The effect of chlorine on hydrogen chemisorption by silica-supported Ru catalysts: A proton NMR study

Journal Article · Fri May 01 04:00:00 EDT 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90269-N· OSTI ID:6915949

Wu, X; Gerstein, B C; King, T S ^[1]

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1. Iowa State Univ., Ames (United States)

Silica-supported ruthenium catalysts prepared from the RuCl[sub 3] [center dot] 3H[sub 2]O precursor contain residual chloride after reduction in flowing hydrogen. The amount of this chlorine was determined by X-ray fluorescence spectroscopy to be less than one monolayer on the ruthenium surfaces. Both volumetric hydrogen chemisorption and proton NMR show suppression of hydrogen chemisorption capacity associated with the presence of chlorine contamination, which can be removed effectively with hot water elution. The variations of the hydrogen chemisorption capacity with chlorine coverage suggests that chlorine would completely block and poison the Ru surfaces for hydrogen chemisorption at a Cl coverage of about 76%. The effect of residual chloride on the proton NMR resonance position and the spin-lattice relaxation time for the chemisorbed hydrogen indicates an electronic interaction between Cl adspecies and surface Ru, which results in the weakening of the H-Ru[sub 5] chemisorptive bond at the Ru surfaces. This reduced H-Ru[sub 5] interaction may be the cause for an increase in the ratio of the reversibly adsorbed hydrogen over the irreversibly adsorbed hydrogen with increasing Cl coverage. It is proposed that the mechanism for suppression of hydrogen chemisorption by chlorine involves both physical site blocking of surface Ru atoms and short-ranged electronic interactions between Cl adatoms and neighboring surface Ru atoms.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6915949
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 135:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
CHLORINE
CONTAMINATION
ELEMENTS
HALOGENS
HYDROGEN
MAGNETIC RESONANCE
METALS
NONDESTRUCTIVE ANALYSIS
NONMETALS
NUCLEAR MAGNETIC RESONANCE
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
POISONING
REMOVAL
RESONANCE
RUTHENIUM
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS
X-RAY EMISSION ANALYSIS
X-RAY FLUORESCENCE ANALYSIS