Disclosure of water roles in gliding arc plasma reforming of methanol for hydrogen production

To disclose water roles in plasma reforming of methanol for hydrogen production, gliding arc discharge characteristics, optical emission spectra, and reaction behavior are investigated over a water concentration range of 0-95 mol%. It can be concluded that the varied reaction behavior with water concentration derives from three water roles as a homogeneous catalyst, CO oxidant, and side-product. The former two roles of water are beneficial for hydrogen production. The side-product role of water, accompanied by hydrocarbons formation, which is disadvantageous to hydrogen production and can be almost fully inhibited by the homogeneous catalysis of water at above 33 mol% H2O. As an oxidant, water conversion is controlled by the thermodynamic equilibrium at the gas temperature of arc.