Cu负载Fe柱撑钠化海泡石: 结构特点及其丙烯选择性催化还原NO性质研究

采用羟基铁离子柱撑钠化海泡石改性后, 以浸渍法制备了铜负载铁柱撑钠化海泡石Cu/Fe-NaPILCS催化剂, 作为比较以浸渍法制备了铁负载钠化海泡石(Fe-NaSep), 铜负载钠化海泡石(Cu-NaSep)和铜铁负载钠化海泡石(Cu/Fe-NaSep)催化剂. 并将它们应用于C₃H₆选择性催化还原NO的反应(C₃H₆-SCR). 通过X射线衍射仪(XRD)、TGA-DTG分析、N₂-等温吸附/脱附、H₂-程序升温还原(TPR)和X射线光电子能谱仪(XPS)等技术对样品进行表征. N₂-等温吸附/脱附和TGA-DTG分析结果表明, Fe-NaPILCS的比表面积和孔体积较海泡石原矿具有较大的增加, 热稳定性也明显提高|XRD和XPS结果表明, 在Cu/Fe-NaPILCS催化剂上同时存在Fe^3＋/Fe^2＋和Cu^2＋/Cu^＋不同氧化态的氧化物种, 在Cu和Fe之间存在电子迁移. H₂-TPR结果表明, Cu/Fe-NaPILCS催化剂上存在大量的孤立铜离子物种(isolated Cu^2＋-ions, (Cu^2＋)_i). Fe柱撑钠化海泡石负载的Cu/Fe-NaPILCS催化剂的催化活性明显优于未柱撑海泡石负载的Cu/Fe-NaSep催化剂, 这可能与Cu/Fe-NaPILCS具有较大的比表面积、孔体积和更优的氧化还原性能, 及其具有更多有利于C₃H₆-SCR反应的(Cu^2＋)_i物种有关.     

镝掺杂铁氧体纳米晶的制备、表征和磁性

采用化学共沉淀法制备出了镝掺杂铁氧体纳米晶, 利用透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅立叶红外光谱仪(FTIR)、古埃磁天平、振动样品磁强计(VSM)、X射线能谱仪(EDX)等仪器对产物进行了表征, 研究了Dy^3＋掺杂量对铁氧体纳米晶的结构、磁性和粒度的影响. 结果表明: 适量稀土元素镝离子的掺杂可以提高尖晶石型铁氧体的磁性、降低矫顽力, 当n(Fe^3＋)∶n(Dy^3＋)＝14∶1时其磁性最强. Dy^3＋替代或充填进入了尖晶石晶格, 且主要占据B位. 掺杂了镝的铁氧体磁性纳米粒子粒度变小, 且分布更集中、均匀, 当Dy^3＋加入量为n(Fe^3＋)∶n(Dy^3＋)＝14∶1时铁氧体纳米粒子的平均粒径由掺杂前的14 nm降低到到8 nm. 这种具有超顺磁性的软磁铁氧体纳米晶可应用于纳米磁液领域.     

羧甲基纤维素/Fe3O4复合纳米磁性材料的制备、表征及吸附性能的研究

采用改进的氧化沉淀法在羧甲基纤维素(CMC)体系中制备了以磁性纳米Fe₃O₄为核心, 外层包覆羧甲基纤维素的复合磁性纳米材料. 用透射电镜、X射线衍射、红外光谱、Zeta电位和震动样品磁强计对复合纳米Fe₃O₄进行了表面形貌、结构和磁学的表征. 在此基础上研究了复合纳米Fe₃O₄对Cu^2＋的吸附性能, 探讨了溶液pH、反应时间和 Cu^2＋的初始浓度对其吸附性能的影响. 实验结果表明, 复合Fe₃O₄粒子为反尖晶石型, 平均粒径在40 nm左右, 羧甲基纤维素在Fe₃O₄粒子表面是化学吸附, 复合Fe₃O₄粒子的饱和磁化强度为36.74 emu/g, 在中性溶液中Cu^2＋的吸附量最高, 吸附平衡时间为1.5 h, 二级动力学模型能够很好地拟合吸附动力学数据, 吸附等温数据符合Langmuir模型. 复合纳米Fe₃O₄对Cu^2＋的吸附机理主要为表面配位反应.     

