Analysis of causes of redness of hydrocracking catalysts
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After the wax oil hydrocracking unit ran for one cycle, the catalyst was removed and regenerated. It was found that the catalyst was red and iron was suspected, but the catalyst manufacturer analyzed that the iron content did not exceed the standard. Catalytic heavy diesel has been processed during operation.
Quality Judgment of Regenerated Catalyst: 1. The particle size should be kept intact and less broken. 2. The color of the regenerated catalyst should be good. The color of the regenerated catalyst turns black, indicating that the catalyst regeneration is incomplete and the coke is not burned thoroughly enough. ； White color indicates that the regeneration temperature is too high, which may affect the performance of the catalyst. ； The color is red, indicating that the catalyst is covered with iron oxides ； If the color turns blue, it means that the packaging of the catalyst is not properly sealed after regeneration and the catalyst absorbs water. ； The catalyst is colorful, indicating uneven regeneration temperature. Catalysts with good regeneration quality are off-white in color.
It should not be a problem with iron, because the iron particles are large and will generally stick to the top of the reactor bed and will not reach the bed, so the redness is not a problem with iron. We have no experience in this area, maybe it has something to do with LCO.
This may be related to the molding of the catalyst carrier at different temperatures. When our fresh hydrogenation ultra-low sulfur catalyst is opened, a slight red color is also found.
Due to severe carbon deposits on the catalyst, the catalyst was not burned through during regeneration.
It is mentioned in the literature that excessive system temperature will cause the catalyst to turn red, but it does not explain what element or substance causes the redness.
In fact, most red colors are caused by ferrous ion compounds.
It's an iron reason. Although the iron in the raw oil does not exceed the standard, it must be present, and not only at the top of the catalyst bed, some of the iron will migrate downwards.