Academic literature on the topic 'Electron-catalytic method'

Applications of transition metal sulfides for hydroprocessing catalysts have included a variety of reactions. It is generally believed that an interaction between the active phase (Mo or W) and the promoter (Co or Ni) takes place. Several models have been suggested to explain the enhanced catalytic activity. The catalytic properties of the unsupported sulfides are dependent on the catalyst preparation methods . In this work we study by electron microscopy two sets of unsupported samples ranging from molybdenum sulfide to cobalt sulfide. The specimens were prepared by the following methods, a slight variation of the classical homogeneous sulfide precipitation (HSP) method, and a new method called impregnated thiosalt decomposition (ITD).

AbstractIn this study, nitrocellulose (NC) fiber blanket prepared by electrostatic spinning method has been used as a template, and copper nitrate (Cu(NO3)2) as an oxidant to synthesise polyaniline nanotubes doped with heteropolyacid (H4SiW12O40, SiW12) using UV light catalytic method. Infrared spectroscopy (IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technologies were applied to characterize the prepared samples of polyaniline nanotubes. The results show that the external diameter of the tube is about 200 nm, and the internal diameter about 170 nm. We also give a reasonable speculation and explanation about the formation mechanism of the nanotubes.

Ag nano deposited on TiO2 (Degussa P25) (Ag nano/TiO2) photo-catalyst has been synthesized by g-irradiation method. The characteristics of Ag nano/TiO2 material has been investigated by BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM) and the diffuse reflectance spectra (DRS). The photo-catalytic properties of Ag nano/TiO2 for degradation of Rhodamine B in aqueous solution under visible light have been studied. Results indicated that Ag nano/TiO2 photo-catalyst exhibited better photo-catalytic activity compared to that of TiO2 under the same reaction condition. The higher activity of Ag nano/TiO2 is due the enhancement of electron–hole separation effect on the surface of the catalyst. At 1.5% Ag doping content, the Ag nano/ TiO2 photo-catalyst exhibited the highest photo-catalytic activity under visible light.

Porous LaFeO3 were synthesised by nanocasting method using mesoporous silica (SBA-15) as a hard template and used as a visible-light-driven photocatalyst. The as-synthesised LaFeO3 photocatalyst were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray Diffraction (XRD), N2 adsorption-desorption, and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-vis DRS). The photo-Fenton catalytic activities of porous LaFeO3 were investigated for the degradation of oily-containing wastewater. The results showed that porous LaFeO3 had better photo-Fenton catalytic activity under visilbe light irradiation than pure LaFeO3. The remarkable improvement photo-Fenton catalytic activity of porous LaFeO3 material could be attributed to the synergistic effect of adsorption and visible light photo-Fenton processes thanks to its porous structure.

ZrO2nanotube arrays were prepared by anodization method in aqueous electrolyte containing (NH4)2SO4and NH4F. The morphology and structure of nanotube arrays were characterized through scanning electron microscope, X-ray diffraction, and infrared spectra analysis. The zirconia nanotube arrays were used as catalyst in esterification reaction. The effects of calcination temperature and electrolyte concentration on catalytic esterification activity have been investigated in detail. Experiments indicate that nanotube arrays have highest catalytic activity when the concentration of (NH4)2SO4is 1 mol/L, the concentration of NH4F is 1 wt%, and the calcination temperature is 400°C. Esterification reaction yield of as much as 97% could be obtained under optimal conditions.

Abstract FeNiCeOx was firstly prepared by ultrasonic impregnation method and used to remove diclofenac in a Fenton-like system. The catalytic activity was improved successfully by doping Ni into FeCeOx. The diclofenac removal efficiency reached 97.9% after 30 min reaction. The surface morphology and properties of FeNiCeOx were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Raman and X-ray photoelectron spectroscopy (XPS) analyses. FeNiCeOx in this paper had larger specific surface area than those prepared by other methods, which was attributed to the cavitation effect and hot-spot effect during the ultrasonic synthesis process. Low crystallinity of Fe2O3 and NiO showed by characterization could lead to high interaction of Fe and Ni ions with support of CeO2. They substituted Ce in CeO2, caused lattice contraction and formed more oxygen vacancies, which favoured the catalytic reaction. Meanwhile, Fe and Ce ions both had redox cycles of Fe3+/Fe2+ and Ce4+/Ce3+, which facilitated the electron transfer in the reaction. The synergistic effect among Fe, Ni and Ce might lead to better catalytic performance of FeNiCeOx than any binary metal oxides constituted from the above three elements. Finally, the potential mechanism of diclofenac removal in FeNiCeOx-H2O2 system is proposed.

Ag nano-particles were deposited on the surface of TiO2 self-assembled films by photo-reduction of Ag+ solution. SPM, XPS and UV-Vis spectrophotometer were employed to characterize the microstructure and photo-catalytic performance of the films. An obvious enhancement of photo-catalytic activity had been observed. Since rutile had a lower optical band gap than anatase, a higher photo-catalytic efficiency improvement of rutile than that of anatase was obtained under the help of Ag nano-particles, which acted as electron acceptors.

A simple method was applied to fabricate phase-pure hollow CuS microspheres. The obtained product was characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectra and UV-Vis absorption spectroscopy. Further, the catalytic activity of CuS spheres was evaluated by the decolorization of Rhodamine B in the presence of hydrogen peroxide solution at room temperature. The results indicated that the product showed a good optical propertie, and the hollow sphere CuS could be an effective catalytic material.