X-射线吸收谱原位表征Cu-Zn/SiO2催化剂Cu价态

铜基催化剂的价态组成与制备方法、还原温度有关,也是决定其催化性能的关键因素.本文对比研究Cu-Zn/SiO₂和Cu/SiO₂催化剂前驱体在不同还原温度下的价态组成及其醋酸甲酯加氢性能.采用同步辐射X射线吸收谱原位表征催化剂前驱体的Cu K边的X射线近边吸收谱（XANES）,通过线性组合分析方法（LCF）拟合XANES吸收谱得到了催化剂前驱体在不同还原温度下氧化态（Cu²⁺、Cu⁺）和金属态（Cu⁰）的组分含量.结果表明：（1）采用蒸氨法添加Zn制备的Cu-Zn/SiO₂催化剂前驱体铜组分还原度高;（2）催化剂前驱体在还原过程中Cu⁺主要存在于低温还原阶段（<250℃）,且Cu⁰+Cu⁺含量较低（≤ 40%）;（3）金属态铜是醋酸酯加氢反应的活性中心.     

Cu0/Cu2+修饰Ti3C2Tx二维材料用于电催化还原二氧化碳

以Ti₃AlC₂和CuCl₂·2H₂O为前驱体,成功制备了Cu⁰纳米颗粒修饰和Cu²⁺自插层的手风琴状二维催化剂Cu⁰/Cu²⁺-Ti₃C₂T_x,用于电催化还原CO₂。对材料的电化学性能进行了测试,结果表明,在CO₂饱和的0.5 mol/L KHCO₃电解液中,与原始的Ti₃AlC₂相比,Cu²⁺/Cu⁰-Ti3C2Tx催化剂电催化CO₂转化为乙烯(C₂H₄)的起始电位从-0.65 V(vsRHE)降至-0.01 V(vs RHE),最大电流密度从0.19 mA/cm²增至2.50 mA/cm²     

助剂含量对CuLi/AC 催化剂结构及甲醇氧化羰基化反应性能的影响

采用微波辐射法制备出不同助剂含量的CuLi/AC(活性炭)催化剂, 考察了其在甲醇气相氧化羰基化合成碳酸二甲酯(DMC)反应中的催化性能, 使用X射线衍射、 扫描电子显微镜、 比表面积、 H₂程序升温还原、 X射线光电子能谱和CO程序升温脱附对催化剂的结构进行了表征. 研究结果表明, 添加适量的Li有助于铜物种还原为低价态的Cu⁰, 形成颗粒尺寸更小、 分布更加均匀的铜纳米颗粒, 并高度分散在活性炭载体表面. 催化剂活性与表面单质铜的含量有关, 即Cu⁰是催化剂的主要活性物种, 并且Cu⁰的晶粒尺寸越小, 催化剂活性越好. 添加Li后增加了催化剂表面的CO弱吸附位, 有利于CO对Cu-OCH₃的插入反应, 因此提高了催化活性. 随着Li含量的增加, DMC的时空收率逐渐升高, 当Li添加质量分数达到0.15%时, DMC的时空收率达到最高值540.6 mg·g^-1·h^-1, 甲醇转化率为4.5%, DMC选择性为81.4%.     

5,5-二甲基乙内酰脲在化学镀铜中的作用

在以酒石酸钾钠和乙二胺四乙酸二钠为双配位剂、 甲醛为还原剂的化学镀铜液中, 研究了5,5-二甲基乙内酰脲(DMH)在化学镀铜中的作用. 化学镀铜实验结果表明, DMH提高了镀液的稳定性; 扫描电子显微镜(SEM)结果表明, DMH使镀层颗粒尺寸减小, 镀层光亮致密; 紫外-可见光谱结果表明, DMH在镀液中与Cu(II)不发生强配位作用; 线性伏安扫描结果表明, DMH在化学镀铜过程中能抑制Cu⁺的产生或促进Cu⁺快速还原, 降低甲醛的氧化速率; X射线衍射(XRD)结果表明, 在含和不含DMH化学镀铜液中, 得到的铜镀层均呈现面心立方混晶结构的特征, 且未出现Cu₂O夹杂衍射峰.     

