Abstract: A method for removing gas contaminants from flowing solids in a fluid catalytic cracking (FCC) process can include: catalytically cracking a hydrocarbon feedstock in the presence of a catalyst in a riser of a FCC unit to produce a hydrocarbon product; separating the hydrocarbon product from a spent catalyst to produce a hydrocarbon product stream; regenerating the spent catalyst in a regeneration gas comprising oxygen to produce a mixture comprising a regenerated catalyst and a gas contaminant at a first concentration; introducing a stripping gas and the mixture into a regenerated catalyst stripper to produce a regenerated catalyst stream comprising the regenerated catalyst, the stripping gas, and a gas contaminant at a second concentration that is reduced by 50% or greater as compared to the first concentration; and introducing the regenerated catalyst stream to the riser.