bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absorption of chlorine into aqueous sodium carbonate solutions and desorption of carbon dioxide
Authors: Hikita H. , Asai S. , Konishi Y. , Seo K. 
Published: March 2009

AbstractThe absorption of pure chlorine into aqueous sodium carbonate solutions accompanied by the desorption of carbon dioxide was studied both theoretically and experimentally. The absorption rates of chlorine and the desorption rates of carbon dioxide were measured at 25°C using a baffled agitated vessel operated batchwise. The experimental results were analyzed with the chemical absorption theory based on the Lévěque model. The measured absorption and desorption rates were in good agreement with the theoretical predictions.
Effectiveness and performance of a catalyst pellet with bimodal kinetics
Authors: Chitnis G. K. , Wolf E. E. 
Published: March 2009

AbstractA theoretical analysis of the performance of a bimodal catalyst pellet which contains two different active components exhibiting different kinetics is presented in this paper. The isothermal interphase‐intraphase effectiveness of such bimodal catalysts with a bimolecular Langmir type kinetics (i.e. noble metal) and a first order kinetics (i.e. base metal oxide) is coupled with the continuity equation for a fixed bed reactor and a continuously stirred tank catalytic reactor. The catalysts with mixed mode kinetics exhibit a behaviour that is less affected by concentration changes than the single component catalyst. Reactor performance depends on the noble metal fraction but not in direct proportion. Thus in some cases conversion reaches high levels at fractional values of noble metal loadings which would in theory allow for equivalent performance with savings in noble metal component.
Acidophilic fungus SCP from peat hydrolyzate
Authors: Boa Jacques M. , Leduy Anh 
Published: March 2009

AbstractAn unidentified newly isolated acidophilic fungus was cultivated in peat hydrolyzate for potential use as single‐cell protein (SCP). At the optimal medium composition of (NH4)2SO4 0.5%. K2HPO4 0.5%, MgSO4 0.04%, and an initial pH of 2.5, the maximum biomass concentration of 10.4 g/L and the total carbohydrate reduction of 69.7% were obtained from the batch cultivation in an open‐pond bioreactor. The fungal biomass contained 24.3% protein, 1.7% lipid, 61.2% carbohydrate and 12.8% ash on the dry weight basis. The content of lysine, threonine, methionine, leucine and isoleucine in peat hydrolyzate‐grown fungus was superior to the FAO standard.
Interfacial tensions of oil, water, chemical dispersant systems
Authors: Mackay Donald , Hossain Khon 
Published: March 2009

AbstractOil‐water interfacial tension measurements are reported for systems of crude oils, distilled and salt water, and chemical dispersants, using the spinning drop technique. By varying the amount of dispersant and the volumetric ratio of water to oil it is possible to deduce an effective oil‐water partition coefficient for the interfacial tension reducing species and to suggest a relationship between the extent of interfacial tension reduction and dispersant concentration. The implications of the results in assessing the mechanism and effectiveness of the chemical dispersion process are discussed.
A method of estimating entropies of coals and coal liquids
Authors: Ikumi S. , Luo C. D. , Wen C. Y. 
Published: March 2009

AbstractA method for estimating entropies of both solid and liquid fuels is proposed. An example showing calculation of availability of coal is presented. Entropy and availability of coal calculated are compared with those obtained by other methods. Deviations among different methods examined are discussed.
The nature of the active sites in cumene cracking on amorphous silica aluminas
Authors: Marczewski M. , Wojciechowski B. W. 
Published: March 2009

AbstractWe present evidence which indicates that the nature of the active sites is the same for amorphous catalysts as it is for crystalline alumina silicate cracking catalysts. The only differences we find in the various cracking catalysts lie in the total concentrations of active sites and in the ratio of Bronsted to Lewis sites.In view of this, and because even zeolites have only a fraction of their cationic sites active in cumene cracking, we suggest that it is possible that a silica alumina catalyst could exist that is more active by as much as an order of magnitude than any catalyst presently available for cumene cracking.
Agitation de fluides pseudoplastiques par un agitateur bipale
Authors: Et J. Bertrand , Couderc J. P. 
Published: March 2009

