Reaction of Formic Acid over Amorphous Manganese Oxide Catalytic Systems: An In Situ Study

Abstract

The interaction of formic acid with amorphous manganese oxide (AMO) is investigated using in situ photoelectron and infrared spectroscopy techniques. Soft X-ray photoelectron spectroscopy (sXPS) and in situ FTIR illustrate two possible modes of formate bound species at the AMO surface. Two peaks in the IR region from 1340−1390 cm −1 are indicative of formate species bound to the surface in a bidentate configuration. However, a 224 cm −1 band gap between ν s OCO and ν as OCO suggests formate is bound in a bridging configuration. Temperature-programmed desorption studies confirm the formate bound species desorbs as carbon dioxide from the surface at multiple binding sites. At temperatures above 700 K, the presence of K + ···OC complex suggests the bound species interacts at vacant sites related to framework oxygen and cation mobility.