The catalytic combustion technique was used to synthesize carbon nanotubes and carbon nanofibers. In this paper, we report that carbon nanofibers were synthesized by ethanol catalytic combustion technique. The as-grown products were characterized by means of scanning electron microscopy, transmission electron microscopy, Raman spectroscopy. The results showed that the products have a mass of carbon nanofibers. However, morphology and microstructure of carbon nanofibers are affected by synthesis conditions, such as stability of flames and sampling time, sampling temperature etc. Different Influence factors were depicted in detail. Ethanol catalytic combustion technique offer a simple method to synthesize carbon nanotubes and carbon nanofibers, it also has some advantages, such as flexible synthesis conditions, simple setup, and environment-friendly.

A method to prepare monodispersed silica nanospheres as templates for fabrication of nickel-silica composite hollow spheres is presented. The structures for both silica nanospheres and nickel-silica composite hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The catalytic activity for acetone hydrogenation on nickel-silica composite hollow spheres was evaluated, and high conversion efficiency of 70% with good selectivity of 82.7% to 2-propanol was observed. The mechanism of high catalytic activity and good selectivity in acetone hydrogenation reaction was discussed.

Робота виконана на кафедрі хімічних технологій та водоочищення Черкаського державного технологічного університету Міністерства освіти і науки України.
Дисертація присвячена питанням розробки технологій інтенсифікації первинних ендотермічних стадій реакцій горіння та окиснення сировини, що містять вуглеводневі гази і тверді вуглеводні, які базуються на використанні направленої дії штучно створеної низькотемпературної плазми з упорядкованим рухом «повільних» електронів в присутності гетерогенного каталізатору та визначення оптимальних умов проведення цих процесів. Розроблений новий напрям в проведенні окиснювальних процесів, який базується на використанні для інтенсифікації первинних ендотермічних стадій реакцій горіння та окиснення сировини, що містить вуглеводневі гази і тверді вуглеводні, низькотемпературної плазми з упорядкованим рухом «повільних» електронів в присутності гетерогенного каталізатору. Штучно створена низькотемпературна нерівноважна плазма, при її короткотривалій дії на об’єкт горіння або окиснення, дає можливість проводити хімічні реакції, які в звичайних умовах можливі при значних енерговитратах або не протікають, або протікають дуже повільно. Мінімізація енерговитрат в процесах, що пропонуються, досягається з використанням каталізу в зоні розряду. Для створення низькотемпературної плазми запропоновано використання бар′єрного та об′ємного розрядів. Цей напрям отримав назву електронно-каталітичний метод. Використання цього методу в процесах горіння і окиснення дозволяє витрачати на процес інтенсифікації ендотермічних стадій значно меншу кількість енергії завдяки використанню енергії «повільних» електронна, на утворення яких впливає нерівноважна плазма. При горінні паливної суміші в предполумьяній зоні значно зменшується вміст води, на руйнування якої витрачалося велика кількість енергії. Замість неї утворюються радикали і іони, теплоємність яких значно менше теплоємності води і завжди має негативне значення. Енергія, яка витрачалася на руйнування, додається до сумарної енергії, що надають електрони і протони. Сумарний енергетичний внесок всіх утворюються при з'єднань, достатній, щоб ініціювати як процес горіння, так і окислення різних з'єднань. Для газової фази досягався додатковий енергетичний ефект в розмірі 12-15% від кількості енергії, що виділяється при звичайному згорянні палива.
Dissertation is devoted to the development of technologies for the intensification of endothermic stages of combustion and oxidation reactions on hydrocarbon gases and solid hydrocarbons based on the directional action of artificially created low-temperature plasmas with the ordered motion of "slow" electrons in the presence of a heterogeneous catalyst and determining the optimum conditions for carrying out these processes. A new direction has been developed in carrying out oxidation processes, which are based on the use of a low-temperature plasma with the ordered motion of "slow" electrons in the presence of a heterogeneous catalyst for the intensification of the endothermic stages of combustion and oxidation reactions on hydrocarbon gases and solid hydrocarbons. An artificially created low-temperature nonequilibrium plasma, with its short-term action on the object of combustion or oxidation, makes it possible to conduct a chemical reaction, which under normal conditions is possible at considerable energy costs, or proceed very slowly. Minimization of energy consumption in the proposed processes is achieved by using catalysis in the discharge zone. To create a low-temperature plasma, it is proposed to use a barrier and volume discharge. This direction was called the electron-catalytic method. The use of this method in combustion and oxidation processes allows a much smaller amount of energy to be expended on the process of intensification of endothermic stages due to the use of the energy of "slow" elecrons, the formation of which is affected by the nonequilibrium plasma. When the fuel mixture burns in the presumed zone, the water content significantly decreases, and a large amount of energy is consumed to destroy it. Instead, radicals and ions are formed, the heat capacity of which is much less than the heat capacity of water and always has a negative value. Energy, which was spent for destruction, is applied to the total energy that exerts electrons and protons. The total energy contribution of all compounds formed during the compounds is sufficient to initiate both the burning process and the oxidation of various compounds. For the gas phase, an additional energy effect was achieved in the amount of 12-15% of the amount of energy released during the usual combustion of fuel.
