Creating mixed Fe/Al coatings on planar gamma-Al2O3 surfaces

Insufficient understanding of the interactions of reactive phases (e.g., Fe and Al oxides) with minerals, other reactive phases and sorbing species has made predicting and modeling metal sorption on natural sediment surfaces difficult. This work develops a method to create mixed Fe/Al planar oxide surfaces by coating well-characterized planar gamma-Al2O3 with ferric iron. The objective is to closely control the Fe/Al ratio as well as the distribution of Fe on the planar surface. Effects of starting Fe(III) concentration, reaction time and number of coating sequences were examined using XPS and ToF-SIMS. No observable trend was seen in Fe/Al ratios by varying the starting Fe(III) concentration or reaction time. For both 4- and 14-day reactions, lower concentrations of Fe(III) produced oxide phases with a homogeneous distribution of Fe at the surface as detected by ToF-SIMS. ToF-SIMS Fe elemental maps of the oxide phases resulting from the highest Fe(III) concentration showed areas of localized Fe deposition. A sequential coating procedure allowed for a closer control of the concentration and spatial distribution of Fe(III) in the resulting oxide phase. This work provides methodology that can be used to create Fe/Al oxide phases whose Fe/Al content can be controlled for use in subsequent sorption studies to better understand the effects of mixed phase oxides on metal ion uptake.     

Ni/Al2O3和Fe/Al2O3催化剂催化乙醇水蒸气重整制氢的对比研究

甲醇、乙醇等低碳醇催化重整制氢是燃料电池氢源的重要技术之一.乙醇和甲醇相比,更容易存储,低毒且可以从生物质经发酵获得[1,2].乙醇可以通过裂解、部分氧化、水蒸气重整和氧化重整等途径制氢[3~6].已有的文献表明,Pt、Ru、Rh、Pd等贵金属可有效地催化乙醇重整反应,载体多选用     

Prediction of a highly activated state of CO adsorbed on an Al/Fe(100) bimetallic surface

Using periodic slab density functional theory, we investigate CO adsorption, diffusion, and dissociation energetics on a monolayer of Al covering Fe(100) [Al/Fe(100)]. We predict a weakly chemisorbed state of CO to exist on Al/Fe(100), with CO adsorbing on the 4-fold hollow site in a very tilted fashion. This state is predicted to have an extremely low CO stretching frequency of only 883 cm(-1), indicating a dramatically weakened CO bond relative to gaseous CO, even though the molecule is predicted to bind to Al/Fe(100) quite weakly. We predict that dissociation of CO starting from this weakly adsorbed state has a barrier of only approximately 0.35 eV, which is approximately 0.70 eV lower than that on Fe(100). To understand how the underlying substrate changes the electronic properties of the supported Al monolayer, we compare CO adsorption on Al/Fe(100) to its adsorption on analogous pure Al(100) surfaces. This highly activated yet weakly bound state of CO on Al/Fe(100) suggests that Al/Fe(100) could be an effective low-temperature bimetallic catalyst in reducing environments.     

助剂钾对二氧化碳加氢反应活性及产物分布的影响

报导助剂Ｋ对Ａｌ２Ｏ３，ＴｉＯ２，ＺｒＯ２担载Ｆｅ催化剂，用于ＣＯ２加氢合成Ｃ２＋烃的催化活性及产物分布的影响。与不含Ｋ的催化剂相比，Ｋ的存在导致Ｆｅ／Ｋ－Ａｌ２Ｏ３的催化活性及Ｃ＾２＋烃选择性明显提高，但使Ｆｅ／Ｋ－ＴｉＯ２的催化活性及Ｃ２＋烃选择性显著下降，而对Ｆｅ／Ｋ－ＺｒＯ２，这种影响并不显著。Ｋ的明显有利于低碳烯烃的生存。     

