The evolution of carbon (C) and nitrogen (N) in a spent (coked) fluid catalytic cracking (FCC) catalyst was investigated during regeneration. A commercial spent FCC catalyst from one refinery was submitted to calcination procedures with air, and samples were collected at different temperatures and times. These were analyzed by X-ray photoelectron spectroscopy (XPS) before and after milling to follow the variation of C and N contents in the surface. It was observed that both C and N are preferably located on the external FCC catalyst surface. For a total C amount of 1.3 wt %, the C content on the surface is about 18.3 wt %. The surface N present in coke is 1.4 wt %, so that the calculated amount of N in the spent catalyst is 176 ppmw. During thermal treatments a simultaneous removal of C and N from the spent catalyst was observed. However, N evolution was slightly slower and completed at a higher temperature than C.

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Herein, a sol-gel one-pot methodology to tune the activity of Co-catalysts supported on silica-titania to CO oxidation is described. SEM, TEM, EDS, XPS and H 2-TPR evidenced a higher Co dispersion from that method when compared to catalysts prepared by impregnation. Furthermore, the simultaneous addition of cobalt oxalate during the incorporation by sol-gel of a controlled low Ti amount into the silica (Si/Ti = 5.7) was determinant to improve the Co dispersion and to avoid the formation of Co-species with strong support interaction. Moreover, XPS analyses evidenced that the mentioned low Ti amount favoured a higher formation of superficial Co 3+ and lattice O 2− species, which promoted a higher CO oxidation specific activity and, more importantly, strongly decreasing the light-off temperature. On the other hand, Rietveld analyses, Raman spectroscopy, H 2-TPR and XPS data showed that the incorporation of higher amounts of Ti into the silica (Si/Ti = 0.2) led to the formation of cobalt titanate, decreasing the concentration of superficial Co 3+ and lattice O 2− species and, consequently, decreasing the specific activity toCO oxidation.

The relative importance of possible factors leading to the deactivation of a commercial SO x emission reduction additive used in the fluid cracking process was evaluated individually. This additive was based on mixed oxides of Mg and Al and contained small amounts of Ce and V. The laboratory deactivation simulation was an extended hydrothermal treatment of the additive by steam with or without the presence of sources of possible poisons such as Si, V, and S. It was observed that a reduction of the area and sintering and migration of V from the catalyst to the additive did not affect the performance of the additive. However, migration of Si from a fresh catalyst or sulfate from an impregnated catalyst drastically reduced the SO x adsorption capacity of the additives. As the migration of Si was important mainly with fresh catalyst, which is present in the inventory of the unit in very small quantity compared to the large amount of equilibrium catalyst, the main factor leading to deactivation of the SO x additives in the industrial operation can be attributed to formation of stable sulfates.