A method for regenerating phase-change deactivated ruthenium-carbon catalyst

Abstract

This invention belongs to the field of catalyst regeneration technology, specifically relating to a method for regenerating phase-change deactivated ruthenium-carbon catalysts. This invention restricts the internal thermal energy of the carbon material in the phase-change deactivated ruthenium-carbon catalyst under high temperature and pressure, reducing the lattice spacing of the carbon elements and transforming it into graphitized carbon. Then, acid etching with acid and peroxide disperses large catalyst particles into smaller particles. The peroxide reacts with the functional groups on the carbon surface, allowing oxygen to gain electrons and be released, thus re-pore-forming the surface of the regenerated catalyst, increasing its porosity and specific surface area, adding active sites, and improving catalytic efficiency. The acid and peroxide in the etching solution react with ruthenium, transforming large ruthenium particles into small, soluble ruthenium crystals. This allows the agglomerated ruthenium to redisperse and adsorb onto the catalyst surface. Then, a reduction treatment reduces the soluble ruthenium back to ruthenium crystals, which are then loaded onto the catalyst, enhancing the catalytic activity of the regenerated ruthenium-carbon catalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalyst regeneration technology, specifically relating to a method for regenerating a phase-change deactivated ruthenium-carbon catalyst. Background Technology

[0002] Carbon-supported noble metal catalysts can efficiently catalyze the hydrogenation of aromatics, carbon-carbon double bonds, and tranexamic acid reactions. Among various hydrogenation catalysts, carbon-supported nano-noble metal catalysts exhibit higher stability and activity than other supports (such as alumina or molecular sieves) and non-noble metal (copper, nickel, or iron) catalysts. Many carbon materials (such as graphene, carbon nanotubes, and activated carbon) are widely used as supports for various metal catalysts due to their high specific surface area, strong stability, and ease of chemical processing. Furthermore, carbon materials have strong adsorption properties, readily adsorbing metal ions, and also possess excellent reducing properties, capable of reducing metal ions at high temperatures, preventing the prepared metal-supported catalyst from being oxidized and deactivated.

[0003] Studies have shown that combining carbon materials with ruthenium metal exhibits good conversion and selectivity for the hydrogenation of benzene rings, making Ru / C composite catalysts increasingly attractive. Although different carbon supports result in varying catalytic activities, the catalytic activity gradually decreases with increasing reaction cycles until it is completely deactivated.

[0004] The main causes of deactivation of industrial hydrogenation catalysts include coke formation, aggregation of active metal components, and phase changes. Currently, for deactivated catalysts caused by carbon buildup, surface carbon can be removed by carbonization to restore their activity. For example, Chinese patent CN109926105A discloses a method for regenerating hydrogenation catalysts to remove carbon buildup. This method involves preheating the deactivated hydrogenation catalyst and then sequentially subjecting it to staged calcination. After natural cooling, the carbon buildup is removed to obtain a regenerated catalyst. For deactivated catalysts caused by metal aggregation, their activity can be restored by dissolving and reloading. Chinese patent CN110075866A discloses a method for regenerating palladium catalysts to address metal aggregation. This method involves immersing the palladium catalyst in an acidic solution such as hydrochloric acid, which converts large palladium particles into small palladium chloride crystals, which are then reloaded to obtain a regenerated catalyst. However, for deactivated catalysts caused by a decrease in the graphitization degree of the support due to phase changes, there is no suitable regeneration method, and they must be discarded. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for regenerating ruthenium-carbon catalysts that have been deactivated due to phase change, which can efficiently regenerate ruthenium-carbon catalysts that have been deactivated due to reduced graphitization of the support or metal agglomeration caused by phase change.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for regenerating a phase-change deactivated ruthenium-carbon catalyst, comprising the following steps:

[0008] The phase-change deactivated ruthenium-carbon catalyst was sequentially subjected to graphitization, acid etching in an acid etching solution, and reduction to obtain a regenerated ruthenium-carbon catalyst.

[0009] The graphitization treatment is carried out at a temperature of 100–300°C and a pressure of 10–300 MPa.

[0010] The etching solution includes peroxide and acid.

[0011] Preferably, the particle size of the phase-change deactivated ruthenium carbon catalyst is 7–20 nm.

[0012] Preferably, the graphitization treatment time is 1 to 15 hours.

[0013] Preferably, the acid etching treatment time is 12 to 48 hours.

[0014] Preferably, the acid includes one or more of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and perchloric acid.

