Synergistic effects of Fe-loading on pyrolysis characteristics of cellulose, xylan, and lignin: TG, TG-MS, and Py-GC/MS analysis

This study systematically investigates the effects of Fe-loading on the pyrolysis behavior of three key biomass components: cellulose , xylan , and lignin . Complementary analytical techniques, thermogravimetric analysis (TGA), thermogravimetry-mass spectrometry (TG-MS), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), were utilized to assess the impact of Fe-loading on: ( i ) pyrolysis characteristics, ( ii ) the combined pyrolysis index ( CPI ), ( iii ) small-molecule gas evolution, and ( iv ) tar product distribution. Results demonstrate that the loading of Fe(NO 3 ) 3 significantly reduced the initial pyrolysis temperatures of cellulose and xylan by ∼140 °C and ∼62 °C, respectively, resulting in 58 % and 37 % decreases in CPI values. Conversely, lignin exhibited a 111 % CPI increase under Fe loading conditions, attributable to accelerated aryl-ether bond cleavage. The presence of Fe enhanced CO 2 evolution while suppressing H 2 O and CO generation in cellulose / xylan conditions. In contrast, it promoted CH 4 , H 2 , CO, and CO 2 evolution during lignin pyrolysis. Py-GC/MS analysis indicated that the presence of Fe drives aromatization through deoxygenation pathways while inhibiting ring-opening depolymerization, consequently shifting tar composition toward higher-carbon-number aromatic hydrocarbons. The findings can serve as a valuable reference for the application and promotion of the high-value valorization of waste biomass.