The corrosion of 316L stainless steel was examined in a high-temperature and
high-pressure methanol solution containing chloride ions as decomposition system reactor
material using subcritical or supercritical methanol. Surface morphology of corrosion reactions
on the sample immersed in a deaerated or aerated anhydrous methanol solution containing
0.53 wt% LiCI at 323 - 473 K were observed. Below 423 K, pitting corrosion was observed in
all methanol solutions. On the other hand, at 473 K, pitting corrosion was not observed in spite
of higher temperature. The results of electrochemical impedance spectroscopy and cathodic
polarization measurements in deaerated methanol solution revealed that the cathode reaction
was reduction of proton derived from the dissociation of methanol at high temperature and that
the nature of the passive film varied during immersion in the methanol solution. Based on the
result of XPS C1 s spectra, it is suggested that passive film formed in the methanol solution
was composed of the decomposition products of methanol.