CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Zijun Peng,Lei Yuan,Xudong Luo,Jingkun Yu,Chen Tian,Zhenli Liu
MgO–Al 2 O 3 –SiO 2 composite ceramics were prepared by spark plasma sintering (SPS). In addition, phase composition, microstructure, mechanical properties , and thermal shock properties have been systematically characterized. Introduction of Al 2 O 3 and SiO 2 significantly increased mechanical properties and thermal shock resistance of these composite ceramics. MgO–Al 2 O 3 –SiO 2 composite ceramics prepared by spark plasma sintering (SPS) exhibited fine grain size. Reduced grain size may result in extraordinary properties. Experimental results showed that MgO–Al 2 O 3 –SiO 2 composite ceramics had the highest flexural strength and hardness among all studied ceramics of 269.6 ± 9.22 MPa and 12.51 ± 0.29 GPa, respectively. Moreover, MgO–Al 2 O 3 –SiO 2 composites can reach 16 thermal cycle times. This shows that it is feasible to prepare high-performance MgO composite ceramics by SPS. Furthermore, introduction of Al 2 O 3 and SiO 2 is effective method to improve mechanical properties and thermal shock resistance of MgO composite ceramics.
研究领域:
材料科学
·
陶瓷工程
·
先进制造
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2012
·Vol. 142
·期 5
·608-614
·
IF 2.242
Zhang Shu-Guo,Yin Shuang-Feng,Wei Yu-Dan,Luo Sheng-Lian,Au Chak-Tong
Abstract We report for the first time the hydrothermal synthesis of MgO–SnO 2 solid superbase using P123 as template. The basicity of the materials was determined by two approaches of Hammett indicators method and temperature-programmed desorption using CO 2 as adsorbate (CO 2 -TPD). It was found that Mg/Sn molar ratio has an effect on MgO–SnO 2 basicity, and superbasicity was observed only at Mg/Sn molar ratio of 1. With variation of Mg/Sn molar ratio, superbase strength ( H
- ) was in the 26.5–33.0 range, showing superbasic value up to 0.939 mmol/g. The structure and texture of the as-prepared materials were studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and N 2 physio-adsorption methods. We detected particles of spherical morphology having diameter of ca . 150 nm. N 2 adsorption–desorption results suggested that the materials are of mesoporous structure, having specific surface area of 115.2 m 2 /g and average pore diameter of 6 nm. The superbase was found to exhibit excellent catalytic activity towards the one - pot synthesis of polyfunctionalized 4 H -pyrans through the condensation of aldehydes, malononitrile, and an active methylene compound. Its excellent catalytic efficiency is related to its superbasicity of the MgO–SnO 2 . The results provide a new route for the design and preparation of composite oxide superbases. Furthermore, the solid superbases will facilitate a strategy for high-efficiency synthesis of polyfunctionalized 4 H -pyrans. Graphical Abstract Novel MgO–SnO 2 solid superbase was prepared using P123 as template. Its superbase strength was in the 26.5–33.0 range, showing superbasic sites up to 0.939 mmol/g. The material is of mesoporous structure,(having specific surface area of 115.2 m 2 /g and average pore diameter of 6 nm. It was found to exhibit excellent catalytic activity towards the one-pot solvent-free synthesis of polyfunctionalized 4 H -pyrans through the condensation of aldehydes, malononitrile, and an active methylene compound. The results provide a new route for the design and preparation of composite oxide superbases.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2024
·
IF 3.5
Kai Chen,Zhenyao Qin,Mingjun Zhang,Lin Wang,Shikang Zheng,Yingtong Wang,Chuang Chen,Haoyu Tang,Yuhao Zhong,Hongxuan Yang,Guomin Wu
The repair of bone defects from various causes remains a significant challenge in clinical settings. Piezoelectric materials have been demonstrated to promote osteogenic differentiation, among which barium titanate (BT) has been widely reported. Magnesium oxide (MgO) dopants not only enhance the piezoelectric properties but also stimulate the osteogenic and angiogenic properties in stem cells. In this study, a MgO-modified BT/hydroxyapatite (MgO@BT/HA) piezoelectric ceramic scaffold was constructed using three-dimensional (3D)-printed technology. The results indicated that the addition of MgO improved the electrical properties of BT ( d 33 = 68.26 pC/N), and facilitated an increase in the proportion of HA (30%) while maintaining the piezoelectric coefficient ( d 33 = 2.04 pC/N) of the ceramic system. Furthermore, under the induction of low-intensity pulsed ultrasound (LIPUS) stimulation, in vitro biosafety experiments confirmed that MgO@BT/HA exhibits excellent biosafety and promotes the osteogenic differentiation of dental pulp stem cells (DPSCs).
