Gasification performance of torrefied Timothy hay and spruce wood chars in a CO2 environment

AbstractTimothy hay abundantly available in New Brunswick, Canada, is mostly used for animal feed and bedding. Upgrading biomass using Torrefaction method can offer benefits in its waste management, energy density and energy conversion efficiency. Temperature and residence time play an important role in the torrefaction process. Meanwhile, CO2 gasification is also a promising thermochemical conversion process due to its potential to reduce net GHG emissions and tune syngas composition. This study investigates the impact of torrefaction parameters on isothermal and non‐isothermal CO2 gasification of Timothy hay and spruce chars. Timothy hay chars exhibited higher CO2 gasification reactivity than chars from spruce. The physicochemical properties analysis indicated that higher reactivity of Timothy hay char was mainly attributed to the high amount of alkali and alkaline earth metal (AAEM) content, relatively large BET surface area, a high number ofactive sites, and a low crystalline index. Moreover, in both experimental cases, char derived through a high heating rate and high residence time conditions exhibited improved gasification performance, which was attributed to the generation of large amounts of AAEM (Ca and K) and high specific surface area. Co‐gasification results during non‐isothermal processes under CO2 showed the presence of larger interactions in coal char/Timothy hay char blends than that of coal char/spruce char blends. For both experimental conditions, interactions were enhanced once the char prepared from high heating rate and high residence time was gasified with coal char. Thus, the proposed approach is a sustainable way of conversion of Timothy hay under CO2 environment.