Preparation and Characterization of Mesoporous Ce0.5Zr0.5O2 Mixed Oxide

Mesoporous （MSU） Ce0.5Zr0.5O2 mixed oxide with a high specific surface area has been synthesized under weak acidic condition in the presence of an anionic surfactant, sodium dodecylbenzenesulfonate. The effect of the pH value on the formation of mesostructure and the thermal stability of the material has been evaluated. The products were characterized by transmission electron microscopy, powder X-ray diffraction and nitrogen adsorption-desorption measurements. The results showed that the as-prepared Ce0.5Zr0.5O2 mixed oxide possessed a specific surface area of 163.3 m^2·g^-1, which had a cubic fluorite-type structure and possessed specific surface areas of 148.4 and 62.4 m^2·g^-1 after calcination at 500 and 800 ℃ for 2 h, respectively. The material showed excellent thermal stability.     

Autothermal Reforming of Methane over Ni Catalysts Supported on CuO-ZrO2-CeO2-Al2O3

Ni catalysts supported on various mixed oxides of Al2O3 with rare earth oxide and transitional metal oxides were synthesized. The studies focused on the measurement of the autothermal reforming of methane to hydrogen over Ni catalysts supported on the mixed oxide ZrxCe30-xAl70Oδ (x=5, 10, 15). The catalytic performance of Ni/Zr10Ce20Al70Oδ was better than that of other catalysts. XRD results showed that the addition of Zr to Ni/Ce30Al70Oδ prevented the formation of NiAl2O4 and facilitated the dispersion of NiO. Effects of CuO addition to Zr10Ce20Al70Oδ were also investigated. The activity of Ni catalyst supported on CuO-ZrO2-CeO2-Al2O3 was somewhat affected and the Ni/Cu5Zr10Ce20Al65Oδ showed the best catalytic performance with the highest CH4 conversion, yield of H2, selectivity for H2 and H2/CO production ratio in operation temperatures ranging from 650 to 750℃.     

Double perovskite oxides Sr_2Mg_(1-x)Fe_xMoO(6-δ) for catalytic oxidation of methane

The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible(Fe2+,Mo6+) and (Fe3+,Mo5+)valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.     

Low Temperature Catalytic Combustion of Ethanol over Pt/γ-Al_2O_3/Ce_xZr_(1-x)O_2 Honeycomb Catalysts

It has been found that the catalytic activity toward the decomposition of ethanol in a fix bed reactor can be greatly improved by loading Pt on the surface of CexZr1-xO2. In this study, we have investigated the effects of different x of Pt/γ-Al2O3/CexZr1-xO2 on the catalytic activity of catalysts. The prepared catalysts were characterized by BET, XRD, and TPR. The BET surface areas of the catalysts decreased with x decreasing. XRD results reveal that deposited Pt dispersed on the CexZr1-xO2 and γ-Al2O3 matrix. The order of catalytic activities is Pt/y-Al2O3/Ce0.5Zr0.5O2＞Pt/γ-Al2O3/Ce0.25Zr0.75O2＞Pt/γ-Al2O2/Ce0.75Zr0.25O2＞Pt/y-Al2O3/CeO2＞Pt/γ-Al2O3/ZrO2. Among the catalysts, the reduction peak area of Pt/γ-Al2O3/Ce0.5Zr0.5O2 is the largest and the oxygen mobility is noticeably pro-moted, which is in good harmony with the catalytic activity. Incorporation of ZrO2 into the CeO2 lattice considerably decreases the destruction temperature for ethanol. Based on these observations, the mechanistic role of oxygen mo-bility in the oxidation reaction has been suggested.     

Preparation and Photocatalytic Properties of Ti1-xZrxO2 Solid Solution

A series of Ti1-xZrxO2 materials were synthesized through a multistep sol-gel process. The structural characteristics were investigated using X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and Raman measurements. The experimental results showed that a solid solution could be obtained at low Zr/（Ti＋Zr） molar ratios （x ≤0.319）. Raman measurements exhibited that the presence of zirconium in the solid solutions greatly retarded the amorphous-anatase and anatase-rutile transitions. The diffuse reflectance UV-Vis spectra revealed that the bandgap of the solid solution was enlarged gradually with the increment of incorporated zirconium content. The Ti1-xZrxO2 solid solutions exhibited higher photocatalytic activity than pure TiO2 for the degradation of 4-chlorophenol aqueous solution.     

