A method for enriching and recovering rhodium from a rhodium-containing synthesis inactivation solution

Abstract

This application provides a method for enriching and recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis. In this method, the rhodium is enriched and concentrated into the oil-phase organic matter through a mixed reaction of the carbonyl synthesis-deactivated rhodium-containing solution and an alkaline solution, significantly reducing the energy consumption required for rhodium enrichment and concentration, and also significantly reducing the burden on subsequent recovery processing. During the rhodium recovery process, the programmed temperature roasting method allows for more precise and effective control of the reaction process, preventing boiling over and physical splashing loss of rhodium, thus improving the rhodium recovery rate. During the oxidative roasting process after mixing the rhodium-containing solid with the alkaline solution, phosphorus species in the rhodium-containing solid react with organic carboxylic acid alkaline salts to generate phosphates such as sodium phosphate or potassium phosphate, thereby ensuring that rhodium exists in oxide or elemental form, avoiding the generation of harmful phosphorus oxides during roasting. The rhodium-enriched product recovered by the method provided in this application has a rhodium content of 61.75-66.53% and a recovery rate of 96.4-97.5%.

Description

Technical Field

[0001] This invention belongs to the field of precious metal resource recycling technology, and relates to a method for enriching and recovering rhodium from carbonyl synthesis deactivated rhodium-containing solutions. Background Technology

[0002] Homogeneous rhodium organic complex catalysts possess advantages such as high catalytic activity and good selectivity, serving as core catalytically active components in catalytic reactions such as catalytic hydrogenation and olefin hydroformylation, and have important and wide-ranging applications. The rhodium-containing organic wastewater generated after the deactivation of rhodium homogeneous organic complex catalysts has a low rhodium content, only a few hundred ppm, and its composition mainly includes: triphenylphosphine, triphenylphosphine oxide, n-butyraldehyde, isobutyraldehyde, n-butanol, isobutanol, octenal, octanol, butyric acid and other organic acids, butyraldehyde trimers / pentamelis and other butyraldehyde polymers, other high-boiling-point organic condensation polymers, rhodium-phosphine complexes, etc., making its composition complex. Rhodium is a rare platinum group metal, scarce in the Earth's crust, difficult to mine and extract, and expensive. Therefore, recovering rhodium from spent catalysts has significant economic and social value.

[0003] Currently, rhodium recovery methods can be mainly divided into pyrometallurgical and hydrometallurgical processes. Pyrometallurgical methods, which involve incineration to recover rhodium, are commonly used in industrial production. For example, patent CN101362207A discloses a method of incinerating and ashing rhodium at 600-1000℃, followed by high-temperature melting to obtain soluble rhodium salts for rhodium recovery, achieving a rhodium recovery rate of over 87%. Patent CN1414125A discloses a method using alkali metal or alkaline earth metal carbonates as additives, added to the residual rhodium catalyst from a carbonyl synthesis reaction, and incinerated at 650-700℃. The remaining residue then reacts with molten alkali metal acid sulfates to generate soluble rhodium salts, which are then separated using electrolysis, achieving a final rhodium recovery rate of over 90%. However, these methods require the addition of large amounts of alkaline compounds as auxiliaries, resulting in high impurity levels in the generated rhodium ash, which affects the final yield. CN107879382 A discloses a method for recovering rhodium from incinerated rhodium slag to prepare rhodium chloride. This method first involves aerobic high-temperature roasting of spent catalyst rhodium slag with incompletely removed organic matter at 950-1000℃ to completely remove the organic matter, yielding rhodium ash. While this method can improve the rhodium yield, the reaction temperature is too high, requiring sophisticated industrial operation, posing certain safety risks, and negatively impacting production stability. Furthermore, due to considerations of rhodium overburning, some organic matter cannot be removed through incineration, making subsequent processing complex.

