Cu_2O@HKUST-1前驱物法合成CuO中空管状超级结构及其CO催化氧化性能

以Cu_2O@HKUST-1(HKUST-1=Cu_3(BTC)2,BTC~(3-)=均苯三甲酸离子)线状核@壳结构为前驱体,通过在碱性条件下原位水解HKUST-1壳、氧化刻蚀Cu_2O核的方法得到了一种新型的、由相互交错的CuO纳米片构筑的、中空管状的超级结构,并研究了其对CO氧化的催化活性。结果表明,这种中空的CuO管状超级结构具有较大的比表面积(56.3 m~2/g)和可观的催化活性,催化剂对CO的完全转化温度为200℃,190℃时转化效率为17.3 mmolCO/(gCuO·h)。     

不同金属负载对Cr/Al2O3-TiO2催化剂结构及氧化NO性能的影响

采用溶胶-凝胶法和浸渍法制备Cr/Al_2O_3-TiO_2催化剂,在考察不同Cr负载量的基础上,研究不同金属负载与焙烧温度对Cr/Al_2O_3-TiO_2催化剂结构与性能影响。程序升温氧化(TPO)结果表明,当Cr负载量为10%(w/w)时具有较好的催化活性;不同金属负载Cr/Al_2O_3-TiO_2时,负载Co及在焙烧温度为550℃时催化剂具有较好的活性。通过程序升温还原(H_2-TPR)表征发现,Co的负载使催化剂的低温氧化还原能力逐渐提高,表明Co-Cr具有较好的协同催化作用。X射线光电子能谱(XPS)表征表明,Co增加了Cr~(6+)和表面吸附氧(O_β)含量,随着焙烧温度的升高(450～550℃),晶格氧不断向催化剂表面流动,表面化学吸附氧O_β比例逐渐增加,导致催化活性不断升高,说明Cr~(6+)和O_β是催化氧化NO的重要活性物种。     

Co~(2+)/Cu~(2+)掺杂型铋杂多酸的制备及催化烯烃的研究

以多功能无毒且环境友好的铋(Bi~Ⅲ)为杂原子制备了Na_(12)[Bi_2W_(22)O_(74)(OH_)2]·42H_2O(Bi-POM)、Na_(10)[Bi_2W_(20)Co_2O_(70)(H_2O)_6]·39H_2O(Bi-Co-POM)以及Na_8[Bi_2W_(20)Cu_2O_(68)(OH)_2(H_2O)_6]·25H_2O(Bi-Cu-POM)含铋杂多酸催化剂,并用于以分子氧为氧化剂催化环己烯转化为环己烯酮的羰基化反应。这些复合物通过FT-IR、UV、TG/DSC以及XRD等分析方法对其结构进行了表征。结果表明Bi-POM催化剂对环己烯烯丙位羰基化反应具有较高的催化活性,掺杂Co~(2+)或Cu~(2+)金属离子后催化活性进一步提升。Bi-Co-POM催化剂展示了最优的催化性能,在最佳反应条件下(O_2氛围,60℃,8 h),催化氧化环己烯(作为模板)转化率高达85.9%,2-环己烯-1-酮的选择性高达91.6%。并探究了Bi-Co-POM催化剂在最优条件下对不同反应底物的普遍适用性,提出了可能的催化氧化机理。     

NiO-MoO_3/γ-Al_2O_3催化剂硫化过程研究

利用TPR(程序升温还原)、TPS(程序升温硫化)及恒温还原硫化技术研究了实验室制备的NiO-MoO_3/γ-Al_2O_3催化剂在不同硫化剂(H_2S、CS_2)硫化过程中的反应情形。实验结果表明,H_2S容易硫化氧化态样品,而CS_2/H_2容易硫化还原态样品。提出了还原硫化反应机理——H_2S可以直接通过S—O交换硫化样品,CS_2/H_2需要被加氢生成H_2S,再以后者硫化样品。CS_2/H_2的硫化过程是先还原后硫化。提出了以CS_2/H_2作硫化剂的硫化程序。     

Mn-Al和Cu-Mn-Al复合氧化物催化苯甲醇选择氧化反应

用溶胶-凝胶法制备了不同组成的Mn-Al和Cu-Mn-Al复合氧化物两组催化剂,用于苯甲醇选择氧化反应.用X射线衍射(XRD)、N2物理吸附(BET)、扫描电镜(SEM)、H_2程序升温还原(H_2-TPR)、O_2程序升温脱附(O_2-TPD)和X射线光电子能谱(XPS)技术对催化剂进行了结构表征,考察了催化剂组成对催化活性的影响.结果表明:以甲苯为溶剂,O_2为氧化剂,353 K反应5 h,Mn_2Al和Cu_(0.3)Mn_(0.7)Al_2催化剂上的苯甲醇转化率分别为36.6%和40.9%,苯甲醛选择性均为100%.进一步研究表明:催化剂活性与其H2还原性和O_2吸附性有关,高活性的催化剂吸附氧多,生成的活性氧易参与反应.     