研究领域:
材料科学
·
生物医学工程
·
组织工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2017
·
IF 5.951
Qiangqiang Zhu,Chun Shen,Jie Wang,Tianwei Tan
The upgrade of acetone–butanol–ethanol (ABE) mixture from biomass to high-value biofuels has aroused increasing attention. However, a reported heterogeneous catalyst, metal-containing MgAl-hydrotalcite (HT), is confronted with a serious water-resistance problem due to an inherent memory effect of HT materials. With the aim of exploring catalysts with improved water-resistance, metal-containing MgO–SiO2 catalysts were synthesized and evaluated. An investigation on the effect of metal type including Ni, Cu, Fe, Zn, and Co, metal loading, and reaction temperature on catalytic performance indicates that the 10 wt % Ni–MgO–SiO2 catalyst provides the best catalytic performance, giving a yield of 81.5% to C5–C15 ketones and alcohols at 240 °C. As expected, the catalyst exhibits an excellent water-resistance. It could tolerate up to 3 wt % water, which was much higher than 0.5 wt % over that of Cu- or Pd-HT as reported. Results from XRD and 29Si MAS NMR analyses indicate that the high water-resistance could be ascribed to the more stable structure of magnesium silicates formed in the catalyst than HT materials. For a further study of the effect of catalyst property on catalytic performance, 10 wt % Ni–SiO2, 10 wt % Ni–MgO, and 10 wt % Ni–MgO–SiO2 catalysts were investigated and characterized. Results from CO2-TPD, pyridine-IR, and NH3-TPD analyses reveal that the catalytic performance is significantly affected by an acid–base property. Obtaining a high catalytic performance necessitates a cooperation of enough acidic sites and basic sites.
研究领域:
催化化学
·
可再生资源与环境科学
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2024
·
IF 3.8
Mingwei Wang,Zhen Shi,Zhiquan Yu,Shushuang Li,Zhixin Zhang,Feng Wang
Graphical The HCHO-acetaldehyde condensation is a typic aldol reaction and a critical step to produce 1,3-propanediol from methanol and ethanol. The cross condensation of HCHO and acetaldehyde to acrolein has been conducted over MgO/SiO 2 catalyst, which shows the synergistic catalysis by the acidic sites (Mg-O-Si structure) and basic sites (Mg-O-Mg structure) for activation of HCHO and acetaldehyde, respectively. Acid-base synergistic catalysis greatly enhances the performance of MgO-based catalysts in the Aldol condensation. In this paper, the effect of acid-base strength/concentration/proportion and the synergistic catalysis on the performance of cross condensation between HCHO and acetaldehyde were studied. The NH 3 /CO 2 -TPD results indicated that the weak acidic sites combined with the medium basic sites were beneficial for the cross condensation of formaldehyde and acetaldehyde. The loading of MgO nanocrystals on SiO 2 induced the generation of new acidic sites (Mg-O-Si). Combined with the inherent basic sites (Mg-O-Mg) and Mg-O-Si, the acid-base bifunctions sites could catalyze the cross condensation of HCHO and acetaldehyde synergistically. The appropriate proportion of acidic/basic sites (10/1) was critical for the cross condensation in the presence of vast water in formalin. The effect of reaction parameters, including molar ratio of substrates, reaction temperature, linear velocity and weight hourly space velocity, were investigated for the cross condensation. The results showed that 10 wt% MgO/SiO 2 catalysts exhibited the highest catalytic activity (57.9% conversion of acetaldehyde and 84.3% selectivity of acrolein) under the optimal reaction parameters among the investigated catalysts. The catalytic performance of MgO/SiO 2 could be recovered after in situ regeneration in air to remove the carbon deposition.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ENERGY
·
2022
·
IF 11.446
Yicheng Hou,Jun Qiu,Wei Wang,Xibo He,Mubashar Ayyub,Yong Shuai
Cold compression and mixed sintering methods have attracted attention for their applicability to industrial mass production. Due to the wettability of expanded graphite (EG) and salt chlorides, the decoupling of the encapsulation effect of EG and ceramics should be considered in the form-stable composite materials ratio of ternary chlorides (TC)/MgO ceramics/EG. In this study, 40 wt%-55 wt% MgO and 5 wt%-20 wt% EG are added to the composites, respectively. It is found that the composite system can be loaded with nearly 45 wt% molten salts. The 45 wt% TC-15 wt% EG-40 wt% MgO sample named 15EG-40MgO is considered a close to optimal formulation in terms of thermal conductivity enhancement and energy density reduction. This proportional composite has a thermal conductivity of 8.86 W∙m −1 ∙K −1 , and in the temperature range of 300–600 °C, the thermal storage density reaches 439.53 J·g −1 . With the increase of TC content, the density of the composites shows a decreasing trend. However, all samples have excellent mechanical strength due to the MgO ceramics as the supporting material. Moreover, these composites can be easily integrated into a solar thermal storage system, which proposes a new strategy for applying a high-temperature packed-bed containing salt-based composite phase change materials.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Energy
