In-situ plasma regeneration of deactivated Au/TiO2 nanocatalysts during CO oxidation and effect of N2 content

Abstract

Driven by excellent CO oxidation capability of gold nanocatalysts at room temperature, a TiO2 supported Au nanocatalyst (Au/TiO2) was synthesized by deposition–precipitation method. To solve the deactivation issue of Au/TiO2 catalyst during CO oxidation, in-situ regeneration by N2/O2 plasma was employed. Pure O2 plasma could reversibly regenerate the deactivated Au/TiO2 catalyst, however, N2 addition resulted in an extra catalyst poisoning during regeneration. The extra poisoning effect was the most severe at 10% N2 and became much weaker at 80% N2. To investigate the formation of any surface poisoning species [NOy]s on Au/TiO2 catalyst, gaseous product of N2/O2 plasma over fresh Au/TiO2 catalyst was on-line analyzed by FT-IR, followed by catalyst characterization with temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The Au/TiO2 catalysts before and after plasma regeneration were also measured by transmission electron microscopy (TEM), in order to exclude the poisoning effect arisen from the change in gold particle size or morphology.