Surface Chemistry and Morphology of Zirconia Polymorphs and the Influence on Sulfur Dioxide Removal

Zirconium hydroxide was calcined at discrete temperatures up to 900 degrees C to study the effect of thermal treatment on the structure and surface chemistry related to the filtration of SO2. As-received and calcined materials were characterized using multiple techniques that included thermal gravimetric analysis, X-ray diffraction, and nitrogen porosity to determine changes to the zirconium hydroxide structure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy were used to characterize changes in surface hydroxyl groups. Changes in the morphology and surface chemistry were correlated to sulfur dioxide filtration through chemical breakthrough studies. It was found that as calcination temperature increased, materials become more crystalline, which led to the loss of terminal hydroxyl groups and a decrease in the efficacy for sulfur dioxide removal.