Sugar acids obtained by oxidation of sugars are very valuable molecules which are used as chelating agents, binders as well as ingredients in pharmaceuticals. Arabinonic acid was prepared by oxidation of arabinose on gold nanoparticles deposited on an aluminium oxide carrier. A systematic kinetic study was conducted to reveal the influence of oxygen partial pressure and the pH on the reaction rate and product selectivity. Experiments were carried out in a laboratory-scale semi-batch reactor which was operated at 70°C and oxygen partial pressures 0.125-1.0 atm. The pH of the aqueous sugar solution was 6-8. Oxygen was continuously flowing through the semibatch slurry reactor and the pH was kept constant by adding NaOH during the experiments. The oxygen solubility in the reaction mixture was determined by separate experiments. A reaction mechanism was proposed for the formation of arabinonic acid (main product) and arabinolactone (intermediate by-product). The surface reaction of competitively adsorbed arabinose and oxygen was assumed to be rate determining for the arabinose consumption. For the formation of arabinonic acid from arabinolactone, the rate determining step was presumed to be the reaction between arabinolactone and sodium hydroxide. The reactor was described with the perfect backmixing model and the component mass balances were solved numerically during the estimation of kinetic parameters by nonlinear regression analysis. The kinetic model gave new insights in the reaction mechanism and described the experimental data very well. The model has perspective in the oxidation of other monomeric sugars, too.

通过糖的氧化获得的糖酸是非常有价值的分子，可用作螯合剂、粘合剂以及药物中的成分。通过在沉积在氧化铝载体上的金纳米粒子上氧化阿拉伯糖来制备阿拉伯糖酸。进行了系统的动力学研究，以揭示氧分压和 pH 值对反应速率和产物选择性的影响。实验在实验室规模的半间歇式反应器中进行，该反应器在 70°C 和氧分压 0.125-1.0 atm 下运行。糖水溶液的pH为6-8。氧气连续流过半间歇式浆料反应器，并且在实验过程中通过添加 NaOH 使 pH 值保持恒定。反应混合物中的氧溶解度通过单独的实验确定。提出了形成阿拉伯糖酸（主要产物）和阿拉伯糖内酯（中间副产物）的反应机理。假设竞争吸附的阿拉伯糖和氧气的表面反应是阿拉伯糖消耗的速率决定因素。对于从阿拉伯内酯形成阿拉伯酸，速率确定步骤被假定为阿拉伯内酯和氢氧化钠之间的反应。反应器采用完美的反混模型进行描述，并在通过非线性回归分析估计动力学参数的过程中对组分质量平衡进行了数值求解。动力学模型为反应机理提供了新的见解，并很好地描述了实验数据。该模型也具有其他单糖氧化的前景。