Continuous Steam-Assisted Low-Temperature Pyrolysis of Alkali Lignin and Selective Production of Guaiacol Components in a Fixed-Bed Reactor

Alkali lignin, which is derived from the pulping and paper-making process, has been recognized to have great potential in the preparation of chemicals and value-added renewable biofuels. In this report, saturated steam was applied simultaneously, a novelty procedure, to assist in lower-temperature pyrolysis (from 275 to 350 °C) of alkali lignin and selective production of guaiacol components in a fixed-bed reactor. The results indicated that the lower-temperature pyrolysis displayed a positive effect on the breaking of aliphatic C–O bonds of lignin (β-O-4 bond) and helped to increase the intensity of oxygenated aromatic carbons and aromatic C═C structures. The guaiacol components were successfully removed from alkali lignin and extracted by saturated steam. This method displayed a useful effect on pyrolysis of lignin and on higher selectivity of guaiacol components. A relatively higher yield of stable solid carbon (from 68.45 to 88.67 wt %) and relative selectivity of guaiacol components (from 79 to 90.7%) were obtained. This novel method is quite a promising technique for simultaneous pretreatment of lignin and selective production of guaiacol components.