67 research outputs found

    Selective Conversion of Lignin Catalyzed by Palladium Supported on N‑Doped Carbon

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    Highly selective conversion of lignin is essential to enable high-value utilization of lignin. Herein, we have prepared a palladium supported on N-doped carbon catalyst modified by 1,3,5-trimethylbenzene (TMB). The Pd nanoparticles are better dispersed on the TMB-modified catalyst than on the original catalyst. Therefore, the catalyst modified by TMB is more effective than the original catalyst in selectively converting lignin. When the organosolv lignin is catalyzed by 3 wt % Pd/CBFS-26-TMB (1:2) at 280 Β°C for 5 h, the yield of phenolic acid is 25.71 wt % and the biochar yield is only 4.5 wt %. Significantly, 52.59% of the phenolic acid monomers are 4-hydroxy-3,5-dimethoxyphenylacetic acid with a yield of 13.52 wt %. Thus, the catalyst 3 wt % Pd/CBFS-26-TMB (1:2) can effectively break the C–C and C–O bonds in the β–O–4 structure to convert lignin into 4-hydroxy-3,5-dimethoxyphenylacetic acid. We have also discussed the possible mechanism of lignin conversion into main products. This provides an essential approach for the high-value utilization of lignin

    Schematic illustration of sparse-strong and dense-weak styles of weighted community networks.

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    <p>The large circles denote the communities of the network, and the small circles denote the nodes. The lines denote the edges of the network, and its width represents the weight of the edges (i.e., the transmission rate between two nodes). The network parameters are: <i>N</i>β€Š=β€Š3 (number of communities), <i>M</i>β€Š=β€Š10 (number of nodes in each community), <i>d<sub>I</sub></i>β€Š=β€Š3 (average internal degree), <i>d<sub>E</sub></i>β€Š=β€Š0.2 or 1 (average external degree), <i>v</i>β€Š=β€Š0.5 (weight of internal edges) and <i>w</i>β€Š=β€Š0.10 or 0.47 (weight of external edges). The modularity <i>Q</i>β€Š=β€Š0.61 for both styles.</p

    Pd-catalyzed regioselective C-H chlorination of disubstituted 1,2,3-triazoles

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    This paper mainly studied Pd-catalyzed regioselective chlorination of disubstituted 1,2,3-triazoles directed by the 1,2,3-triazole ring. A series of regioselective chlorinated products were synthesized in 47–86% yields using Pd(OAc)2 as a catalyst and CuCl2 as a chlorinated reagent. This method provides a new mean for the synthesis of 1,2,3-triazole halides which combines the formation of C-X bond with C-H activation.</p

    Stability of Chlorogenic Acid from Artemisiae Scopariae Herba Enhanced by Natural Deep Eutectic Solvents as Green and Biodegradable Extraction Media

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    A green and inexpensive natural deep eutectic solvent (NADES) was screened and integrated with an ultrasonic technique for extracting chlorogenic acid (CGA) from artemisiae scopariae herba. Response surface methodology was employed to investigate significant factors and optimize their influence. Proline–malic acid exhibited an excellent extraction capacity with a yield of 28.23 mg/g under the optimal conditions of water content of 15% (wt), solid–liquid ratio of 1.0/10 (g/mL), ultrasonic power of 300 W, and extraction time of 25 min. Simultaneously, the stability and antioxidant activity analysis exhibited a better performance of CGA in NADES than that in water and ethanol. The hydrogen-bonding interaction between CGA and natural deep eutectic molecules enhanced the stability and meanwhile protected the antioxidant activity of CGA

    Study on Selective Preparation of Phenolic Products from Lignin over Ru–Ni Bimetallic Catalysts Supported on Modified HY Zeolite

