POLYMER
·
2024
·
IF 4.1
Zaoxia Wen,Liang Xu,Xingyu Liu,Linxuan Fang,Lianbin Wu
A novel method was developed for constructing cross-linked silsesquioxane, utilizing Q-type H-POSS as a precursor. The Piers-Rubinsztajn (P–R) like reaction of Q-type H-POSS was catalyzed by B(C 6 F 5 ) 3 , resulting in the production of a prepolymer containing partial Si–H. Upon heating at high temperature in air, the prepolymer transformed into an insoluble and infusible cross-linked polymer, named Cured poly(H-POSS). This polymer exhibited high thermostability, with a 5 % weight loss temperature ( T 5d ) of 709 °C and a residue of 92 % at 800 °C. Additionally, Cured poly(H-POSS) exhibited high transparency, with a transmittance of 90 % in the 400–800 nm wavelength range, and favorable dielectric properties, with a dielectric constant ( D k ) of 2.88 at 14 GHz.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Catalysts
·
2024
·Vol. 14
·期 4
·248
·
IF 3.8
Xinyi Xing,Wanni Liu,Siquan Xu,Jianxiu Hao
H-Beta zeolite is a solid acid catalyst commonly utilized in the catalytic conversion of biomass resources. In this study, H-Beta zeolite was calcined at different temperatures (350, 550, 750, and 1000 °C) to explore the effects of high temperature-induced dealumination on its physicochemical properties and its catalytic ability to convert glucose into 5-hydroxymethylfurfural (HMF). It was shown that as the calcination temperature increased, the Si-O-Al bond of H-Beta zeolite was broken and its dealumination effect was enhanced. Dealumination led to the collapse of the framework of H-Beta zeolite and a reduction in the number of acid sites, which in turn reduced its catalytic performance and the efficiency of HMF formation from glucose. Furthermore, H-Beta zeolite exhibited an extraordinary catalytic ability for the production of HMF from carbohydrates. Using glucose and cellulose as substrates, superior HMF yields of 91% and 46%, respectively, were achieved under optimal reaction conditions. Further, calcination removes carbon deposits in the recovered H-Beta zeolite, but it affects the cycling stability of the catalyst. Meanwhile, the by-products formed during the synthesis of HMF from glucose catalyzed by H-Beta zeolite catalyst were also clearly detected.
研究领域:
催化化学
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生物质转化
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产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 20
·6268-6284
·
IF 6.177
Tingyu Liang,Jialing Chen,Sen Wang,Pengfei Wang,Zhangfeng Qin,Fang Jin,Mei Dong,Jianguo Wang,Weibin Fan
A series of H-MCM-22 zeolites with different Si/Al ratios (H-M22-x, x = 15–90) were hydrothermally synthesized by boron incorporation to investigate the influences of acid density on the methanol-to-hydrocarbon (MTH) performances and deactivation behaviors. The acid density of H-M22-x zeolites is nearly proportional to their aluminum contents; the residual boron barely affects the overall acidity of H-M22-x zeolites. 27Al and 29Si MAS NMR experiments support the existence of competitive occupancy of various framework T sites among boron, aluminum and silicon during zeolite synthesis, which leads to different distribution of Brønsted acid sites/framework aluminum among three types of pores in H-MCM-22 zeolites. Increasing the Si/Al ratio of H-M22-x zeolites leads to a gradual increase in the proportion of Brønsted acid sites in supercages while those in sinusoidal channels decrease. However, the acid density has a significantly larger impact than acid distribution on the MTH performances of H-M22-x zeolites. Increasing the acid density can accelerate the hydrogen transfer reactions in the MTH conversion and promote the formation of aromatics, ethene, and alkanes. The deactivation of H-M22-x zeolites with low acid density (x = 50–90) is mainly ascribed to coke covering the acid sites inside the micropores and partly blocking the pore mouths. Nevertheless, the deactivation of H-M22-x zeolites with high acid density (x = 15–30) is mainly caused by massive coke deposition on the external surface which blocks the pore mouths of inner micropores. The coke on the external surface exhibits a lower decomposition temperature than that inside the micropores. The deactivation behaviors of H-M22-x zeolites for the MTH reaction can be divided into three stages. Firstly, rapid deactivation of supercages occurred for all the H-M22-x zeolites in spite of their different acid densities, suggesting a much stronger influence of pore structure than acidity on the initial deactivation behaviors of H-M22-x zeolites. Secondly, the acid sites in sinusoidal channels of H-M22-x zeolites are highly resistant to coke formation, which dominates the MTH reaction in the second stage. Finally, with the continuous formation of coke in the surface pockets, which gradually covers the acid sites and pore mouths of sinusoidal channels, complete deactivation of H-M22-x zeolites can be observed. GC-MS and UV-vis analysis of partly or completely deactivated H-M22-x zeolites reveals that the retained species in H-M22-x zeolites gradually condense into bulky hydrocarbon species through successive hydrogen transfer reactions and form methylbenzenes, naphthalene, polymethylnaphthalenes, phenalenone, pyrenes and eventually graphite-like carbonaceous species.
