CATALYSIS LETTERS
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2022
·Vol. 153
·期 6
·1786-1796
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IF 2.936
Zhao Wei,Zhang Hongyi,Zhang Lei,Gong Jianchao,Chen Tianen,Ren Liming,Ji Yaxiong,Meng Fanbin
The methanol oxidation reaction is a promising route to eliminating trace amount of methanol in exhaust gases which aroused serious environmental concern. In this work, a novel Pd/MgAl 2 O 4 catalyst was prepared to construct the metal-support interface and employed in the methanol oxidation reaction. The reaction results show that the Pd/MgAl 2 O 4 catalyst could achieve 100% methanol oxidation at 198 ℃ over the Pd/MgO and Pd/Al 2 O 3 catalysts. The high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), CO-chemisorption, H 2 temperature programmed reduction (H 2 -TPR), and CO diffuse reflectance infrared Fourier transformed spectroscopy (CO-DRIFTS) show that the Pd was uniformly distributed over the MgAl 2 O 4 support due to strong interaction between Pd and MgAl 2 O 4 . The mechanism studies show that the abundant Pd-MgAl 2 O 4 interfaces significantly contributed to the reaction enhancement. The Pd-MgAl 2 O 4 interfaces could greatly enhance the oxidation reaction at a lower temperature with the assistance of oxygen vacancies compared with traditional oxide catalysts, which was confirmed by methanol temperature program surface reaction (MeOH-TPSR) experiments. In-situ DRIFTS is carried out to elucidate the reaction mechanism and establish the structure − activity relationship: the methanol could be effectively absorbed on the MgAl 2 O 4 support with oxygen vacancies to form bidentate formate, then the Pd species assisted the intermediates converting to CO 2 product. The Pd/MgAl 2 O 4 catalyst and its enhancement mechanism investigation provided a potential strategy in the VOCs removal catalysis development. Graphical Abstract
研究领域:
催化化学
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环境科学
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产品关联
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
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2021
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IF 5.039
Xiao-jun Wang,Song-tong Xuan,Ming Feng,Yu-ming Tian
The in-situ formed MgAl 2 O 4 –CaAl 12 O 19 (MA–CA 6 ) composites were fabricated in this study. To clarify the influence of the evolution of CA 6 phase on the properties of MA–CA 6 composites, the sintering temperature was carried out at 1200–1700 °C for 2 h. The results show that the growth and development of CA 6 grains improves the densification and flexural strength of MA–CA 6 composites. The formation of MA phase occurs at 1200 °C, while the CA 6 phase is formed by the reaction of CaAl 4 O 7 (CA 2 ) and Al 2 O 3 appears at 1400 °C. The plate-like CA 6 grains intersect with each other, presenting regular hexagonal morphology with a high aspect ratio at 1500 °C. The CaO–Al 2 O 3 –SiO 2 phase acts as an interface phase to regulate the growth and development of MA and CA 6 grains. The CA 6 phase was crystallized from the transient liquid phase CaO–Al 2 O 3 –SiO 2 to significantly increase its thickness at 1600 °C. At the same time, as the sintering temperature rises, the apparent porosity of the sample decreases from 24% at 1400 °C to 4% at 1600 °C, and the flexural strength correspondingly increases from 96.6 MPa to 167 MPa. However, the suitable sintering temperature should not exceed 1600 °C for better properties of the composites.
研究领域:
材料科学
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陶瓷工程
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DOI
高影响因子
CERAMICS INTERNATIONAL
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2021
·
IF 4.527
Qian Wu,Guo Feng,Feng Jiang,Lifeng Miao,Weihui Jiang,Jian Liang,Jianmin Liu,Jingang Tan,Xiaojun Zhang,Xinbin Lao
Petal-like MgAl 2 O 4 spinel was successfully prepared using a novel inorganic salt-assisted nonhydrolytic sol-gel method without a template and was employed as absorbent in the removal of the Congo red (CR). The effects of the inorganic salt type, heat-treatment temperature, and dwelling time on the morphology and phase composition of the petal-like MgAl 2 O 4 spinel were investigated systematically. Results indicated that when Na 2 MoO 4 was employed as the salt and the heat-treatment temperature and dwelling time were 600 °C and 5 h, respectively, the as-obtained petal-like MgAl 2 O 4 spinel exhibited a highly uniform morphology with a thickness of 19–23 nm and a length of 240–280 nm. The N 2 adsorption-desorption results revealed that the petal-like MgAl 2 O 4 exhibited a large BET specific surface area of 161 m 2 g -1 with a pore volume of 0.24 cm 3 g -1 . The growth mechanism of the petal-like MgAl 2 O 4 is believed to be the formation of a two-dimensional layered network structure by the coordination between the condensation product of the magnesium aluminium bimetallic alkoxides and the ions in the salt. The as-prepared MgAl 2 O 4 petal exhibited an effective adsorption capacity toward anionic dyes CR. The maximum adsorption capacity of CR onto the mesoporous MgAl 2 O 4 petal was found to be 572.01 mg/g, it is showed the petal-like MgAl 2 O 4 exhibit huge potential of application in the field of environmental remediation.
