The selective oxidation of toluene to benzaldehyde applying a fuel cell system in the gas phase

Journal Article · Fri Nov 01 00:00:00 EST 1991 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2085388· OSTI ID:7167087

Otsuka, K; Ishizuka, K; Yamanaka, I; Hatano, M ^[1]

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1. Dept. of Chemical Engineering, Tokyo Inst. of Technology, Ookayama, Meguro-ku, Tokyo 152 (JP)

This paper discusses a fuel cell system used for the synthesis of benzaldehyde from toluene in the gas phase. The cell system (anode: Pd-black with added graphite/H{sub 3}PO{sub 4}(aq.)/cathode: Pt-black with added graphite) operated at ca. 373 K under short-circuit conditions and produced the partial oxidation products benzaldehyde (PhCHO) and benzoic acid (PhCOOH). The addition of chlorides such as HCl, NaCl, MgCl{sub 2}, etc., to the anode remarkably improved the selectivity of the sum of PhCHO and PhCOOH. In the presence of chlorides, CO{sub 2} was not produced at all. Among the chlorides tested, NaCl is the best additive for the synthesis of PhCHO. Kinetic results on the reaction with the NaCl-added anode have shown that decreasing temperatures and increasing pressures of the reactants (toluene and O{sub 2}) favor the oxidation to PhCHO. The oxidation of toluene under an externally applied potential showed a product distribution similar to that observed under short-circuit conditions. The turnover number grater than unite (2.4) indicates catalytic cycling of the Pd in the anode. The current efficiency was improved by cyclic short- and open-circuit operation of the cell. A reaction mechanism assuming a {pi} allylbenzyl-Pd{sup 2+} (ligand){sub x} complex as the reaction intermediate explains the kinetic results and the favorable effect of chloride. The intermediate complex may be generated through the electrochemical oxidation of Pd and toluene. The subsequent competitive formations of PhCHO and CO{sub 2} from this complex proceed nonelectrochemically.

• OSTI ID: 7167087
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 138:11; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BENZALDEHYDE
SYNTHESIS
FUEL CELLS
USES
PALLADIUM
OXIDATION
TOLUENE
CHEMICAL REACTION KINETICS
ELECTROCATALYSTS
ELECTROCHEMISTRY
ALDEHYDES
ALKYLATED AROMATICS
AROMATICS
CATALYSTS
CHEMICAL REACTIONS
CHEMISTRY
DIRECT ENERGY CONVERTERS
ELECTROCHEMICAL CELLS
ELEMENTS
HYDROCARBONS
KINETICS
METALS
ORGANIC COMPOUNDS
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENTS
300504* - Fuel Cells- Applications
300505 - Fuel Cells- Electrochemistry
Mass Transfer & Thermodynamics
400400 - Electrochemistry