Диссертация посвящена вопросам разработки технологий интенсификация эндотермических стадий реакций горения і окисления углеводородные газы и твердые углеводороды, которые базируются на использовании направленного действия искусственно созданной низкотемпературной плазм с упорядоченным движением «медленных» электронов в присутствии гетерогенного катализатора и определении оптимальных условий проведения этих процессов. Разработано новое направление в проведении окислительных процессов, которые базируются на использовании низкотемпературной плазмы с упорядоченным движением «медленных» электронов в присутствии гетерогенного катализатора для интенсификация эндотермических стадий реакций горения і окисления на катализаторах углеводородные газы и твердые углеводороды,. Искусственно созданная низкотемпературная неравновесная плазма, при её кратковременном действии на объект горения или окисления, дает возможность проводить химическую реакцию, которые в обычных условиях возможны при значительных энергозатратах, или протекают очень медленно. Минимизация энергозатрат в предлагаемых процессах достигаются при использовании катализе в зоне разряда. Для создания низкотемпературной плазмы предложено использовать барьерный и объемный разряд. Это направление получило название электронно-каталитический метод (ЭКМ). Использования этого метода в процессах горения и окисления позволяет расходовать на процесс интенсификации эндотермических стадий значительно меньшее количество энергии благодаря использованию энергии «медленных» элекронов, на образование которых влияет неравновесная плазма. При горении топливной смеси в предполумьяний зоне значительно уменьшается содержание воды, на разрушение которой расходовалось большое количество энергии. Вместо нее образуются радикалы и ионы, теплоемкость которых значительно меньше теплоемкости воды и всегда имеет отрицательное значение. Энергия, которая тратилась на разрушение, прилагается к суммарной энергии, оказывающих электроны и протоны. Суммарный энергетический вклад всех образующихся при соединений, достаточный, чтобы инициировать как процесс горения, так и окисления различных соединений. Для газовой фазы достигался дополнительный энергетический эффект в размере 12-15% от количества энергии, выделяемую при обычном сгорании топлива. В условиях ЭКМ на химический процесс влияют факторы: упругое и неупругое соприкосновения электронов и частиц, Ионизация, колебательное возбуждение и диссоциация молекул, температурная неоднородность между газовым потоком и потоком низкотемпературной плазмы, резонанс частоты колебаний молекул и электрического разряда. Существенное влияние оказывают диссоциативное прилипания, которое протекает при соприкосновении электронный с молекулой с образованием промежуточного агента - отрицательно заряженного иона, который затем разлагается на фрагменты, один из которых имеет отрицательный заряд и электронное возбуждение. При использовании низкотемпературной плазмы перед зоной реакции возникают резонансные частоты колебаний, которые могут вступать в резонанс с молекулой и инициировать первичные стадии горения и окисления сырья. Для электрического барьерного разряда характерно ряд температурных неоднородностей. При наложении электрического разряда на пламя под действием электромагнитного поля и потока электронов происходит направленное движение положительных частиц, которые образуются в пламени. Под действием электронов количество этих ионов увеличивается. Действие этого направленного движения ионизированных частиц увеличивает скорость процесса горения, благодаря более интенсивному движению частиц и изменении поверхности контакта. Использование ЭКМ интенсификации процесса горения твердого топлива позволяет повысить выход летучих соединений, в составе которых содержатся вещества, теплоты сгорания которых значительно выше, чем теплота сгорания веществ, которые образовались при обычном термолизе. Кроме того, использование ЭКМ приводит к образованию летучих соединений при значительно меньших температурах, что позволяет использовать избыток теплоты, образовавшийся на целевые нужды. Были проведены исследования горения и окисления углеводородных газов, в результате которых установлено: - оптимальные условия проведения электронно-каталитической интенсификации первичных стадий процессов горения и окисления газообразного и твердого топлива. Достигнуты значительные повышения выделения тепла для различных видов топлива. - влияние состава катализаторов на процесс окисления и горения газообразного топлива. Для ЭКМ наиболее эффективны катализаторы, содержащие никель и хром. - влияние параметров напряжения и формы синусоиды тока на процесс горения газообразного топлива. Наибольший эффект достигается при увеличении напряжения разряда и нижней синусоиде тока. Исследован процесс неполного окисления метана с использованием ЭКМ с образованием формальдегида и метанола. Получены зависимости формальдегида при разных составах исходной смеси и температуре. Для процесса сжигания твердого топлива определено влияние напряжения на процесс выделения газообразных веществ при термолизии топлива. Полученные зависимости выделение тепла от напряжения при сжигании антрацита, древесины и пеллет. При использовании ЭКМ в процессах горения достигнуто уменьшение выбросов оксидов углерода (II) до 52% и оксидов азота до 80% при сжигании твердого топлива. Составлены и решены математические модели процессов горения углеводородных газов, угля и древесины, процесса неполного окисления метана и формальдегид. Были предложены методы электронно-каталитической интенсификации процесса горения газообразного топлива, угля и древесины; метод синтеза формальдегида при атмосферном давлении.

