Treatment of fluid catalytic cracking spent catalysts to recover lanthanum and cerium: Comparison between selective precipitation and solvent extraction

• Treatment of FCC spent catalysts.
• Hydrometallurgical route to recover lanthanum and cerium from FCC spent catalysts.
• Selective precipitation of rare earths from leach liquor.
• Solvent extraction of rare earths, stripping and calcination.

The paper is focused on the study of hydrometallurgical processes for recovery of rare earths (RE) from fluid catalytic cracking catalysts (FCCC). According to the experimental results two processes were proposed: in the first one RE were recovered as double sulfates by selective precipitation with sodium hydroxide after leaching with sulfuric acid. The second approach consisted of dissolution of powder by acids, solvent extraction by (2-ethylhexyl)phosphoric acid (D2EHPA), stripping and precipitation of RE oxalates using oxalic acid.Experiments showed that solvent extraction was found to be beneficial in terms of achieving improved final products quality with greater purity (∼98%).