Mechanism study on arabinose pyrolysis by combining TG-FTIR-GC-MS and theoretical calculations

In this study, arabinose was selected as the model compound of hemicellulose. The pyrolysis experiments were conducted by combined thermogravimetry-Fourier infrared spectroscopy-gas chromatography-mass spectrometry (TG-FTIR-GC-MS) technique. The evolution of functional groups was observed. Experimental results indicated that the main gas products were H 2 O, CO 2 , and CH 4 . And volatiles also contained many furan derivatives, sugar derivatives, aromatic hydrocarbon derivatives, and other trace products. In addition, the quantum chemistry calculations were utilized to reveal the formation mechanisms and pathways of the significant products from arabinose pyrolysis. Initially, arabinose prefers to undergo a ring-opening reaction to form acyclic D-arabinose with the activation energy of 177.6 kJ/mol, which is the primary source of each product. Furfural (PD) is the most abundant furan derivative. The ring-condensation reaction first of arabinose and the isomerization reaction first of D-arabinose are the favorable paths to form it in terms of energy. The C1-C2 bond scission of D-arabinose is more favorable to form furan (PA) and formic acid. The dehydration mechanism first of arabinose is the dominant path to generate 2,7dioxabicyclo[2.2.1]heptan-5-one (PE). The formation of acetic acid (PB) is kinetically and thermodynamically favorable. Once it is formed, it is easy to decompose into CO 2 and CH 4 . The formation of 2(5H)furanone (PC) is restricted by the decarboxylation reaction of D-arabinose, which has a high energy barrier of 384.8 kJ/mol. To conclude, a deep understanding of the pyrolysis mechanism of arabinose could be obtained through the combination of experiments and quantum chemistry calculations. (c) 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.