研究领域:
材料科学
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环境科学
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DOI
高影响因子
Science China-Technological Sciences
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2021
·Vol. 64
·期 6
·1250-1263
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IF 3.572
Liu XiongZhang,Zhang SenJing,Luo Hui,Chen Fu,Li DongMeng,Wang Xian,Gong RongZhou
The design of the high-temperature microwave absorbing materials (MAMs) with temperature-insensitive and considerable microwave absorption (MA) capacity is a tremendous challenge. TiB 2 -Al 2 O 3 /MgAl 2 O 4 MAMs are prepared by the spark plasma sintering (SPS). Further, the influences of the Al 2 O 3 content on the flexural strength, thermal stability, high-temperature electrical conductivity, dielectric and MA properties are discussed. The results show that the Al 2 O 3 content is associated with flexural strength, high-temperature thermal stability, electrical conductivity, dielectric and MA properties. Meanwhile, the temperature-insensitive and considerable MA properties with the minimum reflection loss (RL min ) ranging from −19.4 to −14.3 dB and the effective absorption bandwidth (EAB, RL<−5 dB) of 3.19–3.55 GHz are attained at 25°C–700°C in 8.2–12.4 GHz as the Al 2 O 3 content increases from 70.6 wt% to 80.6 wt%. This is ascribed to the compensating effect of the positive and negative temperature coefficient materials on the high-temperature electrical conductivity as well as the co-play of the dipolar and interfacial polarization at elevated temperatures. Consequently, TiB 2 -Al 2 O 3 /MgAl 2 O 4 ceramics exhibit the ideal prospect as the high-temperature MAMs.
研究领域:
材料科学
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电子材料
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DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
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2019
·Vol. 55
·期 4
·1727-1737
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IF 3.442
Peng Guangchun,Qiao Qianqian,Jin Lei,Zhang Bowei,Wang Yi,Huang Kang,Yao Qiong,Zhang Dongjiu,Zhang Zhan,Fang Tao,Wu Junsheng,He Yedong
A novel CeO 2 /MgAl 2 O 4 composite coating, fabricated via a cathode plasma electrolytic deposition (CPED) technique followed by hydrothermal synthesis, was developed in this study to explore its potential application as corrosion protection for AZ31 magnesium alloys. The microstructure observed through scanning electron microscopy indicated that reducing the duty cycle of the power source within a reasonable range during the CPED process was beneficial to form a uniform and dense MgAl 2 O 4 coating, which served as an ideal adhesive matrix for a uniform CeO 2 coating as the outermost layer. The results of electrochemical impedance spectra and neutral salt spray tests showed that the decoration of the CeO 2 layer significantly improved the corrosion resistance of the CeO 2 /MgAl 2 O 4 composite coating compared to the single MgAl 2 O 4 coating and bare substrate. Cross-cut tests revealed that the adhesion of the MgAl 2 O 4 coating and the CeO 2 /MgAl 2 O 4 composite coating were both excellent due to the strong binding between the MgAl 2 O 4 coating and the substrate.
研究领域:
材料科学
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表面工程
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腐蚀与防护
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DOI
高影响因子
Energy Technology
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2020
·Vol. 8
·期 9
·2000205
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IF 3.404
Qiang Liu,Jiaming Wang,Kang An,Siran Zhang,Guilong Liu,Yuan Liu
In view of the dual active sites mechanism of direct ethanol synthesis and the excellent catalytic performance of bimetallic catalysts, a series of Ni–Fe alloy catalysts with different Ni/Fe molar ratios derived from layered double hydroxides (LDHs) precursors are synthesized. During the calcination and reduction process of LDHs precursors, the Ni–Fe alloy is obtained, and attributed to all the elements being evenly dispersed at the atomic level in the LDHs precursors; meanwhile, a strong interaction between Ni–Fe alloy and MgAl 2 O 4 support exists. As a result, Ni–Fe alloy nanoparticles are highly dispersed on the MgAl 2 O 4 surface. The high CO adsorption ability on the Ni–Fe alloy and synergism catalysis between Ni and Fe result in excellent catalytic activity and high selectivity to ethanol on the bimetallic Ni–Fe alloy. In addition, the strong antisintering ability and stable alloy structure bring about a good catalytic stability. This research proposes a new catalytic system for direct ethanol synthesis from syngas.
