Catalogue en ligne Bibliothèque Ecole Nationale Polytechnique d'Alger

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5916–5918

Titre :	Can toluene or xylene form clathrate hydrates?
Type de document :	texte imprimé
Auteurs :	Amir H. Mohammadi, Auteur ; Veronica Belandria, Auteur ; Richon, Dominique, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5916–5918
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Toluene p-xylene Clathrate hydrate formation
Résumé :	In this communication, we examine the possibility of clathrate hydrate formation of toluene and o-, m-, or p-xylene with methane as help gas. An isochoric pressure-search method was used to measure hydrate phase equilibrium boundaries. The reliability of this method is tested by generating hydrate phase equilibrium boundary data for the methane−benzene−water system and comparing them with experimental data reported in the literature. The acceptable agreements demonstrate the reliability of the technique used in this work. The new experimental data of hydrate phase equilibrium boundary for the methane−(toluene/(o/m/p)-xylene)−water systems are compared with some selected experimental data from the literature for the methane−water system to study the possibility of shifting the hydrate phase equilibrium boundary of the latter system by the presence of toluene and o-, m-, or p-xylene. It is shown that toluene and o-, m-, or p-xylene have little or almost no effect on the hydrate phase equilibrium boundary of the methane−water system.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900362v

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5907–5915

Titre :	Gas chromatography study of sewage sludge pyrolysis liquids obtained at different operational conditions in a fluidized bed
Type de document :	texte imprimé
Auteurs :	I. Fonts, Auteur ; M. Azuara, Auteur ; L. Lázaro, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5907–5915
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Sewage sludge Fluidized bed Pyrolysis liquids
Résumé :	Sewage sludge was pyrolyzed in a fluidized bed under different operational conditions with the aim of studying the influence of some operational conditions on the composition of the liquid product. These operational conditions were bed temperature (450−650 °C), inlet nitrogen rate (nitrogen flow per bed surface unit 0.057−0.090 m s−1), and solid feed rate per bed volumetric unit (0.169−0.338 kg s−1 m−3). The composition of the pyrolysis liquids obtained was analyzed by means of GC−MS and GC-FID. Different families of compounds appeared in the liquid samples obtained under the different conditions studied: aliphatic, aromatic, and polycyclic aromatic hydrocarbons; oxygen-containing aliphatic and aromatic compounds; nitrogen-containing aliphatic and aromatic compounds; steroids; chlorine-containing compounds; and sulfur-containing compounds. The composition of the liquids varied qualitatively with the temperature and quantitatively with the three operational parameters studied, with the temperature being the most influential variable. The liquids obtained at 450 °C contained oxygen-containing aliphatic compounds > steroids > aliphatic hydrocarbons > nitrogen-containing aliphatic compounds. The compounds found in the liquids obtained at 550 °C were quite similar to those obtained at 450 °C, although their proportions were different: steroids > aliphatic hydrocarbons > oxygen-containing aliphatic compounds > nitrogen-containing aromatic compounds. The composition of the liquids obtained at 650 °C varied considerably, and the most abundant compound groups were nitrogen-containing aromatic compounds > polycyclic aromatic hydrocarbons ≥ aromatic hydrocarbons.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900421a

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5901–5906

Titre :	Rigorously universal methodology of volume translation for cubic equations of state
Type de document :	texte imprimé
Auteurs :	Chorng H. Twu, Auteur ; Hui-Shan Chan, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5901–5906
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cubic equations State Complex nonpolar systems
Résumé :	To model systems typically found in hydrocarbon production problems and the chemical industry, there are three basic types of calculations are required: phase equilibria, volumetric behavior, and thermophysical properties. Since 1972, cubic equations of state (CEoS) have shown surprising capabilities in the prediction of the phase equilibria of complex nonpolar systems. However, the prediction of the liquid volumes from cubic equations of state, despite the recently important advances in CEoS/AE mixing rules, still remains the weak point of this type of equations. A rigorous, universal, but simple methodology without introducing any regressed parameters is proposed for the volume translation for all types of cubic equation of state. The proposed methodology applies to not only defined components but also petroleum fractions. The translated cubic equations of state reproduce almost exactly the liquid density over the entire temperature range from the triple point to the critical point.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900222j

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5894–5900

Titre :	Gas-liquid interfacial area in the presence of different chain length surfactants
Type de document :	texte imprimé
Auteurs :	D. Gómez-Díaz, Auteur ; J. M. Navaza, Auteur ; B. Sanjurjo, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5894–5900
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gas-liquid interfacial area Surfactant characteristics Bubble column contactor
Résumé :	The influence of surface active substances on the gas−liquid interfacial area in bubble contactors has been confirmed in previous works. The aim of the present study is analyzing the effect of the surfactant characteristics (in relation to the chain length of the hydrophobic zone) on the gas−liquid interfacial area using a bubble column as a contactor, as well as the behavior of different, commonly employed methods for the gas−liquid interfacial area determination. Two different methods for the gas−liquid area determination have been employed, and important differences between the values calculated by each method have been found. The discrepancies were assigned to different phenomena existing in this kind of systems, caused by the presence of surfactants at the gas−liquid interface. The experimental results obtained in this work under different operational conditions confirm that the chemical method contributes to higher values of interfacial area than the photographic method at low values of surfactant concentration, due to the important effect of this kind of substances on mass transfer. The effect of chain length also shows that a higher number of carbon atoms enhances the negative effect that surfactants produce upon the mass transfer.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900205q