[0015] Preferably, the peroxide includes one or more of hydrogen peroxide, sodium peroxide, and peracetic acid.

[0016] Preferably, the concentration of acid in the etching solution is 0.5–5 mol / L.

[0017] Preferably, the concentration of peroxide in the acid etching solution is 0.5–5 mol / L.

[0018] Preferably, the graphitization treatment temperature is 150–200°C; the graphitization treatment pressure is 10–150 MPa.

[0019] Preferably, the graphitization treatment time is 5 to 8 hours.

[0020] This invention provides a method for regenerating a phase-change deactivated ruthenium-carbon catalyst, comprising the following steps: sequentially subjecting the phase-change deactivated ruthenium-carbon catalyst to graphitization, acid etching in an acid etching solution, and reduction treatment to obtain a regenerated ruthenium-carbon catalyst; wherein the graphitization treatment is performed at a temperature of 100–300°C and a pressure of 10–300 MPa; and the acid etching solution comprises peroxide and acid.

[0021] This invention utilizes high-temperature and high-pressure graphitization to limit the internal thermal energy of carbon materials in a phase-change deactivated ruthenium-carbon catalyst. High pressure maximizes the direct contact area to improve heat transfer efficiency, thereby accelerating phase change kinetics, increasing mass and heat transfer efficiency, and reducing the lattice spacing of carbon elements, transforming it into graphitized carbon. Then, a highly etchable acid and peroxide are used as an etching solution to etch the graphitized ruthenium-carbon catalyst, dispersing large catalyst particles into smaller ones. Furthermore, the peroxide reacts with functional groups on the carbon surface, releasing oxygen by gaining electrons, thus creating pores in some areas of the activated carbon. This re-pore formation on the surface of the regenerated catalyst further increases its porosity and specific surface area, thereby increasing active sites and improving catalytic efficiency. Furthermore, the acid and peroxide in the etching solution can react with ruthenium, transforming large ruthenium particles into small, soluble ruthenium crystals. This allows the agglomerated ruthenium to redisperse and adsorb onto the catalyst surface. Then, a reduction treatment further reduces the soluble ruthenium to ruthenium crystals, which are then supported on the catalyst, further enhancing the catalytic activity of the regenerated ruthenium-carbon catalyst. The results of the examples show that the regenerated ruthenium-carbon catalyst prepared by the regeneration method provided by this invention exhibits increased graphitization of the carbon material, redispersing agglomerated ruthenium, and uniformly supporting it on graphitized carbon, while also demonstrating excellent catalytic efficiency in the hydrogenation of benzene rings. The regeneration method of this invention can obtain regenerated ruthenium-carbon catalysts in a short time; the method is simple to operate, highly reproducible, and has potential application value. Attached Figure Description

[0022] Figure 1 This is a TEM image of the regenerated ruthenium-carbon catalyst obtained in Example 1;

[0023] Figure 2 TEM image of the phase-change deactivated ruthenium-carbon catalyst used in Example 1;

[0024] Figure 3 The images show the XRD patterns of the regenerated ruthenium-carbon catalyst obtained in Example 1 and the phase-change deactivated ruthenium-carbon catalyst used.

[0025] Figure 4 The diagram shows the composition distribution of the feed solution obtained by catalyzing the hydrogenation reaction of benzene rings using the regenerated ruthenium-carbon catalyst obtained in Example 1 and the phase-change deactivated ruthenium-carbon catalyst. Detailed Implementation

[0026] This invention provides a method for regenerating a phase-change deactivated ruthenium-carbon catalyst, comprising the following steps:

[0027] The phase-change deactivated ruthenium-carbon catalyst was sequentially subjected to graphitization, acid etching in an acid etching solution, and reduction to obtain a regenerated ruthenium-carbon catalyst.

[0028] The graphitization treatment is carried out at a temperature of 100–300°C and a pressure of 10–300 MPa.

[0029] The etching solution includes peroxide and acid.

[0030] Unless otherwise specified, the present invention does not have special requirements on the source of the raw materials used in the preparation, and commercially available products well known to those skilled in the art can be used.

[0031] The present invention graphitizes a phase-change deactivated ruthenium-carbon catalyst to obtain a graphitized ruthenium-carbon catalyst.

[0032] In this invention, the particle size of the phase-change deactivated ruthenium carbon catalyst is preferably 7-20 nm, more preferably 8-10 nm.

[0033] The present invention has found that the phase change deactivation leads to lattice deformation of carbon and metal in ruthenium-carbon catalysts.

