Characterization of a CO/H2 reaction intermediate by FT-IRAS: potassium formate on Ru(001)

In-situ Fourier Transform-Infrared Reflection Absorption Spectroscopy (FT-IRAS) FT-IRAS has been utilized to characterize a reaction intermediate observed during CO hydrogenation at high pressures over potassium promoted Ru(001). This intermediate is identified as a potassium formate by vibradonal spectra obtained under reaction conditions. Vibrational spectra of formate obtained from the decomposition of formic acid on clean Ru(001) and K-Ru(001) allow us to further characterize this intermediate with respect to its symmetry, configuration and K-OOCH bond formation. The presence of potassium thermally stabilizes the formate on the surface in comparison to clean Ru(001). The observation of such a formate intermediate is an important step in elucidating the role of alkali promoters for the synthesis of oxygenates in the CO hydrogenation in catalysis where they have been proposed to be active intermediates.