In situ Fourier-transform infrared study of CO–H ₂ reactions over Rh/Al ₂ O ₃ catalysts at high pressure and temperature

Infrared spectra are reported of methanol and ethanol adsorbed on Rh/Al2O3 at 473 K, and of the adsorbed products of the reaction of CO(1 MPa)–H2(2MPa) over alumina and Rh/Al2O3 at 553 K. Catalysis by rhodium leads to production of methanol and ethanol over Rh/SiO2, but the alcohols interact further with the alumina support in Rh/Al2O3 to give surface methanoate and ethanoate anions. Methanoate species are also formed from CO–H2 over alumina alone in the absence of rhodium. Rh/Al2O3 showed a higher selectivity towards methane than Rh/SiO2 possibly via the involvement of methanoate as an intermediate species.