Thermal conversion of black liquor solids to monomeric aromatic hydrocarbons based on synergistic catalysis by Na compounds and HZSM-5

Abstract

This work assessed the feasibility of producing aromatic hydrocarbons from catalytic pyrolysis of a black liquor solid (BLS) and the lignin extracted from the BLS (BLL). The results show that the addition of HZSM-5 could enhance the solid conversion for both BLS and BLL during the temperature-programmed pyrolysis process to produce more volatiles. Na compounds (Na₂CO₃ or NaOH) could promote the formation of H₂ and phenols in BLL pyrolysis, leading to generation of more monomeric aromatic hydrocarbons (MAHs) from the strengthened hydrodeoxygenation effect of HZSM-5. Synergistic effects on the release of volatiles were observed during BLL pyrolysis when applying Na₂CO₃ combined with HZSM-5. The yields of MAHs obtained from the synergistic catalytic pyrolysis of BLL and BLS increased from 0.95% to 25.83%, and from 1.09% to 25.5%, respectively. This study implies that combined application of active metal components and zeolites would be a promising pathway for facilitating MAH production from the pyrolysis of BLL or other biomass materials.