Metal catalyst and its preparation method and application

Abstract

The invention discloses a metal catalyst and a preparation method and application thereof. The carrier of the metal catalyst is Al2O3, and the active component is Co and / or Ni; wherein the molar ratio of metal atoms to Al atoms in the metal catalyst is 1:5-40; and / or the Al2O3 is modified by acidification treatment. The metal catalyst has excellent furfural liquid phase hydrogenation performance. In the reaction of furfural liquid phase hydrogenation to prepare 2-methylfuran, the furfural conversion rate is as high as 100%, and the 2-methylfuran yield is as high as 99%. The preparation method of the catalyst only requires low-temperature reduction under a hydrogenation agent, and the preparation process is simple and green.

Description

Technical Field

[0001] The present invention relates to the field of nano catalysts, and in particular to a metal catalyst and a preparation method and application thereof. Background Art

[0002] 2-Methylfuran is an important chemical raw material with broad application prospects. It can be used as an organic solvent and an organic synthesis intermediate. It has important applications in the fields of chemical industry, medicine, pesticides, and energy. In industry, chromium and copper catalysts are usually used to catalyze the conversion of furfural to produce 2-methylfuran. Since chromium causes serious environmental pollution during the reaction process, if it is discharged without treatment, it will cause excessive chromium in the soil and groundwater, and it will cause irreversible damage when absorbed by the human body. At the same time, copper-based catalysts also have many shortcomings in the catalytic reaction of furfural catalytic hydrogenation to produce 2-methylfuran, such as the low yield and selectivity of 2-methylfuran, and the Cu particles are easily lost during the reaction process, and can cause more side reactions to occur, and the repeated recycling effect of the catalyst is poor.

[0003] The literature (Applied Catalysis B: Environmental, 2021, 282, 119576) studied the influence of Cu species in the catalytic preparation of 2-methylfuran from furfural, and verified the effectiveness of Cu for the reaction. Cu / SiO2 catalysts are mostly used for furfural hydrogenation reactions, but because SiO2 is a neutral substance, the interaction with the active component is not close enough, so the catalytic performance of furfural still needs to be improved. In the literature (Catalysis Today, 2021, 365: 291-300), the precious metal Pd was added to the Cu-SiO2 catalyst system to increase the yield of 2-methylfuran. However, the catalyst will also experience instability of the active components during the reaction, resulting in a decrease in catalyst performance. This makes it crucial to study the preparation process of the catalyst and regulate the interaction between the active component and the carrier to improve the catalyst performance. Summary of the invention

[0004] The purpose of the present invention is to provide a metal catalyst and a preparation method and application thereof. The metal catalyst has excellent furfural liquid phase hydrogenation performance. In the reaction of furfural liquid phase hydrogenation to produce 2-methylfuran, the furfural conversion rate is as high as 100%, and the 2-methylfuran yield is as high as 99%. The preparation method of the catalyst only requires low-temperature reduction under a hydrogenation reagent, and the preparation process is simple, green and environmentally friendly.

[0005] In order to achieve the above object, the present invention provides a metal catalyst, the carrier of the metal catalyst is Al2O3, and the active component is Co and / or Ni;

[0006] Wherein, the Al2O3 is modified by being treated with organic acid.

[0007] The present invention also provides a method for preparing the metal catalyst, the preparation method comprising:

[0008] 1) Acidifying Al2O3, first filtering, first washing, and first drying to obtain carrier Al2O3;

[0009] 2) dissolving the metal salt in a solvent, adding a carrier Al2O3, and then adding a reducing agent to obtain a mixed solution for reaction, filtering, washing, and drying to obtain a metal catalyst;

[0010] Wherein, the metal salt is Co salt and / or Ni salt.

[0011] The present invention further provides an application of the metal catalyst in the reaction of preparing 2-methylfuran by liquid phase hydrogenation of furfural.

[0012] The present invention further provides a method for preparing 2-methylfuran by hydrogenating furfural, the method comprising: in a hydrogen environment, a metal catalyst catalyzes a liquid phase hydrogenation reaction of furfural in a micro slurry bed reaction device to convert it into 2-methylfuran;

[0013] Wherein, the metal catalyst is the metal catalyst according to claim 1 or 2; and / or,

[0014] The mass concentration of furfural is 0.01-0.05 g / mL; and / or,

[0015] The pressure of the hydrogen is 0.6-1 MPa; and / or,

[0016] The liquid phase hydrogenation reaction includes: a temperature of 180-260° C. and a time of 2-6 hours; preferably a temperature of 220-240° C. and a time of 4 hours.

