Some New Results from the Electron Theory on the Elastical of Alkahoe Earth Metals and Rare Earth Elements

With the introduction of Poisson's ratio in the expression of Young's modulus,nearly all the theoretical values of the various elastic moduli for the alkaline earth metals and rare earth elements can be greatly refined, with the single exception of the theoreticalvalue of Young's modulus for Pr which is slightly increased This points to the validityof the new theory, that the bulk modulus is independent of the Poisson's ratio, and further that the valency electron structures of solids as determined by Yu's theory are correct.

Electron Donating Property and Catalytic Activity ofPerovskite-type Mixed Oxides (ABO_3) Consisting of Rare Earth and 3d Transition Metals

The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides

Research on K-V-rare Earth Metal Catalysts for Diesel Soot Oxidation

Five types of KNO_3-NH_4VO_3-rare earth metal nitrate（K-V-rare earth metal） catalysts supported on a-porous alumina ceramic substrates were prepared by a coating method. All the catalysts were characterized by X-ray diffraction and thermogravimetry/differential scanning calorimetry. Catalytic activities were evaluated by a soot oxidation reaction using a temperature-programmed reaction system. The experimental results show that the addition of rare earth metal compound could obviously improve the catalytic activities of the K-V-based catalysts. The proper ratio of K-V-rare earth metal catalysts can not only lower the soot onset ignition temperature, but also quicken the soot oxidation rate. The crystalline phases formed by K, V, and rare earth metal are stable.

Syntheses of Alkaline Earth and Lanthanide Cryptates with Pyridine-Based Group

New alkaline earth metal cryptates [ML]（NO3）2 ·2H2O （M=Ca^2＋, Sr^2＋, Ba^2＋; L = 1, 4,12,15,18, 26, 31, 39, 42, 43, 44-undecaazapentacyclo- [ 13.13.13.1^6,10 .1^20,24 .1^33,37 ]-tetratetraconta -4, 6, 8, 10（44）, 11, 18, 20, 22, 24（43）, 25, 31, 33, 35, 37（42）, 38-pentadecaene） were synthesized by [2 ＋ 3 ] template condensation of tris（2-aminoethyl） amine with 2, 6-diformylpyridine, and then by transmetallation reactions of the calcium cryptate [CaL] （NO3）2·2H2O with corresponding lanthanide ions; three lanthanide cryptates [ LnL] （NO）3·3H2O （Ln = Eu, Gd, Tb） were synthesized and characterized by physical methods. The crystal structure of the terbium cryptate [TbL] （NO）3·3H2O was studied by X-ray analysis. The central atom was coordinated by three pyridyl and six imino nitrogen atoms and exhibited a distorted tricapped trigonal prismatic coordination geometry.

An alkaline fusion mechanism for aluminate rare earth phosphor:cation-oxoanion synergies theory

Waste aluminate rare earth phosphor is an important rare earth elements (REEs) secondary resource, which mainly consists of BaMgAl1()O|7:Eu2+(BAM) and CeMgAl11O19:Tb^3+(CMAT). Alkaline fusion process is widely used to recycle REEs from aluminate phosphor, but the related theory remains imperfect. In this paper, a series of alkaline fusion experiments of CMAT were performed to describe the phase change law of CMAT reactions. Based on comprehensive analysis, cation-oxoanion synergies theory (COST) was proposed to explain the aluminate phosphor structure damage. On the mirror plane of aluminate phosphor crystal structure, alkali metal cations (Na^+,K^+) would substitute rare earth ions, while free oxoanion (OH^-, CO3^2-, O2^2-) can combine with rare earth ions. These two ionic forces ensure that rare earth ions can be substituted by cations. Then, the structure is decomposed. Morphological analysis shows that observable expression of COST can be described by shrinking core model after simplification. Reaction rate constant calculated indicates that the reaction degree is nanometers per second. COST provides a more complete mechanism, and it can help improve rare earth recycling technology furtherly.

