Catalytic conversion of mercury over Ce doped Mn/SAPO-34 catalyst: Sulphur tolerance and SO/SO conversion.

A series of Mn-Ce/SAPO-34 catalysts were prepared to study the catalytic oxidisation of elemental mercury (Hg). Sulphur tolerance and SO formation over the catalyst were studied further. Hg was transported by compressed air from PSA Cavkit. NO, SO, and NH are standard gases, and HO is produced by gas carrying. Mn could incorporate into the cerium oxide lattice to form capping oxygen and well-dispersed high valance manganese ions after the addition of Ce, which was conducive to NO removal and Hg oxidisation. 9 Mn-9Ce showed the best performance regarding Hg conversion, achieving more than 92% Hg conversion efficiency at 50-300 °C. The sulphur resistance of the Mn-based catalyst was significantly improved after the addition of cerium due to the high affinity of Ce for SO, and the relative content of HgSO was exceeded 72% on the 9 Mn-9Ce catalyst with SO; SO formation over the 9 Mn-9Ce decreased by 17% compared with the 9 Mn. HO not only reduced the available active site, but also decreased the oxidation rate of SO. The active sites were preferentially occupied by NH rather than Hg and SO, generated NH occupied cation vacancies. Therefore, both HO and NH have inhibitory effects on Hg conversion and SO formation.