反应过程中Cu物种演变对其催化甲醇氧化羰基化反应活性的影响

以NH₄Y分子筛为载体、 乙酰丙酮铜为铜源, 采用固相反应法制备了无氯CuY催化剂, 并用于催化甲醇氧化羰基化合成碳酸二甲酯(DMC). 结合不同反应时间催化剂的X射线衍射(XRD)、 N₂吸附-脱附、 热重(TG)、 程序升温脱附/还原(NH₃-TPD/H₂-TPR)、 透射电子显微镜(TEM)和X射线光电子能谱(XPS)等表征结果, 分析了反应过程中Cu物种演变对其催化活性的影响. 结果表明, 新鲜催化剂中铜物种主要以Cu⁺形式存在, 占铜物种的48%; 随着反应的进行, 活性中心Cu⁺逐渐被氧化为Cu²⁺, 进而生成CuO物种, 部分CuO逐渐迁移至催化剂外表面. 在反应100 h内, Cu⁺含量逐渐减小至36.7%, CuO含量增加, 导致DMC的时空收率及选择性不断下降, 副产物二甲氧基甲烷(DMM)和甲酸甲酯(MF)的选择性逐渐提高. 当反应时间延长至190 h时, Cu⁺含量为33.6%, 略有下降, DMC的时空收率和选择性趋于平稳. 继续延长反应时间至300 h, 催化剂中铜物种状态基本不变, 催化剂催化性能保持稳定.     

铈改性的铜/六方介孔二氧化硅催化剂在温和反应条件下高效地将草酸二甲酯氢化为乙二醇（英文）

采用蒸氨法制备了一种高效的铈改性铜/六方介孔二氧化硅(xCe-Cu/HMS)催化剂，用于草酸二甲酯(DMO)气相化学选择性氢化成乙二醇(EG)。铈助剂可以显著提高催化剂的性能，在引入1.2%的铈后，催化剂的性能最好。在温和的条件下(200℃，2.0MPa, H₂/DMO=100, LHSVDMO=1.2h^-1), DMO转化率和EG选择性分别达到了99.6%和96.3%。表征结果显示，Ce修饰的Cu/HMS可以增强Cu与载体之间的相互作用，改善Cu的分散性，并保持适当的Cu⁺/(Cu⁺+Cu⁰)的比例。本研究采用简单、低成本的路线，合成了具有优良催化性能的Ce改性的Cu-HMS催化剂，实现了在温和的条件下DMO向EG的高选择性转化。     

探究二氧化硫在盐酸中分别与铜单质、二价铜离子、氯化铁溶液的反应*

通过实验发现:SO₂在盐酸中既能将Cu单质氧化为+1价铜的化合物,也能把Cu²⁺还原为+1价铜的化合物,且发现SO₂将Cu单质氧化或将Cu²⁺还原都需要有Cl^-来参与反应,其反应机理需要通过SO₂和FeCl₃的反应(I^-催化)来进一步探究。这几个探究实验皆易于操作与观察,具有显著的实验表征,有利于从宏观辨识深入到微观探析的过程。     

Preparation and stability of copper particles formed using the template of hyperbranched poly(amine-ester)

The sixth-generation hydroxyl-ended hyperbranched poly(amine-ester) (G6-OH) was investigated as template in formation and stabilization of copper nanoparticles. Ultra-violet spectra and transmission electron microscope were adopted to characterize absorption properties of G6-OH(Cu²⁺)_n complex and the morphology of the formed particles (G6-OH(Cu)_n), respectively. The template and stabilization functions of G6-OH were compared with di-block copolymer micelles and dendrimers having similar structure. It was found that the hyperbranched polymers could act as the templates for the preparation of copper particles. The size of the formed copper particles increased with Cu²⁺/Gn-OH molar ratio. Besides, the oxygen influenced the chemistry stability of copper particles greatly.     

Preparation of Shell-Core Cu(2)O-Cu Nanocomposite Particles and Cu Nanoparticles in a New Microemulsion System

Shell–core Cu₂O–Cu nanocomposite particles and metal Cu nanoparticles are synthesized in a new microemulsion system which consists of saturated Cu²⁺ salt aqueous solution dispersed in isopropanol and stabilized by polyvinylalcohol (PVA). The size of the composite particles and the thickness of the Cu₂O shell layer can be controlled by the volume ratio of isopropanol to H₂O (the ratio is defined as R). When R ≥ 1000, it is available to obtain metal Cu nanoparticles.     

