Abstract
A lignin-rich feedstock, soda-anthraquinone spent pulping liquor, was pyrolyzed in a kiln reactor. The liquor was prepared from mixed northern hardwood chips at a liquor-to-wood ratio of 3.5 L/kg, 16% effective alkali, and an H-factor of 1000 h. The spent liquor was pyrolyzed at 500°C as is, after oxygen oxidation, and with addition of sodium formate to determine the effect on bio-oil yield and product distribution. Contrary to bio-oil from sawdust, a clear phase separation of the liquid product into an aqueous layer and a denser organic layer is obtained. The predominant products found in the organic layer collected after pyrolysis are phenols with varying degrees of methylation and ethylation. The organic yield appears to go through a maximum (32 wt% on spent liquor organics) at around 25 wt% formate added on spent liquor dry solids and subsequently decreases at greater charges. Oxidation of the spent liquor prior to pyrolysis appears to have a detrimental effect on the organic yield.
Published Version
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