IN-SITU FTIR STUDY ON HYDROGENATION OF CARBON-DIOXIDE OVER TITANIA-SUPPORTED COPPER-CATALYSTS

The effects of co-catalyst were studied on the methanol-synthesis reac tion from carbon dioxide and hydrogen over various TiO2-supported copp er catalysts. The catalytic activities with a continuous flow reactor were measured together with in situ infrared spectra at the elevated t emperature and pressure. Phosphorus did not show any activity. Potassi um showed a high activity but promoted CO formation. ZnO had a high ac tivity and a high methanol selectivity. ZrO2 also showed promotion eff ect to some extent. By in situ Fourier transform infrared spectroscopy (FTIR), the formate species formed on Cu was observed over CuO/TiO2 c atalyst. The amount of the formate species depended on the kinds of ad ditive. Addition of K, Zr and Zn showed high activity and increased th e intensities of the formate species. On the other hand, addition of P decreased the activity and the intensities of the formate species. Am ong them, Zn addition increased the amount of adsorbed formate species markedly and obtained the highest methanol yield. (C) 1998 Elsevier S cience B.V.