Selective catalytic oxidation of arabinose—A comparison of gold and palladium catalysts

Selective Oxidation of D‐Galactose over Gold Catalysts

“…[8] A typical concentration curve and electrochemical potential of the catalyst of the d-galactose oxidation over 2.6 nm 2 wt % Au/Al 2 O 3 at pH 8 are shown in Figure 3. The oxygen flow rate was 2.5 mL min À1 , and the pH value of the reaction medium was systematically varied in the range of 6-10.…”

“…[8] Different reaction parameters, such as temperature and oxygen flow rates, were investigated, and it was concluded that the moderate and optimized conditions of 60 8C, oxygen flow rate of 2.5 mL min À1 , and pH 8 were sufficient to achieve complete conversion without further degradation of the products at prolonged reaction times. [8] Different reaction parameters, such as temperature and oxygen flow rates, were investigated, and it was concluded that the moderate and optimized conditions of 60 8C, oxygen flow rate of 2.5 mL min À1 , and pH 8 were sufficient to achieve complete conversion without further degradation of the products at prolonged reaction times.…”

“…[8,22,31] The effect of the pH value is, therefore, crucial in the oxidation of sugars. First, an increase in the pH value, that is, an alkaline medium, increases the rate of oxidation.…”

“…[1,2] Supported gold nanoparticles exhibit an exceptionally low-temperature catalytic activity and high selectivity in the oxidation of carbohydrates, alcohols, and hydrocarbons. [8] It has also been observed that the oxidation reactions exhibit structure sensitivity, that is, the catalyst activity is influenced by the size of the gold nanoparticles. Gold also shows superior durability and stability because of its high resistance to deactivation caused by overoxidation and poisoning of the active metal.…”

Catalytic Oxidation Pathways for the Production of Carboxylic Acids from Biomass

“…Selective oxidation of arabinose to arabinonic acid was carried out over Pd-Au/Al 2 O 3 and Pd-Au/CeO 2 catalysts, prepared by deposition-precipitation method using HAuCl 4 and urea with subsequent chemisorption of palladium using PdCl 2 , at moderate conditions of 60 °C and pH 8; gold metallic species seemed to be responsible for the arabinose activation, while Pd species effected oxygen activation [ 93 ]. Higher catalyst activity and selectivity to arabinonic acid were achieved with Au/Al 2 O 3 than Pd /Al 2 O 3 due to the increase of the amount of by-products on the Pd catalyst [ 133 ]. An oxidative dehydrogenation mechanism was proposed, and a kinetic model taking into account the catalyst potential changes was developed for the selective oxidation of L -arabinose over Au/ Al 2 O 3 catalysts [ 134 ].…”