AbstractThe co-gasification behaviors of composite samples of biomass and lean coal were investigated under a CO2 atmosphere. The composite behaviors were determined based on thermogravimetric analysis and the Coats-Redfern method. These methods were used to analyze the kinetics of the processes. The results showed that the temperature ranges of the lean coal, biomasses, and the gasification ability of each biomass were different, and the coordination effects of each biomass varied. The addition of alkali metals had little influence on the pyrolysis efficiency and the peak temperature of composite samples of soybean stalk and lean coal, but it did promote gasification. In the processes of pyrolysis and gasification, composite samples of soybean stalk and lean coal exhibited lower activation energies than unmixed samples, but there was no significant enhancement with the extra alkali metal.