Shutdown passivation of hydrogenation reactor
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The shutdown passivation of hydrogenation reactors is primarily aimed at preventing ferrous sulfide on the catalyst surface from coming into contact with oxygen and undergoing spontaneous reactions that convert ferrous sulfide into stable iron oxide and sulfur dioxide. Does it also serve to convert the catalyst from its sulfided state to its oxidized state? Can a catalyst that has been converted to a sulfided state be pre-sulfided again for reuse?
Was the last sentence not expressed clearly? I don’t want to ask: can the catalyst that has been converted to an oxidized state be pre-sulfurized again for reuse? The answer is yes.
I agree with everything you said. However, it’s hard to say exactly how much of the passivation process involves the formation of oxidized states. Catalyst manufacturers say that at low temperatures, around 100 degrees Celsius, only the first scenario occurs – namely the decomposition of FeS. To convert it into oxidized states, high-temperature passivation is required; I vaguely remember the temperature to be above 220 degrees Celsius. On the other hand, even with low-temperature passivation, I still carry out pre-sulfidization at the start of operation to ensure activity; I think that in some areas there will inevitably be some conversion to oxidation states due to high temperatures. . .