不同表面形貌Cu2O空心球的制备及光催化性能

采用一步溶剂热法,以Cu(NO_3)_2·3H_2O为铜源,乙二醇(EG)为还原剂,聚乙烯吡咯烷酮(PVP)为表面活性剂,高温条件下制备形貌可控的Cu_2O空心球纳米材料。研究Cu(NO_3)_2·3H_2O与PVP的质量比值(w_(Cu(NO_3)_2·3H_2O)/w_(PVP))对Cu2O结构、形貌、比表面积以及光吸收特性的影响,并结合光催化机理讨论其对Cu_2O光催化性能的影响。此外,通过改变反应时间来研究Cu_2O的生长过程。结果表明,w_(Cu(NO_3)_2·3H_2O)/w_(PVP)=45时,得到的形貌为空心球表面覆盖纳米刺的Cu_2O纳米材料光催化性能最佳,在可见光辐照10 min的条件下,对甲基橙的降解率达94.3%。     

Cu-MOF催化过氧化氢应用于多巴胺的检测

本文利用一种具有H_2O_2催化活性的Cu-MOF[Cu_3(BTC)_2(H_2O)_3,简称HKUST-1],构建了以邻苯二胺(OPD)为颜色指示分子的比色传感体系,实现了对H_2O_2和多巴胺(DA)的快速灵敏检测。HKUST-1起到催化H_2O_2氧化OPD的作用,反应体系能够呈现出显著的颜色变化。在优化条件下,415nm处的吸收峰强度与H_2O_2浓度呈双线性关系,线性范围分别为10~50 mmol/L和50~100 mmol/L,相对标准偏差分别为0.9947和0.9995,最低检出限为1.29mmol/L。由于DA能抑制H_2O_2氧化OPD,因此比色传感体系还可以用于快速检测DA,线性范围分别为0.25~5μmol/L和2.5~25μmol/L,相对标准偏差分别为0.9783和0.9705,最低检出限为0.262μmol/L。该项工作拓展了Cu-MOFs材料在生物分子催化和生物传感方面的应用。     

NiFe2O4磁性纳米材料的溶剂热法一步合成

以Fe(NO_3)_3·9H_2O和Ni(NO_3)_2·6H_2O为原料,在未添加任何碱性沉淀剂和高温晶化处理的条件下,通过对实验条件(包括溶剂、溶剂热温度和时间)的优化,利用溶剂热法一步制备了具有良好结晶性和超顺磁性的NiFe_2O_4磁性纳米材料。结果表明:用H_2O和EtOH-H_2O做溶剂都不利于NiFe_2O_4的生成;用EtOH做溶剂,为了获得纯度较高的NiFe_2O_4磁性纳米材料,要保证适当的溶剂热温度和时间;所得材料的磁性能与材料中磁性组分NiFe_2O_4的含量和其结晶程度有关。该制备方法最突出的优点是简单、快速、成本低、从源头消除了污染,且所得的材料磁性能优良。     

核壳结构纳米Cu_2O/Ag的制备、表征和应用研究

通过溶胶-凝胶法制备了单分散性的球形纳米Cu_2O,采用取代反应法在上面负载一层纳米Ag,制备了核壳结构的Cu_2O/Ag纳米复合材料。利用透射电镜(TEM)分析了纳米Cu_2O/Ag的形貌,并用X射线衍射测(XRD)X射线光电子能谱(XPS)分析了其物相组成,利用紫外-可见光谱(UV-Vis)和光致发光光谱(PL)研究了其光谱特征,以罗丹明B(Rh B)为模型污染物,在紫外光照射下评价了纳米Cu_2O/Ag的光催化活性。结果表明:Cu_2O平均直径为150nm,表面纳米银直径为7nm,形成核壳结构;光催化结果显示,银沉积显著提高了Cu_2O的光催化活性。     