[0017] In the above technical scheme, the present invention effectively improves the surface acidic group characteristics of the Al2O3 carrier by treating and modifying the Al2O3 carrier with an organic acid, which is beneficial to promoting the reaction between the Al2O3 carrier and Ni or Co; on the other hand, the liquid phase in-situ reduction method is used to prepare the catalyst, which can effectively avoid the thermal agglomeration of the active components of the catalyst and the reduction in the number of active centers. At the same time, since the method only needs to be carried out at low temperatures, the catalyst preparation cycle can be shortened and the energy consumption can be effectively reduced; and the prepared catalyst exhibits excellent furfural liquid phase hydrogenation performance.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 The product gas chromatogram of the liquid phase hydrogenation reaction of furfural using the Co / Al2O3-N (1:15) catalyst prepared in Example 1;

[0021] Figure 2 is a transmission electron microscopy (TEM) photograph of the Co / Al2O3-N (1:15) catalyst prepared in Example 1;

[0022] Figure 3 This is a transmission electron microscopy (TEM) photograph of the Ni / Al2O3-A (1:15) catalyst prepared in Example 6. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0025] The present invention provides a metal catalyst, the carrier of the metal catalyst is Al2O3, and the active component is Co and / or Ni;

[0026] Wherein, the Al2O3 is modified by being treated with organic acid.

[0027] The metal catalyst of the invention has excellent furfural liquid phase hydrogenation performance, and furfural can be completely converted.

[0028] According to a preferred embodiment of the present invention, the molar ratio of metal atoms to Al atoms can be selected within a wide range. However, in order to make the catalyst have better catalytic performance, the molar ratio of metal atoms to Al atoms in the metal catalyst is 1:5-40.

[0029] The present invention also provides a method for preparing the metal catalyst, the preparation method comprising:

[0030] 1) Acidifying Al2O3, first filtering, first washing, and first drying to obtain carrier Al2O3;

[0031] 2) dissolving the metal salt in a solvent, adding a carrier Al2O3, and then adding a reducing agent to obtain a mixed solution for reaction, filtering, washing, and drying to obtain a metal catalyst;

[0032] Wherein, the metal salt is Co salt and / or Ni salt.

[0033] In the catalyst preparation method of the present invention, the catalyst only needs to be reduced at low temperature in the presence of a hydrogenation reagent, and the preparation process is simple, green and environmentally friendly.

[0034] According to a preferred embodiment of the present invention, the conditions for the acidification treatment can be selected within a wide range, but in order to improve the properties of the surface acidic groups of the carrier Al2O3 and promote the reaction between the carrier and Ni or Co, in step 1), the acidification treatment includes: treating in an acidic reagent at a temperature of 80-150°C for 1-3h.

[0035] According to a preferred embodiment of the present invention, the type of the acidic agent can be selected within a wide range, but in order to effectively improve the surface acidic groups of the carrier Al2O3, the acidic agent is at least one of citric acid, formic acid and acetic acid.

[0036] According to a preferred embodiment of the present invention, the concentration of the acidic reagent can be selected within a wide range, but in order to completely modify the carrier Al2O3, the mass fraction of the acidic reagent is 10% to 30%.

[0037] According to a preferred embodiment of the present invention, the type of metal salt can be selected within a wide range, but in order to make the catalyst have better catalytic hydrogenation performance, in step 2), the metal salt is at least one of Co nitrate, Co halide, Co acetate, Ni nitrate, Ni halide and Ni acetate.

[0038] According to a preferred embodiment of the present invention, the type of reducing agent can be selected from a wide range, but in order to enable the catalyst to be rapidly reduced at low temperature, in step 2), the reducing agent is sodium borohydride and / or potassium borohydride.

[0039] According to a preferred embodiment of the present invention, in step 2), the type of solvent can be selected from a wide range, but in order to make the reduction reaction proceed quickly and completely, in step 2), the solvent is deionized water.

[0040] According to a preferred embodiment of the present invention, the reaction conditions in step 2) can be selected within a wide range, but in order to allow the carrier and the metal atoms to react and combine better, in step 2), the reaction conditions include: covering and sealing the mixed solution, and stirring at a temperature of 40-80°C for 3-24h.

[0041] According to a preferred embodiment of the present invention, in step 2), the conditions for the second washing can be selected within a wide range, but in order to make the catalyst have better catalytic hydrogenation performance, in step 2), the conditions for the second washing include: washing the filtered product with deionized water until it is neutral.

[0042] The present invention further provides an application of the metal catalyst in the reaction of preparing 2-methylfuran by liquid phase hydrogenation of furfural.