[0034] Before graphitization, the present invention preferably cleans and dries the phase-change deactivated ruthenium-carbon catalyst sequentially.

[0035] In this invention, the cleaning solution used for cleaning is preferably a mixture of methanol and water; the volume ratio of methanol to water is not particularly limited in this invention, and can be determined according to actual needs; the number of cleaning cycles is preferably 1 to 3 times, more preferably 2 times; the amount of cleaning solution used is not particularly limited in this invention, and can be selected according to actual needs.

[0036] In this invention, the drying method is preferably drying; the drying equipment is preferably a vacuum oven; the drying temperature is preferably 80-120°C, more preferably 80-100°C; the drying vacuum degree is preferably 100-1000Pa, more preferably 100-200Pa; and the drying time is preferably 1-16 hours, more preferably 6-9 hours.

[0037] In this invention, the temperature of the graphitization treatment is 100-300℃, preferably 150-200℃, and the pressure is 10-300MPa, preferably 10-150MPa; the heat preservation and pressure holding time of the graphitization treatment is preferably 1-15h, more preferably 5-8h; the equipment used for the graphitization treatment is preferably a hot press or a hydraulic press, more preferably a hot press.

[0038] This invention uses high-temperature and high-pressure graphitization to limit the internal thermal energy of carbon materials in ruthenium-carbon catalysts that have undergone phase change deactivation. By maximizing the direct contact area under high pressure, the heat transfer efficiency is improved, thereby accelerating phase change kinetics, increasing mass and heat transfer efficiency, and reducing the lattice spacing of carbon elements, thus transforming them into graphitized carbon.

[0039] After the graphitization treatment, the graphitized ruthenium carbon catalyst is subjected to acid etching in an acid etching solution.

[0040] In this invention, the acid etching solution comprises peroxide and acid; the acid preferably comprises one or more of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and perchloric acid, more preferably sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, or perchloric acid; when the acid is one or more of the above-mentioned types, this invention does not have a special limitation on the ratio of different types of acid, and any ratio is acceptable; the peroxide preferably comprises one or more of hydrogen peroxide, sodium peroxide, and peracetic acid, more preferably hydrogen peroxide, sodium peroxide, or peracetic acid; when the peroxide is one or more of the above-mentioned types, this invention does not have a special limitation on the ratio of different types of peroxide, and any ratio is acceptable; the concentration of acid in the acid etching solution is preferably 0.5–5 mol / L, more preferably 1–2 mol / L; the concentration of peroxide in the acid etching solution is 0.5–5 mol / L, more preferably 1–3 mol / L; the acid etching process preferably involves immersing the graphitized ruthenium carbon catalyst in the acid etching agent; the acid etching time is preferably 12–48 h, more preferably 20–25 h.

[0041] This invention employs highly etching-capable acids and peroxides as etching agents to etch graphitized ruthenium-carbon catalysts, dispersing large catalyst particles into smaller ones. Furthermore, the peroxides react with functional groups on the carbon surface, releasing oxygen by gaining electrons. This creates pores in some areas of the activated carbon, re-forming pores on the surface of the regenerated catalyst, further increasing its porosity and specific surface area, thereby increasing active sites and improving catalytic efficiency. In addition, the acid and peroxides in the etching agent can react with ruthenium, transforming large ruthenium metal particles into small, soluble ruthenium crystals, redispersing the agglomerated ruthenium. Subsequent reduction treatment reduces the soluble ruthenium adsorbed on the catalyst surface into ruthenium crystals, which are then supported on the regenerated catalyst, further enhancing the catalytic activity of the regenerated ruthenium-carbon catalyst.

[0042] After the acid etching treatment, the present invention preferably neutralizes the acid etchant soaked with graphitized ruthenium carbon catalyst to a pH value of 6.5-7.5, and then continues to soak for 12-24 hours, followed by filtration to obtain the acidified ruthenium carbon catalyst.

[0043] In this invention, the neutralization solution is preferably an aqueous solution of potassium hydroxide; the concentration of the potassium hydroxide aqueous solution is preferably 0.5–3 mol / L, more preferably 1–2 mol / L. This invention does not impose any particular limitation on the filtration process; any filtration process well known in the art can be used.

[0044] After obtaining the acidified ruthenium carbon catalyst, the present invention performs a reduction treatment on the acidified ruthenium carbon catalyst to obtain a regenerated ruthenium carbon catalyst.

[0045] Before the reduction process, the present invention preferably cleans and dries the acidified ruthenium carbon catalyst in sequence.

