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Catalytic Oxidation (catalytic + oxidation)
Selected AbstractsElectrochemically Initiated Catalytic Oxidation of 5-Thio-2-Nitrobenzoic Acid (TNBA) in the Presence of Thiols at a Boron Doped Diamond Electrode: Implications for Total Thiol DetectionELECTROANALYSIS, Issue 21 2003Olga Nekrassova Abstract The electrochemical response of 5,5-dithiobis(2-nitrobenzoic acid) (DTNB) to increasing additions of thiol species has been examined at a boron doped diamond electrode. A reaction has been shown to occur with a range of biologically relevant thiols and proceeds via a CECC' process. A total thiol detection methodology has been developed showing that the sensitivities of the standard addition plots are independent of the individual thiol species added to the solution. The analytical utility of the reaction process has been assessed using chronoamperometry with the corresponding data producing detection limits of 5.7,,M, 4.4,,M and 5.8,,M for the detection of cysteine, homocysteine and glutathione respectively. [source] Polyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] ChemInform Abstract: Catalytic Oxidation of Hydrazo Derivatives Promoted by a TiCl3/HBr System.CHEMINFORM, Issue 13 2008Eyal Drug Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Catalytic Oxidation of Thiols to Disulfides Using Iodine and CeCl3×7H2O in Graphite.CHEMINFORM, Issue 4 2008Claudio C. Silveira Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A New and Highly Effective Method for Catalytic Oxidation of Alcohols to the Corresponding Carbonyl Compounds Using the Tris[(2-oxazolinyl)phenolato] manganese(III)/Oxone®/n-Bu4NBr Oxidation System.CHEMINFORM, Issue 12 2004Mojtaba Bagherzadeh Abstract For Abstract see ChemInform Abstract in Full Text. [source] Catalytic Oxidation of Furan and Hydrofuran Compounds.CHEMINFORM, Issue 20 2003Part 7. No abstract is available for this article. [source] ChemInform Abstract: Catalytic Oxidation of Alcohols with Ru(Pybox)(Pydic) Complex.CHEMINFORM, Issue 33 2002Seiji Iwasa Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Catalytic Oxidation of 4-Piperidone-3-carboxylates with Manganese(III) Acetate in the Presence of 1,1-Disubstituted Alkenes.CHEMINFORM, Issue 12 2001Ryoukou Kumabe Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Adsorptive Stripping Voltammetric Detection of Tea Polyphenols at Multiwalled Carbon Nanotubes-Chitosan Composite ElectrodeELECTROANALYSIS, Issue 6 2009Deyin Guo Abstract This study reports the catalytic oxidation and detection of tea polyphenols (TPs) at glassy-carbon electrode modified with multiwalled carbon nanotubes-chitosan (MWCNTs-CS) film. The adsorption of TPs at the surface of the MWCNTs through ,,, conjugation prevents the aggregation of nanotubes and induces a stable MWCNTs suspension in water over 30 days. Based on the adsorptive accumulation of polyphenols at MWCNTs, TPs is sensitively and selectively detected by adsorptive stripping voltammetry. The accumulation conditions and pH effect on the adsorptive stripping detection were examined. The linear range was found to be 100 to 1000,mg L,1 with a detection limit of 10,mg L,1 (S/N=3) for 2.5,min accumulation. Additionally, the MWCNTs-CS electrode is easily renewed by applying positive potential to remove the adsorbed TPs. This method was successfully applied to determine TPs in commercially available teas with satisfied result compared with that of conventional spectrometric analysis. [source] Multilayer Assemblies Consisting of Tri-Vanadium-Substituted Heteropolyanions and Its Electrocatalytic PropertiesELECTROANALYSIS, Issue 14 2003Shengyong Zhai Abstract We describe the controlled fabrication of ultrathin multilayer films consisting of tri-vanadium- substituted heteropolytungstate anions (denoted as P2W15V3) and a cationic polymer of quaternized poly (4-vinylpyridine) partially complexed with osmium bis(2,2,-bipyridine) (denoted as QPVP-Os) on the 4-aminobenzoic acid (4-ABA) modified glassy carbon electrode (GCE) surface based on layer-by-layer assembly. Cyclic voltammetry and UV-vis absorption spectrometry have been used to easily monitor the thickness and uniformity of thus-formed multilayer films. The V-centered redox reaction of P2W15V3 in the multilayer films can effectively catalyze the reduction of BrO and NO. The resulting P2W15V3/QPVP-Os multilayer film modified electrode behaves as a much promising electrochemical sensor because of the low overpotential for the catalytic reduction of BrO and NO, and the catalytic oxidation of