[0043] The present invention further provides a method for preparing 2-methylfuran by hydrogenating furfural, the method comprising: in a hydrogen environment, a metal catalyst catalyzes a liquid phase hydrogenation reaction of furfural in a micro slurry bed reaction device to convert it into 2-methylfuran;

[0044] Wherein, the metal catalyst is the metal catalyst described in the above preparation method;

[0045] According to a preferred embodiment of the present invention, the mass concentration of furfural can be selected within a wide range, but in order to make the conversion efficiency of the reaction higher, the mass concentration of furfural is 0.01-0.05 g / mL.

[0046] According to a preferred embodiment of the present invention, the pressure of the hydrogen can be selected within a wide range, but in order to completely convert furfural into 2-methylfuran, the pressure of the hydrogen is 0.6-1 MPa.

[0047] According to a preferred embodiment of the present invention, the conditions of the liquid phase hydrogenation reaction can be selected within a wide range, but in order to completely convert furfural into 2-methylfuran, the conditions of the liquid phase hydrogenation reaction include: temperature of 180-260°C and time of 2-6h.

[0048] According to a preferred embodiment of the present invention, the conditions of the liquid phase hydrogenation reaction can be selected within a wide range, but in order to completely convert furfural into 2-methylfuran, the conditions of the liquid phase hydrogenation reaction include: a temperature of 220-240° C. and a time of 4 hours.

[0049] The metal catalyst of the invention is used in the reaction of preparing 2-methylfuran by liquid phase hydrogenation of furfural, and the furfural conversion rate is as high as 100%, and the 2-methylfuran yield is as high as 99%.

[0050] The present invention will be described in detail below by way of examples. In the following examples, the drugs and medicaments are all conventional commercial products.

[0051] Example 1

[0052] (1) Weigh 10 g of Al2O3 powdery particles, place them in a 10% citric acid solution, and acidify them at 100°C for 3 h. Then, wash them with deionized water, dry them at 110°C, and set them aside.

[0053] (2) Weigh 2.31 g of cobalt nitrate hexahydrate, fully dissolve it in 15 mL of deionized water, and fully stir and mix it with the Al2O3 carrier treated in step (1) for 0.5 h, add sodium borohydride, cover and seal, stir at 40°C for 12 h, wash with deionized water until neutral, place in a vacuum desiccator at 40°C and dry for 10 h to obtain a Co / Al2O3-N (1:15) catalyst, recorded as Cat 1.

[0054] Its TEM image is as follows Figure 2 As shown, it can be seen that the particle size distribution is at most 3.5-4.0 nm, and the average particle size is 3.98 nm.

[0055] Example 2

[0056] The implementation steps and conditions were the same as those in Example 1, except that the 10% citric acid solution was replaced with a 10% acetic acid solution to obtain a Co / Al2O3-A (1:15) catalyst, denoted as Cat 2.

[0057] Its TEM image is basically consistent with that of Example 1.

[0058] Example 3

[0059] The implementation steps and conditions were the same as those of Example 1, except that the mass of cobalt nitrate hexahydrate was changed from 2.31 g to 3.46 g, to obtain a Co / Al2O3-A (1:10) catalyst, recorded as Cat 3.

[0060] Its TEM image is basically consistent with that of Example 1.

[0061] Example 4

[0062] The implementation steps and conditions were the same as those in Example 1, except that the mass of cobalt nitrate hexahydrate was changed from 2.31 g to 6.92 g, to obtain a Co / Al2O3-A (1:5) catalyst, recorded as Cat 4.

[0063] Its TEM image is basically consistent with that of Example 1.

[0064] Example 5

[0065] The implementation steps and conditions are the same as those of Example 1, except that the mass of cobalt nitrate hexahydrate is changed from 2.31 g to 0.87 g, to obtain a Co / Al2O3-A (1:40) catalyst, recorded as Cat 5.

[0066] Its TEM image is basically consistent with that of Example 1.

[0067] Example 6

[0068] The implementation steps and conditions are the same as those of Example 1, except that the cobalt nitrate hexahydrate is replaced by nickel nitrate with a mass of 1.91 g to obtain a Ni / Al2O3-A (1:15) catalyst, recorded as Cat 6.

[0069] Its TEM image is as follows Figure 3 As shown, it can be seen that the particle size distribution is mainly between 2.0-3.5 nm, and the average particle size is 2.97 nm.

[0070] Example 7

[0071] The implementation steps and conditions are the same as those of Example 6, except that the mass of nickel nitrate is changed from 1.91 g to 2.85 g, to obtain a Ni / Al2O3-A (1:10) catalyst, recorded as Cat 7.

