The interaction of oxygen with high loaded Ru/{gamma}-Al{sub 2}O{sub 3} catalyst

Journal Article · Wed Feb 04 04:00:00 EST 2009 · Materials Research Bulletin

DOI:https://doi.org/10.1016/j.materresbull.2008.05.018· OSTI ID:21199669

Okal, Janina ^[1]

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1. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)

The interaction of oxygen with the Ru/{gamma}-Al{sub 2}O{sub 3} catalyst comprising metal particle with sizes of 1-16 nm, was examined over a temperature range 20-400 deg. C. The catalyst loaded with 10.8 wt.% Ru was prepared by incipient wetness from RuCl{sub 3} precursor. The structure of the Cl-containing catalyst and the catalyst after elimination Cl{sup -} ions was characterized using H{sub 2} and O{sub 2} chemisorption, O{sub 2} uptake, BET, XRD and TEM. The Cl{sup -} ions in the catalyst decreased the H{sub 2} and O{sub 2} chemisorption capacity of Ru and caused large discrepancies between the mean particle size calculated from gas chemisorption and from TEM. Exposure to O{sub 2} at 100-200 deg. C caused oxidation of small Ru particles, while larger particles were covered with very thin Ru{sub x}O{sub y} skin (undetected by XRD and TEM). The O/Ru ratio increased up to 200 deg. C implying high affinity of the small Ru particles to oxygen. Oxidation at 250 deg. C led to the formation of poorly crystalline RuO{sub 2} particles with a mean size of 4 nm, and coverage of large Ru particles with 1.6 nm thick oxide layer. At 300 and 400 deg. C crystallization of the RuO{sub 2} phase, as well as significant agglomeration of oxide particles was observed. However, even at 400 deg. C, metallic Ru was detected by XRD, TEM and SAED suggesting that large metal particles were not fully oxidized under the used conditions. Also, the O{sub 2} uptake at 400 deg. C was lower than expected for oxidation of Ru metal to RuO{sub 2}. For the catalyst after elimination Cl ions the O{sub 2} uptake (O/Ru ratio = 1.50) was higher, than for sample with large amount of Cl ions (O/Ru ratio = 1.34), indicating that the presence of Cl inhibits ruthenium oxidation in the Ru/Al{sub 2}O{sub 3} catalyst.

• OSTI ID: 21199669
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 2 Vol. 44; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
CATALYSTS
CHEMISORPTION
CHLORINE IONS
CRYSTALLIZATION
ELECTRON DIFFRACTION
HYDROGEN
LAYERS
NANOSTRUCTURES
OXIDATION
PARTICLE SIZE
RUTHENIUM
RUTHENIUM CHLORIDES
RUTHENIUM OXIDES
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
UPTAKE
X-RAY DIFFRACTION