ascorbic acid. [source] Cryogenic condensation: A cost-effective technology for controlling VOC emissionsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2002Robert J. Davis Cryogenic condensation is an extremely cost-effective technology for controlling emissions of Volatile Organic Compounds (VOCs) from chemical processing facilities under certain conditions. This paper describes the technology and provides the case history of an application in the pharmaceutical industry, in which its cost effectiveness was compared with a range of alternative technologies, including thermal oxidation, catalytic oxidation, flaring, carbon adsorption, and scrubbing. Because the facility already used significant quantities of liquid and gaseous nitrogen for inerting, blanketing, and purging, a very convenient cold source for cryogenic condensation was already present. On a lifetime cost basis, cryogenic condensation was significantly less costly than all other technologies evaluated. [source] The Nanocrystalline Nickel with Catalytic Properties on Methanol Oxidation in Alkaline MediumFUEL CELLS, Issue 5 2009R. M. A. Tehrani Abstract The hexagonal closed packed (hcp) nanocrystalline nickel (Ni), with an average diameter of 9.7,±,2.27,nm was deposited uniformly on composite graphite (CG) by the rapid scanning (6,500,mVs,1) voltammetry technique. The hcp-nano Ni-modified CG electrode was investigated for the catalytic oxidation of methanol in alkaline medium through the formation of NiOOH. A high anodic current was obtained at peak potential of +570,mV vs Ag/AgCl. Both the scan rate and the methanol concentration affected the oxidation of methanol. The results showed that catalytic activity had increased with decrease in Ni particle diameter. It was also shown that the hcp-nano Ni/CG modified electrode was the most efficient catalyst in the oxidation of methanol. [source] Theoretical study of the CO catalytic oxidation on Au/SAPO-11 zeoliteINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2010Beulah Griffe Abstract Quantum chemistry calculations were carried out, using ONIOM2 methodology, to investigate the CO adsorption and oxidation on gold supported on Silicoaluminophospates (SAPO) molecular sieves Au/SAPO-11 catalysts. Two models were studied, one containing one Au atom per site (AuSAPO-11), and the other with two Au atoms per site (Au2SAPO-11). The results reveal that the CO adsorption and oxidation are exothermic on Au/SAPO11 with an ,E of ,41.0 kcal/mol and ,E = ,52.0 kcal/mol, for the adsorption and oxidation, respectively. On the Au2SAPO-11 model, the CO adsorption and oxidation reaction occur, with a ,E of ,29.7 kcal/mol and ,52 kcal/mol, respectively. According to our results, the oxidation reaction exhibits an Eley-Rideal type mechanism with adsorbed CO. The theoretical calculations reveal that this type of material could be interesting to disperse Au and consequently to strengthen its catalytic use for different reactions. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2573,2582, 2010 [source] Polyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] Loss of Chaotic Trabecular Structure in OPG-Deficient Juvenile Paget's Disease Patients Indicates a Chaogenic Role for OPG in Nonlinear Pattern Formation of Trabecular BoneJOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2004Phil Salmon PhD Abstract The RANK-RANKL-OPG system of osteoclast regulation may play a key role in determining chaotic structure in trabecular bone. Iliac trabecular bone from juvenile Paget's disease patients deficient in functional OPG shows parallel, anisotropic structure instead of normal chaotic structure. Evidence from experimental systems suggests that RANK-RANKL-OPG controls key nonlinear "chaogenic" parameters, such as friction, forcing frequency, feedback, and boundary forcing. The RANK-RANKL-osteoprotegerin (OPG) system of osteoclast regulation may play a key role in determining chaotic structure in trabecular bone. Iliac trabecular bone from juvenile Paget's disease (JPD) patients deficient in functional OPG shows parallel, anisotropic structure instead of normal chaotic structure. Evidence from experimental systems suggests that RANK-RANKL-OPG controls key nonlinear "chaogenic" parameters, such as friction, forcing frequency, feedback, and boundary forcing. The Belousov-Zhabotinsky reaction-diffusion system, the catalytic oxidation of CO on platinum surfaces, and thermal diffusion in liquid helium allow visualization of nonlinear emergent patterns such as labyrinthine structures, turbulence, and cellular