Kinetics of Co oxidation over unloaded and pd-loaded α-Fe2 O3 spherical submicron powder catalysts: Photoacoustic investigations at low pressure

Joong Seok Roh, Ji Yeong Kim, Joong Gill Choi, Sung Han Lee

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Abstract

In this study, α-Fe2 O3 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-Fe2 O3 spherical particles and 14 wt % Pd/α-Fe2 O3 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-Fe2 O3 submicron powder and 13.2 kcal/mol for the 14 wt % Pd/α-Fe2 O3 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-Fe2 O3 submicron powder, while 0.48 order to Po2 was observed for CO oxidation over Pd/α-Fe2 O3 submicron powder. The partial orders with respect to PCO were determined as 0.58 and 0.54 for the α-Fe2 O3, and the Pd/α-Fe2 O3 submicron powders, respectively. The kinetic results obtained from both catalysts were compared with those for the α-Fe2 O3 fine powder catalysts and were used to understand the reaction mechanism.

Original languageEnglish
Article number98
JournalCatalysts
Volume8
Issue number3
DOIs
Publication statusPublished - 2018 Mar

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All Science Journal Classification (ASJC) codes

  • Catalysis
  • Physical and Theoretical Chemistry

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