Catalytically promoted combustion improves FCC (fluid catalytic cracking) operations

The advantages of a solid promoter added separately to the catalyst over the use of either a liquid promoter or a promoter incorporated into the catalyst for carbon removal during FCC catalyst regeneration include the absence of corrosion problems and flexibility regarding the amount added. Thus, the use of solid promoter with Houdry-Engelhard's HFZ-23 cracking catalyst in a unit that was previously using a large amount of recycle plus torch oil to put heat into the regenerator permitted torch oil to be discontinued, reduced recycle to the minimum needed for slurry handling, and decreased the carbon level on the recycled catalyst from 0.44 to 0.14Vertical Bar3<, thereby increasing unit conversion by 2Vertical Bar3< at a decreased catalyst-oil ratio. The catalytic combustion promoters also decrease SO/sub x/ emissions from the generator, particularly when the promoter is used with Houdry-Engelhard cracking catalysts; these tend to oxidize sulfur in the regenerator to nonvolatile compounds, possibly aluminum sulfate, which is then reduced to hydrogen sulfide in the reactor. In a test run with HFZ-20 catalyst and a solid promoter, SO/sub x/ in the regenerator flue gas dropped from 250 to 90 ppm. Other beneficial aspects of the use of solid combustion promoters with Houdry-Engelhardmore » catalysts are illustrated by industrial experiences.« less