structures, all of which bear some resemblance to trabecular bone. In JPD, the gene for OPG (TNFRSF11B) is subject to an inactivating mutation, leading to increased resorption and accelerated remodeling. Histomorphometric images of iliac crest trabecular bone from teenagers suffering from JPD show a highly unusual array of parallel, regular trabecular plates, instead of the typical chaotic, fractal patterns of normal trabecular bone. Loss of OPG function is associated with a change from chaotic to regular structure, suggesting that the RANK-RANKL-OPG system is controlling key nonlinear "chaogenic" parameters. Looking at trabecular bone from the perspective of nonlinear pattern formation may help understand other phenomena, such as the marked dependence of trabecular bone's architectural and mechanical quality on remodeling rate independent of the trabecular bone mass. [source] NOx storage and reduction with propylene on Pt/BaO/aluminaAICHE JOURNAL, Issue 10 2004Rachel L. Muncrief Abstract An experimental study was carried out of periodically operated NOx (NO + NO2) storage and reduction on a model Pt/BaO/Al2O3 catalyst powder. The effect of the reductant (propylene) injection policy on time-averaged NOx conversion was evaluated in terms of feed composition and temperature, reductant pulse duration, and overall cycle time. Conditions giving time-averaged NOx conversions exceeding 90% were identified. The reductant-to-oxidant ratio during the injection and the total cycle time are both found to be critical factors to achieve high conversion. The time-averaged conversion is bounded above and below by the steady-state conversions obtained with feeds having the same compositions as that during the rich and lean part of the cycle, respectively. For a fixed supply of propylene, short pulses of high concentration are much more effective than longer pulses of reduced concentration. The NOx conversion achieves a maximum value at an intermediate overall cycle time when the propylene pulse of fixed duty fraction is net reducing. High conversions are sustained over a wide temperature window (200,400°C). A simple storage,reduction cycle is proposed that elucidates the main findings in the study. The key factor for high NOx conversion is the temporal production of oxygen-deficient conditions coupled with high catalyst temperatures, both resulting from the intermittent catalytic oxidation of propylene. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2526,2540, 2004 [source] Spectrofluorimetric determination of vitamin B1 using horseradish peroxidase as catalyst in the presence of hydrogen peroxideLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2009Mir Azam Khan Abstract In this work a new spectrofluorimetric method for the determination of vitamin B1, based on the catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2), has been developed. Non-fluorescent vitamin B1 was easily converted through catalytic oxidation in alkaline medium into a fluorescent compound, even without exposure to light. The linear range for vitamin B1 observed was 0.026,16.83 µg/mL (RSD = 1.75%). The correlation coefficient for the calibration curve and limit of detection were found to be 0.9964 and 0.015 µg/mL, respectively. The developed method is practical, simple, sensitive and relatively free from interference by coexisting substances and has been successfully applied for the determination of vitamin B1 in pharmaceutical preparations. Copyright © 2008 John Wiley & Sons, Ltd. [source] Catalytic effect of ferricyanide between myoglobin and luminol and effect of temperatureLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 2 2007Xin Gao Abstract Specific catalytic oxidation of oxymyoglobin (MbO2) and luminol by ferricyanide was studied in a flow-injection system. MbO2 in different redox states (ferric and ferrous) was oxidized to Mb(FeIII) by ferricyanide, and then specific binding of the ferrocyanide anion to Mb(FeIII) to the His 119 (GH1) region accelerated the electron transfer between Mb(FeIII) and luminol, which produced a chemiluminescence (CL) signal at 425 nm. The increased CL emission was correlated with the myoglobin concentration in the range 0.16,7.5 µg/mL. Thermogravimetry and differential scanning calorimetry were used to investigate the temperature effects on this reaction. The results showed that the CL intensity in the presence of myoglobin changed considerably with heating in the range 15,50°C, and the maximal CL intensity was observed at 40°C, corresponding to the glass transition temperature of myoglobin. The