Bioleaching circulating cleaning method for repairing and regenerating waste FCC (Fluid Catalytic Cracking) catalyst
Through bio-leaching technology, active effluent is prepared in membrane bioreactors, and waste FCC catalysts are cleaned and repaired, which solves the problems of reduced catalyst activity and waste of resources, and realizes efficient regeneration of catalysts and recovery of metal resources.
Patent Information
- Application Number
- CN202411730217.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-03-11
AI Technical Summary
The prior art is difficult to effectively repair and regenerate waste fluidized catalytic cracking (FCC) catalysts, resulting in reduced catalyst activity and waste of resources.
Using bio-leaching technology, a characteristic active leach solution is prepared by cultivating autotrophic sulfur oxidized bacteria in a membrane bioreactor, which is used to clean and repair waste FCC catalysts to achieve the recovery of its structural integrity and catalytic activity.
While ensuring the structural integrity of the catalyst, the catalytic activity and specific surface area of the waste FCC catalyst are successfully improved, the wastewater generation is reduced, the regeneration cost is reduced, and the efficient recovery of metal resources is achieved.
Abstract
Description
Technical Field
[0001] The present technology relates to a method for green cleaning of waste FCC catalysts by bioleaching and repairing the activity of the regenerated catalyst, and belongs to the intersection of high-value resource utilization technology for material source-related heavy and hazardous waste, environmental microbial technology and biochemical engineering. Technical Background
[0002] Catalysts are widely used in many industries such as petrochemicals, coal chemicals, pharmaceutical manufacturing, automobile exhaust purification, flue gas denitrification, etc. Fluid catalytic cracking is one of the most important core processes in the modern heavy oil refining industry. It is a thermochemical process in which heavy oil is catalytically cracked to produce light oil under the action of FCC catalyst at a certain temperature. Generally, FCC catalysts are composed of Y zeolite, matrix materials and binders, among which Y zeolite provides most of the catalytic cracking activity with its rich active sites and super cage structure. During long-term use, FCC catalysts interact with external environmental substances, and their structure and physicochemical properties change, resulting in a gradual decrease in catalytic activity and eventual failure. Carbon deposition, hydrothermal action, nitride poisoning, sulfide poisoning and metal poisoning can all cause catalyst deactivation, especially metal poisoning. During the catalytic cracking process of heavy oil, the impurity elements nickel, vanadium, iron, etc. contained in it accumulate on the surface and inside of the FCC catalyst, resulting in a decrease in specific surface area, a decrease in catalytic activity, and a continuous attenuation of catalytic efficiency. Currently, the world produces millions of tons of waste FCC catalysts each year, accounting for 50% of the total waste catalysts. Because they contain a variety of toxic metals, waste FCC catalysts are listed as hazardous wastes by various countries and are a typical type of material source involving heavy hazardous wastes. The large-scale disposal and discharge of waste FCC catalysts not only pose serious potential environmental risks but also cause great waste of metal resources. Therefore, the repair and regeneration of waste FCC catalysts is of great significance for the high-value utilization of waste FCC catalysts, the short-process circulation of metal resources, the pollution control of toxic metals, and the energy conservation and carbon reduction of the petrochemical industry.
[0003] At present, the commonly used process for repairing and regenerating spent FCC catalysts is magnetic separation, which uses magnetic differences to separate low-magnetic agents with low iron and nickel accumulation from highly polluted materials to achieve FCC regeneration. Although the magnetic separation process has the characteristics of low energy consumption, low cost, and no wastewater, it can only achieve an FCC regeneration recovery rate of about 20%; and this process only has a separation effect on magnetic elements such as iron and nickel, and has almost no effect on elements such as vanadium, calcium, and magnesium. Another waste FCC catalyst regeneration process is inorganic-organic mixed acid cleaning. Mixed acid cleaning can remove a variety of exogenous deposited metals and significantly increase the specific surface area of the regenerated product; but inorganic strong acids mainly based on sulfuric acid will cause serious loss of aluminum and silicon in the catalyst body and damage to the main structure, while expensive organic acids will lead to a significant increase in the cost of repair and regeneration, and at the same time produce a large amount of difficult-to-treat acidic organic wastewater, which further increases the cost and difficulty of chemical regeneration of spent FCC.
