Autothermal fast pyrolysis of waste biomass for wood adhesives

Biomass fast pyrolysis was performed in a bubbling fluidized bed reactor that incorporated two crucial innovations. A fractional condensation train provided dry bio-oils with only 1% of moisture and much reduced acidity. Autothermal pyrolysis with partial oxidation enhanced dry bio-oil quality while reducing the capital and operating costs by eliminating the need for external heating. Both endothermic pyrolysis with pure N₂ and autothermal pyrolysis with oxidant fluidization gases were carried out at 500 °C. Dry bio-oils of birch wood, birch bark or hydrolysis lignin, from both endothermic and autothermal pyrolysis, could substitute up to 65 % of phenol in reacting with formaldehyde to produce wood adhesives that met the international standard specifications on mechanical strength and formaldehyde emissions. Therefore, autothermal pyrolysis did not harm the bio-oil quality for phenol substitution. Dry bio-oil from autothermal pyrolysis of kraft lignin was able to replace 80 % of the phenol.