Fe-Al layered double hydroxides in bromate reduction: Synthesis and reactivity

This study presents a rare use of layered double hydroxides of Fe(II) and Al(III) (Fe-Al LDH), as reported for the first time for bromate removal from aqueous solutions. The Fe-Al LDH samples were prepared with Fe/Al molar ratios of 1-4 using a co-precipitation method at pH 7, with subsequent hydrothermal treatment at 120°C. The Fe-Al LDH (molar ratio of Fe/Al=1, 2) with a layered structure exhibited nearly complete removal of bromate from initial concentration of 100μmol/dm(3) at a wide pH range of 4.0-10.5 over a 2h reaction period; the residual bromate concentration in the solution was lower than the detection limit of 0.07μmol/dm(3) (9μg-BrO(3)(-)/dm(3)). During the reaction period, bromide was released into the solution via a reduction process. Reactivity of Fe-Al LDH with a Fe/Al molar ratio of 2 did not decrease the bromate reduction efficiency during 30days.     

Phosphorus fractions and phosphate sorption characteristics in relation to the sediment compositions of shallow lakes in the middle and lower reaches of Yangtze River region, China

Phosphorus is recognized as the most critical nutrient limiting lake productivity. The trophic status and development of lake systems are also influenced by the phosphorus content and fractions and phosphate sorption characteristics of the lake sediments. The phosphorus fractions and phosphate sorption characteristics of sediments in shallow lakes from the middle and lower reaches of Yangtze River region in China were investigated. The results show that the phosphorus contents in the sediments ranged from 217.8 to 1640 mg kg(-1); inorganic phosphorus (IP) was the major fraction of total phosphorus (TP); phosphorus bound to Al, Fe, Mn oxides, and hydroxides (Fe/Al-P), and calcium bound phosphorus (Ca-P) were the main fractions of IP. Phosphate sorption on the sediments mainly occurred within 2 h and then reached equilibrium in 10 h. The phosphate sorption rate was closely related to the concentration of fine particles. The phosphate sorption capacity ranged from 128.21 to 833.33 mg kg(-1), showing a significant correlation with the contents of Fe, Fe+Al, total organic carbon (TOC), cationic exchange capacity, total nitrogen, TP, Ca, IP, and the ratio of P/(Al+Fe), and it was higher in the sediments of eutrophic lakes than in mesotrophic lakes. Phosphate was mainly sorbed onto Fe and Al particles. The phosphate sorption efficiency ranged from 26.74 to 312.50 L kg(-1), and had a strong positive correlation with Fe content. For the eutrophic lake sediments, there were no significant relationships between the phosphate sorption efficiency and the selected physical and chemical parameters. But for the mesotrophic lake sediments, the phosphate sorption efficiency was found to be positively related to the contents of Al and Fe+Al.     

Determination of aluminium,copper, iron and manganese in biological and other samples as 8-quinolinol complexes by high-performance liquid chromatography with electrochemical and spectrophotometric detection

A range of methods based on reverse-phase high-performance liquid chromatography is described for determining Al, Cu, Fe and Mn. The simplest method for determining Fe, Cu and Al involves direct formation and separation of the 8-quinolinol complexes on the column, with 1:1 acetonitrile/water containing 5 × 10^?3 M 8-quinolinol, 0.4 M potassium nitrate and 0.02 M acetate buffer (pH 6.0) as the mobile phase, followed by electrochemical detection at ?0.5 V vs. Ag/AgCl and/or spectrophotometric detection at 400 nm. Electrochemical detection enables < 2 ng Cu and < 1 ng Fe to be quantified for injection volumes of 20 μ1. Spectrophotometric detection allows simultaneous determinations of Al, Cu and Fe with lower sensitivity. The method is applied to the determination of Cu, Fe and Al in bovine liver and oyster tissue. Down to 1 ng of manganese (in the 20 μ1 injected) can be determined in biological samples by liquid chromatography with a mobile phase containing 1 mM Tris buffer (pH 8.8) after injection of an externally prepared 8-quinolinol complex. Preconcentration on Sep-Pak cartridges after dichloromethane extraction is used for the determination of low concentrations of iron in water. A sensitive determination of aluminium based on detection at 254 nm is also reported.     

