Synthesis and characterization of zeolites from spent FCC catalysts

Fluid catalytic cracking is one of the major secondary conversion process in petroleum refinery. Nowadays, the spent fluid catalytic cracking catalysts (FCCCs) are disposed of in landfill or stocked for a long period. Environmental risks and lack of space suggest that the management of FCCCs needs to be reviewed. The FCC catalysts contain about 3-3.5 %wt. of rare earth (RE) oxides; rare earth elements (REEs) are important for stabilization of the matrix of FCC catalysts. The main challenge is to develop an efficient process based on recovery of REEs and reuse of the solid leaching residue for some applications. In this paper a new process is proposed to recover cerium and lanthanum from FCCCs combined with reuse of the leaching solid residue for the production of synthetic zeolites. Three different zeolites were synthesized by using the solid residues from hydrochloric, nitric and sulfuric acid leaching. The chemical and physical properties of zeolites were characterized by different spectroscopic techniques including Scanning Electron Microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) for evaluating the surface morphology. The X-Ray Diffraction (XRD), the Brunauer-Emmett-Teller (BET) and Infrared Spectroscopy (FT-IR) analyses were used to characterize the structure of such zeolites. In addition, the X-ray Fluorescence (XRF) was used to identify the chemical composition. Zeolite is a solid porous material widely used as adsorbent in different processes, particularly applied to wastewater treatments. In this paper, adsorption of heavy metals onto zeolites were investigated by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES). The best results in terms of metal removal were achieved by the zeolite synthesized from the sulfuric acid leaching residue.