[0072] Its TEM image is basically consistent with that of Example 6.

[0073] Example 8

[0074] The implementation steps and conditions are the same as those of Example 6, except that nickel nitrate is replaced by nickel chloride with a mass of 1.56 g to obtain a Ni / Al2O3-A (1:15) catalyst, recorded as Cat 8.

[0075] Its TEM image is basically consistent with that of Example 6.

[0076] Example 9

[0077] The implementation steps and conditions were the same as those in Example 7, except that the mass of furfural was changed from 0.5 g to 0.25 g, to obtain a Ni / Al2O3-A (1:15) catalyst, recorded as Cat 9.

[0078] Its TEM image is basically consistent with that of Example 6.

[0079] Example 10

[0080] The implementation steps and conditions were the same as those in Example 1, except that the mass of furfural was changed from 0.5 g to 0.1 g, to obtain a Ni / Al2O3-N (1:15) catalyst, denoted as Cat 10.

[0081] Its TEM image is basically consistent with that of Example 6.

[0082] Embodiment 11

[0083] (1) Weigh 10 g of Al2O3 powdery particles, place them in a 30% citric acid solution, and acidify them at 80°C for 1 h. Then, wash them with deionized water, dry them at 100°C, and set them aside.

[0084] (2) Weigh 2.31 g of cobalt nitrate hexahydrate, fully dissolve it in 15 mL of deionized water, and fully stir and mix it with the Al2O3 carrier treated in step (1) for 0.5 h, add potassium borohydride, cover and seal, stir at 80°C for 3 h, wash with deionized water until neutral, place in a vacuum desiccator at 40°C and dry for 10 h to obtain a Co / Al2O3-N (1:15) catalyst, recorded as Cat 11.

[0085] Its TEM image is basically consistent with that of Example 1.

[0086] Example 12

[0087] (1) Weigh 10 g of Al2O3 powdery particles, place them in a 10% citric acid solution, and perform acidification treatment at 150°C for 3 h. Then, wash them with deionized water, dry them at 120°C, and set them aside.

[0088] (2) Weigh 2.31 g of cobalt nitrate hexahydrate, fully dissolve it in 15 mL of deionized water, and fully stir and mix it with the Al2O3 carrier treated in step (1) for 0.5 h, add sodium borohydride, cover and seal, stir at 40°C for 24 h, wash with deionized water until neutral, place in a vacuum desiccator at 40°C and dry for 10 h to obtain a Co / Al2O3-N (1:15) catalyst, recorded as Cat 12.

[0089] Its TEM image is basically consistent with that of Example 1.

[0090] Comparative Example 1

[0091] The implementation steps and conditions were the same as those in Example 1, except that the 10% citric acid solution was replaced with a 10% sodium hydroxide solution to obtain a Co / Al2O3-S (1:15) catalyst, denoted as Cat A.

[0092] Comparative Example 2

[0093] The implementation steps and conditions were the same as those in Example 1, except that Al2O3 was not pre-treated with 10% citric acid solution, and a Co / Al2O3-NE (1:15) catalyst was obtained, which was designated as Cat B.

[0094] Application Example 1

[0095] 0.2 g of catalysts Cat1-Cat5, Cat 10-12, Cat A and Cat B, 0.5 g of furfural and 10 mL of isopropanol were weighed respectively and put into a slurry bed reactor. The air in the reactor was replaced by hydrogen and the pressure was maintained at 1.0 MPa. The reaction temperature was controlled at 220 ° C. The reaction was heated and stirred for 4 h. The filtrate was collected after cooling to room temperature. The product was analyzed by gas chromatography. The performance of the furfural liquid phase hydrogenation reaction is shown in Table 1.

[0096] The product gas chromatogram of the furfural reaction of the catalyst Cat1 prepared in Example 1 is as follows: Figure 1 shown.

[0097] Application Example 2

[0098] 0.2 g of catalyst Cat 6-9, 0.5 g of furfural and 10 ml of isopropanol were weighed and put into a slurry bed reactor. The air in the reactor was replaced by hydrogen and the pressure was maintained at 0.6 MPa. The reaction temperature was controlled at 240 ° C. The reaction was heated and stirred for 4 h. The filtrate was collected after cooling to room temperature. The product was analyzed by gas chromatography. The performance of the furfural liquid phase hydrogenation reaction is shown in Table 1.