Pt@Au/Al_2O_3核壳纳米粒子的制备和表征及其在催化氧化甲苯中的应用（英文）

采用种子生长法,在不存在保护剂和结构导向剂的情况下,成功制备Pt@Au核壳结构纳米颗粒,即在Pt纳米颗粒表面,Au Cl~(4-)被H_2还原成Au(0),并沉积在Pt核纳米颗粒上。通过透射电子显微镜(TEM),能量色散X射线光谱(EDS),高分辨率TEM (HRTEM),傅里叶变换(FFT)和X射线粉末衍射(XRD),X射线光电子能谱(XPS),红外光谱(IR)和H_2-程序升温还原(H_2-TPR)等表征证实了核壳结构。所制得的Pt@Au_x/Al_2O_3催化剂在常压下由固定床反应器测定其在甲苯氧化中的活性。相比于单金属催化剂Pt/Al_2O_3与Au/Al_2O_3,Pt@Au_x/Al_2O_3核壳催化剂显示出更高的催化活性,且Pt_1@Au_1/Al_2O_3对于甲苯氧化具有最好的催化活性,这归因于Au和Pt之间的电子交换促进了Au上活性氧的形成。Pt@Au_x/Al_2O_3对甲苯氧化良好的催化性能和高选择性与其较高的吸附氧物质浓度,较好的低温还原性和强相互作用有关。     

TPR investigations on the reducibility of Cu supported on Al2O3, zeolite Y and SAPO-5

Reducibility of Cu supported on Al₂O₃, zeolite Y and silicoaluminophosphate SAPO-5 has been investigated in dependence on the Cu content using a method combining conventional temperature programmed reduction (TPR) by hydrogen with reoxidation in N₂O followed by a second the so-called surface-TPR (s-TPR). The method enables discrimination and a quantitative estimation of the Cu oxidation states +2, +1 and 0. The quantitative results show that the initial oxidation state of Cu after calcination in air at 400 °C, independent on the nature of the support, is predominantly +2. Cu²⁺ supported on Al₂O₃ is quantitatively reduced by hydrogen to metallic Cu⁰. Comparing the TPR of the samples calcined in air and that of samples additionally pre-treated in argon reveals that in zeolite Y and SAPO-5 Cu²⁺ cations are stabilized as weakly and strongly forms. In both systems, strongly stabilized Cu²⁺ ions are not auto-reduced by pre-treatment in argon at 650 °C, but are reduced in hydrogen to form Cu⁺. The weakly stabilized Cu²⁺ ions, in contrast, may be auto-reduced by pre-treatment in argon at 650 °C forming Cu⁺ but are reduced in hydrogen to metallic Cu⁰.     

Effect of synthesis solution pH of Co/γ-Al_2O_3 catalyst on its catalytic properties for methane conversion to syngas

The cobalt nanoparticles over γ-Al_2O_3 support were prepared via chemical reduction of CoCl_2·6H_2O using NaBH_4 with various values of pH in the range of 11. 92-13. 80. Synthesized catalysts were studied through X-ray diffraction( XRD),N_2 adsorption/desorption( BET),H_2-temperature programmed reduction( H_2-TPR),H_2-chemisorption,O_2 pulse titration and temperature programmed oxidation( TPO) methods. Obtained results exhibited the synthesis solution pH showed a significant influence on the activity and selectivity in partial oxidation of methane reaction. The methane conversion,CO selectivity and H_2 yield were enhanced by increasing of the synthesis solution pH. Compared to other catalysts,the catalyst that synthesized at pH of 13.80,showed a superior ability in syngas production with a H_2/CO ratio of near 2 and also a proper stability against deactivation during the partial oxidation of methane.     

Study on the Phenolic Oxidation by H2O2 Using Metallomicelles Composed of Dinuclear Copper(II) Complex as Synthetic Peroxidases

A dinuclear copper(II) complex [Cu₂(oxheel)] was synthesized and its structure was analyzed. This compound was then mixed with a surfactant (Brij35 or LSS) to form a metallomicelle, which would catalyze the phenol oxidation with the hydrogen peroxide (H₂O₂). The reaction mechanism and the mathematic model for the kinetics of this reaction were proposed, and the effect of the molar ratio between H₂O₂ and catalyst, of the temperature and of the pH levels on the rate of catalytic reaction were studied.     

Low-Temperature H2 Reduction of Copper Oxide Subnanoparticles

Subnanoparticles (SNPs) with sizes of approximately 1 nm are attractive for enhancing the catalytic performance of transition metals and their oxides. Such SNPs are of particular interest as redox-active catalysts in selective oxidation reactions. However, the electronic states and oxophilicity of copper oxide SNPs are still a subject of debate in terms of their redox properties during oxidation reactions for hydrocarbons. In this work, in situ X-ray absorption fine structure (XAFS) measurements of Cu₂₈O_x SNPs, which were prepared by using a dendritic phenylazomethine template, during temperature-programmed reduction (TPR) with H₂ achieved lowering of the temperature (T₅₀=138 °C) reported thus far for the Cu^II→Cu^I reduction reaction because of Cu−O bond elongation in the ultrasmall copper oxide particles.     

