Synergistic effect of torrefaction and gasification temperatures on hydrogen-rich syngas quality from steam gasification of cornstalk-derived biochar

• Cornstalk-derived biochar was employed to produce hydrogen-rich gasification syngas . • Synergistic effect of torrefaction and gasification temperatures was investigated. • Torrefaction of cornstalk can regulate the gasification temperature for more H2. • Loss on gas yield and carbon conversion rate was proved by excessive torrefaction. • Enhanced carbonization of cornstalk inhibits tar formation during steam gasification . Steam gasification of cornstalk and torrefied biochar was conducted in a fixed bed chamber to investigate the quantitative and qualitative characteristics of hydrogen-rich syngas. Emphasis was placed on H 2 and CO production, considering the varied temperatures of torrefaction and gasification and their synergetic effects. The study reports the production of syngas and tar, along with calculations of calorific value and carbon conversion rate. Experimental results indicated that the H 2 content, syngas production, and carbon conversion rate from cornstalk gasification improved with increasing reaction temperature. The carbonization level of cornstalk through torrefaction pretreatment was examined. Subsequently, the analysis of syngas composition from torrefied biochar gasification revealed that the maximum H 2 content was identified at the highest torrefaction temperature (290 °C), not the highest gasification temperature (950 °C). Conversely, the maximum production of syngas and carbon conversion rate were obtained at the highest gasification temperature, not the highest torrefaction temperature. Furthermore, the calorific value of syngas decreased with lower CH 4 + C x H y content under higher torrefaction and gasification temperatures. In conclusion, achieving a balance between H 2 content and gas production can be facilitated by considering torrefaction pretreatment in the steam gasification process.