[0004] Wet processing typically involves distilling and concentrating the spent rhodium catalyst. This process not only consumes a large amount of energy but also requires the organic matter to react with a strong oxidant, posing significant safety risks. For example, patent CN 112481494A discloses a method for recovering rhodium from spent rhodium catalyst residue. This method first distills the spent rhodium catalyst residue from a carbonyl synthesis reaction to obtain rhodium-containing residue; then calcines the rhodium-containing residue to obtain rhodium ash; finally, it dissolves the rhodium ash in hydrochloric acid and hydrogen peroxide solution to obtain a crude rhodium chloroaluminate solution; and finally, it concentrates the crude rhodium chloroaluminate solution to obtain a final rhodium chloroaluminate solution. Patent CN 121852714 A discloses a method for recovering rhodium from organic residues containing triphenylphosphine / phosphine oxide. The method first involves vacuum distillation of the organic residue containing triphenylphosphine / phosphine oxide to remove volatile components until the residue meets the requirements for subsequent process feed. The light components are collected and stored separately. Then, an acidic medium is added to the organic phase after the light components have been removed, and the mixture is stirred and heated to introduce an oxidant to carry out an oxidation-complexation reaction. The reaction conditions are maintained until the reaction is complete. After standing and phase separation, the aqueous phase containing rhodium complex ions is collected.

[0005] In summary, among the current domestic and international processes for recovering rhodium from spent rhodium catalysts, direct oxidation and incineration result in significant metal losses, low rhodium recovery rates, or excessively high roasting temperatures, placing high demands on industrial production operations and posing certain safety risks. Wet processes, on the other hand, generally require pre-distillation, consume substantial energy, and involve reactions between organic matter and strong oxidizers, resulting in violent, flammable, and explosive reactions, highlighting significant safety concerns. Summary of the Invention

[0006] The purpose of this invention is to provide a method for enriching and recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, so as to solve the problem of high energy consumption in wet rhodium recovery.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this application provides a method for enriching rhodium from a rhodium-containing solution deactivated by carbonyl synthesis. The method includes: mixing and reacting the rhodium-containing solution deactivated by carbonyl synthesis with an alkaline solution, allowing it to stand, and then obtaining a rhodium-rich mixture and an alkaline mixture.

[0008] Secondly, this application provides a method for recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, the method comprising: The rhodium-rich mixture obtained in the first aspect is mixed with biochar powder and calcined under a programmed temperature rise under an inert gas to obtain a rhodium-containing solid. The rhodium-containing solid is stirred and mixed with the alkaline mixture obtained from the first aspect, dried, oxidized and roasted, washed, and dried again to obtain a rhodium-enriched product.

[0009] The present invention has the following beneficial effects: (1) In this application, the rhodium-containing solution deactivated by carbonyl synthesis and the alkaline solution can be mixed and reacted to enrich and concentrate rhodium into the oil phase organic matter, which greatly reduces the energy consumption required for rhodium enrichment and concentration, and at the same time significantly reduces the burden of subsequent recycling and treatment.

[0010] (2) In this application, the addition of biochar powder can improve the recovery rate of rhodium by adsorbing rhodium in the roasting process of rhodium-rich mixture.

[0011] (3) In this application, the rhodium-rich mixture is roasted using a programmed temperature rise method. This method can more accurately and effectively control the reaction process, prevent boiling and spraying, and prevent physical splashing loss of rhodium, thereby improving the rhodium recovery rate.

[0012] (4) In this application, the rhodium-containing solid is mixed with the alkaline mixture generated during the rhodium enrichment and concentration process, which reduces the use of sodium carbonate and improves the utilization rate of the alkaline solution.

[0013] (5) In this application, during the oxidative roasting process after the rhodium-containing solid is mixed with the alkaline mixture, the phosphorus species in the rhodium-containing solid react with organic carboxylic acid alkaline salts to generate sodium phosphate or potassium phosphate, thereby allowing rhodium to exist in the form of oxides or elements, thus avoiding the generation of harmful phosphorus oxides during roasting. Detailed Implementation

[0014] In a first aspect, this application provides a method for enriching rhodium from a rhodium-containing solution deactivated by carbonyl synthesis. The method includes: mixing and reacting the rhodium-containing solution deactivated by carbonyl synthesis with an alkaline solution, allowing it to stand, and then obtaining a rhodium-rich mixture and an alkaline mixture.

