Oxidation characteristics and products of five ethers at low temperature

The oxidation characteristics and products of five ethers - ethyl tert-butyl ether (ETBE), methyl tert-butyl ether (MTBE), dimethyl ether (DME), diethyl ether (DEE), and diisopropyl ether (DIPE) - were determined using an accelerating rate calorimeter (ARC) at low temperatures. Oxidation temperature and pressure were calculated using temperature-time (T-t) and pressure-time (P-t) plots, and reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that the oxidation reaction pathway of ethers with oxygen occurred in three stages: (1) promotion of oxygen and peroxide absorption by ether; (2) generation of free radicals by thermal decomposition; and (3) complex oxidation caused by free radicals. Initial auto-oxidation temperatures of DME, DEE, DIPE, MTBE, and ETBE were approximately 393 K, 389 K, 359 K, 413 K, and 383 K, respectively, and the activation energies (Ea) for thermal decomposition were 167.3 kJ/mol, 126.7 kJ/mol, 111.6 kJ/mol, 236.7 kJ/mol, and 159.1 kJ/mol, respectively, for the first-order reaction. Peroxides of DEE, DIPE, MTBE, and ETBE were identified by iodimetry analysis when oxidation temperature was 333 K. Oxidation reaction products were complex and included alcohols, aldehydes, ketones, acids, esters, and carbon dioxide.