Hydrogenation catalysts: differences between metallic, oxidized, and sulfided states
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I would like to ask fellow sailors: some hydrogenation processes require catalysts in their metallic, oxidized, or sulfided state, while some hydrogenation catalysts need to be sulfided, and others require pretreatment via hydrogen reduction. Could you tell me what type of hydrogenation process requires which form of hydrogenation catalyst?
Hydrogenation catalysts are inactive in their oxidized state; only in their sulfided state do they exhibit hydrogenation activity, stability, and selectivity. During sulfidation, it is necessary to control the hydrogen sulfide concentration to prevent the catalyst from being reduced from its oxidized state back to its metallic form.
I would like to ask: there are also some catalysts that need to be reduced to their metallic state using hydrogen first. What types of hydrogenation reactions require the catalyst to be in a sulfided state, or in a metallic state?
I remember that the catalysts used for hydrogen production seem to require reduction, while the catalysts we use for hydrogenation all need to be sulfided in an oxidized state; there are none that require reduction~~~~
Selective hydrogenation of olefins and alkynes should occur in the metallic state, while hydrodesulfurization should take place in the sulfided state
The metals in the hydrogenation catalysts leaving the factory are all in oxidized states. Since catalysts in their oxidized state have low activity and poor stability, they must first be oxidized or reduced. Hydrogenation catalysts that are not precious metals and are used for refining/modifying/cracking require pre-sulfurization before use, as the feedstock contains high levels of sulfur. Precious metals and catalysts used for isomerization, reforming, etc. are reduced before use; since the raw materials contain no sulfur, the catalysts do not become sulfided either. This is just my personal opinion; if there are any mistakes, I hope fellow netizens can point them out