RESEARCH ON CHEMICAL INTERMEDIATES
·
2018
·Vol. 44
·期 5
·3135-3150
·
IF 1.674
Wang Cheng-zhi,Zhao Yong-gang,Zhang Cheng,Yan Xin,Cao Peng
Honeycomb cordierite-based Mn–Ce/Al 2 O 3 (Mn–Ce/Al 2 O 3 –C) and Fe–Mn–Ce/Al 2 O 3 (Fe–Mn–Ce/Al 2 O 3 –C) catalysts were prepared by an impregnation method and investigated in low-temperature selective catalytic reduction (SCR) of NO with NH 3 at 100 °C. The Fe–Mn–Ce/Al 2 O 3 –C catalyst exhibited not only higher catalytic activity, but also much better SO 2 and H 2 O resistance in the presence of 30 ppm SO 2 and/or 5 vol% H 2 O than Mn–Ce/Al 2 O 3 –C. After doping Fe, the NO conversion of Mn–Ce/Al 2 O 3 –C catalyst displayed an increasing trend from 79 to 84% in the absence of SO 2 and H 2 O at 100 °C under a gas hour space velocity of 1667 h −1 . The results of characterization indicated that addition of Fe was advantageous to increase BET surface area, pore volume and inhibit loss of surface Mn and Ce species. Additionally, it was helpful for generating higher concentration of Mn 4+ , more chemisorbed oxygen and more uniform dispersion of amorphous Mn and Ce in the surface of catalyst, which were beneficial to interact with reactants. Furthermore, in contrast to Mn–Ce/Al 2 O 3 –C, the SCR activity of Fe–Mn–Ce/Al 2 O 3 –C catalyst in the presence of H 2 O, SO 2 and H 2 O and SO 2 were 79, 75 and 64%, with the increase of 14, 18 and 19%, respectively. It is indicated that the addition of Fe could inhibit sulfate formation and thus enhance SO 2 resistance. XPS results reveal that the doping of Fe into the ceria lattice led to some Ce 4+ transferred into Ce 3+ in order to maintain the electrical neutrality, thereby facilitating the reduction of Ce 4+ → Ce 3+ and the formation of oxygen vacancies. NH 3 temperature-programmed desorption (TPD) results imply that the doping of Fe onto Mn–Ce/Al 2 O 3 –C can remarkably improve the distribution and concentration of acid sites. All the above factors contributed to the improvement of overall NH 3 SCR performance of the Fe–Mn–Ce/Al 2 O 3 –C catalyst compared with that of the Mn–Ce/Al 2 O 3 –C catalyst.
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高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2018
·
IF 5.16
Wancong Bian,Tong Yao,Ming Chen,Cheng Zhang,Tao Shao,Ying Yang
Epoxy resin has been widely used in electrical and electronics industries due to its excellent adhesion and insulating properties. However, the low thermal conductivity limits its application in the devices, especially under the working conditions of high frequency. In this work, the epoxy resin composites filled with binary fillers of dopamine modified micro-BN and KH550 modified nano-Al 2 O 3 were fabricated and the thermal conductivities, dielectric losses and breakdown strengths in high frequency and electrical field of the composites were studied. A high thermal conductivity of 1.182 W m −1 K −1 was realized in the composite with 22.5 wt% BN and 7.5 wt% Al 2 O 3 , which was about 700% higher than neat epoxy resin. The results of breakdown experiments in high frequency and high voltage field showed that the positive effect of the thermal conductivity increase was greater than the negative effect of the dielectric loss increase, and the notably improved breakdown time of the composite was 406% higher than that of neat epoxy. The epoxy resin composites with high thermal conductivity and excellent dielectric strength could be a potential insulating material in the electrical and electronics industries.
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高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Ruonan Ji,Minyu Ma,Yuntao He,Chenxu Liu,Tao Fang,Zhan Zhang,Yi Wang,Yedong He,Junsheng Wu
In this study, we explored the phase compositions and morphologies of the ceramic coatings from different aluminum sources (aluminum isopropoxide, aluminum nitrate, or a mixture of the two) prepared using cathode plasma electrolytic deposition (CPED) onto AZ31 magnesium alloys . Scanning electron microscopy and X-ray diffraction analyses of these coatings indicate that the deposited ceramic made from aluminum isopropoxide was composed of γ-Al 2 O 3 whereas the one made from aluminum nitrate was composed of MgA1 2 O 4 , and that the former was more compact and uniform than the latter. A composite coating was prepared using epoxy resin as a protective layer that sealed the micropores on the CPED coating, thereby further improving its anticorrosion property. The elemental distribution of the cross-section of the composite coating was examined via energy dispersive spectroscopy. Corrosion resistance was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy in a 3.5 wt% NaCl medium, and a salt spray test. The results indicate that the corrosion protection property of the Al 2 O 3 /epoxy resin coating of the magnesium alloy was better than that of the single Al 2 O 3 coating. A cross-cut test revealed that the adhesion of the Al 2 O 3 /epoxy resin composite coating to the magnesium alloy surface was better than that of the single epoxy resin coating. The approach presented herein provides an attractive way to modify the surface of magnesium alloys to improve anticorrosion.