[0004] Bioleaching refers to the process in which microorganisms use their own acid hydrolysis, oxidation, reduction and complexation of their metabolites to dissolve the target metals in the solid phase and enter the liquid phase. It has the characteristics of simple equipment, easy operation, economic efficiency and environmental friendliness. The present invention uses the green, mild and low-carbon process characteristics of bioleaching technology to achieve selective bioleaching of exogenous deposited elements and biological cleaning and regeneration of waste FCC catalysts while ensuring the integrity of the FCC catalyst structure and low loss of bulk elements. At the same time, the cyclic cleaning of waste FCC catalysts is achieved through the efficient regeneration of failed leachate, so as to greatly reduce the amount of wastewater generated, increase the enrichment concentration of metals and improve the difficulty of subsequent metal separation and recovery. Summary of the invention
[0005] This technology maintains the integrity of the basic structure of the spent FCC catalyst and the low loss of the main structural elements such as aluminum and silicon, while achieving the selective bioleaching, cyclic cleaning and liquid phase enrichment of exogenous deposited metals such as iron, nickel and vanadium, and ultimately achieving the active repair and green regeneration of the spent FCC catalyst. The purpose of the present invention is achieved through the following technical solutions.
[0006] A method for green biological cleaning and active repair and regeneration of spent FCC catalysts, characterized by comprising the following steps:
[0007] (1) Continuous preparation of active leachate for cleaning waste FCC catalysts. Add basic inorganic salt culture medium and sulfur (1.0%-5%), waste sulfur (1.0%-10%), waste sulfur paste (1.0%-10%) and other inorganic energy substrates containing low-valent sulfur or elemental sulfur to a membrane bioreactor (MBR, membrane pore size 0.1-0.6 micron, membrane material includes ceramic membrane, inorganic membrane, organic membrane or composite membrane), and inoculate autotrophic sulfur oxidizing strains or composite bacteria (inoculation amount 5%-20%). The culture temperature is 20-40°C, the stirring speed is 20-100 rpm, the aeration volume is 0.10-1.0 reactor volume / minute, and 0.5-2.0 reactor volumes of active leachate are extracted through the membrane every day, and inorganic salt culture medium is supplemented simultaneously to achieve a balance between influent and effluent. The prepared special active leachate has the following characteristics: pH value 0.4-1.5, total concentration of small molecule organic acid 50-500 mg / L, and total concentration of extracellular polymers 50-500 mg / L.
[0008] (2) Active leachate cleaning of spent FCC catalyst. Active leachate is injected into the cleaning tank and the spent FCC catalyst is added for bioleaching cleaning. The solid-liquid ratio is 10%-30%, the temperature is 30-80°C, the time is 4.0-12 hours, or low-speed mechanical stirring is 10-40 rpm or aeration stirring is 0.05-0.2 reactor volume / minute. Sodium carbonate (1-5g / L), sodium nitrate (1-5g / L), urea (1-5g / L), oxalic acid (1-5g / L), citric acid (1-5g / L), EDTA (1-5g / L) and other cleaning aids are added, or ultrasonic assistance (0.1-0.5kw / cubic) is applied. The leaching rate of iron is 10-50%, the leaching rate of vanadium is 20-60%, the leaching rate of nickel is 10-50%, the leaching rate of calcium is 20-60%, the loss rate of aluminum is ≤10%, the loss rate of silicon is ≤5%, the structural integrity rate is ≥85%, the catalytic activity is increased by 5-20%, and the specific surface area is increased to 150-250m 2 / g.
[0009] (3) Reflux regeneration of spent leachate and cyclic cleaning of spent FCC catalyst. After biological cleaning of spent FCC catalyst is completed, solid-liquid separation is performed by filter pressing, suction filtration or centrifugation. The regenerated FCC after separation is deeply washed with tap water or distilled water to remove attached impurities such as acid, salt and organic matter, and the washing wastewater (fresh water) is collected; the separated leaching waste liquid (spent leachate) is directly injected into the MBR as influent and the balance of influent and effluent water is maintained and the indicators of active leachate (effluent) meet the standards. Circular cleaning is performed according to step (2). After 3-6 cycles, the metal-enriched spent leachate is opened for metal extraction and recovery, and fresh water (with inorganic salt culture medium added) is used to replenish water for the next round of cyclic cleaning.
