TY - JOUR
T1 - Catalytic oxidation of cellobiose over TiO2 supported gold-based bimetallic nanoparticles
AU - Amaniampong, Prince Nana
AU - Jia, Xinli
AU - Wang, Bo
AU - Mushrif, Samir H.
AU - Borgna, Armando
AU - Yang, Yanhui
N1 - Publisher Copyright:
© The Royal Society of Chemistry 2015.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - A series of Au-M (M = Cu, Co, Ru and Pd) bimetallic catalysts were supported on TiO2via a deposition-precipitation (DP) method, using urea as a precipitating agent. The resulting catalysts were employed in the catalytic oxidation of cellobiose to gluconic acid and the properties of these catalysts were carefully examined using various characterization techniques. Cu-Au/TiO2 and Ru-Au/TiO2 catalysts demonstrated excellent catalytic activities in the oxidation of cellobiose to gluconic acid, though with contrasting reaction mechanisms. Complete conversion of cellobiose (100%) with a gluconic acid selectivity of 88.5% at 145 °C within 3 h was observed for reactions performed over Cu-Au/TiO2; whereas, a conversion of 98.3% with a gluconic acid selectivity of 86. 9% at 145°C within 9 h was observed for reactions performed over Ru-Au/TiO2. A reaction pathway was proposed based on the distribution of reaction products and kinetic data. It is suggested that cellobiose is converted to cellobionic acid (4-O-beta-d-glucopyranosyl-d-gluconic acid) and then gluconic acid is formed through the cleavage of the β-1,4 glycosidic bond in cellobionic acid over Cu-Au/TiO2 catalysts. On the other hand, for reactions over the Ru-Au/TiO2 catalyst, glucose was observed as the reaction intermediate and gluconic acid was formed as a result of glucose oxidation. For reactions over Co-Au/TiO2 and Pd-Au/TiO2 catalysts, fructose was observed as the reaction intermediate, along with small amounts of glucose. Co and Pd remarkably promoted the successive retro-aldol condensation reactions of fructose to glycolic acid, instead of the selective oxidation to gluconic acid.
AB - A series of Au-M (M = Cu, Co, Ru and Pd) bimetallic catalysts were supported on TiO2via a deposition-precipitation (DP) method, using urea as a precipitating agent. The resulting catalysts were employed in the catalytic oxidation of cellobiose to gluconic acid and the properties of these catalysts were carefully examined using various characterization techniques. Cu-Au/TiO2 and Ru-Au/TiO2 catalysts demonstrated excellent catalytic activities in the oxidation of cellobiose to gluconic acid, though with contrasting reaction mechanisms. Complete conversion of cellobiose (100%) with a gluconic acid selectivity of 88.5% at 145 °C within 3 h was observed for reactions performed over Cu-Au/TiO2; whereas, a conversion of 98.3% with a gluconic acid selectivity of 86. 9% at 145°C within 9 h was observed for reactions performed over Ru-Au/TiO2. A reaction pathway was proposed based on the distribution of reaction products and kinetic data. It is suggested that cellobiose is converted to cellobionic acid (4-O-beta-d-glucopyranosyl-d-gluconic acid) and then gluconic acid is formed through the cleavage of the β-1,4 glycosidic bond in cellobionic acid over Cu-Au/TiO2 catalysts. On the other hand, for reactions over the Ru-Au/TiO2 catalyst, glucose was observed as the reaction intermediate and gluconic acid was formed as a result of glucose oxidation. For reactions over Co-Au/TiO2 and Pd-Au/TiO2 catalysts, fructose was observed as the reaction intermediate, along with small amounts of glucose. Co and Pd remarkably promoted the successive retro-aldol condensation reactions of fructose to glycolic acid, instead of the selective oxidation to gluconic acid.
UR - http://www.scopus.com/inward/record.url?scp=84925935585&partnerID=8YFLogxK
U2 - 10.1039/c4cy01566e
DO - 10.1039/c4cy01566e
M3 - 文章
AN - SCOPUS:84925935585
SN - 2044-4753
VL - 5
SP - 2393
EP - 2405
JO - Catalysis Science and Technology
JF - Catalysis Science and Technology
IS - 4
ER -