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高影响因子
Energy Technology
·
2018
·Vol. 7
·期 3
·1800747
·
IF 3.175
Pengjing Chen,Longang Tao,Jian Zhu,Guofeng Zhao,Ye Liu,Yong Lu
Indium oxide is as a promising catalyst for the hydrogenation of CO 2 to methanol. Previous studies mainly focused on the cubic-phase In 2 O 3 (C-In 2 O 3 ), but the hexagonal-phase In 2 O 3 (H-In 2 O 3 ) with a corundum structure has been rarely studied because of the difficulty in its synthesis. Herein, the morphology-controllable H-In 2 O 3 in situ structured onto a thin-felt Al 2 O 3 /Al-fiber is prepared by a facile mixed solvothermal method. The amount of H-In 2 O 3 is strongly dependent on the urea/In molar ratio during the mixed solvothermal synthesis. The optimal catalyst obtained at a urea/In ratio of 4.5 possesses the highest amounts of oxygen vacancy and strong basic site. Such catalyst achieves a turnover frequency of 47.8 h −1 (the number of CO 2 converted into methanol per oxygen vacancy site per hour) and is stable for at least 200 h, being capable of converting 4.4% CO 2 into methanol at a selectivity of 67.6% at 325 °C (or higher selectivity at the expense of conversion below 325 °C) with a methanol space time yield of 0.20 g MeOH g cat −1 h −1 . In contrast, the microfibrous-structured C-In 2 O 3 (prepared by the incipient wetness impregnation method) delivers a very low methanol selectivity of only 36.8% under identical reaction conditions. In situ Fourier transform infrared spectroscopy experiments reveal that the H-In 2 O 3 /Al 2 O 3 /Al-fiber catalyzes CO 2 -to-methanol conversion through formate intermediates.
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高影响因子
CATALYSIS LETTERS
·
2014
·Vol. 144
·期 7
·1188-1196
·
IF 2.291
Zhu Lihua,Cao Maohong,Zhou Hua,Zhang Nuowei,Zheng Jinbao,Li Yunhua,Chen Bing H.
Abstract
A series of CaO/Al 2 O 3 base catalysts with different crystal phases is prepared via thermal treatment. The as-prepared base catalysts are tested through Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone in liquid-phase using a mixture of aqueous hydrogen peroxide and benzonitrile as oxidant. The corresponding results show that the CaO/Al 2 O 3 catalysts with high thermal treatment temperature (e.g. 900 °C) exhibit excellent activity as well as stability. Upon these, the catalysts are characterized by TG–DTG, XRD, N 2 -physisorption, SEM and CO 2 -TPD techniques. The characterization results clearly suggest that such a stable and efficient catalytic performance is beneficial from the formation of calcium aluminate phase, thus overcoming one of base catalyst application barriers, that Ca or CaO species loss (leach) from CaO-based catalysts during reactions. Correspondingly, it can be inferred that the treatment of the catalysts at different temperatures results in the diverse distribution of basic strength. Furthermore, it is also demonstrated that the suitable base strength (medium strength is good for the reaction selected in the work) plays a critically role in the improvement of catalytic performance. Finally, the effects of operation conditions on catalytic activity and product selectivity are also determined and discussed. Graphical Abstract
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Catalysis Science & Technology
·
2024
·Vol. 14
·期 10
·2929-2939
·
IF 4.4
Qian Xu,Zhihong Zheng,Jinjing Luo,Zheng Lai,Jianwen Chen,Jiaxin Shang
Supported MnFeOx catalysts have been prepared using Al2O3 as the substrate and were investigated for NH3-SCR. The 20% MnFe/Al2O3 catalyst removed over 80% of NOx with an N2 selectivity exceeding 90% at temperatures between 80 and 340 °C. The results from the various characterization studies indicated that the increased activity of MnFe/Al2O3 catalysts can be primarily linked to the increased chemisorbed oxygen species and Fe3+ concentrations, greater reducibility, and higher adsorption capacity for NH3. These characteristics are the outcome of the strong interaction, larger specific surface, and abundant acidic sites. Additionally, in situ DRIFTS analysis of the reaction mechanism revealed that the E–R and L–H mechanisms were responsible for the NH3-SCR reaction over the 20% MnFe/Al2O3 catalyst.
