A supported bimetallic catalyst, its preparation method and use

Abstract

The application discloses a supported bimetallic catalyst and a preparation method and application thereof. The catalyst comprises nitrogen-doped graphene oxide / porous carbon and rhodium and cobalt supported thereon; the molar ratio of cobalt to rhodium is 1:10-1:150 in terms of elements. The catalyst can significantly improve the reaction activity of hydroformylation and the aldehyde selectivity by nitrogen-doping graphene oxide / porous carbon and supporting rhodium and cobalt bimetallic active centers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydroformylation, and particularly relates to a supported bimetallic catalyst, a preparation method and application thereof. BACKGROUND

[0002] Currently, the industrial hydroformylation production process is mainly divided into homogeneous catalysis and two-phase catalysis. Homogeneous catalysis has the advantages of fast reaction rate and high activity, but the product and the catalyst need to be separated by distillation. With the increase of carbon chain, the boiling point of the hydroformylation reaction product, high carbon aldehyde, increases, and a higher temperature is needed to separate the product. However, the rhodium-based catalyst with high activity is easy to be deactivated at high temperature, so the high-temperature distillation used in the homogeneous catalysis process will cause the loss of the noble metal catalyst, increasing the production cost.

[0003] CN106362766A discloses a Rh / CoO nano catalyst, a preparation method and application thereof. Rh atoms are independently and uniformly loaded on the surface of CoO flake with two-dimensional crystal structure. The preparation method comprises the following steps: mixing CoO flake with two-dimensional crystal structure and deionized water to obtain a mixed solution A; adding sodium hexachlororhodate solution into the mixed solution A to obtain a mixed solution B; stirring the mixed solution B at room temperature, washing and vacuum drying to obtain the Rh / CoO nano catalyst.

[0004] However, the above catalyst cannot balance the catalyst activity and product selectivity. SUMMARY

[0005] In view of the above problems existing in the prior art, the present application provides a new supported bimetallic catalyst and a preparation method thereof. The catalyst is prepared by nitrogen-doping graphene oxide / porous carbon and loading rhodium and cobalt bimetallic active centers, which can significantly improve the reaction activity and aldehyde selectivity of the hydroformylation reaction. Moreover, the catalyst as a heterogeneous catalyst has good recovery effect after the hydroformylation reaction, and the separated and recovered catalyst composition can be recycled.

[0006] The first aspect of the present application provides a supported bimetallic catalyst, which comprises nitrogen-doped graphene oxide / porous carbon and rhodium and cobalt supported thereon; the molar ratio of cobalt to rhodium is 1:10-1:150, preferably 1:25-1:150, in terms of elements.

[0007] In the present application, "graphene oxide / porous carbon" refers to graphene oxide or porous carbon.

[0008] According to some embodiments of the catalyst of the present application, the preparation method of the nitrogen-doped graphene oxide / porous carbon comprises: mixing a dispersion liquid containing graphene oxide / porous carbon with a nitrogen-containing compound, hydrothermal reaction, and then cooling, washing, filtering and vacuum drying.

[0009] According to some embodiments of the catalyst of the present application, the content of graphene oxide / porous carbon is 1.0-6.0 mg per mL of the dispersion containing graphene oxide / porous carbon.

[0010] According to some embodiments of the catalyst of the present application, the nitrogen-containing compound is urea.

[0011] According to some embodiments of the catalyst of the present application, the weight ratio of graphene oxide / porous carbon to urea is 1:10-1:300.

[0012] According to some embodiments of the catalyst of the present application, the temperature of the hydrothermal reaction is 100-200℃, and the time of the hydrothermal reaction is 6-36 h.

[0013] According to some embodiments of the catalyst of the present application, the content of rhodium is 0.1-10 wt% on an elemental basis based on the weight of the catalyst. In the present application, the loading content of rhodium in the catalyst can be changed by adjusting the concentration of rhodium impregnation solution, but it is found through measurement that the supported bimetallic catalyst of the present application has a better effect when the content of rhodium is in the range of 0.1-10 wt% on an elemental basis.

