Variable catalysts in natural gas hydrogen production

In natural gas-based hydrogen production plants, the purpose of medium-pressure conversion is to further react the gas coming out of the conversion furnace, primarily to reduce the carbon monoxide content at the outlet to below 3%. The medium-temperature catalyst needs to be reduced before its first use.

Medium-temperature shift catalysts are primarily composed of Fe2O3 (in their factory state), and are reduced before use. Toxins: Arsenic, chlorine; Deactivation: Operating temperature exceeds the process specifications, and the catalyst ages and becomes inactive. The catalyst becomes deactivated due to overheating and caking. During startup and shutdown, when the temperature is below the steam condensation point, the catalyst becomes wet, disintegrates, and loses its activity. The catalyst must be passivated before unloading to prevent severe oxidation upon contact with air during unloading, which could cause burns to the operators. Passivation: Nitrogen is introduced into the medium-voltage inlet along with air; after that, the system is vented (or the air is circulated), with the space velocity to be no less than 800 h. The air volume is initially 5%, and it is increased gradually depending on the temperature rise; the initial passivation temperature should be below 280°C.