[0010] The beneficial effect of the present invention is that the biologically active leachate prepared continuously, controllably and efficiently by MBR can be used for green cleaning and repair and regeneration of waste FCC catalysts under mild working conditions; at the same time, the regeneration and cyclic cleaning of the failed leachate can greatly reduce the amount of wastewater generated and its treatment costs, thereby improving the overall economic benefits of the biological cleaning technology. In addition, the metal-enriched liquid from the cyclic cleaning also creates favorable conditions for the subsequent separation and recovery of valuable metals. DETAILED DESCRIPTION
[0011] The present invention is described in detail below in conjunction with implementation examples.
[0012] Embodiment 1:
[0013] In a membrane bioreactor (MBR, membrane pore size 0.45 micron, PVDF membrane), basic inorganic salt culture medium and waste sulfur (concentration 5%) were added to inoculate sulfur-oxidizing composite bacteria (inoculation amount 20%). The culture temperature was 30°C, the stirring speed was 60 rpm, the aeration volume was 0.2 reactor volume / min, 0.5 reactor volume of active leachate was extracted through the membrane every day and inorganic salt culture solution was supplemented simultaneously to achieve the balance of influent and effluent. The pH value of the prepared active leachate was 0.5, the total concentration of small molecule organic acids was 150 mg / L, and the total concentration of extracellular polymers was 300 mg / L. The waste FCC catalyst was cleaned by biological leaching in a cleaning tank, with a solid-liquid ratio of 20%, a temperature of 50°C, a mechanical stirring of 30 rpm, sodium nitrate (concentration 2g / L) and ultrasonic assistance (0.1kw / cubic). After 10 hours of cleaning, the iron leaching rate is 25%, the vanadium leaching rate is 40%, the nickel leaching rate is 20%, the calcium leaching rate is 50%, the aluminum loss rate is 10%, the silicon loss rate is 2%, the structural integrity rate is 85%, the catalytic activity is increased by 15%, and the specific surface area is 200m 2 / g. After biological cleaning of spent FCC catalyst is completed, solid-liquid separation is performed by centrifugation. The regenerated FCC after separation is deep washed, and the leached waste liquid (failed leachate) is injected into the MBR as influent for regeneration and cyclic cleaning. After 3 cycles, the failed leachate is open-circuited.
[0014] Example 2: In a membrane bioreactor (MBR, membrane pore size 0.45 micron, PVDF membrane), basic inorganic salt culture medium and waste sulfur paste (concentration 6%) were added and inoculated with sulfur oxidizing composite bacteria (inoculation amount 20%). The culture temperature was 30°C, the stirring speed was 50 rpm, the aeration volume was 0.2 reactor volume / min, 0.5 reactor volume of active leachate was extracted through the membrane every day and inorganic salt culture solution was supplemented simultaneously to achieve the balance of influent and effluent. The pH value of the prepared active leachate was 0.6, the total concentration of small molecule organic acids was 200 mg / L, and the total concentration of extracellular polymers was 350 mg / L. The waste FCC catalyst was cleaned by biological leaching in a cleaning tank, with a solid-liquid ratio of 15%, a temperature of 50°C, a mechanical stirring of 30 rpm, urea (concentration 2g / L) was added, and ultrasonic assistance (0.1kw / cubic) was applied. After 10 hours of cleaning, the iron leaching rate is 20%, the vanadium leaching rate is 50%, the nickel leaching rate is 20%, the calcium leaching rate is 40%, the aluminum loss rate is 8%, the silicon loss rate is 2%, the structural integrity rate is 90%, the catalytic activity is increased by 10%, and the specific surface area is 200m 2 / g. After the biological cleaning of the spent FCC catalyst is completed, solid-liquid separation is performed by suction filtration. The regenerated FCC after separation is deep washed, and the leached waste liquid (failed leachate) is injected into the MBR as influent for regeneration and cyclic cleaning. After 3 cycles, the failed leachate is open-circuited.
