Reforming of lignin-derived tars over char-based catalyst using Py-GC/MS

Tar removal is one of the major challenges in implementation of biomass gasification technology. Syngas tars causes formation of aerosols and soots, which plug filters, reactors and fuel lines. In this study, a char-derived catalyst was tested in removal of tar produced from pyrolysis of kraft lignin in a pyroprobe reactor. The effects of reaction temperature (700, 800 and 900 °C), water amount (5-10 μl), pressure (0.1-2.2 MPa) and atmosphere (inert and hydrogen) on catalytic conditioning of tar components were assessed. The tar components were analyzed by GC/MS. Catechols were the most abundant tar components followed with phenols and guaiacols during non-catalytic kraft lignin pyrolysis. Results indicated that the char-based catalyst effectively decreased the contents of lignin tar. Reaction temperature, water loading and reaction pressure significantly affected the tar removal. An increase in reaction temperature led to an increase in removal efficiency of most tar components except naphthalene. Excessive water loading (10 μl) decreased the tar removal efficiency of char-based catalyst. High pressure promoted the catalytic conversion of lignin tar. Tar contents decreased significantly when hydrogen was used as a reaction medium and thus promoted the conversion of lignin into non-condensable gas.