Suppressing Ammonia Re-Emission with the Aid of the Co 3 O 4 -NPs@KIT-6 Catalyst in Ammonia-Based Desulfurization

The re-emission of NH 3 and SO 2 caused by the decomposition of (NH 4 ) 2 SO 3 is a crucial concern in ammonia-based desulfurization. In this study, a novel Co 3 O 4 -NPs@KIT-6 catalyst with a three-dimensional two-helix structure is proposed for converting (NH 4 ) 2 SO 3 into (NH 4 ) 2 SO 4 . The oxidation rate of (NH 4 ) 2 SO 3 with the catalyst was 7.5 times that without any catalyst, and this improvement was attributed to appropriately dispersed Co 3 O 4 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 NH 3 and SO 2 re-emission during (NH 4 ) 2 SO 3 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 (NH 4 ) 2 SO 4 as a fertilizer.