[0015] Example 3: In a membrane bioreactor (MBR, membrane pore size 0.40 micron, polytetrafluoroethylene membrane), basic inorganic salt culture medium and sulfur (concentration 2%) were added and sulfur oxidizing strains (inoculation amount 20%) were inoculated. The culture temperature was 30°C, the stirring speed was 50 rpm, the aeration volume was 0.2 reactor volume / min, 0.5 reactor volume of active leachate was extracted through the membrane every day and inorganic salt culture solution was supplemented simultaneously to achieve a balance between influent and effluent. The pH value of the prepared active leachate was 0.5, the total concentration of small molecule organic acids was 200 mg / L, and the total concentration of extracellular polymers was 350 mg / L. The bioleaching cleaning of the spent FCC catalyst was carried out in a cleaning tank, with a solid-liquid ratio of 10%, a temperature of 50°C, a mechanical stirring of 30 rpm, the addition of urea (concentration 3 g / L) and ultrasonic assistance (0.15 kw / cubic meter). After 8 hours of cleaning, the iron leaching rate is 25%, the vanadium leaching rate is 45%, the nickel leaching rate is 15%, the calcium leaching rate is 40%, the aluminum loss rate is 8%, the silicon loss rate is 3%, the structural integrity rate is 90%, the catalytic activity is increased by 5%, and the specific surface area is 180m 2 / g. After the biological cleaning of the spent FCC catalyst is completed, solid-liquid separation is performed by suction filtration. The regenerated FCC after separation is deep washed, and the leached waste liquid (failed leachate) is injected into the MBR as influent for regeneration and cyclic cleaning. After 4 cycles, the failed leachate is open-circuited.
[0016] Example 4: In a membrane bioreactor (MBR, membrane pore size 0.45 micron, polytetrafluoroethylene membrane), basic inorganic salt culture medium and waste sulfur (concentration 5%) were added and sulfur oxidizing bacteria (inoculation amount 20%) were inoculated. The culture temperature was 35°C, the stirring speed was 50 rpm, the aeration volume was 0.1 reactor volume / minute, 0.9 reactor volume of active leachate was extracted through the membrane every day and inorganic salt culture solution was supplemented simultaneously to achieve a balance between influent and effluent. The pH value of the prepared active leachate was 0.7, the total concentration of small molecule organic acids was 250 mg / L, and the total concentration of extracellular polymers was 400 mg / L. The waste FCC catalyst was cleaned by bioleaching in a cleaning tank, with a solid-liquid ratio of 15%, a temperature of 60°C, a mechanical stirring of 30 rpm, oxalic acid (concentration 2g / L) was added, and ultrasonic assistance (0.15kw / cubic) was applied. After 10 hours of cleaning, the iron leaching rate is 20%, the vanadium leaching rate is 50%, the nickel leaching rate is 20%, the calcium leaching rate is 50%, the aluminum loss rate is 10%, the silicon loss rate is 3%, the structural integrity rate is 95%, the catalytic activity is increased by 8%, and the specific surface area is 200m 2 / g. After the biological cleaning of the spent FCC catalyst is completed, solid-liquid separation is performed by suction filtration. The regenerated FCC after separation is deep washed, and the leached waste liquid (failed leachate) is injected into the MBR as influent for regeneration and cyclic cleaning. After 3 cycles, the failed leachate is open-circuited.
Claims
1. A method for green biological cleaning and active regeneration of spent FCC catalysts, characterized in that The following steps are involved: (1) Continuous preparation of active leachate for cleaning waste FCC catalysts. Add basic inorganic salt culture medium and sulfur (1.0%-5%), waste sulfur (1.0%-10%), waste sulfur paste (1.0%-10%) and other inorganic energy substrates containing low-valent sulfur or elemental sulfur to the membrane bioreactor (MBR, membrane pore size 0.1-0.6 micron, membrane material includes ceramic membrane, inorganic membrane, organic membrane or composite membrane), and inoculate autotrophic sulfur oxidizing strains or composite bacteria (inoculation amount 5%-20%). The culture temperature is 20-40℃, the stirring speed is 20-100 rpm, the aeration volume is 0.10-1.0 reactor volume / minute, and 0.5-2.0 reactor volumes of active leachate are extracted through the membrane every day, and inorganic salt culture medium is supplemented simultaneously to achieve a balance between influent and effluent. The prepared special active leachate has the following characteristics: pH value 0.4-1.5, total concentration of small molecule organic acids 50-500 mg / L, and total concentration of extracellular polymers 50-500 mg / L. (2) Active leachate cleaning of spent FCC catalyst. Active leachate is injected into the cleaning tank and the spent FCC catalyst is added for bioleaching cleaning. The solid-liquid ratio is 10%-30%, the temperature is 30-80°C, the time is 4.0-12 hours, or low-speed mechanical stirring is 10-40 rpm or aeration stirring is 0.05-0.2 reactor volume / minute. Sodium carbonate (1-5g / L), sodium nitrate (1-5g / L), urea (1-5g / L), oxalic acid (1-5g / L), citric acid (1-5g / L), EDTA (1-5g / L) and other cleaning aids are added, or ultrasonic assistance (0.1-0.5kw / cubic) is applied. The leaching rate of iron is 10-50%, the leaching rate of vanadium is 20-60%, the leaching rate of nickel is 10-50%, the leaching rate of calcium is 20-60%, the loss rate of aluminum is ≤10%, the loss rate of silicon is ≤5%, the structural integrity rate is ≥85%, the catalytic activity is increased by 5-20%, and the specific surface area is increased to 150-250m 2 / g. (3) Reflux regeneration of spent leachate and cyclic cleaning of spent FCC catalyst. After biological cleaning of spent FCC catalyst is completed, solid-liquid separation is performed by filter pressing, suction filtration or centrifugation. The regenerated FCC after separation is deeply washed with tap water or distilled water to remove attached impurities such as acid, salt and organic matter, and the washing wastewater (fresh water) is collected; the separated leaching waste liquid (spent leachate) is directly injected into the MBR as influent and the balance of influent and effluent water is maintained and the indicators of active leachate (effluent) meet the standards. Circular cleaning is performed according to step (2). After 3-6 cycles, the metal-enriched spent leachate is opened for metal extraction and recovery, and fresh water (with inorganic salt culture medium added) is used to replenish water for the next round of cyclic cleaning.
