Process for the regeneration of fcc spent catalyst

Abstract

The present application relates to the technical field of catalyst regeneration, and discloses a regeneration method of FCC spent catalyst. The method comprises the following steps: (1) mixing the FCC spent catalyst with a hydrogen peroxide solution, and then performing heat treatment on the obtained mixture to obtain clinker; (2) performing acid leaching on the clinker obtained in step (1) by using an acidic solution, and then performing solid-liquid separation to obtain regenerated FCC catalyst; wherein in step (1), the liquid-solid ratio of the hydrogen peroxide solution to the FCC spent catalyst is 0.6-1.1:1 mL / g, and the concentration of the hydrogen peroxide solution is 1-10 wt%. The regeneration method has the advantages of simple treatment process, short operation time, high removal rate of harmful metals, and complete molecular sieve structure of silicon-aluminum salt in the leaching residue.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst regeneration, in particular to a regeneration method of FCC spent catalyst. BACKGROUND

[0002] Catalytic cracking (FCC) is one of the core technologies for oil refining enterprises to produce gasoline, diesel, low-carbon olefins and other high-value products from heavy oil. FCC catalyst is the largest amount of catalyst used in petroleum refining process, and the current usage of FCC catalyst in China is more than 150,000 tons / year. With the increasingly mediumization and inferiorization of raw materials, the content of harmful substances such as heavy metals and residual carbon in crude oil is high. With the continuous recycling of FCC catalyst, these harmful substances deposited on the FCC catalyst gradually increase, which significantly reduces the specific surface area and pore volume of the FCC spent catalyst with the extension of time, and eventually significantly reduces its activity and selectivity. Therefore, the cracking plant needs to discharge a large amount of spent catalyst every day and supplement an equal amount of new catalyst. About 1.2-1.5 kg of FCC catalyst is consumed per ton of raw oil processed, and the balance agent discharged accounts for about 60-70% of the total amount, becoming spent catalyst. China is expected to increase about 5% of FCC spent catalyst per year, and soon it will exceed 200,000 tons of FCC spent catalyst per year. The current price of fresh FCC catalyst is 15-20 thousand yuan / ton, and if the regeneration or regeneration research of spent catalyst or balance agent is considered, the social, environmental and economic benefits are considerable. Due to the combined effects of high temperature, carbon deposition and heavy metal deposition,

