RSC Advances
·
2015
·Vol. 5
·期 77
·63044-63049
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IF 3.84
Hualei Hu,Jinghui Lyu,Jie Cen,Qunfeng Zhang,Qingtao Wang,Wenwen Han,Jiayao Rui,Xiaonian Li
The effect of MgO and Pd modification on the catalytic performance of hierarchical porous ZSM-5 for benzene alkylation with methanol was investigated. The results indicated that the introduction of MgO could reduce the Brönsted acid sites which suppressed the side reaction of methanol to olefins and in turn effectively promoted the alkylation of benzene. However, the single modification of MgO could not completely suppress the formation of ethylbenzene and coke. Doping a small amount of Pd had a positive effect on inhibiting the generation of ethylbenzene and coke, which could be attributed to the hydrogenation of ethylene into ethane on Pd. The dual modified catalyst (MgO and Pd) exhibited high benzene conversion (56%) and xylene selectivity (39.1%), and the lowest ethylbenzene selectivity (0.13%) and coke content (0.4 wt%).
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Green Chemical Engineering
·
2024
·
IF 9.1
Yang Sun,Jianfeng Wang,Siyuan Sun,Haojia Zhong,Kexin Wei,Hongchen Liu,Qiang Wei,Yongfeng Li,Fan Yang
Pore structures in carbon materials have been referred to regulate the properties of carbon, which are meaningful for improving electro-catalytic performance. Herein, a series of Pt-based porous carbon catalysts (Pt/MPC) are synthesized, which are used in hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The coupling of template method and KOH activation is used to synthesize carbon carrier, then Pt NPs are loaded on it by NaBH 4 reduction. The well-tuned catalyst Pt/MPC (131) exhibits an overpotential of 34 mV and 23 mV at the current density of 10 mA cm -2 in 1 M KOH and 0.5 M H 2 SO 4 for HER (under 5.76 wt.% Pt load), respectively. The micropore regulated by KOH provides a high ion-accessible surface, and mesoporous formed by MgO template provide a fast channel for ion transport, which leads to great electron transport and increased exposure of Pt. Besides, the MOR activity of Pt/MPC (131) is 1932.05 mA mg -1 , which is 2.68 times higher than that of commercial 20%Pt/C (721.14 mA mg -1 ), and has half-wave potential of 0.82 V on ORR. The abundant hierarchical pores and highly utilized Pt active sites are favorable for accelerating the sluggish kinetics of HER, MOR, and ORR. This work provides an anticipated perspective of applicable Pt-based catalyst for advanced electrocatalysts.
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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.
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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.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2026
·
IF 6.3
Hongyu Ding,Yujie Yang,Zhihao Geng,Tan Hu,Shaofan Ge,Ying Tang,Xiyan Wang
The development of high-performance microwave absorbing materials for extreme environments remains a significant challenge. In this work, the microwave absorption properties of a FeCoNiCrMn high-entropy alloy (HEA) were successfully modulated through an MgO doping strategy. A series of FeCoNiCrMn-based composites with MgO doping concentrations of 0, 1, 3, and 5 wt.% were fabricated, followed by annealing at 600 °C for 60 min in a nitrogen atmosphere. Electromagnetic characterization revealed that the doping level plays a critical role in determining the absorption performance. The composite with 3 wt.% MgO exhibited the optimal performance, achieving a minimum reflection loss ( RLₘᵢₙ ) of -55.02 dB and an effective absorption bandwidth ( EAB max ) of 4.4 GHz, while the sample with 1 wt.% MgO also demonstrated excellent absorption properties. Furthermore, the annealing temperature was confirmed to be another critical parameter, as the absorption properties of samples annealed at 500, 550, 650, and 700 ℃ exhibited markedly weaker absorption performance than those annealed at 600 °C. The optimal performance arises from the coupled effect of MgO doping and annealing at 600 °C. This processing window optimizes interfacial polarization and the defect/strain state of the HEA matrix, thereby achieving a favorable balance between impedance matching and attenuation. Beyond presenting a promising HEA-based absorber, this work elucidates the critical synergy between doping and thermal processing in tailoring electromagnetic properties. The understanding of this interplay ultimately provides new insights for designing high-performance microwave-absorbing materials.
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CHEMOSPHERE
·
2023
·
IF 8.8
Hai Liang,Wanting Wang,Haiyan Liu,Xinzhong Deng,Dan Zhang,Yuxuan Zou,Xuehua Ruan
Engineering magnesium oxide (MgO)-modified biochar (MgO-biochar) with high porosity and active MgO load is a feasible pathway to enhance phosphate adsorption capacity. However, the blockage to pores caused by MgO particles is ubiquitous during the preparation, which seriously impaired the enhancement in adsorption performance. In this research, with the intent to enhance phosphate adsorption, an in-situ activation method based on Mg(NO 3 ) 2 -activated pyrolysis technology was developed to fabricate MgO-biochar adsorbents with abundant fine pores and active sites simultaneously. The SEM image revealed that the tailor-made adsorbent has well-developed porous structure and abundant fluffy MgO active sites. Its maximum phosphate adsorption capacity was coming up to 1809 mg/g. The phosphate adsorption isotherms are in accordance well with the Langmuir model. The kinetic data, which agreed with the pseudo-second-order model, indicated that chemical interaction is existing between phosphate and MgO active sites. This work verified that the phosphate adsorption mechanism on MgO-biochar was composed of protonation, electrostatic attraction, monodentate complexation and bidentate complexation. In general, the facile in-situ activation method using Mg(NO 3 ) 2 pyrolysis illuminated biochar activation with fine pores and highly efficient adsorption sites for efficient wastewater treatment .
