Is catalyst carbon deposits the cause of deactivation of the reforming catalyst?

When the surface of the reforming catalyst is slightly carbonized, because of the carbon covering the active centre, the activity decreases and the heat absorption decreases, and there are spots, hot strip, and the aromatics in the exit tail gas increase; when the catalyst is seriously carbonized, it shows that the bed resistance increases rapidly, and the reforming furnace tube surface temperature rises quickly until there is a red tube. The causes of catalyst carbon build-up are generally as follows:

1) Raw material: the index of hydrocarbon raw material exceeds the standard, aromatics are too high, olefins are too high, specific gravity is too large, and sulfur content, chlorine content and other poisons exceed the standard, resulting in catalyst poisoning.

2) Water-carbon ratio imbalance. Feed fluctuations, temperature, pressure fluctuations lead to water-carbon ratio reduced to below normal value, the water-carbon ratio to a certain extent will lead to carbon accumulation in the conversion process.

3) Uneven combustion of the converter nozzle, resulting in one-sided heating of the furnace tube or local high temperature will also cause different degrees of carbon formation on the conversion catalyst.

4) Repeated oxidation and reduction of the catalyst during repeated start-up and shutdown will lead to a decrease in catalyst activity, which in turn will lead to carbon deposits on the catalyst.

5) The catalyst is not effectively protected because the feed material is not removed in time during the emergency stoppage.

6) Insufficient catalyst reduction leads to poor catalyst activity in the upper part of the plant, causing heavy hydrocarbons to penetrate into the lower high temperature bed and cause carbon accumulation in thermal cracking.