MTBE unit catalyst maintenance
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The MTBE plant has been shut down, and the materials in the plant, namely methanol and C4, are being removed from it. I would like to ask experienced sea friends how to maintain the catalyst inside the container to prevent it from failing How to determine if a catalyst has failed? Thank you, big red flower reward! !
Preventing catalyst failure in the maintenance container? inerting
This post was last edited by *aojiaoya0546 on 2015-9-14 20:45. I heard that it needs to be soaked in demineralized water; it loses its effectiveness once it dries out, but I don’t understand why
Excerpt from bhdjj@bhdjj (ID 365704): http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=717997&highlight=MTBE%B4%DF%BB%AF%BC%C1 1. Reasons for catalyst deactivation The active groups in a catalyst are the sulfonic acid groups (-SO3-H+) present therein; the replacement of hydrogen atoms on these groups by other groups present in the reactants, or the loss of these sulfonic acid groups, can lead to a decrease in the activity of the resin catalyst, and in severe cases, to its deactivation. Based on research on resins conducted both domestically and internationally, the main reasons for this phenomenon can be summarized as follows. 1) Impurity ions carried in the raw materials undergo ion exchange with the catalyst, causing the hydrogen ions on the sulfonate group to be replaced and thereby deactivating that sulfonate group. +M +-------------- +H+ 2) Alkaline substances and nitrogen-containing compounds in the raw materials can react with the sulfonic acid groups of the catalyst, thereby deactivating it. + NH3 + NaOH + H2O: Ethanolamine desulfurization makes use of an aqueous solution of monoethanolamine; when this solution enters the catalyst bed, it causes the catalyst to become inactive. -SO3H++ NH2CH2CH2OH—— －SO3NH3CH2CH2OH 3) Various organic and inorganic sulfides can react with the sulfonic acid groups in the resin, thereby deactivating the catalyst. + CH3-S-CH3 + H+ 4) The dienes and olefins present in the raw materials polymerize in the microvoids of the resin, resulting in polymers with higher molecular weights. These polymers block the pores through which materials can enter and exit the resin, preventing the reaction materials from reaching the active groups within the resin and thus causing the resin to lose its activity. 2. The requirements for the impurity content in C4 feedstock are as follows: (1) The total amount of organic base contaminants must be kept below 5 ppm ； (2) The total amount of metal ion pollutants should be kept below 1 ppm ； (3) The diene content should be kept below 100 ppm. Understanding these indicators is of practical significance for designing or modifying MTBE process routes. To keep the metal ions and alkaline substances in the feedstock tetrahydrocarbons within specified limits, it is necessary to improve the management of washing and water separation processes.
Excerpt from Liu Jingguo @Liu Jingguo (ID 20383): http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=531764&highlight=MTBE%B4%DF%BB%AF%BC%C1 Criteria for determining catalyst deactivation: 1. If the conversion rate is below 90%, the catalyst must be replaced. 2. If the isobutylene content after etherification exceeds 3%, the catalyst needs to be replaced as well. 3. If the temperature rise in the reactor bed is less than 10 degrees, the catalyst is no longer effective. 4. Some etherification catalysts experience temporary deactivation toward the end of the reaction process; it’s best to replace them anyway. 5. Catalysts aren’t very expensive – a few tons of M are sufficient to replace them
Be sure to wait until the bed temperature drops below 40°C before stopping the circulation pump or the reflux pump; at that point, the material has essentially completed its reaction, so not much heat will be released, which will prevent the catalyst from overheating. After material withdrawal, the equipment can be protected by a slight positive pressure.
How can the catalyst be protected if it needs to be removed from the equipment?»
Do you mean to store it after the catalyst is removed? First, wash it with methanol, then with deionized water, and finally blow dry the catalyst surface with nitrogen before removing it for storage.
Before shutting down, it was possible to determine based on the reaction progress whether the catalyst had become ineffective; otherwise, the operation would not have been stopped and the contents emptied.
Storing catalyst off-gas is not very feasible. Either store it under N2 seal in the reactor. Either replace the catalyst.
I don’t know what basis there is for the claim about the 8th floor?