研究领域:
化学工程
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催化材料科学
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
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2021
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IF 5.316
Jiaji Yang,Xiongzhang Liu,Wei Gong,Tao Wang,Xian Wang,Rongzhou Gong
Developing high-temperature microwave absorption (MA) materials remains a challenge in the field of radar stealth. Here, we propose a design concept of meta-structure for temperature-insensitive and broadband MA. The three-phase TiB 2 /Al 2 O 3 /MgAl 2 O 4 composites are prepared to realize the temperature-insensitive MA properties, which is ascribed to the interaction of different components in terms of the electrical conductivity , dipolar polarization and interfacial polarization as temperature increases. On this basis, we design and fabricate a three-layer meta-structure composed of the SiO 2 ceramics as environmental adaptation layer, the patch-type and flat composites as MA layers. Compared with flat composites, the meta-structure can optimize its effective permittivity, thereby realizing enhanced MA properties at elevated temperatures. This meta-structure can realize a reflection loss (RL) less than −5 dB at 8.2–18.0 GHz in the temperature range of 25 °C to 1100 °C. The experiment matches well with the simulation. The temperature-insensitive and enhanced MA properties are attributed to the consequence of the combination of traditional absorbing materials and metamaterial structures.
研究领域:
材料科学
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电磁学
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产品关联
DOI
高影响因子
Arabian Journal of Chemistry
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2022
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IF 6.212
Qian Wu,Feng Jiang,Guo Feng,Sanhai Wang,Lifeng Miao,Weihui Jiang,Jian Liang,Jianmin Liu
MgAl 2 O 4 /C composite was prepared via a facile low-temperature non-hydrolytic sol-gel (NHSG) route, using Mg powder, Al wire and isopropanol as raw materials. The influence of types of magnesium source and heat treatment temperature on the synthesis and adsorption properties were investigated, and the adsorption mechanism was also studied. The results showed that the amorphous MgAl 2 O 4 formed at < 600 °C, and it crystallized at 700 °C. No impurity phase appeared in the samples calcined at 700–1300 °C, which was attributed to MgAl 2 O 4 crystallized directly from Mg(Al(O i Pr) 4 ) 2 . The uniform-doped carbon in MgAl 2 O 4 /C composites came in-situ from the organic groups in Mg(Al(O i Pr) 4 ) 2 . MgAl 2 O 4 /C showed a superior adsorption capacity for Congo red (CR). The bimetallic alkoxides structure was favorable for high adsorption property, and the adsorption property of amorphous MgAl 2 O 4 /C was significantly superior to that of its crystalline counterpart. The adsorption kinetics data was fitted with the pseudo-second-order model, while the Langmuir isotherm model could well descript the adsorption isotherm behavior, and the maximum adsorption capacity for CR was 5690 mg/g. The high adsorption capacity was attributed to the Lewis acid-base reaction and the electrostatic interactions between the anionic dye CR and MgAl 2 O 4 /C surface as well as the in-situ carbon, and amorphous state.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
ACS Applied Nano Materials
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2021
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IF 5.097
Yongdi Zhang,Shaowen Wu,Yuanzhi Li,An Zhang,Qianqian Hu,Jichun Wu,Xin Tan
A unique nanocomposite of Rh quasi-monolayer clusters supported on spinel MgAl2O4 nanosheets with a low Rh loading of 0.15 wt % (Rh/MgAl2O4-MC) was synthesized by a facile method. By the catalyst design, nearly all of Rh atoms are utilized like well-known surface single-atom catalysts. More importantly and surprisingly, Rh/MgAl2O4-MC shows extremely high specific reaction rates of CH4 (rCH4) and CO2 (rCO2) per mole Rh and turnover frequency (TOF) for catalytic CO2 reforming of CH4 (DRM). Its rCH4 and rCO2 are as high as 51.14 and 62.65 mol molRh–1 s–1, which are 4.7 and 4.8 times higher than those of conventional Rh nanoparticles supported on spinel MgAl2O4 nanosheets with a higher Rh loading of 0.96 wt % (Rh/MgAl2O4-NP), respectively. Its TOF values of CH4 and CO2 are as much as 53.9 and 66.1 s–1, which are 3.5 and 3.5 times higher than those of Rh/MgAl2O4-NP, respectively. Meanwhile, Rh/MgAl2O4-MC retains the excellent catalytic durability of supported nanoparticles with negligible side reaction of carbon deposition, which is in striking contrast to the prone deactivation of the single-atom catalysts of precious metals (e.g., Rh and Ru) reported. Experimental evidence and DFT calculations reveal the presence of a strong interaction between Rh quasi-monolayer clusters and MgAl2O4 for Rh/MgAl2O4-MC. The interaction not only makes energetically unstable clusters stable but also alters the reaction pathway of DRM. Compared to DRM on Rh nanoparticles, the oxidations of C* and CH* species as the rate-determining step of DRM are significantly accelerated on Rh quasi-monolayer clusters due to their activation energies being considerably reduced, thus improving intrinsic catalytic activity and inhibiting the side reaction of carbon deposition.