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    The catalytic depolymerization of organic solvent lignin with the prepared catalyst 2.5Ru–10Ni/Al-HY was investigated in a high-pressure reactor. Effects of different catalysts, temperature, time, recyclability for catalyst, and solvents on the catalytic performance were explored. The optimal reaction conditions were reaction time 5 h and temperature 280 Β°C in ethanol solvent. As a result, the highest yield of phenolic monomers was 20.2 wt %, the yield of solid residue was only 4.8 wt %, and the gas products were CH4, C2H6, and CO mainly. With the increase of cycle times, the catalyst had no obvious deactivation, indicating a unique cycle stability. Through NMR characterization of lignin and depolymerization products, it was found that the signals of the original structures (A, B, and C) in lignin disappeared after reaction. According to the analysis of the reaction path, the depolymerization of lignin mainly included the depolymerization of lignin into reaction intermediates and the formation of phenolic compounds by breaking chemical bonds. This research showed a method for preparing phenolic products by the molecular sieve catalyzed depolymerization of lignin

    A comparison of the theoretical and the simulated epidemic size and threshold.

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    <p>The curves depict the average epidemic size as a function of the external transmission rates in the simulations, and the points denote the theoretical values of the epidemic size in three situations (calculated using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0057100#pone.0057100.e016" target="_blank">Eq. 16</a>). The Network parameters are <i>N</i>β€Š=β€Š500, <i>M</i>β€Š=β€Š500, <i>v</i>β€Š=β€Š0.2. We use mean value and range to define a degree distribution. The mean value of internal Poisson () and Power-law distribution () is 1.2, and the mean value of external Poisson and Power-law distribution is 1. The maximal internal degree does not exceed 10 in simulations. There are three combinations of internal and external degree distributions: internal Poisson with external Poisson (red circles), internal Power-law with external Poisson (green rectangles), and internal Poisson with external Power-law (cyan triangles). The recovery rate <i>Ξ³</i>β€Š=β€Š1 in the SIR simulations.</p

    Detail effects of mixing style.

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    <p>(A) and (B) average epidemic size and maximal epidemic entropy as a function of the number of communities. Network parameters are <i>N</i>β€Š=β€Š2 to 20, <i>M</i>β€Š=β€Š50, <i>d<sub>I</sub></i>β€Š=β€Š4, <i>d<sub>E</sub></i>β€Š=β€Š0.04 or 1, <i>v</i>β€Š=β€Š0.5 and <i>w</i>β€Š=β€Š0.49 or 0.02. The modularity <i>Q</i>β€Š=β€Š0.49 to 0.94, and is the same for both styles for each <i>N</i>; (C) and (D) average epidemic size and maximal epidemic entropy as a function of the connection density. Network parameters are <i>N</i>β€Š=β€Š20, <i>M</i>β€Š=β€Š50, <i>d<sub>I</sub></i>β€Š=β€Š4, <i>d<sub>E</sub></i>β€Š=β€Š0.04 to 0.5, <i>v</i>β€Š=β€Š0.5 and <i>w</i>β€Š=β€Š0.49 or 0.02. The modularity <i>Q</i>β€Š=β€Š0.94 for all networks with different connection densities; (E) average epidemic size (the ratio of infected nodes to total number of nodes in original networks) as a function of immunization ratio, which is the ratio of nodes with immune state (i.e. cannot be infected). The targeted immunization of nodes is according to the descending order of their external degree. The Network parameters are <i>N</i>β€Š=β€Š20, <i>M</i>β€Š=β€Š50, <i>d<sub>I</sub></i>β€Š=β€Š4, <i>d<sub>E</sub></i>β€Š=β€Š0.04 or 1, <i>v</i>β€Š=β€Š0.5 and <i>w</i>β€Š=β€Š0.49 or 0.02. The modularity <i>Q</i>β€Š=β€Š0.94 for both mixing styles. Solid curves represent sparse-strong style networks and dashed curves represent dense-weak style networks. The recovery rate <i>Ξ³</i>β€Š=β€Š0.35 in all SIR simulations.</p
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