[0046] In this invention, the cleaning solution is preferably water; the cleaning process is not particularly limited and can be selected according to actual conditions; the drying temperature is preferably 80-120℃, more preferably 80-100℃; the drying vacuum degree is preferably 100-1000Pa, more preferably 100-200Pa; the drying time is preferably 1-16h, more preferably 6-9h.

[0047] In this invention, the temperature of the reduction treatment is preferably 600-900℃, more preferably 700-800℃, and the holding time is preferably 5-12h, more preferably 6-8h.

[0048] This invention reduces soluble ruthenium adsorbed on the catalyst surface to ruthenium crystals, which are then loaded onto the catalyst surface through a reduction treatment.

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] 100g of phase-change deactivated ruthenium-carbon catalyst (particle size 9nm) was washed twice with a mixture of methanol and water, then placed in a vacuum oven (vacuum degree 150Pa) and dried at 80℃ for 8h. The dried phase-change deactivated ruthenium-carbon catalyst was then graphitized by pressing at 180℃ and 100MPa for 5h in a hot press. The graphitized ruthenium-carbon catalyst was then soaked in 1.5mol / L nitric acid solution (containing 1mol / L peracetic acid) for 24h, and the pH was adjusted to neutral with 1mol / L potassium hydroxide aqueous solution. After soaking for another 24h, the solution was filtered, washed with water, and placed in a vacuum oven (vacuum degree 150Pa) and dried at 80℃ for 8h. Finally, it was reduced at 700℃ for 8h to obtain the regenerated ruthenium-carbon catalyst.

[0052] Example 2

[0053] 150g of phase-change deactivated ruthenium-carbon catalyst (particle size 9nm) was washed twice with a mixture of methanol and water, then placed in a vacuum oven (vacuum degree 150Pa) and dried at 80℃ for 8h. The dried phase-change deactivated ruthenium-carbon catalyst was then graphitized by pressing at 180℃ and 150MPa for 1h using a hot press. The graphitized ruthenium-carbon catalyst was then soaked in a 1.5mol / L sulfuric acid solution (containing 1.5mol / L peracetic acid) for 24h, and the pH was adjusted to neutral with a 1mol / L potassium hydroxide aqueous solution. After soaking for another 12h, the solution was filtered, washed with water, and placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. Finally, it was reduced at 700℃ for 8h to obtain the regenerated ruthenium-carbon catalyst.

[0054] Example 3

[0055] 50g of phase-change deactivated ruthenium-carbon catalyst (particle size 9nm) was washed twice with a mixture of methanol and water, then placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. The dried phase-change deactivated ruthenium-carbon catalyst was then graphitized by pressing at 180℃ and 150MPa for 5h in a hot press. The graphitized ruthenium-carbon catalyst was then soaked in a 1.5mol / L phosphoric acid solution (containing 1mol / L sodium peroxide) for 24h, and the pH was adjusted to neutral with a 1mol / L potassium hydroxide aqueous solution. After soaking for another 24h, the solution was filtered, washed with water, and placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. Finally, it was reduced at 700℃ for 8h to obtain the regenerated ruthenium-carbon catalyst.

[0056] Example 4

[0057] 200g of phase-change deactivated ruthenium-carbon catalyst (particle size 9nm) was washed twice with a mixture of methanol and water, then placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. The dried phase-change deactivated ruthenium-carbon catalyst was then graphitized by pressing at 180℃ and 150MPa for 10h in a hot press. The graphitized ruthenium-carbon catalyst was then soaked in 1.5mol / L hydrochloric acid solution (containing 0.5mol / L hydrogen peroxide) for 24h, and the pH was adjusted to neutral with 1mol / L potassium hydroxide aqueous solution. After soaking for another 24h, the solution was filtered, washed with water, and placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. Finally, it was reduced at 700℃ for 8h to obtain the regenerated ruthenium-carbon catalyst.

[0058] Example 5

[0059] 120g of phase-change deactivated ruthenium-carbon catalyst (particle size 9nm) was washed twice with a mixture of methanol and water, then placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. The dried phase-change deactivated ruthenium-carbon catalyst was then graphitized by pressing at 180℃ and 150MPa for 12h in a hot press. The graphitized ruthenium-carbon catalyst was then soaked in a 1mol / L perchloric acid solution (containing 1ml / L hydrogen peroxide) for 24h, and the pH was adjusted to neutral with a 1mol / L potassium hydroxide aqueous solution. After soaking for another 13h, the catalyst was filtered, washed with water, and placed in a vacuum oven (vacuum degree 100Pa) and dried at 80℃ for 8h. Finally, it was reduced at 700℃ for 8h to obtain the regenerated ruthenium-carbon catalyst.

