Mn/Mg/Al-spinels as catalysts for SOx abatement: Influence of CeO2 incorporation and catalytic stability

Mg,Mn,Al-oxides with spinel structure, Al/(M2+ + Al) molar ratio of 0.25 and 0.50 and an Mn/Mg molar ratio of 0.30 have been evaluated as catalysts for SOx removal under conditions similar to those found in FCC units. The best performance was that of the sample with the higher aluminium content. The incorporation of CeO2 in this sample favored SOx uptake for short reaction times as well as the reduction of the sulfated catalysts. When the regeneration was started at 530 °C, only H2S was observed as reaction product, but when this step started at 650 °C, the release of SO2 preceded that of H2S, regardless of the chemical composition of the sample. As to the additive performance for successive reaction–regeneration cycles, the incorporation of CeO2 produced a less efficient catalyst with regard to the removal of the SO2 along the process, but with a higher regeneration efficiency and a lower formation of SO2 as regeneration product.