研究领域:
催化化学
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材料科学
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能源化学
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产品关联
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2019
·
IF 4.191
Xiaoyun Li,Jiaxin Yang,Rui Xu,Lefu Lu,Fangong Kong,Min Liang,Lijie Jiang,Shuangxi Nie,Chuanling Si
The production of platform chemicals from lignocellulosic biomass is scientifically valuable but technologically challenging. With the aim to establish a green reaction system for the production of furfural from lignocellulosic biomass, in the current work, H-SAPO-34 was investigated for catalysis of the conversion of Eucalyptus sawdust to furfural in γ-valerolactone (GVL). H-SAPO-34 was prepared and characterized by XRD, SEM, FTIR, BET, TGA and ammonia adsorbed FTIR. H-SAPO-34 possesses Brønsted and Lewis acid sites and a large specific surface area. The average pore diameter of H-SAPO-34 was 0.86 nm, which is beneficial for the spread of xylose and furfural and the inhibition of humin production. In this work, a peak furfural yield of 99.28% from Eucalyptus was achieved at 210 °C in 120 min with 30 g/L H-SAPO-34. The Brønsted/Lewis acid bifunctionality and the solvent effect of γ-valerolactone possibly contributed to the high furfural yield from real biomass. The kinetics of the conversion of Eucalyptus sawdust to furfural was also studied, and the activation energy for furfural production was calculated. Additionally, the catalytic activity and stability of the regenerated catalyst were estimated.
研究领域:
化学工程
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可再生资源与环境科学
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产品关联
DOI
高影响因子
ANALYTICAL BIOCHEMISTRY
·
2016
·
IF 2.243
Wei Zhang,Min Zhu,Feng Wang,Danhui Cao,Jennifer Jin Ruan,Weike Su,Benfang Helen Ruan
Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of L-glutamate and is important for several biological processes . For GDH inhibitor screening, we developed a novel mono-sulfonated tetrazolium salt (EZMTT), which can be synthesized using H 2 O 2 oxidation and purified easily on silica gel in large quantities. The EZMTT detection method showed linear dose responses to NAD(P)H, dehydrogenase concentration and cell numbers. In E. coli GDH assay, the EZMTT method showed excellent assay reproducibility with a Z factor of 0.9 and caused no false positives in the presence of antioxidants (such as BME). Using the EZMTT-formazan-NAD(P)H system, we showed that EGCG is a potent E. coli GDH inhibitor (IC 50 45 nM) and identified that Ebselen , a multifunctional thioredoxin reductase inhibitor, inactivated E. coli GDH (IC 50 213 nM). In cell-based assays at 0.5 mM tetrazolium concentration, EZMTT showed essentially no toxicity after a 3-day incubation, whereas 40% of inhibition was observed for WST-8. In conclusion, EZMTT is a novel tetrazolium salt which provides improved features that are suitable for dehydrogenases and real-time cell-based high-throughput screening (HTS).