[0014] According to some embodiments of the catalyst of the present application, the supported bimetallic catalyst is used for olefin hydroformylation reaction.

[0015] The second aspect of the present application provides a preparation method of a supported bimetallic catalyst, comprising:

[0016] (1) mixing nitrogen-doped graphene oxide / porous carbon and a solvent to obtain a mixed solution A;

[0017] (2) mixing the mixed solution A with a rhodium-containing compound to obtain a mixed solution B;

[0018] (3) heating the mixed solution B under reflux in nitrogen protection, and after cooling, washing, filtering, and vacuum drying, obtaining a rhodium-loaded intermediate;

[0019] (4) impregnating the rhodium-loaded intermediate with a cobalt acetate solution, and filtering, washing, and vacuum drying to obtain a solid;

[0020] (5) heating the solid in a mixed gas atmosphere of H2 / He, and cooling.

[0021] According to some embodiments of the method of the present application, the amount of solvent is 400-600 mL per g of nitrogen-doped graphene oxide / porous carbon.

[0022] According to some embodiments of the method of the present application, the content of the rhodium compound in the solution B is 0.01-0.5 mg in terms of rhodium element.

[0023] According to some embodiments of the method of the present application, the weight of the rhodium-loaded intermediate is 0.001-0.003 g per mL of the cobalt acetate solution.

[0024] According to some embodiments of the method of the present application, the concentration of the cobalt acetate in terms of cobalt element is 0.0005-0.03 mg per mL of the cobalt acetate solution.

[0025] According to some embodiments of the method of the present application, the content of H2 in the mixed H2 / He atmosphere is 10-30 vol%.

[0026] According to some embodiments of the method of the present application, the heating condition includes a temperature of 100-200 °C and a time of 10-60 min.

[0027] According to some embodiments of the method of the present application, the preparation method of the nitrogen-doped graphene oxide / porous carbon includes mixing a dispersion liquid containing graphene oxide / porous carbon with a nitrogen-containing compound, hydrothermal reaction, and then cooling, washing, filtering, and vacuum drying.

[0028] According to some embodiments of the method of the present application, the content of the graphene oxide / porous carbon is 1.0-6.0 mg per mL of the dispersion liquid containing graphene oxide / porous carbon.

[0029] According to some embodiments of the method of the present application, the nitrogen-containing compound is urea.

[0030] According to some embodiments of the catalyst of the present application, the weight ratio of the dispersion liquid of graphene oxide / porous carbon to urea is 1:10-1:300.

[0031] According to some embodiments of the method of the present application, the temperature of the hydrothermal reaction is 100-200 °C, and the time of the hydrothermal reaction is 6-36 h.

[0032] According to some embodiments of the preparation method of the present application, the rhodium-containing compound is shown in formula (I):

[0033] Rh(L 1 ) x (L 2 ) y (L 3 ) z Formula (I)

[0034] wherein, L1 selected from the group consisting of carbonyl, halogen, acetylacetone, diphenylphosphine, cyclooctadiene, norbornene and triphenylphosphine; L 2 and L 3 are the same or different, each independently selected from the group consisting of hydrogen, carbonyl, halogen, acetylacetone, diphenylphosphine, cyclooctadiene, norbornene and triphenylphosphine, x is an integer from 1 to 3, y and z are each independently an integer from 0 to 4, and x+y+z≤5.

[0035] According to some embodiments of the preparation method of the present application, the rhodium-containing compound is at least one selected from the group consisting of rhodium trichloride, acetylacetone dicarbonyl rhodium, monochloromonocarbonyl bis(trisulfonated triphenylphosphine trisodium salt) rhodium, monochloromonocarbonyl bis(disulfonated triphenylphosphine disodium salt) rhodium, monochloromonocarbonyl bis(monosulfonated triphenylphosphine monosodium salt) rhodium and monohydrogen monocarbonyl tris(trisulfonated triphenylphosphine trisodium salt) rhodium.

