Method for efficiently and selectively extracting vanadium and molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst by using eutectic solvent

Abstract

The invention discloses a method for efficiently and selectively extracting vanadium and molybdenum and enriching nickel from a heavy oil hydrogenation waste catalyst by using a deep eutectic solvent, which comprises the following steps: pyrolyzing and roasting the heavy oil hydrogenation waste catalyst, and grinding to obtain a leaching raw material; the method comprises the following steps: mixing hydrogen bond acceptor choline chloride and hydrogen bond donor oxalic acid, heating and stirring until a uniform and transparent solution is formed, and cooling to obtain a primary eutectic solvent; carrying out heating treatment on the primary eutectic solvent to obtain a stable eutectic solvent; adding deionized water into the stable eutectic solvent to obtain a leaching agent; and mixing the leaching raw material with a leaching agent for leaching, and separating a solid phase from a liquid phase after the reaction is finished, so as to obtain a high-vanadium and high-molybdenum leaching solution and nickel-rich leaching residues. According to the method, choline chloride and oxalic acid are adopted as main components of the deep-eutectic solvent, the deep-eutectic solvent is environmentally friendly, low in toxicity and good in biocompatibility, the leaching rate of vanadium and molybdenum can reach 95% or above, and efficient extraction and resource utilization of valuable metal in the waste heavy oil hydrogenation catalyst are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of waste catalyst recovery and hazardous solid waste resource utilization in the petrochemical industry, and in particular to a method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalysts by using a low eutectic solvent. Background Art

[0002] With the gradual depletion of global crude oil reserves, the intensification of the trend of heavy oil resources, and the continued growth of people's demand for light, high-quality energy, the importance of heavy oil processing has become increasingly prominent. Hydroprocessing technology has been regarded as a highly promising solution in the field of heavy oil processing because it can efficiently convert heavy, low-quality crude oil into cleaner and higher-value products. However, due to the high proportion of carbon and heavy metals (such as vanadium and nickel) in heavy oil, heavy oil hydroprocessing catalysts are easily deactivated and their service life is usually only 0.5 to 1 year. Compared with catalysts used in other hydroprocessing processes, spent heavy oil hydroprocessing catalysts show more severe coke deposition, V and Ni poisoning, and thermal degradation, making these catalysts almost impossible to regenerate. Therefore, taking advantage of the high concentration of valuable metals in these catalysts, the development of effective metal recovery technologies is crucial to mitigate environmental risks and solve the problem of valuable metal shortages.

[0003] Waste heavy oil hydrogenation catalyst is rich in valuable metals such as vanadium (V), molybdenum (Mo) and nickel (Ni), and is a highly potential secondary resource. In the prior art, leaching is the main way to recover these metals from waste catalysts. Although traditional chemical leaching agents have the advantages of high recovery rate, simple operation and low energy consumption, commonly used inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid) or alkaline reagents (such as sodium hydroxide, ammonia water) are extremely corrosive and will produce a large amount of difficult-to-treat waste liquid after use, posing a serious threat to the environment. Therefore, it is of great significance to develop an environmentally friendly, low-cost and efficient metal recovery technology, especially a green solvent suitable for operation under mild conditions.

[0004] As an emerging green solvent, Deep Eutectic Solvents (DES) have become a research hotspot in the field of metal recovery in recent years due to their low toxicity, biodegradability and non-volatility. DES can be prepared at room temperature and pressure, and its excellent solubility and chemical stability make it an environmentally friendly alternative for the recovery of metals from waste catalysts. However, the existing DES system still has certain limitations in the selective separation and recovery of metals from heavy oil hydrogenation waste catalysts, and it is still difficult to achieve efficient selective extraction of vanadium and molybdenum and efficient separation from nickel. Therefore, developing an innovative method based on the DES system to achieve efficient and environmentally friendly metal extraction and separation is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalysts using choline chloride (ChCl) and oxalic acid (OA) as main components of a low eutectic solvent. The method achieves efficient and selective extraction of vanadium and molybdenum and efficient separation from nickel through a green and mild process.