The textbook provides up-to-date data on the composition and properties of hydrocarbons and other oil and gas compounds, on the physical and chemical methods and methods for separating and identifying oil components (molecular spectroscopy, mass spectrometry, NMR spectroscopy, electron paramagnetic resonance, atomic adsorption spectroscopy, neutron activation analysis). The chemistry and mechanism of thermal and catalytic transformations of oil components in the main processes of oil raw materials processing, as well as the problems of the origin of oil and the transformation of oil in the environment are considered. Meets the requirements of the federal state educational standards of higher education of the latest generation. It is intended for training in the course "Chemistry of oil and gas", for the preparation of bachelors, masters and certified specialists in the field of training "Oil and Gas business". It can be used for training in other areas in oil and gas universities and be of interest to specialists working in the field of chemistry and technology of oil refining and in other areas of the oil and gas industry.

The work is aimed at solving the problem of neutralization of persistent organic pollutants by catalytic methods. In order to identify the relationship between electronic and steric factors of carbenes with catalytic efficiency in the reaction of hydrodehalogenation of haloarenes, the parameters for estimating the ligand influences are proposed (electronic - Ie indices, Ph philicities, ED electron donicities, and EA electron acceptabilities, steric - dimerization energies) using theoretical methods (DFT, B3LYP5, RHF). Synthesis of new heteroaromatic carbenes of the series of sterically shielded 1,3-diarylphenanthro-[9,10-d]imidazol-2-ylidene, 1,3-diaryl-2-methy­lene­phenan­thro-[9,10-d]imidazoline, tetrahydropyrimidin-2-ylidene, 1,3-diaryl­imidazol-2-ylidene, 1,3,4-triaryl-1,2,4-triazol-5-ylidenes, their carbene complexes with palladium iodide, as well as the carbene complex of the superbasic anionic carbene 1,3-bis-(4-oxidophenyl)-imidazol-2-ylidene with nickel(II) ion. 1H and 13C NMR spectroscopy, mass spectrometry and X-ray diffraction study methods were used to establish the structures of the synthesized compounds. A high catalytic effect of a number of sterically shielded carbene complexes (2.4b, 3.5, 4.6a) in the reaction of hydrodehalogenation of p-dichlorobenzene haloarenes with sodium methoxide in isopropanol at 80 °С (TON 98000–110000) was revealed that can be applied to solve the problem of neutralization of persistent organic pollutants. The efficiency of catalysis by sterically open compounds 4.6b and 6.7 appeared to be low (TON 74, 128). The high catalytic effect of sterically shielded compounds is explained by the increased stability of the complexes under the conditions of an alkaline medium caused by metal alkoxides.

Nickel foam has a unique three-dimensional (3-D) network structure that helps to effectively utilize catalysts and is often used as an electrode support material for alkaline direct alcohol fuel cells. In this chapter, first, the effect of nickel foam thickness on cell performance is explored. The results show that the thickness affects both mass transfer and electron conduction, and there is an optimal thickness. The thinner the nickel foam is, the better the conductivity is. However, the corresponding three-dimensional space becomes narrower, which results in a partial agglomeration of the catalyst and the hindrance of mass transfer. The cell performance of 0.6 mm nickel foam electrode is better than that of 0.3 and 1.0 mm. Secondly, to fully exert the catalytic function of the catalyst even at a lower loading, a mixed acid-etched nickel foam electrode with lower Pd loading (0.35 mg cm−2) is prepared then by a spontaneous deposition method. The maximum power density of the single alkaline direct ethanol fuel cell (ADEFC) can reach 30 mW cm−2, which is twice the performance of the hydrochloric acid treated nickel foam electrode. The performance improvement is attributed to the micro-holes produced by mixed acids etching, which enhances the roughness of the skeleton and improves the catalyst electrochemical active surface area.

Yujiro Hayashi of Tokyo University of Science and Teruaki Mukaiyama of the Kitasato Institute developed (Chem. Lett. 2008, 37, 592) a reduction-oxidation method for converting primary, secondary (such as 1, with clean inversion) and tertiary alcohols to sulfides. Peter A. Crooks of the University of Kentucky found (Chem. Lett. 2008, 37, 528) that tetrabenzylpyrophosphate 5 was an effective agent for condensing an acid 4 with an amine 6 to give the amide 7. This protocol, that runs in near quantitative yield in an hour at room temperature, with all impurities readily removable by washing with aqueous base and aqueous acid, appears to be well-suited both for scale-up, and for solid-phase synthesis. Balchandra M. Bhanage of the University of Mumbai reported (Tetrahedron Lett. 2008, 49, 965) the reductive amination of aldehydes, including 8, and ketones to the corresponding amines, using H2 and an inexpensive Fe catalyst. André Charette of the Université de Montréal showed (J. Am. Chem. Soc. 2008, 130, 18) that the Hantzsch ester 12 , in the presence of Tf2O, reduced amides selectively to amines. Esters, epoxides, ketones, nitriles and alkynes were stable to these conditions. Matthew Tudge of Merck Rahway demonstrated (Tetrahedron Lett . 2008, 49, 1041) that Br2 in DME activated NaBH4 , allowing facile reduction of esters, including the congested diester 14, at ambient temperature. David J. Procter of the University of Manchester made (J. Am. Chem. Soc. 2008, 130, 1136) the remarkable observation that six-membered ring lactones such as 16 were reduced to the corresponding diol with SmI2 . Five-membered ring and seven-membered ring lactones were not reduced under these conditions. Bruce H. Lipshutz of the University of California, Santa Barbara devised (Organic Lett . 2008, 10, 289) a convenient and economical procedure for CuH, using Cu and an inexpensive ligand in catalytic amounts, with PMHS as the bulk reductant. The reduction of 18 presumably proceeds by electron transfer, as with dissolving metal reduction, delivering 19 with the more stable trans ring fusion. In the presence of t-BuOH as a proton source, the reduction goes on to the alcohol 20.

