Preparation of nano-sized cerium and titanium pyrophosphates via solid-state reaction at room temperature

Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 （with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0） were obtained by grinding a mixture of Ce（SO4）2·4H2O, Ti（SO4）2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy （UV-vis）, thermogravimetry and differential thermal analyses （TG/DTA）, X-ray powder diffraction （XRD）, and transmission electron microscopy （TEM）. The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.

Application-oriented hydrolysis reaction system of solid-state hydrogen storage materials for high energy density target:A review

Hydrogen storage and delivery technology is still a bottleneck in the hydrogen industry chain.Among all kinds of hydrogen storage methods,light-weight solid-state hydrogen storage(LSHS)materials could become promising due to its intrinsic high hydrogen capacity.Hydrolysis reaction of LSHS materials occurs at moderate conditions,indicating the potential for portable applications.At present,most of review work focuses on the improvement of material performance,especially the catalysts design.This part is important,but the others,such as operation modes,are also vital to to make full use of material potential in the practical applications.Different operation modes of hydrolysis reaction have an impact on hydrogen capacity to various degrees.For example,hydrolysis in solution would decrease the hydrogen capacity of hydrogen generator to a low value due to the excessive water participating in the reaction.Therefore,application-oriented operation modes could become a key problem for hydrolysis reaction of LSHS materials.In this paper,the operation modes of hydrolysis reaction and their practical applications are mainly reviewed.The implements of each operation mode are discussed and compared in detail to determine the suitable one for practical applications with the requirement of high energy density.The current challenges and future directions are also discussed.

High Temperature Chemical Reaction of La_2O_3 in H_3BO_3-C System

The high temperature chemical reaction process of La2O3 in H3BO3-C system was studied by means of XRD and TG-DTA.The results showed that dehydration reaction of H3BO3 occurred in the temperature range of 82～390 ℃;La2O3 and B2O3 reacted to form LaB3O6,LaBO3,and B4C in the temperature range of 836～1400℃;at 1450 ℃,B4C and LaBO3 further reacted to form LaB4,and partial LaB4 and B reacted to form LaB6;at 1500 ℃,LaB4 and B reacting into LaB6 was the main reaction,and the content of LaB6 increased with prolonging time.

Microstructural evolution of NiFe_2O_4-10NiO powder prepared by high temperature solid state reaction

The NiFe2O4-10NiO powder for inert anode of aluminium electrolysis was prepared by high temperature solid state reaction. The microstructural evolution from the raw materials NiO and Fe2O3 to the NiFe2O4-10NiO powder was studied by SEM. The results show that the domain structure making up of the agglomerate particles of Fe2O3 remains after high temperature solid state reaction, and the diffusion of Ni2+ into Fe2O3 structure is the control step of the reaction process. A microstructure with compact structure and fine grain inside the particle results from the sintering of NiFe2O4-10NiO powder.

Preparing Nano-ZnS by Solid State Reaction at Room Temperature

ZnS nanoparticles were prepared by using solid-state reaction method at room temperature in agate mortar for the first time. The average particle size was about 20nm. This reaction is affected by the structure of reactant, crystal water and defects.

Characteristics of single petcoke particle during the gasification process at high temperatures

Particle concentration significantly affected the gasification of petcoke particles according to our previous studies.In this work,gasification characteristics and morphological evolution of single petcoke particle were investigated using a high temperature stage microscope experimental setup.The results showed that the reaction temperature significantly affected the reactivity of petcoke in the temperature range of 1200–1300°C.While the promoting effect on gasification reactivity decreased with further increasing the reaction temperature,the SEM analysis demonstrated the pore development during the gasification process,which attributed to the increase of reaction rate with conversion.The Raman analysis,HRTEM and SEM–EDX analysis showed that the heterogeneous graphitization of petcoke and non-uniform distribution of catalytic elements in petcoke attributed to the development of surface pores with limited depth.The gasification mechanism of petcoke particle can be briefly described as the reaction rate mainly contributed from the fast-reaction area.Besides,the pore development in fast-reaction area also enlarged the surface area of petcoke particle.

