A comparative study on extraction of methanol from lignin in electrolysis, fuel-cell and catalysis modes

Both the native lignin contained in biomass and the technical lignin that is a by-product of pulp and paper manufacture represent potential resources, and so efficient, low-cost valorization of lignin has attracted worldwide attention. The present work developed a means of extracting methanol from lignin in high yields under mild conditions and without an external power supply. This technology is based on the generation of numerous redox reaction sites by physically mixing powdered anode and cathode materials with an electrolyte, after which lignin and humidified air are supplied. Active oxygen species produced via water oxidation are proposed to attack the methoxy groups of the lignin to generate methanol. Optimization of the system provided a methanol yield of 73.4% at 75 °C and atmospheric pressure, exceeding the yields obtainable when operating in fuel-cell and electrolysis modes. This method can potentially be applied to the native lignin present in biomass, thus minimizing the environmental impact of methanol production.