FTIR study of adsorption and photochemistry of amide on powdered TiO2: Comparison of benzamide with acetamide

FTIR has been used in situ to investigate the adsorption, thermal transformation, and photoreactions of benzamide on TiO2. The reaction pathways are compared to the case of acetamide. Our reaction system is focused on the vapor–solid surface reactions, which are complementary to the reactions catalyzed in the solution phase. Benzamide is adsorbed molecularly or dissociatively to generate C6H5CONH by losing one amino hydrogen at 35 °C. Upon raising the TiO2 surface temperature, C6H5CN and C6H5COO are produced. Under photoirradiation in O2, adsorbed benzamide and C6H5CONH are transformed into surface species of NCO, C6H5COO, and C6H5CN and gaseous CO2, revealing versatile photoreaction pathways. These surface intermediates were not found in a previous study of benzamide photodecomposition catalyzed by TiO2 in the solution phase. Similar reaction pathways were found for acetamide on TiO2. It is worthy of note that –CONH2 on TiO2 is transformed into –CN thermally and photochemically. –CN reacts reversibly with surface OH groups to form –CONH2.