JOURNAL OF APPLIED POLYMER SCIENCE
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2016
·Vol. 134
·期 1
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IF 1.866
Zhaowei Wang,Zhixia Wen,Xing Li,Junwei Yu,Xiaoxuan Liu
The preparation of the high cis −1,4-polyisoprene by Ziegler-Natta catalysis system was studied. The effect of Al-Ti catalysts modified by ethers with different structures which are different electron donor reagent on polymerization of isoprene has been mainly investigated. By the measurement method of the monomer conversion, FTIR, and 1 H NMR spectroscopy, the influence of, respectively, added diphenyl ether, anisole, dibutyl ether, or methyl tert -butyl methyl ether as a third active component on the heterogeneous TiCl 4 -Al( i -Bu) 3 -ether catalyst activity and microstructure of synthetic polyisoprene was analyzed. By the adding of diphenyl ether or dibutyl ether, the process of prefabricated heterogeneous catalyst is quickly and catalyst particle quantity is large. The polymerization conversion is high and the microstructure cis −1,4 content of the resulting polymer can reach 92%. But Al( i -Bu) 3 added anisole or methyl tert -butyl methyl ether hard to cooperate with TiCl 4 . © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44357.
研究领域:
高分子化学
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催化化学
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功能材料
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合成高分子
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配位聚合
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ECS Journal of Solid State Science and Technology
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2023
·Vol. 12
·期 2
·023010
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IF 2.2
Zhentao Wang,Haisheng Zheng,Lei Zhang,Zhan Cheng,Feiwen Zhao,Ruzhong Zuo,Tianyu Li,Dong Xu
In this paper, (M0.5Ta0.5)0.05Ti0.95O2 (M = Al, Ga, In) ceramic materials were successfully prepared by Flash Sintering (FS) under an electric field of 550 V cm−1 at 1200 °C for 18 min. The influences of different ionic radius on flash sintering behavior, crystal structure, microstructure and dielectric properties of TiO2-based colossal permittivity (CP) ceramics were systematically investigated. FS can reduce the sintering temperature by 200 °C and shorten the sintering time by more than 12 times. The results show that all flash sintering samples were pure rutile TiO2 structure. The grain size decreased with increasing ionic radius. ATTO had the lowest dielectric loss of 0.2 and ITTO had a maximum dielectric constant of 8100 at 1 kHz. XPS analysis confirms that Ti3+ content increased gradually with increasing ion radius. Impedance spectroscopy analysis shows that all flash sintering ceramics were composed of semi-conductive grains and insulating grain boundaries. The CP behavior was explained using the internal barrier layer capacitance effect. This work provides a very meaningful method for the preparation of co-doped TiO2 CP ceramic materials.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2023
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IF 7.2
Huang Xu,Huihu Wang,Ziguan Zhang,Hao Tu,Jian Xiong,Xing Xiang,Chenhuinan Wei,Yogendra Kumar Mishra
In this study, a series of multicomponent Al-based composites were prepared by mechanical ball milling of Al powder , low-melting-point metals (Ga, In, Sn), NaCl , g-C 3 N 4 and carbon nanospheres . The composites were thoroughly analyzed using state-of-art characterization techniques with respect to morphologies, structures, chemical compositions , thermal, and electrochemical properties , etc. The hydrogen production performance of Al-based composites has been investigated under three low-temperature conditions, including deionized water (275.15 K), snow-melting agent aqueous solution (253.15–273.15 K), and aqueous electrolyte solutions (KOH, FeCl 3 , CaCl 2 , ethylene glycol) at 233.15 K. The best hydrogen production performance with a hydrogen yield of 1133 mL·gAl −1 at 275.15 K and 1095 mL·gAl −1 at 253.15 K was obtained. Especially, no induction time was observed in either condition. Even at 233.15 K in KOH solution, its reaction induction time was around 6 s and final hydrogen yield reached 1057 mL·gAl −1 . The observed hydrogen production capabilities of composites have been analyzed and understood in depth, and a tentative multicomponent activation mechanism for low-temperature hydrogen production was proposed as well.