Enhanced Acid/Base Catalysis in High Temperature Liquid Water

Two novel and environmentally benign solvent systems, organic acids-ennchea high temperature liquid water （HTLW） and NH3-enriched HTLW, were developed, which can enhance the reaction rate of acid/base-catalyzed organic reactions in HTLW. We investigated the decomposition of fructose in organic acids-enriched HTLW, hydrolysis of cinnamaldehyde and aldol condensation of phenylaldehyde with acetaldehyde in NH3-enriched HTLW. The experimental results demonstrated that organic acids-enriched or NH3-enriched HTLW can greatly accelerate acid/base-catalyzed organic reactions in HTLW.

Kinetics of Non-catalyzed Decomposition of D-xylose in High Temperature Liquid Water

高温度液体水(HTLW ) 里的木糖和它的分解产品糠醛的非催化的分解的动力学从 180 ～ 220 ° C 并且在 10MPa 的压力下面为温度被学习。木糖分解的主要产品是糠醛和蚁的酸，并且糠醛进一步在 HTLW 状况下面降级了到蚁的酸。与第一个顺序动力学方程的假设，木糖和糠醛分解的评估激活精力是 123.27kJ ·摩尔 ? 1 并且 58.84kJ ·摩尔 ? 1 分别地。

Kinetics of Non-catalyzed Decomposition of Glucose in High-temperature Liquid Water

葡萄糖的分解动力学从 180 ～ 220  ? 在高温度的液体水(HTLW ) 里被学习 ? 跴? 跴?

Reactions between Ti and Ti_3SiC_2 in temperature range of 1 273-1573K

The reactions of Ti3SiC2 and Ti in the temperature range of 1 273?1 573 K under a pressure of 20 MPa were investigated.The results confirm that Ti reacts with Ti3SiC2 above 1 273 K and new phases like TiCx,Ti5Si3 and TiSi2 are identified.The reactions are closely related to temperature and content of Ti3SiC2 in Ti.During the reaction process,Ti3SiC2 decomposes in two different modes.The first is caused by the de-intercalation of Si from it and the TiCx is formed by the remained titanium and carbon;the second is that the carbon is separated from the Ti3SiC2 and reacts with titanium furthermore.The diffusing of silicon is believed to be the determinant ingredient of the reaction.

Fabrication and characterization of SmO_(0.7)F_(0.2)FeAs bulk with a transition temperature of 56.5 K

The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction （XRD） results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a（1-a/（3b））]. The upper critical fields, H c2 ≈ 256 T （T = 0 K）, was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application.

Realizing Complete Solid-Solution Reaction to Achieve Temperature Independent LiFePO_(4) for High Rate and Low Temperature Li-Ion Batteries

The lithium iron phosphate battery(LiFePO4 or LFP)does not satisfactorily deliver the necessary high rates and low temperatures due to its low Li+diffusivity,which greatly limits its applications.The solid-solution reaction,compared with the traditional two-phase transition,needs less energy,and the lithium ion diffusivity is also higher,which makes breaking the barrier of LFP possible.However,the solid-solution reaction in LFP can only occur at high rates due to the lattice stress caused by the bulk elastic modulus.Herein,pomegranate-like LFP@C nanoclusters with ultrafine LFP@C subunits(8 nm)(PNCsLFP)were synthesized.Using in situ X-ray diffraction,we confirmed that PNCsLFP can achieve complete solid-solution reaction at the relatively low rate of 0.1C which breaks the limitation of low lithium ion diffusivity of the traditional LFP and frees the lithium ion diffusivity from temperature constraints,leading to almost the same lithium ion diffusivities at room temperature,0,−20,and−40℃.The complete solid-solution reaction at all rates breaks the shackles of limited lithium ion diffusivity on LFP and offers a promising solution for next-generation lithium ion batteries with high rate and low temperature applications.

An efficient light-to-heat conversion coupling photothermal effect and exothermic chemical reaction in Au NRs/V_(2)C MXene membranes for high-performance laser ignition

MXene,a new type of two-dimensional materials,have been demonstrated as one of the best photothermal materials owing to their strong light-matter interaction and high photothermal conversion efficiency in recent years.Herein,we report the intriguing light-to-heat conversion property of vanadium carbide(V_(2)C)MXene under irradiation of millisecond laser pulse.Unlike the typical photothermal materials,the V_(2)C MXene not only converts the incident laser energy to heat by the physical photothermal effect,but also triggers the exothermic oxidation of the V_(2)C MXene.The oxidation could be greatly promoted with addition of plasmonic Au nanorods(Au NRs)for light absorption enhancement.Owing to the unique light-to-heat conversion property,the Au NRs/V_(2)C MXene membrane could serve as high temperature pulse(HTP)generators that is proposed for numerous applications with high demand for immediacy.As a proof-of concept application,Au NRs/V_(2)C MXene membrane was applied for laser ignition of the high energy density materials,such as 2,4,6,8,10,12-(hexanitrohexaaza)cyclododecane(HNIW or CL-20).An improved ignition performance,in terms of lowered laser threshold,is achieved as compared to the state-of-the-art light-to-heat conversion materials.