[0015] The rhodium-containing solution deactivated by carbonyl synthesis was mixed with an alkaline solution of 15-50% by mass at a ratio of 1:0.1-1:0.5 and reacted at 5-60℃ for 0.5-12 hours to enrich and concentrate rhodium. After the reaction was completed, the mixture was allowed to stand, and the reaction product separated into two phases: an oil phase, which was a rhodium-rich mixture, and an aqueous phase, which was an alkaline mixture.

[0016] In this application, the rhodium-containing solution used for carbonyl synthesis deactivation is a homogeneous rhodium-phosphine catalyst waste liquid deactivated after the carbonyl synthesis reaction of olefins such as propylene. Its main components include: rhodium-phosphine complexes, phosphorus-containing substances such as triphenylphosphine and triphenylphosphine oxide, aldehydes such as n-butyraldehyde, isobutyraldehyde, and octenal, organic alcohols such as n-butanol, isobutanol, and butyric acid, butyraldehyde trimers / pentamelis and other butyraldehyde polymers, and other high-boiling-point organic condensation polymers. The alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

[0017] When the rhodium-containing solution for carbonyl synthesis deactivation is mixed with an alkaline solution, various reactions occur, mainly including: (1) Carbonyl synthesis deactivation: The organic carboxylic acids contained in the rhodium-containing solution can undergo a neutralization reaction with the alkaline solution to generate the corresponding organic carboxylic acid alkaline salts; (2) During the mixing process, aldehydes are oxidized by air to produce the corresponding carboxylic acid; in the presence of alkaline solution, the generated carboxylic acid immediately undergoes a neutralization reaction with the alkaline solution to produce the corresponding carboxylate, such as sodium butyrate or potassium butyrate. (3) The esters or hemiacetals in the butyraldehyde polymer undergo saponification under strong alkaline conditions to generate the corresponding carboxylic acid salts.

[0018] Therefore, after the carbonyl synthesis deactivation rhodium-containing solution reacts with the alkaline solution, it will separate into an oil phase and an aqueous phase. The upper oil phase is a rhodium-rich mixture containing a large amount of phosphorus, and its main components are: rhodium-phosphine complex, triphenylphosphine, triphenylphosphine oxide, organic heavy oil and hydrocarbon organic solvents; the lower aqueous phase is an alkaline mixture, and its main components are: organic carboxylic acid alkaline salts and excess alkaline solution.

[0019] Compared to the traditional method of distillation to enrich rhodium, the method of enriching rhodium by reacting the deactivated rhodium-containing solution with alkaline solution through carbonyl synthesis can concentrate rhodium into the oil phase, greatly reducing the energy consumption required for rhodium enrichment and concentration, and significantly reducing the burden of subsequent recovery and treatment.

[0020] Secondly, this application provides a method for recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, the method comprising: S01: The rhodium-rich mixture obtained in the first aspect is mixed with biochar powder and calcined under a programmed temperature rise under an inert gas to obtain a rhodium-containing solid.

[0021] The rhodium-rich mixture obtained above was mixed with biochar powder at a mass ratio of 1:0.1-1:0.5 and then placed in a closed horizontal tube furnace. An inert gas with a flow rate of 20-200 mL / min was introduced into the horizontal tube furnace, and the furnace was heated and calcined according to the program. Rhodium entered the solid component, and a rhodium-containing solid was obtained.

[0022] In this application, biomass charcoal powder is added during the roasting process of the rhodium-rich mixture. The addition of biomass charcoal powder can improve the rhodium recovery rate through adsorption. Preferably, the biomass charcoal powder includes one or more of bamboo charcoal powder, wood charcoal powder, and straw charcoal powder, and the inert gas is nitrogen, argon, or helium.

[0023] In this application, the rhodium-rich mixture is calcined using a programmed temperature increase method. This calcination method allows for more precise and effective control of the reaction process, preventing boiling over, spraying, and physical splashing loss of rhodium. The programmed temperature calcination in this application includes: At room temperature - 250℃, the heating rate is 2-5℃ / min; before heating to 250℃, constant temperature roasting is carried out at 50℃ for 60-120min, and constant temperature roasting is carried out at 250℃ for 60-120min. 250-550℃, heating rate is 1-3℃ / min, before heating to 550℃, constant temperature roasting at 100℃ for 60-120min, and constant temperature roasting at 550℃ for 60-120min. 550℃ - final temperature, heating rate of 1-2℃ / min, and constant temperature calcination at the final temperature for 120-240min, with a final temperature of 600-750℃.