[0006] The above invention object is achieved through the following technical solutions:

[0007] A method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent comprises the following steps:

[0008] Pretreatment of heavy oil hydrogenation waste catalyst, grinding the heavy oil hydrogenation waste catalyst after pyrolysis and roasting to obtain leaching raw material;

[0009] Preparation of a preliminary low eutectic solvent: mixing a hydrogen bond acceptor choline chloride and a hydrogen bond donor oxalic acid, heating and stirring until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent;

[0010] Preparation of a stable low eutectic solvent, heating the preliminary low eutectic solvent to obtain the stable low eutectic solvent;

[0011] Preparation of a leaching agent, adding deionized water to the stable low eutectic solvent to obtain the leaching agent;

[0012] Leaching reaction, the leaching raw material is mixed with the leaching agent for leaching, and after the reaction is completed, the solid phase and the liquid phase are separated to obtain a high-vanadium-molybdenum leaching solution and a nickel-rich leaching residue.

[0013] Furthermore, the pyrolysis includes: heating the heavy oil hydrogenation waste catalyst to 540°C-560°C in a nitrogen atmosphere, keeping it warm for 0.5h-1h, then stopping the heating, and blowing away the residual gas with nitrogen; the calcination includes: heating the heavy oil hydrogenation waste catalyst to 540°C-560°C in an air atmosphere, keeping it warm for 1.5h-2.5h.

[0014] Furthermore, the preparation of the preliminary low eutectic solvent comprises: mixing the hydrogen bond acceptor choline chloride and the hydrogen bond donor oxalic acid in a molar ratio of (3-1): (1-3), stirring at 70°C-80°C at a speed of 200 rpm-400 rpm until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent.

[0015] Furthermore, the preparation of the preliminary low eutectic solvent includes: mixing the hydrogen bond acceptor choline chloride and the hydrogen bond donor oxalic acid in a molar ratio of 1:2, stirring at 80° C. and 400 rpm until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent.

[0016] Furthermore, the preparation of the stable low eutectic solvent comprises: keeping the preliminary low eutectic solvent at 50° C.-70° C. for 24 h-48 h to obtain the stable low eutectic solvent.

[0017] Furthermore, the preparation of the leaching agent includes: adding 10%-40% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent.

[0018] Furthermore, the preparation of the leaching agent includes: adding 30% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent.

[0019] Furthermore, the leaching reaction includes: a liquid-to-solid ratio of the leaching agent to the leaching raw material of 15-25 mL / g, a leaching temperature of 60° C.-90° C., and a leaching time of 1 h-5 h.

[0020] Furthermore, the leaching reaction includes: a liquid-to-solid ratio of the leaching agent to the leaching raw material of 20 mL / g, a leaching temperature of 80° C., and a leaching time of 3 hours.

[0021] Furthermore, when the following conditions are met, the leaching rate of vanadium in the liquid phase reaches more than 97%, the leaching rate of molybdenum in the liquid phase reaches more than 95%, and the leaching rate of nickel in the liquid phase is less than 2%; the conditions include: the molar ratio of the hydrogen bond acceptor choline chloride and the hydrogen bond donor oxalic acid is 1:2, 30% by volume of deionized water is added to the stable low eutectic solvent to obtain the leaching agent, and the leaching reaction conditions are that the liquid-solid ratio of the leaching agent to the leaching raw material is 20 mL / g, the leaching temperature is 80°C, and the leaching time is 3h.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] (1) The present invention uses choline chloride and oxalic acid as the main components of the deep eutectic solvent (DES), which overcomes the shortcomings of traditional highly corrosive leaching agents, does not produce high-salt wastewater, and has green environmental protection, low toxicity and good biocompatibility. In addition, DES has a wide range of raw materials, low cost, simple synthesis steps, and great industrialization potential.

[0024] (2) Adding an appropriate amount of deionized water to the low eutectic solvent not only effectively reduces the viscosity of the solvent, but also further reduces the processing cost, while significantly improving the leaching efficiency and separation efficiency.

[0025] (3) The present invention achieves a vanadium leaching efficiency of up to 97.8%, a molybdenum leaching efficiency of 95.1%, and a nickel leaching efficiency of only 1.8%, successfully achieving efficient leaching of vanadium and molybdenum and one-step efficient separation from nickel.

