Enhanced luminescent performance of 1,8-naphthalic anhydride-loaded bimodal mesoporous silicas modified by europium nitrate

Journal of Porous Materials - Eu(NO3)3 was selected as an enhancer to improve the performance of luminescent hybrid bimodal mesoporous silica (LHMS), and a series of LHMS-EN(x)...     

NiFeAlO4载氧体制备及煤化学链燃烧反应特性

铁基载氧体是一种具有工业应用前景的载氧体,但存在氧利用率低、在高温下易烧结等问题。虽可通过制备双金属复合载氧体或添加惰性组分改进其性能,但均存在一定缺陷。若将活性组分和惰性材料融入到一个晶体结构制备尖晶石结构载氧体,则可实现利用双金属协同作用提高载氧体活性的同时,利用Al3+提高载氧体的稳定性。采用共沉淀法和溶胶凝胶法制备了具有尖晶石结构的NiFeAlO₄载氧体,考察了制备方法、载氧体与煤质量比对NiFeAlO₄载氧体化学链燃烧特性和循环稳定性的影响,并分析了载氧体对煤转化过程的作用。结果表明,溶胶凝胶法制备的NiFeAlO₄载氧体具有更好的反应性,载氧体与煤质量比为20∶1时,碳转化率为86.7%,远高于煤单独热解时的碳转化率(34%),此时CO₂体积分数为93.6%。对反应前后NiFeAlO₄载氧体晶相结构和形貌进行分析,表明循环过程中经“还原-氧化”后生成的NiO和载氧体颗粒团聚是导致载氧体活性下降的主要原因。相较于载热作用,NiFeAlO₄载氧体在煤化学链燃烧中主要起供氧作用,其不仅会促进挥发分向煤气的转化,且NiFeAlO₄载氧体与焦炭之间也存在固-固反应,利于更多CO₂的生成。     

Improvement of coercivity and thermal stability of Nd-Fe-B sintered magnets by intergranular addition of Tb80Fe20 alloy

To improve the coercivity and temperature stability of Nd-Fe-B sintered magnets for high-temperature applications, the eutectic Tb₈₀Fe₂₀ (wt%) alloy powders were added into the Nd-Fe-B sintered magnets by intergranular method to enhance the coercivity (H_cj) and thermal stability. The microstructure, magnetic properties and thermal stability of the Nd-Fe-B magnets with different Tb₈₀Fe₂₀ contents were studied. The experimental results demonstrate that the coercivity (H_cj) of the sintered Nd-Fe-B magnet is significantly enhanced from 14.12 to 27.78 kOe, and the remanence (B_r) decreases not obviously by introducing 4 wt% Tb₈₀Fe₂₀ alloy. Meanwhile, the reversible temperature coefficients of coercivity (β) and remanence (α) of the Nd-Fe-B magnets are increased from ?0.5634%/℃ to ?0.4506%/℃ and ?0.1276%/℃ to ?0.1199%/℃ at 20–170 ℃, respectively. The Curie temperature (T_C) of the Nd-Fe-B magnet is slightly enhanced with the increase of Tb₈₀Fe₂₀ content. Moreover, the irreversible flux magnetic loss (h_irr) is obviously reduced as Tb₈₀Fe₂₀ addition increases. Further analysis of the microstructure reveals that a modified microstructure, i.e. clear and continuous RE-rich grain boundary layer, is acquired in the sintered magnets by introducing Tb₈₀Fe₂₀ alloy. The associated mechanisms on improved coercivity and thermal stability were comprehensively researched.     

高能喷丸过程中的物质转移现象

采用高能喷丸技术在铝合金表面制备出纳米晶结构层，利用金相显微镜（OM），扫描电子显微镜（SEM／EDS），透射电子显微镜（TEM）及X射线衍射仪（XRD）等设备对高能喷丸铝合金表面层的显微结构及成分进行分析。结果表明：在高能喷丸表面纳米化过程中，弹丸中的Fe，cr原子在强制机械力的作用下转移进入铝合金表面，在材料表层约30μm的深度范围内形成分布不均匀的合金化层。这可能是纳米晶体中大量界面的形成使合金元素原子能够快速扩散和偏聚的结果。     

FeS2@TiO2 nanorods as high-performance anode for sodium ion battery

Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na⁺ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS₂ nanoparticles encapsulated in biphase TiO₂ shell (FeS₂@TiO₂), is developed towards the improvement of sodium storage. The diphase TiO₂ coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS₂ caused by the Na⁺ insertion. The FeS₂ core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS₂@TiO₂ nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g^-1 at 0.2 A·g^-1 after 300 cycles, 374.9 mA·h·g^-1 at 5.0 A·g^-1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g^-1 at 10 A·g^-1). Furthermore, the synthesized FeS₂@TiO₂ demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na⁺ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.     