[0003] The waste catalyst contains about 1-4% of rare earth oxide, 2000-5000 ppm of V, 3000-8000 ppm of Ni, 1000-4000 ppm of Fe, Ca, Cu, etc., and belongs to solid waste. At present, except for a small amount of waste catalyst used for soil improvement or as raw material for cement and ceramic production, most of the waste catalyst is discarded by underground burial. Underground burial not only causes the loss of heavy metal resources, but also pollutes underground water and soil. With the increasing improvement of national environmental protection standards, the treatment of solid waste is becoming more and more strict, and the treatment and utilization of waste FCC catalyst has become a very important problem. The waste FCC catalyst is composed of zeolite (molecular sieve), which is a crystalline silicate with SiO2 and Al2O3 as main components, has a crystal lattice structure, and has a large specific surface area and pore volume. Although the waste FCC catalyst has lost its catalytic activity, its molecular sieve structure has not been completely destroyed and still has certain utilization value. If an effective regeneration process is used to make the regenerated catalyst return to the catalytic cracking unit and the heavy metals, especially nickel, are effectively recycled, the resource utilization of waste FCC catalyst is realized and the environment is protected. At present, there are relatively few reports on the regeneration methods of waste FCC catalyst at home and abroad. The main methods reported include acid washing, carbonylation-chlorination, sulfidation-oxidation, and magnetic spinning method. These methods are mainly aimed at removing Ni, V, Fe and other heavy metals in the catalyst to partially restore the reaction performance of the catalyst. For example, the existing sulfidation-oxidation process and chlorination process, and magnetic separation process only remove a small amount of heavy metals, so that the activity of the regenerated catalyst can be increased by only 2-3 points; and the regeneration process is complicated and the regeneration cost is high. US5151391 provides a process for regenerating waste FCC catalyst by treating it in an aqueous solution of hydrochloric acid and / or nitric acid and / or sulfuric acid. The regenerated catalyst can be used in a catalytic cracking process. However, due to the use of a large amount of inorganic acid and / or organic acid, the regeneration operation process is extremely inconvenient and has a risk of use. CN101219396B uses the synergistic effect of inorganic acid and organic acid to treat FCC waste catalyst containing heavy metals. Specifically, 1 kg of FCC waste catalyst is added to a container, 4-8 liters of inorganic acid solution with a pH value of 1-5 is added under stirring, heated to 80-120℃, then 0.05-0.2 mol of organic acid solution 3-5 liters is added, and kept at 80-120℃ for 4-8 hours. After the reaction is completed, it is cooled to room temperature, washed to neutral, and dried to obtain a regenerated catalyst. The specific surface area of the regenerated catalyst obtained by this method increases significantly, the heavy metal removal rate reaches 30%, and the micro-reaction activity can be increased by more than 10 points. However, the reaction process control of this method is relatively complex. CN201710624515.2 discloses a regeneration method for treating waste FCC catalyst with hydrogen peroxide and ammonium salt.Specifically, 1 kg of FCC spent catalyst is added into 3-5 L of deionized water, 100-300 ml of 30% hydrogen peroxide is slowly added under stirring, and then 100-300 g of ammonium salt (ammonium carbonate and / or ammonium bicarbonate) is added under stirring. The mixture is kept at 60-100°C for 0.5-2 h. After the reaction is completed, the reaction product is cooled to room temperature, filtered, and then calcined at 200-500°C for 2-6 h to obtain the regenerated catalyst. This method oxidizes the heavy metals and ions thereof deposited on the FCC spent catalyst through the oxidation of hydrogen peroxide under alkaline conditions, and realizes the reconstruction of the catalyst structure through the pore expansion of the ammonium salt, the chemical reaction of the ammonium salt cation and the metal oxide anion. In the reconstruction process, not only the heavy metals such as Ni and V are removed, but also the pore structure of the catalyst is changed, the gradient distribution of the catalyst pore structure is realized, the porosity of the catalyst is improved, and the specific surface area of the catalyst is increased, thereby improving the catalytic reaction performance of the catalyst. However, this method needs to be regenerated by calcination, and the energy consumption is high.

[0004] It can be seen that these existing methods have complex process flow, long operation time, high energy consumption, and the use of a large amount of inorganic acid and / or organic acid makes the regeneration operation process extremely inconvenient and dangerous, and the regeneration requires higher requirements and a more complex process. Therefore, it is still necessary to explore a safe and convenient regeneration process technology for FCC spent catalyst. SUMMARY

[0005] The purpose of the present application is to overcome the problems of complex regeneration operation and high danger of FCC spent catalyst in the prior art, and to provide a method for regenerating FCC spent catalyst, which has simple treatment process, short operation time, high removal rate of harmful metals, and complete structure of silicon aluminum salt molecular sieve in leaching residue.

[0006] In view of the above technical problems, the inventors of the present application have unexpectedly found that by oxidizing the difficult-to-handle phase in the spent catalyst into an oxide through hydrogen peroxide oxidation, and then leaching with an acidic solution, both harmful metals can be removed and the microtopography of the spent catalyst particles and the structure of the useful Y-type molecular sieve can be preserved, thereby completing the present application.