研究领域:
生物化学
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药物筛选
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细胞生物学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2016
·Vol. 99
·期 8
·2615-2624
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IF 2.787
Zhaoju Yu,Pei Zhang,Yao Feng,Shuang Li,Yaxing Pei
We present a template-free synthesis of Fe 3 O 4 /SiOC(H) nanocomposites with in situ formed Fe 3 O 4 nanoparticles with a size of about 50 nm embedded in a nanoporous SiOC(H) matrix obtained via a polymer-derived ceramic route. Firstly, a single-source precursor (SSP) was synthesized by the reaction of allylhydridopolycarbosilane (AHPCS) with Fe-acetylacetonate [Fe(acac) 3 ] at 140°C. The SSP was heat-treated at 170°C to generate Fe 3 O 4 nanocrystals in the cross-linked polymeric matrix. Subsequently, the SSP was pyrolyzed at 600°C–700°C in argon atmosphere to yield porous Fe 3 O 4 /SiOC(H) nanocomposites with the high BET surface area up to 390 m 2 /g, a high micropore surface area of 301 m 2 /g, and a high micropore volume of 0.142 cm 3 /g. The Fe-free SiOC(H) ceramic matrix derived from original AHPCS is nonporous. The in situ formation of Fe 3 O 4 nanoparticles embedded homogeneously within a nanoporous SiOC(H) matrix shows significantly enhanced catalytic degradation of xylene orange in aqueous solution with H 2 O 2 as oxidant as compared with pure commercial Fe 3 O 4 nanoparticles.
研究领域:
材料科学
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化学工程
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环境科学
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产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
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2025
·
IF 4.7
Qiang-Qiang Ma,Peng Zhou,Yizhen Liu,Zuowei Xie
Transition metal catalyzed selective cage B–H functionalization of carboranes has made significant progress in recent years, giving rise to the efficient synthesis of a large variety of cage B-functionalized carboranes including alkenylation, arylation, alkynylation, borylation, hydroxylation, acyloxylation, amination, and halogenation. However, the mechanisms of these catalytic B–X coupling reactions are not well understood. Herein, we describe the isolation and characterization of the catalytically relevant o-carborane based palladium(II) metallacycle, disclosing the details of Pd-catalyzed B–H functionalization of o-carboranes. As a result, highly selective catalytic B(3,6)-dihalogenation, -dimethylation, and -diarylation of o-carboranes have been achieved.
研究领域:
有机化学
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过渡金属催化
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材料化学
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产品关联
DOI
PubMed
高影响因子
CEMENT & CONCRETE COMPOSITES
·
2023
·
IF 10.5
Zhongtao Luo,Tianyi Zhi,Xiaohai Liu,Kunpeng Yin,Han Pan,Hu Feng,Yatao Song,Yanfeng Su
The early hydration of UHPC can be retarded by the low water/binder ratio, the high polycarboxylate superplasticizers dosage, and the large supplementary cementitious materials (SCM) content. In this study, the effects of the prepared nanoscale C–S–H seeds and nano-silica (NS) on the early performance of UHPC were compared. The mechanism of nanomaterials influencing the early hydration of UHPC was further characterized by calorimetry , thermal analysis, nuclear magnetic resonance (NMR), and mercury intrusion porosimetry . The results showed that the 1-day compressive strength of UHPC samples with 0.3 wt% C–S–H seeds and NS increased by 457% and 25% respectively compared to the control sample. Compared to NS, C–S–H seeds were more effective in accelerating the early (before 3 d) hydration to produce hydrates and refine the pore structure of UHPC. The NMR results further implied that compared with the NS, the C–S–H seeds was 12% and 343% more efficient in accelerating the early hydration of cement and SCMs, respectively. However, the performance enhancement of nanomaterials was effective at 1 d and had little effect thereafter.
研究领域:
土木工程
·
材料科学
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DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2023
·
IF 3.6
Huanhuan Song,Jingwen Li,Yinbin Zhang,Ke Chen,Le Liu,Junjie Zhang,Xin-Hua Duan,Mingyou Hu
Difluoromethylated heterocyclic compounds have found broad applications in numerous bioactive molecules. Herein, we report photoredox catalysis-induced direct C–H difluoromethylation of heterocycles by using bis(difluoromethyl) pentacoordinate phosphorane (PPh3(CF2H)2, 1) as the reagent. A variety of heterocycles, such as quinoxalin-2(1H)-one, thiophene, indole, and coumarin, are readily tailored with a difluoromethyl group. The method is featured as transition-metal-free by using an organic compound Erythrosin B as the catalyst and O2 as the oxidant.
