Generation of ultra-clean fuel from Victorian brown coal - Synchrotron XANES study on the evolution of sulphur in Victorian brown coal upon hydrothermal upgrading treatment and thermal pyrolysis

► The heterocyclic thiophene and sulphidic sulphur are predominant in Victorian brown coal. ► Increasing the hydrothermal leaching temperature favoured the conversion from sulphidic acid to thiophene. ► The evolution of sulphur during brown coal pyrolysis was dominated by the conversion of sulphide to thiophene at 400 °C. ► Increasing pyrolysis temperature to 800 °C favoured the capture of a portion of released sulphur by acid-insoluble metals. ► The acid-soluble ion-exchangeable metals are impotent in capturing sulphur, due to their quick release during coal pyrolysis.