Investigation on the steam gasification mechanism of different chars using isotopic tracing method

Gasification can provide syn-gas for consequent chemical production from carbon resources. The control of CO2 emission produced from gasification calls for the lower temperature and the more biomass char for the feed compared with traditional gasification, and the mechanism for steam gasification of different chars is more important. The gasification behaviors of four biomass chars and four coal chars are studied. The mechanism is probed using H216O/H218O period step tracing method coupled with various solid-state analyses on char structures. The increment of intermediates with increasing conversion demonstrate other slow step exists during gasification, and the solid state spectra of chars after and before gasification demonstrates that the condensation of polyaromatic clusters in chars occurs accompanied with gasification. The addition reactions of radicals generated from gasifying agents and unsaturated carbon bonds C = C in chars is the slower step during gasification and enhancing the addition of radicals to unsaturated C = C bonds may be helpful for the higher gasification rate.