[0036] According to some embodiments of the method of the present application, a preparation method of a nitrogen-doped graphene oxide / porous carbon supported bimetallic catalyst comprises, but is not limited to: mixing nitrogen-doped graphene oxide / porous carbon and a solvent to obtain a mixed solution A; adding a rhodium-containing compound to the mixed solution A, and stirring uniformly to obtain a mixed solution B; heating, stirring and refluxing the mixed solution B under nitrogen protection, and then washing, filtering and vacuum drying overnight to obtain rhodium-supported nitrogen-doped graphene oxide / porous carbon; immersing the obtained rhodium-supported nitrogen-doped graphene oxide / porous carbon in a cobalt acetate solution, stirring under inert gas protection, and then filtering, washing and vacuum drying to obtain a black solid; heating the obtained black solid in a mixed gas atmosphere of H2 / He, and then cooling to obtain a nitrogen-doped graphene oxide / porous carbon supported bimetallic catalyst.

[0037] The third aspect of the present application provides a supported bimetallic catalyst prepared according to the above preparation method. The catalyst comprises nitrogen-doped graphene oxide / porous carbon and rhodium and cobalt supported thereon; the molar ratio of cobalt to rhodium is 1:10-1:150, preferably 1:25-1:150, in terms of elements.

[0038] According to the supported bimetallic catalyst of the present application, the content of rhodium is 0.1-10% by weight, in terms of elements, based on the weight of the catalyst.

[0039] The fourth aspect of the present application provides the use of the above supported bimetallic catalyst or the above preparation method in olefin hydroformylation.

[0040] The present application has the following beneficial effects:

[0041] (1) The use of the supported bimetallic catalyst of the present application can significantly improve the reaction activity and aldehyde selectivity of the hydroformylation reaction, and the effect is remarkable.

[0042] (2) After the reaction is completed, there is a good recovery effect, the separated catalyst composition can be recycled, the production cost is reduced, and the industrialized production application is beneficial. DETAILED DESCRIPTION

[0043] In order to make the present application easier to understand, the present application will be described in detail below in conjunction with examples, which only serve to illustrate the present application and are not limited to the scope of application of the present application.

[0044] Example 1

[0045] A graphene oxide dispersion solution with a concentration of 4 mg / mL (the content of graphene oxide is 4 mg per mL of graphene oxide dispersion solution) was prepared, and urea was added under vigorous stirring, the weight ratio of graphene oxide dispersion solution to urea was 1:200, after vigorous stirring at room temperature for 2 h, the mixture was poured into a hydrothermal synthesis reactor, heated at 180 ℃ for 12 h. Then cooled to room temperature, washed, filtered and vacuum dried overnight to obtain nitrogen-doped graphene oxide.

[0046] 0.6 g of nitrogen-doped graphene oxide was weighed into 300 mL of ethanol, and after 2 h of vigorous ultrasonic treatment, 0.032 g of RhCl3·3H2O was added, and stirred for 30 min. The mixture was refluxed at 90 ℃ for 24 h under nitrogen protection. After cooling to room temperature, washing, filtering and vacuum drying overnight, a rhodium-loaded nitrogen-doped graphene oxide / porous carbon intermediate was obtained;

[0047] A 150 mL cobalt acetate solution (0.002 mg / mL) was prepared, 0.3 g of rhodium-loaded nitrogen-doped graphene oxide / porous carbon intermediate was added, stirred at room temperature under inert gas protection for 24 h, then filtered, washed and vacuum dried to obtain a black solid, and the black solid was heated at 200 ℃ for 30 min in a 20 volume% H2 / He atmosphere, and after cooling, a nitrogen-doped graphene oxide supported bimetallic catalyst was obtained.

[0048] The content of rhodium was 1.4% by weight based on the weight of the catalyst, as determined by inductively coupled plasma mass spectrometry (ICP).