In a remarkable example of chemoselective oxidation, Scott J. Miller at Yale University identified (Nature Chem. 2012, 4, 990) a peptide catalyst that selectively epoxidized the 6,7-olefin of farnesol 1. Phil S. Baran at Scripps-La Jolla developed (Nature Chem. 2012, 4, 629) the Tz°sulfonate as a “portable desaturase” capable of site-specific C–H functionalization of complex molecules, such as in the conversion of peptide 3 to 4. A unique method for the preparation of α-oxygenated ketones was developed (Angew. Chem. Int. Ed. 2012, 51, 7799) by Laura L. Anderson at the University of Illinois at Chicago. Cross-coupling of cyclohexenyl boronic acid with N-hydroxyphthalimide produced N-enoxyphthalimides 5, which underwent a trihetero [3,3]-sigmatropic rearrangement to produce, after hydrolysis and protection, ketone 6. The enantioselective α-hydroxylation of oxindole 7 with atmospheric O2 catalyzed by pentanidium 8 was reported (Org. Lett. 2012, 14, 4762) by Zhiyong Jiang at Henan University and Choon-Hong Tan at Nanyang Technological University. A catalytic Baeyer-Villiger oxidation of ketones such as 10 using highly reactive metal borate salts was developed (Angew. Chem. Int. Ed. 2012, 51, 9093) by Kazuaki Ishihara at Nagoya University. Masatoshi Shibuya and Yoshiharu Iwabuchi at Tohoku University found (Org. Lett. 2012, 14, 5010) that nitroxyl radicals such as 13 catalyzed the oxidative cleavage of diols to carboxylic acids, such as in the conversion of 12 to 14. A highly reactive iridium catalyst 16 was reported (Angew. Chem. Int. Ed. 2012, 51, 12790) by Ken-ichi Fujita and Ryohei Yamaguchi at Kyoto University, which had high turnover numbers under mild conditions for the oxidation of alcohols including 15. Frank W. Foss Jr. at the University of Texas at Arlington developed (Org. Lett. 2012, 14, 5150) a biomimetic Dakin oxidation of electron-rich aryl aldehydes such as 18, using the flavin-type catalyst 19, Hantzsch ester, and oxygen as the terminal oxidant. Flavin-catalyzed oxidation of aldehydes using catalyst 22 was also reported (Org. Lett. 2012, 14, 3656) by David R. Carbery at the University of Bath. Carlos F. Barbas III at Scripps-La Jolla developed (Angew. Chem. Int. Ed. 2012, 51, 12538) a catalytic conversion of aldehydes such as 24 to the corresponding O-acyl N-hydroxyimides (cf. 25), which could be used for in situ amidations and esterifications.

Carbon nanomaterials (CNMs), especially carbon nanotubes and graphene, have been attracting tremendous attention in environmental analysis for rapid and cost effective detection of various analytes by electrochemical sensing. CNMs can increase the electrode effective area, enhance the electron transfer rate between the electrode and analytes, and/or act as catalysts to increase the efficiency of electrochemical reaction, detection, adsorption and removal are of great significance. Various carbon nanomaterials including carbon nanotubes, graphene, mesoporous carbon, carbon dots exhibited high adsorption and detection capacity. Carbon and its derivatives possess excellent electro catalytic properties for the modified sensors, electrochemical methods usually based on anodic stripping voltammetry at some modified carbon electrodes. Metal electrode detection sensitivity is enhanced through surface modification of working electrode (GCE). Heavy metals have the defined redox potential. A remarkable deal of efficiency with the electrochemical sensors can be succeeded by layering the surface of the working electrode with film of active electro-catalytic species. Usually, electro catalysts used for fabrication of sensors are surfactants, nano-materials, polymers, carbon-based materials, organic ligands and biomaterials.

As N. Selvakumar of Dr. Reddy’s Laboratories, Ltd., Hyderabad approached (Tetrahedron Lett. 2007, 48, 2021) the synthesis of phaseolinic acid 6, there was some concern about the projected cyclization of 2 to 3, as this would involve the coupling of two electron-deficient alkenes. In fact, the Ru-mediated ring-closing metathesis proceeded efficiently. The product unsaturated lactone 3 could be reduced selectively to either the trans product 4 or the cis product 5. There has been relatively little work on the synthesis of the higher branched sugars, such as the octalose 13, a component of several natural products. The synthesis of 13 (Organic Lett. 2007, 9, 4777) by Ulrich Koert of the Philipps-University Marburg also began with a Baylis-Hillman product, the easily-resolved secondary alcohol 8. As had been observed in other contexts, cyclization of the protected allylic alcohol 9a failed, but cyclization of the free alcohol 9b proceeded smoothly. V-directed epoxidation then set the relative configuration of the stereogenic centers on the ring. Ring-closing metathesis to construct tetrasubstituted alkenes has been a challenge, and specially-designed Ru complexes have been put forward specifically for this transformation. Oliver Reiser of the Universität Regensburg was pleased to observe (Angew. Chem. Int. Ed. 2007, 46, 6361) that the second-generation Grubbs catalyst itself worked well for the cyclization of 17 to 18. Again in this synthesis, catalytic V was used to direct the relative configuration of the epoxide. Intramolecular alkyne metathesis is now well-established as a robust and useful method for organic synthesis. It was also known that Ru-mediated metathesis of an alkyne with ethylene could lead to the diene. The question facing (Angew. Chem. Int. Ed . 2007, 46, 5545) Alois Fürstner of the Max-Planck-Institut, Mülheim was whether these transformations could be carried out on the very delicate epoxy alkene 21. In fact, the transformations of 21 to 22 and of 22 to 23 proceeded well, setting the stage for the total synthesis of Amphidinolide V 25.

A transition from geochemistry to biochemistry has been considered as a necessary step towards the emergence of primordial life. Nevertheless, how did this transition occur is still elusive. The chemistry underlying this transition is likely not a single event, but involves many levels of creation and reconstruction, finally reaching the molecular, structural, and functional buildup of complexity. Among them, one apparent question is: how the biochemical catalytic system emerged from the mineral-based geochemical system? Inspired by the metal–ligand structures in metalloenzymes, many researchers have proposed that transition metal sulfide minerals could have served as structural analogs of metalloenzymes for catalyzing prebiotic redox conversions. This assumption has been tested and verified to some extent by several studies, which focused on using Earth-abundant transition metal sulfides as catalysts for multi-electron C and N conversions. The progress in this field will be introduced, with a focus on the CO2 fixation and ammonia synthesis from nitrate/nitrite reduction and N2 reduction. Recently developed methods for screening effective mineral catalysts were also reviewed.