铁系胶体催化剂各组分相互作用的研究

已知催化剂 FeCl3 Al(i Bu)3 Phen(邻菲罗啉 )在加氢汽油介质中对丁二烯聚合有较高的活 性 [1－ 2],作者曾研究了 FeCl3 Al(i Bu)3 Phen体系催化剂的相态,证明该体系为胶体催化剂 [3]. 　　Bushick[4]较早地使用电导率研究烷基铝氯化钛体系离子特性与聚合速率的关系 .至今尚未见从胶体角度研究本体系各组分之间相互作用的报导 . 　　本文是把电导率作为胶体的电学性质之一进行研究的 .主要研究了 FeCl3 Al(i Bu)3 Phen胶体催化剂体系单、多组分溶液的电导率与浓度的关系,结合相应的紫外可见光谱分析结果,…     

All-metal aromatic complexes show high reactivity in the oxidation reaction of methane and some hydrocarbons

The C-H activations of methane, ethane, propane, and propene catalyzed by all-metal aromatic complexes Al(4)Fe were investigated. The results reveal that the rate-determining barrier of methane activation reaction with Al(4)Fe is lower than that of both some well-known inorganic catalysts and some metal organic catalysts. It was found that the all-metal aromatic complexes have high reactivity for the C-H activation of ethane, propane, and propene. Further research showed that the ability of all-metal aromatic complex to accept an electron and the degree of electron delocalization on its aromatic plane had obvious influences on the reactivity of Al(4)Fe. The present work predicts a new kind of catalyst for the alkyl C-H activation reaction: all-metal aromatic catalyst.     

Chemistry and key structural features of oxyhydroxy-fluorides: relationships with the acidic character, thermal stability and surface area

The stability of Al, Cr and Fe hydroxy-fluorides MF_3−x(OH)_x which adopt the hexagonal-tungsten-bronze (HTB)-type structure has been discussed by considering the lability of water coordinated to metals from a kinetic point of view. Thus, in the case of Al or Fe compounds, the easy departure of water contributes to the stabilization of fluoride ions as well as isolated hydroxyl groups around the metal, leading to the formation of the HTB structure. The stabilization of the HTB structure with respect to another structural type, the pyrochlore, with a lower density, is governed by this kinetic feature as well as the ability of fluorinated salts used as precursors to attract hydroxyls. Al(III) and Fe(III) represent the strongest acidic cations and the associated HTB-type structure containing isolated OH groups can easily be stabilized. In the case of Cr, a mixture of pyrochlore and HTB-type structure is generally obtained. We have succeeded in preparing, using supercritical medium, new (Fe, Cr) oxyhydroxy-fluorides which exhibit edge-shared octahedra and large 1D tunnels. These compounds can be considered as potential candidates for acid catalysts.     

Cell membrane electropermeabilization by symmetrical bipolar rectangular pulses. Part II. Reduced electrolytic contamination

The paper presents a comparative study of the contamination of a cell suspension by ions released from aluminum cuvettes (Al(3+)) and stainless steel electrodes (Fe(2+)/Fe(3+)) during cell membrane electropermeabilization by unipolar and by symmetrical bipolar rectangular electric pulses. A single pulse and a train of eight pulses were delivered to electrodes at a 2-mm distance, with 100-micros and 1-ms pulse durations, and amplitudes ranging from 0 to 400 V for unipolar, and from 0 to 280 V for bipolar pulses. We found that the released concentrations of Al(3+) and Fe(2+)/Fe(3+) were always more than one order of magnitude lower with bipolar pulses than with unipolar pulses of the same amplitude and duration. We then investigated the viability of DC-3F cells after 1 h of incubation in the medium containing different concentrations of Al(3+) or Fe(2+)/Fe(3+) within the range of measured released concentrations (up to 2.5 mM for both ions), thus separating the effects of electrolytic contamination from the effects of electropermeabilization itself. For Fe(2+)/Fe(3+), loss of cell viability became significant at concentrations above 1.5 mM, while for Al(3+), no effect on cell survival was detected within the investigated range. Still, reports on the biochemical effects of released Al(3+) also suggest that with aluminum cuvettes, electrolytic contamination can be detrimental. Our study shows that electrolytic contamination and its detrimental effects can be largely reduced with no loss in efficiency of electropermeabilization, if bipolar rectangular pulses of the same amplitude and duration are used instead of the commonly applied unipolar pulses.     