Study on sulfur migration in activated carbon adsorption-desorption cycle: Effect of alkali/alkaline earth metals

Activated carbon(AC)has been widely used in the removal of SO_(2) from flue gas owing to its well-developed pore structure and abundant functional groups.Herein,the effect of alkali/alkaline earth metals on sulfur migration was investigated based on the dynamic adsorption and temperature programmed desorption experiment.The adsorption and desorption properties of six types of AC(three commercial and three laboratory-made)were carried out on a fixed-bed experimental device,and the physical and chemical properties of samples were determined by X-ray fluorescence,X-ray diffraction,scanning electron microscopy/energy dispersive X-ray,and X-ray photoelectron spectroscopy analysis.The experimental results showed that the adsorbed SO_(2) cannot be completely desorbed by increasing the regeneration temperature(350-850℃),while the SO_(2) fixed in the AC combines with the Ca-based minerals in the ash to form a stable sulfate.For different samples,higher ash content,higher CaO content in the ash and a more developed pore structure lead to a higher SO_(2) fixation rate.Moreover,the multiple adsorption-desorption cycles experiment showed that the effect of SO_(2) fixation is mainly reflected in the first cycle,after which the adsorption and desorption amount are approximately the same.This study elucidates the effect of alkali/alkaline earth metals on the adsorption-desorption cycle of AC,which provides a deeper understanding of sulfur migration in the AC flue gas desulfurization process.

Influence of preparation method on performance of a metal supported perovskite catalyst for combustion of methane

A different method was employed for the preparation of a metal supported perovskite catalyst for the catalytic combustion of methane.The prepared metallic catalysts were characterized by means of X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and also by ultrasonic and thermal shock tests and catalytic activity.It was found that the process factors during the preparation,e.g.the preparation of the catalyst precursor and the coating slurry,the calcination te...

Addition of cerium and yttrium to ferritic steel weld metal to improve hydrogen trapping efficiency

The applicability of Ce and Y as promising candidate elements to form irreversible traps in weld metal was investigated by thermal desorption spectroscopy(TDS) with gas chromatography(GC). The precise nature of the precipitate particles newly formed in the weld metal by the addition of Ce and Y to a certain alloy system was characterized. Moreover,the hydrogen trapping efficiency expressed as the reduction of the diffusible hydrogen in the weld metal was analyzed. The results showed that the addition of Ce and/or Y to this alloy system led to the formation of a mixed type of(Ce,Ti)-based oxide,(Y,Ni)-based carbide,or(Ce,Y,Ti)-based oxide particles. Because of the high activation energy of the mixed type of particles(≥ 150 k J/mol),the trapping efficiency for hydrogen was considered to be sufficiently high to effectively reduce the diffusible hydrogen content.

Roles of crystal defects in the persistent luminescence of Eu^(2+), Dy^(3+) co-doped strontium aluminate based phosphors

The roles of different point defects in persistent luminescence of SrAl2O4：Eu,Dy phosphors were investigated. The research results showed that Dyer plays an important role in the persistent luminescence of SrA1EO4：Eu, Dy phosphors. It can serve as the electron trap of suitable depth for persistent luminescence. V~ does not serve as the electron trap of suitable depth, but its existence can increase the depth of electron traps. There is interaction between the Dy^3＋（ DySr ） and the Eu^2＋（Eu^x Sr ）, and only if the distance between the Dy^3＋（DySr） and the Eu^2＋ （Eu^x Sr） is close enough, the Dyer can work as an effective electron trap. The point defect of V＂ Sr can be hole trap, but the change of its density in crystal matrix does not arouse the obvious change of persistent luminescence.

Applications of Rare Earth Promoted Transition Metal Sulfides in Electrocatalysis

With the rapid consumption of fossil fuels and the resulting environmental problems,researchers are working to find sustainable alternative energy and energy storage and conversion methods.Transition metal sulfur compounds have attracted extensive attention due to their excellent electrical conductivity,low cost,adjustable components and good electrocatalytic performance.As an alternative to noble metal catalysts,they have emerged as a promising electrocatalyst.However,their low catalytic activity and poor stability limit their large-scale practical applications.Rare earth elements,known as industrial vitamins,are widely used in various fields due to their special redox properties,oxygen affinity and electronic structure.Therefore,the construction of rare earth promoted transition metal sulfides is of far-reaching significance for the development of catalysts.Here,we review the applications of various rare earth promoted transition metal sulfides in energy storage and conversion in recent years,which focuses on three ways in rare earth promoted transition metal sulfide,including doping,interfacial modification engineering and structural facilitation.As well,these materials are used in electrochemical reactions such as OER,HER,ORR,CO_(2)RR,and so on,in order to explore the important role of rare earth in the field of electrocatalysis,the future challenges and opportunities.

