a hydrogenation reaction to obtain cyclopentanone; wherein, the catalyst is the catalyst described in the first aspect of the present invention;

[0060] (B) Contacting the cyclopentanone, ammonia, hydrogen peroxide, and titanium silicalite in tert-butanol to carry out an oximation reaction to obtain cyclopentanone oxime;

[0061] (C) Contacting the cyclopentanone oxime with fuming sulfuric acid to carry out a Beckmann rearrangement reaction to obtain a rearrangement liquid;

[0062] (D) Contacting the rearrangement liquid with ammonia and demineralized water to carry out a neutralization reaction to obtain valerolactam.

[0063] Among them, in the present invention, step (A) is the same as the second aspect of the present invention, and steps (B)-(D) can be carried out according to the methods well known in the art, and the present invention will not elaborate one by one.

[0064] The present invention will be described in detail below through examples. Among them, in the present invention, the mass content of the active component in the catalyst is tested by inductively coupled plasma-optical emission spectrometry.

[0065] Catalyst Preparation Example 1

[0066] (1) At room temperature, mix the mixture of ethanol and water evenly with ammonia water (mass concentration of 28%) to obtain an alkaline solution with a pH value of 8.5; among them, in the mixture of ethanol and water, the volume ratio of ethanol to water is 1:2.5;

[0067] Disperse platinum nitrate in deionized water and stir to form a uniform solution to obtain a platinum nitrate solution with a concentration of 0.05 mol / L; add the platinum nitrate solution to the above-mentioned alkaline solution to obtain a mixed solution; among them, based on 1 mmol of platinum nitrate, the dosage of the alkaline solution is 1.6 L;

[0068] (2) Mix dopamine with deionized water and stir to form a uniform solution to obtain a dopamine solution with a concentration of 0.35 mol / L; add the dopamine solution to the above-mentioned mixed solution, stir at room temperature for 40 h, and then filter to obtain a solid material; among them, based on 1 g of dopamine, the dosage of the mixed solution is 260 mL;

[0069] (3) Wash the solid material with deionized water, dry it in an oven at 70 °C for 12 h, then place it in a tube furnace, heat it to 450 °C at a heating rate of 5 °C / min, calcine it at 450 °C under a nitrogen atmosphere for 3 h, take it out and cool it to room temperature to obtain a catalyst with a Pt loading of 4.0 wt%.

[0070] Catalyst preparation example 2

[0071] (1) At room temperature, mix ethanol and ammonia water (mass concentration of 28%) evenly to obtain an alkaline solution with a pH value of 8.7;

[0072] Disperse ammonium hexachloropalladate in water and stir to form a uniformly mixed solution to obtain an ammonium hexachloropalladate solution with a concentration of 0.02 mol / L; add the ammonium hexachloropalladate solution to the above-mentioned alkaline solution to obtain a mixed solution; among them, based on 1 mmol of ammonium hexachloropalladate, the dosage of the alkaline solution is 0.8 L;

[0073] (2) Mix dopamine with deionized water and stir to form a uniform solution to obtain a dopamine solution with a concentration of 0.5 mol / L; add the dopamine solution to the above-mentioned mixed solution, stir at room temperature for 30 h, and then filter to obtain a solid material; among them, based on 1 g of dopamine, the dosage of the mixed solution is 280 mL;

[0074] (3) Wash the solid material with deionized water, dry it in an oven at 70 °C for 8 h, then place it in a tube furnace, heat it to 500 °C at a heating rate of 10 °C / min, calcine it at 500 °C under a nitrogen atmosphere for 5 h, take it out and cool it to room temperature to obtain a catalyst with a Pd loading of 6.4 wt%.

[0075] Catalyst Preparation Example 3

[0076] (1) At room temperature, mix the mixed solution of ethanol and water with ammonia water (mass concentration of 28%) evenly to obtain an alkaline solution with a pH value of 9; among them, in the mixed solution of ethanol and water, the volume ratio of ethanol to water is 1:2.25;

[0077] Disperse platinum acetylacetonate in water and stir to form a uniform solution to obtain a platinum acetylacetonate solution with a concentration of 0.1 mol / L; add the platinum acetylacetonate solution to the above alkaline solution to obtain a mixed solution; among them, based on 1 mmol of platinum acetylacetonate, the dosage of the alkaline solution is 1.2 L;

[0078] (2) Mix dopamine with deionized water and stir to form a uniform solution to obtain a dopamine solution with a concentration of 0.8 mol / L; add the dopamine solution to the above mixed solution, stir at room temperature for 50 h, and then filter to obtain a solid material; among them, based on 1 g of dopamine, the dosage of the mixed solution is 300 mL;

[0079] (3) Wash the solid material with deionized water, dry it in an oven at 70 °C for 8 h, then place it in a tubular furnace, heat it to 400 °C at a heating rate of 8 °C / min, calcine it at 400 °C under a nitrogen atmosphere for 5 h, take it out and cool it to room temperature to obtain a catalyst with a Pt loading of 5.1 wt%.