AbstractIn the present work, results are given on the agitation of pseudoplastic fluids by a two‐blade stirrer; the method used has been a numerical analysis. The fluids simulated follow either the Ostwald de Waele Law or the Carreau's one. The (flow) streamlines, the velocity vector, the apparent viscosity, the stresses and the power consumption are presented. The Metzner‐Otto theory is checked and a correlation is proposed for the power number. Finally, some characteristic values obtained on the blade tips are indicated.
A mass transfer study of a new electrochemical reactor stirred by gases evolved at the counter electrode
Authors: Sedahmed G. H. , Shemilt L. W. 
Published: March 2009

AbstractMass transfer coefficients were measured for the deposition of copper from acidified copper sulphate solution at a horizontal cylinder cathode stirred by oxygen evolved at a horizontal lead anode placed below the cylinder. Variables studied were: oxygen discharge rate, electrolyte concentration and cylinder diameter. Oxygen discharge was found to increase the rate of mass transfer by a factor ranging from 1.5 to 5 over the natural convection value depending on the rate of oxygen discharge at the lead anode. The data were correlated by the equation: J = 25.0 Re−0.53Mass transfer coefficients measured at an array of horizontal cylinders agreed with the results for single cylinders. A new electrochemical reactor built of a set of parallel arrays of horizontal cylinders and stirred by the counter electrode gases is proposed as offering an efficient way of stirring with no external stirring power requirement.
A study of agglomeration of coal‐ash in fluidized beds
Authors: Basu P. 
Published: March 2009

AbstractExperimental data on agglomeration of coal‐ash particles in a fluidized bed have been presented. It has been observed that above the “initial sintering temperature”, the ash particles are defluidized at velocities above their minimum fluidization velocity. The expression for minimum fluidization velocity has been modified by including a force‐term due to the phenomenon of sintering in addition to those due to drag, gravity and kinetic energy.
The kinetics of absorption of so3 in calcium and magnesium oxides
Authors: Thibault J. Dean , Steward Frank R. , Ruthven Douglas M. 
Published: March 2009

AbstractResults of an experimental study of the absorption of SO3 by CaO and MgO particles are reported. Uptake rates are shown to be controlled by intragranular diffusion and are essentially independent of gross particle size in the range 0.06‐0.33 mm. The data can be correlated by the swelling grain model of Georgakis et al.(12). The uptake rate in MgO is considerably faster than in CaO but this difference is shown to be attributable mainly to differences in grain size and porosity. Activation energies for diffusion of SO3 through the product layer are about 40 kJ/mol for both absorbents and diffusivities at 800 K are about 10−8. cm2. S−1. The results are discussed in relation to the development of an efficient dry scrubbing flue gas desulphurization process.
Ozonation of organic compounds in alkaline aqueous media
Authors: Imamura S. , Umena H. , Kawabata N. , Teramoto M. 
Published: March 2009

AbstractEffect of pH on the aqueous phase ozonation of various organic compounds was investigated. The reaction was accelerated in alkaline media due to the formation of active hydroxyl radical by an interaction of ozone with hydroxide ion. However, in a strongly alkaline media (pH < 11.9), hydroxyl radical dissociated into less reactive oxygen ion and the efficiency of ozonation decreased. By means of the theory of gas absorption accompanied by chemical reaction, it was found that the rate of the decomposition of ozone in the presence of about 300 ppm of 1‐butanol was 5‐80 times larger than that catalyzed only by hydroxide ion in the pH range of 11‐13. Efficiency of ozonation showed that an optimum range of pH for the removal of total organic carbon was 9‐10.
Xylene isomerization by ZSM‐5 zeolite catalyst
Authors: Collins Dermot J. , Medina Roger J. , Davis Burtron H. 
Published: March 2009

AbstractThe larger pore LaY zeolite catalyst resembles homogeneous metal chloride and heterogeneous silica‐alumina acid catalysts since the results are consistent with isomerization being a series of intramolecular 1,2 shifts. On the other hand, isomerization with the smaller pore zeolite, ZSM‐5, is very different and the relative rate constants appear to be influenced by diffusion and/or shape selectivity. Disproportionation is a significant reaction with LaY but not with ZSM‐5 in the temperature range used for the present study. The small amount of trimethylbenzene formed at low conversions using ZSM‐5 is 1,2,4‐trimethylbenzene, also providing evidence of shape selectivity influencing the reaction products.
Liquefaction of wood by rapid hydropyrolysis
Authors: Beckman D. , Boocock D. G. 
Published: March 2009