[0007] In order to achieve the above-mentioned purpose, the present application provides a method for regenerating FCC spent catalyst, which comprises the following steps:

[0008] (1) mixing the FCC spent catalyst with a hydrogen peroxide solution, and then heat-treating the obtained mixture to obtain a clinker;

[0009] (2) acid leaching the clinker obtained in step (1) with an acidic solution, and solid-liquid separation to obtain a regenerated FCC catalyst;

[0010] In step (1), the liquid-solid ratio of the hydrogen peroxide solution to the FCC spent catalyst is 0.6-1.1:1 mL / g, and the concentration of the hydrogen peroxide solution is 1-10% by weight.

[0011] Preferably, in step (1), the liquid-solid ratio of the hydrogen peroxide solution to the FCC spent catalyst is 0.7-1:1 mL / g, and the concentration of the hydrogen peroxide solution is 3-5% by weight.

[0012] Preferably, in step (1), the temperature of the heat treatment is 50-140℃, preferably 80-140℃, and more preferably 80-110℃.

[0013] Preferably, in step (1), the time of the heat treatment is 10-60 min, preferably 30-45 min.

[0014] Preferably, in step (1), the method of the heat treatment is microwave heating and / or electric heating.

[0015] Preferably, in step (2), the liquid-solid ratio of the acidic solution to the clinker is 3-10:1 mL / g, preferably 5-7:1 mL / g.

[0016] Preferably, in step (2), the pH of the acidic solution is 3-5.

[0017] Preferably, in step (2), the pH of the solution is maintained at 3-5 during the acid leaching process.

[0018] Preferably, in step (2), the acidic solution is an acid solution or a mixed solution of acid and salt.

[0019] Preferably, the acid in the acid solution is one or more of hydrochloric acid, oxalic acid, sulfurous acid, sulfuric acid, acetic acid, phosphoric acid, tartaric acid, and citric acid.

[0020] Preferably, in step (2), the temperature of the acid leaching is 50-100℃, and the time of the acid leaching is 10-120 min.

[0021] Preferably, in step (2), the regenerated FCC catalyst comprises a silicon-aluminum salt molecular sieve with a crystal lattice structure.

[0022] By the above technical solution, the regeneration method has the following advantages:

[0023] (1) The present application provides an effective and mild method for regenerating spent FCC catalyst, which has the advantages of simple treatment process, easy operation, high removal rate of harmful metals, and good regeneration effect of spent catalyst.

[0024] (2) The Y-type molecular sieve obtained by the method has complete structure, and the micro-morphology of the catalyst particles is basically retained.

[0025] (3) The method can efficiently remove harmful metals from waste FCC catalysts, effectively regenerate the activity of the waste catalysts, and directly reuse the waste catalysts. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a flowchart of the regeneration method of the FCC waste catalyst of the present application;

[0027] Figure 2 is a SEM image of the regenerated FCC catalyst in Example 1 of the present application;

[0028] Figure 3 is a SEM image of the regenerated FCC catalyst in Example 1 of the present application;

[0029] Figure 4 is an XRD image of the regenerated FCC catalyst and the FCC waste catalyst in Example 1 of the present application;

[0030] Figure 5 is a SEM image of the regenerated FCC catalyst in Example 2 of the present application;

[0031] Figure 6 is an XRD image of the regenerated FCC catalyst and the FCC waste catalyst in Example 3 of the present application. DETAILED DESCRIPTION

[0032] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact numerical values of the endpoints of the ranges and any values are approximations that allow for a little variation either ways without resulting in a change in the basic function of the compositions or methods, or methods described herein. The exact numerical values of the endpoints of the ranges and any values are not to be construed in a manner against the applicant, but rather the preferred scope of equivalents based on reasonable expectation.

[0033] The present application provides a regeneration method of FCC waste catalyst, which comprises the following steps:

[0034] (1) mixing the FCC waste catalyst with a hydrogen peroxide solution, and then performing heat treatment on the obtained mixture to obtain a clinker;

[0035] (2) performing acid leaching on the clinker obtained in step (1) by using an acidic solution, and then performing solid-liquid separation to obtain a regenerated FCC catalyst;

[0036] In step (1), the liquid-solid ratio of the hydrogen peroxide solution to the FCC waste catalyst is 0.6-1.1: 1 mL / g, and the concentration of the hydrogen peroxide solution is 1-10 wt%.

