Applicability of “drifts” for the characterization of carbon-supported metal catalysts and carbon surfaces

Abstract

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) has been used for the first time to characterize surface groups on high surface area carbons, metal carbonyls dispersed on carbon black, and CO adsorbed on reduced carbon-supported metals. The impact of experimental parameters, such as the dilution ratio, the diluent used, the background reference chosen, and the data handling procedures, on the use of DRIFTS to characterize carbon and metal/carbon catalysts is discussed in detail. This investigation has also verified that the K-M function intensity is proportional to the concentration of IR-active species supported on carbon over a specified range of dilution ratios and carbonyl concentrations. Consequently, DRIFTS can provide a quantitative characterization technique to study carbon surface groups and IR-active species placed on carbons, and examples of carbonsupported Fe 3(CO) 12, Ru 3(CO) 12, and Os 3(CO) 12, as well as CO chemisorbed on small, carbon-supported metal particles, are provided. In addition, readily observable bands attributable to carboxyl, carboxylate, lactate, and phenol groups on treated Saran carbons demonstrate that functional groups on carbon surfaces can be identified and monitored quantitatively by the DRIFTS technique.