Hydrogen evolution from the photolysis of alcoholic benzophenone solutions via redox catalysis

Journal Article · Wed Dec 19 04:00:00 EST 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00520a032· OSTI ID:5666754

Graetzel, C K; Graetzel, M

The overall process catalyzed by the platinum sol is the benzophenone-sensitized dehydrogenation of 2-propanol. The standard enthalpy of the reaction is positive, which makes this process light energy storing. The mechanism derived from the laser photolysis studies is corroborated by results obtained from continuous illumination of alcoholic benzophenone solution. Spectrophotometric data obtained before and after irradiation of samples with and without catalyst are compared. In the case of the Pt-free solution a photolysis time of 30 m suffices to remove >70% of the benzophenone absorption at 260 nm. In contrast, one finds practically no depletion of benzophenone under illumination if the platinum catalyst is present. Hydrogen is evolved, as shown by gas chromatographic analysis. The catalyst can intervene efficiently to prevent ketyl radical dismutation making feasible stoichiometric water reduction. In the presence of Pt catalyst, benzophenone sensitizes the dehydrogenation of 2-propanol to acetone. 2 figures.

• Research Organization: Ecole Polytechnique Federale, Lausanne, Switzerland
• OSTI ID: 5666754
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:26; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
080106* -- Hydrogen-- Production-- Biosynthesis & Photochemical Processes
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ABSORPTION SPECTRA
ACETONE
ALCOHOLS
BENZOPHENONE
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHROMATOGRAPHY
DECOMPOSITION
DEHYDROGENATION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENTHALPY
GAS CHROMATOGRAPHY
HYDROGEN COMPOUNDS
HYDROGEN PRODUCTION
HYDROXY COMPOUNDS
KETONES
KINETICS
LASER RADIATION
METALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHYSICAL PROPERTIES
PLATINUM
PLATINUM METALS
PROPANOLS
RADIATIONS
REACTION KINETICS
REAGENTS
REDOX REACTIONS
REDUCTION
SENSITIZERS
SEPARATION PROCESSES
SPECTRA
STOICHIOMETRY
THERMODYNAMIC PROPERTIES
TIME DEPENDENCE
TRANSITION ELEMENTS
WATER
YIELDS