高活性Au/SnO2催化剂的制备及其在1,4-丁二醇氧化制γ-丁内酯反应中的催化应用

采用沉积沉淀法制备了一系列商业SnO₂负载的纳米Au催化剂, 通过电感耦合等离子体发射光谱、X射线粉末衍射、透射电镜和X射线光电子能谱等方法研究了溶液酸碱性、沉淀剂种类、Au负载量和焙烧温度等对催化剂性质的影响.结果表明, Au的负载量以及催化剂的焙烧温度对Au颗粒状态有较大影响.其中, 于573 K焙烧的3%Au/SnO₂催化剂在1,4-丁二醇氧化制备γ-丁内酯反应中的催化活性最好, TOF值是Au/TiO₂催化剂的15倍.这主要是由于SnO₂载体独特的性质对所负载的Au颗粒的影响.     

高比表面介孔LaNiO3负载纳米Au催化剂的研究

分别采用纳米铸型法和溶胶-凝胶法制备了系列LaNiO₃载体,并用沉积-沉淀法制备了系列Au/LaNiO₃催化剂.对催化剂进行了XRD、BET、AAS、TEM和XPS等表征,测试了其对CO催化氧化活性.实验结果表明,纳米铸型法得到的LaNiO₃-NCM具有介孔结构,且比表面积可达126 m²·g^-1,以其为载体制备的Au/LaNiO₃-NCM催化剂在30℃条件下将CO完全转化,活性远高于以传统溶胶-凝胶法制备的LaNiO₃-SG为载体的金催化剂.XPS结果表明该Au/LaNiO₃-NCM催化剂表面存在较多的氧化态Au^δ+（0 < δ < 3）和晶格氧,且活性组分Au含量也较高,说明高比表面介孔LaNiO₃载体有利于提高活性组分Au的负载量,从而提高催化剂催化活性.     

Pt/TiO2催化剂上CO氧化反应动力学研究

利用沉积沉淀法制备了Pt/TiO₂催化剂, 将其在不同温度下焙烧, 以得到不同颗粒尺寸的Pt. 并将这些样品用于CO催化氧化反应以及反应动力学研究. 结果表明: 焙烧温度对催化剂有明显影响, Pt 颗粒尺寸随着焙烧温度的升高而增加; 与此同时, CO催化活性随焙烧温度的升高呈先增加后降低的趋势, 其中, 400℃焙烧的样品表现出最高的催化活性. 反应动力学结果表明, 催化剂上CO氧化反应表观速率方程为r=5.4×10^-7p_CO^0.17p_O2^0.36,说明在该催化剂上CO氧化遵循Langmuir-Hinshelwood机理. 同时, 对催化剂进行了CO化学吸附红外光谱和O₂化学吸附表征. 结果表明, 随着焙烧温度的升高, 催化剂上CO和O₂吸附量均呈现先升高后降低的趋势, 这与反应结果和反应动力学方程一致, 说明反应受到催化剂表面上CO和O₂吸附浓度的影响. 而在400℃焙烧的催化剂上, CO和O₂吸附量均最高, 因此其反应活性也最好. 这可能是焙烧过程影响了Pt 和TiO₂之间的相互作用引起的.     

焙烧温度对MnOx-CeO2-WO3-ZrO2催化剂上NH3选择性还原NO的影响

采用共沉淀法制备了MnO_x-CeO₂-WO₃-ZrO₂催化剂,考察了催化剂焙烧温度对O₂和H₂O存在下NH₃选择性催化还原（NH₃-SCR） NO的影响,并利用低温N₂吸附、X射线衍射（XRD）、透射电镜（TEM）、X射线光电子能谱（XPS）、NH₃程序升温脱附（NH₃-TPD）和CO脉冲反应对催化剂进行了表征. 结果表明在NH₃-SCR反应中,催化剂的低温活性随焙烧温度的提高而降低,这是由于催化剂表面化学吸附氧和酸性位减少引起的;催化剂的高温活性随焙烧温度的提高先增加后减小,这与催化剂表面最易释放氧数量的变化趋势相反. 700 ℃焙烧的催化剂具有良好的低温活性和最宽的反应温度窗口,在空速为90000 h^-1的条件下,该催化剂的起燃温度（50% NO转化率）为189 ℃,且反应温度在218-431 ℃范围内,NO转化率可达到80%-100%.     