[0060] Performance testing

[0061] (1) The regenerated ruthenium-carbon catalyst obtained in Example 1 was tested at 20 nm using a HAADF electron microscope. The results are as follows: Figure 1 As shown.

[0062] Depend on Figure 1 It is known that the ruthenium particles in the regenerated ruthenium carbon catalyst obtained by the present invention have a particle size of 2-4 nm, and the ruthenium particles loaded on the catalyst have uniform morphology, uniform size, and uniform dispersion.

[0063] (2) The phase-change deactivated ruthenium-carbon catalyst used in Example 1 was tested at 100 nm using transmission electron microscopy, and the results are as follows: Figure 2 As shown.

[0064] Depend on Figure 2 It is known that the particle size of ruthenium particles in the waste ruthenium carbon catalyst used in this invention is 8-10 nm, and obvious agglomeration can be observed.

[0065] (3) X-ray diffraction tests were performed on the regenerated ruthenium-carbon catalyst and the spent ruthenium-carbon catalyst obtained in Example 1. The results are as follows: Figure 3 As shown.

[0066] Depend on Figure 3 It can be seen that after the regeneration treatment of the waste ruthenium carbon catalyst by the present invention, the carbon peak is significantly shifted to the right, which indicates that the degree of graphitization is increased. The corresponding diffraction peak of ruthenium is broadened, indicating that compared with the deactivated catalyst, the grain size of the regenerated ruthenium carbon catalyst is reduced and the agglomerated ruthenium is redispersed.

[0067] (4) The regenerated ruthenium-carbon catalyst obtained in Example 1 and the spent ruthenium-carbon catalyst were respectively subjected to catalytic benzene ring hydrogenation reaction experiments. The reaction conditions were as follows: 0.1% of the regenerated ruthenium-carbon catalyst was added to a feed solution containing 10% benzene by mass, and the reaction was carried out in a batch reactor at a reaction temperature of 150°C and a reaction pressure of 5 MPa for 4 hours to obtain the reaction solution. The composition of the reaction solution was detected, and the catalytic effect of the regenerated ruthenium-carbon catalyst was evaluated by the peak elution of gas chromatography. The results are as follows. Figure 4 As shown, blue represents unreacted raw materials, yellow represents cis products, orange represents trans products, and light orange represents byproducts.

[0068] Depend on Figure 4 It can be seen that the regenerated ruthenium carbon catalyst obtained by the regeneration method of the present invention can effectively catalyze the hydrogenation reaction of benzene rings compared with the waste ruthenium carbon catalyst, with only 7% unreacted raw material, while the unreacted raw material obtained by using the waste ruthenium carbon catalyst is 83%.

[0069] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for regenerating a phase-change deactivated ruthenium-carbon catalyst, characterized in that, Includes the following steps: The phase-change deactivated ruthenium-carbon catalyst was sequentially subjected to graphitization, acid etching in an acid etching solution, and reduction to obtain a regenerated ruthenium-carbon catalyst. The graphitization treatment is carried out at a temperature of 100–300°C and a pressure of 10–300 MPa. The etching solution includes peroxide and acid.

2. The regeneration method according to claim 1, characterized in that, The phase-change deactivated ruthenium-carbon catalyst has a particle size of 7–20 nm.

3. The regeneration method according to claim 1, characterized in that, The heat preservation and pressure holding time for the graphitization treatment is 1 to 15 hours.

4. The regeneration method according to claim 1, characterized in that, The acid etching process takes 12 to 48 hours.

5. The regeneration method according to claim 1, characterized in that, The acid includes one or more of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and perchloric acid.

6. The regeneration method according to claim 1, characterized in that, The peroxide includes one or more of hydrogen peroxide, sodium peroxide, and peracetic acid.

7. The regeneration method according to claim 1 or 5, characterized in that, The concentration of acid in the etching solution is 0.5–5 mol / L.

8. The regeneration method according to claim 1 or 6, characterized in that, The concentration of peroxide in the acid etching solution is 0.5–5 mol / L.

9. The regeneration method according to claim 1, characterized in that, The graphitization treatment temperature is 150–200°C; the graphitization treatment pressure is 10–150 MPa.

10. The regeneration method according to claim 1 or 9, characterized in that, The graphitization process takes 5 to 8 hours.

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