东昆仑大格勒地区稀有和稀土矿化碱性杂岩体的发现及意义

稀有、稀土元素由于其特殊的属性对国民经济、国家安全和科技发展具有重要的战略意义。与碱性岩类相关的稀有、稀土矿产资源储量十分丰富,近年来对其勘探和开发越来越受到重视。青海省地质调查院在东昆仑中段大格勒地区首次发现了稀有和稀土矿化碱性杂岩体,岩石类型主要为含尖晶石磷灰石蛇纹石化橄榄岩、含磷灰石金云母霞石单斜辉石岩、橄榄辉长岩、含磷灰石金云母角闪石岩、磁铁矿化含橄榄石磷灰石碳酸岩等,其中含矿岩石为碳酸岩、橄榄岩、辉石岩等。矿石矿物主要为烧绿石、铌钽铁矿、磷灰石、独居石、钛铁矿。现初步圈定Nb、P矿体一条,矿体厚3.8~56.56 m,Nb_(2)O_(5)品位最高6.9%,平均0.71%;P_(2)O_(5)品位最高14.5%,平均品位5.6%,Ta和REE也伴有矿化,显示了很好的含矿性。这一发现大大拓展了青藏高原稀有、稀土矿的找矿空间,为发现新的、优质的稀有稀土矿产提供重要启示,具有重要的找矿和战略意义。

碱性花岗岩型稀有稀土矿床类型及成矿作用研究进展

碱性花岗岩因富集稀有稀土元素而成为一种重要的成矿岩体。近年来碱性花岗岩型稀有稀土矿床在矿床类型分类、成矿流体和成矿物质来源及成矿机制等方面取得一些重要的研究进展。碱性花岗岩通常富集高场强元素(HFSEs)和稀土元素(REEs),根据暗色矿物与主矿种之间的关系该类型矿床可分为富Nb-Zr-REEs钠(铁)闪石碱性花岗岩型、富Nb-U-HREEs碱性杂岩型和富Nb-Sn黑云母碱性花岗岩型3种类型。碱性花岗岩型稀有稀土矿床成矿时代主要集中于古生代-新生代,与大陆、超大陆的裂解和聚合后期伸展构造背景有关。成矿流体经历了早期岩浆分异与晚期热液交代2个演化阶段。研究表明从岩浆中出溶的成矿流体具有低温、高盐度、富F等特征,可导致HFSEs和REEs等元素在碱性花岗岩中超常富集。母岩浆中不相容元素浓集到出溶流体中,并随着后期含F流体结晶或交代原岩而形成稀有稀土矿物。成矿物质通常来源于地幔岩浆或地幔与地壳的混合,但也可能来源于俯冲洋壳。岩浆结晶分异与热液交代为碱性花岗岩型稀有稀土矿床的2种主要成矿机制,但该类矿床大多为2种机制的复合形成。

低生焦活性缓释重油裂化催化剂开发及工业应用

采用碱土金属复合改性和固相稀土技术开发了低生焦活性缓释重油裂化催化剂M,在R石化公司重油催化裂化装置进行了工业应用。应用结果表明,在催化原料和操作工况大致相当的情况下,与空白标定相比,新催化剂M占系统藏量达到50%时,液收增加1.64个百分点,油浆收率和焦炭收率分别下降0.44和1.30个百分点,汽油收率增加0.62个百分点,柴油收率增加1.58个百分点,表明该催化剂重油转化能力强,生焦低。

硫醚与2-甲基-1,5-己二烯反应的机理研究

采用密度泛函理论对硫醚与2-甲基-1,5-己二烯的反应机理进行了详细的理论探究.计算结果表明,该反应历程主要包含活性物种的生成、2-甲基-1,5-己二烯的插入、另一分子的硫醚的碳氢键活化三部分.在2-甲基-1,5-己二烯插入步骤中,发现其采用6-5-re-插入时需要克服的活化能垒最低,反应时更为占优,在进行烯烃分子内碳碳双键插入完成闭环反应时相对比较容易.通过能量对比探明硫醚的C-H键活化需要克服的能垒最高,为该反应的速控步.

高效长余辉发光薄膜及粉体的溶胶-凝胶工艺研究

研究了溶胶 凝胶工艺制备SrAl2 O4 ∶Eu2 + ,Dy3+ 高效长余辉发光薄膜及粉体的工艺条件 ,以无机盐为原料 ,成功制备了均一、稳定、透明的SrAl2 O4 溶胶 ,并在较低温度下制备了均匀、无裂纹的发光薄膜和颗粒均匀的针状纳米发光粉体。通过热失重和X射线衍射结果分析了样品的结晶过程和晶相组成 ,并通过扫描电镜、透射电镜和荧光光谱的分析对薄膜和粉体的微结构、表面形态及发光性能进行了表征。结果表明 ,在本文的工艺条件下 ,制备的薄膜和粉体的发光特性与传统的高温固相烧结法相似 ,但烧结温度可降低 3 0 0℃左右。