焙烧温度对“软-硬”模板法制备的Pd/Ce0.65Zr0.35O2三效催化性能的影响

采用"软-硬"模板法制备了具有高热稳定性的Ce_0.65Zr_0.35O₂（CeZr）。考察了制备过程中焙烧温度对Ce_0.65Zr_0.35O₂及其负载的单Pd三效催化剂（TWC）性能的影响。对样品进行了X射线衍射、比表面、拉曼光谱、X射线光电子能谱、储氧性能和H₂程序升温还原性能测试。结果表明：焙烧温度显著影响催化剂的结构和性能。随着焙烧温度的增加，Ce_0.65Zr_0.35O₂的比表面下降，但在1 000℃焙烧的样品比表面为61 m²·g^-1，显著高于同温度下直接在空气中焙烧的样品。由于高温导致了物相重组，Ce_0.65Zr_0.35O₂的储氧量和还原性能随着焙烧温度的增加而提升。由于高温烧结导致Pd分散性的下降，其负载的催化剂的还原性能随着焙烧温度的增加而下降，从而最终导致催化剂活性的降低。但在"软-硬"模板法中1 000℃焙烧的样品负载的催化剂依然显示出很好的三效催化性能，该催化剂上C₃H₈、CO和NO的起燃温度分别为274、175和133℃，显著低于同温度下空气中直接焙烧的样品负载的催化剂。催化剂的氧化还原性能和Pd的分散性是影响催化活性的主要因素。     

Au/γ-MnO2催化剂催化无溶剂条件下甲苯氧化反应

采用氧化还原法制备了α, δ, γ-MnO₂载体, 采用原位还原法制备了Au负载量为0.5%-3.0%的Au/γ-MnO₂催化剂, 并采用X射线衍射、扫描电镜、透射电镜和N₂物理吸附等手段对其进行了表征. 透射电镜照片表明Au/γ-MnO₂催化剂中Au颗粒的大小约为10 nm. 采用无溶剂存在下的甲苯氧化反应测试所制备样品的催化活性. 结果表明, 甲苯转化率随着Au负载量的增加而增大. 这是由于Au颗粒数量增多, 尺寸减小的缘故. 同时, 负载Au颗粒对苯甲醛具有较高的选择性. Au/γ-MnO₂催化剂具有良好的重复使用性.     

Cu含量对Pd-Cu/铝土矿CO氧化催化剂结构和性能的影响

利用资源丰富的天然铝土矿经NaOH溶液水热处理后焙烧,获得比表面积达174 m²·g^-1铝土矿载体,制备了双金属Pd-Cu为活性组分的催化剂,金属Pd负载量为0.5%（质量百分数）,以CO氧化反应为探针反应,详细考察了Cu含量的变化对催化剂物化性能的影响。研究发现,Cu的引入有利于提高金属Pd的分散度,同时随着Cu含量的变化,金属Pd与Cu之间以及金属与铝土矿载体之间的相互作用随之改变。催化剂的CO氧化反应性能评价结果表明,Pd和Cu负载量分别为0.5%和4%的样品（PdCu₄/MB）催化反应性能最佳。结合表征结果认为,PdCu₄/MB的高活性归因于良好的Pd和Cu分散度,金属Pd、Cu以及金属与载体之间较强的相互作用。此外,CO-TPD表征结果说明较强的CO吸附能力和从载体中获取氧的能力也有利于提高PdCu₄/MB样品的CO氧化反应性能。     

Cu含量对Pd-Cu/铝土矿CO氧化催化剂结构和性能的影响

利用资源丰富的天然铝土矿经NaOH溶液水热处理后焙烧,获得比表面积达174 m²·g^-1铝土矿载体,制备了双金属Pd-Cu为活性组分的催化剂,金属Pd负载量为0.5%（质量百分数）,以CO氧化反应为探针反应,详细考察了Cu含量的变化对催化剂物化性能的影响。研究发现,Cu的引入有利于提高金属Pd的分散度,同时随着Cu含量的变化,金属Pd与Cu之间以及金属与铝土矿载体之间的相互作用随之改变。催化剂的CO氧化反应性能评价结果表明,Pd和Cu负载量分别为0.5%和4%的样品（PdCu₄/MB）催化反应性能最佳。结合表征结果认为,PdCu₄/MB的高活性归因于良好的Pd和Cu分散度,金属Pd、Cu以及金属与载体之间较强的相互作用。此外,CO-TPD表征结果说明较强的CO吸附能力和从载体中获取氧的能力也有利于提高PdCu₄/MB样品的CO氧化反应性能。     

超声法制备Au/Fe3O4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe₃O₄催化剂。利用3-氨丙基三乙氧基硅烷（APTES）作为有机桥键,将Au固定在Fe₃O₄的表面,得到单分散磁性Au/Fe₃O₄。Au⁰在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe₃O₄已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min^-1。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

