Role of the different catalytic sites in the H2O2-mediated aqueous-phase furfural partial oxidation
Paula Rapado, Laura Faba, Salvador Ordóñez
Abstract
The potential of hydrogen peroxide as oxidizing agent for furfural partial oxidation is studied in this work. Hydrogen peroxide is proposed as an alternative to air, the most typical oxidant, to reduce the severity and complexity of the process, as the reaction occurs in the liquid phase at ambient pressure. Comparing the activity of different catalysts and the selectivity for different oxidation products, including furoic acid, 2(5H)furanone, and maleic and malic acids, a comprehensive mechanistic kinetic model is presented. This model identifies the critical catalytic properties ruling the selectivity of the process for each target compound. The results of this study emphasize the role of acidity in promoting the oxidations, the function of basicity for stabilizing the intermediate acids, and the impact of redox properties and metal particle size, which synergistically influence selectivity. This study concludes that Au/TiO2 is the optimum catalyst to produce furoic acid (42% of selectivity). Additionally, Pt/MgZr selectively produces 2(5H)furanone (100%), and Pd/TiO2 and Pt/CeO2 maximize the production of maleic acid (76.5%) and malic acid (78.5%), respectively.