Oxidative pyrolysis reforming of methanol in warm plasma for an on-board hydrogen production

Abstract

To achieve on-board hydrogen production with high energy efficiency and low energy cost, the oxidative pyrolysis reforming (OPR) of methanol using air as an oxidant in a heat-insulated gliding arc plasma reactor is explored. Effects of dioxygen/methanol (O2/C) ratio, steam/methanol (S/C) ratio and specific energy input (SEI) on the OPR are investigated. The reaction rate ratio (α) of pyrolysis reforming to oxidative reforming in the OPR is deduced. The OPR of methanol strongly depends on the O2/C ratio, with which methanol conversion increases rapidly. In the OPR, methanol conversions occur mainly by the oxidative reforming (partial oxidation) at the O2/C ratios below 0.20, but by the oxidative reforming and the promoted pyrolysis reforming at the O2/C ratios above 0.20, which is confirmed by the enthalpy change for the overall reaction of OPR. Higher O2/C ratio results in higher energy efficiency and lower energy cost, however, higher S/C ratio or larger SEI leads to lower energy efficiency and higher energy cost. Under conditions of O2/C = 0.30, S/C = 0.5, SEI = 24 kJ/mol, energy efficiency of 74% and energy cost of 0.45 kWh/Nm3 with methanol conversion of 88% are achieved.