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高影响因子
ELECTROCHIMICA ACTA
·
2025
·
IF 5.6
Yazhuang Ji,Guomin Yu,Xueying Ma,Hongfang Wang,Yinghua Li,Hui Li,Fang He,Tiebing Cui
Conventional polypropylene (PP) separators in lithium-ion batteries (LIBs) suffer from poor thermal dimensional integrity and limited flame retardancy, posing significant safety hazards. In this work, a novel phosphorus-nitrogen-based flame retardant, pentaerythritol diphosphate-1-piperazine ethanol phosphate (PDPE), was synthesized. Its molecular structure features phosphate ester groups and nitrogen-containing piperazine rings, which endow PDPE with a dual flame-retardant function: gas-phase radical quenching and condensed-phase char promotion. PDPE was then integrated with inorganic oxides (SiO 2 or Al 2 O 3 ) to fabricate organic–inorganic hybrid composite separators via a simple and scalable coating method. Meanwhile, the inorganic oxides provide thermal insulation and enhance ionic conductivity, collectively contributing to improved thermal stability and the electrochemical performance of lithium-ion batteries. Among the composites, the PA63 separator (PDPE/Al 2 O 3 ) showed outstanding fire resistance, with a 53 % reduction in peak heat release rate (PHRR) and a 36 % decrease in total heat release (THR), while the char residue increased from 4.38 % (PP) to 25.38 %. It also remained dimensionally stable at 200 ℃ and exhibited a markedly reduced self-extinguishing time. Electrochemical tests showed a discharge capacity of 169.3 mAh/g after 100 cycles at 0.5C and 145.4 mAh/g at 2C, significantly higher than the commercial PP separator (147.7 mAh/g at 0.5C and 91.5 mAh/g at 2C). These results demonstrate the potential of PDPE-based composite separators for next-generation LIBs with superior safety and electrochemical performance.
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高影响因子
FUEL PROCESSING TECHNOLOGY
·
2025
·
IF 7.7
Yi Lin,Zaixing Wang,Lina Tang,Shi Jiang,Yu Guo,Xiaoqin Liu
Ni-based catalysts supported on composite metal oxides (NiO-Al 2 O 3 , MgO-Al 2 O 3 , Co 3 O 4 -Al 2 O 3 ) were synthesized via coprecipitation followed by Ni impregnation to investigate the influence of support composition on catalyst stability in methane steam reforming. Accelerated deactivation protocols (methane decomposition, high-temperature sintering, hydrothermal oxidation) revealed hydrothermal oxidation as the primary cause of irreversible deactivation. The 10Ni/NiAl catalyst (10 wt% Ni/10 wt% NiO-Al 2 O 3 ) showed remarkable regenerability after 923 K hydrothermal treatment, fully restoring its activity. This was attributed to coexisting reduced Ni species and readily reducible NiO, facilitating rapid reactivation. Other catalysts formed thermally stable NiAl 2 O 4 , leading to permanent deactivation. Methane cracking at 973 K had negligible effect, and 10Ni/NiAl catalyst exhibited the lowest carbon deposition (17.02 %). Under extreme hydrogen purged at 1223 K, only the 10Ni/CoAl catalyst exhibited a minor activity decline. The superior stability of 10Ni/NiAl was attributed to an in situ-formed NiAl composite metal oxides during 973 K calcination, which effectively anchored Ni particles, suppressed sintering, and prevented extensive oxidation.
