FUEL
·
2023
·
IF 7.4
Ziyu Jia,Jun Hu,Ping Lu,Yahui Sun,Yunjun Wang
Herein, using Ru/C and H 2 WO 4 as the catalysts, native lignin in biomass was efficiently depolymerized into monophenols following the lignin-first strategy at mild conditions. Upon the co-presence of Ru/C and H 2 WO 4 , birch lignin afforded monophenols in 40.4 wt% yield at 200 °C, which was 2.5 times that upon Ru/C and 7.5 times that upon H 2 WO 4 . 4-Propylsyringol and 4-propylguaiacol were two major products with a combined selectivity of 73%. 2D HSQC NMR of liquid product reveals that β-O-4 bonds in the soluble lignin fragments had been thoroughly disrupted. H 2 WO 4 dissolving at high temperatures promoted the solvolysis of lignin from the biomass matrix, and Ru/C enhanced the following reductive depolymerization. The solid catalysts can be readily recovered for reuse at room temperature after the hydrolysis of carbohydrates, and the catalysts exhibited high activity after four recycles.
研究领域:
生物化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 40
·23061-23070
·
IF 3.049
Libo Peng,Qinglong Xie,Yong Nie,Xuejun Liu,Meizhen Lu,Jianbing Ji
The oxidative cleavage of vegetable oils and their derivatives to produce bio-based aldehydes is a potentially useful process, although the aldehyde products are readily oxidized to carboxylic acids and thus seldom obtained in high yields. The present study developed a room-temperature method for the synthesis of bio-aldehydes via the oxidative cleavage of vegetable oil-derived epoxides, using H2WO4 as the catalyst, H2O2 as the oxidant, and t-BuOH as the solvent. Reactions were carried out at temperatures ranging from 25 to 35 °C for 3.5–10.5 h, and provided >99% conversion and >90% aldehyde yield. In particular, an approximately 97% yield was obtained at 25 °C after 10.5 h. As the reaction proceeded, the H2WO4 dissolved to form a W-containing anion. Several mesoporous Al-MCM-41 materials having different Si/Al ratios were hydrothermally synthesized and used as adsorbents to recover the catalyst by adsorbing these anions. The adsorption capacity of the Al-MCM-41 was found to increase with decreases in the Si/Al ratio. The Al-MCM-41 had little effect on the oxidative cleavage reaction at 25 °C, and thus could be directly added to the reaction system. The excellent anion adsorption performance of the Al-MCM-41 greatly improved the reusability of the H2WO4 catalyst. When using the Al-MCM-41 with the best adsorption performance, there was no significant decrease in the activity of the catalyst following five reuses.
研究领域:
化学工程
·
生物化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 5
·2764-2771
·
IF 3.049
Fuhang Mai,Kai Cui,Zhe Wen,Kai Wu,Fei Yan,Mengmeng Chen,Hong Chen,Yongdan Li
The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Brønsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
研究领域:
化学工程
·
催化
·
有机化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Guang Yang,Daming Hu,Fang Xia,Chuanfan Yang,Yongwei Liu,Xiaoyan He,Yaroslav Shpotyuk,Hongfei Chen,Yanfeng Gao
Tungsten bronze is an effective near-infrared (NIR) shielding material for fabricating energy-saving smart windows. While high-performing NIR-shielding glasses can be fabricated by coating a tungsten bronze film on window glasses, these glasses suffer a short lifespan due to the adhesion and degeneration of film. In this work, we show that tungsten bronze-like material Na5W14O44 can be distributed in the bulk glass matrix during the facile melt-quenching glass fabrication process under an air atmosphere, overcoming the limitations of film-based glasses. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the presence of tungsten bronze-like Na5W14O44 functional units in the SiO2–B2O3–NaF glass matrix. The addition of a small amount of H2WO4 and Sb2O3 is critical for the formation of Na5W14O44 functional units because H2WO4 provides W for Na5W14O44, and Sb2O3 acts as a reducing agent that helps the formation of W5+ in Na5W14O44 under an air atmosphere. Furthermore, the NIR-shielding ability can be tuned by adjusting the concentration of Sb2O3 in the range of 0–1.5 mol % and of H2WO4 in the range of 4–6 mol %. The optimized composition containing 1.25 mol % of Sb2O3 and 5 mol % of H2WO4 exhibits excellent NIR-shielding ability (ΔT = 62.8%), high visible light transmittance (Tmax = 67.7%), and excellent thermal insulation. This performance is comparable to cesium tungsten bronze film-based glasses and much better than soda lime glass and ITO glass under sun irradiation. This study sheds light on fabricating energy-saving windows in a simple and cost-effective way with flexibility for fine tuning of NIR-shielding performance.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL PAPERS
·
2017
·Vol. 72
·期 3
·643-649
·
IF 1.258
Wang Bingtong,Zhang Zongbin,Zhang Xinyu,Sun Shixin,Wu Lin,Xing Rong
A simple, efficient, and eco-friendly catalytic system for the oxidation of cyclohexene to adipic acid with H 2 O 2 catalyzed by H 2 WO 4 in Brønsted acidic ionic liquids under solvent-free conditions has been developed. Reaction conditions such as the catalysts, the types of anions and cations for Brønsted acidic ionic liquids, reaction temperature, and the amount of hydrogen peroxide, were investigated. Moreover, the Hammett acidity functions ( H
0 ) of Brønsted acidic ionic liquids were determined using UV–visible spectrophotometry. The optimum reaction condition identified was n(H 2 WO 4 ):n(Brønsted acidic ionic liquids): n (cyclohexene): n (H 2 O 2 ) = 0.02:0.02:1:4.4, and the yield of adipic acid was 96% under the reaction scale of 10 mmol. The catalytic system can be easily recovered and reused for four reaction runs without significant loss of catalytic activity. Simple operation of the catalyst system and avoidance of the emission of nitrous oxide are the benefits of this work.
研究领域:
化学
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 22
·13914-13937
·
IF 3.442
Pudukudy Manoj,Jia Qingming
A controlled acidic precipitation is reported for the direct synthesis of nanosheets self-assembled hierarchical tungstic acid microspheres, and their annealing-dependent thermal conversion into WO 3 microstructures is studied for the first time. The synthesis was carried out without the use of any structure directing agents and hydrothermal conditions. The microspheres were found to be consisting of many single-crystalline and highly oriented nanosheets that were hierarchically self-aggregated in spherical form for the minimization of surface energy. An experimentally validated time-dependent formation and growth mechanism was proposed for the development of microspheres. The characterization results indicated that the morphology-preserved thermal decomposition of H 2 WO 4 into WO 3 microspheres occurred at 400 °C, whereas a morphology distortion was noticed for the sample synthesized at 600 °C. The increase in annealing temperature further increased the crystallinity of WO 3 without changing its monoclinic crystal structure. However, it has a diminishing effect in the specific surface area, pore size and pore volume of the annealed samples. Moreover, the adsorption of methylene blue in aqueous medium was carried out to evaluate its potential environmental application. The WO 3 microspheres synthesized at 400 °C showed high adsorption capacity (63 mg/g) compared to the same at 600 °C (56 mg/g). The high activity could be ascribed to the synergistic effects of high surface area, low particle size, porosity, specific morphology and more negative zeta potential. The adsorption further followed pseudo-second-order kinetics with a best fit of the experimental and theoretical values.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）