Hydrogen adsorption and hydrogen-deuterium equilibration on sulfided ruthenium and bulk ruthenium sulfide catalysts

Journal Article · Sat Apr 01 00:00:00 EST 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90104-8· OSTI ID:6224840

Lu, K; Kuo, Y J; Tatarchuk, B J ^[1]

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1. Auburn Univ., AL (USA)

The effect of presulfidization on hydrogen adsorption over ruthenium catalysts has been studied using volumetric adsorption and H{sub 2}-D{sub 2} equilibration. On reduced ruthenium catalysts (101 kPa of H{sub 2} at 673 K for 8 h) 10.2 {mu}mol of H{sub 2}/M{sub 2} of ruthenium (measured at 373 K) was irreversibly adsorbed, the activation energy for adsorption was negligible and the initial heat of adsorption was estimated to be between {minus}109 and {minus}126 kJ/mole H{sub 2}. On mildly sulfided ruthenium catalysts (101 of kPa 10% H{sub 2}S/H{sub 2} at 673 K for 2 h, S{sub a}/Ru{sub (s)} = 0.25) both reversible and irreversible hydrogen adsorption were suppressed at temperatures below 473 K. Results of H{sub 2}-D{sub 2} equilibration kinetics on these catalysts (508 {le} T {le} 623 K) revealed an activation energy of 71 {+-} 2 kJ/mole. On extensively sulfided ruthenium catalysts (101 kPa of 100% H{sub 2}S at 673 K for 2 h, i.e., crystalline RuS{sub 2} at the surface) partial restoration of the H{sub 2} adsorption capacity was observed (6.5 {mu}mol/m{sup 2} at 373 K). H{sub 2}-D{sub 2} exchange rates at 573 K were Ca. two orders of magnitude faster than those over mildly sulfided samples. The activation energy for hydrogen adsorption was 32 {+-} 2 kJ/mole (on RuS{sub 2}-like surfaces) and the heat of adsorption was calculated to be {minus}269 kJ/mole H{sub 2}. It is suspected that this large heat of adsorption may result in higher hydrogen coverages at HDS reaction conditions. The above noted differences in hydrogen accommodation provide a unique means for understanding the selectivity toward hydrogenated products which extensively sulfided ruthenium catalysts possess. 28 refs.

• OSTI ID: 6224840
• Journal Information: Journal of Catalysis; (USA), Vol. 116:2; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
02 PETROLEUM
RUTHENIUM SULFIDES
SORPTIVE PROPERTIES
THIOPHENE
DESULFURIZATION
ACTIVATION ENERGY
ADSORPTION
ADSORPTION HEAT
CATALYSTS
CATALYTIC EFFECTS
DEUTERIUM
HYDROGEN
HYDROGEN SULFIDES
ISOTOPIC EXCHANGE
SULFIDATION
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
ENERGY
ENTHALPY
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
RUTHENIUM COMPOUNDS
SORPTION
STABLE ISOTOPES
SULFIDES
SULFUR COMPOUNDS
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
010402* - Coal
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