Effects of Na and Ca on gaseous products evolution behaviors for Fe catalyzed lignite pyrolysis volatiles reforming

In this work, Fe-Na/Char and Fe-Ca/Char catalysts were synthesized to improve H2 and CO yields from coal pyrolysis volatiles reforming. Meanwhile, the gas evolution behavior of water and organic matter in the volatiles during the reforming process was investigated. Fe/Char promoted the cleavage of water released from lignite to H2, and the intensity of H2 evolution peaks increased at 120–380 °C, and Fe was oxidized (H2O + Fe0→H2 + FexOy). Fe/Char promoted the cleavage of aliphatic side chains from the pyrolysis of coal at 400–650 °C to produce H2. The H2 yield increased from 129.92 mL/g (coalad) to 182.17 mL/g (3.6Fe/Char) at the reforming temperature of 600 °C. Na and Ca promoted the cleavage of C-H and oxygen-containing functional groups (C-O and C=O) by the Fe catalysts, and the intensity of the H2 peaks enhanced at 400–650 °C. Meanwhile, Na facilitated the carburization of Fe to form Fe3C and further promoted the cracking of water for H2 and CO production. The formation of Ca2Fe2O5 from Ca and Fe2O3 promoted the reforming of CH4 and CO2 to H2 and CO. The 3.6Fe-0.8Na/Char and 3.6Fe-1.2Ca/Char increased the H2 yield by 1.51 and 1.38 times at the reforming temperature of 750 °C, respectively.