Cutting the Green Waste. Structure-Performance Relationship in Functionalized Carbon Xerogels for Hydrolysis of Cellobiose

摘要

The hydrolysis of cellulose and hemicelluloses in the presence of solid acid catalysts is of great importance as an entry process for the production of biofuels and chemicals. In this work, the effect of carbon surface chemistry on the catalyst conversion and selectivity in hydrolysis of cellobiose to glucose was studied. Solid catalysts based on carbon xerogels (CXs) containing various functionalities incorporating heteroatoms (S, P, N, O), as confirmed by XPS, TPD, ICP and EA analyses, were successfully prepared. CXs containing 3.4 wt % of phosphorus showed the best catalytic performance, reaching 90 % conversion of cellobiose with 72 % selectivity to glucose, under oxidative atmosphere and in a short reaction time of only 4 h. The presence of phosphonates (-P-C-) was found to increase the selectivity to glucose up to unprecedented 87 %. On the contrary, carbonyls, quinones, pyrydinic, pyrrolic and sulfonic groups were found to promote glucose degradation, leading to a final low yield of this product. Additionally, the increased concentration of oxygen in the reaction atmosphere was shown to significantly weaken the beta (1-4)-glycosidic bond, increasing the final yield of glucose.