[0099] Table 1 Furfural liquid phase hydrogenation performance over different catalysts

[0100]

[0101]

[0102] It can be seen from Table 1 that when the ratio of Co atoms or Ni atoms to Al atoms in the catalyst is between 1:5-40, the conversion rate of furfural is as high as 100%, and when the molar ratio of Co atoms or Ni atoms to Al atoms is between 1:15-40, not only the conversion rate of furfural is as high as 100%, but also the yield of 2-methylfuran is more than 80%.

[0103] Further, through Figure 1 As shown in the product gas chromatogram of the furfural liquid-phase hydrogenation reaction using the catalyst Cat1 prepared in Example 1, there is no furfural peak, indicating that the furfural is completely converted. The product gas chromatograms of the furfural liquid-phase hydrogenation reaction using the catalysts Cat1-Cat12 are basically the same and will not be described in detail here.

[0104] At the same time, in the furfural liquid-phase hydrogenation reaction, the furfural conversion rates of the catalyst Cat A obtained by alkaline treatment of the carrier Al2O3 in Comparative Example 1 and the catalyst Cat B obtained by untreated carrier Al2O3 in Comparative Example 2 were 97% and 88%, and the 2-methylfuran yields were 53% and 27%, respectively, which were both lower than the furfural conversion rate and 2-methylfuran yield of the catalyst obtained by acidic treatment of the carrier Al2O3 in the present invention. It can be seen that the acidic treatment of the carrier Al2O3 in the present invention effectively improves the surface acidic group characteristics of the Al2O3 carrier, which is beneficial to promote the reaction between the carrier and Ni or Co, so that the prepared catalyst exhibits excellent furfural liquid-phase hydrogenation performance.

[0105] Moreover, Figure 2-3 From the TEM images of the Co catalyst and the Ni catalyst, it can be seen that the particle size of the catalyst prepared by the present invention is small, the average particle size of the Co catalyst is 3.98 nm, and the average particle size of the Ni catalyst is 2.97 nm, indicating that the catalyst of the present invention has good dispersibility.

[0106] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0107] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0108] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A metal catalyst, characterized in that The carrier of the metal catalyst is Al2O3, and the active component is Co and / or Ni; Wherein, the Al2O3 is modified by being treated with organic acid; The organic acid is at least one of citric acid, formic acid and acetic acid; The molar ratio of Co and / or Ni to Al in the metal catalyst is 1:5-40; The mass fraction of the organic acid is 10%-30%.

2. A method for preparing the metal catalyst according to claim 1, characterized in that: The preparation method comprises: 1) Acidifying Al2O3, first filtering, first washing, and first drying to obtain carrier Al2O3; 2) dissolving the metal salt in a solvent, adding a carrier Al2O3, and then adding a reducing agent to obtain a mixed solution for reaction, filtering, washing, and drying to obtain a metal catalyst; Wherein, the metal salt is Co salt and / or Ni salt.

3. The preparation method according to claim 2, wherein In step 1), the acidification treatment comprises: treating in an organic acid at a temperature of 80-150° C. for 1-3 hours.

4. The preparation method according to claim 3, wherein The organic acid is at least one of citric acid, formic acid and acetic acid; and / or, The mass fraction of the organic acid is 10%-30%.

5. The preparation method according to claim 2, wherein: In step 2), the metal salt is at least one of Co nitrate, Co halide, Co acetate, Ni nitrate, Ni halide and Ni acetate.

6. The preparation method according to claim 2, wherein: In step 2), the reducing agent is sodium borohydride and / or potassium borohydride; and / or, The solvent is deionized water.

7. The preparation method according to claim 2, wherein: In step 2), the reaction conditions include: sealing the mixed solution with a lid, and stirring at a temperature of 40-80° C. for 3-24 h; and / or, The second washing conditions include: washing the filtered product with deionized water until it becomes neutral.

8. Use of the metal catalyst according to claim 1 in the reaction of preparing 2-methylfuran by liquid phase hydrogenation of furfural.

9. A method for preparing 2-methylfuran by hydrogenating furfural, characterized in that: The method comprises: in a hydrogen environment, a metal catalyst catalyzes furfural to carry out a liquid phase hydrogenation reaction in a micro slurry bed reaction device to convert it into 2-methylfuran; Wherein, the metal catalyst is the metal catalyst according to claim 1; and / or, The mass concentration of furfural is 0.01-0.05 g / mL; and / or, The pressure of the hydrogen is 0.6-1 MPa; and / or, The conditions of the liquid phase hydrogenation reaction include: temperature of 180-260° C. and time of 2-6 hours.

10. The method according to claim 9, wherein: The conditions of the liquid phase hydrogenation reaction include: temperature of 220-240° C. and time of 4 hours.

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