A nitrogen-doped graphene oxide / porous carbon supported metal catalyst, its preparation method and application

Abstract

This invention discloses a nitrogen-doped graphene oxide / porous carbon supported metal catalyst, its preparation method, and its application. The catalyst preparation method includes: (a) mixing nitrogen-doped graphene oxide / porous carbon with a solvent to obtain mixture A; (b) mixing mixture A with a sodium alginate solution to obtain mixture B; and (c) mixing mixture B with a rhodium-containing compound, followed by washing and drying. The nitrogen-doped graphene oxide / porous carbon supported metal catalyst of this invention achieves a good balance between preparation cost, catalyst activity, and product selectivity. It also exhibits excellent recovery after the reaction, allowing the separated catalyst composition to be recycled, reducing production costs and facilitating industrial production applications.

Description

Technical Field

[0001] This invention belongs to the field of hydroformylation technology, specifically relating to a nitrogen-doped graphene oxide / porous carbon supported metal catalyst, its preparation method, and its application. Background Technology

[0002] Industrially, hydroformylation processes are mainly divided into homogeneous catalysis and two-phase catalysis. Homogeneous catalysis has advantages such as fast reaction rates and high activity, but the product and catalyst need to be separated by distillation. As the carbon chain length increases, the boiling point of the hydroformylation product, the higher carbon aldehyde, increases, requiring higher temperatures for product separation. However, highly active rhodium-based catalysts are easily deactivated at high temperatures; therefore, the high-temperature distillation used in homogeneous catalysis processes leads to the loss of precious metal catalysts, increasing production costs.

[0003] CN111470962A discloses a method for preparing isononanoic acid from mixed isooctenes. The method involves a two-step reaction of hydroformylation and oxidation of mixed isooctenes. In the presence of a novel porous organic polymer-supported rhodium (Rh)-based catalyst, the mixed isooctenes undergo hydroformylation to obtain isonononal, which is then oxidized in an oxidation reactor with oxygen-containing gas under low temperature, low pressure, and catalyst-free conditions to generate isononanoic acid. The specific process of the hydroformylation reaction is as follows: Liquid mixed isooctene is pumped into the reactor using a high-pressure pump, and hydroformylation reaction is carried out with syngas in the presence of a catalyst under certain pressure and temperature to obtain isononanal; the mixed isooctene is composed of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, and the syngas is a mixture of CO and H2; the catalyst is a highly dispersed heterogeneous solid catalyst composed of a main active component and a support, the main active component is Rh, and the support is a porous organic polymer, i.e., a Rh-based catalyst immobilized on a porous organic polymer; the porous organic polymer is a polymer with abundant hierarchical pore structure and large specific surface area, which is polymerized by modifying organic ligands containing P and optional N or S functional elements with vinyl functional groups; the mass fraction of the main active component is 0.01% to 20%, and the remainder is the support.

[0004] While the above methods improve catalyst activity, they cannot simultaneously achieve lower production costs, higher catalyst activity, and product selectivity. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a novel nitrogen-doped graphene oxide / porous carbon supported metal catalyst and its preparation method. This catalyst improves the reactivity and aldehyde selectivity of the hydroformylation reaction by nitrogen doping of graphene oxide / porous carbon and adding sodium alginate during the preparation process. Furthermore, the preparation cost of this invention is low. In addition, as a heterogeneous catalyst, this catalyst exhibits excellent recovery performance after the hydroformylation reaction, and the separated and recovered catalyst composition can be recycled.

[0006] The first aspect of this invention provides a method for preparing a nitrogen-doped graphene oxide / porous carbon supported metal catalyst, comprising:

[0007] (a) Nitrogen-doped graphene oxide / porous carbon is mixed with a solvent to obtain mixture A;

[0008] (b) Mix the mixture A with sodium alginate solution to obtain mixture B;

[0009] (c) Mix the mixture B with the rhodium-containing compound, and then wash and dry it.

[0010] In this invention, "graphene oxide / porous carbon" refers to graphene oxide or porous carbon.

[0011] According to some embodiments of the preparation method of the present invention, the preparation method of the nitrogen-doped graphene oxide / porous carbon includes: mixing a dispersion of graphene oxide / porous carbon with a nitrogen-containing compound, stirring and then carrying out a hydrothermal reaction, followed by cooling, washing, filtering, and vacuum drying.