溶胶-凝胶新方法合成介孔铁酸铜纳米粉体催化剂上CO低温氧化(英文)

Mesoporous CuFe2O4 solid solution nanopowders with high specific surface areas were synthesized by a novel, very simple and inexpensive sol-gel route using propylene oxide as gelation agent, and used as the catalyst in low temperature CO oxidation. The samples were characterized by X-ray diffraction, N2 adsorption-desorption, thermogravimetric/differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and temperature-programmed reduction. The results revealed that the samples have a nanocrystalline structure with crystals in the range of 10 to 25 nm, and that all the catalysts have mesoporous pores. The addition of Cu into iron oxide affected its structural and catalytic properties. The sample containing 15 mol% Cu showed the highest specific surface area and catalytic activity, and showed high catalytic stability in low temperature CO oxidation.     

Selective catalytic oxidation of NO with O2 over Ce-doped MnOx/TiO2 catalysts

A series of Ce-doped MnOx/TiO2 catalysts were prepared by impregnation method and used for catalytic oxidation of NO in the presence of excess O2. The sample with the Ce doping concentration of Ce/Mn=1/3 and calcined at 300°C shows a superior activity for NO oxidation to NO2. On Ce(1)Mn(3)Ti catalyst, 58% NO conversion was obtained at 200°C and 85% NO conversion at 250°C with a GHSV of 41000 h-1, which was much higher than that over MnOx/TiO2 catalyst (48% at 250°C). Characterization results implied that the higher activity of Ce(1)Mn(3)Ti could be attributed to the enrichment of well-dispersed MnOx on the surface and the abundance of Mn3+ and Ti3+ species. The addition of Ce into MnOx/TiO2 could improve oxygen storage capacity and facilitate oxygen mobility of the catalyst as shown by PL and ESR, so that its activity for NO oxidation could be enhanced. The effect of H2O and SO2 on the catalyst activity was also investigated.     

Effect of pretreatment methods on the performance of Cu-Zr-Ce-O catalyst for CO selective oxidation

The Cu-Zr-Ce-O catalysts prepared using the coprecipitation method exhibited better catalytic performance for CO selective oxidation. The Cu-Zr-Ce-O catalysts pretreated with different methods were studied by CO-TPR and XPS techniques. The results showed that the Cu-Zr-Ce-O catalyst pretreated with oxygen exhibited the best catalytic performance and had the widest operating temperature window, with CO conversion above 99% from 160 to 200 ℃. The O2 pretreatment caused an enrichment of the oxygen storaged on the Cu active species and promoted the conversion of adsorbed oxygen into surface lattice oxygen. It also improved the amount of Cu＋/Cu^2＋ ionic pair, and then facilitated the formation of CuO active species on the catalyst for selective CO oxidation.     

纳米 Ce1MgxZr1-xO2 固体多相催化剂的制备、表征及催化合成四氢苯并[b]吡喃衍生物的性能

 A series of Ce1MgxZr1-xO2 mixed metal oxides with different molar ratios were prepared by simple co-precipitation and were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, temperature-pro- grammed desorption of CO2, and N2 adsorption techniques. The prepared materials were tested for catalytic activity by the synthesis of tet-rahydrobenzo[b]pyran derivatives using a three component reaction (aromatic aldehydes, malononitrile, and dimedone) in an ethanol me-dium. The best catalytic activity was obtained with Ce1Mg0.6Zr0.4O2. The particle size or crystallite size was estimated using the De-bye-Scherrer equation. The addition of magnesium oxide into the ceria-zirconia lattice resulted in the formation of nanosized particles rang-ing from 5.41 to 9.78 nm. This work describes the catalytic behavior of magnesium oxide in mixed metal oxide systems.     

Promotional effect of cerium on nickel-containing mesoporous silica for carbon dioxide reforming of methane

A series of Ce-promoted 6.7%Ni-containing mesoporous silica(Ce-Ni-Si O2)with varying Ce content(0.5%–4.8%)was prepared using the evaporation-induced self-assembly method.The characterization results showed that Ce and Ni species were homogeneously incorporated into the mesoporous silica matrix.The catalytic properties of these samples in the dry reforming of methane reaction revealed that the catalysts(e.g.,1.2%Ce-Ni-Si O2)containing highly dispersed small Ni particles exhibited excellent catalytic activity and long-term stability,which is attributed to the anchoring effect of the Ce and its ability to increase surface oxygen species concentration.     

