Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Glyoxal with platinum

In acidic medium, the electrocatalytic oxidation of glyoxal on platinum in the potential range 1 to 1.5 V/RHE leads mainly to formic acid (60%) and CO (40%). With lead adatoms, it becomes possible to oxidize glyoxal between 0.4 and 1.0 V/RHE leading mainly to CO2 formation (46%), while the selectivity towards, glyoxylic acid is sensibly increased (28%). At pH=7 and 1,9 V/RHE, the main oxidation product is formic acid (99%). Otherwise, in acidic medium the oxidation is more selective towards glyoxylic acid (70%), when the applied potential is in the range of 1.80 to 2.13 V/RHE. [Pg.463]

Glyoxylic acid (CHOCOOH), used in the preparation of fine chemicals (e. g., vanillin and penicillin), is prepared industrially by oxidation of glyoxal with nitric acid. An attempt was made to replace this stoichiometric process by oxidation of glyoxal with air on platinum catalysts [57-59]. In a first series of experiments, catalysts containing different platinum metals (Pt, Ir, Pd, Rh, Ru) prepared on the same active carbon and with the same particle size (1-2 nm) were compared. The initial rate of reaction increased in the sequence 0 = Ru < Rh < Pd < Ir < Pt, which is similar to that of the redox potentials of these elements. [Pg.497]

The chemoselectivity can be strongly changed by the anode material. The oxidation of glycolaldehyde at a platinum anode affords mainly glyoxal while the conversion with a platinum anode modified by antimony or bismuth ad-atoms provides mainly glycolic acid (Fig. 29) [147]. [Pg.416]

These results are, in some sense, consistent with those of Pierre et. al.[3]. These authors showed that glyoxal electrolysis under galvanostatic conditions (1 A dm 2) on platinum in perchloric acid medium leads to 39% of GA, the potential applied between the two electrodes being in the range of 2 -6 V/RHE. [Pg.469]


See other pages where Glyoxal with platinum is mentioned: [Pg.465]    [Pg.81]    [Pg.149]    [Pg.493]    [Pg.497]    [Pg.622]   
See also in sourсe #XX -- [ Pg.497 ]




SEARCH



Glyoxalate

Glyoxalic

Glyoxals

© 2024 chempedia.info