effect of different ligands and interferences were also studied. Copyright © 2006 John Wiley & Sons, Ltd. [source] The effect of mixing on the generation of alkaline peroxymonosulfateTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2001Mohammad Shaharuzzaman Abstract Alkaline peroxymonosulfate (PMS) has been successfully used in the laboratory for bleaching kraft pulp. Used in conjunction with oxygen, the addition of 1.0% PMS to an oxygen delignification system can increase delignification from 49% to 73% without reducing pulp strength. One promising method of achieving this is the catalytic oxidation of sodium sulfite with oxygen. Laboratory generation of PMS is readily achieved, but typically at low yields and low concentrations. Here we investigate the mixing-sensitivity of its generation under semi-batch reaction conditions using a number of laboratory mixers. Our primary focus was on the energy dissipation in the reaction zone and its effect on PMS yield and concentration. By managing the chemical contacting strategy and increasing energy dissipation in the reaction zone we were able to generate PMS at higher yields and concentrations than previously reported. On a utilisé avec succès le péroxymonosulfate alcalin (PMS) au laboratoire pour effectuer le blanchiment d'une p,te kraft. En association avec de l'oxygène, l'ajout de 1,0% de PMS à un système de délignification à l'oxygène peut accro,tre la délignification de 49% à 73% sans réquire la résistance de la p,te. Une méthode prometteuse pour y parvenir réside dans l'oxydation catalytique du sulfite de sodium avec l'oxygène. La production de PMS en laboratoire est facile à réaliser, mais typiquement avec un rendement faible et à basse concentration. On étudie ici la sensibilité au mélange de sa production dans des conditions de réaction semi-continues à l'aide de plusieurs mélangeurs de laboratoire. On s'intéresse principalement à la dissipation d'énergie dans la zone de réaction et à ses effets sur le rendement et la concentration du PMS. En gérant la stratégie de fonctionnement par contact chimique et en augmentant la dissipation d'énergie dans la zone de réaction, on a pu produire du PMS à des rendements et concentrations supérieurs à ceux présentés antérieurement. [source] Palladium,Schiff base,triphenylphosphine catalyzed oxidation of alcoholsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2010Dileep R. Abstract Novel palladium(II)- N -(2-pyridyl)- N,-(5- R -salicylidene) hydrazine triphenylphosphine complexes were synthesized and characterized by UV, IR, 1H NMR and 31P NMR spectral analysis, C, H, N analysis and magnetic susceptibility measurements. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of N -methyl-morpholine- N -oxide as oxidant. The oxidation reactions were carried out in dichloromethane. A mechanistic study of the above reactions has been proposed. Copyright © 2010 John Wiley & Sons, Ltd. [source] Modified Microperoxidases Exhibit Different Reactivity Towards Phenolic SubstratesCHEMBIOCHEM, Issue 12 2004Corrado Dallacosta Dr. Abstract The reactivity of several microperoxidase derivatives with different distal-site environments has been studied. The distal-site environments of these heme peptides include a positively charged one, an uncharged environment, two bulky and doubly or triply positively charged ones, and one containing aromatic apolar residues. The reactivity in the catalytic oxidation of two representative phenols, carrying opposite charges, by hydrogen peroxide has been investigated. This allows the determination of the binding constants and of the electron-transfer rate from the phenol to the catalyst in the substrate/microperoxidase complex. The electron-transfer rates scarcely depend on the redox and charge properties of the phenol, but depend strongly on the microperoxidase. Information on the disposition of the substrate in the adducts with the microperoxidases has been obtained through determination of the paramagnetic contribution to the1H NMR relaxation rates of the protons of the bound substrates. The data show that the electron-transfer rate drops when the substrate binds too far away from the iron and that the phenols bind to microperoxidases at similar distances to those observed with peroxidases. While the reaction rate of microperoxidases with peroxide is significantly smaller than that of the enzymes, the efficiency in the one-electron oxidation of phenolic substrates is almost comparable. Interestingly, the oxyferryl form of the triply positively charged microperoxidases shows a