[0012] According to some embodiments of the preparation method described in this invention, the weight ratio of the graphene oxide / porous carbon dispersion to the nitrogen-containing compound is 1:10-1:300, preferably 1:50-1:300, for example but not limited to: 1:50-1:300, 1:50-1:200, 1:100-1:300, 1:100-1:200, 1:50-1:100.

[0013] In some embodiments of the preparation method described in this invention, the nitrogen-containing compound is urea.

[0014] According to some embodiments of the preparation method described in this invention, the content of graphene oxide / porous carbon is 1.0-6.0 mg per mL of graphene oxide / porous carbon dispersion. That is, the concentration of graphene oxide / porous carbon in the graphene oxide / porous carbon dispersion is 1.0-6.0 mg / mL.

[0015] According to some embodiments of the preparation method described in this invention, the conditions for the hydrothermal reaction include: a temperature of 100-200°C and a time of 6-36 hours.

[0016] According to some embodiments of the preparation method described in this invention, the amount of solvent added is 400-600 mL relative to each g of nitrogen-doped graphene oxide / porous carbon. That is, the amount of nitrogen-doped graphene oxide / porous carbon added is 1 g / 400-600 mL of solvent.

[0017] According to some embodiments of the preparation method of the present invention, the solvent is selected from at least one of water, polar organic solvents, and non-polar organic solvents, preferably water.

[0018] According to some embodiments of the preparation method described in this invention, the content of sodium alginate is 0.005-0.01 g per mL of sodium alginate solution. That is, the concentration of sodium alginate in the sodium alginate solution is 0.005-0.01 g / mL.

[0019] According to some embodiments of the preparation method described in this invention, the volume ratio of mixture A to sodium alginate solution is 300:50-100.

[0020] According to some embodiments of the preparation method described in this invention, the concentration of the rhodium-containing compound is 0.01-0.5 mg / mL, calculated based on the rhodium content.

[0021] According to some embodiments of the preparation method described in this invention, the amount of rhodium-containing compound used satisfies the following: based on the weight of the metal catalyst, the rhodium content, calculated as an element, is 0.1-10% by weight.

[0022] According to some embodiments of the preparation method described in this invention, the rhodium-containing compound is as shown in formula (I):

[0023] Rh(L 1 ) x (L 2 ) y (L 3 ) z Formula (I)

[0024] Among them, L 1 Selected from carbonyl, halogen, acetylacetone, diphenylphosphine, cyclooctadiene, norbornene, and triphenylphosphine; L 2 and L 3 The same or different, each independently selected from hydrogen, carbonyl, chlorine, acetylacetone, diphenylphosphine, cyclooctadiene, norbornene and triphenylphosphine, x is an integer from 1 to 3, y and z are each independently selected from integers from 0 to 4, and x+y+z≤5.

[0025] According to some embodiments of the preparation method of the present invention, the rhodium-containing compound is selected from at least one of rhodium trichloride, rhodium acetylacetone dicarbonyl, rhodium chlorocarbonyl di(triphenylphosphine trisodium trisulfonate), rhodium chlorocarbonyl di(disulfonate triphenylphosphine disodium), rhodium chlorocarbonyl di(triphenylphosphine monosodium sulfonate), and rhodium chlorocarbonyl tri(triphenylphosphine trisodium trisulfonate).

[0026] According to some specific embodiments of the preparation method described in this invention, a method for preparing a nitrogen-doped graphene oxide / porous carbon supported metal catalyst includes, but is not limited to: mixing nitrogen-doped graphene oxide / porous carbon with a solvent and ultrasonically dispersing to obtain a mixture A; mixing mixture A with a sodium alginate solution to obtain a mixture B; adding a rhodium-containing compound to mixture B, stirring overnight under nitrogen protection, and finally washing the solid, filtering and vacuum drying to obtain a uniformly dispersed rhodium-supported nitrogen-doped graphene oxide / porous carbon catalyst.

[0027] A second aspect of the present invention provides a nitrogen-doped graphene oxide / porous carbon supported metal catalyst prepared according to the above-described preparation method.