研究领域:
材料科学
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催化化学
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能源化学
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
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2022
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IF 8.047
Zijian Yuan,Anuj Kumar,Daojin Zhou,Junting Feng,Bin Liu,Xiaoming Sun
Even though Ni catalysts have shown promising performance in the semi-hydrogenation of ethylene, the selectivity and stability remain to be improved so that they may be used to replace expensive noble metal catalysts. Herein, an aluminate-intercalated NiMgAl-layered double hydroxide (LDH) was prepared through a facile co-precipitation approach, and then a topotactic transformation strategy was employed to convert the tailored LDH precursor to the spinel catalyst. More than 99% of the Ni/MgAl 2 O 4 catalyst's conversion was achieved toward the semi-hydrogenation of acetylene at 140 °C, with a selectivity of more than 80%. Additionally, due to high specific surface area (309 m 2 /g) with tuned acidity, this catalyst showed outstanding resistance to the deposition of carbonaceous compounds and satisfactory long-term stability during a 28 hr test. It is hoped that this study will inspire the design of supported non-noble metal materials with high activity and efficiency towards organic or organo-thermal reactions, as well as provide a basic understanding of the role and impacts of intercalated aluminates in LDH.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Fen Wang,Wei-Zhen Li,Jing-Dong Lin,Zhi-Qiang Chen,Yong Wang
Catalyst durability is one of the major problems hindering the commercialization of partial oxidation of methane (POM) for syngas production. We report that a Pt/MgAl 2 O 4 -HS catalyst with the MgAl 2 O 4 -HS support being synthesized via hydrolysis solvothermal (HS) method demonstrates high stability for POM during a 500 h life testing at 900 °C without detectable coke formation, while a Pt/MgAl 2 O 4 -CP counterpart in which MgAl 2 O 4 was prepared by an optimized co-precipitation (CP) method exhibits continuous deactivation accompanied by coking. Using a suite of characterizations incluidng BET, H 2 chemisorption, XRD, STEM, TEM, TG/DTA and TPD of NH 3 and CO 2 , we reveal that the high catalytic durability of the Pt/MgAl 2 O 4 -HS is due to the spinel surface of MgAl 2 O 4 -HS that can efficiently stabilize Pt against sintering. The Pt/MgAl 2 O 4 -CP, however, has defect Al 2 O 3 or MgO-like species on the MgAl 2 O 4 -CP surface, inhibiting its capability to stabilize Pt. We confirm that the POM reaction undergoes a combustion-reforming pathway by monitoring the temperatures and gaseous product compositions along the catalyst bed. These results provide guidance for rational design of a longevity catalyst for POM process.
研究领域:
化学工程
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催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
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2021
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IF 5.706
Jiayu Song,Shengping Wang,Yan Xu,Qingling Liu,Yujun Zhao
Poor catalytic activity and stability are primary defects of traditional Pd/Al 2 O 3 catalysts for the low-temperature methane combustion. Herein, we developed a facile way to synthesize a MgAl-LDHs derived MgAl 2 O 4 spinel with good crystalline lattice and high surface area, which was used as support of Pd-based catalysts. Catalysts with Mg/Al ratio of 1/3 presented the highest methane combustion activity. It was found the well-crystallized MgAl 2 O 4 spinel promoted the dispersion and crystallization of PdO due to the strong interaction between PdO and support, and the electrophilicity and basicity originated from Mg doping suppressed the sintering of PdO particles, leading to the excellent performance of Pd/MgAl3. Moreover, these factors also inhibited the formation of surface OH- species, therefore, improved the water resistance. Such a synthesis strategy of the Pd/Mg x Al y derived from LDHs and the roles of MgAl 2 O 4 spinel could pose some meaningful directions for developing high-efficient Pd-based catalysts for the low-temperature methane combustion.
研究领域:
催化化学
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材料科学
✓ 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）