EXAFS and FT-IR Characterization of Mn and Li Promoted Titania-Supported Rh Catalysts for CO Hydrogenation
The effect of Li and Mn promoters on the structure and selectivity of supported Rh catalysts for CO hydrogenation reaction was examined. Infrared spectroscopy and X-ray absorption were used to investigate the adsorption of reactants and local structure of Rh. These techniques were used in combination with reactivity, H{sub 2} chemisorption, and temperature programmed studies to correlate structural characteristics with activity and selectivity during CO hydrogenation of unpromoted Rh/TiO{sub 2} and three promoted Rh catalysts: Rh-Li/TiO{sub 2}, Rh-Mn/TiO{sub 2}, and Rh-Li-Mn/TiO{sub 2}. The presence of a promoter slightly decreases the Rh clusters size; however, no evidence for an electronic effect induced by the presence of Li and Mn was found. Higher turnover frequencies were found for the promoted catalysts, which also showed the lower dispersion. The Li promoter introduces a weakened CO adsorption site that appears to enhance the selectivity to C{sub 2+} oxygenates. The selectivity to C{sub 2+} oxygenates varies inversely with the reducibility of Rh metal, that is, the lower the Rh reducibility, the higher the selectivity.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1042330
- Report Number(s):
- BNL-98008-2012-JA; TRN: US201212%%740
- Journal Information:
- ACS Catalysis, Vol. 1, Issue 10; ISSN 2155-5435
- Country of Publication:
- United States
- Language:
- English
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