AbstractPoplar wood, when heated rapidly (70‐90 s) in water to 350°C and quenched, yields oil in 55 per cent mass yield. Approximately 75 per cent of the wood carbon and hydrogen is retained in the oil. The oil contains 25 per cent oxygen (wood contains 45 per cent). Extended reaction significantly lowers yields which are the same in the presence of both nitrogen and hydrogen atomsopheres. Nickel carbonate addition lowers yields significantly. Experiments have been limited to wood particles less than 35 mesh (0.73 mm grid) but heat transfer studies are being extended to larger particles.
Steady state and transient behavior in 1‐butene reactions over bismuth molybdate
Authors: Oliveira Margarida , Portela M. Farinha , Pires Maria Joäo , Ribeiro F. Ramôa 
Published: March 2009

AbstractPulse and continuous flow techniques were used to study 1‐butene reactions in the presence of oxygen over bismuth molybdate.At 280°C and low 1‐butene partial pressures (2.1‐5.6 kPa), the activity increases with the pulse number and tends towards a constant level. At high 1‐butene partial pressures (40‐68 kPa), the activity decreases at the same conditions but tends also to stabilize. The butadiene selectivity increases and 2‐butene selectivities decrease in both cases and tend towards the selectivities observed with a continuous flow technique in steady state conditions.At 350°C, the activity has a similar behavior for low pressures of 1‐butene, but for high pressures increasing activity occurs. For such a temperature the oxidative dehydrogenation selectivity decreases and the isomerization selectivities increase with respect to the pulse number, but tend also towards the values found in steady state flow operation.Experiments at intermediate temperatures (300 and 320°C) show a coherent evolution. On other side, experimental results obtained using only 1‐butene as reactant in the absence of oxygen contributed greatly to clarification of the observed situation.The results are discussed and interpreted in the context of the reaction mechanism.
The influence of gaseous chlorine on the chemical and catalytic properties of alumina
Authors: Marczewski Marek , Derewinski Miroslaw , Malinowski Stanislaw 
Published: March 2009

AbstractThe influence of gaseous chlorine on the chemical and catalytic properties of alumina was investigated. Cl2 reacts both with surface OH groups and with surface oxygen anions possessing electron‐donating power, forming new surface sites.When such chlorine treatment is performed at a low temperature (293 K), both Lewis and Bronsted acid centres are formed. High temperature chlorination leads exclusively to Lewis acid sites. It is proposed that such Lewis sites are responsible for olefin isomerization reactions.
Investigation of a fixed‐bed pilot plant reactor by dynamic experimentation. Part 2. Simulation of reactor behaviour
Authors: Baiker Alfons , Bergougnan Michel 
Published: March 2009

AbstractData collected with forced uncorrelated sinusoidal changes of the process variables are used to simulate the behaviour of a non‐isothermal non‐adiabatic pilot plant fixed‐bed reactor. The test reaction applied is the hydrogenation of toluene to methylcyclohexane on an industrial nickel catalyst. A pseudo‐homogeneous two‐dimensional model as well as a one‐dimensional model are applied to describe the reactor behaviour. The model parameters are estimated by defining an objective function based upon residuals of the discretized differential equations instead of upon deviation from the observed variables. This procedure leads to a drastic reduction of computer expenditure. Measured and simulated temperature and concentration profiles are compared on the basis of a number of plots and fitting quality criteria. The model parameters estimated from data collected during dynamic runs are comparable to those obtained from a series of stationary experiments (23 experimental design). However, with the dynamic experiments the data necessary for modelling can be collected much more efficiently.
Simulation Mathématique de la Circulation de I'Air dans une Enceinte avec Ouvertures et Sources Chaudes Localisées
Authors: Dupuis Marc , Claude Méthot J. , Dernedde Edgar 
Published: March 2009

