Water–Gas Shift on Pd/α-MnO2 and Pt/α-MnO2
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Low temperature water–gas shift (WGS) catalysts, Pd nanoparticles supported on α-MnO2 nanorods termed Pd/α-MnO2 and Pt nanoparticles supported on α-MnO2 nanorods termed Pt/α-MnO2 were synthesized by introducing Pd or Pt precursor to well-prepared α-MnO2 nanorods through precipitation deposition with a following annealing at 300 °C. They are quite active for WGS in the temperature range of 140–350 °C. Activation energies for WGS on Pd/α-MnO2 and Pt/α-MnO2 are 45.3 and 56.4 kJ/mol respectively, comparable to precious metal supported on CeO2 and TiO2 for WGS. Surface chemistries of the two catalysts during WGS were tracked with ambient pressure X-ray photoelectron spectroscopy. Different from the preservation of the surface and bulk phase of other oxide support such as CeO2, TiO2 in CeO2- or TiO2-based WGS catalysts, both surface and bulk of α-MnO2 nanorods of Pd/α-MnO2 and Pt/α-MnO2 are transited to MnO during WGS. In-situ studies identified oxygen vacancies of the formed MnO support during WGS and the metallic state of Pd and Pt nanoparticles supported on the nonstoichiometric MnO.
KeywordsHeterogeneous catalysis Nanoparticles TEM Spectroscopy and General Characterisation
This work is supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy under Grant No. DE-FG02-12ER16353. We appreciate Z. Tong for help when we collected a part of the data.
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