[0037] In the present application, step (1) is to oxidize the FCC spent catalyst with a mild hydrogen peroxide solution to obtain a paste-like clinker. By properly controlling the amount and concentration of the hydrogen peroxide solution in step (1), the treatment effect can be better achieved.

[0038] Preferably, in step (1), the liquid-solid ratio of the hydrogen peroxide solution to the FCC spent catalyst is 0.7-1:1 mL / g, and the concentration of the hydrogen peroxide solution is 3-5 wt%.

[0039] By treating the FCC spent catalyst at the above amount and concentration, the metal removal rate and the micro-reaction activity of the regenerated FCC catalyst obtained can be further improved.

[0040] In order to ensure the treatment effect of the hydrogen peroxide solution, preferably, the temperature of the heat treatment is 50-140°C, preferably 80-140°C, and more preferably 80-110°C. More preferably, the time of the heat treatment is 10-60 min, preferably 30-45 min.

[0041] The specific heating method used in the heat treatment is not particularly limited, and conventional heating methods can be used, such as microwave heating, electric heating, etc., or microwave-assisted electric heating, etc.

[0042] In the present application, step (2) is to treat the clinker obtained in step (1) with an acidic solution, so that the regenerated FCC catalyst can be separated and obtained. Moreover, after the treatment by the method of the present application, the acid leaching process can be treated at a lower acid concentration, and the metal leaching rate can be improved.

[0043] According to the present application, in step (2), the acidic solution can be an acid solution or a mixed solution of acid and salt. Preferably, the acid in the acid solution is one or more of hydrochloric acid, oxalic acid, sulfurous acid, sulfuric acid, acetic acid, phosphoric acid, tartaric acid, and citric acid, and more preferably one or more of hydrochloric acid, oxalic acid, and sulfurous acid.

[0044] In order to improve the effect of acid leaching, preferably, the pH of the acidic solution is 3-5, and can be 3, 3.5, 4, 4.5, or 5, etc. In order to make the acidic solution reach the above-mentioned required pH, the method of controlling the acid concentration can be used, or the method of mixing ammonia water, aluminum hydroxide, aluminum oxide, etc. alkaline substances in the solution can be used. Preferably, dilute sulfuric acid solution, oxalic acid solution mixed with ammonia water, sulfurous acid solution mixed with ammonia water and / or aluminum hydroxide and / or aluminum oxide, etc. can be used.

[0045] According to the present application, in step (2), the liquid-solid ratio of the acid solution to the clinker is 3-10:1 mL / g, preferably 5-7:1 mL / g.

[0046] According to the present application, in step (2), the temperature of the acid leaching is 50-100℃, preferably 50-90℃. And the time of the acid leaching can be 10-120 min, preferably 30-90 min.

[0047] More preferably, the pH of the solution is maintained at 3-5 during the acid leaching. Specifically, the pH of the solution can be maintained by adding acid and / or base during the acid leaching, preferably by adding acid in the acid solution.

[0048] After the completion of the acid leaching process, the regenerated FCC catalyst and the leaching solution containing harmful metal elements (V, Fe, Ni, etc.) can be obtained by solid-liquid separation. Specifically, the solid-liquid separation can be achieved by using methods commonly used for separating FCC catalysts, such as filtration, centrifugation, etc.

[0049] By using the method of the present application, the FCC catalyst (silicate-aluminate molecular sieve) with crystal lattice structure can be obtained. The regeneration method of the present application is particularly suitable for the regeneration of Y-type molecular sieve, and the regeneration process can achieve the removal of harmful metals such as iron, vanadium, nickel, etc., while preserving the microstructure of the waste catalyst particles and the structure of the Y-type molecular sieve, achieving the effect of regenerating the FCC catalyst.