2. The method according to claim 1, characterized in that: Continuous preparation of active leachate for cleaning waste FCC catalysts. Add basic inorganic salt culture medium and sulfur (1.0%-5%), waste sulfur (1.0%-10%), waste sulfur paste (1.0%-10%) and other inorganic energy substrates containing low-valent sulfur or elemental sulfur to the membrane bioreactor (MBR, membrane pore size 0.1-0.6 micron, membrane material including ceramic membrane, inorganic membrane, organic membrane or composite membrane), and inoculate autotrophic sulfur oxidizing strains or composite bacterial flora (inoculation amount 5%-20%).
3. The method according to claim 1, characterized in that: The culture temperature is 20-40℃, the stirring speed is 20-100 rpm, the aeration volume is 0.10-1.0 reactor volume / minute, and 0.5-2.0 reactor volumes of active leachate are extracted through the membrane every day and inorganic salt culture solution is added simultaneously to achieve the balance of influent and effluent. The characteristics of the prepared special active leachate are: pH value 0.4-1.5, total concentration of small molecule organic acid 50-500 mg / L, and total concentration of extracellular polymers 50-500 mg / L.
4. The method according to claim 1, characterized in that: Active leachate is used to clean the spent FCC catalyst. Active leachate is injected into the cleaning tank and the spent FCC catalyst is added for bioleaching cleaning. The solid-liquid ratio is 10%-30%, the temperature is 30-80℃, the time is 4.0-12 hours, or the low-speed mechanical stirring is 10-40 rpm or the aeration stirring is 0.05-0.2 reactor volume / minute.
5. The method according to claim 1, characterized in that: Add cleaning aids such as sodium carbonate (1-5g / L), sodium nitrate (1-5g / L), urea (1-5g / L), oxalic acid (1-5g / L), citric acid (1-5g / L), EDTA (1-5g / L) or apply ultrasonic assistance (0.1-0.5kw / cubic meter) to enhance bioleaching cleaning.
6. The method according to claim 1, characterized in that: The leaching rate of iron is 10-50%, the leaching rate of vanadium is 20-60%, the leaching rate of nickel is 10-50%, the leaching rate of calcium is 20-60%, the loss rate of aluminum is ≤10%, the loss rate of silicon is ≤5%, the structural integrity rate is ≥85%, the catalytic activity is increased by 5-20%, and the specific surface area is increased to 150-250m 2 / g.
7. The method according to claim 1, characterized in that: Reflux regeneration of spent leachate and cyclic cleaning of spent FCC catalyst. After biological cleaning of spent FCC catalyst is completed, solid-liquid separation is performed by filter pressing, suction filtration or centrifugation. The regenerated FCC after separation is deeply washed with tap water or distilled water and the washing wastewater (fresh water) is collected; the separated leaching waste liquid (spent leachate) is injected into the MBR as influent for regeneration. The regenerated active leachate is cyclically cleaned. After 3-6 cycles, the metal-enriched spent leachate is opened for metal extraction and recovery, and fresh water (with inorganic salt culture medium added) is used to replenish water for the next round of cyclic cleaning.