Interaction of formic acid with Fe2O3 powders under different atmospheres:: an XPS and FTIR study

The interaction between haematite powder and formic acid has been studied at atmospheric pressure by FTIR and under high-vacuum conditions by X-ray photoelectron spectroscopy (XPS) and mass spectroscopy (MS). At room temperature formic acid is adsorbed mainly molecularly whereas dissociative chemisorption is prevalent at higher temperatures. Heating to >500 K causes decomposition of the formate with the formation of carbon monoxide, carbon dioxide, hydrogen and water. Suggestions are made concerning the surface acid sites in connection with the chemisorption and the reaction pathway. The results obtained are compared with those previously achieved by the chemisorption of methanol on iron oxide.