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Open AccessArticle

Kinetics of CO Oxidation over Unloaded and Pd-Loaded α-Fe2O3 Spherical Submicron Powder Catalysts: Photoacoustic Investigations at Low Pressure

1
Department of Chemistry, Yonsei University, Seoul 03722, Korea
2
Department of Chemistry, Yonsei University, Wonju 26493, Korea
*
Authors to whom correspondence should be addressed.
Catalysts 2018, 8(3), 98; https://doi.org/10.3390/catal8030098
Received: 29 January 2018 / Revised: 23 February 2018 / Accepted: 24 February 2018 / Published: 28 February 2018
(This article belongs to the Special Issue Conversion of CO2 into CO Using Heterogeneous Catalysis)
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Abstract

In this study, α-Fe2O3 spherical particles with an average diameter of approximately 200 nm were synthesized by a solvothermal method for use as both a catalyst and medium for a Pd catalyst. The kinetics of CO oxidation over powders of α-Fe2O3 spherical particles and 14 wt % Pd/α-Fe2O3 spherical particles were measured in a static reactor by using a CO2 laser-based photoacoustic technique. The total pressure was fixed at 40 Torr for the CO/O2/N2 mixture for temperatures in the range of 225–350 °C. The variation in the CO2 photoacoustic signal with the CO2 concentration during CO oxidation was recorded as a function of time, and the CO2 photoacoustic data at the early reaction stage was used to estimate the rates of CO2 formation. Based on plots of ln(rate) vs. 1/T, apparent activation energies were calculated as 13.4 kcal/mol for the α-Fe2O3 submicron powder and 13.2 kcal/mol for the 14 wt % Pd/α-Fe2O3 submicron powder. Reaction orders with respect to CO and O2 were determined from the rates measured at various partial pressures of CO and O2 at 350 °C. The zero-order of the reaction with respect to Po2 was observed for CO oxidation over α-Fe2O3 submicron powder, while 0.48 order to Po2 was observed for CO oxidation over Pd/α-Fe2O3 submicron powder. The partial orders with respect to PCO were determined as 0.58 and 0.54 for the α-Fe2O3, and the Pd/α-Fe2O3 submicron powders, respectively. The kinetic results obtained from both catalysts were compared with those for the α-Fe2O3 fine powder catalysts and were used to understand the reaction mechanism. View Full-Text
Keywords: photoacoustic technique; kinetics of CO oxidation; α-Fe2O3 spherical powder catalyst; Pd/α-Fe2O3 catalyst photoacoustic technique; kinetics of CO oxidation; α-Fe2O3 spherical powder catalyst; Pd/α-Fe2O3 catalyst
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Roh, J.-S.; Kim, J.-Y.; Choi, J.-G.; Lee, S.-H. Kinetics of CO Oxidation over Unloaded and Pd-Loaded α-Fe2O3 Spherical Submicron Powder Catalysts: Photoacoustic Investigations at Low Pressure. Catalysts 2018, 8, 98.

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