Understanding the enhanced preparation of aromatic hydrocarbons in pyrolysis of individual lignocellulosic biomass components over a (Ca-Fe)/HZSM-5 catalyst

Limited knowledge regarding the controlled preparation of aromatic hydrocarbons (AHs) via catalytic pyrolysis of individual organic components hinders high yields of lignocellulosic biomass-based AHs. This report describes a systematic investigation of AHs generation following catalytic pyrolysis of organic components referring to cellulose, xylan, and lignin. Results show that in a programmed-heating process (20 °C/min), a (Ca-Fe)/HZSM-5 catalyst promoted the degradation of cellulose, xylan, and lignin with respective increment ratios of 24.56 %, 17.29 % and 19.45 %, and significantly increased the release of benzene during the pyrolysis of cellulose and xylan. In a fast-heating process (20 °C/ms), Ca-Fe alone presented a positive effect on bio-oil yield from cellulose, whereas HZSM-5 and (Ca-Fe)/HZSM-5 afforded high bio-oil yields from all three components. Notably, Ca-Fe and HZSM-5 exhibited synergistic effects on the bio-oil and AHs yields following cellulose pyrolysis, and on AHs yield following xylan pyrolysis. Alcohols, aldehydes, and furans were suitable precursors for generating AHs via pyrolysis of both cellulose and xylan. Lignin conversion to AHs involved various potential reaction pathways, including dehydration-deoxygenation-aromatization and dehydration-hydrodeoxygenation. The orders of (Ca-Fe)/HZSM-5 catalyzed pyrolysis of individual components towards AHs generation were xylan > cellulose > lignin. The presence of Ca-Fe particles inhibited deactivation of HZSM-5 in pyrolysis of a cellulose/xylan/lignin mixture.