Hyperbranch-polyethyleniminated functional polymers II: effect of polyethyleniminated polyoxypropylenediamines on copper nanoparticle formation in aqueous solution

Colloidal aqueous solution of zerovalent copper (Cu(0)) nanoparticles were prepared from the Cu²⁺ ions coordinated with polyethyleniminated polyoxypropylenediamines (D400(EI) _x ) followed by chemical reduction of NaBH₄. Aqueous solution of copper clusters formed in the presence of D400(EI)₈ with a loading ratio of [EI]/[Cu²⁺] = 3 were stable without precipitation for standing more than 1 month. The protective effects of D400(EI) _x and the particle size of the resulted Cu nanoparticle are regulated by the attachments of ethylenimine (EI) groups per polymer backbone and the normality ratio of [EI]/[Cu²⁺] used. It is found that the more EI-content per polymer backbone results in the smaller particle size and the narrower size dispersity of the colloidal Cu(0) particles, and the average particle size of 5.07 nm with standard deviation of 0.86 nm was obtained in the presence of D400(EI)₈ with the ratio of [EI]/[Cu²⁺] = 3. As the polymer concentration of D400(EI)₈ increases (the increase of [EI]/[Cu²⁺]), the average particle size of the prepared Cu(0) nanoparticle slightly changes, but interestingly, the size dispersity gradually decreases, where the standard deviation for the concentration at [EI]/[Cu²⁺] = 5 is 0.82 nm approaching that for monodispersed nanoparticles (0.5 nm).     

微波辐射下2-芳氧甲基苯并咪唑类化合物的合成

以多聚磷酸和4 mol/L盐酸(PPA-HCl)作催化剂, 在微波辐射条件下合成了13种2-芳氧甲基苯并咪唑类化合物, 其中6种尚未见报道. 其结构经元素分析, IR, ¹H NMR, ¹³C NMR及MS确证. 与经典方法相比, 微波条件下的反应具有时间短、收率高等优点. 反应物邻苯二胺与芳氧基乙酸的物质的量比为1∶1.1, 催化剂PPA与HCl的最佳比例为1∶1(体积比), 最适宜的微波辐射功率为650～850 W, 反应时间为10～15 min.     

Dependence of Property of Silver Nanoparticles within Dendrimer-template on Molar Ratios of Ag+ to PAMAM Dendrimers

G5.0‐OH PAMAM dendrimers were used to prepare fluorescent silver clusters with weaker ultraviolet irradiation reduction method, in which the molar ratio of Ag⁺ to PAMAM dendrimers was the key factor to determine the geometry and properties of silver nanoparticles. The results showed that because of G5.0‐OH PAMAM dendrimers as strong encapsulatores, when the molar ratios of Ag⁺ to PAMAM dendrimers was smaller than 5, the obtained Ag_n clusters (n<5) had line structures and "molecular‐like" properties, which were highly fluorescent and quite stable in aqueous solution. Whereas when the molar ratios were between 5 and 8, the obtained Ag_n clusters were 2D structures and their fluorescence was weaker. When the molar ratio was larger than 8, the structure of silver nanoparticles was 3D and no fluorescence was observed from the obtained silver nanoparticles.     

Cu/活性炭催化剂：水合肼还原制备及催化甲醇氧化羰基化

以活性炭为载体,水合肼为还原剂制备了负载型Cu/活性炭催化剂,考察了水合肼/硝酸铜物质的量的比对催化甲醇气相氧化羰基化性能的影响,并采用XRD、XPS、H2-TPR和SEM等手段对催化剂进行了表征。结果表明,不加入还原剂水合肼时,催化剂中仅有CuO;随着水合肼/硝酸铜物质的量的比的增加,二价铜逐步被还原为Cu2O和/或单质Cu0,未被还原的Cu(OH)2在催化剂干燥过程中分解形成分散态CuO存在于催化剂表面。当水合肼/硝酸铜物质的量的比为0.75时,催化剂的催化性能最好,碳酸二甲酯的时空收率为120.62 mg.(g.h)-1,选择性为74.51%,甲醇转化率达到3.88%。在93 h反应时间内,催化剂都保持了较高的反应活性和选择性。此时铜物种以Cu2O和分散态CuO为主,Cu2O是主要的活性物种。     