·
2024
·
IF 9
Xin Zhang,Haiguang Gao,Wei Jin,Yucheng Huang,Juan Xu,Jianyu Cao
Phenazine derivatives are attractive anolyte redox-active species in aqueous redox flow batteries (ARFBs). Unfortunately, they typically suffer from sluggish reaction kinetics, resulting in poor rate capability and inferior energy efficiency, especially under high current densities . Herein, we report a composite of MgO and Ketjen black carbon (MgO/KB) that can serve as a low-cost ARFB electrocatalyst to significantly improve the redox reaction kinetics of phenazine derivatives. The MgO/KB composite catalyst exhibits excellent catalytic performance, with an area-specific resistance (ASR) of 1.54 and 1.11 Ω/cm 2 for the charge and discharge processes, respectively, as well as improved energy efficiency, capacity utilization, and durability in practical ARFB applications. Detailed research confirms that the oxygen vacancies within the MgO promote electron transfer and enhance catalytic activity for the electrochemical reaction of phenazine derivatives. Using density functional theory (DFT) calculations, we unveil that the underlying catalytic enhancement mechanism stems from a low free energy barrier of the rate-determining step (RDS) on oxygen-vacancy-enriched MgO for the oxidation reaction of dihydro-phenazine derivative. These findings will guide the design of highly active electrocatalysts for organic ARFBs.
研究领域:
材料科学
·
电化学
·
能源存储与转换
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xincheng Cai,Junjing Duan,Zhangyi Huang,Zhenyu Zhang,Shengquan Yu,Xiaoqiang Li,Jianqi Qi,Tiecheng Lu
Y 2 O 3 -MgO composites are promising for mid-infrared windows and domes in harsh environments. However, the insufficient transmittance range (the transmittance >30 % only in ∼2–7 μm) and strong absorption peak (the transmittance <32 % at 7.0 μm) of Y 2 O 3 -MgO composites severely limit their application range because of agglomerations and carbon contamination from organics in the raw materials, currently. In this study, utilizing carbon-free raw materials and high molecular motions, the reduction of carbon contamination and agglomerations within the as-synthesized nanopowers was achieved via the modified co-precipitation synthesis. A highly mid-infrared transparent (the maximum transmittance of 79 % at 6.0 μm) Y 2 O 3 -MgO composite with wide transmittance range (the transmittance >30 % in 2.2–9.7 μm) and weak absorption peaks (the transmittance ≈68.57 % at 7.0 μm) was fabricated by the hot-pressing sintering method using the as-obtained nanopowders in the absence of exogenous dopants. And the modified co-precipitation synthesis is a method with great potential for the development of mid-infrared transparent Y 2 O 3 -MgO composites with wide transmittance range and weak absorption peaks.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
WATER RESEARCH
·
2020
·
IF 9.13
Tianyu Li,Lifa Ge,Xingxing Peng,Wei Wang,Weixian Zhang
Advanced oxidation processes (AOP) based on nonradicals have attracted growing attentions because nonradical systems require much less oxidants and have low susceptibility to radical scavengers. Herein, a novel Fenton-like system that utilizes nonradicals was explored. It was derived from g-C 3 N 4 /MgO activated H 2 O 2 , and can reduce the H 2 O 2 stoichiometry from 0.94%−0.18% to 0.03%. Sulfamethoxazole (SMX), a widely used sulfonamide, was used as the model pollutant to evaluate the efficacy of the system. It was observed for the first time that organic pollutants can be degraded with singlet oxygen ( 1 O 2 ) through a nonradical pathway in the g-C 3 N 4 /MgO H 2 O 2 system. The reduced H 2 O 2 consumption was the net result of continuously-recycled H 2 O 2 from the reactions between H 2 O 2 and g-C 3 N 4 /MgO. Based on experimental results and theoretical calculations, the synthesis of g-C 3 N 4 and MgO forms a N-Mg bond with strong ability to absorb electrons and the electron transfer of H 2 O 2 to N-Mg bonding is accelerated, activation of H 2 O 2 to generate 1 O 2 . Experimental data showed that organic pollutants can be degraded rapidly over a wide pH range. Findings of this study point to a cyclical but stable Fenton-like system with reduced H 2 O 2 requirement for cost-effective remediation and treatment of organic pollutants and toxic wastes.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Tianxu Su,Bin Guan,Chunzheng Zheng,Jiefei Zhou,Zhen Huang