AbstractLa simulation mathématique de la circulation de I'air et du profil de température dans une enceinte rectangulaire avec plusieurs ouvertures et sources chaudes localisées a été réalisée sur ordinateurs. Une méthode numérique aux différenccs finies, combinée à un modéle simple de turbulence, a été utilisée pour réksoudre les équations différentielles de la conservation de la masse, de la quantité de mouvement et de I'énergie. Les calculs ont été effectués un nombre de Prandtl de 0.7, un nombre d'Archiméde d'environ 34 et le nombre de Grashof a atteint des valeurs de I'ordre de 3 × 109. Une comparaison entre les résultats numériques et ceux observés dans une maquette permet de conclure que le modtèle mathématique reproduit assez fidètlement I'écoulement de I'air et le profil de température.L'effet combiné de la convection naturelle au voisinage des sources chaudes et de la convection forcée engendre une circulation complexe dans I'enceinte. Ces conditions d'opération ont été choisies dans le but d'Ctudier les conditions de la circulation de I'air et de la température dans les salles de cuves d'électrolyse de I'aluminium.
A model on the breakdown of crude oil gel
Authors: Ananda Rao B. M. , Mahajan S. P. , Khilar Kartic C. 
Published: March 2009

AbstractA new model is proposed on the basis of the simultaneous decrease of build‐up yield stress and viscosity to describe the break down of crude oil gel. A set of two experiments conducted at different but under constant wall shear stress is required to compute the four parameters of the model. The model is verified with reported data.
Characterization of hydrodynamic parameters in rotating disc and oldshue‐rushton columns. Hydrodynamic modelling, drop size, hold‐up and flooding
Authors: Sharker S. , Phillips C. R. , Mumford C. J. 
Published: March 2009

AbstractFlooding rates, dispersed phase hold‐up, hold‐up profile and drop‐size distribution were investigated in rotating disc and Oldshue Rushton 0.10 m diameter, 18 compartment columns with toluene‐water as the liquid‐liquid system. The axial dispersed phase hold‐up and the mean drop size in both contactors varied significantly with column height. The hold‐up profiles were correlated by semi‐theoretical models.
A thermodynamic analysis of the steam ejector, uranium leach, slurry‐to‐slurry heat exchanger
Authors: Sorensen P. F. 
Published: March 2009

AbstractThe primary chemical step in the recovery of uranium oxide (U3O8) from ore in South Africa's uranium plants is thesulphuric acid teaching of slurries of the ore in water. The reaction is promoted by live steam injection to elevate temperatures to about 70°C. Up to 50 per cent of this heat can be recycled by slurry‐to‐slurry heat excange. However conventional equipment relying on conduction has proved inadequate in this duty owing to problems of solids settling. The evaporator/condenser exchanger is more appropriate. Its thermodynamics are explained and design equations developed.
Absorption of sulfur dioxide into limestone slurry in a stirred tank
Authors: Uchida S. , Ariga O. 
Published: March 2009

AbstractThe absorption rate of sulfur dioxide into limestone slurries has been observed under various experimental conditions, using a stirred tank absorber which had a plane surface. The effects of the interfacial concentration of SO2, the slurry concentration, the concentration of SO2−2 ion, and the limestone particle size on the rate have been examined.Taking the effect of SO2−2 ion on the rate into consideration, a mathematical model for SO2absorption into limestone slurries based on the film concept has been developed. The model can explain the mechanism of SO2 absorption into limestone slurries.
Modelling of non‐stationary ammonia synthesis kinetics over an iron catalyst: I. Deriving a model and estimating parameters from transient response data
Authors: Hudgins R. R. , Silveston P. L. , Chengyve Li 
Published: March 2009

AbstractThe transient reaction kinetic models of ammonia synthesis in a Berty reactor are identified and the parameters in the models are estimated from their transient responses. The basic model is founded on widely held views concerning the mechanism of ammonia formation on iron catalyst. The results obtained in this study show that a two‐site, dissociative adsorption model is acceptable while a competitive adsorption model is not.
Modelling of non‐stationary ammonia synthesis kinetics over an iron catalyst II. Modelling results of forced feed composition in periodic operation and for step‐changes
Authors: Hudgins R. R. , Silveston P. L. , Chengyue Li 
Published: March 2009

AbstractSimulation using the two‐site dissociative adsorption model given in Part 1 of this study fails to predict the improvement observed in the time‐average rate under cyclic operation even though it does recreate the observed steady‐state and transient response features following a step‐change in the feed composition. The improvement in the time‐average cycling rate is probably due to the diffusion of nitrogen into the bulk‐phase of the iron catalyst, which is a metastable nitrogen? Iron system under forced feed composition cycling. A two‐site adsorption model, modified to take account of the inventory of nitrogen in the bulk‐phase of the iron catalyst, is presented. This model predicts the improvements in ammonia production observed under periodic operation.
Particle entrainment by axisymmetric jets
Authors: Subramanian Vishwanath , Venkatram Srinivas 
Published: March 2009

