ORGANIC & BIOMOLECULAR CHEMISTRY
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2014
·Vol. 12
·期 18
·2969-2978
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IF 3.487
Jiajun Zhang,Pinhua Li,Lei Wang
A novel KOAc-promoted α-position C–H activation and alkynylation of ethers with alkynyl bromides to 2-alkynyl ethers has been developed under transition-metal-free and simple reaction conditions. In addition, this methodology can also be extended to the vinylation of ethers with vinyl bromides in excellent regio- and stereo-selectivity. A wide range of direct C(sp)–C(sp3) and C(sp2)–C(sp3) bonds has been formed through this protocol, which offers a new and alternative route.
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ORGANIC & BIOMOLECULAR CHEMISTRY
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2014
·Vol. 12
·期 21
·3493-3498
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IF 3.487
Yaping Zhao,Lu Sun,Tieqiang Zeng,Jiayi Wang,Yanqing Peng,Gonghua Song
Copper-catalyzed direct olefination of benzaldehydes into 1,3-diarylpropenes by a novel domino Knoevenagel-decarboxylation-Csp3-H activation sequence is reported. This method provides a concise and effective route toward the synthesis of unsymmetrical 1,3-diarylpropene derivatives.
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CHEMICAL ENGINEERING JOURNAL
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2015
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IF 4.321
Lei Yue,Guangqian Li,Guijin He,Yongsheng Guo,Li Xu,Wenjun Fang
The precise investigations on modeling properties and performance of practical fuels are usually complicated because of the multi-component nature. On the basis of hydrogen to carbon ratio (H/C), as a simple and overall characterization parameter for hydrocarbon fuels, this work provides a comprehensive insight into the study of kerosene-based hydrocarbon fuels (H/C = 1.6–2.3). The fundamental properties and supercritical cracking performance of hydrocarbon fuels are influenced intrinsically by their H/C values and molecular weights ( M ) due to the compositional and structural effects. Thus, a new combined parameter, (H/C)/ M a , is proposed to model the performance of hydrocarbon fuels. It is found that the hydrocarbon fuel with a higher H/C has a higher net heating value, and that with a higher (H/C)/ M 0.1 has a lower density. The viscosity decreases with the increase of (H/C)/ M 0.5 . The flash point shows a decreasing trend against the increase of (H/C)/ M 2 . The densities, viscosities and net heating values of 23 hydrocarbon fuels are calculated by means of the regression equations with the H/C and M data, and they are in agreement with the corresponding experimental values with the relative errors less than 2.5%, 10% and 1.5%, respectively. As investigated in an electrically heated tube reactor, the hydrocarbon fuel with a higher H/C performs thermal cracking more easily, absorb more heat and form fewer cokes. As a result, the cracking performance of hydrocarbon fuels can be predicted reasonably to a certain extent on the basis of H/C values.
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MOLECULES
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2017
·Vol. 22
·期 7
·1068
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IF 2.861
Yalu Dong,Panpan Peng,Baoping Hu,Hui Su,Shenghua Li,Siping Pang
High-energy metal–organic frameworks (MOFs) based on nitrogen-rich ligands are an emerging class of explosives, and density is one of the positive factors that can influence the performance of energetic materials. Thus, it is important to design and synthesize high-density energetic MOFs. In the present work, hydrothermal reactions of Cu(II) with the rigid polynitro heterocyclic ligands 5,5′-dinitro-2H,2′H-3,3′-bi-1,2,4-triazole (DNBT) and 5,5′-dinitro-3,3′-bis-1,2,4-triazole-1-diol (DNBTO) gave two high-density MOFs: [Cu(DNBT)(ATRZ)3]n(1) and [Cu(DNBTO)(ATRZ)2(H2O)2]n(2), where ATRZ represents 4,4′-azo-1,2,4-triazole. The structures were characterized by infrared spectroscopy, elemental analysis, ultraviolet-visible (UV) absorption spectroscopy and single-crystal X-ray diffraction. Their thermal stabilities were also determined by thermogravimetric/differential scanning calorimetry analysis (TG/DSC). The results revealed that complex1has a two-dimensional porous framework that possesses the most stable chair conformations (like cyclohexane), whereas complex2has a one-dimensional polymeric structure. Compared with previously reported MOFs based on copper ions, the complexes have higher density (ρ = 1.93 g cm−3for complex1and ρ = 1.96 g cm−3for complex2) and high thermal stability (decomposition temperatures of 323 °C for complex1and 333.3 °C for complex2), especially because of the introduction of an N–O bond in complex2. We anticipate that these two complexes would be potential high-energy density materials.Keywords:energetic materials;metal organic frameworks;densities;polynitro heterocyclic ligands
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CERAMICS INTERNATIONAL
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2016
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IF 2.758
Fengrui Zhai,Shuang Li,Jialin Sun,Zhongzhou Yi
h -BN-SiC ceramic composites with different SiC contents were fabricated by spark plasma sintering . The results indicate that the addition of hard SiC particles has a remarkable effect on the densification, microstructure, mechanical properties and thermal shock resistance of the composites. Compared with pure h -BN ceramic, the relative density and mechanical properties of h -BN-SiC ceramic composites were improved obviously. The optimal properties of h -BN-SiC ceramic composites were obtained at SiC content of 25%, and the relative density, flexural strength and fracture toughness reached 97.8%, 289.2 MPa and 3.45 MPa m 1/2 , respectively. Moreover, the relationship of fracture toughness and fracture mode was discussed. The thermal shock test results showed that the h -BN-SiC ceramic composite with the SiC content of 25% exhibited excellent thermal shock resistance, presenting critical temperature difference up to 900 °C. The high temperature oxidation of h -BN and SiC on material surface led to the formation of borosilicate glass phase, which could heal the surface microcracks and then improve the thermal shock resistance.
