Suppressing Ammonia Re-Emission with the Aid of the Co3O4-NPs@KIT-6 Catalyst in Ammonia-Based Desulfurization.

The re-emission of NH3 and SO2 caused by the decomposition of (NH4)2SO3 is a crucial concern in ammonia-based desulfurization. In this study, a novel Co3O4-NPs@KIT-6 catalyst with a three-dimensional two-helix structure is proposed for converting (NH4)2SO3 into (NH4)2SO4. The oxidation rate of (NH4)2SO3 with the catalyst was 7.5 times that without any catalyst, and this improvement was attributed to appropriately dispersed Co3O4 nanoparticles with a size of 4-10 nm that interacted with the KIT-6 support. Therefore, the number of active sites with substitution and hole defects was substantially increased, which is advantageous for high catalytic activities. Consequently, the amount of NH3 and SO2 re-emission during (NH4)2SO3 oxidation was reduced by 43.9%, which considerably reduced potential environmental risks. The results of this study serve to advance ammonia desulfurization by improving the desulfurization efficiency, downsizing the oxidation tank, and generating considerable profit from efficient reclaiming of (NH4)2SO4 as a fertilizer.