A customer-designed
mini closed pressure vessel test (MCPVT) consisting
of a pressure sensor and a temperature sensor connected to recorder
was applied to evaluate the isothermal stability along with the formation
of hydroperoxide in the ethyl t-butyl ether (ETBE)
oxidation process at low temperatures. A new type of hydroperoxide,
named 1-tert-butoxy-ethyl hydroperoxide (TBEHP),
was separated from ETBE oxidation products via column chromatography,
which was further characterized by mass spectrometry (MS), 1H and 13C nuclear magnetic resonance (NMR), and Fourier
transform infrared spectroscopy (FTIR). The thermal characteristics
of TBEHP were assessed via differential scanning calorimetry (DSC).
Results showed that the exothermic onset temperature (T
0) and thermal decomposition heat (Q
DSC) of TBEHP were 99.12 °C and 1523.89 J·g–1, respectively. Moreover, a jet-stirred reactor (vessel volume: 500
mL) was used to evaluate the explosive risk of ETBE oxidation. The
corresponding result indicated that detonation would arise in conditions
of reaching system temperature of 140.0 °C, sample mass of 5.0
g, and oxygen pressure of 1.0 MPa, respectively. Finally, it was confirmed
that ETBE thermal oxidation was a three-step exothermic reaction including
the formation of hydroperoxide by absorbing oxygen, followed by the
thermal decomposition of hydroperoxide, and subsequently deep oxidation
reactions or detonation caused by reactive free radicals.