Regarding cracking vulcanization and passivation issues
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Sulfidation passivation is generally carried out before starting up the process. So, if the catalyst remains highly active after startup, is passivation still necessary? Is the catalyst sulfidation process controllable? It is to sulfide the catalyst to the desired activity level.
Firstly, catalyst deactivation during pre-sulfurization is done to meet the requirements for high-temperature pre-sulfurization of the catalyst; without reaching this temperature, the catalyst will not be sufficiently sulfured, which affects subsequent hydrogenation performance. In normal production, the high activity of cracking catalysts can be controlled by adjusting the nitrogen content in the feedstock, and generally no deactivating agents are used； The pre-sulfidation process of the catalyst is controllable, and can be regulated by controlling the temperature and the amount of sulfur added.
If the activity is high and the nitrogen content in the raw materials is not high either, the book states that it is possible to consider adding a passivator; in fact, a passivator can even be added to modify the product profile. It’s written in the book, but we have never actually operated our device