reactivity larger than that exhibited by horseradish peroxidase. [source] Volcano Relation for the Deacon Process over Transition-Metal OxidesCHEMCATCHEM, Issue 1 2010Felix Studt Dr. Abstract We establish an activity relation for the heterogeneous catalytic oxidation of HCl (the Deacon Process) over rutile transition-metal oxide catalysts by combining density functional theory calculations (DFT) with microkinetic modeling. Linear energy relations for the elementary reaction steps are obtained from the DFT calculations and used to establish a one-dimensional descriptor for the catalytic activity. The descriptor employed here is the dissociative chemisorption energy of oxygen. It is found that the commonly employed RuO2 catalyst is close to optimal, but that there could still be room for improvements. The analysis suggests that oxide surfaces which offer slightly weaker bonding of oxygen should exhibit a superior activity to that of RuO2. [source] Determination of Optimum Conditions and the Kinetics of Methanol OxidationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2010A. H. Ulukardesler Abstract In this study, the catalytic oxidation of methanol to formaldehyde was investigated in a laboratory-scale fixed-bed catalytic reactor, under a large number of different conditions. Iron-molybdate catalysts supported by silica or alumina with a molybdenium/iron (Mo/Fe) ratio of 1.5, 3 and 5 were studied for the gas phase reaction. In order to obtain the optimum conditions, six different temperatures in the range of 250,375,°C and three different space times of 50.63, 33.75 and 20.25 g/(mol/h) were investigated. After determining the optimum conditions for this reaction, experiments aimed at understanding the reaction kinetics, were carried out. These experiments were performed on the catalyst favoring the formation of formaldehyde, which has a (Mo/Fe) ratio of 5 on a silica support. Seven reaction models derived by the mechanisms cited in the literature were tested to elucidate the kinetics of the reaction and the surface reaction controlling model was found to be the most suitable reaction mechanism. [source] Model-Aided Design of a Three-Phase Gas-Lift Reactor for Oxidation Accompanied by Catalyst Reversible DeactivationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2009Z. Gogová Abstract A mathematical model of a three-phase gas-lift reactor (GLR) is developed to aid the design of a target reactor for simultaneous substrate catalytic oxidation in riser and a deactivated reactivation catalyst in the downcomer section of the multifunctional reactor. In the GLR model, the hydrodynamics of a real GLR and the kinetics of glucose oxidation by air over a palladium catalyst are incorporated. The GLR model searches for the optimal geometry of the target reactor. With regard to the GLR optimal geometry, the reactor productivity is maximal for given input operational conditions. An algorithm of the GLR model is presented together with simulation results of the target GLR and with insight into the parametric sensitivity of the model. Effects of the reaction components concentrations and the gas-phase superficial velocity on the location of the target reactor optimal geometry and on the reactor productivity are discussed. [source] Catalytic Liquid Phase Oxidation of Toluene to Benzoic AcidCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2008A. Gizli Abstract The production of benzoic acid from toluene in the liquid phase with pure oxygen was studied. Investigations have been carried out with a view to determining the most suitable reaction conditions with respect to operating variables including oxygen flow rate, reaction temperature, batch time and catalyst loading. In a series of batch experiments carried out at 4,atm, the optimum values of mole ratio of oxygen to toluene, temperature, reaction time, and catalyst loading were found to be 2, 157,°C, 2,h and 0.57,g/L, respectively. In addition, a kinetic study was carried out by taking into consideration the optimum reaction conditions. The model dependent on the formation of benzyl radical was found to be feasible for describing the catalytic oxidation of toluene to benzoic acid in the liquid phase. The activation energy was determined as 40,kJ/mol. [source] Oxidation of Benzene to Maleic Anhydride in a Fluidized Bed ReactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2007C. Uraz Abstract In this project, the selective oxidation of benzene to maleic anhydride (MAN) was studied. Gas phase catalytic oxidation of benzene was carried out in a laboratory