[0049] Example 2

[0050] The experimental method was the same as in Example 1, except that the weight ratio of graphene oxide dispersion solution to urea was changed to 1:100 when preparing nitrogen-doped graphene oxide, and the rest of the experimental conditions remained unchanged.

[0051] Example 3

[0052] The experimental method is the same as Example 1, wherein the weight ratio of graphene oxide dispersion liquid to urea is changed to 1:50 when preparing nitrogen-doped graphene oxide, and the rest of the experimental conditions remain unchanged.

[0053]

Example 4

[0054] The experimental method is the same as Example 1, wherein the weight ratio of graphene oxide dispersion liquid to urea is changed to 1:10 when preparing nitrogen-doped graphene oxide, and the rest of the experimental conditions remain unchanged.

[0055]

Example 5

[0056] The experimental method is the same as Example 1, wherein the weight ratio of graphene oxide dispersion liquid to urea is changed to 1:300 when preparing nitrogen-doped graphene oxide, and the rest of the experimental conditions remain unchanged.

[0057]

Example 6

[0058] The experimental method is the same as Example 2, wherein the concentration of the prepared cobalt acetate is changed to 0.012 mg / mL, and the rest of the experimental conditions remain unchanged.

[0059]

Example 7

[0060] The experimental method is the same as Example 2, wherein the concentration of the prepared cobalt acetate is changed to 0.006 mg / mL, and the rest of the experimental conditions remain unchanged.

[0061]

Example 8

[0062] The experimental method is the same as Example 2, wherein the concentration of the prepared cobalt acetate is changed to 0.001 mg / mL, and the rest of the experimental conditions remain unchanged.

[0063]

Example 9

[0064] The experimental method is the same as Example 1, wherein the graphene oxide is changed to porous carbon, and the rest of the experimental conditions remain unchanged.

[0065]

Example 10

[0066] The experimental method is the same as Example 2, wherein the concentration of graphene oxide in the graphene oxide dispersion liquid is 1 mg / mL, and the rest of the experimental conditions remain unchanged.

[0067]

Example 11

[0068] The experimental method is the same as Example 2, wherein the concentration of graphene oxide in the graphene oxide dispersion liquid is 2 mg / mL, and the rest of the experimental conditions remain unchanged.

[0069]

Example 12

[0070] The experimental method is the same as Example 2, wherein the concentration of graphene oxide in the graphene oxide dispersion liquid is 6 mg / mL, and the rest of the experimental conditions remain unchanged.

[0071] Example 13

[0072] The experimental method is the same as Example 2, except that the hydrothermal heating at 180℃ for 12h is changed to hydrothermal heating at 120℃ for 36h, and the rest of the experimental conditions remain unchanged.

[0073] Example 14

[0074] The experimental method is the same as Example 1, except that the hydrothermal heating at 180℃ for 12h is changed to hydrothermal heating at 250℃ for 12h, and the rest of the experimental conditions remain unchanged.

[0075] Comparative Example 1

[0076] The experimental method is the same as Example 2, except that the graphene oxide is not doped with nitrogen, and the rest of the experimental conditions remain unchanged.

[0077] Comparative Example 2

[0078] The experimental method is the same as Example 2, except that cobalt loading is not performed, and the rest of the experimental conditions remain unchanged.

[0079] Comparative Example 3

[0080] The experimental method is the same as Example 10, except that the porous carbon is not doped with nitrogen, and the rest of the experimental conditions remain unchanged.

[0081] Comparative Example 4

[0082] The experimental method is the same as Example 10, except that cobalt loading is not performed, and the rest of the experimental conditions remain unchanged.