[0050] The present application will be described in detail by way of examples below. In this specification, "%" means "wt%" unless otherwise specified. In the following examples, the FCC waste catalyst is provided by Yanshan Petrochemical.

[0051] Example 1

[0052] As shown in the following steps, the FCC waste catalyst is regenerated: Figure 1

[0053] Step 1: First, the FCC waste catalyst is mixed with 4% hydrogen peroxide solution at a liquid-solid ratio of 1:1 mL / g, and then calcined in a microwave field at a temperature of 110℃ for 30 min to obtain clinker;

[0054] Step 2: The clinker obtained in step 1 is mixed with oxalic acid + ammonia water mixture (a mixture obtained by adjusting the pH of 0.01M oxalic acid to 3 with ammonia water) at a liquid-solid ratio of 6:1 mL / g, and then acid leached at a leaching temperature of 50℃ for 30 min, and then filtered to obtain a leaching solution containing iron, vanadium and nickel, and a leaching residue of silicate-aluminate molecular sieve with crystal lattice structure, thereby achieving the removal of harmful metals such as iron, vanadium and nickel, while preserving the microstructure of the waste catalyst particles and the structure of the Y-type molecular sieve, achieving the effect of regenerating the FCC catalyst.​

[0055] The leaching rates of the harmful metals V, Fe, and Ni are 72%, 40%, and 12%, respectively.

[0056] The SEM and XRD images of the activated FCC catalyst obtained in this example are shown in Figure 2 , 3 and Figure 4 . It can be seen that the appearance and Y-type molecular sieve structure of the catalyst particles after regeneration are maintained, and the recovery process does not substantially affect the crystalline morphology of the FCC catalyst.

[0057] Example 2

[0058] As shown in Figure 1 , the specific steps of the hydrogen peroxide pretreatment-acid leaching regeneration method for the FCC waste catalyst are as follows:

[0059] Step 1: First, mix the FCC waste catalyst with hydrogen peroxide with a concentration of 4% at a liquid-solid ratio of 0.7:1 mL / g, and then calcine in a microwave field at a calcination temperature of 100°C for 40 min to obtain clinker;

[0060] Step 2: Mix the clinker obtained in step 1 with a dilute sulfuric acid solution (pH value of 4) at a liquid-solid ratio of 5:1 mL / g, and then acid leach at a leaching temperature of 70°C for 60 min, and then filter to obtain a leaching solution containing iron, vanadium, and nickel, and a leaching residue of a silicon-aluminum salt molecular sieve with a crystal structure, thereby achieving the removal of harmful metals of iron, vanadium, and nickel, while preserving the microstructure of the waste catalyst particles and the structure of the Y-type molecular sieve, achieving the effect of regenerating the FCC catalyst.

[0061] The leaching rates of the harmful metals V, Fe, and Ni are 68%, 36%, and 17%, respectively.

[0062] The SEM and XRD images of the activated FCC catalyst obtained in this example are shown in Figure 5 and Figure 6 . It can be seen that the appearance and Y-type molecular sieve structure of the catalyst particles after regeneration are maintained, and the recovery process does not substantially affect the crystalline morphology of the FCC catalyst.

[0063] Example 3

[0064] As shown in Figure 1 , the specific steps of the hydrogen peroxide pretreatment-acid leaching regeneration method for the FCC waste catalyst are as follows:

[0065] Step 1: First, mix the FCC waste catalyst with hydrogen peroxide with a concentration of 3% at a liquid-solid ratio of 0.7:1 mL / g, and then calcine in a microwave field at a calcination temperature of 80°C for 45 min to obtain clinker;

[0066] Step 2, 0.01M sulfurous acid is stirred with aluminum hydroxide until the aluminum source is dissolved, then ammonia water is added to make the pH of the solution 5.0. The clinker obtained in Step 1 is mixed with the prepared mixed solution according to a liquid-solid ratio of 5:1 mL / g, and then leached at a leaching temperature of 90°C for 90 min to obtain a leaching solution containing iron, vanadium and nickel and a leaching residue of a silicon-aluminum salt molecular sieve with a crystal lattice structure, thereby removing the harmful metals of iron, vanadium and nickel, while preserving the microstructure of the waste catalyst particles and the structure of the Y-type molecular sieve, achieving the effect of regenerating the FCC catalyst.