[0026] (4) The present invention realizes the efficient extraction and resource utilization of valuable metals in waste heavy oil hydrogenation catalysts, provides a new green and efficient path for waste catalyst treatment and metal resource recycling, and shows good prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a Fourier transform infrared spectrum of choline chloride, oxalic acid and the prepared DES in Example 1 of the present invention;

[0028] Figure 2 is a diagram showing the leaching effect of the DES leaching agent on selective leaching of the spent catalyst in Example 1 of the present invention;

[0029] Figure 3 These are scanning electron microscope photographs of the waste catalyst powder (a) and the leached residue (b) in Example 1 of the present invention; wherein, (a-1) (a-2) are EDS energy spectrum analyses of the waste catalyst powder (a), and (b-1) (b-2) are EDS energy spectrum analyses of the leached residue (b). DETAILED DESCRIPTION

[0030] In order to better understand the above technical solution, the technical solution of the present invention is described in detail below through specific embodiments.

[0031] The embodiment of the present invention provides a method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent, comprising the following steps:

[0032] Pretreatment of heavy oil hydrogenation waste catalyst, grinding the heavy oil hydrogenation waste catalyst after pyrolysis and roasting to obtain leaching raw materials;

[0033] Preparation of a preliminary low eutectic solvent: mixing a hydrogen bond acceptor choline chloride and a hydrogen bond donor oxalic acid, heating and stirring until a uniform and transparent solution is formed, and cooling to obtain a preliminary low eutectic solvent;

[0034] Preparation of a stable deep eutectic solvent, heating the preliminary deep eutectic solvent to obtain a stable deep eutectic solvent;

[0035] Preparation of a leaching agent: adding deionized water to a stable deep eutectic solvent to obtain a leaching agent;

[0036] In the leaching reaction, the leaching raw material is mixed with the leaching agent for leaching, and after the reaction is completed, the solid phase and the liquid phase are separated to obtain a high-vanadium-molybdenum leaching solution and a nickel-rich leaching residue.

[0037] The method provided by the embodiment of the present invention for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a low eutectic solvent uses choline chloride (ChCl) and oxalic acid (OA) as the main components of the low eutectic solvent, and has good biocompatibility and low cost. By introducing an appropriate amount of deionized water, not only the viscosity of the solvent is effectively reduced, but also the processing cost is further reduced, while the leaching efficiency and separation efficiency are significantly improved. The embodiment of the present invention achieves efficient and selective extraction of vanadium and molybdenum through a green and gentle process, and achieves efficient separation from nickel. This method is environmentally friendly and efficient, effectively reduces environmental pollution, helps to alleviate the shortage of strategic rare metal resources, and has good prospects for industrial application.

[0038] It can be understood that after the leaching reaction is completed, the solid phase and the liquid phase are separated to obtain a high-concentration vanadium- and molybdenum-containing leaching solution and a nickel-rich leaching residue, thereby achieving efficient and selective extraction of vanadium, molybdenum and nickel enrichment.

[0039] Optionally, vacuum filtration is performed immediately after the leaching reaction to separate the solid phase and the liquid phase. The concentrations of metal vanadium, molybdenum and nickel in the leaching solution are determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the metal leaching rate is calculated. The metal leaching rate E (%) is calculated by formula (1):

[0040] E(%)=[(C Me ×V / (wt%×m)](1)

[0041] Among them, C Me (g / L) is the concentration of the metal element (Me is V, Mo or Ni);

[0042] V(L) is the volume of the leachate;

[0043] wt% is the concentration of metal Me in the spent catalyst;

[0044] m (g) is the weight of the spent catalyst.

[0045] In some embodiments, pyrolysis includes: heating the heavy oil hydrogenation waste catalyst to 540°C-560°C in a nitrogen atmosphere, keeping it warm for 0.5h-1h, then stopping the heating, and blowing away the residual gas with nitrogen; calcination includes: heating the heavy oil hydrogenation waste catalyst to 540°C-560°C in an air atmosphere, keeping it warm for 1.5h-2.5h.

[0046] Specifically, the oil-containing spent catalyst produced by the heavy oil hydroprocessing unit was pretreated in a tubular furnace by pyrolysis-calcination in two steps to remove organic compounds, coke and sulfur, and then ground to a particle size of less than 150 μm using a sample preparation machine for subsequent leaching.