[0083] Test Example

[0084] The catalysts of Examples 1-14 and Comparative Examples 1-4 are respectively tested, and their activity and selectivity are tested by using a laboratory high-pressure reaction kettle evaluation device. The reaction kettle has a volume of 50mL and is placed in a heating jacket. The determination conditions of the activity and selectivity of the catalysts are shown in Table 1:

[0085] Table 1. Determination conditions of the activity and selectivity of the catalysts

[0086] Reaction temperature Reaction pressure Synthesis gas composition Reaction time Olefin feedstock Solvent 100℃ 4 MPa H2:CO = 1:1 10h 2-octene Toluene

[0087] The activity and selectivity of the catalysts are characterized by olefin conversion rate and aldehyde selectivity, and the calculation formula of the olefin conversion rate and the aldehyde selectivity is as follows:

[0088]

[0089]

[0090] The test method for the molar ratio of cobalt to rhodium in the catalyst, in terms of elements, is inductively coupled plasma mass spectrometry (ICP).

[0091] The test results are shown in Table 2.

[0092] Table 2. Effect of catalyst on the hydroformylation of 2-octene

[0093]

[0094] It can be seen from the above examples and comparative examples that nitrogen doping and cobalt loading on graphene oxide are beneficial to improve the reaction activity and selectivity of the catalyst. The supported bimetallic catalyst of the present application can significantly improve the reaction activity and aldehyde selectivity of the hydroformylation reaction.

[0095] The above only describes the preferred examples of the present application. It should be noted that for those skilled in the art, under the technical inspiration provided by the present application, other equivalent modifications and improvements as the common knowledge in the art can also be made, which should also be considered as the protection scope of the present application.

Claims

1. The application of a supported bimetallic catalyst in the hydroformylation reaction of olefins, characterized in that, The catalyst comprises nitrogen-doped graphene oxide / porous carbon and rhodium and cobalt supported thereon; the molar ratio of cobalt to rhodium is 1:10 to 1:150 by elemental weight. The method for preparing nitrogen-doped graphene oxide / porous carbon includes: mixing a dispersion containing graphene oxide / porous carbon with a nitrogen-containing compound, performing a hydrothermal reaction, and then cooling, washing, filtering, and vacuum drying. The content of graphene oxide / porous carbon is 1.0-6.0 mg per mL of dispersion containing graphene oxide / porous carbon. The nitrogen-containing compound is urea, and the weight ratio of the graphene oxide / porous carbon dispersion to urea is 1:10-300.

2. The application according to claim 1, characterized in that, In the supported bimetallic catalyst, the molar ratio of cobalt to rhodium is 1:25-1:150 (based on elemental composition).

3. The application according to claim 2, characterized in that, The hydrothermal reaction temperature is 100-200℃, and the hydrothermal reaction time is 6-36h.

4. The application according to claim 2, characterized in that, Based on the weight of the catalyst, the rhodium content is 0.1-10% by weight (elemental).

5. The application according to any one of claims 1-4, characterized in that, The method for preparing the supported bimetallic catalyst includes: (1) Nitrogen-doped graphene oxide / porous carbon and solvent are mixed to obtain mixture A; (2) Mix the mixture A with a rhodium-containing compound to obtain mixture B; (3) The mixture B is heated under nitrogen protection and refluxed, then cooled, washed, filtered, and vacuum dried to obtain the rhodium-loaded intermediate; (4) The rhodium-loaded intermediate was impregnated with cobalt acetate solution, filtered, washed, and vacuum dried to obtain a solid; (5) The solid is heated in a mixed atmosphere of H2 / He and then cooled.

6. The application according to claim 5, characterized in that, The solvent volume is 400-600 mL relative to each g of nitrogen-doped graphene oxide / porous carbon; and / or, In mixture B, the content of rhodium compounds, calculated as rhodium element, is 0.01-0.5 mg; and / or, The weight of the rhodium-loaded intermediate relative to each mL of cobalt acetate solution is 0.001-0.003 g; and / or, The concentration of cobalt acetate, calculated as elemental cobalt, is 0.0005-0.03 mg per mL of cobalt acetate solution; and / or, The H2 content in the H2 / He mixed atmosphere is 10-30% by volume; and / or, The heating conditions include: a temperature of 100-200℃ and a time of 10-60 minutes.

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