A kinetic study of Hg(0) oxidation over Mo-promoted V-based SCR catalyst

A kinetic study of elemental mercury (Hg(0)) oxidation reaction over molybdenum (Mo)-promoted vanadium (V)-based selective catalytic reduction (SCR) catalyst was carried out. To probe the role of HCl and O-2 in Hg(0) oxidation over the catalyst, a real-time Hg(0) oxidation experiment was conducted. It was found that Hg(0) adsorption was negligible and HCl adsorbed onto the catalyst surface could show consistent Hg(0) oxidation performances in the presence of O-2 at realistic SCR temperatures. NH3 showed competitive adsorption with HCl, resulting in degrading Hg(0) oxidation performance. X-ray Absorption Near-Edge Structure (XANES) data for mercury species showed that HgCl2 was the major mercury species formed onto the spent catalyst under typical flue gas conditions. Based on the current and previous studies, an Eley-Rideal followed by Langmuir-Hinshelwood mechanism was proposed, comprising multiple elementary reaction steps. A steady-state kinetic study was conducted based on an assumption of HgCl formation as a rate-determining step. The kinetic and thermodynamic parameters determined from this study shed light on fundamental insights and practical catalytic reactor designs.

Automated summary

In this study, the impact of HCl and NH3 on Hg(0) oxidation catalytic reaction was investigated through real-time Hg(0) oxidation experiment and X-ray Absorption Near-Edge Structure analysis. The research revealed that Hg(0) oxidation is influenced by the combined action of HCl and O-2. HgCl2 was identified as the major mercury species formed on the spent catalyst under typical flue gas conditions.