BIORESOURCE TECHNOLOGY
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2021
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IF 9.642
Yue Han,Chao Liu,Xiangchen Kong,Xing Wang,Yuyang Fan,Ming Lei,Ming Li,Rui Xiao,Longlong Ma
In this study, two counterexamples of lignin preoxidation-hydroconversion were reported. First, two lignin feedstocks were preoxidized with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in acetonitrile with various dosages (15%, 30%, and 60%). Then, these preoxidized lignins (HELOs and MWLOs) were hydroconverted in supercritical ethanol catalyzed by Cu/CuMgAlO x . Total yields from HELOs were all higher than those from HEL , indicating the good promotion of DDQ preoxidation on the subsequent hydroconversion of HELOs, especially with the DDQ dosage of 15%. Differently, the promotion effect of DDQ preoxidation on the hydroconversion of MWLOs depended on the DDQ dosage as well as the reaction time. Through the comparison of two counterexamples, this work bursted the myth that preoxidation can always promote the subsequent hydroconversion of lignin, revealed the influence of lignin property, preoxidation degree, and reaction conditions on the subsequent hydroconversion of preoxidized lignin, and presented the new insight into the preoxidation-hydroconversion strategy for lignin.
研究领域:
化学工程
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催化
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木质素化学
✓ 已验证
DOI
PubMed
高影响因子
FUEL PROCESSING TECHNOLOGY
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2021
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IF 7.033
Xiangchen Kong,Chao Liu,Weicong Xu,Yue Han,Yuyang Fan,Ming Lei,Ming Li,Rui Xiao
Stubborn lignin (SL) is the thermochemically stable fragment generated from biomass utilization (e.g., pyrolysis , hydrolysis, fermentation, pulping), which is comparatively difficult to be further depolymerized into value-added bio-products. The cleavage of the stubborn linkages within the structure of SL, such as C C, α -O-4, and 4-O-5 linkages, is the key for its valorization. Herein, we investigated the depolymerization of SL through catalytic hydroprocessing in supercritical methanol with Cu/CuMgAlO x catalyst. The yield of monomers reached 37.76C% with 240 min at 300 °C. Cyclohexanols were identified as the major monomeric products, indicating the occurrence of hydrodeoxygenation and hydrogenation. GPC , quantitative 13 C NMR, HSQC NMR, and HMBC NMR analyses evidenced the depolymerization of SL and upgrading of its derivatives. Furthermore, the mechanistic studies were carried out to provide insights to the stubborn linkage cleavages. The degrees of difficulty to break up the three involved linkages obeyed the sequence of β -5 > 4-O-5 > α -O-4. The apparent activating energies ( E a ), chemisorption energies ( E c ), and bond dissociation energies (BDE) were determined computationally to support the experimental results from the perspectives of kinetics, chemisorption, and thermodynamics, respectively. This research provides a reliable way for the utilization of SL.
研究领域:
化学工程
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催化
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生物化学
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可再生能源
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2020
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IF 3.421
Xiangchen Kong,Chao Liu,Yue Han,Ming Lei,Yuyang Fan,Ming Li,Rui Xiao
The development of an economic and sustainable catalytic system was crucial for lignin-based biorefinery. Herein, we reported a low-cost Cu/CuMgAlOx catalyst with promising activity toward lignin hydrodeoxygenation (HDO) through a H2-free method. Supercritical methanol was used as the hydrogen donor, solvent, and reactant simultaneously. Guaiacol was employed as a representative lignin model compound to reveal the HDO mechanism of lignin derivatives. HDOs of guaiacol performed at 250, 275, 300, and 350 °C with durations ranging from 15 to 120 min indicated a high HDO efficiency of the catalytic system. The obtained liquid products were categorized to oxygen-containing unsaturated products (OUPs), oxygen-containing saturated products (OSPs), and cycloalkanes. A kinetic model based on a simplified reaction process containing the three following conversion steps was established: guaiacol transformed to OUPs through the initial HDO, then hydrogenated to OSPs (medium HDO), and eventually turned to cycloalkanes by the deep HDO. The deep HDO was the rate-determining step, and the apparent activation energies of the three steps were all lower than those in the literature. Phenol, 1,2-cyclohexanediol, anisole, and veratrole were the major intermediates, the HDOs of which were programed for pathway verification. Remarkably, catechol (the culprit of condensation) was not produced in this system. Overall, a detailed reaction network of guaiacol HDO was established, and the veil of Cu/CuMgAlOx-catalyzed lignin-derivatives HDO in supercritical methanol was revealed. This work paved the way for the application of Cu/CuMgAlOx catalyst in lignin-derivatives upgrading.
研究领域:
化学工程
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催化
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生化工程
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可再生能源
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）