In Situ High-Temperature Reaction-Induced Local Structural Dynamic Evolution of Single-Atom Pt on Oxide Support

The dynamic evolution of active site coordination structure during a high-temperature reaction is critically significant but often difficult for the research of efficient single-atom catalysts(SACs).Herein,we for the first time report the in situ activation behaviors of the local coordination structure of Pt single atoms(Pt_(1))during the high-temperature oxidation of light alkanes.The distinctly enhanced activity of the catalyst is attributed to the in situ evolved Pt_(1)−oxygen vacancy(Pt_(1)−OV)combination ensemble as an efficient and stable active site.Theoretical calculations reveal that the lattice oxygen adjacent to Pt_(1)and the H dissociated from CH4 constitute the lattice hydroxyl,which is the initial step in the formation of the Pt_(1)−OV combination.Pt_(1)and nearby unsaturated Mn can donate the charge back to O−O to promote the dissociation of O_(2).This work provides molecular-level insight into the in situ reaction-induced evolution of a single-atom coordination environment for designing efficient SACs under harsh conditions.

Modified room temperature solid-state synthesis of yttria-stabilized zirconia(YSZ) nano-powders for solid oxide fuel cells

High-performance solid oxide fuel cell(SOFC) is in urgent need of high-quality electrolyte powders with high reactivity and chemical uniformity.Here,8 mol% Y_(2)O_(3) doped ZrO_(2)(YSZ) nano-powders were synthesized by an improved solid-state reaction method at ambient temperature,and were applied to the fabrication of SOFC electrolytes.YSZ nano-powders show average grain sizes of ^(2)0 nm and high dispersibility,which is comparable with or even better than some other chemical methods.Benefitting from their high reactivity,dense YSZ electrolytes(relative density of 97.9%) can be obtained at a relatively low sintering temperature of 1400℃.The optimized electrical conductivity reaches up to a high value of0.034 S/cm at 800 0C in air.The anode supported single cell with the construction of Ni-YSZ/YSZ/Sm_(0.2)Ce_(0.8)O_(2-δ)(SDC)/La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF) exhibits the peak power density of 0.827 W/cm^(2) at800℃ while taking wet H_(2) as fuels and ambient air as oxidants.

高温改性钢渣活化过硫酸盐降解甲基橙和苯酚的反应机制

采用高温改性钢渣活化过硫酸盐(peroxymonosulfate,PMS)降解甲基橙(methyl orange,MO)和苯酚(phenol,AR)。考察了改性钢渣投加量、PMS浓度、初始pH值、反应温度对MO和AR降解效果的影响。在改性钢渣质量浓度为9.0 g/L、PMS物质的量浓度为12.0 mmol/L、初始pH值为7.0、反应温度为25℃的条件下,反应90 min,30 mg/L MO和15 mg/L AR的降解率分别达到90.5%和100%。材料表征分析结果表明,高温改性钢渣比表面积增大、孔隙率高、催化氧化PMS性能好,且重复利用仍有较好的原位恢复性能。自由基淬灭和电子顺磁共振波谱实验说明,高温改性钢渣/PMS反应体系存在非自由基(1 O 2)和自由基(SO_(4)^(-)·和·OH),发挥了碱活化PMS和铁氧化物活化PMS的共同作用,最终将MO和AR降解为小分子物质。

