Effects of methane and steam on syngas and tar from biomass catalytic gasification

This experimental study was conducted on the addition of methane and steam to biomass gasification in a two-stage reactor, taking pine wood as material. The effects of the methane on biomass ratio, α, and the steam to carbon ratio, S/C, on gas yield, carbon conversion, tar yield, tar composition and dew point were explored. The results showed the yield of H2 increased by 57.4% as α changed from 0 to 0.4, so the addition of methane could be beneficial to the generation of hydrogen-rich syngas. The tar yield decreased by 30.5% and the yield of second and fifth classes of tars reached a minimum when α was 0.2. It was found that appropriate amounts of CH4 can promote the conversion of tar, especially the conversion of macromolecule tar and phenols. With the increase of S/C, the yield of H2 increased and the CO yield decreased. The content of all classes of tars decreased as S/C increased from 1 to 1.5. However, when the S/C was further increased to 2, the second and fifth classes of tars increased, indicating that steam can promote the conversion of tar to syngas, but excessive steam inhibits the decomposition of phenols and macromolecular tars. Both methane and steam in moderation can increase the H2 yield of syngas, reduce the tar yield, improve the quality of the syngas, and aid the further utilization of the gasification products. © 2019, Chemical Industry Press. All right reserved.