Ag负载TiO2纳米管微波辅助水热法制备及其光催化性能

以微波辅助水热法制备了二氧化钛纳米管,然后通过浸渍法在其表面负载了银纳米颗粒.所得样品用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、氮吸附、X射线光电子能谱(XPS)、紫外-可见漫反射等测试方法表征.微波加热处理可以大大缩短反应时间,产物为无定型纳米管,经高温焙烧后转变成锐钛矿型二氧化钛.所得纳米管的外径为7-8 nm,内径为5-6 nm,管长约200 nm,比表面积可达371 m2·g-1.负载的银分散在纳米管的表面,对纳米管的结构与晶型没有影响,但是拓宽了二氧化钛的光吸收范围,使吸收边红移至可见光区,并且有效抑制了光生电子空穴的复合.在可见光降解罗丹明B的实验过程中,与Ag负载的P25及纯二氧化钛纳米管相比,Ag负载二氧化钛纳米管具有更高的可见光催化活性,并且当Ag/Ti 物质的量的比为0.5%时,可见光催化性能最好.     

Thermodynamic investigation of the redox properties for ceria-hafnia, ceria-terbia, and ceria-praseodymia solid solutions

Ceria-hafnia, ceria-terbia, and ceria-praseodymia solid solutions were prepared by the citric-acid (Pechini) method and characterized using X-ray diffraction (XRD) for structure and coulometric titration for redox thermodynamics. Following calcination at 973 K, XRD showed that both Ce(0.5)Hf(0.5)O2 and Ce(0.8)Hf(0.2)O2 exist as single-phase solid solutions and that the lattice parameters of the cubic fluorite structures shifted linearly with Hf content. Following calcination at 1323 K, Ce(0.8)Hf(0.2)O2 remained single phase but Ce(0.5)Hf(0.5)O2 separated into two phases with compositions of Ce(0.81)Hf(0.19)O2 and Ce(0.15)Hf(0.85)O2. At 973 K, oxidation isotherms for Ce(0.8)Hf(0.2)O2 and Ce(0.5)Hf(0.5)O2 were almost identical to oxidation isotherms for Ce(0.8)Zr(0.2)O2 and Ce(0.5)Zr(0.5)O2. Mixed oxides of ceria with terbia and praseodymia also formed single-phase fluorite structures, but each of the solid solutions was phase stable to calcination at 1323 K. The oxidation isotherms for the solid ceria-terbia and ceria-praseodymia solutions were similar to what would be expected for physical mixtures of these oxides.     

S、Al掺杂TiO2纳米材料的固相合成及其可见光降解性能

采用固相反应法分别合成了硫掺杂二氧化钛(S-TiO2)、铝掺杂二氧化钛(Al-TiO2)及硫和铝共掺杂二氧化钛(S-Al-TiO2)纳米材料,并对材料进行了XRD、SEM、UV-Vis、XPS、Raman、N2吸附-脱附等物相织构表征,同时研究了材料对溴甲酚绿(BCG)的可见光降解活性。结果表明,在S-Al-TiO2纳米材料中,硫以阳离子S6+进入二氧化钛晶格,铝以同晶取代方式占据TiO2晶格中Ti的位置,其晶型为锐钛矿型。S、Al共掺杂能有效地抑制TiO2晶粒的生长,其紫外-可见漫反射吸收光谱涵盖了可见光区并延伸到近红外区域。材料的光催化活性决定于掺杂元素及其掺杂量。在25℃、pH=6.5下,S-Al-TiO2纳米材料对溴甲酚绿的可见光降解具有很高的活性,并服从一级反应动力学规律。当S与Al投料物质的量的比为1∶9时,S-Al-TiO2(1S-9Al)纳米材料对BCG的可见光降解速率常数为0.03286 min-1,分别是纯TiO2、S-TiO2及Al-TiO2的5.46、2.62和4.63倍。50 min内,S-Al-TiO2(1S-9Al)纳米材料对BCG的可见光降解率达80%。     

钴掺杂二氧化钛的光催化制氢性能

采用聚合络合法（PCM）制备出钴掺杂二氧化钛（CO/TiO₂）光催化剂.以热重-差示扫描量热同步热分析（TGA-DSC）,傅里叶变换红外（FT-IR）光谱,X射线粉末衍射（XRD）,氮气吸附-脱附,紫外-可见漫反射光谱（UV-Vis DRS）,X射线光电子能谱（XPS）等手段对材料进行了表征.采用光催化制氧作为探针反应,以氧气的产量评价材料的光催化性能结果表明:采用聚合络合法制备的样品主体成分为锐钛矿晶型的二氧化钛,钴元素呈高度分散,钴的掺杂能够明显提升二氧化钛光催化材料的光催化制氢活性,当钴钛物质的量之比为0.3%时,催化剂具有最佳的光催化制氢活性,达到2499μmol,是同等条件下制备的无掺杂二氧化钛的近六倍.还对钴离子掺杂增强机理进行了探讨.     

