The low-temperature interaction between H2 + CO2 on Rh/Al2O3 was investigated by adsorption and infrared spectroscopic measurements. Adsorption studies indicated that the presence of H2 greatly enhances the uptake of CO2 by Rh/Al2O3 catalyst. Infrared spectroscopic studies revealed that adsorbed formate and CO are formed in the low-temperature interaction between H2 and CO2. On comparison of the spectrum of adsorbed CO with that obtained after coadsorption of the H2 + CO2 mixture, it appeared that (i) the doublet due to twin CO (Rh/CO2) was completely missing, (ii) the linearly bonded CO appeared at lower frequency, 2020–2039 cm−1, and (iii) no significant change was observed in the position of the bridged CO. The apparent activation energy of the formation of formate ion was calculated to be 4.2 kcal/mol, which is markedly lower than that determined for pure Al2O3, indicating the great promoting effect of Rh. Possible mechanisms of the H2 + CO2 interaction are discussed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry