Search

The effect of hydrothermal conditions on enzymatic hydrolysis lignin (EHL) degradation in water-isopropyl alcohol co-solvent and optimal conditions were investigated. The yields and reactivity toward formaldehyde of degraded enzymatic hydrolysis lignin (DEL) were determined. The optimal conditions of temperature, time, and ratio of solids to liquids were 250 °C, 60 min, and 1:10 (w/v), respectively. The EHL and DEL were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (1H NMR), thermal gravity (TG), and differential scanning calorimetry (DSC) analyses. The results revealed that the molecular weight and polydispersity of DEL were lower than that of EHL. Although the fundamental structure of lignin before and after hydrothermal degradation was retained, the ether (β-O-4, α-O-4, etc.) content decreased, while that of hydroxyl (phenolic and aliphatic) increased. The DTGmax and Tg values shifted from 334 and 117 °C to 304 and 105 °C, respectively.

This study investigated the effect of oxygen plasma treatment on the glass transition temperature of enzymatic hydrolysis lignin (EHL) derived from the production of bio-ethanol. Differential scanning calorimetry (DSC) was used to obtain the glass transition temperature (Tg) of EHL. The results showed that the Tg value of EHL under different heating rates ranged from 160 to 200 °C, and there was a strong linear correlation between heating rate and Tg. The Tg value of oxygen plasma treated EHL decreased when compared with the untreated samples. The apparent Tg of the untreated sample was 168.2 °C, while the value of the treated sample was 161.5 °C. Distinct chain scission and introduction of oxygen-based functional groups on the surface of EHL were detected by XPS analysis. These changes may occur mainly on the bulky side chain and thus enhance molecular mobility of EHL. This indicates that oxygen plasma treatment can modify the structure and improve the reactivity of EHL efficiently.

This paper describes the investigation of the oxygen plasma treatment of enzymatic hydrolysis lignin (EHL) that was obtained from the lignocellulosic ethanol production pro- cesses. The application of EHL as a natural binder for biocomposite product manufacturing was in focus. To understand the effects of oxygen plasma treatment, the chemical changes on the surface of EHL were evaluated by Fourier transform infrared (FTIR) spectroscopy, X-ray photo-electron spectroscopy (XPS), and electron spin resonance (ESR) spectroscopy. Adding EHL into the cotton-stalk fiberboards has a beneficial effect on physical and mechanical properties. Moreover, adding oxygen plasma-treated EHL produced a 69.2% increase of internal bond strength (IB), a 78.2% increase of modulus of rupture (MOR), and a 49.8% reduction of thickness swelling (TS). The bonding improvement was probably due to the generation of more oxygen-related functional groups and free radicals on the surface of EHL after the oxygen plasma treatment. [ABSTRACT FROM AUTHOR]

• Lewis-acid Nb 2 O 5 was first applied in CFP of lignin. • High yield of AHs and selectivity to MAHs were achieved. • The formation of PAHs and char/coke can be limited. • Mechanism study was performed by model compound reaction and DFT method. Lewis-acid catalyst Nb 2 O 5 is first applied in catalytic fast pyrolysis (CFP) of enzymatic hydrolysis lignin (EHL) to produce aromatic hydrocarbons (AHs) that can be used as alternative liquid fuels. The catalyst exhibits a good talent to convert lignin into AHs with quite little polycyclic aromatic hydrocarbons (PAHs) formation. The yield of AHs reaches 11.2 wt% and monocyclic aromatic hydrocarbons (MAHs) takes up 94% under the optimized condition (Catalyst to Lignin ratio 9:1, 650 °C). No coke is generated during the reactions. The reaction sequence is proposed and verified by model compound reactions. Furthermore, DFT calculations are performed to understand the mechanisms of limitation of PAHs or char/coke formation and the efficient deoxygenation ability over catalyst. Nb 2 O 5 with Lewis acid sites is proved to be a promising catalyst for the production of AHs from lignin. This work provides a new idea on choice of catalysts for CFP of lignin in future. [ABSTRACT FROM AUTHOR]