Cr-MnO_x/堇青石催化剂制备及催化降解邻二氯苯性能研究（英文）

采用溶胶凝胶法、浸渍法、共沉淀法以及流变相法制备了新型Cr-MnO_x/堇青石催化剂,同时采用X射线衍射(XRD)、扫描电镜(SEM)、热重和差热分析(TG-DTA)、H_2-程序升温还原(H_2-TPR)以及元素能谱(EDS)技术对催化剂进行表征。经筛选发现,以共沉淀法制备的Cr-MnO_x/堇青石催化剂(Cr/Mn=2∶5)催化活性最高。通过表征结果可知,以共沉淀方法制备的催化剂主要活性成分为Mn_2O_3和Cr_2O_3,并且具有特殊的球形和较好的氧化还原性能,协同作用的存在有助于催化降解目标污染物邻二氯苯(o-DCB)性能的提高;在60h之内,o-DCB降解率仍保持在80%以上,具有较好的催化稳定性。     

不同制备工艺钒系SCR催化剂理化及催化性能研究

本文研究了制备工艺对 TiO2-WO3-V2O5- 载体型催化剂理化特性及其在 NH3-SCR 反应中催化性能的影响.通过 XRD、TG/DTA 等分析方法考察了煅烧温度等对催化剂中各组分晶体结构的影响,确定了制备负载型催化剂的最佳煅烧温度为 500℃.不同制备工艺催化剂理化性能的对比表明,多步浸渍法不仅提高了锐钛矿型 TiO2 向金红石型 TiO2 的转变温度,而且使更多的钒氧化物处于较低的价态,有利于提高还原反应的催化性能;催化活性评价试验也表明使用多步浸渍法制备的 SCR 催化剂具有较高的催化活性和更宽的高活性反应温度窗口.最后考察了反应空速对多步浸渍法所制备催化剂 NOx 转化效率的影响,结果表明:随空速的增加,NOx 转化效率逐渐降低.     

环境友好催化剂HPA/ZrO2-TiO2的制备及催化性能研究

制备了新型负载型杂多酸HPA/ZrO2-TiO2环境友好催化剂,用IR、UV和XRD手段研究了其结构形态;并考察了催化剂对合成乙酸异丙酯的应用研究。结果表明,HPA/ZrO2-TiO2仍然保持着Keggin型阴离子的特征结构,HPA和ZrO2-TiO2之间存在着强烈的化学作用,对合成乙酸异丙酯有很好的催化活性;在最佳反应条件下,酯收率为93.5%,催化剂重复使用5次后酯收率仍高达90.5%。     

葡萄糖催化氧化反应用Pd-Co/C催化剂的XPS研究

活性炭为载体，制备了Pd/C、Pd-Co/C催化剂，并进行了活性评价和XPS表征。在Pd-Co／C催化剂上反应3h后，葡萄糖的转化率达92％，选择性为94％，较Pd/C催化剂有显著提高。Co的添加及焙烧过程改变了Pd/C催化剂的表面组成及结构，提高了贵金属Pd在催化剂表面的分散程度，有利于Pd的还原，使Pd-Co/C催化剂表现出良好的催化活性和选择性。     

Ba/Fe-堇青石固溶体(Ba0.05Fe0.1Mg)2Al4Si5O18的组合筛选及红外辐射性能优化

采用组合材料方法制备并筛选了具有高红外辐射性能的Ba/Fe共掺堇青石固溶体(Ba_0.05Fe_0.1Mg)₂Al₄Si₅O₁₈. 通过组合溶液喷射法,制备了7×7阵列的样品库,并在不同温度下进行热处理.通过X射线衍射、红外热成像等测试方法分析了Ba²⁺、Fe³⁺固溶对堇青石晶格畸变和红外辐射性能的影响. 经过放大制备实验的验证,确定了材料的最佳组分为5%Ba²⁺和10%Fe³⁺共固溶的堇青石. 最佳组分样品在100 oC时的红外辐射率在5-24 μm波段均高于0.8.     