[0024] S02: The rhodium-containing solid is stirred and mixed with the alkaline mixture obtained from the enrichment in the first aspect, dried, oxidized and roasted, washed and dried to obtain the rhodium-enriched product.

[0025] Rhodium-containing solids are pulverized to a particle size of less than 20 mesh and then mixed with the alkaline mixture obtained from the enrichment process in the first step at a mass-to-volume ratio of 1:3-1:10, stirred for 2-12 hours, and dried at 70-120℃ for 6-24 hours to form an alkali-loaded rhodium-containing solid. The alkali-loaded rhodium-containing solid is then oxidatively roasted at 500-650℃ for 2-8 hours to allow phosphorus species in the rhodium-containing solid to react with organic carboxylic acid base salts to form phosphates such as sodium phosphate or potassium phosphate. This ensures that rhodium exists in oxide or elemental form, avoiding the formation of harmful phosphorus oxides during roasting, ultimately yielding the oxidative roasting product. This oxidative roasting product is then mixed with deionized water at a mass ratio of 1:20-1:200 for 0.5-2 hours to wash the oxidative roasting product with deionized water, removing water-soluble salts such as sodium phosphate or potassium phosphate. After washing, the product is filtered and dried at 110-130℃ for 2-10 hours to obtain the rhodium concentrate.

[0026] The technical solution of the present invention will be further explained and illustrated below through specific embodiments. In the following embodiments and comparative examples, the concentration of rhodium in the carbonyl synthesis deactivation rhodium-containing solution is 628 mg / kg.

[0027] Example 1 This application provides a method for enriching rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, the method comprising: 500g of carbonyl synthesis deactivated rhodium-containing solution was mixed with 115.91g of 25% sodium hydroxide aqueous solution and stirred. The mixture was reacted at room temperature for 4 hours and then allowed to stand to obtain 346g of rhodium-rich mixture and 269.91g of alkaline mixture.

[0028] Example 2 This application provides a method for enriching rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, the method comprising: 500g of carbonyl synthesis deactivated rhodium-containing solution was mixed with 185.02g of 32% sodium hydroxide aqueous solution and reacted at 40℃ for 6h. After standing, 261g of rhodium-rich mixture and 424.02g of alkaline mixture were obtained.

[0029] Example 3 This application provides a method for enriching rhodium from a rhodium-containing solution deactivated by carbonyl synthesis, the method comprising: 500g of carbonyl synthesis deactivated rhodium-containing solution was mixed with 157.1g of 30% potassium hydroxide aqueous solution and reacted at 35℃ for 8h. After standing, 306.78g of rhodium-rich mixture and 350.32g of alkaline mixture were obtained.

[0030] Example 4 This application provides a method for recovering rhodium from a rhodium-containing solution deactivated during carbonyl synthesis, the method comprising: S401: The rhodium-rich mixture from Example 1 was mixed with 35g of charcoal powder and placed in a sealed horizontal tube furnace. Nitrogen gas at a flow rate of 60mL / min was introduced into the horizontal tube furnace, and the mixture was calcined according to a programmed temperature rise. Rhodium was incorporated into the solid component, resulting in a rhodium-containing solid. The programmed temperature rise calcination included: room temperature - 250℃, with a heating rate of 4℃ / min; calcination at a constant temperature of 50℃ for 600min before reaching 250℃, followed by calcination at 250℃ for 60min; 250-550℃, with a heating rate of 3℃ / min, with calcination at a constant temperature of 100℃ for 60min before reaching 550℃, followed by calcination at 550℃ for 60min; 550-700℃, with a heating rate of 2℃ / min, followed by calcination at 700℃ for 180min.

