After the catalyst is loaded
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After the catalyst is loaded and in contact, heating for reduction is not planned. Is nitrogen protection needed at this time? Why? Are there any other things for moisture protection? There’s no need to worry about oxygen and CO2; is there anything else to worry about?
It is best to use nitrogen protection, mainly to prevent moisture; in addition, it also prevents air from entering and causing corrosion of the equipment and pipelines.
Catalysts generally consist of a carrier, an activator aid, and an active agent, and have a complex structure; prolonged exposure to air can degrade the catalyst’s activity. It must be nitrogen-sealed.
How to destroy it? What is the mechanism? Those in all oxidation states should be quite stable.
Nitrogen protection is primarily used to prevent moisture; since the air contains various components, a catalyst exposed to air for an extended period can easily undergo slow reactions with trace amounts of elements such as S, Cl, Fe, etc., resulting in its deactivation. It’s rare, but it’s still a loss. Moreover, after the catalyst is filled without nitrogen encapsulation, its bulk density increases, making it difficult for heat to be dissipated; once it reaches a certain level, it will undergo a reduction reaction with H in the air.
Air entering the equipment and pipes undergoes an oxidation reaction with metal, causing corrosion of the equipment and pipes!
If the catalyst is in an oxidized state, for the catalyst itself, the main purpose of nitrogen sealing is to prevent moisture from entering. Dry air alone has little effect on catalysts in their normal temperature state; the concern regarding a loss of catalyst activity stems mainly from the fact that if the air contains certain components that are harmful to the catalysts – such as those found in air from chemical plants, like Cl, S, heavy metal ions, and acids – these substances can easily adsorb onto the catalysts, thereby causing changes in their performance. So, as a precaution, it’s better to use nitrogen sealing. Another adverse effect of air is on the reactor equipment; prolonged exposure to components such as oxygen in the air can cause oxidation and corrosion of the reactor, which has nothing to do with the catalyst itself.
If nitrogen is available, it is best to use nitrogen for sealing; in the absence of such a system, measures must be taken to prevent moisture from entering, such as using blind flanges and other protective devices.
Reply to 1# lizhaoye: It only has a moisture-proof effect; there’s no need to worry about it for short periods of time (a few days). The catalyst is in an oxidized state and possesses excellent stability; once oxidation is complete, nitrogen sealing is not necessary at all if the system is dry. In other words, even for long-term storage, sealing with dry air (instrument air) can be considered
Moisture prevention is of the utmost importance, as it affects the structural strength and shape of the catalyst. Additionally, it is necessary to prevent rusting within the system, as it becomes very difficult to clean the catalyst once it has been installed there. Rust forms on the surface of the catalyst during production, causing waxing.
Well, it needs to be nitrogen-sealed to prevent air from entering, as that would cause chemical reactions in the catalyst