Spectrofluorimetric determination of hydrogen peroxide scavenging activity

Homovanillic acid (HVA) is widely used for the detection and imaging of oxidative enzymes—peroxidase, glucose oxidase and xanthine oxidase, but antioxidant activity has not been determined so far with the use of HVA. We have developed a simple, sensitive and in-field spectrofluorimetric method for the determination of hydrogen peroxide (H₂O₂) scavenging activity. The assay is based on the oxidation of HVA to its fluorescent biphenyl dimer in the presence of H₂O₂ and peroxidase. The presence of substances with H₂O₂ scavenging activity prevents the oxidation of HVA by removing H₂O₂. The decrease in fluorescence intensity is proportional to the antioxidative (H₂O₂ scavenging) activity. The method was evaluated using Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid), BHA (3-t-butyl-4-hydroxyanisole) and ferulic, vanillic, caffeic, chlorogenic, protocatechuic and oxalic acids. Additionally, tea and herb infusions known for their antioxidant properties were evaluated.     

CuFe-SAPO-34分子筛的结构和催化性能研究

采用一步水热合成法,通过调变初始凝胶中的硅铁比,制备系列铜铁含量不同的CuFe-SAPO-34催化剂用于NH₃选择性催化还原NO_x反应（NH₃-SCR）,并采用ICP、XRD、SEM、BET、H₂-TPR等方法对其结构进行表征.结果表明,CuFe-SAPO-34催化剂具有典型的CHA结构,Cu和Fe均处于分子筛载体的离子交换位.当初始凝胶SiO₂/Fe₂O₃=10时,Cu_2.5Fe_3.1-SAPO-34催化剂具有最大的比表面积和孔容.掺杂适量的Fe,可提高活性物种Cu²⁺的比例及其氧化还原性能,显著降低Cu物种的聚集程度.NH₃-SCR反应结果表明,Cu_2.5Fe_3.1-SAPO-34催化剂具有最宽的反应温度窗口.与Cu-SAPO-34相比,Fe的掺杂显著提高了其高温段的催化活性和低温抗水能力,提高了Cu-CHA催化剂在实际应用中的稳定性.     

Chemical Fixation of CO2 and Other Heterogeneous Catalytic Studies by Employing a Layered Cu‐Porphyrin Prepared Through Single‐Crystal to Single‐Crystal Exchange of a Zn Analogue

A solvothermal reaction of Zn(NO₃)₂ ? 6 H₂O, tetra‐(4‐pyridyl)porphyrin (H₂TPyP), and 4,4′‐oxybis(benzoic acid) (H₂OBA) resulted in a new two‐dimensional Zn‐ porphyrin metal–organic framework compound, [Zn₂(C₄₀H₂₄N₈)_0.5(C₁₄H₈O₅)(DMA)](DMA)(H₂O)₆ ( 1 ; DMA=N,N‐dimethylacetamide). The Zn^II ions present in 1 could be exchanged by using a solution of Cu(NO₃)₂ ? 3 H₂O in DMA at room temperature to give [Cu₂(C₄₀H₂₄N₈)_0.5(C₁₄H₈O₅)(DMA)](DMA)(H₂O)₃ ( Cu∈1 ). The extra‐framework solvent molecules have been shown to be reversibly removed or exchanged without collapse of the framework. Solvent‐free Cu∈1 was explored as an active heterogeneous catalyst towards three different organic reactions: 1) the chemical fixation of CO₂ into cyclic carbonate at room temperature and 1 atm; 2) the nitroaldol reaction under solvent‐free conditions, and 3) the three‐component coupling of aminopyridine, benzaldehyde, and aryl alkynes followed by 5‐exo‐dig cyclization to produce the important pharmacophore imidazopyridine.     

Copper(II) complexes with hydroxyl-containing dipeptides glycyl- L -serine and L -seryl- L -tyrosine

Dipeptides glycyl- _L -serine and _L -seryl– _L -tyrosine are tridentate ligands in coordination with Cu(II) through their NH₂?, N–(from deprotonated amide group) and O–atom (by COO- group), forming [Cu^II(LH_?1)H₂O]. The forth position of square-planar geometry of Cu²⁺ is occupied by H₂O as terminal ligand. Solid-state linear dichroic IR-spectroscopy, UV-Vis, mass spectrometry with ESI and FAB, tandem mass spectrometry (HPLC-MS/MS), TGV and DSC methods, EPR and magnetochemistry data prove the formation of five-membered chelate rings with participation of Cu²⁺ both in solution and in solid state.