Structural characterization and pyrolysis behavior of humin by-products from the acid-catalyzed conversion of C6 and C5 carbohydrates

摘要

Humin, a solid by-product formed during the acid-catalyzed conversion of carbohydrate to platform chemicals, can be further utilized by pyrolysis technology. In this study, two humins derived from glucose (humin-g) and xylose (humin-x) were characterized by elemental analysis, FTIR and C-13 NMR. Both humins were polymers rich in furan rings, and their carbon contents were more than 66%. Thermogravimetry and pyrolysis kinetic analyses based on Flynn-Wall-Ozawa and Friedman methods suggested that the activation energies for both humins increased as their conversion rates increased. At low conversion rates, the activation energy of humin-x was higher than that of humin-g, but this was reversed at high conversion rates. The results suggest that humin-g has better thermal stability following the removal of weak linkages at low temperature. Finally, Py-GC/MS was employed to study the product distribution from humin pyrolysis. The mechanisms for formation of typical products and the influence of temperature on product distribution are discussed. (C) 2016 Elsevier B.V. All rights reserved.