铁卟啉/钒取代杂多酸新型催化剂的合成、表征和性能研究

文章以水溶性碘化四对(4-三甲氨基苯基)铁卟啉和钒取代杂多酸H5PMo10V2O40为原料,采用离子交换方法在水溶液中合成了一种铁卟啉/钒取代杂多酸新型无机-有机复合催化剂,并使用红外和紫外光谱技术对其结构进行了表征,结果表明,这种新型复合催化剂仍然保持着卟啉的大环共轭结构和杂多酸的笼状多电子结构。同时研究了以30%过氧化氢水溶液为绿色氧化剂,初步探讨了这种铁卟啉杂多酸催化剂对苯的羟基化反应的的影响,考察了催化剂的催化活性。催化氧化实验表明,制备的铁卟啉/杂多酸配合物可用作苯直接氧化羟基化成苯酚的催化剂,并且表现出较高的催化活性。     

ZnO/BiOBr复合材料制备及可见光催化降解RhB性能研究

通过溶剂热法制备不同ZnO和BiOBr摩尔配比的ZnO/BiOBr复合光催化剂。ZnO与BiOBr摩尔比为1∶2时,ZnO/BiOBr复合材料光催化降解罗丹明B的性能最好,可见光照120 min,罗丹明B(20 mg/L)去除率达98.89%,降解速率常数为0.040 50 min^-1,是纯BiOBr的4倍。紫外-可见漫反射和荧光光谱分析显示较纯ZnO,ZnO/BiOBr(1∶2)吸收带红移,光子利用率提高,且光生电子-空穴复合机率降低。通过电子顺磁共振波谱仪和半导体能带理论对降解机理进行分析,结果显示降解过程主要通过·O₂^-、·OH自由基的氧化作用,ZnO与BiOBr之间形成界面电场,降低了电子-空穴的复合机会。     

BiOClxBryIz复合催化剂的制备及其可见光催化降解甲基橙

卤氧化铋由于具有特殊的层状结构和合适的禁带宽度而表现出了良好的可见光催化活性和稳定性,改变BiOXs中卤素的组成能调节禁带宽度,优化光催化性能.采用混合溶剂热法制备了一系列BiOClxBryIz(x,y,z=0.1,0.2,0.33,0.6,0.8)复合催化剂,首先对其结构形貌和光学特性进行了表征,然后在装有400 n...     

镍改性ZSM-5催化剂及其SCR催化性能

采用液态离子交换法制备了不同负载量的镍改性ZSM-5分子筛催化剂,并考察了上述催化剂的微观结构和物理化学特性及其在NH3-SCR反应中的催化性能。结果表明:在负载量<10.9%时镍在分子筛中具有高度的分散性,而随着镍负载量的进一步增加,分子筛表面开始出现较大的NiO颗粒;镍元素只以+2价存在于分子筛催化剂中;在NH₃-SCR反应中,镍负载量低于14.9%时,增加镍负载量将提高催化剂的低温活性;当反应温度超过300℃时,高温催化中心开始起作用,但随镍负载量的增加,高温活性开始下降时的温度逐渐降低。     

V2O5/WO3/TiO2催化剂制备及其SCR性能研究

本文通过浸渍法制备了V2O5/TiO2系列筛选催化剂及V2O5/WO3/TiO2负载型催化剂,并在模拟评价装置上考察了上述催化剂在SCR反应巾的催化性能.结果表明,V2O5在涂材料中应该低于3wt.%;钒系催化剂对NOx的净化效率随反应温度的升高,先增加而后减小,存在一个适宜反应温度窗口;随反应温度升高, NH3泄漏量逐渐降低,在温度达到350°C之后,NH3泄漏世不再随温度的升高而变化;SCR反应温度较低时HC和CO浓度基本不变,但从450°C开始,HC浓度逐渐降低,而CO浓度则急剧升高;随NOx/NH3比例增加,NOx转化效率逐渐降低.     

Preparation, characterization and magnetic properties of the doped barium hexaferrites BaFe12−2xCox/2Znx/2SnxO19, x=0.0-2.0

A series of powders of M-typed barium hexaferrites doped with Co, Zn and Sn of general formula BaFe_12-2xCo_x/2Zn_x/2Sn_xO₁₉ (x=0-2.0) were prepared by the co-precipitation/molten salt method. The structures, particle morphology and magnetic properties of the products were characterized by X-ray powder diffraction, vibrating sample magnetometer and ESEM/EDX. The results show that the crystallinity of the samples decreases with increase in the doping amount x. When x is less than 0.6, it is possible to obtain perfectly crystallized hexagonal BaFe_12-2xCo_x/2Zn_x/2Sn_xO₁₉, where the diameters of the particles are around 500 nm. The saturation magnetization of pure barium ferrite BaFe₁₂O₁₉ produced with this method is 71.9 A m² kg⁻¹ at room temperature and the intrinsic coercivity (H_c) is 367.8 kA m⁻¹. The doped barium hexaferrite powder obtained when x is between 0.3 and 0.4 exhibits high saturation magnetization and a temperature dependence of coercivity close to zero.     

