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Selective Oxidation of D ‐Galactose over Gold Catalysts
Author(s) -
Kusema Bright T.,
Campo Betiana C.,
Simakova Olga A.,
Leino AnneRiika,
Kordás Krisztián,
MäkiArvela Päivi,
Salmi Tapio,
Murzin Dmitry Yu
Publication year - 2011
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201100183
Subject(s) - catalysis , selectivity , chemistry , calcination , particle size , inorganic chemistry , galactose , nuclear chemistry , organic chemistry
The selective oxidation of D ‐galactose to galactonic acid over Au/Al 2 O 3 was studied isothermally in a semi‐batch shaker reactor under pH‐controlled conditions at atmospheric pressure. A series of Au/Al 2 O 3 catalysts were prepared and calcined at different temperatures to achieve different gold‐particle sizes. The catalytic properties of the gold nanoparticles were affected by the cluster size. A detailed comparison of activity and selectivity of these catalysts was made, which demonstrated that Au/Al 2 O 3 with a mean particle size of 2.6 nm exhibited the highest activity. The influence of the pH value of the reaction medium on the selective oxidation of D ‐galactose was elucidated. Alkaline conditions were characterized by high catalyst activity and selectivity to aldonic acid. Inhibition of the catalytic activity was observed in the acidic medium. The intermediate species was present at low pH values, and this resulted in low conversion and selectivity to the main product, galactonic acid. The electrochemical potential of the catalyst was correlated to the catalytic activity.