基于亚磷酸自催化的含磷季戊四醇酯润滑油的合成和性能

以季戊四醇与亚磷酸、脂肪酸为原料,采用两步法合成工艺制备了含磷季戊四醇酯,利用FTIR、NMR及元素分析对其结构进行表征,并对其高温稳定性进行评价。实验结果表明,第一步酯化反应在170~185℃下,无催化剂的体系反应效果与硫酸催化反应体系接近且优于氧化亚锡体系,说明亚磷酸在反应体系中既作底物,同时又起到了催化作用;第二步酯化反应在220~230℃下,无催化剂的亚磷酸体系与表现最佳催化效果的氧化亚锡体系的反应效果相当,进一步说明亚磷酸具有良好的自催化能力。与未进行亚磷酸改性的季戊四醇酯(典型的MIL-PRF-23699规范基础油)相比,含磷季戊四醇酯润滑油的分解温度提升约76℃,HPDSC氧化温度提升约25℃,表明亚磷酸改性可很好地提升季戊四醇酯润滑油的高温性能,使其在高温领域的应用得到拓展。

NaYSiO_(4)∶Ce^(3+)蓝色荧光粉的发光性质及其在白光发光二极管上的应用

采用高温固相法合成了NaYSiO_(4)∶xCe^(3+)(0.01≤x≤0.05)系列蓝色荧光粉。NaYSiO_(4)∶xCe^(3+)荧光粉在250~360 nm之间的宽带吸收能与紫外LED芯片很好地匹配。NaYSiO_(4)∶xCe^(3+)荧光粉中存在多个Ce^(3+)离子荧光中心,且在紫外光激发下表现出峰值波长位于414 nm附近的宽带蓝光发射。NaYSiO_(4)∶0.02Ce^(3+)荧光粉在300~350 nm紫外光激发下量子效率在25%以上。NaYSiO_(4)∶0.02Ce^(3+)荧光粉表现出优良的化学稳定性,在水中浸泡14 d后荧光强度和量子效率几乎不变。将NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉、商用(Sr,Ba)_2SiO_(4)∶Eu^(2+)绿色荧光粉和商用(Ca,Sr)AlSiN_(3)∶Eu^(2+)红色荧光粉涂覆于310 nm紫外LED芯片上制备得到了显色指数高达95的LED器件。当驱动电流从50 mA逐渐增大到300 mA时,制备的LED器件表现出稳定的暖白光发射,其色坐标几乎不变。上述结果说明,本研究报道的NaYSiO_(4)∶0.02Ce^(3+)蓝色荧光粉在紫外LED芯片驱动的白光发光二极管照明上有着潜在应用价值。

马来酸酐改性高掺量橡胶沥青制备与性能

使用高度降解的再生橡胶(DR)制备了高掺量橡胶沥青(HCRA),通过衰减全反射傅里叶变换红外光谱仪、凝胶渗透色谱仪、动态剪切流变仪和动态力学分析仪,对比研究了马来酸酐(MAH)预接枝DR改性与MAH和DR直接共混改性对HCRA结构与性能的影响,探讨了两种改性方法的改性机理。结果表明,MAH预接枝DR时发生了由烯烃双键和烯丙基碳氢原子提供活性位点的自由基取代反应,而MAH和DR与沥青直接共混时,存在自由基取代反应和酯化反应两种反应,并以后者为主;MAH改性HCRA的溶胶组分中以中低分子量组分为主;MAH改性显著改善了HCRA的高、低温流变性能。此外,两种改性方法对HCRA的结构与性能均有影响,且随MAH掺量的变化存在明显差异。

基于TDLAS的H_(2)S高温反应特性实验研究

电站锅炉在低NO_(x)燃烧过程中因锅炉内还原性气氛浓度较高,会产生较多H_(2)S气体。针对H_(2)S因具有易燃、强腐蚀性、剧毒性而可能对火电厂造成多种危害的问题,采用可调谐二极管激光吸收光谱(tunable diode laser absorption spectroscopy,TDLAS)方法结合多通池和计算机搭建低气体摩尔分数在线测量系统,实现了对混合气体中摩尔分数在10–6量级H_(2)S的精确在线测量,并利用该测量系统进行了H_(2)S高温反应实验,探究实验温度和混合气体中O_(2)摩尔分数对该反应的影响。实验结果展示了压力为80 kPa、O_(2)摩尔分数为0~5%的条件下,H_(2)S开始发生化学反应的温度随O_(2)摩尔分数变化的变化规律,整体而言,混合气体中O_(2)摩尔分数越高,H_(2)S开始发生化学反应的温度越低。实验结果可以为锅炉烟气中H_(2)S的生成、转化和危害控制提供一定数据基础。