Atomic‐Level Alloying and De‐alloying in Doped Gold Nanoparticles

Atomically precise alloying and de‐alloying processes for the formation of Ag–Au and Cu–Au nanoparticles of 25‐metal‐atom composition (referred to as Ag_xAu_25?x(SR)₁₈ and Cu_xAu_25?x(SR)₁₈, in which R=CH₂CH₂Ph) are reported. The identities of the particles were determined by matrix‐assisted laser desorption ionization mass spectroscopy (MALDI‐MS). Their structures were probed by fragmentation analysis in MALDI‐MS and comparison with the icosahedral structure of the homogold Au₂₅(SR)₁₈ nanoparticles (an icosahedral Au₁₃ core protected by a shell of Au₁₂(SR)₁₈). The Cu and Ag atoms were found to preferentially occupy the 13‐atom icosahedral sites, instead of the exterior shell. The number of Ag atoms in Ag_xAu_25?x(SR)₁₈ (x=0–8) was dependent on the molar ratio of Ag^I/Au^III precursors in the synthesis, whereas the number of Cu atoms in Cu_xAu_25?x(SR)₁₈ (x=0–4) was independent of the molar ratio of Cu^II/Au^III precursors applied. Interestingly, the Cu_xAu_25?x(SR)₁₈ nanoparticles show a spontaneous de‐alloying process over time, and the initially formed Cu_xAu_25?x(SR)₁₈ nanoparticles were converted to pure Au₂₅(SR)₁₈. This de‐alloying process was not observed in the case of alloyed Ag_xAu_25?x(SR)₁₈ nanoparticles. This contrast can be attributed to the stability difference between Cu_xAu_25?x(SR)₁₈ and Ag_xAu_25?x(SR)₁₈ nanoparticles. These alloyed nanoparticles are promising candidates for applications such as catalysis.     

Controllable Synthesis of Covellite Nanoparticles via Thermal Decomposition Method

In this study, covellite (CuS) nanoparticles were synthesized through a facile and low temperature thermal decomposition method using [Cu(sal)₂]- oleylamine complex, (sal = salicylaldehydeato, prepared in situ from [Cu(sal)₂] and oleylamine as the precursors), and sulfur as the Cu²⁺ source and S source, respectively. Scanning electron microscope, transmission electron microscope, electron diffraction and ultraviolet–visible absorption (UV–Vis) spectra were used for the characterization of the products. The effect of reaction parameters, such as the copper:sulfur molar ratio, the reaction temperature and the reaction time on the shape, size and phase of CuS nanostructures, was investigated. The results showed that the, covellite (hexagonal structure of CuS) with an average size between 20 and 45 nm could be obtained with the Cu:S molar ratio of 1: 3 at 105 °C for 60 min. With increasing the reaction temperature from 105 to 200 °C, non-stoichiometric Cu_1.65S with the average size of 25–50 nm was obtained due to the different existing state of the released Cu²⁺ ions from the copper-oleylamine complex.     

一种新型四氮杂取代三环冠醚的晶体结构及其配合物的合成与表征

合成了一种新型的四氮杂取代的三环结构冠醚4,13-二氧-1,7,10,16-四氮杂三环[14.2.1.1^7,10]二十烷(L7), 低温条件下在乙醚中培养出其单晶, 用X射线衍射法测定了晶体结构. 该晶体属单斜晶系, 空间群P2₁/n, 晶胞参数a＝0.8984(7) nm, b＝1.0805(9) nm, c＝1.1040(9) nm; Z＝2, β＝111.707(13)°; V＝0.9958(14) nm³, D_c＝1.189 g/cm³, μ＝0.092 mm^－1, F(000)＝392, R₁＝0.0649, wR₂＝0.1714. 制备了配体L7与金属盐的配合物, 分析结果表明, 配体L7与金属离子形成1∶1型的配合物.     

Characteristics of copper sulfide nanoparticles obtained in the copper sulfate–sodium thiosulfate system

Stable hydrosols of copper sulfide nanoparticles are synthesized by heating aqueous solutions with different ratios of sodium thiosulfate and copper sulfate in the presence of polyvinylpyrrolidone and studied by a number of physicochemical methods in situ (optical spectroscopy, dynamic light scattering) and ex situ (transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy). The main product is CuS covellite nanoparticles with some impurities of other phases (Cu₂S, Cu_1,8S, Cu₇S₄). With an increase in the initial molar ratio S₂O ^2?₃ / Cu from 0.2 to 5 the nanoparticle size increases from 1-5 nm to 30-50 nm and then decreases to 4 nm at a ratio of 10. A substantial increase in the intensity of plasmon absorption within 800-1500 nm is observed during the formation of planar nanoparticles with a lateral size of about 30 nm at S₂O ^2?₃:Cu = 5. A band gap obtained from both direct and indirect optical absorption spectra of sulfides (2.6 eV and 1.7 eV respectively) remains constant for all particles.