在一维ZnO表面可控构建Co3Mn1纳米晶及其催化CO氧化性能

利用热分解法制备了结构明确的负载型纳米晶催化剂。在纳米晶成核和生长过程中加入一维ZnO纳米棒作为晶种,调控不同组分的纳米晶在 ZnO纳米棒表面均匀生长,从而获得了结构明确的 MnO/ZnO、Co₃O₄/ZnO、Co₃Mn₁/ZnO催化剂。透射电子显微镜(TEM)与 X 射线粉末衍射(XRD)结果显示,不同组分纳米颗粒都均匀分散在 ZnO 纳米棒表面。相对于 MnO/ZnO 和Co₃O₄/ZnO催化剂,Co₃Mn₁/ZnO催化剂在CO氧化反应中具有最佳的催化性能。在200 L·g_cat^-1·h^-1的气时空速下,Co₃Mn₁/ZnO催化剂起活温度为 50 ℃,其 T100(CO 转化率达到 100% 时的温度)为 200 ℃;利用 X 射线光电子能谱(XPS)对不同催化剂进行了分析,结果显示,Co₃Mn₁/ZnO催化剂的氧空位比MnO/ZnO催化剂提高了30%以上,从而使其具有较高的CO氧化催化性能。更为重要的是,Co₃Mn₁/ZnO复合纳米晶催化剂的活化能(39.4 kJ·mol^-1)远低于其它负载型纳米晶催化剂。     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/₂, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of⁹⁹Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/₃, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

Direct synthesis of dimethyl carbonate ?from CH3OH AND CO2 by H3PW12O40/CexTi1-xO2 catalyst

Summary Ce_xTi_1-xO₂ and H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ showed a better catalytic performance than the corresponding Ce_xTi_1-xO₂, due to the bifunctional catalysis of Br?nsted acid sites (provided by H₃PW₁₂O₄₀) and base sites (provided by Ce_xTi_1-xO₂). H₃PW₁₂O₄₀/Ce_0.1Ti_0.9O₂ showed the highest catalytic performance among the H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts.     

Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

LixNi0.8-yCo0.2ZnyOp的合成及电化学性能研究

A series of single-phase Li_xNi_0.8-yCo_0.2Zn_yO_p(0.96 ≤x≤ 1.10， 0 ≤y≤ 0.05， 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method， in which LiOH·H₂O， Zn-doped spherical Ni(OH)₂ and Co₂O₃ were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD， SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine， narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity， but also a better cycling stability characterization than the un-doped one. The Li_1.06Ni_0.75Co_0.22Zn_0.03O_2.03 material has an initial reversible capacity as high as 160.5mAh·g^-1; and a first discharge efficiency 89.2%， and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles.     

An investigation of the promotional effect of propylene or propane traces on the activity of sulfatedPt/g-Al2O3andPt-Sn/g-Al2O3inCH4combustion

Summary A strong promoting effect of the presence of C₃H₈or C₃H₆was determined for the combustion of CH₄in excess oxygen, over pre-sulfated 1%Pt/g-Al₂O₃and pre-sulfated 1%Pt-2%Sn/g-Al₂O₃catalysts.</o:p>     

Synthesis and characterization of Ti1−2xNbxNixO2−x/2 solid solutions

Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti_1−2xNb_xNi_xO_2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni²⁺ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO₂ powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO₂-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.).     

Visible light-sensitive yellow TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx anatase photocatalysts

Nitrogen substituted yellow colored anatase TiO_2−xN_x and Fe-N co-doped Ti_1−yFe_yO_2−xN_x have been easily synthesized by novel hydrazine method. White anatase TiO_2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe³⁺ in the lattice. TiO_2−xN_x has higher conductivity than TiO_2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO_2−x extends in the visible region in N, Fe and Fe-N co-doped TiO₂, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO₂ and Fe-doped TiO₂ show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO₂ consist may cause this discrepancy in their photocatalytic activities.     

LixZryOz三元化合物的制备及表征

采用高温固相法制备了4种高纯度晶相组成的LixZryOz三元化合物,研究了焙烧温度、时间、反应物的种类和初始反应物物质的量比对产物组成的影响,进一步用XRD、SEM及BET分析方法对产物的晶相结构、表面形貌及比表面积进行了表征.实验结果表明,Li2CO3与ZrO2在适当条件下可以合成得到单斜相Li3ZrO3;以LiOH替代Li2CO3,在适当条件下可以分别合成得到四方相Li2ZrO3和三斜/单斜相Li6Zr2O7;进一步以Zr(NO3)4·5H2O代替Zr02,可将单斜相Li6Zr2O7的制备时间由96 h缩短至24 h.SEM照片显示产物硬团聚明显,粒径分布在1～10μm间,BET分析表明样品比表面积处于1.0～9.0 m2·g-1间分布,反应过程中锂的过量以及长时间高温焙烧是引起产物粒径长大和产生硬团聚的主要原因.