scale fluidized bed reactor on six different types of catalysts, which have different compositions. Effects of temperature, flow rates of benzene and air and catalyst type on the reaction selectivity were investigated at atmospheric pressure. The experiments were performed over a temperature range of 325 to 400,°C, a space-time (W/FA0) range from 11.28,×,105 to 31.9,×,105 g,s,mol,1, and benzene/air mole ratio changes between 0.0109 and 0.0477. It was seen that conversion of benzene to MAN increased with increasing temperature for the catalysts supported by silica gel, aluminum oxide and titanium oxide. From the results it was found that conversion increased with increasing flow rate of air. When the comparison of the catalysts were made, it could be said that catalysts supported by silica gel showed higher MAN conversions. So it can be concluded that catalysts supported by silica gel were more suitable catalysts for benzene oxidation to MAN in a fluidized bed reactor. [source] Simulation and Optimization of an Adiabatic Multi-Bed Catalytic Reactor for the Oxidation of SO2CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2007A. Nodehi Abstract A software package was developed for the simulation and optimization of a multi-bed adiabatic reactor for the catalytic oxidation of SO2, using a heterogeneous plug flow model. The orthogonal collocation (OC) technique with up to eight collocation points was used for the solution of a nonlinear, two-point boundary value differential equation for the catalyst particle, and it was shown that the use of the OC technique with two collocation points can describe the system well. Because of the nonlinear behavior of the effectiveness factor along the bed, optimal catalyst distribution between the beds and corresponding inlet temperatures were determined by two methods, including: the use of (1) intrinsic or (2) actual rate of reaction in the optimization criteria. The results showed that for the second case, the minimum amount of the catalyst can be reached at lower temperatures, the amount of catalyst required is always less, and the number of beds is greater than or equal to that of the first case. [source] Kinetic Evidence for the Influence of Subsurface Oxygen on Palladium Surfaces Towards CO Oxidation at High TemperaturesCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2009Chinnakonda Abstract Transient state kinetics of the catalytic oxidation of CO with O2 on Pd-surfaces has been measured under isothermal conditions by using a molecular beam approach. Systematic studies were carried out as a function of reaction temperature and CO+O2 composition. With sufficient kinetic evidence, we have demonstrated the positive influence of subsurface oxygen towards CO-adsorption and oxidation to CO2 at high temperatures (600,900,K) on Pd-surfaces, and the likely electronic nature of the surface changes with oxygen in the subsurface. These studies also provide a direct proof for CO-adsorption with a significantly reactive sticking coefficient at high temperatures on Pd-surfaces exhibiting a significant subsurface O-coverage. [source] A Novel and Efficient System of a Visible-Light-Responsive Organic Photoelectrocatalyst Working in a Water PhaseCHEMPHYSCHEM, Issue 5 2004Toshiyuki Abe Prof. The best of both worlds: An organic bilayer, composed of a perylene derivative (PV) and a phthalocyanine (H2Pc), was found to be a novel example of a photoanode involving a catalytic oxidation in water (see graphic). Based on the action spectrum for photocurrent, it is noted that the widespread visible light absorption (<750 nm) by only the PV can efficiently induce the photoanodic current generation at the interface of H2Pc/water coupled with the hole-conducting character of H2Pc. [source] Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)CHINESE JOURNAL OF CHEMISTRY, Issue 2 2010S. Ali Hosseini Abstract Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM-5 catalysts under atmospheric pressure. Nanostructure of ZSM-5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM-5 was determined using EDX, ICP-AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu-ZSM-5 catalysts than those of parent ZSM-5 and HZSM-5, which revealed catalytic role of copper ions in the Cu-ZSM-5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu-ZSM-5 catalysts. Furthermore, the catalytic activity of Cu-ZSM-5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co-feed had an inhibitive effect on conversion of organic compounds over the Cu-ZSM-5 catalysts. [source] | ||||||||||||||||||||||||||||||||||