[0047] In some embodiments, the preparation of a preliminary low eutectic solvent comprises: mixing a hydrogen bond acceptor choline chloride and a hydrogen bond donor oxalic acid in a molar ratio of (3-1): (1-3), stirring at 70°C-80°C at a speed of 200 rpm-400 rpm until a uniform transparent solution is formed, and cooling to obtain a preliminary low eutectic solvent. Preferably, the preparation of a preliminary low eutectic solvent comprises: mixing a hydrogen bond acceptor choline chloride and a hydrogen bond donor oxalic acid in a molar ratio of 1:2, stirring at 80°C at a speed of 400 rpm until a uniform transparent solution is formed, and cooling to obtain a preliminary low eutectic solvent.

[0048] Specifically, choline chloride and oxalic acid are mixed in a molar ratio of (3-1): (1-3), and optionally, the oxalic acid is anhydrous oxalic acid or oxalic acid dihydrate, and a low eutectic solvent based on choline chloride and oxalic acid is successfully prepared for selective extraction of vanadium, molybdenum and enrichment of nickel in heavy oil hydrogenation waste catalyst. The heating temperature should not be too high to avoid decomposition of oxalic acid, and the stirring speed is controlled at 200 rpm-400 rpm to ensure uniform heating and reaction of the mixture.

[0049] In some embodiments, the preparation of a stable low eutectic solvent comprises: keeping a preliminary low eutectic solvent at 50°C-70°C for 24h-48h to obtain a stable low eutectic solvent. Preferably, the preparation of a stable low eutectic solvent comprises: keeping a preliminary low eutectic solvent at 50°C for 24h to obtain a stable low eutectic solvent.

[0050] Specifically, through heating and insulation treatment, the molecular structure of the low eutectic solvent is more stable, which significantly improves the leaching efficiency and the reliability of the results; at the same time, the stable low eutectic solvent has good solubility and selectivity, and can efficiently and selectively extract vanadium and molybdenum, and achieve precise separation from nickel.

[0051] In some embodiments, the preparation of the leaching agent comprises: adding 10%-40% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent. More preferably, the preparation of the leaching agent comprises: adding 20%-30% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent. Most preferably, the preparation of the leaching agent comprises: adding 30% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent.

[0052] Specifically, adding an appropriate amount of deionized water to the stable low eutectic solvent not only effectively reduces the viscosity of the solvent, but also further reduces the processing cost, while significantly improving the leaching efficiency and separation efficiency. Adding 10%-40% of deionized water by volume to the stable low eutectic solvent refers to adding 10%-40% of deionized water by volume to the stable low eutectic solvent.

[0053] In some embodiments, we conduct a single factor experiment on the parameter conditions of the leaching reaction and obtain the preferred conditions for the leaching reaction: preferably, the liquid-solid ratio of the leaching agent to the leaching raw material is 15-25 mL / g, the preferred leaching temperature is 60°C-90°C, and the preferred leaching time is 1h-5h. More preferably, the liquid-solid ratio of the leaching agent to the leaching raw material is 20-25 mL / g, the leaching temperature is 70°C-90°C, and the leaching time is 3h-5h. Most preferably, the liquid-solid ratio of the leaching agent to the leaching raw material is 20 mL / g, the leaching temperature is 80°C, and the leaching time is 3h.

[0054] In summary, when the following conditions (1) to (3) are met: the leaching rate of vanadium in the liquid phase reaches more than 97%, the leaching rate of molybdenum in the liquid phase reaches more than 95%, and the leaching rate of nickel in the liquid phase is less than 2%. Among them, condition (1) is that the molar ratio of hydrogen bond acceptor choline chloride and hydrogen bond donor oxalic acid is 1:2, condition (2) is that 30% by volume of deionized water is added to the stable low eutectic solvent to obtain a leaching agent, and condition (3) is that the leaching reaction conditions are that the liquid-solid ratio (mL / g) of the leaching agent to the leaching raw material is 20, the leaching temperature is 80°C, and the leaching time is 3h.

