Improving the Fractionated Catalytic Oxidation of Lignocellulosic Biomass to Formic Acid and Cellulose by Using Design of Experiments

The main objective of this contribution was to optimize the process conditions for a fractionated oxidation of lignocellulosic biomass (e.g., wood) to produce formic acid and cellulose for further applications. Using the Lindqvist-type polyoxometalate K5V3W3O19 as a homogeneous catalyst in aqueous media, we were able to selectively oxidize the hemicellulose and lignin fractions. While hemicellulose and lignin are converted to formic acid, the cellulose fraction remains untapped. Furthermore, we optimized the process conditions with the help of a Box-Behnken design of experiments. Thereby improved conditions showed an output of formic acid from lignin three times higher compared with the initial parameters. Furthermore, recycling of the catalyst has been carried out successfully without observing significant changes in vanadium species. Finally, we investigated the conversion of different real biomasses (hardwood, softwood, and algae) leading to new structure-performance relationships.