An in-situ DRIFTS study of acetone adsorption mechanism on TiO2 nanoparticles

Abstract

In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigate the adsorption and catalytic reaction of acetone on TiO₂ surfaces. The adsorption of acetone has been investigated on hydrated (as-received from the provider) as well as dehydrated TiO₂ nanoparticles. On both samples, acetone shows absorption bands results from the vibrational modes of acetone adsorbed molecules. The DRIFTS spectra indicate that acetone goes into a self-condensation reaction then it dehydrated yielding mesityl oxide. Formation of formaldehyde was observed only on as received sample and it was probably activated as a result to suppress mesityl oxide formation. This suppressed formation is a result of the existence of adsorbed H₂O on the surface of as received TiO₂. Adsorbed water is not favorable for aldolization/dehydration reaction because it can block the active sites for mesityl oxide formation. Outcomes of the current study provide fundamental insight into acetone adsorption and catalytic reaction on TiO₂ nanoparticles. Specifically, this investigation demonstrates the adsorption mechanism of acetone on TiO₂ surface and the role of presenting hydroxyl group on the TiO₂ surface.

Keywords: Acetone; Adsorption; Aldolization; Mechanism; TiO(2).