[0055] Example 1 A method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent

[0056] This example provides a method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from a heavy oil hydrogenation waste catalyst using a deep eutectic solvent, comprising the following steps:

[0057] (1) Pretreatment: A two-step pyrolysis-calcination method is used in a tubular furnace. The pyrolysis is to heat the temperature to 550°C at a heating rate of 10°C / min under a nitrogen environment. The insulation time varies according to the oil content of different batches of waste catalysts. The average insulation time is about 30min-1h, based on the fact that smoke is no longer generated in the tubular furnace. After that, stop heating, keep nitrogen purging, and close the pyrolysis channel after all the residual gas in the tube is purged into the condensing device. When the furnace temperature is lower than 337°C, open the calcination channel, and start heating to 550°C at a heating rate of 10°C / min under flowing air, with a residence time of 2h. Then grind to a particle size of less than 150μm to obtain a leaching raw material suitable for metal recovery;

[0058] (2) Synthesis of preliminary DES solvent: 0.15 mol of choline chloride ChCl and 0.3 mol of oxalic acid OA were mixed (the molar ratio of ChCl to OA was 1:2), and the mixture was stirred at 80°C and 400 rpm until a uniform transparent solution was formed. The synthesized transparent solution was cooled to room temperature to preliminarily prepare the DES solvent;

[0059] (3) Stabilization of DES solvent: To stabilize the DES solvent, the solution was transferred to a sealed glass container and kept in an oven at 50 °C for 24 h to obtain a stable DES solution;

[0060] (4) Preparation of the final DES leaching agent: 30% by volume of deionized water was added to the obtained DES solution to prepare the final leaching agent;

[0061] (5) adding 1 g of the waste catalyst powder pretreated and ground in step (1) to 20 ml of the final leaching agent, with a liquid-to-solid ratio (ml / g) of 20, and reacting in a water bath at 80° C. for 5 h;

[0062] (6) Vacuum filtration was performed immediately after leaching to separate the solid phase and the liquid phase. The concentrations of metal vanadium, molybdenum and nickel in the leaching solution were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the metal leaching rate was calculated.

[0063] The method of using a low eutectic solvent to efficiently and selectively extract vanadium, molybdenum and enrich nickel from heavy oil hydrogenation waste catalyst in Example 1 was tested as follows: verification of DES synthesis, detection of vanadium, molybdenum and nickel leaching rates, and morphology and composition analysis of the product, thereby obtaining the following experimental results:

[0064] (1) The DES prepared in this example was detected by Fourier transform infrared spectrometer, and the following was obtained after treatment: Figure 1 As shown in the picture. As shown in the figure, three curves of ChCl, DES and OA were obtained. It can be found that the stretching vibration of -OH of DES has obvious displacement and the peak has become significantly broadened. This indicates that a wide hydrogen bond network has been formed between the hydrogen bond acceptor ChCl and the hydrogen bond donor OA, confirming the synthesis of DES.

[0065] (2) The metal content of the leaching solution in Example 1 of the present invention was tested by inductively coupled plasma emission spectrometry to measure the leaching concentrations of vanadium, molybdenum and nickel, and their leaching rates were calculated. The leaching effects of the spent catalyst powder at different times are shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the DES leaching solution exhibits strong leaching ability and high efficiency. The leaching rates of vanadium and molybdenum reach 88.2% and 86.7% respectively in just 1 hour. As the leaching time increases, the leaching rates of vanadium and molybdenum gradually increase. When the leaching time is 3 hours, the leaching rates of vanadium and molybdenum both exceed 95%, reaching 97.8% and 95.1% respectively, while the leaching rate of nickel is only 1.8% at this time. This shows that the DES solution in Example 1 of the present invention can efficiently and selectively extract vanadium and molybdenum from heavy oil hydrogenation waste catalyst and separate them from nickel, and its extraction efficiency is high and can be completed within 3 hours.

[0066] (3) Using a scanning electron microscope, the morphology and composition analysis of the spent catalyst powder after pretreatment in step (1) of Example 1 and the leached residue obtained after leaching were performed respectively. Figure 3 (a) and 3(b) are scanning electron microscope photos of spent catalyst powder and leached residue. Through the morphological analysis of the raw material and leached residue, it was found that the surface of the raw material was relatively dense, while the surface structure of the leached residue changed significantly and showed porous characteristics, indicating that the dissolution and selective extraction of the material during the leaching process led to the destruction and reorganization of the structure. From the EDS energy spectrum analysis, it can be seen that the content of vanadium and molybdenum in the leached residue is greatly reduced, while the content of nickel is significantly enriched, indicating that this method achieves efficient selective leaching of vanadium and molybdenum and effective enrichment of nickel. This result is consistent with the ICP analysis data, further verifying the superiority and reliability of this method.

