Can methanol catalysts be reused after being passivated?
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Can methanol catalysts be reused after being passivated? After being used for one year in an alcohol production facility, the catalyst was to be passivated and removed due to issues with the synthesis tower, in order to be reinstalled and restored for use. Is it feasible?
The passivation method for catalysts after reaching their service life is normal passivation, that is, high-temperature passivation. After the catalyst temperature was reduced to 90°C, the oxygen content was gradually increased, with the temperature rise controlled at 30°C/h. The maximum temperature shall not exceed 180°C. The oxygen concentration at the inlet and outlet is balanced, above 15%.
Recently, some units have carried out pressure vessel inspections on methanol synthesis towers, raising the question of whether catalysts can be used after being passivated.
No passivation is needed; just maintain pressure after cooling with nitrogen. It’s best to achieve thorough cooling to prevent oxidation due to the entry of air
If used for a short period of time, it can be reused, but its activity will definitely decrease.
It depends on whether methanol is the main product or part of an energy-saving recovery project; if it’s a secondary unit of such a recovery project, it’s okay not to invest in it. Catalyst passivation and re-reduction are theoretically feasible. But in reality, almost no one does this. After such treatment, a large amount of the catalyst gets pulverized and broken; passivation will inevitably affect its performance, and it’s difficult to achieve complete passivation, which may also lead to secondary accidents during the process. The cost of catalysts accounts for a very small portion of the total cost of producing methanol, making it not worthwhile to include it. When driving, a high pressure difference leads to increased energy consumption, reduced activity and thus lower output, as well as higher costs; it’s not cost-effective in the end. It’s better to get a new one; old catalysts can still be sold for a good price, and they also help reduce the cost of new catalysts. If the imported ones are expensive, use the domestic ones.
In fact, the passivation process of catalysts is a strong oxidation process; the specific surface area and pore structure of the catalysts change, and sintering may also occur. If reduction is attempted afterward, copper oxide cannot be fully reduced, resulting in a severe decline in its performance!
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