ZnO/CdS复合材料的合成与可见光催化性能

采用喷雾辅助气相沉积法在水热法合成的ZnO纳米线上沉积CdS纳米颗粒。采用X射线衍射仪（XRD）、激光拉曼仪（Raman）、扫描电镜（SEM）、透射电镜（TEM）、X射线光电子能谱分析谱（XPS）和紫外可见漫反射光谱等测试手段对复合光催化剂进行表征。结果表明,3~10 nm的CdS纳米粒子修饰在直径约为100 nm ZnO纳米线的表面。XPS和Raman表明复合材料中ZnO和CdS之间存在化学相互作用。可见光催化降解罗丹明B实验结果表明ZnO/CdS复合材料的催化性能优于单相CdS或ZnO,沉积时间为30 s合成的ZnO/CdS速率常数分别是CdS和ZnO的2.91和4.03倍,且具有较高的稳定性。ZnO/CdS复合材料光催化性能增强的可能原因为光吸收范围的拓展和光生载流子分离效率的提高。     

A novel chelating acid-assisted thermolysis procedure for preparation of tin oxide nanoparticles

Pure tin dioxide (SnO₂) nanoparticles were synthesized via thermolysis of tin phthalate and tin oxalate in the presence of oleic acid (OA) as solvent. Oleic acid (OA) was employed as an organic solvent, which can be applied to control particle growth and to stabilize the particles. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The orthorhombic phase SnO₂ nanoparticles with average size about 12 nm were synthesized through thermolysis of tin phthalate in the presence of oleic acid.     

Synthesis of cubic Ag@AgCl and Ag@AgBr plasmonic photocatalysts and comparison of their photocatalytic activity for degradation of methyl orange and 2,4-dichlorophenol

Uniform cubic Ag@AgCl and Ag@AgBr plasmonic photocatalysts with side length of 0.7 µm were synthesized by a facile green route, in which a controllable double-jet precipitation technique was employed to fabricate homogeneous cubic AgCl and AgBr grains while a photoreduction process was used to produce Ag nanoparticles (NPs) on the surface of AgCl and AgBr grains. The synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS). The photocatalytic activities of Ag@AgCl and Ag@AgBr were compared using degradation of methyl orange (MO) dye and 2,4-dichlorophenol (2,4-DCP) under visible-light irradiation. Ag@AgBr showed higher photocatalytic activity for MO degradation but weaker activity for 2,4-DCP decomposition. Possible degradation mechanisms are proposed to interpret these contrary paradoxical experimental results.     

六方硼碳氮化合物的溶剂热合成与表征

采用溶剂热合成方法,以无水乙腈、叠氮化钠和四氟硼酸钠为原料,以苯为溶剂,在温度为400℃条件下,成功合成出了硼碳氮(BCN)三元化合物.利用X射线粉末衍射(XRD)、Fourier变换红外光谱(FTIR)、透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线能谱(EDS)和电子能量损失谱(EELS)对合成产物进行了表征.XRD和SAED分析表明,合成产物为六方相,晶格常数为a=0.2678nm,c=0.6639nm;TEM结果表明,合成产物中存在纳米棒和四方柱状块体BCN;EELS和EDS分析表明,产物由B,C,N三种元素组成,化学式为B0.23C0.60N0.17;FTIR分析表明样品中存在C—N,B—C和B—N键,表明B,C,N三元素之间达到了原子级化合.     

微波固相法快速制备氮掺杂石墨烯

以鳞片石墨为原料,首先通过Hummers法制备氧化石墨,再将洗涤至中性的氧化石墨分散液与乙二胺反应得到功能化石墨烯。干燥后的功能化石墨烯在微波辐照下能瞬间产生高热,促使接枝的乙二胺分子分解并实现对石墨烯原位掺杂制备出氮掺杂石墨烯。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、X射线衍射(XRD)、X射线能谱(EDS)对样品的形貌、结构和组成进行了表征。结果表明:该合成途径能成功实现对氧化石墨烯的还原和掺杂,所合成的氮掺杂石墨烯呈现透明绢丝状结构。     

微波固相法快速制备氮掺杂石墨烯

以鳞片石墨为原料, 首先通过Hummers法制备氧化石墨, 再将洗涤至中性的氧化石墨分散液与乙二胺反应得到功能化石墨烯。干燥后的功能化石墨烯在微波辐照下能瞬间产生高热, 促使接枝的乙二胺分子分解并实现对石墨烯原位掺杂制备出氮掺杂石墨烯。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、X射线衍射(XRD)、X射线能谱(EDS)对样品的形貌、结构和组成进行了表征。结果表明:该合成途径能成功实现对氧化石墨烯的还原和掺杂, 所合成的氮掺杂石墨烯呈现透明绢丝状结构。