Catalytic Oxidation Of Elemental Mercury With The Thermal-Decomposition Of CuBr₂and A Membrane Delivery Setup

Mercury existed in the environment characterized as high volatile andpersistent pollutant. It accumulated in the body of creatures in the form ofmethyl mercury and brought a profound impact on nervous system. Therewere three states in flue gas: Hg2+, Hg0and HgP. Among them, Hg2+and HgPcould be eliminated with current air pollution controlling device (APCD).However, due to its high volatility and low solubility, Hg0was difficult to beeliminated. One feasible measurement was that Hg0oxidized to Hg2+withcatalysts. Nowadays many catalysts have been developed. But due to tracelevel of Hg0concentration, excessive oxidant like HCl was added to meet theelimination requirement. Excessive HCl caused duct corrosion as well assecondary pollution.The current research employed controlled-release catalysis membranesystem to achieve the conversion from Hg0to Hg2+. In addition, we designeda device that can combine the reaction reactor with the mercury detection as a whole, to avoid the data errors resulted from the adsorbed Br on thedownstream pipe which caused the wall effect on the outlet mercurymeasurement. Thus more reliable experimental data could be obtained. Thestudy showed that the data from the reaction and detection integration devicedisplayed high credibility.According to Co, V, Cu, Mn, Zr catalysis membrane, Hg0oxidationefficiency was the utmost with MnOx catalysis membrane, and Br performedmuch better than Cl.80%Hg0could be eliminated at200℃and75mgAl2O3. However, SO2in flue gas seemed to influence Hg0oxidationobviously while NO showed slight promotion.Addtionally, by adding Zr into Mn catalysis membrane, Mn-Zr systemperformed better Hg0oxidation and anti-SO2ability. Moreover, Mn-Zrcatalysis membrane had a wide temperature window which was from200℃to300℃.Meanwhile, XRD, H2-TPR and XPS were employed to test catalysismembrane. In the MnOx-ZrOx/α-Al2O3catalysis membrane system, MnOxexisted mainly in the form of MnO02. SO2and Hgcompetitively adsorbed onthe active sites, thus SO2could transform into sulfate. ZrOx was inertia. Therole of Zr focused on promoting dispersion of MnOx and increasing theactive sites. Besides, it was helpful for improving SO2resistance. The reaction between Hg0and HBr obeyed the process of Deacon reaction whilethe reaction between Hg0and Br2was direct oxidation reaction. Theadsorption of Hg0and HBr could be explained by Mars-Maessen mechanismand Langmuir-Hinshelwood mechanism probably was the reason ofadsorption of Hg0and Br2.