Magnetic separation of spent catalytic cracking catalyst

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Magnetic separation of spent catalytic cracking catalyst 1. Basic principles of magnetic separation technology: In the catalytic cracking production process, when the feed oil contacts the catalyst, the heavy metals in the feed oil (mainly Ni, Fe, V, Na, Ca, Cu, etc.) and the coke generated by the reaction are deposited on the catalyst particles. When the catalyst is regenerated, the coke on the catalyst particles is burned off, but the heavy metals remain. As the catalyst is continuously recycled in the system, the amount of heavy metals deposited on the catalyst continues to increase, causing the catalyst to be contaminated and poisoned. Due to the poisoning of the catalyst, its activity and selectivity decrease, product distribution deteriorates, and liquid recovery decreases. In order to maintain the appropriate activity and selectivity of the system catalyst, it is necessary to unload part of the balancer and replenish fresh catalyst. The discharged balancing agent contains catalyst particles with different service lives and varying amounts of heavy metal deposition. The catalyst particles with less heavy metal deposition still have higher activity and selectivity. If this part of the catalyst is effectively separated and recycled from those with heavy metal pollution, and then returned to the device for continued use, the consumption of the device's catalyst can be reduced and the environmental pollution of the spent catalyst can be reduced. Ni, Fe and V in the heavy metals that contaminate the catalyst are ferromagnetic and paramagnetic substances. Shows strong magnetism in a magnetic field. Therefore, in the magnetic field, the magnetism of catalyst particles with a short service life and low heavy metal content is weak, while the magnetism of catalyst particles with a long service life and high heavy metal content is strong. In a magnetic field with a certain intensity and gradient, the latter is adsorbed but the former is not, thereby achieving separation of the two. This part of the catalyst with low heavy metal content is recovered and can be returned to the device for continued use. This is the basic principle of magnetic separation. 2. The research and development process of magnetic separation: 1. Data research: Since 1996, we have conducted technical research on the research, testing, development and application of magnetic separation technology for catalytic cracking waste catalysts in the world, and have basically understood the basic situation of the research and development and industrial application of magnetic separation technology. 2. R&D test stage: Since 1997, we have researched and evaluated magnetic separation methods, screening of magnetic materials, and the possibility of realizing various methods, and selected the rare earth permanent magnet separation method with high magnetic field intensity and high magnetic field gradient. 3. Reagents for industrial prototypes: After numerous tests, we successfully developed the first rare earth permanent magnet catalyst separation prototype in 1998, with a capacity of 1 ton/day. 4. Use evaluation: We conducted a survey on catalytic cracking in more than 20 refineries across the country. And carry out sampling, separation, physical and chemical analysis, and small fluidized bed evaluation of the catalysts used. The waste catalysts with Ni content ranging from 2000ppm to 24000ppm were separated, and the results proved that the separation effect was obvious. 5. Industrial application test of magnetic separation: We jointly completed the magnetic separation industrial application test at Jinan Refinery from December 2000 to March 2001. (For details, see Petroleum Refining and Chemical Industry, Issue 8, 2003, P20) At the same time, from May 2001 to July 2001, we jointly conducted industrial verification tests with PetroChina Dagang Petrochemical Company (for details, see China Petroleum and Chemical Industry Science and Technology Information Guide, Volume 1, P45, 2002), and achieved encouraging results. 6. Industrialization: On the basis of industrial experiments, we designed a complete set of industrial solutions. In December 2002, Sinopec Jinan Branch first implemented the industrialization of magnetic separation technology for catalytic cracking waste catalysts. So far, it has been promoted and applied in eight refineries of Sinopec and Petroleum. 3. Industrial application of magnetic separation of spent catalysts: 1. Magnetic separation: *Determination of recovery rate: The recovery rate of low magnetic agent is the most fundamental indicator to ensure the quality of low magnetic agent. For different catalytic devices, their low magnetic agent recovery rates are different and cannot be generalized. For the same set of catalytic device, the recovery rate of low magnetic agent is also different in different periods of reuse. The basis for determining the recovery rate is:: Based on factors such as the nature of the raw materials of the catalytic unit, the processing plan, and the degree of heavy metal contamination of the balancing agent, a reasonable recovery rate is determined to ensure the quality of the low-magnetic agent and meet the process needs of the device after reusing the low-magnetic agent. ＊Quality management of magnetic separation: Each batch of balancing agents sent to magnetic separation must be sampled for physical and chemical analysis. During the magnetic separation process, low magnetic agents and balancing agents should be measured regularly using a magnetic balance. After each batch of balancing agents is separated, samples must be taken for physical and chemical index analysis, and a database must be established to ensure the recovery quality of low magnetic agents. 2. Device reuse: *The reuse of low-magnetic agent in the catalytic device must follow the principle of "replacement". Remove the device balance agent, add low magnetic agent, and replace the device balance agent with low magnetic agent. * Under the premise of ensuring normal production of the device, determine the reuse amount of the low magnetic agent. It is best to unload the balancing agent before adding the low magnetic agent each time, and then add the low magnetic agent. * Must adhere to the principle of continuous replacement of balancing agent with low magnetic agent without interruption. A sufficient amount of low-magnetic agent must be reserved before reuse. *According to the purpose of reusing low magnetic agent in the device, the amount of low magnetic agent and fresh catalyst should be reasonably determined. When the purpose is to save catalyst and reduce unit consumption, the recycling amount of low magnetic agent can be gradually increased and the amount of new agent added can be gradually reduced. It is best to increase or decrease these after the low magnetic dose of the device accounts for 30%, and the effect will be better. We solemnly recommend the latter reuse purpose, which can achieve better economic benefits.