硅烷偶联剂-树脂作软岩防崩解涂料的研究

软岩的崩解、泥化往往给工程带来困难和损失。崩解、泥化实际上是岩体失水-吸水-膨胀的过程，水在这个过程中起着关键性的作用。硅烷偶联剂一树脂涂料中由于硅烷偶联剂在岩体表面和树脂问的架桥作用，使得涂层具有吸附牢固、疏水性好的特点，起到了阻止岩体与外界水分交换、加固岩体的作用。硅烷偶联剂一树脂涂料在软岩工程方面有着广阔的应用前景。     

Oxidative Dehydrogenation of Ethylbenzene with Carbon Dioxide over Metal-Doped Titanium Oxides

Various metal-doped (Fe, V, Zr, Mg) titanium oxides were prepared by an acid-catalyzed sol–gel method and their properties as catalysts were investigated for oxidative dehydrogenation of ethylbenzene in the presence of carbon dioxide. The characterization techniques, XRD, BET, TGA were employed to analyze the features of catalyst. Fe₃Ti catalyst was found to be quite effective among the catalysts tested at 823 K, 39.8% ethylbenzene conversion and 98% styrene selectivity were acquired.     

离子交换增强玻璃表面化学稳定性的研究

系统研究了化学钢化及盐溶液后处理对Na2O-CaO-SiO2玻璃表面化学稳定性的影响。详细考察了用熔融KNO3化学钢化的玻璃以及用适当盐溶液后处理的化学钢化玻璃,在受水侵蚀后R2O的沥滤量和失重以及受碱侵蚀后SiO2的溶出量和失重。结果表明,用熔融KNO3对玻璃进行钢化处理后,玻璃的耐水性和耐碱性均有明显下降。而将化学钢化的玻璃利用适当盐溶液处理后,可以改善钢化玻璃的化学稳定性,因而可以进一步提高化学钢化玻璃的使用性能和拓展其使用范围。     

煤液化油实沸点蒸馏的模拟实验

采用TD200简易蒸馏装置对石油醚和液体石蜡进行了实沸点蒸馏，得到实沸点蒸馏数据，并绘制了实沸点蒸馏曲线和各馏分质量百分数与温度关系曲线，得出主要馏分所在的沸程分别为石油醚64．5℃～68℃，液体石蜡412℃～420℃；同时计算出了二者的平均沸点为65.73℃和404．36℃．这些曲线及数据不仅对石油醚和液体石蜡的组成和使用性能有参考价值，而且这种分析方法为煤液化油的实沸点蒸馏奠定了基础。     

Adjusting Pt Nanoparticle Size on SBA-15 by a Sol-Immobilisation Method Towards Naphthalene Hydrogenation

Regularly dispersed Pt particles on SBA-15 supported catalysts were synthesized with a Pt loading of 5 wt% by a sol-immobilisation method, wherein various Pt particle sizes within 1–5 nm were finely controlled via the adjustment of the addition amount of polyvinyl alcohol (PVA). A high PVA/Pt ratio of the initial solution tended to generate small Pt particles on the SBA-15 support due to intense protection against Pt particle aggregation. In addition, the effect of Pt particle size on naphthalene hydrogenation was investigated in terms of catalytic performance. Compared with the performance of other catalysts with Pt particle sizes greater or less than 3.5 nm, Pt nanoparticles with sizes centered at 3.5 nm exhibited excellent catalytic performance towards decalin. This excellent catalytic performance was mainly attributed to a suitable ratio of the edge sites to flat sites on these Pt nanoparticles, benefitting the rapid adsorption of naphthalene and dissociation of hydrogen.

Graphical Abstract

The Pt/SBA-15 catalysts were prepared by sol-immobilisation method. The highest performance was attributed to the Pt-nanoparticles with suitable flat/edge sites ratio.