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Frontiers in Chemistry
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2023
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IF 5.5
Gao Bingliang,Liu Zhiwei,Deng Yifan
Al-Li alloy was prepared by electrodeposition on solid aluminum electrode in a urea-LiCl (77.5:22.5, mol%) molten salt system at 353–393 K. The results of cyclic voltammetry and chronopotentiometry show that underpotential deposition of Li occurs on the Al electrode and forms phases of Al(α) and AlLi(δ) which are confirmed by XRD measurements. Scanning electron microscopy observation of deposits indicates that Al-Li alloy with the thickness of 143 µm was obtained by potentiostatic electrolysis at −0.5 V vs. Li+/Li. The Li content in the alloy obtained at 373 K can reach 6.9 wt%. Galvanostatic electrolysis at 20 A demonstrated that Al-Li alloy coating on aluminum plate can be obtained from urea-LiCl electrolyte at 373 K in the atmosphere.
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PubMed
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JOURNAL OF MATERIALS SCIENCE
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2023
·Vol. 58
·期 23
·9446-9458
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IF 4.5
Cheng Zhipeng,Yin Jingzhou,Chu Xiaozhong,Yang Tingting,Gao Yuan,Zhong Hui,Zhang Lili
Transition metals (TMs) have an excellent catalytic effect on the thermal decomposition of ammonium perchlorate (AP). However, nanosized TM catalysts tend to agglomerate due to their high surface energy and magnetism. In this work, a new Fe/Al composite catalyst was synthesized by loading Fe nanoparticles onto Al powder through a facile replacement route, and its effect on the thermal decomposition stability of AP and AP-based propellants was investigated. Morphological and structural characterization showed that Fe nanoparticles were successfully decorated on the Al surface without noticeable aggregation or shedding. The diameter of Fe nanoparticles was approximately 10 nm. The constructed Fe/Al composite catalyst presented a strawberry-like structure. Elemental mapping analysis revealed that the dispersion state of the Fe/Al composite catalyst was better than that of commercial Fe nanoparticles with AP. Thermal analysis indicated that the Fe/Al composite catalyst presented excellent catalytic stability in the high-temperature decomposition (HTD) of AP, reducing the HTD temperature by approximately 100 °C. Burning tests showed that the relative standard deviations of the burning rate with the Fe/Al composite catalyst were 2.5 and 2.2% at 5 and 10 MPa, respectively, whereas those with Fe reached 17.1 and 13.9% at 5 and 10 MPa, respectively. The Fe/Al composite catalyst inherited the good dispersion of Al, effectively resolving the problems of Fe nanocatalyst agglomeration. Therefore, the as-obtained Fe/Al composite catalyst can significantly improve the thermal decomposition stability of AP and AP-based propellants and will have wide application prospects in the field of AP-based propellants.
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ACS Sustainable Chemistry & Engineering
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2023
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IF 8.4
Shiyao Lu,Jian Zhang,Hao Meng,Xiaoyuan Qin,Jianbin Huang,Yehao Liang,Feng-Shou Xiao
Dehydration of methyl lactate (ML) obtained from biomass is a sustainable route for the production of methyl acrylate (MA). Herein, we demonstrate that cesium-exchanged Al-rich Beta zeolite (Cs-Beta) is highly efficient for the dehydration of ML to MA, exhibiting full ML conversion with 87.4% MA yield at 340 °C. In situ FT-IR spectra and kinetic studies provide evidence that the ML dehydration on the Cs-Beta zeolite follows a forward ion-exchange/dehydration/reverse ion-exchange reaction pathway. Model experiments, DFT calculations, TG-DSC analysis, and FT-IR spectra showed that coke formation competes with the dehydration of ML to MA. Kinetic studies and theoretical simulations demonstrate that cesium cations in the micropores of Beta zeolite have a strong steric hindrance, suppressing the formation of oligomers and coke. These results offer new insights for developing highly selective and stable catalysts for the dehydration of ML to MA in the future.
