Influence of the carrier on the interaction of H[sub 2] and CO with supported Rh

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1090· OSTI ID:7368959

Ioannides, T; Verykios, X ^[1]

---

1. Univ. of Patras (Greece)

The influence of the carrier (SiO[sub 2], Al[sub 2]O[sub 3], and TiO[sub 2]) on the interaction of supported Rh with H[sub 2] and CO and on kinetic parameters in CO hydrogenation is investigated employing transient and steady-state techniques. TPD of H[sub 2] revealed two modes of adsorption on Rh/Al[sub 2]O[sub 3] and Rh/TiO[sub 2], one of which is activated. This was not observed over Rh/SiO[sub 2]. TPD spectra obtained following CO adsorption reveal significant differences, depending on the carrier. Three major states of desorbing CO were detected, one of which desorbs as CO[sub 2] accompanied by H[sub 2] evolution. In Rh/SiO[sub 2] and Rh/Al[sub 2]O[sub 3] the weakly adsorbed CO exhibits peak maximum temperatures in the range 90-100[degrees]C, while for the strongly adsorbed CO these are in the range 263--270[degrees]C in Rh/SiO[sub 2] and 210--245[degrees]C in Rh/Al[sub 2]O[sub 3]. In both cases, the CO[sub 2] peak maximum appears in the range 340--355[degrees]C. The activity of the catalysts toward CO decomposition was found to decrease in the order: Rh/TiO[sub 2] [much gt] Rh/Al[sub 2]O[sub 3] > Rh/SiO[sub 2]. This observation has been attributed to the creation of new adsorption sites at the Rh-TiO[sub 2] interface and carrier participation in the process of CO decomposition. The reactivity of adsorbed CO toward hydrogenation, as investigated by TPR experiments, was found to follow the same order as that for CO decomposition. The Rh/TiO[sub 2] catalyst was found to be 15-20 times more active in steady-state CO hydrogenation, as compared to Rh/SiO[sub 2] and Rh/Al[sub 2]O[sub 3], and to exhibit lower activation energies for methanation and water-gas shift reactions. 44 refs., 6 figs., 5 tabs.

• OSTI ID: 7368959
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 140:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010408 -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
DESORPTION
ELEMENTS
ENERGY
FLUIDS
FUEL GAS
FUELS
GAS FUELS
GASES
HYDROGEN
HYDROGENATION
INTERMEDIATE BTU GAS
KINETICS
METHANATION
NONMETALS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RHODIUM COMPOUNDS
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
WATER GAS