Energy & Environmental Science
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2013
·Vol. 6
·期 3
·994-1007
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IF 11.653
Qi Song,Feng Wang,Jiaying Cai,Yehong Wang,Junjie Zhang,Weiqiang Yu,Jie Xu
Valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts has been studied. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Alcohols, such as methanol, ethanol and ethylene glycol, are suitable solvents for lignin conversion. Analyses with MALDI-TOF and NMR show that birch lignin is first fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. The presence of gaseous H2 has no effect on lignin conversion, indicating that alcohols provide active hydrogen species, which is further confirmed by isotopic tracing experiments. Catalysts are recycled by magnetic separation and can be reused four times without losing activity. The mechanistic insights from this work could be helpful in understanding native lignin conversion and the formation of monomeric phenolics via reductive depolymerization.
研究领域:
生物化学
·
催化化学
✓ 已验证
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
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2016
·
IF 3.847
Chao Zhou,Xiangdong Zhu,Feng Qian,Wei Shen,Hualong Xu,Shicheng Zhang,Jianmin Chen
This work investigated the yields of monomeric phenols in bio-oil derived from hydrothermal liquefaction of rice straw (RS) in water and ethanol mixtures using a reductive CuZnAl catalyst. Based on the results of an initial analysis, five monomeric phenolic compounds were selected for research due to their higher concentrations, namely phenol, 4-ethyl-phenol, 2-methoxy-phenol, 2-methoxy-4-ethyl-phenol and 2,6-dimethoxy-phenol. The optimized conditions for the production of monomeric phenols can be determined as: 2 g of CuZnAl catalyst, a ratio of 50% ethanol/50% water (v/v), a temperature of 300 °C and a reaction time of 30 min. Results suggested that the maximum yield of total monomeric phenols could reach as high as ~ 26.8% (based on the mass of RS lignin), and that the aqueous phase yielded 95.5% of the monomeric phenols due to the solubilization of the ethanol. The CuZnAl catalyst was recycled five times, and a slight loss in activity was observed and examined using a number of technologies, including inductively coupled plasma , X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray detection. The low-cost nature of the CuZnAl catalyst makes it an ideal catalyst for the enhancement of monomeric phenols yields in water and ethanol mixtures.
研究领域:
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
FUEL
·
2024
·
IF 6.7
Zhaozhuo Yu,Wenzhuo Kong,Yaping Guo,Wen Liang,Jiawei Liang,Meijuan Chen,Dongxu Zhao,Hongzhen Ma,Xiangjun Liu,Solomon Inalegwu Okopi,Lei Che,Qi Zhang,Zhuohua Sun,Fuqing Xu
Eco-friendly lignin depolymerization into monomeric phenols in an aqueous system is essential for the sustainable and green valorization of lignocellulosic biomass. However, a major challenge in this process is the development of efficient and stable catalysts for aqueous reductive catalytic fractionation (RCF), as water can cause catalyst deactivation and reduce monomer yields. In this study, a water-resistant RuNiZnO x /Nb 2 O 5 catalyst is developed that demonstrates excellent catalytic activity and stability in aqueous systems, achieving a near-theoretical monomeric phenol yield of 40.1 wt% under reaction conditions of 240℃ and 3 MPa H 2 for 4 h. The excellent performance of this catalyst is attributed to the synergistic hydrogen spillover effect between Ni and Ru and the strong acidic properties of ZnO, as revealed by in-situ XPS analysis and NH 3 -TPD, respectively. This hydrogen spillover effect significantly alters the product composition, promoting the generation of POH-S/G from lignin model compounds. Additionally, screening of the catalyst support materials revealed that Nb 2 O 5 not only enhances Ru dispersion but also improves its stability, resulting in a minor decrease in lignin monomer yield observed after three cycles.
研究领域:
生物质化学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
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2020
·
IF 3.421
Jun Hu,Mingxing Zhao,Bingxing Jiang,Shiliang Wu,Ping Lu
Direct hydrogenolysis of native lignin in biomass into monomeric phenols has received increasing attention. In this work, catalytic transfer hydrogenolysis of native lignin from birch, pine, and corn stalk was studied over a Ni–Pd bimetallic catalyst using isopropanol as the in situ hydrogen source. The bimetallic Ni50Pd50/SBA-15 exhibited higher activity than the monometallic counterparts in catalytic transfer hydrogenolysis of native birch lignin, affording 37.2 wt % monophenols at 245 °C after 4 h. 4-Propylsyringol had the highest yield of 18.9 wt % with a selectivity of 51%. Among the three biomass feedstocks, native lignin in birch gave the highest monophenol yield, which is 2.2 times that of native pine lignin (16.9 wt %) and 4.6 times that of native corn stalk lignin (8.1 wt %). FTIR and Py–GC MS analyses of the starting biomasses and the depolymerization solid products revealed that native birch lignin has the highest depolymerization efficiency with the least active lignin remaining.
研究领域:
化学工程
·
可再生资源与环境科学
✓ 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）