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高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2019
·
IF 2.683
Kai Sun,Shuai Feng,Qian Jiang,Xiaofeng Li,Yaping Li,Runhua Fan,Yan An,Jiaqi Wang
The soft magnetic composites (SMCs) with high saturation magnetic flux density ( B s ) and low core loss ( P s ) have great potential in power electronics. In this work, the insulating SiO 2 -Al 2 O 3 layer was prepared by a hydro-thermal method to coat on the surface of the carbonyl iron powders (CIPs). Then, the coated CIPs were heterogeneously distributed in the reduced iron powders (RIPs) to fabricate the intergranular insulated SMCs. The scanning electron microscope (SEM) images and elements analysis confirmed that the surface of the CIPs was covered by a thin insulating layer forming a core-shell structure, and the Si-O-Al bond was detected by FTIR spectra. The resulting samples were annealed at 450 °C in N 2 atmosphere to eliminate the residual stress and improve magnetic properties. The annealed. SMCs containing 25 wt% CIPs@SiO 2 -Al 2 O 3 have optimum magnetic properties with a low P s of 106.9 W/kg and a highly approximate B s of 1.28 T (measured at 500 Hz). Compared with the conventional SMCs, the addition of the coated CIPs can suppress the adverse effect of the nonmagnetic coating layer on magnetic properties; meanwhile, the coated CIPs distributed in the RIPs can reduce the P s . This work provides a promising approach to the development of SMCs with low hysteresis loss and optimum magnetic properties at low frequency.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Yidi Xu,Jiancheng Yu,Chuchu Ye,Zengqi Ye,Xin Zhou,Yue Huang,Ziqi Yu,Yuncang Li,Jixing Lin,Xian Tong,Cuie Wen,Jianfeng Ma,Li Zhu
The 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramic has potential dental restoration applications due to its sufficient mechanical strength, high esthetic potential, and biocompatibility. Nevertheless, the conventional clinical processing of 3Y-TZP ceramic has a significant amount of material waste, high tool wear, and the possible formation of microcracks. In this study, alumina whisker (Al 2 O 3 w)-reinforced 3Y-TZP ceramic composites were prepared using the stereolithography technology followed by sintering for dental crown applications. This study aimed to address current manufacturing defects in dental ceramics by fabricating tough, strengthened zirconia ceramics using 3D printing technology. The results indicate that the grain size and distribution homogeneity of the ZrO 2 phase, mechanical properties, and hardness of the 3Y-TZP/Al 2 O 3 w specimens were better than those of the 3Y-TZP specimen, while the relative density showed a decrease with an increase in Al 2 O 3 w contents. The 3Y-TZP/7.5 % Al 2 O 3 w composite showed the best mechanical performance with a flexural strength of ∼863.0 MPa, a Vickers hardness of ∼13.2 GPa, and a fracture toughness of ∼6.6 MPa m 1/2 , which is about 13.1 %, 9.7 % and 25.1 % higher than those of 3Y-TZP specimens. The low-temperature degradation testing revealed that the addition of the reinforcement Al 2 O 3 w improved the anti-aging properties of 3Y-TZP specimens. Further, the 3Y-TZP/Al 2 O 3 w ceramic composite samples showed good cytocompatibility with a cell viability of higher than 90 % toward L929 cells and prototyping properties.
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NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 43
·20157-20170
·
IF 3.3
Xiaojun Dai,Yan Cheng,Tingting Liu,Lingjuan Mao,Ruihua Kang,Qiang Wei,Yasong Zhou
In the process of petroleum refining, realizing the production and utilization of chemical raw materials is the common goal pursued by the petrochemical industry at present. The integration of the refining and chemical industry can not only produce clean fuel, but also meet the demand of the chemical industry for raw materials. In this study, Y zeolites with controllable crystal size and particle size were successfully prepared by simply adjusting the composition of the directing agent. Through a series of characterization, the effects of the composition change of the directing agent on the physicochemical properties of Y zeolites were investigated. Corresponding NiWS supported catalysts were prepared by using synthesized Y zeolites as supports. Taking naphthalene as the model reactant, the effects of crystal size and particle size of Y zeolites on the catalytic performance of the catalyst and on the hydrocracking of naphthalene to C6–C8 products were investigated. The results show that the preparation of small crystal Y zeolites can be realized by simply adjusting the composition of the directing agent, and the corresponding catalyst can realize the efficient production of chemical raw materials. This is expected to provide a simple, economical, feasible, and effective idea for the petrochemical industry to realize the goal of refining and chemical integration.
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JOURNAL OF NUCLEAR MATERIALS
·
2025
·
IF 3.2
Shaobo Yang,Chenxi Liang,Jiali Li,Yujie Ma,Sijie Kou,Juanli Deng,Bo Chen,Shangwu Fan
The study investigated the corrosion behavior and mechanical performance of SiC/SiC composite joints with Y 2 O 3 -Al 2 O 3 -SiO 2 (YAS) interlayers under high-temperature steam environments at 1200 °C. Under low-flow conditions, partial disruption of Si-O and Al-O bonds in the YAS glass network reduced crosslinking, forming an aluminosilicate protective layer that inhibited further corrosion. Prolonged exposure led to Y 3+ migration and accumulation, resulting in Y 2 Si 2 O 7 precipitation and growth. High-flow conditions caused a thinner glass layer, continuous longitudinal cracks, and more severe erosion and dissolution of the YAS glass due to higher steam velocity. Despite these degradations, the joints exhibited satisfactory performance, maintaining shear strengths of about 40 ± 2 MPa after 15 h of low-flow exposure and about 36 ± 5 MPa after 5 h of high-flow exposure. These findings demonstrate that YAS interlayers provide excellent corrosion resistance and mechanical stability as a sealant for nuclear-grade SiC/SiC.
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