AbstractThe presence of particles can enhance or reduce the entrainment of an axisymmetric air jet. Measurements of particle entrainment in the 2 phase preheated jet were made by the Ricou and Spalding (1961) technique, and the results compared with theoretical estimates. Heating the jet stream improves the entrainment.
Esterification de l'acide dichloro 2.4 phenoxyacetique role et interet des resines echangeuses d'ions
Authors: Luna M. Hernandez , Alcaraz J. , Gilot B. , Jayles C. 
Published: March 2009

AbstractThe esterification of the dichloro 2,4 phenoxy‐acetic acid occurs slowly without any catalyst. The reaction is of order 2 or 1, with respect to the acid or acohol, respectively.In the presence of an acid catalyst (acid toluene sulphonate —ion‐exchange resin), the reaction is quicker; it is of order 1 with respect to the organic acid and I with respect to the alcohol. The variation of the velocity constant recalls to mind that the mechanism is more complex, in spite of the simple representation.The ion‐exchange resins play an interesting role, because they enable to avoid a separation and they are not corrosive. It is shown, however, that the penetration into the resin is limited, even when a macroporous resin is used.
A loop three‐phase fluidized bed reactor
Authors: Herskowitz Mordechay , Merchuk Jose C. 
Published: March 2009

AbstractAn airlift three‐phase reactor in which solid particles are fluidized in the riser by the recirculating liquid was developed. Three particle types of 1.7–8.6 mm in diam., porous and nonporous, spheres and cylinders, were studied in the water–air system. Little effect of the alumina porous particles (apparent density 1.47 × 103 kg/m3) on the gas holdup and liquid superficial velocity was found. On the other hand, the heavier, nonporous ceramic particles (density 2.4 × 103 kg/m3) had a significant effect on both design parameters. The axial distribution of particles was also a function of the particle density and liquid superficial velocity.
Mechanistic consideration of paraffin, olefin and alcohol distributions in FT synthesis
Authors: Wojciechowski B. W. 
Published: March 2009

AbstractIt is shown that by assuming all chain growth in the Fischer Tropsch synthesis takes place on identical sites and that the various paraffins, olefins and alcohols produced are simply the consequence of different modes of termination, product distributions which agree with experimental observations are generated. In particular the reason for the “break” in paraffin distributions is seen to be the fact that paraffins can be formed by a termination involving either the addition of a hydrogen atom or of a CH3 to the growing chain. Since there is no comparable duality in the mode of olefin formation, olefin distributions do not show a break.
New model to calculate the choking velocity of monosize and multisize solids in vertical pneumatic transport lines
Authors: Briens C. L. , Bergougnou M. A. 
Published: March 2009

AbstractThe choking velocity is the minimum gas velocity required for the vertical dilute phase transport of a given solids flux. Experimental choking velocities obtained from the literature for both monosize and multisize particles were compared to choking velocities predicted with various published correlations. For monosize particles, Yang's correlation (1983) gave the most accurate predictions. For multisize particles, all the literature correlations gave rather poor predictions. Much more accurate predictions were obtained with a new simple physical model which assumes that an annulus forms along the pipe wall at low gas velocities. Choking then occurs when this annulus occupies approximately 25% of the total pipe cross‐sectional area.
Approche hydrodynamique d'une réaction de pulvérisation chimique
Authors: Leseur Ph. , Morancho R. , Constant G. 
Published: March 2009

AbstractLes exemples d'utilisation des aérosols générés par voie pneumatique ou ultrasonique dans l'élaboration de couches minces de composés divers (oxydes, semi‐conducteurs etc.) sur des substrats variés sont nombreux. Cependant, si les auteurs rapportent des résultats sur la composition chimique et les propriétés physiques des revêtements, ils ne font pas état d'études sur les conditions hydrodynamiques de l'écoulement de l'aérosol. Le travail présenté ici a pour but de montrer l'importance de ce paramètre et d'en faire ressortir les incidences sur la composition, la morphologie et les propriétés des couches.