[0080] Example 4

[0081] (1) At room temperature, mix triethylamine and water evenly to obtain an alkaline solution with a pH value of 8;

[0082] Add bis(ethylenediamine)platinum(II) acetate and ruthenium(III) chloride to the alkaline solution according to the molar ratio of platinum element to ruthenium element of 1.5:1, stir to form a uniform solution to obtain a mixed solution; among them, based on 1 mmol of metal ions (calculated as the total amount of platinum element and ruthenium element), the dosage of the alkaline solution is 1 L;

[0083] (2) Add dopamine to the above mixed solution, stir at room temperature for 60 h, and then filter to obtain a solid material; among them, based on 1 g of dopamine, the dosage of the mixed solution is 200 mL;

[0084] (3) Wash the solid material with deionized water, dry it in an oven at 70 °C for 8 h, then place it in a tubular furnace, heat it to 550 °C at a heating rate of 12 °C / min, calcine it at 550 °C under a nitrogen atmosphere for 1 h, take it out and cool it to room temperature to obtain a catalyst with a Pt loading of 2.3 wt% and a Ru loading of 0.8 wt%.

[0085] Example 5

[0086] Compared with Example 1, the difference lies in that: in step (1), ethanol is omitted, and water and ammonia water are mixed evenly at room temperature to obtain an alkaline solution with a pH value of 8.5.

[0087] A catalyst Pt / CN with a Pt loading of 4.2 wt% is obtained.

[0088] Comparative Example 1

[0089] Compared with Example 1, the difference lies in that: ammonia water is replaced with a carbonate buffer solution, that is, at room temperature, a mixed solution of ethanol and water is mixed evenly with the carbonate buffer solution to obtain an alkaline solution with a pH value of 8.5; among them, in the mixed solution of ethanol and water, the volume ratio of ethanol to water is 1:2.5.

[0090] A catalyst Pt / CN with a Pt loading of 3.8 wt% is obtained.

[0091] Comparative Example 2

[0092] Compared with Example 1, the difference lies in that: the calcination temperature is 700 °C.

[0093] A catalyst Pt / CN with a Pt loading of 6.9 wt% is obtained.

[0094] Preparation of cyclopentanone by hydrogenation of furfural, Examples 1-6 and Comparative Examples 1-2

[0095] 1 g of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2 are respectively reduced. Among them, the reducing gas is 8 v% H2 and 92 v% N2, the heating rate of the reduction temperature is 5 °C / min, the reduction temperature is 300 °C, and the reduction time is 6 h.

[0096] Then, it is transferred to a reaction kettle under nitrogen protection, and then 10 g of furfural and 100 g of water are added. After sealing, the gas in the kettle is replaced with N2 and H2 three times respectively to ensure good sealing of the reaction kettle; the temperature is raised to 150 °C using an automatic temperature controller, and then H2 is introduced until the reaction pressure reaches 3 MPa, and stirring is started to keep the pressure constant during the reaction.

[0097] After reacting for 4 h, the reaction is stopped, the kettle is opened for sampling and analysis, and the reaction product is analyzed using an Agilent 7890A gas chromatograph. The results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] By comparing Example 1 and Example 5, it can be seen that in the preparation method of the catalyst provided by the present invention, by adding an alcohol solvent to a weak base solution, the selectivity of the catalyst can be further improved, and the yield of cyclopentanone can be increased from 72.4% to 79.8%.

[0102] By comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be seen that in the preparation method of the catalyst provided by the present invention, the interaction between a specific alkaline solution and low-temperature calcination can significantly improve the furfural conversion rate and the cyclopentanone yield of the catalyst in the furfural hydrogenation reaction.

[0103] Cyclic performance test

[0104] The cyclic performance test was carried out using Example 1 and Comparative Example 2. It was the same as the above-mentioned reaction for preparing cyclopentanone by furfural hydrogenation, except that after reacting continuously for 4 h, the reaction was stopped, the catalyst was separated, washed three to four times with deionized water and ethanol, and after drying, the furfural hydrogenation reaction was repeated again, and the reaction was carried out 5 times in total.