[0067] Example 2 Effect of the molar ratio of ChCl and OA in the deep eutectic solvent on the extraction of vanadium, molybdenum and enrichment of nickel

[0068] This example uses the waste catalyst powder that has been pretreated and ground in step (1) of Example 1 to conduct a leaching experiment. The specific steps are as follows:

[0069] (1) DES synthesis and leaching: Choline chloride (ChCl) and oxalate (OA) were mixed in a molar ratio of 1:2, and control experimental groups with molar ratios of ChCl to OA of 3:1, 2:1, 1:1, and 1:3 were set up; the mixture was stirred at 80°C and 400 rpm until a uniform transparent solution was formed. The synthesized transparent solution was cooled to room temperature to preliminarily prepare a DES solvent; the solution was transferred to a sealed glass container and kept in an oven at 50°C for 24 hours to obtain a stable DES solution; 30% by volume of deionized water was added to the DES solution to prepare the final DES leaching agent.

[0070] (2) The pretreated and ground spent catalyst powder was added to the final DES leaching agent at a liquid-to-solid ratio (ml / g) of 20, and the mixture was in a water bath at 80°C for 3 h to obtain leaching solutions, and the concentrations of vanadium, molybdenum and nickel in the leaching solutions were determined.

[0071] After testing, it was found that in five groups of control experiments, when the molar ratios of ChCl and OA were 3:1, 2:1, 1:1, 1:2 and 1:3 respectively, after leaching in a water bath at 80°C for 3 hours, the leaching rates of vanadium, molybdenum and nickel were shown in Table 1 below.

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, as the molar ratio of oxalic acid increases, the acidic environment and coordination ability are significantly enhanced, and the leaching rate of metals gradually increases. However, during the leaching process, molybdenum is more difficult to leach than vanadium. Although the solutions with a molar ratio of 1:2 and 1:3 both show good leaching effects, the solution with a molar ratio of 1:3 has poor stability and high viscosity. After comprehensive consideration, the molar ratio of ChCl to OA of 1:2 was selected as the optimal condition.

[0076] Example 3 Effect of leaching liquid-solid ratio on extraction of vanadium, molybdenum and enrichment of nickel

[0077] This example uses the waste catalyst powder that has been pretreated and ground in step (1) of Example 1 to conduct a leaching experiment. The specific steps are as follows:

[0078] (1) DES synthesis and leaching: Choline chloride (ChCl) and oxalate (OA) were mixed in a molar ratio of 1:2, and the mixture was stirred at 80°C and 400 rpm until a uniform transparent solution was formed. The synthesized transparent solution was cooled to room temperature to preliminarily prepare a DES solvent; the solution was transferred to a sealed glass container and kept in an oven at 50°C for 24 hours to obtain a stable DES solution; 30% by volume of deionized water was added to the DES solution to prepare the final DES leaching agent.

[0079] (2) The pretreated spent catalyst powder was added to the final DES leaching agent at a liquid-to-solid ratio (mL / g) of 20. At the same time, control experimental groups with liquid-to-solid ratios of 5, 10, 15, 25, and 30 were set up; the leaching solutions were obtained by water bathing at 80°C for 3 h. The concentrations of vanadium, molybdenum, and nickel in the leaching solutions were determined and shown in Table 2.

[0080] Table 2

[0081]

[0082]

[0083] It can be seen from Table 2 that when the liquid-to-solid ratio is 20 and 25, the leaching rates of vanadium and molybdenum are similar, but considering the experimental cost comprehensively, the final preferred liquid-to-solid ratio is 20.