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CEMENT AND CONCRETE RESEARCH
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2024
·
IF 10.9
Binmeng Chen,Xu Fang,Yuyang Zhao,Zongjin Li
In recycling and reusing construction waste, carbonation of recycled concrete fine (RCF) has been successfully applied to produce value-added products, such as silica nanoparticles, via the breaking of calcium silicate hydrate (C-S-H) structure and condensation of silicate chains. However, the intricacies of carbonation of RCF with varying calcium to silicon (C/S) ratios and their implications on the size of generated silica nanoparticles remain unknown. In this work, we developed an optimized carbonation method at high water to solid ratio to fabricate silica nanoparticles from C-S-H with different C/S ratios. The particle size of silica nanoparticles was found to gradually decrease with the increased C/S ratio of C-S-H. Since as C/S ratio increased, silicate in Q 3 state shifted to Q 1 state and the silicate chain became shorter, shifting from long-range, disordered to short-range, ordered. As the disordered self-seeding growth of long silicate chains derived from C-S-H continued, the Si-O-Si network of silica nanoparticles became chaotic, leaving more unreacted Si-OH on its surface. On the contrary, the short silicate chains displayed higher possibility of condensation, making nanoparticles with a smaller diameter.
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CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Zhefei Zhao,Xuyao Yao,Ruopeng Yu,Xingyu Luo,Minhao Chen,Xiangxiang Zhang,Yinghua Xu,Youqun Chu,Xinbiao Mao,Huajun Zheng
Electrocatalytic hydrodechlorination (EHDC) stands out as an economical and prospective technology for eliminating chlorinated organic pollutants. Single-atom catalyst engineering and metal-support interaction (MSI) offer the promising strategies for developing electrocatalysts with high atom utilization and reactivity. Herein, atomically dispersed palladium (Pd) anchored on the iron (Fe)-introduced nickel phosphide (NiFeP) support is reported. The prepared NiFeP-Pd electrode exhibits outstanding electrocatalytic activity in 4-CP removal efficiency (98.8 %) with an ultra-low dosage of Pd (0.0497 mg cm −2 ) and the highest reported MA value (446.01 min −1 g −1 ), surpassing Ni 2 P-Pd by 6.34 times. Experimental results combined with theoretical calculations suggest that the superior performance of NiFeP-Pd stems from the modulated support by Fe introduction, which not only enhances the generation of adsorbed atomic hydrogen species (H*), but also reduces the energy barrier of C-H formation on Pd sites by regulating the MSI. In addition, single-Pd-atom construction on NiFeP with good conductivity and large specific surface area makes the contributions as well.
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PROGRESS IN ORGANIC COATINGS
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2024
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IF 6.5
Beibei Chen,Wenquan Dong,Wenchao Shi,Xuanlin Li,Bi Yang,Yang Tong,Lin Zhang,Jianzhang Wang
Developing high-performance of organic solid lubricating coating is of great significance for extending the life of the moving systems/parts. Herein, the non-covalently modified h-BN nanosheets by graphene oxide (BNNSs/GO) were elaborately constructed to enhance the mechanical, friction and wear properties of epoxy nanocomposite coating. The microstructure feature and chemical composition of BNNSs/GO were determined by various spectroscopic techniques. The tribological performance of nanocomposite coatings were tested using ball-on-disc friction tester, and 440C stainless-steel ball with diameter of 8 mm was used as the counterface material. The GO nanosheets acted an active platform for BNNSs, which improved the dispersion of BNNSs and interface interaction with epoxy. The anchoring BNNSs could break the strong π-π, and van der Walls forces among GO nanosheets. The thickness of epoxy nanocomposite coatings was about 60 μm. And the epoxy-1.0 wt%BNNSs/GO demonstrated much higher hardness and elastic modulus than epoxy, increased by 112.62 % and 53.37 %, respectively. The coefficient of friction (COF) and wear rate of epoxy-1.0 wt%BNNSs/GO were the lowest, with a reduction of 89.7 % and 97.5 %, respectively. The synergistic lubricating mechanism of epoxy-BNNSs/GO coating was proposed, which could provide a new light on the design of high antifriction and wear resistance of organic nanocomposite coating.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2017
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IF 2.536
Huihui Li,Cailing Yang,Xinyue Zhu,Haixia Zhang
A simple ratiometric fluorescent sensor for fructose was presented. It consisted of 10-hydroxybenzo[ h ]quinoline (HBQ) which showed emission at 572 nm and 3-pyridylboronic acid (PDBA) whose complex with HBQ gave emission at 500 nm. The reaction of fructose with PDBA inhibited the complexation of HBQ with PDBA, resulting in the change of dual-emission intensity ratio. The sensor well quantified fructose in the range of 0.015–2.5 mM with detection limit of 0.005 mM. Besides, this sensor exhibited excellent selectivity and was successfully applied to fructose detection in food. This work provides a simple ratiometric sensing platform for sensitive and selective detection of fructose.
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CATALYSIS COMMUNICATIONS
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2024
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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.
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Catalysts
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2024
·Vol. 14
·期 4
·248
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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.
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POLYMER
·
2024
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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.
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