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PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2019
·
IF 0
Sefiu A. Rasaki,Tiju Thomas,Minghui Yang
Due to high surface area and large pore volume, nanostructure zinc oxides/its composites have gained a lot of research interests for heavy metal removal from water. Low stability of the ZnO at low and high pH is however a problem. In this work, ZnO@MgO, ZnO and MgO are synthesized via co-precipitation, followed by calcinations. The samples show remarkable removal of Pb(II) from water when compared to commercial samples; the best results is obtained using ZnO@MgO which exhibit adsorption capacity of 250 mg g −1 equivalent to 100% removal capacity. The optimum removal capacity is retained in a wide range of pH (i.e. pH 6–9) at temperature 30 °C. Low adsorption capacity coupled with low stability in acidic condition; a problem associated with ZnO-based adsorbents when it is being used for the removal of heavy metals from water/wastewater; often prevents this system from being practically used; is overcome here. The ZnO@MgO adsorbent shows chemical stability over wide range of pH(2–9). The adsorption is chemisorptive in nature, endothermic and evidently aided by high surface heterogeneity (△H° ˜25 kJ mol-1 and △S°˜110.6 J mol −1 K −1 ). Appreciable adsorption capacity over wide range of pH-value, high recovery and reusability results from nanosphere morphology of the composite sample; all these novel properties are attributed to the strong electronic coupling effect between MgO and ZnO. This work is expected to spur further research on ZnO-based composite materials in allied areas, including (i) mitigation of atmospheric pollution and (ii) water treatment processes.
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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.
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CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
An-Nan Chen,Jia-Min Wu,Huan Xiao,Jing-Yan Chen,Xiao-Yan Zhang,Fen Chen,Yi-Xin Ma,Chen-Hui Li,Qing-Song Wei,Yu-Sheng Shi
A novel rapid, uniform and non-contamination in-situ solidification method for alumina suspension by DCC-HVCI method using MgO sintering additive as coagulating agent was reported. MgO was used to release Mg 2+ in suspensions via reaction with acetic acid generated from glycerol diacetate (GDA) at elevated temperature as well as to improve density and suppress grain growth of alumina ceramics during sintering. Influence of adding 0.7 wt% MgO with 2.0 vol% GDA in alumina suspension on coagulation process and properties of green bodies and sintered samples were investigated. It was indicated that the controlled coagulation of the suspension could be achieved after treating at 70 °C for 10 min. Homogeneous composition distribution of Mg element in EDS result indicated the uniform solidification of suspensions. Compressive strength of wet-coagulated bodies is 2.09±0.25 MPa. Dense alumina ceramics with relative density of 99.2% and flexural strength of 354±16 MPa sintered at 1650 °C for 4 h present homogeneous microstructure. The result indicated that the novel DCC-HVCI method via a sintering additive reaction with no contamination, short coagulation time and uniform in-situ solidification is a promising colloidal forming method for preparing high-performance ceramic components with complex shape.
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MINERALS ENGINEERING
·
2024
·
IF 4.9
Shurong Shi,Lihua Gao,Junhong Zhang,Zhijun He
A systematic study of the preparation and metallurgical properties of magnesia flux pellets was used to elucidate the mechanism for oxidation and consolidation occurring during oxidative roasting. The compressive strength of the finished pellets was 3545 N/P. With sufficient basicity and MgO contents, magnetite (Fe) x [Fe] 2 O 4 and maghemite γ-Fe 2 O 3 with spinel-type crystal structures combined with MgO/CaO to form nonstoichiometric Mg x Fe 1-x Fe 2 O 4 (0 < x < 1) and Ca y Fe 1-y Fe 2 O 4 (0 < y < 1). With higher basicity and MgO contents, the participation of CaO/MgO was the driving force for gradient conversion from olivine Fe 2 SiO 4 to olivine Mg x Ca 2-x SiO 4 . The CaO/MgO combined with magnetite (Fe) x [Fe] 2 O 4 and maghemite γ-Fe 2 O 3 to form stable (Ca, Mg) x Fe 1-x Fe 2 O 4 , CaFe 2 O 4 and CaFe 3 O 5 , thereby inhibiting recrystallization of the pellets and resulting in poorer metallurgical properties of the magnesia flux pellets.
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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.
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OPTICS AND LASER TECHNOLOGY
·
2025
·
IF 5
Mengxing Ge,Maimaitijiang Mamuti,Deqiao Xie,Yun Ye,Youwen Yang,Huixin Liang,Yang Liu,Xinghai Ning,Zongjun Tian
In recent years, additive manufacturing of biodegradable composite ceramics has attracted widespread attention. This study explores the vat photopolymerization (VP) of Ca 3 (PO 4 ) 2 / MgO composite ceramics, investigating the VP slurry and the effects of material composition and light-curing parameters on the monolayer curing depth and excess curing width of the green body. When the curing parameters are consistent, the monolayer curing depth of the Ca 3 (PO 4 ) 2 group, composite group, and MgO group samples decreases successively. Whereas, the excess curing width sequentially increases. When the material is the same and the exposure energy is constant, the impact of exposure time on monolayer curing depth is higher than that of exposure intensity. Regarding excess curing width, the situation is completely reversed. This research serves as a reference for the development of composite ceramic slurries and the process of photopolymerization, providing theoretical guidance for controlling the precision of subsequent photopolymerization shaping.
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