[0067] The leaching rates of the harmful metals V, Fe and Ni are 75%, 43% and 12%, respectively, and the leaching rate of aluminum element is only 1%, which maximizes the content of alumina acid center in the FCC catalyst.

[0068] It can be seen from the scanning electron microscope observation that the appearance and Y-type molecular sieve structure of the activated FCC catalyst particles obtained in the embodiment are kept intact. It can be seen from the XRD analysis that the recovery process does not affect the crystalline morphology of the FCC catalyst.

[0069] Examples 4-7

[0070] The FCC waste catalyst is regenerated according to the method of Example 1, except that the conditions are as follows in Table 1, and the results are shown in Table 1.

[0071] Table 1

[0072]

[0073] It can be seen from the results in Table 1 that the regeneration method of the present application can achieve high metal leaching rate.

[0074] Examples 8-11

[0075] The FCC waste catalyst is regenerated according to the method of Example 1, except that the conditions are as follows in Table 2, and the results are shown in Table 2.

[0076] Table 2

[0077]

[0078] It can be seen from the above results that the metal leaching rate can be further improved by heat treatment at 80-140°C.

[0079] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A process for the regeneration of FCC spent catalyst, characterized in that, The method comprises the following steps: (1) The FCC spent catalyst is mixed with 4wt% hydrogen peroxide solution at a liquid-solid ratio of 1:1 mL / g, and then calcined in a microwave field at 110°C for 30 min to obtain clinker; (2) The clinker obtained in step (1) is mixed with an oxalic acid and ammonia water mixed solution at a liquid-solid ratio of 6:1 mL / g, and then acid leached at 50°C for 30 min, and then solid-liquid separation is performed to obtain the regenerated FCC catalyst; The mixed solution is obtained by adjusting the pH of 0.01M oxalic acid to 3 with ammonia water.

2. A process for the regeneration of FCC spent catalyst, characterized in that, The method comprises the following steps: (1) The FCC spent catalyst is mixed with 4wt% hydrogen peroxide solution at a liquid-solid ratio of 0.7:1 mL / g, and then calcined in a microwave field at 100°C for 40 min to obtain clinker; (2) The clinker obtained in step (1) is mixed with a dilute sulfuric acid solution with a pH of 4 at a liquid-solid ratio of 5:1 mL / g, and then acid leached at 70°C for 60 min, and then solid-liquid separation is performed to obtain the regenerated FCC catalyst.

3. A process for the regeneration of FCC spent catalyst, characterized in that, The method comprises the following steps: (1) The FCC spent catalyst is mixed with 3wt% hydrogen peroxide solution at a liquid-solid ratio of 0.7:1 mL / g, and then calcined in a microwave field at 80°C for 45 min to obtain clinker; (2) 0.01M sulfurous acid is stirred with aluminum hydroxide until the aluminum source is dissolved, and then ammonia water is added to make the pH of the mixed solution 5.0, and the clinker obtained in step (1) is mixed with the prepared mixed solution at a liquid-solid ratio of 5:1 mL / g, and then leached at 90°C for 90 min, and then solid-liquid separation is performed to obtain the regenerated FCC catalyst.

4. The regeneration method according to any one of claims 1 to 3, wherein In step (2), the regenerated FCC catalyst is a FCC catalyst silicon aluminum salt molecular sieve with a crystal lattice structure.

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