Aerobic selective oxidation of glucose to gluconate catalyzed by Au/Al2O3 and Au/C: Impact of the mass-transfer processes on the overall kinetics

作者：Delidovich Irina V; Moroz Boris L; Taran Oxana P^*; Gromov Nikolay V; Pyrjaev Pavel A; Prosvirin Igor P; Bukhtiyarov Valerii I; Parmon Valentin N

来源：Chemical Engineering Journal, 2013, 223: 921-931.

DOI：10.1016/j.cej.2012.11.073

• Selective oxidation
• Gold catalyst
• Carbon
• Alumina
• Glucose
• Gluconic acid
• Mass transfer

Aerobic oxidation of glucose in the presence of Au/Al2O3 catalysts with different dispersion of supported gold and Au/C catalysts containing highly dispersed gold nanoparticles was studied at varied glucose:Au molar ratios. The studies were focused on determining the contribution of the mass-transfer processes to the overall reaction kinetics in different regimes. The Au/Al2O3 catalysts were more active than the Au/C catalysts at high glucose:Au molar ratios. Among the alumina-supported catalysts with different metal dispersion, the highest TOF at high glucose:Au molar ratios was characteristic of the Au/Al2O3 catalysts bearing metal particles of 1-5 nm in size. Under these conditions, the high effectiveness factor of the Au/Al2O3 catalysts (%26gt;95%) was observed at a uniform gold distribution through the support granules. For the Au/C catalysts with the non-uniform distribution of gold nanoparticles through the catalyst grains, the apparent reaction rate was affected by internal diffusion (the effectiveness factor of a catalyst grain is ca. 70%), while the interface gas liquid solid oxygen transfer influenced the overall reaction kinetics as well. At a low glucose:Au molar ratio the reaction rate was limited by oxygen dissolution in the aqueous phase. In this mass transfer regime the rate of glucose oxidation over the carbon-supported catalysts exceeds the reaction rate over the alumina-supported catalyst, which is attributed to a higher adhesion of the hydrophobic carbon support to the gas liquid interface facilitating the oxygen mass transfer towards catalytic sites.

• 出版日期2013-5-1