Reasons for MTBE catalyst deactivation and technical requirements for raw materials

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This post was last edited by bhdjj on 2010-8-17 at 16:44. 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 from 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 brought in from 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. —The alkaline substances and nitrogen-containing compounds in the raw materials can react with the sulfonic acid groups of the catalyst, thereby deactivating the catalyst. —SO3-H+] + NH3 —SO3-H+] + 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. —SO3-H+] + CH3-S-CH3 + H+. 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 reactants 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 basic pollutants 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.