Insight into the Formation of Anhydrosugars in Glucose Pyrolysis: A Joint Computational and Experimental Investigation

5 years ago

Insight into the Formation of Anhydrosugars in Glucose Pyrolysis: A Joint Computational and Experimental Investigation

Min-shu Cui, Xiao-chen Dong, Yong-ping Yang, Qiang Lu, Bin Hu, Xiao-yan Jiang, Chang-qing Dong

Fast pyrolysis of glucose/cellulose will produce abundant 1,6-anhydro-β-d-glucopyranose (known as levoglucosan, LG) as the predominant anhydrosugar product, together with certain amounts of other anhydrosugars, mainly including 1,6-anhydro-β-d-glucofuranose (AGF), 1,4:3,6-dianhydro-α-d-glucopyranose (DGP), 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (APP), 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC). The formation mechanisms of the latter four anhydrosugar products are not well-known at present. Substantiated by analytical pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) experiments, quantum chemistry calculations are employed to give a deep insight into their formation mechanisms in this study. The anomeric effect of glucopyranose has a distinct effect to their formation. DGP is mainly derived from α-d-glucopyranose which plays a vital role in the formation of 1,4-acetal ring. On the contrary, APP and LAC can merely derive from β-d-glucopyranose due to the dehydration at 1-OH + 2-H site. APP is important but not necessary to form LAC, and their formation pathways also compete with each other. Moreover, AGF is not influenced by the anomeric effect of the two anomers, because its formation relies on the acyclic d-glucose.

Publisher URL: http://dx.doi.org/10.1021/acs.energyfuels.7b01250

DOI: 10.1021/acs.energyfuels.7b01250