Preparation and magnetic properties of La-Mn and La-Co doped barium hexaferrites prepared via an improved co-precipitation/molten salt method

La-Mn and La-Co doped barium hexaferrites of formula Ba_(1−x)La_xFe_(12−x)M_xO₁₉ (M=Mn, Co) (x=0.05 to 0.40) were prepared with an improved co-precipitation/molten salt method. For the synthesis, aqueous solutions of the appropriate metal chlorides were prepared in the ratio required except that the initial mole ratio of Fe and dopants to Ba was chosen to be 11:1, and then mixed with excess Na₂CO₃. The solutions were then cooled, filtered off, dried, then mixed with KCl flux, and heated at 450 °C and for 2 h. The temperature was then raised to 950 °C and kept for 4 h, then cooled. This new synthesis method, which employs a lower temperature and shorter reaction time, gives products with improved crystallinity and purity while the saturation magnetization and coercivity values are comparable with those synthesized via the high temperature method.     

聚乙二醇辅助下的La-Co-O 复合氧化物合成及其对苯的完全氧化性能研究

以聚乙二醇(PEG)作为分散剂,采用共沉淀法合成La-Co-O复合氧化物,考察添加不同分子量的PEG (0, 2 000, 6 000, 20 000 g·mol-1) 对复合氧化物的物化性质及苯完全氧化性能的影响。采用N₂物理吸附、XRD、SEM、H₂-TPR、O₂-TPD和XPS进行催化剂表征。苯完全氧化反应结果显示催化剂活性顺序为LCO-PEG6000>LCO>LCO-PG20000>LCO-PG2000, LCO-PEG6000催化剂在383 ℃时对苯的转化率达到99%,比LCO低126 ℃。N₂物理吸附实验表明所制备的样品的S_BET均为9～10 m2·g-1。XRD分析显示合成的催化剂均为LaCoO₃钙钛矿主相伴生少量La₂O₃和Co₃O₄杂相,但添加PEG有利于钙钛矿主相的形成。尤其是添加PEG6000有效地抑制了催化剂颗粒的团聚,合成的样品颗粒均匀且尺寸最小。H₂-TPR和O₂-TPD结果表明该催化剂具有更高的还原性能和晶格氧迁移能力,同时XPS分析显示表面活性Co3＋含量最高,这些性质使其具有最高的催化氧化活性。     

甲醇合成二甲醚催化剂的制备与催化性能

采用沉淀法制备CuO-ZnO-Al2O3/ZSM-5和CuO-ZnO-Al2O3-Cr2O3/ZSM-5两种催化剂,用于甲醇脱水制备二甲醚（DME）。用微反-色谱装置对催化剂进行活性评价,用XRD对催化剂进行结构表征。在本实验条件下,以铜锌氧化物的质量分数之比为1∶1,以及铬的质量百分含量为1%,350℃煅烧的催化剂的活性最高。     

Preparation and magnetic properties of barium ferrites substituted with manganese, cobalt, and tin

Barium ferrites substituted by Mn-Sn, Co-Sn, and Mn-Co-Sn with general formulae BaFe_12−2xMn_xSn_xO₁₉ (x=0.2-1.0), BaFe_12−2xCo_xSn_xO₁₉ (x=0.2-0.8), and BaFe_12−2xCo_x/2Mn_x/2Sn_xO₁₉ (x=0.1-0.6), respectively, have been prepared by a previously reported co-precipitation method. The efficiency of the method was refined by lowering the reaction temperature and shortening the required reaction time, due to which crystallinity improved and the value of saturated magnetization increased as well. Low coercivity temperature coefficients, which are adjustable by doping, were achieved by Mn-Sn and Mn-Co-Sn doping. Synthesis efficiency and the effect of doping are discussed taking into account accumulated data concerning the synthesis and crystal structure of ferrites.     

Sonication-Assisted Synthesis of Bimetallic Hg/Pd Alloy Nanoparticles for Catalytic Reduction of Nitrophenol and its Derivatives

In this article, we report a facile approach for the synthesis of an inexpensive catalyst of bimetallic Hg/Pd alloys comprising nanoparticles with various structures using a unique ultrasonic reaction that is conducted without the use of any reducing agent. The nanoparticles of Hg/Pd alloys (HgPd and Hg₂Pd₅) were achieved for the first time by sonicating an aqueous solution of Palladium (II) nitrate with metallic liquid mercury, as evidenced by XRD. EDS further confirmed the presence of Pd and Hg elements in the alloy. The surface morphology and structure of the nanoparticles have been systematically investigated by HRSEM, HRTEM and SAED pattern. In order to explore the catalytic activity of the as-synthesized nanoalloys, the catalytic reduction of 4-nitrophenol and a few other nitrophenol derivatives were investigated. Excellent catalytic activity was obtained for Hg/Pd (1:1) alloy, and the rate constant for the reduction of 4-NP with Hg/Pd at room temperature was found to be 58.4 × 10⁻³ s⁻¹, which is possibly the highest ever reported. The catalyst exhibited superior stability and reusability when compared with those reported in the literature for other catalysts based on noble metals.     

