Investigation of the synergistic mechanism during biomass and coal gangue co-gasification
Biomass is a sustainable green coal alternative, and its thermochemical conversion, particularly hydrogen-rich gasification, offers an effective pathway for high-value utilization. Co-gasification of biomass with coal gangue enables synergistic utilization of carbon resources, with significant potential for emission reduction and efficiency enhancement. To elucidate how typical biomass components govern the gasification process, three feedstocks with distinct dominant characteristics were selected: pine stick (high cellulose), soybean straw (high nitrogen), and corn stover (high ash with abundant K+). Under fixed conditions (850 °C, steam flow 2 mL/min, N2 flow 75 mL/min), co-gasification with coal gangue was investigated. Results indicated that compositional differences led to distinct synergistic patterns and product distributions. All systems achieved the highest hydrogen yield at a 5:5 raw material mass ratio. The high-cellulose pine stick system yielded the most H2 (9.06 mmol/g) and H2+CO yield (15.25 mmol/g), exhibiting a 'three high, three low' advantage due to efficient volatile reforming. In contrast, the high-ash/K+ corn stover system showed the strongest synergy for CO (SI = 1.22), promoted by the catalytic Boudouard reaction. The high-nitrogen soybean straw system achieved an optimal H2/CO ratio (2.00) but suffered from suppressed syngas yield due to inhibitory nitrogenous tars. This study confirms that biomass composition—specifically cellulose, ash/K+, and nitrogen content—differentially regulates syngas production and synergy by steering dominant reaction pathways, providing a theoretical basis for targeted conversion of waste resources.