Facilitating calcium sulfite oxidation during flue-gas desulfurization for efficient sulfur utilization using a robust MnTiO3 perovskite

Accelerating the oxidation of calcium sulfite is extremely crucial for the limestone/gypsum method of flue-gas desulfurization by enhancing the desulfurization efficiency, preventing subsequent SO 2 release, and generating pure calcium sulfate as a value-added product for downstream utilization. In this work, MnTiO 3 perovskite nanodisks with high crystallinity and good thermal stability were synthesized by a hydrothermal method. The highly stabled exposed 001 facets of the MnTiO 3 catalyst give rise to its catalytic reactivity which promote the electron transfer in sulfite oxidation process thus effectively generated reactive oxygen species ( O 2 − , OH, and SO 4 − ) to accelerate the sulfite oxidation cycle. Compared with non-catalytic oxidation reactions, the calcium sulfite oxidation rate and calcium sulfate yield were increased by 4.3 times and 34.02% by using MnTiO 3 , respectively. After four cycles, the calcium sulfite oxidation rate was only 9.57% lower than that in the first cycle, and Mn leaching was minimal. To simulate actual usage scenarios, the extrusion method was employed to prepare a molded catalyst for facile separation from the desulfurization slurry, which revealed acceptable performance at a dosage of 10 g·L −1 . The proposed MnTiO 3 perovskite catalyst is non-toxic, cost-effective, convenient to synthesize, and recyclable, providing new possibilities for sulfur reclamation during flue-gas desulfurization.