[0031] S402: The rhodium-containing solid was pulverized to a particle size of less than 20 mesh, then mixed and stirred with the alkaline mixture from Example 1 for 3 hours, and dried at 100°C for 8 hours to form an alkali-loaded rhodium-containing solid. The alkali-loaded rhodium-containing solid was oxidized and calcined at 550°C for 2 hours to obtain an oxidized and calcined product. This oxidized and calcined product was added to 500 mL of deionized water, stirred and mixed for 2 hours, filtered, and dried at 120°C for 6 hours to obtain 0.49 g of rhodium-enriched material.

[0032] Example 5 This application provides a method for recovering rhodium from a rhodium-containing solution deactivated during carbonyl synthesis, the method comprising: S501: The rhodium-rich mixture from Example 2 was mixed with 40g of straw charcoal powder and placed in a closed horizontal tube furnace. Argon gas at a flow rate of 40mL / min was introduced into the horizontal tube furnace, and the mixture was calcined according to a programmed temperature rise. Rhodium entered the solid component, resulting in a rhodium-containing solid. The programmed temperature rise calcination included: room temperature - 250℃, with a heating rate of 4℃ / min; calcination at 50℃ for 60min before reaching 250℃, followed by calcination at 250℃ for another 60min; 250-550℃, with a heating rate of 2℃ / min, with calcination at 100℃ for 60min before reaching 550℃, followed by calcination at 550℃ for another 60min; 550-650℃, with a heating rate of 1℃ / min, followed by calcination at 650℃ for 120min.

[0033] S502: The rhodium-containing solid was pulverized to a particle size of less than 20 mesh, then mixed and stirred with the alkaline mixture from Example 2 for 7 hours, and dried at 90°C for 12 hours to form an alkali-loaded rhodium-containing solid. The alkali-loaded rhodium-containing solid was oxidized and calcined at 650°C for 5 hours to obtain an oxidized and calcined product. This oxidized and calcined product was added to 500 mL of deionized water, stirred and mixed for 2 hours, filtered, and dried at 110°C for 10 hours to obtain 0.46 g of rhodium-enriched material.

[0034] Example 6 This application provides a method for recovering rhodium from a rhodium-containing solution deactivated during carbonyl synthesis, the method comprising: S601: The rhodium-rich mixture from Example 3 was mixed with 53g of bamboo charcoal powder and placed in a sealed horizontal tube furnace. Helium gas at a flow rate of 50mL / min was introduced into the horizontal tube furnace, and the mixture was calcined according to a programmed temperature rise. Rhodium entered the solid component, resulting in a rhodium-containing solid. The programmed temperature rise calcination included: room temperature - 250℃, with a heating rate of 3℃ / min; before reaching 250℃, constant temperature calcination was performed at 50℃ for 120min, followed by constant temperature calcination at 250℃ for 120min; 250-550℃, with a heating rate of 2℃ / min, before reaching 550℃, constant temperature calcination was performed at 100℃ for 60min, followed by constant temperature calcination at 550℃ for 60min; 550-750℃, with a heating rate of 1℃ / min, followed by constant temperature calcination at 750℃ for 120min.

[0035] S602: The rhodium-containing solid was pulverized to a particle size of less than 20 mesh, then mixed and stirred with the alkaline mixture from Example 3 for 5 hours, and dried at 110°C for 5 hours to form an alkali-loaded rhodium-containing solid. The alkali-loaded rhodium-containing solid was oxidized and calcined at 620°C for 3 hours to obtain an oxidized and calcined product. This oxidized and calcined product was added to 500 mL of deionized water, stirred and mixed for 2 hours, filtered, and dried at 130°C for 4 hours to obtain 0.47 g of rhodium-enriched material.

[0036] Comparative Example 1 This application provides a comparative example of a method for recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis. The method is the same as in Example 4, except that the rhodium-rich mixture is obtained by distillation of 500g of rhodium-containing solution deactivated by carbonyl synthesis, and the mass of the rhodium-rich concentrate is 0.48g.

[0037] Comparative Example 2 This application provides a comparative example of a method for recovering rhodium from a rhodium-containing solution deactivated by carbonyl synthesis. The method is the same as in Example 4, except that the rhodium-rich mixture is obtained by distillation of 500g of rhodium-containing solution deactivated by carbonyl synthesis, and 269.91g of sodium carbonate aqueous solution is added to the rhodium-rich mixture and stirred. The mass of sodium carbonate is 5g and the mass of rhodium concentrate is 0.47g.

