The project “Innovationsraum: Bioball – GlyChem – Glykane und Koppelprodukte als biogene Wertstoffe” (Part B) was carried out by the Department of Technical Chemistry II at the Technical University of Darmstadt, specifically within the Institute IWAR – FG Stoffstrommanagement and Resource Economics. The research period ran from 1 May 2020 to 30 April 2023 and was funded under the German Federal Ministry of Education and Research grant number 031B0905B. The aim was to develop a mechanocatalytic partial depolymerization route that converts lignocellulosic feedstocks such as cellulose, chitin, and mixed lignocellulose into water‑soluble glycans with a molecular weight between 1 and 10 kDa, which can subsequently be aminated to serve as hardeners for bio‑based epoxy resins. Residual solids from the glycan extraction were further processed by ethanol ageing to produce carboxylic acids as coupling products.

The technical work focused on optimizing the mechanocatalytic reaction conditions. Four acids were initially screened: inorganic sulfuric and phosphoric acids, and organic oxalic and acetic acids. Under identical reaction parameters, sulfuric acid yielded a fully soluble glycan fraction (up to 100 %) whereas phosphoric acid produced only 12 % soluble product. X‑ray diffraction revealed that milling amorphized the partially crystalline cellulose, enhancing macromolecular accessibility. Thermogravimetric analysis showed weight loss above 100 °C, prompting the design of milling cycles that kept the temperature below 90 °C to avoid unwanted side reactions. High‑field HSQC NMR of glucose‑derived products confirmed polymerization into β‑1,4 and β‑1,6 glycosidic linkages, effectively suppressing monosaccharide formation.

Acid concentration was a critical parameter; a 3 % sulfuric acid solution provided the highest yield while minimizing monosaccharide by‑products. Milling at 500 rpm with 20 % fill using zirconia balls produced a sharp increase in glycan content after 15 min for both 3 % and 6 % acid concentrations, attributed to the formation of soluble oligomers. After 45 min the glucose concentration stabilized at roughly 2.5 %, indicating a balance between polymerization and depolymerization, and the oligomer molecular weight remained within the target 1–10 kDa window. Comparative studies of milling ball materials (zirconia, stainless steel, tungsten carbide) demonstrated that higher‑density balls increased the soluble fraction, though they also generated more heat. Varying ball diameter between 2 mm and 4 mm revealed that larger balls, despite fewer collisions at a given rotation speed, delivered higher reaction probabilities due to their greater mass; at 430 rpm this configuration yielded the highest product output.

The project’s outcomes were disseminated through several peer‑reviewed publications, including a 2022 Chemie Ingenieur Technik conference abstract, a 2023 preprint on ChemRxiv, and a 2023 article in Sustainable Energy & Fuels reporting the mechanocatalytic process and its performance metrics. A doctoral dissertation by the lead researcher was also published by TU Darmstadt in 2023. Presentations at European and international conferences, such as the 13th European Congress of Chemical Engineering and the 5th International Symposium on Green Chemistry, highlighted the method’s scalability and potential industrial relevance. No competing technologies from other institutions were reported during the project period. The work therefore advances the technology readiness level of mechanocatalytic glycan production, positioning it as a viable route for converting renewable lignocellulosic biomass into high‑value biobased materials.