Adsorption and reaction of formaldehyde on TiO 2-supported Rh catalysts studied by FTIR and mass spectrometry

Abstract

The adsorption and surface reactions of formaldehyde were studied on TiO 2 and Rh/TiO 2 catalysts at 300–473 K by Fourier-transform infrared spectroscopy (FTIR) and mass spectrometry (MS). FTIR bands due to molecularly adsorbed formaldehyde, formate, and formic acid were detected. The dominant surface species was dioxymethylene (DOM, H 2CO 2(a)) species, a part of which underwent surface polymerization resulting in polyoxymethylene (POM) on the surface. At higher temperatures molecularly adsorbed formaldehyde and DOM surface species decompose producing mainly H 2 and CO in the gas phase. The amounts of H 2 and CO were proportional with the Rh content of the catalysts. The quantity of ethylene (also formed in the above decomposition), however, changed inversely with the increase of Rh content.