Why is the catalyst sulfided, and when is sulfiding considered complete?
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Why is the catalyst sulfided, and when is sulfiding considered complete?
CO conversion catalysts are generally in an oxidized state and inactive before leaving the factory; they must be sulfided to a sulfide state in order to become active. The specific vulcanization plan should be provided by the catalyst manufacturer.
This post was last edited by wlq1970 on 2015-6-22 09:23. Catalysts are generally in an oxidized state when they leave the factory; there are also pre-reduced versions, but the filling process is quite complicated and requires specialized companies to carry out. For catalysts in the oxidized state, heating is carried out after filling, after which sulfidation begins. Sulfidation typically takes place in an initial phase, a main phase, and a strengthening phase. The completion of sulfidation can be determined by ensuring that the hydrogen sulfide level at the outlet is equal to that at the inlet, and that the carbon dioxide level at the outlet is equal to the carbon dioxide level at the inlet plus the carbon dioxide generated as a result of the reaction. The intensification phase must be no less than 2 hours.
The oxidized state is inactive; it requires the sulfided state to be active. When raising the temperature, it is important to maintain a constant temperature, primarily to ensure the stability of the catalyst under such conditions and to keep temperature differences minimal.
This is generally indicated by the H2S content at the furnace outlet, with specific figures provided in the manufacturer’s instructions. Additionally, so-called enhanced vulcanization (increasing temperature and pressure) is generally carried out toward the end of the vulcanization process
Hydrogenation reaction catalysts oxidize when exposed to air, a process also known as passivation; after being installed in the system, they need to be sulfided, as only in their sulfided state do they possess hydrogenation activity. Theoretically, hydrogen sulfide is consumed during the sulfidation process, and it ends when the hydrogen sulfide concentration at the inlet and outlet of the reactor is the same.
Catalysts resistant to sulfur shift are like this; those not resistant to sulfur shift are different
Sulfidation is carried out to activate the catalyst; the completion of sulfidation is generally indicated by the change in hydrogen sulfide levels at the inlet and outlet