Graham J. Bodwell of Memorial University constructed (J. Org. Chem. 2012, 77, 8028) the third aromatic ring of defucogilvocarcin V 4 by the inverse electron demand addition of 1 to 2. The methyl ester 3 provided a useful departure point for the preparation of analogues of 4. Samuel J. Danishefsky of Columbia University and Sloan-Kettering found (Chem. Sci. 2012, 3, 3076) that the kinetic product from the addition of 5 to 6 could be equilibrated with a trace of acid to the more stable regioisomer 7. Oxidation to the enone followed by deoxygenation led to (+)-carissone 8. Michael E. Jung of UCLA developed (Org. Lett. 2012, 14, 5169) Me3Al-triflimide catalysts (not illustrated) for promoting difficult additions such as 5 to 6. Professor Danishefsky had demonstrated the efficacy of cyclobutenones as Diels-Alder dienophiles. More recently, he showed (J. Am. Chem. Soc. 2012, 134, 16080) that intramolecular cyclization of the cyclobutenone 9 led to the transfused, angularly substituted product 11. To prepare (+)-fusarisetin A 14, Emmanuel A. Theodorakis of the University of California San Diego needed (Chem. Sci. 2012, 3, 3378) the all-E geometric isomer of 12. He showed that equilibration of a 3:2 mixture with I2 led to a single dominant isomer that could be taken directly into the cycloaddition. Brian M. Stoltz of CalTech prepared (Angew. Chem. Int. Ed. 2012, 51, 9674) the triene 15 in enantiomerically enriched form by enantioselective allylation of a cycloheptenone derivative. Intramolecular cycloaddition of 15 established the tricyclic skeleton of 9β-presilphiperfolan-1α-ol 17. Ryan A. Shenvi of Scripps/La Jolla devised (J. Am. Chem. Soc. 2012, 134, 19604) the triene 19. Addition of 18 to 19 gave an intermediate that was unraveled with catalytic Yb(OTf)3 to give a trienone, which on heating engaged with the distal alkene to cyclize to 20. This set the stage for diastereoselective conjugate addition leading to 7-isocyano-11(20 ),14-epiamphilectadiene 21.

Carbon nanotubes and carbon nanofibers formed on a Ni-based catalytic support positioned at the fuel side of opposed flow oxy-flame are characterized by electron microscopy. Observed nanoforms include multiwalled carbon nanotubes (MWNTs), MWNT bundles, helically coiled tubular nanofibers, and ribbon-like coiled nanofibers with rectangular cross-section. The electric field method is applied to control structure and purity of formed carbon nanomaterial. A coating layer of nanotubes possessing a thickness of 35 to 40 microns and a high degree of alignment was formed along the surface of the catalytic probe with variation of probe potential. The method shows a great promise in controlling the structure and formation rate of flame generated carbon nanomaterials.

Pt/C and Pt/CNT catalysts were prepared by colloidal method using sodium citrate as a stabilizer, and ethylene glycol as the reducing agent and solvent. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results showed that the Pt particles were highly dispersed on the support and had a very narrow particle distribution with particle size range of 1.5–2.4 nm for both catalysts. Based on the electrochemical properties characterized by cyclic voltammetry, it was found that the as-synthesized electrocatalysts possessed a significantly higher catalytic activity than those of commercial Pt/C Johnson Matthey catalyst.

Controlling the detailed structures of single-walled carbon nanotubes (SWNTs) is imperative for realizing many SWNT applications, and understanding the SWNT growth mechanism is important to improve the growth techniques. In the present study, we performed SWNT growth by a catalytic chemical vapor deposition (CVD) method in wide temperature and pressure ranges, using a high-vacuum CVD chamber. We focused on low CVD gas pressure and low temperature conditions and investigated the SWNT growth mechanism. SWNTs were synthesized by using ethanol gas as the carbon source. As the catalyst, Co and Mo metal nano-particles deposited onto silicon substrates were used. SWNTs were grown via the reaction between ethanol gas and the catalytic metal nano-particles at high temperature. The ethanol gas pressure ranged from 10−3 Pa to 102 Pa, and the CVD temperature ranged from 400 to 900 °C. The yield of SWNTs was assumed to be proportional to the G-band intensity, which was measured by Raman scattering spectroscopy. SWNT samples were observed by scanning electron microscopy and transmission electron microscopy. An optimum CVD temperature existed for each ethanol gas pressure, and decreased with decreasing ethanol gas pressure. Moreover, SWNTs were grown even at 500 °C, when the ethanol gas pressure was low (less than 10−2 Pa). In this study, the minimum temperature and pressure at which SWNTs could be grown were 450 °C and 10−3 Pa. At low temperature and low CVD gas pressure, the activity of the catalyst and the growth rate of SWNTs were low, while the catalyst lifetime was long.

In the present study, a catalyst produced by flame spray pyrolysis (FSP) was evaluated for its ability to produce hydrogen-rich gas mixtures. Catalyst particles fabricated by a novel flame spray pyrolysis method resulting in a highly active catalyst with high surface-to-volume ratio were compared to a commercially produced catalyst (BASF F3-01). Both catalysts consisted of CuO/ZnO/Al2O3 of identical composition (CuO 40wt%, ZnO 40wt%, Al2O3 20wt%). Reaction temperatures between 220 and 295 °C, methanol-water inlet flow rates between 2 and 50 μl/min, and reactor masses between 25 and 100 mg were tested for their effect on methanol conversion and the production of undesired carbon monoxide. 100% methanol conversion can be easily achieved within the operational conditions mentioned for this flame-made catalyst — at reactor temperatures of 255 °C (achievable with non-concentrating solar collectors) more than 80% methanol conversion can be reached for methanol-water inlet flow rates as high as 10 μl/min. The FSP catalyst demonstrates similar catalytic abilities as the BASF, produces a consistent gas composition and produces lower overall CO production. Furthermore, the FSP catalyst demonstrates a better suitability to fuel cell use through its higher resistance to degradation and smaller production of carbon monoxide over long-term use. In the present study, the merits of using flame spray pyrolysis to produce CuO/ZnO/Al2O3 methanol steam reforming catalysts are examined, and directly compared to catalysts that are commercially produced in bulk pellet form, and then ground and sieved. The comparison is performed from several different perspectives: catalytic activity and CO production at various temperatures and fuel inlet flow rates; surface and structure characteristics are determined via scanning electron and transmission electron microscopy; surface area characteristics are determined via BET tests.