[0084] Example 4 Effect of leaching temperature and time on extraction of vanadium, molybdenum and enrichment of nickel

[0085] This example uses the waste catalyst powder that has been pretreated and ground in step (1) of Example 1 to conduct a leaching experiment. The specific steps are as follows:

[0086] (1) DES synthesis and leaching: Choline chloride (ChCl) and oxalate (OA) were mixed in a molar ratio of 1:2, and the mixture was stirred at 80°C and 400 rpm until a uniform transparent solution was formed. The synthesized transparent solution was cooled to room temperature to preliminarily prepare a DES solvent; the solution was transferred to a sealed glass container and kept in an oven at 50°C for 24 hours to obtain a stable DES solution; 30% by volume of deionized water was added to the DES solution to prepare the final DES leaching agent.

[0087] (2) The pretreated and ground spent catalyst powder was added to the final DES leaching agent with a liquid-to-solid ratio (ml / g) of 20. The leaching agent was placed in a water bath at 80°C for 3 h. Control experimental groups were set up at 50°C for 3 h, 60°C for 3 h, 70°C for 3 h, and 90°C for 3 h to obtain leachates. The concentrations of vanadium, molybdenum, and nickel in the leachates were determined and are shown in Table 3.

[0088] Table 3

[0089] Leaching temperature (℃) V(％) Mo(%) Ni(%) 50 64.4 61.8 4.6 60 90.9 87.5 1.7 70 95.2 93.4 1.8 80 97.8 95.1 1.8 90 97.9 95.3 1.9

[0090] Under the leaching condition of 80°C for 3h, the leaching rates of vanadium and molybdenum were higher than 95%. Considering the energy cost, 80°C for 3h was selected as the preferred leaching temperature.

[0091] Example 5 Effect of the amount of water added to the deep eutectic solvent on the extraction of vanadium, molybdenum and nickel enrichment

[0092] This example uses the waste catalyst powder that has been pretreated and ground in step (1) of Example 1 to conduct a leaching experiment with different water addition amounts in a deep eutectic solvent. The specific steps are as follows:

[0093] (1) Synthesis and leaching of water-free DES: Choline chloride (ChCl) and oxalic acid (OA) were mixed in a molar ratio of 1:2, and the mixture was stirred at 80°C and 400 rpm until a uniform transparent solution was formed. The synthesized transparent solution was cooled to room temperature; the solution was transferred to a sealed glass container and kept in an oven at 50°C for 24 hours to form a low eutectic solvent.

[0094] (2) 1 g of pretreated and ground waste catalyst powder was added to 20 ml of non-aqueous DES solution, 10% by volume of deionized water was added to the DES solution, 20% by volume of deionized water was added to the DES solution, 30% by volume of deionized water was added to the DES solution, and 40% by volume of deionized water was added to the DES solution, with a liquid-to-solid ratio of 20. The mixture was placed in a water bath at 80° C. for 3 h to obtain leaching solutions. ICP tests were performed on each leaching solution to determine the leaching rate of vanadium, molybdenum and nickel. The results are shown in Table 4.

[0095] Table 4

[0096] Water volume ratio V(％) Mo(%) Ni(%) 0 82.7 81.8 4.2 10％ 90.6 88.2 1.9 20％ 96.9 95.2 2.0 30％ 97.8 95.1 1.8 40％ 94.1 92.8 1.6

[0097] As can be seen from Table 4, the leaching effect of adding 30% volume ratio of deionized water to the DES solution is the best. This may be due to the high viscosity of the DES solution without water, resulting in incomplete reaction during the leaching process. At the same time, the high viscosity also affects the separation effect, resulting in an increase in the leaching rate of nickel. It can be seen that adding an appropriate amount of water to DES can not only reduce the viscosity of the solution, thereby promoting the leaching process, but also optimize the solid-liquid separation effect and significantly improve the leaching efficiency of vanadium and molybdenum. In addition, adding water can also effectively reduce costs, further highlighting the significant advantages of the leaching agent of the present invention.

