Catalyst deactivation
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Has anyone seen catalyst deactivation occur? What are the specific symptoms, and how is it addressed? It would be good to have information on the timing related to this
There are three types of catalyst deactivation: 1. Coking deactivation, which is the most severe and rapid form of deactivation; it can cause the catalyst to lose most of its activity within just 1 second. However, this type of deactivation is temporary and the catalyst can regain its functionality after regeneration. 2. Hydrothermal deactivation: During use, the catalyst is repeatedly exposed to high temperatures and water vapor, which causes changes in its surface structure, a reduction in specific surface area and pore volume, and damage to the crystal structure of the molecular sieve. This leads to a decline in the catalyst’s activity and selectivity, and once this deactivation occurs, it is irreversible. 3. Poisoning and deactivation: Crude oil, especially heavy crude oils, often contains certain heavy metals such as iron, nickel, copper, vanadium, calcium, etc. These metals can poison or contaminate the catalyst, resulting in a decrease in its activity. The deactivation phenomenon is evident: even by increasing the inlet temperature of the synthesis tower to 240–260, the synthesis conversion rate remains very low ； The heat of synthesis reaction cannot maintain the bed temperature ； Production fails to meet targets, etc.
It has been encountered that poisoning leads to inactivation; the hydrogenation efficiency decreases, and even after increasing the reaction temperature, the quality of the product remains unsatisfactory
{:3_57:} Great!
The main approach is to increase the reaction temperature; however, the product quality does not improve, and there is also some coking phenomenon, which can be observed through the pressure difference. There is also the radial temperature difference, though this difference could also be due to the collapse of the catalyst bed.