[0028] According to some embodiments of the catalyst of the present invention, the rhodium content, calculated as an element, is 0.1-10% by weight, based on the weight of the metal catalyst. In the present invention, the rhodium content in the metal catalyst can be changed by adjusting the concentration of the rhodium leaching solution; however, it has been found through measurement that the metal catalyst of the present invention performs better when the rhodium content is in the range of 0.1-10% by weight.

[0029] This third aspect provides the above-described preparation method and the application of the above-described nitrogen-doped graphene oxide / porous carbon supported metal catalyst in the hydroformylation of olefins.

[0030] The beneficial effects of this invention are:

[0031] The nitrogen-doped graphene oxide / porous carbon supported metal catalyst of this invention achieves a good balance between preparation cost, catalyst activity, and product selectivity. It also exhibits excellent recovery after the reaction, allowing the separated catalyst composition to be recycled, reducing production costs and facilitating industrial production applications. Detailed Implementation

[0032] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0033]

Example 1

[0034] A graphene oxide dispersion with a concentration of 4 mg / mL (the graphene content per mL of graphene oxide dispersion is 4 mg) was prepared. Urea was added under vigorous stirring, with a weight ratio of dispersion to urea of ​​1:200. After vigorous stirring at room temperature for 2 hours, the mixture was poured into a hydrothermal synthesis reactor and heated at 180°C for 12 hours. Then, it was cooled to room temperature, washed, filtered, and vacuum dried overnight to obtain nitrogen-doped graphene oxide.

[0035] 0.6 g of nitrogen-doped graphene oxide was weighed and added to 300 mL of ultrapure water. After vigorous sonication for 2 h, 80 mL of sodium alginate solution (0.005 g / mL, meaning 0.005 g of sodium alginate per mL of solution) was added. After stirring for 30 min, 0.032 g of RhCl3·3H2O was added. The mixture was stirred overnight under nitrogen protection at room temperature. Finally, the solid was washed, filtered, and dried under vacuum at 65 °C to obtain the target catalyst.

[0036] The rhodium content was determined by inductively coupled plasma mass spectrometry (ICP) based on the weight of the metal catalyst, with an elemental value of 1.4 wt%.

[0037]

Example 2

[0038] The experimental method was the same as in Example 1, except that the weight ratio of graphene oxide dispersion to urea was changed to 1:100 when preparing nitrogen-doped graphene oxide, while the other experimental conditions remained unchanged.

[0039]

Example 3

[0040] The experimental method was the same as in Example 1, except that the weight ratio of graphene oxide dispersion to urea was changed to 1:50 when preparing nitrogen-doped graphene oxide, while the other experimental conditions remained unchanged.

[0041]

Example 4

[0042] The experimental method was the same as in Example 1, except that the weight ratio of graphene oxide dispersion to urea was changed to 1:10 when preparing nitrogen-doped graphene oxide, while the other experimental conditions remained unchanged.

[0043]

Example 5

[0044] The experimental method was the same as in Example 1, except that the weight ratio of graphene oxide dispersion to urea was changed to 1:300 when preparing nitrogen-doped graphene oxide, while the other experimental conditions remained unchanged.

[0045]

Example 6

[0046] The experimental method was the same as in Example 2, except that the concentration of sodium alginate solution added was 0.006 g / mL, and the other experimental conditions remained unchanged.

[0047]

Example 7

[0048] The experimental method was the same as in Example 2, except that the concentration of sodium alginate solution added was 0.008 g / mL, and the other experimental conditions remained unchanged.

[0049]

Example 8

[0050] The experimental method was the same as in Example 2, except that the concentration of sodium alginate solution added was 0.01 g / mL, and the other experimental conditions remained unchanged.

[0051]

Example 9

[0052] The experimental method was the same as in Example 1, except that the heating at 180°C for 12 hours was changed to heating at 120°C for 36 hours, while the other experimental conditions remained unchanged.

[0053]

Example 10

[0054] The experimental method was the same as in Example 1, except that the heating at 180°C for 12 hours was changed to heating at 250°C for 12 hours, while the other experimental conditions remained unchanged.

