Evolution Process of Humins Derived from Glucose

The evolution process of humins derived from glucose was studied dynamically from the feedstock, the intermediates in solution, till humins solid formed. The key intermediates resulting in the formation of humins were identified, unveiling two elementary reactions including etherification of dehydrated glucose and electrophilic substitution of furfuryl alcohol (FAL). The characteristic IR peaks at 1583 and 1616 cm(-1) could be attributed to the C=C conjugated with C=C and the C=C conjugated with C=O, respectively, whereas the shift from 1583 to 1616 cm(-1) could be promoted by O-2 or adding kojic acid. Unexpectedly, the participations of HMF and small aliphatic acids were excluded. Herein, through characterizations such as HPLC-MS/MS, IR and SEM, the structural models of glucose-derived humins at different temperatures and a successive growth diagram were proposed.

Automated summary

This study dynamically investigated the evolution process of humins derived from glucose, from feedstock to solid form. The key intermediates involved in humins formation were identified as etherification of dehydrated glucose and electrophilic substitution of furfuryl alcohol (FAL). Infrared spectroscopy analysis showed that specific peaks corresponded to specific structures, and the shift of peaks could be induced by oxygen or kojic acid. Structural models of glucose-derived humins at different temperatures and a successive growth diagram were proposed through various characterization techniques.