研究领域:
有机化学
·
药物化学
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DOI
PubMed
高影响因子
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2020
·Vol. 126
·期 7
·1-9
·
IF 1.81
He Bing,He Wenhui,Wang Yawen
Semiconductor photocatalyst as a new type of green and sustainable energy material has extensively used in wastewater and gas treatment. In this work, we prepared Pt/h-BN/BiOBr composite by an alcohol-soluble hydrolysis-assisted photoreduction method. The photocatalytic activity was evaluated by the degradation of bisphenol A under simulated sunlight, and the degradation efficiency of BiOBr, h-BN/BiOBr, Pt/BiOBr, and Pt/h-BN/BiOBr were 55.13%, 74.91%, 89.00%, and 98.54%, respectively. The results showed single composited with h-BN or Pt could improve the photocatalytic performance of BiOBr, while double composited with h-BN and Pt could play a synergistic effect on further improving the activity. The interaction between h-BN and BiOBr was electrostatic interactions, and that Pt as a plasma metal was coupling with BiOBr due to its localized surface plasmon resonance (LSPR) effect. The composition, morphology, optical property, and separation efficiency of photo-induced carriers and dominant active radicals were investigated. Based on the results, a possible mechanism was proposed. The excellent photocatalytic activity of Pt/h-BN/BiOBr composite photocatalyst could be attributed to the broadened light-response range after Pt loading, and enhanced electron–hole separation efficiency due to the electron capturer role of Pt and the hole transfer function of h-BN.
研究领域:
环境科学
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材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2022
·Vol. 57
·期 42
·19799-19816
·
IF 4.682
Zhu Jishi,Li Xinshuo,Yang Rui,Wen Jin,Li Xiaoke
The widespread application of solar-thermal absorbers is currently hindered by their low absorption efficiency and high capital cost. Therefore, many initiatives, including direct absorption solar collectors (DASCs), are currently under way to improve the efficiency of the absorbers. In this regard, the application of TiN-modified h-BN nanosheets in DASCs is studied in this paper. Their superior solar absorptivity and thermal conductivity are based on the plasma plasmon effect of nanoparticles and the high thermal conductivity of h-BN nanosheets, respectively. In the experiment, five different concentrations (20, 40, 60, 80, 100 ppm) of TiN@h-BN composite nanofluids were prepared by a two-step method. The stability and optical properties of the nanofluids were analyzed. In addition, thermal loss and exergic efficiency of photothermal conversion system were analyzed and discussed. Combined with localized surface plasmon resonance (LSPR) of TiN nanoparticles and h-BN light reflection properties, the photothermal conversion of TiN@h-BN composite nanofluids was improved in DASCs. The 80 ppm nanofluid showed the best exergic efficiency, with an average exergic efficiency of 83%. Meanwhile, the photothermal conversion efficiency of 80 ppm TiN@h-BN composite nanofluid reaches the maximum 78%. This work provides new strategies for harnessing the full spectrum of solar energy and controlling the photothermal properties of nanofluids. Graphical Abstract Schematic diagram of photothermal conversion system of TiN@h-BN nanofluids.
研究领域:
材料科学
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能源工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2024
·
IF 3.4
Chenan Yang,Yi Liu,Ying Hu,Peng Wang,Yuling Yang,Shangxing Chen,Zongde Wang,Xiang Li
Catalytic valorization of biomass into high energy density fuels plays a vital role in order to achieve future carbon neutrality. Herein, a class of H-MZ-5 catalysts with different mesoporous pore structures and acid site properties were synthesized. Among them, HMZ-5 prepared with tetrapropylammonium bromide (TPABr) and hexadecyltrimethylammonium bromide (CTAB) as templating agents showed the most excellent catalytic activity and selectivity of α-pinene dimerization. Under optimal catalytic conditions, 100% α-pinene was converted with 89.6% selectivity to dimers. The efficient catalytic activity and affordability of the catalysts in this system make it promising for industrial applications.
研究领域:
化学工程
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能源科学
·
催化材料
✓ 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）