In the present study, a catalyst produced by flame spray pyrolysis (FSP) was evaluated for its ability to produce hydrogen-rich gas mixtures. Catalyst particles fabricated by a novel flame spray pyrolysis method resulting in a highly active catalyst with high surface-to-volume ratio were compared to a commercially produced catalyst (BASF F3-01). Both catalysts consisted of CuO/ZnO/Al2O3 of identical composition (CuO 40wt%, ZnO 40wt%, Al2O3 20wt%). Reaction temperatures between 220 and 295 °C, methanol-water inlet flow rates between 2 and 50 μl/min, and reactor masses between 25 and 100 mg were tested for their effect on methanol conversion and the production of undesired carbon monoxide. 100% methanol conversion can be easily achieved within the operational conditions mentioned for this flame-made catalyst — at reactor temperatures of 255 °C (achievable with non-concentrating solar collectors) more than 80% methanol conversion can be reached for methanol-water inlet flow rates as high as 10 μl/min. The FSP catalyst demonstrates similar catalytic abilities as the BASF, produces a consistent gas composition and produces lower overall CO production. Furthermore, the FSP catalyst demonstrates a better suitability to fuel cell use through its higher resistance to degradation and smaller production of carbon monoxide over long-term use. In the present study, the merits of using flame spray pyrolysis to produce CuO/ZnO/Al2O3 methanol steam reforming catalysts are examined, and directly compared to catalysts that are commercially produced in bulk pellet form, and then ground and sieved. The comparison is performed from several different perspectives: catalytic activity and CO production at various temperatures and fuel inlet flow rates; surface and structure characteristics are determined via scanning electron and transmission electron microscopy; surface area characteristics are determined via Brunauer-Emmett-Teller (BET) tests.

Solid oxide fuel cells (SOFCs) are promising as energy producing device, which at this stage of its development will require extensive analysis and benefit from numerical modeling at different time- and length scales. In this study, two models based on finite element method (FEM) and Lattice Boltzmann model (LBM), respectively, are evaluated and compared for an anode-supported SOFC. First, a 3D model is developed based on the FEM, using COMSOL, of a single SOFC operating at an intermediate temperature range. Heat, gas-phase species, momentum, ion and electron transport are implemented and coupled to the kinetics of the electrochemical reactions. Secondly, a 3D model of the porous anode of a SOFC is developed using LBM to investigate the effects of electrochemical reactions on the transport processes at microscale for 3 components (H2, H2O and O2−). Parallel computing in Python is employed through the program Palabos to capture the active microscopic catalytic reaction effects on the heat and mass transport. It is found that LBM can be effectively used at a mesoscale ranging down to a microscale and proven to effectively take care of the interaction between the fluid particles and the walls of the porous media. The 3D LBM model takes into account the transport of oxygen ions within the solid particles of the SOFC anode. Both the oxygen ions and the hydrogen are mainly consumed by the reaction layer. One of the improvements in this study compared to our previous (FEM) models is the captured 3D effects which was not possible in 2D. High current density spots are identified, where the electron transport distance is short and the oxygen concentration is high. The relatively thin cathode results in a significant oxygen mole fraction gradient in the direction normal to the main flow direction.

In the present work, the effective thermal conductivity of single walled carbon nanotube dispersions in water was investigated experimentally. Single-walled carbon nanotubes (SWNTs) were synthesized using the alcohol catalytic chemical vapour deposition method. The diameter distribution of the SWNTs was determined using resonance Raman spectroscopy. Sodium deoxycholate (SDC) was used as the surfactant to prepare the nanofluid dispersions. Photoluminescence excitation spectroscopy (PLE) reveals that majority of the nanotubes were highly individualized when SDC was employed as the surfactant. The nanofluid dispersions were further characterized using transmission electron microscopy, atomic force microscopy (AFM) and optical absorption spectroscopy (OAS). Thermal conductivity measurements were carried out using a transient hot wire technique. Nanotube loading of up to 0.3 vol% was used. Thermal conductivity enhancement was found to be dependent on nanotube volume fraction and temperature. At room temperature the thermal conductivity enhancement was found to be non-linear and a maximum enhancement of 13.8% was measured at 0.3 vol% loading. Effective thermal conductivity was increased to 51% at 333 K when the nanotube loading is 0.3 vol%. Classical macroscopic models fail to predict the measured thermal conductivity enhancement precisely. The possible mechanism for the enhancement observed is attributed to the percolation of nanotubes to form a three-dimensional structure. Indirect effects of Brownian motion may assist the formation of percolating networks at higher temperature thereby leading to further enhancements at higher temperature.