Elemental analysis in cultured cells, tobacco and grape, treated with aluminum

We discussed the relationship between Al toxicity and the Al, Fe andB amount of element in tobacco and grape cells. Al and Fe were analyzed byneutron activation analysis and B was analyzed by prompt gamma-ray analysis.Callose content was also measured as an indicator of cell damage induced Altoxicity. When tobacco cells were incubated in 1 mM and 300 µM Al solution,the pattern of callose formation was much similar to that of Fe accumulationthan that of Al accumulation in tobacco cells, suggesting that the increaseof Fe content induced toxic effect along with Al incorporated into the cells.However, this tendency was not observed in grape cells. Boron content didnot show any relation to those of Al or Fe throughout the Al treatment inboth tobacco and grape cells.     

铝的毒性作用对铁、钙和镁生理功能的影响及相关机理的研究概况

本文综述了近年来铝的毒性作用对铁、钙和镁生理功能的影响及相关机理的研究概况.并讨论了铝在阿尔茨海默氏病(Alzhmers disease, AD),帕金森氏病(Parkinson's disease, PD)及透析病中毒性作用机理.引用文献50篇.     

电感耦合等离子体原子发射光谱法同时测定石灰石中铁、铝、钙、镁、硅

采用碱熔法,以移液枪分取试样,用电感耦合等离子体原子发射光谱法同时分析石灰石中铁、铝、钙、镁、硅5种化学成分。在分析过程中对氩气加湿,避免盐析效应的影响,铁、铝、钙、镁、硅的分析谱线分别为259.940,396.152,315.887,279.553,251.611 nm。5种成分在各自的线性范围内均具有良好的线性,线性相关系数在0.990 74~0.999 99之间,方法检出限为0.000 6%~0.005 1%,回收率为95.6%~105.4%,测定结果的相对标准偏差小于1%(n=6)。该方法检出限低、重现性好,适合于石灰石样品中铁、铝、钙、镁、硅的快速检测。     

Spectral interference on the emission of sulphur I 180.73 nm in an inductively coupled plasma

Spectral interferences on the S I 180.73 nm emission line by Al, Ca, Mn and Fe in an inductively coupled plasma are described. The critical concentration ratios for Ca, Mn, Al and Fe with respect to S are 90, 300, 3300 and 25000 respectively (full width at half maximum = 0.0075 nm). Intensity measurements at various observation zones in the plasma show that the spectral interference from Ca and Mn emission line overlaps may be reduced by observing the S emission at a lower observation height in the plasma.     

Studies on the Synthesis and the Structure of Ferric Aluminum Magnesium Hydrotalcite—like Compounds

Hydrotalcite-like compounds (HTlc) are composed of trivalent and divalent metal ions, the general formula 1 is: [M2+1-xM3+x(OH)2]x+An-x/n·mH2O M3+ is trivalent metal ions, M2+is divalent metal ions, A is negative ions whose valence is n, and m is the amount of water in the crystal, and x is the molar ratio of trivalent metal ions to all metal ions. A lot of studies have been done on the synthesis and property of HTlc, which is made up of two kinds of the metal ions. It has been found …     

A systematic approach to optimum working conditions with inductively coupled plasma atomic emission spectrometry

Optimum experimental factors were determined for the analytical determination of Al, Cd, Fe, Pb, and Zn by ICP atomic emission spectrometry. Based on systematically determined factor levels, working conditions were found that gave similiar, and sometimes better results compared with the hitherto used levels of factors. All measurements were performed with a sampling time of 150 ms as often used in routine analysis in the laboratory. This optimization resulted in a reduced outer plasma gas flow from 15 L/min argon to 12 L/min without any relevant changes of the achievable detection limits. A serious problem was that only one analytical line of Al could be used. A comparison with the lower limit of application (comparable with the detection limit) from German directive DIN 38406, part 22 ([1]), showed that the detection limits of Al and Fe are superior, whereas for Cd there was only little improvement. The detection limits of Zn and especially Pb are always higher than the lower range of application under these conditions. Therefore, the use of two device-parameter sets for hard and soft lines, respectively, is strongly suggested. Maps with the observed signal-to-noise-ratios were systematically acquired for each element analyzed in connection with different strategies for optimum search.     