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CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Jiankan Zhang,Fengqi Zhao,Hui Li,Zhifeng Yuan,Ming Zhang,Yanjing Yang,Qing Pei,Ying Wang,Xueli Chen,Zhao Qin
Micron-sized aluminum particles tend to melt into agglomerates, leading to incomplete combustion, two-phase flow losses, and energy decrease of propellants. The higher ignition performance of core–shell Al@Ni makes it a promising candidate fuel with high combustion efficiency. However, little work has been done to study the combustion of Al@Ni in propellants. Here, we report a first attempt to investigate the combustion mechanism of core–shell Al@Ni in the double-based propellant containing high energy explosive HMX , and evaluate its potential as a fuel. Nickel in Al@Ni is determined to play a critical role during its intrinsic combustion and the combustion in propellants. In the condensed phase, the presence of Ni enhances the oxidation process by forming a porous oxide layer on the aluminum surface that promotes oxygen diffusion. Subsequently the phase transition and expansion of Ni break down this oxide layer, leading to the earlier ignition on the burning surface. Upon Al melting, the alloying of Ni and Al accelerates the volume expansion and surface tension reduction of the fuel, giving rise to vigorous melt-dispersion combustion and enhanced energy release. Enhanced thermal feedback and thermal decomposition exotherm combined to increase the burning rate of propellant. The resulting higher flame temperature allows the evaporation of small aluminum droplets into vapor to form smoke oxide productions, further reducing the size distribution of the condensed combustion products (CCPs). This study demonstrates the potential of Al@Ni as an effective fuel for double-based propellants, and provides the insight into its combustion mechanism in HMX-CMDB propellants, which is believed to be important for the development of novel aluminum-based fuels for solid propellants.
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ACS Applied Nano Materials
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2023
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IF 5.9
Yuxiang Li,Iftikhar Hussain,Xi Chen,Lei Zhang,Ruishan Han,Xiaoxia Ma,Kaili Zhang
Nanothermites have high energy densities and fast reaction speeds, but their applications are restrained by their relatively low gas generation capacity owing to the lack of gaseous products. By contrast, nitrogen-rich explosives can release substantial small-molecule gases upon intramolecular decomposition. Recently, the integration of nanothermites with nitrogen-rich explosives has attracted growing interest to attain improved reactive performances. In this work, hybrid energetic composites composed of Al/CuO nanothermites and tetraamminecopper perchlorate (TACP) were prepared. The reaction behaviors of pure TACP and a series of Al/CuO/TACP composites were systematically investigated. During the dynamic heating in thermogravimetry coupled with differential scanning calorimetry (TG-DSC), the total heat release of Al/CuO/TACP composites was basically the linear combination of Al/CuO (2.23 kJ/g) and TACP (1.44 kJ/g) based on their mass contents. However, the addition of n-Al and n-CuO could lower the decomposition temperature of TACP by 20 °C, and the chlorides produced from TACP decomposition were found to promote the oxidation of n-Al. Compared with sole Al/CuO and sole TACP, the hybrid composites with TACP content of 10–25% showed considerably strengthened blast performances and significantly enhanced gas generation capacities. The maximum pressure and pressurization rate of Al/CuO/TACP_25% (1.67 MPa, 199.3 MPa/s) far exceed those of Al/CuO (1.01 MPa, 93.3 MPa/s). Owing to their superior reactivity, Al/CuO/TACP hybrid composites show promising potential as high-performance energetic materials for applications, including green primary explosives and gas generators.
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CATALYSIS COMMUNICATIONS
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2023
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IF 3.7
Li Guo,Jialing Chen,Shaokang He,Tingyu Liang,Lijun Lu,Shenke Zheng,Xinyue Hu,Lan Yi,Xiaoqin Wu
The [Fe, Al]-FER zeolites, which are prepared from the interzeolite conversion method (from MWW to FER topology) with high Al and Fe content (Si/Al of 8–18 and Si/Fe of 11–13), exhibit excellent catalytic performances and hydrothermal tolerance for NH 3 -SCR reaction. The interzeolite conversion process can be tuned by optimizing the zeolite synthesis conditions such as synthesis gel composition, crystallization time, crystallization temperature, and adding MWW seeds. The work can provide a new strategy to synthesize high Al and Fe content zeolite with high hydrothermal stability for NO x removal.
