One question per day: Methanol and purification technology forum version, 20180809

Advanced alkanes clog the catalyst’s micropores

Reasons for the decline in methanol synthesis catalyst activity: 1. Catalyst poisoning； 2. Too low air velocity, resulting in overheating and aging of the catalyst ； 3. Excessive production load or overly strict control of the temperature in the methanol synthesis reaction leads to catalyst aging ； 4. Frequent start-stop operations or other operational factors that cause the catalyst to become fragmented.

Improper temperature control, with fluctuations in temperature or excessively high temperatures, can severely affect the catalyst’s activity and shorten its lifespan. Frequent start-up and shutdowns cause considerable damage to catalyst activity. If the syngas is not replaced in a timely manner due to improper handling, or if there is a failure in the circulation pump that results in the cessation of syngas flow within the tower, the formation of carbonyl metal compounds becomes inevitable under such a carbonyl-rich atmosphere at low temperatures. As a result, every time the vehicle stops, the catalyst’s activity is severely reduced.

The reasons for the decline in methanol catalyst activity are complex; it shows improvement over time, and approaching the end of its useful life is one such situation； The introduction of toxic substances can cause catalyst poisoning and lead to a decrease in activity; improper operation resulting in excessive temperature can also cause a decline in activity. If the activity decreases only over time as it is in use, considering raising the temperature slightly and continuing production for a while while replacing the catalyst as soon as possible might be a good option. This is because, toward the end of the catalyst’s lifespan, more by-products are generated, and continuing to use it for too long will have a negative impact on subsequent distillation processes; overall, this is not cost-effective. If the decrease in activity is caused by excessive temperature, depending on the specific circumstances, it is possible to adjust the production load for a short period of time; by increasing the hydrogen level, the catalyst can be allowed to recover slightly before resuming normal production levels. However, if the excessive temperature leads to catalyst sintering, it is better to replace the catalyst as soon as possible. If toxins are introduced, causing a decline in activity, it is recommended to address the issues of purification and refinement first; otherwise, only superficial treatments can be provided, and the root cause will not be resolved.