Cu掺杂SnO_2/TiO_2复合薄膜的制备及性能研究

制备Cu掺杂的纳米Sn O2/Ti O2溶胶,采用旋涂法在载玻片上镀膜,经干燥、煅烧制得Cu掺杂的Sn O2/Ti O2薄膜,通过对比实验探讨掺杂比例、条件、复合形式等对结构和性能的影响。采用XRD、SEM、EDS、UVVis等测试手段对样品进行表征,并以甲基橙为探针考察了其光催化降解性能。XRD测试结果显示薄膜的晶型为锐钛矿型,结晶度较高。SEM谱图显示薄膜表面无明显开裂,粒子分布均匀,粒径约为20 nm。EDS测试结果表明薄膜材料中含有Cu元素,谱形一致。UV-Vis吸收光谱表明Cu掺杂以及Sn O2/Ti O2的复合使得在近紫外区的光吸收比纯Ti O2明显增强。光催化实验表明Cu掺杂后使得Sn O2/Ti O2复合薄膜对甲基橙的光催化降解效率进一步提高,Sn O2/Ti O2复合薄膜的光催化活性在10%Cu掺杂时达到最高。     

稀土离子共掺杂的钼酸钙发光材料的合成与光谱性质

采用了化学共沉淀法合成了一系列的镨、铽共掺杂的钼酸钙发光材料,研究了单掺Pr~(3+)和Tb~(3+)以及CaMoO4∶0.03Pr~(3+),yTb~(3+)共掺杂的浓度、温度对材料发光性能的影响。采用X射线衍射仪(XRD)和荧光光谱对样品进行了晶格结构、荧光性质表征。XRD分析表明:样品的主衍射峰与标准卡片(JCPDS 29-0351的衍射峰数据一致,说明少量Pr~(3+)掺杂没有改变基质晶格结构。荧光光谱分析表明,样品在275nm紫外光激发下,发射光谱主要包括多个发射峰,波长为488,560,621和652nm,分别对应于镨离子的~3P_0-~3H_4,~3P_0-~3H_5,~1D_2-~3H_4和~3P_0-~3F_2的跃迁,在掺杂量为3%时,样品特征发射峰最强,CaMoO4∶0.03Pr~(3+)和CaMoO4∶0.05Tb~(3+)的最佳煅烧温度分别为800和600℃。随着Pr~(3+)和Tb~(3+)掺入量的增加,CaMoO4∶Pr~(3+)发光材料的特征发射光谱和激发光谱的特征峰强度逐渐减小,而CaMoO4∶Tb~(3+)材料发光先减小后增大,存在着浓度猝灭效应。此外,在CaMoO4∶0.03Pr~(3+),yTb~(3+)发光体系中,Tb~(3+)的共掺杂可显著增强镨离子的特征发射峰,这是由于存在Tb~(3+)→Pr~(3+)的有效的能量传递。     

Adsorption of 1,2-diaminoethane on ZnO thin films from p-xylene

The interaction of 1,2-diaminoethane (DAE) with ZnO thin films prepared by electrodeposition and magnetron sputtering was investigated by X-ray photoelectron spectroscopy (XPS). The samples were exposed to organic solution of 0.5 M DAE-p-xylene in an Ar atmosphere glove box (O₂ and H₂O <5 ppm), directly connected to the XPS analysis chamber by an anaerobic and anhydrous transfer system. A clear interaction of DAE with the ZnO surface is evidenced by the presence of a high intensity N1s peak at BE = 399.5 ± 0.2 eV and C1s at BE = 286.3 ± 0.2 eV which are attributed to C-N bonding. The atomic ratio C:N was very close to 1:1 consistent with the molecular, non-dissociative adsorption of DAE on the ZnO layer. No significant difference in adsorption of DAE was observed for three different ZnO surfaces despite slight differences in their acid/base properties as evidenced by the O/OH ratio. The results are interpreted in terms of adsorption on Brönsted acid sites. A uniform layer model was used to approximate the DAE film thickness, which was found to be around 10 Å on three studied samples. The N1s and C1s_B signals were observed to decrease on sample exposure to vacuum and/or X-ray irradiation and additional N1s_B peak appeared at lower binding energy at around 398.5 ± 0.2 eV. This is interpreted by the desorption and modification of DAE, indicating low stability of the adsorbed state on ZnO. The exposure to water of the sample with adsorbed DAE causes a significant decrease of the N1s_A and C1s_B peak intensities attributed to the adsorbed DAE molecule, demonstrating the instability of the DAE-ZnO interface in water.