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Title: Synthesis Gas Conversion over Rh-Based Catalysts Promoted by Fe and Mn

Rh/SiO2 catalysts promoted with Fe and Mn are selective for synthesis gas conversion to oxygenates and light hydrocarbons at 523 K and 580 psi. Selective anchoring of Fe and Mn species on Rh nanoparticles was achieved by controlled surface reactions and was evidenced by ultraviolet–visible absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The interaction between Rh and Fe promotes the selective production of ethanol through hydrogenation of acetaldehyde and enhances the selectivity toward C2 oxygenates, which include ethanol and acetaldehyde. The interaction between Rh and Mn increases the overall reaction rate and the selectivity toward C2+ hydrocarbons. The combination of Fe and Mn on Rh/SiO2 results in trimetallic Rh-Fe-Mn catalysts that surpass the performance of their bimetallic counterparts. The highest selectivities toward ethanol (36.9%) and C2 oxygenates (39.6%) were achieved over the Rh-Fe-Mn ternary system with a molar ratio of 1:0.15:0.10, as opposed to the selectivities obtained over Rh/SiO2, which were 3.5% and 20.4%, respectively. The production of value-added oxygenates and C2+ hydrocarbons over this trimetallic catalyst accounted for 55% of the total products. X-ray photoelectron spectroscopy measurements suggest that significant fractions of the Fe and Mn species exist as metallic iron and manganesemore » oxides on the Rh surface upon reduction. These findings are rationalized by density functional theory (DFT) calculations, which reveal that the exact state of metals on the surfaces is condition-dependent, with Mn present as Mn(I) and Mn(II) oxide on the Rh (211) step edges and Fe present as Fe(I) oxide on the step edge and metallic subsurface iron on both Rh steps and terraces. CO Fourier transform infrared spectroscopy and DFT calculations suggest that the binding of CO to Rh (211) step edges modified by Fe and/or manganese oxide is altered in comparison to CO adsorption on a clean Rh (211) surface. These results suggest that Mn2Ox species and Fe and Fe2O modify bonding at Rh step edges and shift reaction selectivity away from CH4.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [3] ;  [1] ; ORCiD logo [1] ; ORCiD logo [4]
  1. Department of Chemical and Biological Engineering, University of Wisconsin—Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
  2. Department of Chemical and Biological Engineering, University of Wisconsin—Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States; Institute of Chemistry, University of Campinas (UNICAMP), P.O. Box 6154, 13083-970 Campinas, São Paulo, Brazil
  3. Institute of Chemistry, University of Campinas (UNICAMP), P.O. Box 6154, 13083-970 Campinas, São Paulo, Brazil
  4. Department of Chemical and Biological Engineering, University of Wisconsin—Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, United States
Publication Date:
Grant/Contract Number:
EE0006878; SC0014058; FG02-05ER15731; AC02-06CH11357; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 7; Journal Issue: 7; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Wisconsin Materials Research Science and Engineering Center; Environmental Molecular Sciences Laboratory (EMSL); the Center for Nanoscale Materials (CNM) at Argonne National Laboratory; and the National Energy Research Scientific Computing Center (NERSC); Center for Nanoscale Materials (CNM) at Argonne National Laboratory; National Energy Research Scientific Computing Center (NERSC)
Country of Publication:
United States
Language:
English
Subject:
ethanol; iron; manganese; oxygenates; rhodium; synthesis gas; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1396167
Alternate Identifier(s):
OSTI ID: 1396009