溶胶凝胶法制备TiO_2纳米颗粒及其光催化性能

考察了通过溶胶凝胶法进行过渡金属(Fe3+、Zn2+、Co2+、Ni2+、Cr3+和Sn4+)和稀土元素(La3+、Pr3+、Nd3+、Ce4+、Sm3+、Tb3+、Eu3+、Gd3+、Y3+和Dy3+)掺杂的TiO2纳米颗粒的光催化活性,以及通过超声波处理反应过程中的溶胶所制备得到的TiO2纳米颗粒的光催化活性。结果表明0.5%Sn4+、0.5%La3+、0.5%Y3+和0.5%Eu3+(质量分数)掺杂的TiO2纳米颗粒在降解甲基橙溶液的反应中,其光催化活性提高2%～7%;其它的掺杂则使TiO2纳米颗粒的光催化活性降低0.5%～25%;在TiO2纳米颗粒的制备过程中,对溶胶进行超声辐照可使其光催化活性提高15%以上,这是提高TiO2纳米颗粒光催化活性的一条新途径。

碱土金属铝酸盐系列长余辉磷光体的制备研究

研究了MAl2O4∶Eu2+(M=Ca,Sr,Ba)磷光体的制备过程,通过向磷光体中引入微量Dy3+,B3+等添加剂离子,得到了发绿色光的超长余辉磷光体,余辉发光初始亮度达4.8cd·m-2,激发停止50h后,其余辉发光仍清晰可见。制备出发紫色光、蓝色光及黄色光的碱土金属铝酸盐系列长余辉磷光体。分析了各磷光体发射光谱、激发光谱及余辉发光,讨论了磷光体的光谱移动以及Eu2+在碱土金属铝酸盐中的发光。

稀土基汽车尾气催化剂的研究Ⅰ:催化剂老化和SO_2添加对催化活性的影响

制备了低Pt、Rh担载量的稀土基催化剂体系 ,研究了贵金属担载量、催化剂高温老化、抗硫水热老化和SO2 对催化活性的影响。结果表明 :随着贵金属质量分数从 0 2 5 %降低到0 1% ,CO、碳氢化合物 (HC)和NO的起燃温度分别平均提高 2 0℃ ;随着m(Pt)∶m(Rh)从 5∶1提高到 9∶1,CO、HC和NO的起燃温度分别提高 17、2 0和 5 3℃ ;当在反应体系中添加SO2 ,随SO2 体积分数从 0 0 0 2 %增加到 0 0 1% ,CO和NO的起燃温度和完全转化温度分别平均提高2 0℃ ,而对于HC ,催化活性几乎保持不变 ;催化剂在水热含硫条件下连续老化 4 0 0h ,CO、NO和HC的起燃温度分别为 2 5 2、2 6 7和 30 3℃ ,仍具有良好的反应活性。表明该稀土基催化剂在一定条件下 。

镧、铈在贵金属型汽车尾气净化催化剂中的作用

考察了镧、铈 锆对γ Al2 O3 载体热稳定性以及对汽车尾气净化催化剂Pt Rh/γ Al2 O3活性的影响。试验结果表明 ,在γ Al2 O3 中加入质量分数为 5 %的La2 O3 和 12 .5 %的CeO2 ZrO2制备的稀土复合氧化铝载体具有较高的比表面积和较大的孔体积 ;该载体负载Pt、Rh贵金属后得到的贵金属型三效催化剂Pt Rh/γ Al2 O3 (RN 1)在 92 0℃、10 %水蒸气气氛中老化 2h后仍具有较低的起燃温度、较宽的空燃比窗口和较高的转化率。

碱及碱土金属对准东煤热解特性及动力学影响分析

利用程序升温热重(TG)技术对准东原煤(R-form)和酸洗煤(H-form)样品的热解过程进行了研究,同时,采用分布活化能模型(DAEM)法对两者的热解动力学参数进行了计算。结果表明,准东煤在热解过程中保持了丰富的孔隙结构;碱及碱土金属(AAEM)的存在不会对准东煤大分子网络结构造成显著影响,但会提高准东煤的平衡水分含量及二次脱气阶段挥发分释放速率,降低其主热解阶段挥发分释放速率及热解最终失重率;DAEM法可以在较宽的温度范围内对准东煤的热解过程进行准确的描述,R-form和H-form煤样品的热解活化能均随转化率的增大而升高;相同转化率下R-form煤样品的活化能高于H-form,前者活化能分布函数的最大值出现在261.85kJ/mol处,而后者出现在264.51kJ/mol处;AAEM的存在使准东煤的热解活化能升高且分布更加集中,使其热解反应活性降低;准东煤热解的频率因子与活化能之间呈现明显的动力学补偿效应。