Effect of Calcination Temperature on the Characterization of Spent Catalyst

Disposal of spent catalyst is a growing concern for all refiners. Environmental regulations are becoming increasingly stricter and there are state recommendations to develop disposal routes that emphasize recycling as much as possible and processing the wastes as near as possible. In this context, a recycling process has been carried out for the Ni-Mo/Al2O3 spent catalyst used in oil refineries. The process starts with a deoiling of the catalyst to eliminate oil and then calcination at different temperatures to remove carbon-contaminated. Fresh and spent catalyst samples were analyzed by a variety of techniques, which include X-ray diffraction (XRD), infrared spectroscopy (IR), crushing strength, bulk crushing strength, surface area, and pore volume. The activities of fresh and spent catalysts have been studied using micropulse techniques and cyclohexene as a model molecule. It has been noticed that, after the regeneration step, there was some nickel promoter loss due to nickel spinel (NiAl2O4) formation. The spinel formation explains why the catalytic activity of the fresh catalyst was not fully recovered after the regeneration of the spent catalyst.