Regulation of reaction intermediate by reactant in the water-gas shift reaction on CeO sub 2 , in relation to reactant-promoted mechanism

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

DOI:https://doi.org/10.1016/0021-9517(92)90079-W· OSTI ID:7252977

Shido, Takafumi; Iwasawa, Yasuhiro ^[1]

---

1. Univ. of Tokyo, Hongo (Japan)

Reaction regulation by intermediate-reactant interaction in the water-gas shift reaction (H{sub 2}O + CO {yields} H{sub 2} + CO{sub 2}; WGSR) on CeO{sub 2} was investigated in relation to the reactant-promoted mechanism on MgO and ZnO by FT-IR. Terminal OH groups on partially reduced CeO{sub 2} reacted with CO to produce bridge formates. Bridge formates were converted to bidentate formates above 443 K, and this transformation occurred at room temperature when water coexisted. The decomposition of the surface formates was affected by the water molecule; 70% of the bidentate formates decomposed to OH + CO (backward decomposition) and 30% of them decomposed to H{sub 2} + CO{sub 2}. The activation energy increased from 94 kJ/mol without water to 193 kJ/mol with water. Isotope effects were observed on the hydrogen atoms of both formate and hydroxyl, giving a proposed transition state in the reaction mechanism. The bidentate formates reacted with the adjacent hollow-site OH to decompose to H{sub 2} and unidentate carbonates. The decomposition of the unidentate carbonates to CO{sub 2} was promoted by coadsorbed water. The results are also discussed in comparison with the results for WGSR and MgO and ZnO.

• OSTI ID: 7252977
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 136:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
08 HYDROGEN
080104 -- Hydrogen-- Production-- Water Gas Processes
33 ADVANCED PROPULSION SYSTEMS
330702 -- Emission Control-- Carbon Monoxide
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
ACTIVATION ENERGY
ALKALINE EARTH METAL COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACID SALTS
CATALYTIC EFFECTS
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY
EVALUATION
FORMATES
FOURIER TRANSFORMATION
HYDROGEN
INFRARED RADIATION
INTEGRAL TRANSFORMATIONS
ISOTOPE EFFECTS
KINETICS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
RARE EARTH COMPOUNDS
REACTION INTERMEDIATES
REACTION KINETICS
SHIFT PROCESSES
SPECTROSCOPY
SYNTHESIS
TRANSFORMATIONS
WATER GAS PROCESSES
ZINC COMPOUNDS
ZINC OXIDES