Comparative study of CO adsorption on zirconia polymorphs with DRIFT and transmission FT-IR spectroscopy

The interactions of CO with amorphous, monoclinic, and tetragonal zirconia were investigated by diffuse reflectance infrared (DRIFT) and transmission FT-IR spectroscopy to determine the active sites for CO adsorption. The results showed that zirconia polymorphs exerted a great influence on CO bands and the formation of surface intermediates. Meanwhile, differences of CO bands and surface intermediates were observed between DRIFT and transmission FT-IR spectra. Two ways were proposed to produce active sites for CO adsorption, one way was thermal dehydroxylation in vacuum and the other was CO reaction with hydroxyls at high temperature. The former was the main way to produce active sites for CO adsorption in transmission FT-IR spectra, and the latter was the main way to produce active sites for CO adsorption in DRIFT spectra.