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CERAMICS INTERNATIONAL
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2022
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IF 5.532
Zetan Liu,Jingkun Xu,Xiaoqing Xi,Weijia Luo,Ji Zhou
Since the synthesis of non-oxidized ceramic and alloy powders requires both high temperature and oxygen insulation conditions, here we demonstrate a cost-efficient molten salt sealing/shielded synthesis method with dynamic gas tightness. Compared to conventional synthesis method, it can prevent the loss of reaction materials at high temperature, cut off the connection between reacting material and outside air, and does not require long-time ball milling mixing treatment or provision of applied pressing before or during heating. Only low-cost salts (e.g., NaCl, KCl), a few minutes of raw material mixing, and regular heating molds are required to obtain high-purity (>96 wt%), micron-sized Ti 3 AlC 2 and Ti 3 SiC 2 powders with narrow size distribution, which significantly decreased the complexity and production costs in the synthesis process. The effect of temperature and raw material content on the products were investigated. The mechanism of diffusion reaction between reactants in molten salt environment was analyzed. The new method developed here was also applicable to Ti 2 AlC, V 2 AlC and Cr 2 AlC MAX phases, as well as provided new ideas for the preparation of other MXenes precursors with certain stoichiometric ratios, air-sensitive materials and nanopowders .
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COMPOSITES PART B-ENGINEERING
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2022
·
IF 11.322
Fucheng Wang,Jinfeng Zhang,Kaixin Sun,Liwei Quan,Jing Wang,Naiqin Zhao,Chunsheng Shi,Shijian Zheng
Interfacial bonding is an important factor affecting the mechanical properties of composites. The interface between the in-situ synthesized ceramic phase and the metal matrix is considered ideal, so little attention is paid to the interfacial modification. In this work, we found that interfacial segregation affects the growth of the MgAlB 4 whisker and the interface of reinforcement and matrix in the composites. Systematic experiments and theoretical calculations indicate Fe solute prefer to segregate at the MgAlB 4 - { 10 1 ‾ 0 } /Al interfaces in in-situ synthesized MgAlB 4 /Al composites, which is helpful to reduce system free energy. On the one hand, Fe segregation induces the whisker coarsening and the formation of planar defects with a sandwich structure formed by a layer of Fe atoms and two layers of Al atoms in coarse-whiskers, on the other hand, it improves the interfacial strength . Although extra Fe aggravates the whisker coarsening, the synergistic reinforcing effect of the whiskers and the extra Fe is greater than the sum of their individual reinforcing effects. This work demonstrates that interfacial segregation can be used to modulate the size of reinforcements and improve interfacial strength.
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EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
·
2022
·Vol. 124
·期 9
·2100254
·
IF 3.196
Kainan Xing,Minghe Cao,Qinkai Zhu,Haojie Yin,Meizhen Lu,Jianbing Ji
Vegetable oils and their derivatives are of great interest because of their abundance and renewability. This paper prepares nonanal (N) and methyl 9-oxonanoate (M) from methyl epoxystearate (ME) with WO 3 ∙0.33H 2 O, WO 3 ∙H 2 O, and WO 3 ∙2H 2 O as catalysts and H 2 O 2 as the oxidant without the use of organic solvent. The reaction temperature, catalyst amount, H 2 O 2 amount, and reaction time effects on ME conversion and N/M yield are investigated. The results show that WO 3 ∙H 2 O has the best catalytic performance. The optimal reaction conditions are: reaction temperature 60 °C, reaction time 40 min, ME/H 2 O 2 /WO 3 ∙H 2 O molar ratio 1/1.2/0.4, under which the ME conversion and N/M yield reach 95% and 70%, respectively. WO 3 ∙ n H 2 O reacts with H 2 O 2 to form soluble tungsten anions, resulting in severe tungsten loss. Al-MCM-41 materials with different silicon to aluminum molar ratios are added to the reaction system as adsorbents to recover the catalyst by effective adsorption of tungsten anions. The adsorption performance improves as the Si/Al ratio decreases, however, the ME conversion and N/M yield decrease. Thus, 50 is the most suitable Si/Al ratio. The ME conversion and N/M yield can still reach 90% and 60% after four times of use. Practical applications : The nonanal has a natural fragrance and can be used in the cosmetic industry as well as in the preparation of bio-based surfactants. The methyl 9-oxonanoate can be converted into polymer monomers by hydrogenation or amination. The results show that WO 3 ∙ n H 2 O has good catalytic activity, and a satisfying yield of aldehyde products is obtained under mild reaction conditions.
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