[0055]

Example 11

[0056] The experimental method was the same as in Example 1, except that graphene oxide was replaced with porous carbon, nitrogen-doped porous carbon was used, and the other experimental conditions remained unchanged.

[0057] Comparative Example 1

[0058] The experimental method was the same as in Example 2, except that the graphene oxide was not doped with nitrogen, and the other experimental conditions remained unchanged.

[0059] Comparative Example 2

[0060] The experimental method was the same as in Example 2, except that sodium alginate was not added during the catalyst preparation process, and the other experimental conditions remained unchanged.

[0061] Comparative Example 3

[0062] The experimental method was the same as in Example 11, except that the porous carbon was not doped with nitrogen, and the other experimental conditions remained unchanged.

[0063] Comparative Example 4

[0064] The experimental method was the same as in Example 11, except that sodium alginate was not added during the catalyst preparation process, and the other experimental conditions remained unchanged.

[0065] [Test Example]

[0066] The catalysts of Examples 1-11 and Comparative Examples 1-4 were tested respectively, and their activity and selectivity were determined using a laboratory high-pressure reactor evaluation device. The reactor had a volume of 50 mL and was placed in a heating mantle. The conditions for determining the catalyst activity and selectivity are shown in Table 1.

[0067] Table 1. Determination conditions for catalyst activity and selectivity

[0068] reaction temperature Reaction pressure Syngas composition reaction time Olefin feedstock solvent 100℃ 4MPa <![CDATA[H2:CO=1:1]]> 10h 2-Octenene Toluene

[0069] Catalyst activity and selectivity are characterized by olefin conversion and aldehyde selectivity, which are calculated using the following formulas:

[0070]

[0071]

[0072] The test results are shown in Table 2.

[0073] Table 2. Effect of catalysts on the 2-octene hydroformylation reaction

[0074]

[0075] The comparative examples show that nitrogen doping of graphene oxide and the addition of sodium alginate during catalyst preparation both improve the catalyst's reactivity and selectivity. Furthermore, the preparation cost is relatively low.

[0076] The above description is merely a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, based on the technical teachings provided by the present invention and as common knowledge in the field, other equivalent modifications and improvements can be made, and these should also be considered within the scope of protection of the present invention.

Claims

1. The application of a nitrogen-doped graphene oxide / porous carbon supported metal catalyst in the hydroformylation of olefins, wherein the preparation method of the nitrogen-doped graphene oxide / porous carbon supported metal catalyst includes: (a) Nitrogen-doped graphene oxide / porous carbon is mixed with a solvent to obtain mixture A; (b) Mix the mixture A with sodium alginate solution to obtain mixture B; (c) Mix the mixture B with the rhodium-containing compound, and then wash and dry it; The method for preparing nitrogen-doped graphene oxide / porous carbon includes: mixing a dispersion of graphene oxide / porous carbon with a nitrogen-containing compound, stirring and then carrying out a hydrothermal reaction, followed by cooling, washing, filtering, and vacuum drying. The weight ratio of the graphene oxide / porous carbon dispersion to the nitrogen-containing compound is 1:50-1:300, and the content of graphene oxide / porous carbon is 1.0-6.0 mg per mL of the graphene oxide / porous carbon dispersion; the nitrogen-containing compound is urea.

2. The application according to claim 1, characterized in that, The conditions for the hydrothermal reaction include: a temperature of 100-200℃ and a time of 6-36h.

3. The application according to claim 1, characterized in that, The amount of solvent added is 400-600 mL relative to each g of nitrogen-doped graphene oxide / porous carbon; and / or, The solvent is selected from at least one of water, polar organic solvents, and non-polar organic solvents.

4. The application according to claim 3, characterized in that, The solvent is water.

5. The application according to any one of claims 1-4, characterized in that, The sodium alginate content is 0.005-0.01 g per mL of sodium alginate solution; and / or, The volume ratio of mixture A to sodium alginate solution is 300:50-100.

6. The application according to any one of claims 1-4, characterized in that, The concentration of the rhodium-containing compound, calculated as rhodium content, is 0.01-0.5 mg / mL; and / or, The amount of rhodium-containing compounds used should meet the following requirements: based on the weight of the metal catalyst, the rhodium content, calculated as an element, should be 0.1-10% by weight.

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