[0098] Comprehensive test results of Examples 1-5 show that the method provided by the present invention for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalysts using a low eutectic solvent has the advantages of simple operation, low cost and high efficiency. Compared with the traditional waste catalyst metal recovery method, the present invention not only solves the problem of insufficient and incomplete recovery, but also realizes efficient selective extraction of vanadium and molybdenum and effective enrichment of nickel. In addition, compared with other types of low eutectic solvents, the aqueous DES prepared by choline chloride (ChCl) and oxalic acid (OA) in the present invention has better fluidity and stability, low viscosity, and significantly improved leaching effect, and the leaching rate of vanadium and molybdenum can reach more than 95%. At the same time, the DES raw material of the present invention is low in price and small in dosage, which further reduces the leaching cost and shows good economic performance and industrial prospects. The recovered product has excellent morphology, uniform particle distribution and large specific surface area, which provides reliable guarantee for subsequent reuse. The method of the present invention has a wide range of application value in the efficient recovery and utilization of waste catalyst metal resources.

[0099] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application. The above are only preferred implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent, characterized in that: The steps include: Pretreatment of heavy oil hydrogenation waste catalyst, grinding the heavy oil hydrogenation waste catalyst after pyrolysis and roasting to obtain leaching raw material; Preparation of a preliminary low eutectic solvent: mixing a hydrogen bond acceptor choline chloride and a hydrogen bond donor oxalic acid, heating and stirring until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent; Preparation of a stable low eutectic solvent, heating the preliminary low eutectic solvent to obtain the stable low eutectic solvent; Preparation of a leaching agent, adding deionized water to the stable low eutectic solvent to obtain the leaching agent; Leaching reaction, the leaching raw material is mixed with the leaching agent for leaching, and after the reaction is completed, the solid phase and the liquid phase are separated to obtain a high-vanadium-molybdenum leaching solution and a nickel-rich leaching residue.

2. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: The pyrolysis comprises: heating the heavy oil hydrogenation waste catalyst to 540° C.-560° C. in a nitrogen atmosphere, keeping the temperature for 0.5 h-1 h, then stopping the heating, and purging the residual gas with nitrogen; The calcination comprises: heating the heavy oil hydrogenation waste catalyst to 540° C.-560° C. in an air atmosphere, and keeping the temperature for 1.5 h-2.5 h.

3. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: The preparation of the preliminary low eutectic solvent comprises: mixing the hydrogen bond acceptor choline chloride and the hydrogen bond donor oxalic acid in a molar ratio of (3-1):(1-3), stirring at 70°C-80°C at a speed of 200 rpm-400 rpm until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent.

4. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 3, characterized in that: The preparation of the preliminary low eutectic solvent comprises: mixing the hydrogen bond acceptor choline chloride and the hydrogen bond donor oxalic acid in a molar ratio of 1:2, stirring at 80° C. and 400 rpm until a uniform and transparent solution is formed, and cooling to obtain the preliminary low eutectic solvent.

5. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: The preparation of the stable low eutectic solvent comprises: keeping the preliminary low eutectic solvent at 50° C.-70° C. for 24 h-48 h to obtain the stable low eutectic solvent.

6. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: The preparation of the leaching agent comprises: adding deionized water in a volume ratio of 10% to 40% to the stable low eutectic solvent to obtain the leaching agent.

7. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 6, characterized in that: The preparation of the leaching agent comprises: adding 30% by volume of deionized water to the stable low eutectic solvent to obtain the leaching agent.

8. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: The leaching reaction comprises: a liquid-solid ratio of the leaching agent to the leaching raw material of 15-25 mL / g, a leaching temperature of 60° C.-90° C., and a leaching time of 1 h-5 h.

9. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 8, characterized in that: The leaching reaction includes: the liquid-to-solid ratio of the leaching agent to the leaching raw material is 20 mL / g, the leaching temperature is 80° C., and the leaching time is 3 hours.

10. The method for efficiently and selectively extracting vanadium, molybdenum and enriching nickel from heavy oil hydrogenation waste catalyst using a deep eutectic solvent according to claim 1, characterized in that: When the following conditions are met: the molar ratio of the hydrogen bond acceptor choline chloride to the hydrogen bond donor oxalic acid is 1:2, 30% by volume of deionized water is added to the stable low eutectic solvent to obtain the leaching agent, and the leaching reaction conditions are that the liquid-solid ratio of the leaching agent to the leaching raw material is 20 mL / g, the leaching temperature is 80° C., and the leaching time is 3 hours; The leaching rate of vanadium in the liquid phase reaches more than 97%, the leaching rate of molybdenum in the liquid phase reaches more than 95%, and the leaching rate of nickel in the liquid phase is less than 2%.

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