Catalytic oxidation of lignin to dicarboxylic acid over the CuFeS2 nanoparticle catalyst

CuFeS2 nanoparticles have been synthesized and used as catalyst for the degradation of lignin. Under mild condition of reaction at 60 degrees C and 5 h in the presence of 2 ml hydrogen peroxide, lignin can be degraded completely and converted to dicarboxylic acids, such as oxalic acid (OA), fumaric acid, maleic acid, and succinic acid (SA), carbon oxides, and aromatic compounds. The major product is OA (up to 30% selectivity) and SA. On the basis of the chemicals detected, we proposed a logical mechanism similar to Fenton reaction. The results reveal that HO center dot and HOO-, formed from the cleavage of hydrogen peroxide over the catalyst, play an essential role in the oxidation of lignin to destroy its aromatic structure and generate carboxylic or DCA. This is a potential method to convert native lignin as a renewable feedstock to produce valuable chemicals.