FT-IR study on the interaction of CO2 with H2 and hydrocarbons over supported Re

The adsorption of CO2 and the co-adsorption of H2 + CO2, C1C2 alkanes + CO2 on Re supported by Al2O3, TiO2, MgO and SiO2 have been investigated by FT-IR spectroscopy. The dissociation of CO2 was not experienced on the Re/Al2O3 reduced at 673 K, it occurred, however, on the sample reduced at 1073 K. Addition of H2 to CO2, initiated the dissociation on all catalysts as indicated by CO bands at 2022-2053 cm−1. Besides, new spectral features were developed at 1600-1550, 1395 and 1365 cm−1 attributed to formate species. This assumption was confirmed by the adsorption of HCOOH vapor on these solids. No bands due to formate were detected on Re/SiO2. Adding methane and ethane to CO2 also led to the appearance of CO bands, the intensities of which were much less compared to the H2 + CO2 co-adsorption. The formation of formate also occurred to a small extent. No formate was detected following the co-adsorption of CO2-containing gas mixture on the supporting oxides alone. It was assumed that the formate species identified in the surface interactions is located on the support, where it is stabilized. The possible pathways of the occurrence of formate complex on the oxides are described.