Developing low-temperature, high-efficiency ammonia decomposition catalysts for hydrogen production is essential for the broad application of hydrogen. This study conducted a systematic investigation of Ru/MgO catalysts modified with different alkali metals (Na, K, Cs), unveiling the impact of these modifications on catalyst performance and developing a highly efficient low-temperature ammonia decomposition catalyst. The addition of all alkali metals enhances the catalytic performance of Ru/MgO for ammonia decomposition, especially the addition of K, which results in the optimal enhancement of the catalyst, achieving a 75% ammonia decomposition efficiency at 350 °C (GHSV= 2,000 mL/h·gcat), more than doubling the performance of the unmodified Ru/MgO catalyst. The study revealed that the addition of potassium (K) altered the rate-determining step of the ammonia decomposition reaction from nitrogen recombination to the dissociation of the first hydrogen atom, and reduced the overall energy barrier required for the reaction. This facilitated the desorption of nitrogen from the Ru surface and the conversion of NH3, thereby accelerating the rate of the ammonia decomposition reaction.
研究领域:
催化
·
化学工程
·
材料科学
·
能源
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yijie Tang,Jin Wang,Junxia Wang,Long Kang,Tongming Zhang,Jun Li,Yan Wang,Xusheng Li
This paper reported the irradiation response of a 55 wt.% MgO-45 wt.% Nd 2 (Zr 1- x Ce x ) 2 O 7 (abbreviated to M-NZC x , x = 0, 0.3 and 1) composite ceramics used as candidate inert matrix fuel under 500 keV He 2+ ions with fluence of 1 × 10 16 –5 × 10 17 ions/cm 2 . The irradiation-induced lattice expansion, amorphization of MgO and NZC x phases and order-disorder transition of Nd 2 (Zr 1- x Ce x ) 2 O 7 pyrochlore were systemically explored via GIXRD, Raman and TEM techniques. And the detailed irradiation response at different depths of the typical M-NZC 0.3 sample was especially investigated via GIXRD and TEM. The results showed that the lattice expansion ratios ( Rs ) of MgO (M), ordered pyrochlore (P) and disordered defect-fluorite (F) structures of NZC x pyrochlore in the samples under the same dose of He 2+ irradiation were regular, which were ranged as the following order: Rs M < Rs P < Rs F . And there was a belt-shaped damage aggregation zone located near interphase boundary at the maximum damage depth of M-NZC 0.3 sample, which could be explained by the defect-absorption of boundary. And this defect-absorption of boundary was also found at any depth of M-NZC 0.3 sample. This work systematically analyzed α-decay irradiation response of different phases in M-NZC x composite ceramics applying for inert matrix fuel.
研究领域:
核材料科学
·
辐照效应研究
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2015
·Vol. 30
·期 10
·1639-1647
·
IF 1.647
Xueming Liu,Chunge Niu,Xinping Zhen,Jide Wang,Xintai Su
A phase transfer method was developed to prepare Mg(OH)2 nanosheets and a subsequent adsorption–calcination process was followed to obtain lamellar MgO nanostructures. The as-prepared MgO nanosheets also showed a superior adsorption property of Congo red. Transmission electron microscopy and x-ray diffractometer results indicated that the as-obtained Mg(OH)2 was plate-shaped with a hexagonal crystal structure where MgO possessed a lamellar structure with a cubic phase. The maximum adsorption capacities of Mg(OH)2 and MgO were reached up to 1820 and 2650 mg g−1, respectively. The high adsorption capacity might be related to the particle geometry and large surface area (87.97 m2 g−1 for Mg(OH)2 and 132.31 m2 g−1 for MgO). The adsorbents can be easily regenerated for five times without any significant loss in their adsorption property. The adsorption behaviors of the Mg(OH)2 and MgO adsorbents showed that the adsorption kinetics and isotherms were in good agreement with pseudo-second-order rate equation and Freundlich adsorption model.
研究领域:
材料科学
·
环境科学
✓ 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）