There is an urgent need in surface mount technology (SMT) for a nontoxic, reusable and low temperature bonding technique which can afford good mechanical support as well as electrical contact. Meanwhile in the nanotechnology, many excellent and unique structure-related properties such as the high mechanical strength, the high conductivity and the adhesion ability of gecko feet have been studied. Our lab proposes a new patterned structure of Au nanowire array named nanowire surface fastener (NSF), which cold bonding for surface mount technology can be realized at room temperature. Then various methods have been developed to fabricate nanowire, such as arc discharge, catalytic CVD growth and template synthesis, and so on. Among these methods, the template method has been widely used for preparing one-dimensional nanostructures such as metals, semiconductors, polymers, and other materials by electrochemical, electroless deposition or sol-gel technique. Especially anodic aluminum oxide template assisted way has attached considerable attention due to its unique structure properties, such as controllable pore diameter, extremely narrow pore size distribution with high densities, high aspect ratios, and ideally cylindrical pore shape. The well arranged porous anodic aluminum oxide membrane is fabricated from aluminum film by two steps zM oxalic acid electrolytes. The anodic aluminum oxide membrane was investigated for features such as pore size, interpore distance, and thickness by 40 V. It is important for fabrication of porous anodic aluminum oxide template to find out elimination of the barrier layer of oxide and the pore extending rate by 0.5 M phosphoric acid. Morphologies of surface of aluminum film between anodization process and the anodic aluminum oxide barrier layer was researched by using atomic force microscope and scanning electron microscope. Results showed that the anodic aluminum oxide having the same diameter of the pore and the well arranged pore array without branching channel was obtained. The diameter of the pore before the pore extending treatment is 42 nm and the diameter of the pore after the pore extending treatment for 30 minutes is 86 nm. It was found that the diameter of the pore increased per 15 nm by the pore extending treatment for 10 minutes. We fabricated the through-hole anodic aluminum oxide template and made Cu nanowire by the template of our own making. By using Cu nanowire, we try to produce nanowire surface fastener and evaluate its properties.

Silicon is an excellent transparent material for building IR micro-optical elements such as holographic and blazed gratings, and curvilinear micro-lenses. Shaping this material in 3D with mirror quality finish and single-digit microscale resolution is challenging due to its brittleness and high-melting point. To achieve these patterning characteristics, electron-beam grayscale lithography is typically selected to pattern a 2.5D feature onto a resist thin-film. Subsequently, the film features are transferred into the underlying silicon substrate by deep-reactive ion etching (DRIE) [1]. Small variations in the resist thickness lead to large shape distortions and reduced patterning repeatability. Further, the direct-write nature of e-beam lithography provides for slow throughput. Developing an alternative, parallel and scalable method to nanopatterning silicon with 2.5D geometrical control may impact emerging areas such as the design of sub-wavelength photonic and micro-optic elements for silicon photonics applications. Micro and nanoscale patterning of inorganic semiconductors (e.g. Silicon) requires traditional micromachining processes such as plasma-assisted etching (e.g. DRIE) and wet-etching (e.g. KOH etching). Neither of the aforementioned processes offer the capability to control the geometry in 3D with resolution in the nanoscale range. Thus, it is desirable to develop a low-temperature, low-stress and ambient approach to nanostructuring silicon in 3D. Wet etching approaches are good candidates for achieving such goal because they bypass the need for high-temperature processing and stressing materials beyond the elastic limit. Yet, they still rely on lithographical steps and offer limited sidewall control, restricting the scope of features it can produce. In recent literature, catalyst-based wet etching processes such as metal-assisted chemical etching (MACE) have been shown to pattern high-aspect ratio structures in semiconductors [2–3]. Some researchers have achieved control over the etch profile and etching direction, generating a limited set of interesting 3D objects [4–6]. The degrees of freedom in MACE patterning are still highly constrained due to limited control of the catalyst motion. Additionally, thin-film based MACE relies on intermediate 2D masking steps to pattern the catalyst which are often lithographical. Thus, this indirect approach to patterning silicon increases lead time and processing costs. In this paper, Mac-imprint, a direct imprint configuration of MACE, is introduced to overcome these fundamental barriers. It relies on the use of a catalytic stamp immersed in the etchant and brought against a silicon chip to selectively dissolve it at contact points. Stamps can be reused multiple times to pattern substrates with lifetimes that are dependent solely on its chemical and mechanical degradation. This process is inherently non-lithographic and occurs at room temperature. As a demonstration of its high-resolution capabilities, silicon wafers were patterned with a sinusoidal wave whose pitch and amplitude were 1 μm and 250 nm, respectively. The patterned surface RMS error from the ideal surface was measured to be 13 nm. The key drawback of this approach is the generation of porous defects near the vicinity of the contact interface between stamp and substrate. Its spatial distribution is qualitatively discussed in the context of the diffusion model of MACE [7].

The production of hydrogen was investigated in a fixed bed tubular reactor via steam reforming of methanol using CuO/ZnO/Al2O3 catalysts prepared by wet impregnation method and characterized by measuring surface area, pore volume, X-ray diffraction pattern and scanning electron microscopy photographs. The SRM was carried out at atmospheric pressure, temperature 493–573 K, steam to methanol molar ratio 1–1.8 and W/F 3 to 15. Effects of reaction temperature, contact-time, steam to methanol molar ratio and zinc content of catalyst on methanol conversion, selectivity and product yields were evaluated. The addition of zinc enhances the methanol conversion and hydrogen production. The excess steam promotes the methanol conversion and suppresses the carbon monoxide formation. Different strategies have been mentioned to minimize the carbon monoxide formation for the steam reforming of methanol to produce fuel cell grade hydrogen. Optimum operating conditions with appropriate composition of catalyst has been found to produce more selective hydrogen with minimum carbon monoxide. The reaction mechanism has been proposed based on the product distribution. The kinetic model available in literature fitted well with the experimental results.