Gas-Phase Partial Oxidation of Lignin to Carboxylic Acids over Vanadium Pyrophosphate and Aluminum-Vanadium-Molybdenum

Lignin is a complex polymer that is a potential feedstock for aromatic compounds and carboxylic acids by cleaving the -O-4 and 5-5 linkages. In this work, a syringe pump atomizes an alkaline solution of lignin into a catalytic fluidized bed operating above 600K. The vanadium heterogeneous catalysts convert all the lignin into carboxylic acids (up to 25% selectivity), coke, carbon oxides, and hydrogen. Aluminum-vanadium-molybdenum mostly produced lactic acid (together with formic acid, acrylic acid, and maleic anhydride), whereas the vanadium pyrophosphate catalyst produced more maleic anhydride.