Aerobic Oxidation of Methyl Glycolate by α-Fe<sub>2</sub>O<sub>3</sub> for the Eco-Friendly Synthesis of Methyl Glyoxylate
Hao Wang, Tian Lan, Guofeng Zhao, Guoqing Chen, Yong Lu
Abstract
Methyl glyoxylate (MGO) is an important reagent for value-added chemical and pharmaceutical synthesis, but it urgently requires an eco-friendly synthesis method. Aerobic oxidation of massively obtainable methyl glycolate (MG) is an ideal nonpetrochemical route for MGO production. Herein, α-Fe 2 O 3 with a hydroxyl-deficient surface obtained by a precipitation method is discovered to be an enabling catalyst with a markedly lowered reaction activation energy (88.6 kJ mol –1 ), achieving a high specific activity of 0.26 g MGO m cat –2 h –1 . The MG conversion of 80–85% and 90–92% MGO selectivity are obtained at 220 °C and can maintain stability throughout 100 h test. Isotope-labeling experiments and theoretical calculations confirm that this reaction proceeds over α-Fe 2 O 3 following the MvK mechanism. The hydroxyl-deficient surface provides a warranty for such unprecedented catalytic performance, which in nature offers highly reactive lattice oxygen and abundant accessible Fe sites, thereby benefiting MG adsorption/activation, and is conducive to water desorption due to enhanced hydrophobicity.