Highly efficient hydrogen and ethylene glycol photoproduction from aqueous methanol solution by ZnS and an in situ spin trapping investigation

Abstract

The search for a more efficient production of hydrogen and ethylene glycol from aqueous methanol solution in the presence of ZnS colloid and UV irradiation is reported. The yields of hydrogen and ethylene glycol and the selectivity of ethylene glycol are strongly dependent on the initial pH and the reaction temperature. The selectivity of ethylene glycol can reach 95%. Spin trapping was employed to detect the radical intermediates formed during in situ irradiation of ZnS in aqueous methanol solution. Phenyl- N- tert-butyl nitrone (PBN) can be used as a spin trap. It was confirmed that CH 2OH is the major radical intermediate in the alkaline reaction system. The coupling of CH 2OH is the main method of formation of ethylene glycol.