[0038] The rhodium content of the rhodium enrichments prepared in Examples 4-6 and Comparative Examples 1 and 2 was analyzed, and the rhodium recovery rate was calculated, as shown in Table 1.

[0039] Table 1: Rhodium content and rhodium recovery rate As shown in Table 1, the rhodium content of the rhodium-enriched products recovered in Examples 4-6 of this application was 61.75-66.53%, and the recovery rate was 96.4-97.5%. In contrast, the rhodium content of the rhodium-enriched products obtained by distillation of the deactivated rhodium-containing solution from carbonyl synthesis was 61.05%, and the recovery rate was 93.3%, both of which were lower than the rhodium-enriched products recovered in Examples 4-6.

[0040] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A process for the enrichment of rhodium from a rhodium-containing synthesis-inactive carbonyl solution, characterized in that, include: After the carbonyl synthesis deactivation rhodium-containing solution is mixed with an alkaline solution and allowed to stand, a rhodium-rich mixture and an alkaline mixture are obtained.

2. The method of claim 1, wherein the method is characterized by, The mass ratio of the rhodium-containing solution for carbonyl synthesis deactivation to the alkaline solution is 1:0.1-1:0.5, the reaction temperature is 5-60℃, and the reaction time is 0.5-12h.

3. The method of claim 1, wherein the method further comprises, The alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the mass concentration of the alkaline solution is 15-50%.

4. A process for the recovery of rhodium from a rhodium-containing synthesis inactivation solution of carbonyls, characterized in that, include: The rhodium-rich mixture obtained by the method described in any one of claims 1-3 is mixed with biochar powder and calcined under a programmed temperature rise under an inert gas to obtain a rhodium-containing solid. The rhodium-containing solid is stirred and mixed with the alkaline mixture obtained by the method described in any one of claims 1-3, dried, oxidized and roasted, washed, and dried again to obtain a rhodium-enriched product.

5. The method of recovering rhodium from a rhodium-containing solution inactivated from carbonylation synthesis according to claim 4, characterized in that, The mass ratio of the rhodium-rich mixture to biochar powder is 1:0.1-1:0.5, and the mass ratio of the rhodium-containing solid to the alkaline mixture is 1:3-1:

10.

6. The method of recovering rhodium from a rhodium-containing solution inactivated from carbonylation synthesis according to claim 4, characterized in that, The inert gas is nitrogen, argon, or helium, with a flow rate of 20-200 mL / min; the biomass charcoal powder includes one or more of bamboo charcoal powder, wood charcoal powder, and straw charcoal powder.

7. The method of recovering rhodium from a rhodium-containing solution inactivated from carbonylation synthesis according to claim 4, characterized in that, The programmed heating and roasting process includes: At room temperature - 250℃, the heating rate is 2-5℃ / min; before heating to 250℃, constant temperature roasting is carried out at 50℃ for 60-120min, and constant temperature roasting is carried out at 250℃ for 60-120min. 250-550℃, heating rate is 1-3℃ / min, before heating to 550℃, constant temperature roasting at 100℃ for 60-120min, and constant temperature roasting at 550℃ for 60-120min. 550℃ - final temperature, heating rate of 1-2℃ / min, and constant temperature calcination at the final temperature for 120-240min, with a final temperature of 600-750℃.

8. The method of recovering rhodium from a rhodium-containing solution inactivated from carbonylation synthesis according to claim 4, characterized in that, The drying temperature is 70-120℃, and the time is 6-24h; the oxidation roasting temperature is 500-650℃, and the time is 2-8h; the washing time is 0.5-2h; and the drying temperature is 110-130℃, and the time is 2-10h.

9. The method of recovering rhodium from a rhodium-containing solution inactivated from carbonylation synthesis according to claim 4, characterized in that, The stirring and mixing time is 2-12 hours. After oxidation and calcination, the product is washed with deionized water, and the mass ratio of the oxidation and calcination product to the deionized water is 1:20-1:200.

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