화학공학소재연구정보센터
Catalysis Today, Vol.263, 75-83, 2016
Evaluation of Rh/CexTi1-xO2 catalysts for synthesis of oxygenates from syngas using XPS and TPR techniques
Rh/CexTi1-xO2 catalysts have been investigated for the synthesis of ethanol from syngas. For this purpose various CexTi1-xO2 (x=0, 0.25, 0.5, 0.75, and 1) solid solution supports were synthesized using co precipitation, which is an inexpensive and environmental friendly method. 2 wt% Rh has been deposited over these supports by using wet impregnation method. We have evaluated these Rh catalysts for synthesis of ethanol from syngas at atmospheric pressure and 350 psi. Among, the various catalysts, Rh supported on Ce0.75Ti0.25O2 catalyst exhibit better selectivity toward oxygenates compared to other catalysts. Interestingly, Ti rich samples exhibit higher selectivity toward hydrocarbons while Ce rich samples exhibit higher selectivity toward oxygenated products. The catalytic results at atmospheric pressure show that titania rich catalysts exhibit higher H-2 conversion and ceria rich catalysts exhibit higher CO-conversion at 250 degrees C at atmospheric pressure. Temperature programmed reduction measurements suggest that Rh promotes the cerium surface reduction. X-ray photoelectron measurements show that all the catalysts exhibit peaks due to Ce4+ and Ce3+ oxidations states in the Ce 3d spectra. Ols spectra of activated Rh/TiO2 and Rh/Ce0.5Ti0.5O2 catalysts show two peaks after reduction in hydrogen. One peak is due to the oxygen atoms from the individual oxides and the other peak is from the compound formation between Rh and the support. X-ray photoelectron measurements of activated catalysts also show that Rh/Ce0.5Ti0.5O2 catalyst exhibit higher Rh1+ ions on the surface compared to Rh/TiO2 and exhibits better selectivity toward oxygenated products. (C) 2015 Elsevier B.V. All rights reserved.