表面形貌控制增强铁基载氧体与褐煤化学链燃烧反应活性

为探究载氧体形貌控制获取适用于化学链燃烧的高活性表面结构载氧体的可行性,以Fe2O3作为模型载氧体,从理论上对比研究Fe2O3的高弥勒指数晶面(104)和Fe2O3自然裸露的最主要晶面之一(001)的表面电子特性,结果表明,Fe2O3(104)的电子结构更有利于表面与煤模型分子的相互作用.基于理论分析结果,从实验上控制制备了单晶载氧体Fe2O3(104)/Al2O3,研究了该载氧体与褐煤的化学链燃烧反应特性.Fe2O3(104)/Al2O3比传统浸渍法制备的载氧体Fe2O3/Al2O3具有更高的反应活性,与理论计算结果一致.元素分析表明,Fe2O3(104)/Al2O3与褐煤反应的积碳量远少于Fe2O3/Al2O3与褐煤反应的积碳量.对比新鲜载氧体及再生后载氧体的结构发现,Fe2O3(104)/Al2O3在反应过程中不断进行氧化还原反应而发生结构弛豫后,仍然能通过氧化再生.这表明形貌控制制备可为化学链燃烧技术开发新型高效载氧体提供新思路.     

Fe_(6-x)Al_x团簇的结构和磁性能

在密度泛函理论的BPW91水平上,对Fe6-xAlx团簇进行了结构优化,并将获得的最低能结构进行稳定性分析以及电子结构和磁性能的计算.计算结果表明,铁原子倾向团聚在一起并占据最高配位,Al原子则倾向分布在铁簇的周围尽最大可能地与Fe配位成键.Fe6-xAlx团簇的磁性随Al原子数目增加呈现下降趋势,自然轨道分析揭示Fe4s和Al3s与Fe3d之间的杂化是导致团簇磁矩下降的主要原因.     

Fe-Mn/Al2O3催化剂低温 NH3选择性催化还原 NO的性能

本文制备了一系列 Fe-Mn/Al2O3催化剂,并在固定床上考察了其 NH3低温选择性催化还原 NO的性能.首先考察了不同 Fe负载量制备的催化剂的脱硝性能,优选出最佳的 Fe负载量;在此基础上,研究了 Mn负载量对催化剂脱硝效率的影响;最后,对优选催化剂的抗 H2O和抗 SO2性能进行了实验研究;同时,对催化剂由于 SO2所造成的失活机制进行了考察.采用 N2吸附-脱附、X射线衍射、透射电镜、能量弥散 X射线谱、程序升温还原、程序升温脱附、X射线光电子能谱、热重和傅里叶变换红外光谱等方法对催化剂进行了表征.结果表明,最佳的 Fe和 Mn负载量均为8%,所制的8Fe-8Mn/Al2O3催化剂在150°C的脱硝效率可达近99%;同时,在整个低温测试区间(90–210°C)的脱硝效率均超过了92.6%. Fe在催化剂表面主要以 Fe3+形态存在,而 Mn主要包括 Mn4+和 Mn3+; Mn的添加提高了 Fe在催化剂表面的积累,促进了催化剂比表面积增大和活性物种分散,改善了催化剂氧化还原性能和对 NH3的吸附能力.催化剂的高活性主要是由于其具有较大的比表面积、高度分散的活性物种、增加的还原特性和表面酸性、较低的结合能、较高的 Mn4+/Mn3+和增强的表面吸附氧.此外,8Fe-8Mn/Al2O3的催化性能受 H2O和 SO2影响较小,抗 H2O和 SO2能力较强.同时,反应温度对催化剂的抗硫性有重要影响,在较低的反应温度下,催化剂抗硫性更好; SO2造成催化剂活性降低主要是由于催化剂表面硫酸盐物种的生成.一方面,表面硫酸铵盐的生成造成催化剂孔道堵塞和比表面积降低,减少了反应中的气固接触从而导致活性降低;另一方面,催化剂表面的活性物种被硫酸化,造成反应中的有效活性位减少,从而降低了催化剂活性.