Valorization of Lignin by Partial Wet Oxidation Using Sustainable Heteropoly Acid Catalysts
Abayneh Getachew Demesa,
Arto Laari,
Mika Sillanpää,
Tuomas Koiranen
Affiliations
Abayneh Getachew Demesa
Laboratory of Process and Product Development, LUT School of Engineering Science, Lappeenranta University of Technology, Skinnarilankatu 34, FI-53850 Lappeenranta, Finland
Arto Laari
Laboratory of Process and Product Development, LUT School of Engineering Science, Lappeenranta University of Technology, Skinnarilankatu 34, FI-53850 Lappeenranta, Finland
Mika Sillanpää
Laboratory of Green Chemistry, LUT School of Engineering Science, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland
Tuomas Koiranen
Laboratory of Process and Product Development, LUT School of Engineering Science, Lappeenranta University of Technology, Skinnarilankatu 34, FI-53850 Lappeenranta, Finland
The production of carboxylic acids by partial wet oxidation of alkali lignin at elevated temperatures and pressures was studied experimentally. Two different heteropoly acids, phosphotungstic acid (H3PW12O40) and phosphomolybdic acid (H3PMo12O40), were used to catalyze the oxidation of lignin under hydrothermal conditions. Factors influencing the total yield of carboxylic acids formed during the partial oxidation of lignin were investigated. Formic, acetic and succinic acids were the major products identified. Of the two catalysts used, phosphomolybdic acid gave the most promising results, with carboxylic acid yields and lignin conversions of up to 45% and 95%, respectively.
