Mechanocatalytic depolymerization of cellulose and raw biomass and downstream processing of the products

• Molecular understanding of mechanocatalysis for the depolymerization of cellulose.
• ‘Deep’ depolymerization of cellulose to water-soluble oligosaccharides.
• Downstream processing of ‘water soluble lignocellulose’ in the high-yield production of furfural and sugar alcohols.

The utilization of lignocelluloses (e.g. wood, grass, crops residues and several others) shows great potential as part of the solution for decreasing the dependence of modern societies on fossil resources. In spite of this, the catalytic conversion of these renewable carbon resources via chemical and biotechnological processes is hindered by their complex polymeric nature. For this reason, chemical or enzymatic processes for hydrolysis of cellulose suffer from low efficacy due to harsh reaction conditions and high byproduct formation in case of the chemical methods, or high costs and long reaction times for the enzymatic methods. There is thus an urgent need for processes able to convert the whole plant biomass, which allow the formation of fermentable sugars and technical sulfur-free lignins. Recently, we demonstrated the combination of acid-catalysis with mechanical forces to be an efficient approach to fully overcome the recalcitrance of lignocellulose. As a result, the solvent-free depolymerization of lignocellulose (in solid-state) forms ‘water-soluble lignocellulose’ in quantitative yield. In this article, we present an overview of the mechanocatalytic depolymerization of lignocellulose and downstream processing of the ‘water-soluble’ lignocellulose’ to sugar alcohols and furfurals. The water-soluble products appear to be the ideal platform at the beginning of advanced value chains of biorefining, starting with ‘real’ lignocellulosic substrates.

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