In the past century, petroleum became the primary feedstock for the industrial production of organic chemicals. The use of fossil raw materials is nowadays questionable due to the increasing environmental awareness in society and the guiding principle of “sustainable development” to which the chemical industry commits itself. Biomass seems to be a promising alternative as renewable and sustainable source for fuels and chemicals. Furthermore, organic electrosynthesis is an ecological and powerful approach. Kraft lignin is a waste product from the dominating Kraft pulping process for cellulose production. The polyphenolic structure qualifies it as potential sustainable feedstock for aromatic fine chemicals. Due to the inertness and degradation robustness of the Kraft lignin it is currently only incinerated for energy recovery. We investigated an electrochemical method for the highly selective production of the aromatic fine chemical vanillin form Kraft lignin. Thereby, the anodic degradation takes place at activated Ni/P-foam electrodes and the electrolysis was optimized for temperatures below 100 °C. Moreover, we present an easy protocol for adsorption and selective desorption of low weight phenolic compounds from black liquor (waste stream from the Kraft pulping process). Employing ion exchange resins gave rise to a selective removal of low molecular weight phenols from the strongly alkaline electrolyte without acidification and precipitation of remaining lignin. The depleted black liquor was also electrochemically treated to breakdown the containing lignin and to maximize the yield of vanillin.

Electrochemical conversion of Kraft-lignin to valuable products

255th National Meeting (2018)

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