Reforming of toluene as a tar model compound over straw char containing fly ash

Abstract

The present work focuses on confirming that straw char containing fly ash (SCFA) produced from steam–oxygen gasification (SOG) of straw pellets has the potential to be reused as a tar–reforming catalyst in the original process. The catalytic activity and reforming selectivity of SCFA was evaluated with toluene as a tar model compound in the presence of steam and hydrogen in a lab–scale fixed bed reactor at high temperature up to 900 °C. The kinetic results showed that SCFA was effective in toluene reforming with a complete toluene conversion at a space time of 0.05 kg h m−3 under 850 °C and a steam volume fraction of 15%. On the other hand, when hydrogen was present, the significant effect of hydrogen on toluene reforming was demonstrated by the formation of benzene through hydrodealkylation reaction. The volumetric ratio of H2O to H2 was an essential parameter that decided the selectivity of toluene reforming. Although the coexist of toluene and hydrogen would inhibit the gasification, SCFA was proved to be gasified during toluene reforming. The surface migration and agglomeration of inorganics due to gasification also resulted in the change of catalytic activity and reforming selectivity through time. In conclusion, this study demonstrated the potential utilization of SCFA derived from the SOG process as a tar–reforming catalyst to enhance the overall performance of the SOG process.