How is hydrogen production catalyst deactivation carried out, and how much heat is released during the deactivation process?

First, pure water is passed through to cool and clean the system; then ordinary nitrogen is introduced, followed by compressed air. Throughout this process, process water continues to flow, and the oxygen content is monitored

After some catalysts in the hydrogen production unit become deactivated, they must be removed and replaced to meet production requirements; meanwhile, some catalysts (such as medium-pressure shift and hydrogenation catalysts) still possess high free energy, and come into contact with air easily, leading to oxidation, temperature rise, and ignition； Due to carbon deposition and coking that occur during use, it is difficult to remove the conversion catalyst directly ； To achieve safe catalyst discharge, it is necessary to treat a portion of the catalyst accordingly before discharging it. Under the reaction conditions, the conversion catalyst can be deactivated by simply stopping the feed of oil and allowing steam to come into contact with the catalyst alone for about ten minutes. To preserve the low-temperature reduction performance of the catalyst, the temperature during passivation is generally slightly lower than the operating temperature in normal production. The medium-temperature catalyst, which has been reduced to active Fe3O4, still has a high surface free energy even after being in use for several years and reaching the end of its useful life; upon direct contact with air, it will ignite violently immediately. Therefore, it must be passivated before it can come into contact with air. After stopping the process gas and releasing pressure, when the bed temperature drops to 200°C, steam is introduced into the medium-temperature reactor from the medium-temperature start-up header to completely displace H2 and CO from the bed, reducing their concentration to <0.50%. (3) Control the steam pressure to be 0.05 MPa lower than that of the purge air; open the purge air valve to introduce purge air into the bed. Closely monitor changes in the bed temperature; if the temperature rise of the bed exceeds 30°C, immediately reduce the amount of purge air and increase steam flow to cool it down. (4) If the temperature rise of the bed is not significant, the volume of cleaning air can be increased gradually. Pay close attention to changes in the bed temperature, ensuring that the temperature rise remains at ≤40°C/h and that the peak temperature in the bed does not exceed 400°C. If the temperature rises too quickly, immediately reduce the flow rate of the purification air valve and decrease the steam supply to cool down; this method is used for passivation. Until the purge air is fully opened and the steam is fully closed, with no temperature rise in the bed layer, and after staying stable for 1–2 hours, the passivation is complete. (5) Continue to supply purified air to lower the bed temperature below 50°C. (6) Criteria for the end of passivation