[0105] At the end of each reaction, a sample was taken for analysis, and the reaction product was analyzed by Agilent 7890A gas chromatography. The analysis results are shown in Table 2.

[0106] Table 2

[0107]

[0108]

[0109] As can be seen from Table 2, after 5 cycles of the catalyst prepared in Example 1 of the present invention, the catalytic activity of the catalyst remained basically unchanged, indicating that the catalyst has good stability. After 5 cycles of the catalyst prepared in Comparative Example 1, the furfural conversion rate of the catalyst decreased from 99.0% to 85.5%, and the cyclopentanone yield decreased from 71.3% to 54.1%, indicating that the stability of the catalyst is poor.

[0110] According to the above cyclic performance test method, the catalysts prepared in Examples 2-6 were subjected to cyclic performance test under the same conditions, and the results were basically the same as those of Example 1. After 5 cycles, the decrease ranges of the furfural conversion rate and the cyclopentanone yield of the catalyst were both within 3%.

[0111] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that, The method includes the following steps: (1) Adding an active component precursor into an alkaline solution to obtain a mixed solution; wherein, the active component precursor is selected from one or more of Pd-containing compounds, Pt-containing compounds, and Ru-containing compounds; the alkaline solution is selected from one or more of ammonia water, AMP buffer solution, and triethylamine aqueous solution; (2) Adding dopamine into the mixed solution for redox reaction to obtain a solid material; (3) Calcining the solid material at a low temperature to obtain a catalyst; wherein, the calcination temperature of the low-temperature calcination is 200 - 550 °C.

2. The preparation method according to claim 1, characterized in that, The Pt-containing compound is selected from one or more of chloroplatinic acid, chloroplatinous acid, platinum nitrate, bis(ethylenediamine)platinum(II) acetate, and platinum(II) acetylacetonate; Preferably, the Pd-containing compound is selected from one or more of ammonium hexachloropalladate, palladium nitrate, palladium acetate, palladium acetylacetonate, and dinitrodiamminepalladium(II); Preferably, the Ru-containing compound is selected from one or more of ruthenium(III) chloride, nitrosyl ruthenium nitrate, ruthenium acetate, ruthenium(II) acetate, and ruthenium(III) acetylacetonate; 3. The preparation method according to claim 1 or 2, characterized in that, The pH value of the alkaline solution is 8 - 10, preferably 8.5 - 9.

4. The preparation method according to claim 3, wherein, Adjust the pH of the alkaline solution by adding water and / or an alcohol solvent; Preferably, the alcohol solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol.

5. The preparation method according to any one of claims 1-4, characterized in that, Based on 1 mmol of the active component precursor, the dosage of the alkaline solution is 0.2 - 4 L, preferably 0.5 - 2 L.

6. The preparation method according to any one of claims 1-5, characterized in that, Based on 1 g of the dopamine, the dosage of the mixed solution is 160 - 480 mL, preferably 240 - 320 mL; Preferably, the operating conditions of the redox reaction include: the reaction temperature of the redox reaction is room temperature, and the reaction time is 10 - 70 h, preferably 30 - 50 h.

7. The preparation method according to any one of claims 1-6, characterized in that, The calcination temperature of the low-temperature calcination is 400 - 500 °C.

8. The preparation method according to any one of claims 1-7, characterized in that, The heating rate of the low-temperature calcination is 1 - 15 °C / min, preferably 5 - 10 °C / min; Preferably, the calcination time of the low-temperature calcination is 1 - 7 h, preferably 3 - 5 h.

9. Application of the catalyst prepared by the method according to any one of claims 1 - 8 in the hydrogenation of furfural to prepare cyclopentanone.

10. A method for preparing valerolactam, characterized in that, The method includes the following steps: (A) Contacting furfural, hydrogen, and the reduced catalyst in water for hydrogenation reaction to obtain cyclopentanone; wherein, the catalyst is the catalyst according to any one of claims 1 - 8; (B) Contacting the cyclopentanone, ammonia, hydrogen peroxide, and titanium silicalite in tert-butanol for oximation reaction to obtain cyclopentanone oxime; (C) Contacting the cyclopentanone oxime with fuming sulfuric acid for Beckmann rearrangement reaction to obtain a rearrangement solution; (D) Contacting the rearrangement solution with ammonia and demineralized water for neutralization reaction to obtain valerolactam.

Images