NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

TY - JOUR

T1 - NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

AU - Yue, Fen

AU - Pedersen, Christian Marcus

AU - Yan, Xiuyin

AU - Liu, Yequn

AU - Xiang, Danlei

AU - Ning, Caifang

AU - Wang, Yingxiong

AU - Qiao, Yan

PY - 2018

Y1 - 2018

N2 - Hydrothermal carbonization (HTC) is a valuable approach to convert furfural residue (FR) into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H–13C HSQC etc.) especially 1D selective gradient total correlation spectroscopy (TOCSY NMR) were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C) was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies.

AB - Hydrothermal carbonization (HTC) is a valuable approach to convert furfural residue (FR) into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques (1H and 13C NMR, 1H–1H COSY and 1H–13C HSQC etc.) especially 1D selective gradient total correlation spectroscopy (TOCSY NMR) were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions (180–240 °C at 8 h, and 1–24 h at 240 °C) was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies.

KW - Furfural residue

KW - Hydrothermal carbonization

KW - NMR

KW - Stock process water

U2 - 10.1016/j.gee.2017.08.006

DO - 10.1016/j.gee.2017.08.006

M3 - Journal article

AN - SCOPUS:85059644501

SN - 2096-2797

VL - 3

SP - 163

EP - 171

JO - Green Energy and Environment

JF - Green Energy and Environment

IS - 2

ER -