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5885–5893

Titre :	Mathematical analysis of fluid flow and mass transfer in a cross flow tubular membrane
Type de document :	texte imprimé
Auteurs :	M. Kostoglou, Auteur ; A. J. Karabelas, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5885–5893
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cross-flow tubular membranes Mathematical analysis Integral equations
Résumé :	A mathematical analysis is presented for a simplified model of cross-flow in tubular membranes, for which a numerical treatment was recently reported. It is shown, step by step, that by using several asymptotic and analytical techniques the number of dimensionless numbers governing the problem can be reduced. Results are derived in terms of algebraic or integral equations, with accuracy comparable to those obtained from the complicated numerical solution. The analysis performed here permits an improved insight into the structure of the problem, compared to the numerical technique, and facilitates explanation of the numerically obtained results. The present approach can, in principle, be generalized for application to more complicated models of the particular process.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900056c

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5874–5884

Titre :	Numerical simulation of turbulent particle-laden flows with significant fluid to particle inertia ratio
Type de document :	texte imprimé
Auteurs :	Kunn Hadinoto, Auteur ; Jennifer Sinclair Curtis, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5874–5884
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Turbulent liquid-particle flow Microscale fluid inertia CFD model
Résumé :	Turbulent liquid−particle flow represents a particle-laden flow regime in which the microscale fluid inertia influence on the particle fluctuating motion and consequently the fluid−particle interaction is significant. The present work examines the predictive capability of a two-phase flow CFD model that is based on the kinetic theory of granular flow in simulating dilute-phase turbulent liquid−particle flows. The model predictive capability is evaluated at both the mean and fluctuating velocity levels, where the impacts of employing different drag correlations and turbulence closure models to describe the fluid−particle interactions are examined. The results suggest that the present model is capable of producing reasonably good predictions for both phases, though not yet quantitatively accurate, provided that appropriate drag correlation and the turbulence closure model are selected. In addition, the model predictive capability is also assessed for a gas−particle flow regime in which the gas to particle inertia ratio is not insignificant. For this purpose, gas−particle flow experiments involving low inertia particles are conducted using laser Doppler velocimetry technique. In this gas−particle flow regime, the results indicate that the present model can accurately predict the gas-phase turbulence though its predictive capability for the granular temperature is still lacking particularly near the pipe wall.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9000184

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5867–5873

Titre :	Application of the simplified perturbed-chain SAFT to hydrocarbon systems with new group-contribution parameters
Type de document :	texte imprimé
Auteurs :	Zhi-Yong Zeng, Auteur ; Yuan-Yuan Xu, Auteur ; Xu Hao, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5867–5873
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Group contribution method Simplified perturbed-chain Statistical associating fluid theory Hydrocarbon Genetic algorithm
Résumé :	A new group contribution (GC) method has been developed to estimate parameters of the simplified perturbed-chain statistical associating fluid theory (sPC-SAFT) for hydrocarbon. A key advantage of this method is that the binary interaction parameter between groups has been adopted in estimating the molecular parameter of pure component. Besides, parameters of all single groups are set to be the same for simplifying the model. Using genetic algorithm, twelve group interaction parameters are estimated on the basis of 71 sets of pure components of sPC-SAFT parameters. Tests and comparisons with other methods were performed in calculating the PVT and phase equilibrium data of heavy and branched hydrocarbon systems. The results show that the present GC method is better than the other predictive approaches in calculating parameters of sPC-SAFT.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8019246

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5857–5866

Titre :	Staged catalytic gasification/steam reforming of pyrolysis oil
Type de document :	texte imprimé
Auteurs :	Guus van Rossum, Auteur ; Sascha R. A. Kersten, Auteur ; Wim P.M. van Swaaij, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5857–5866
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gasification/steam reforming Pyrolysis oil¨Staged reactor MethaneC2−C3 free syngas
Résumé :	Gasification/steam reforming of pyrolysis oil was studied in a staged reactor concept, which consisted of an inert fluidized bed and a catalytic fixed bed. Methane and C2−C3 free syngas is produced at a single temperature around 800 °C at atmospheric pressure. By lowering the temperature of the fluidized bed (432−500 °C), its function is changed from a gasifier to an evaporator, and in this way the subsequent catalyst bed actually sees vaporized pyrolysis oil compounds (instead of a fuel gas), which it can more readily convert to syngas. However, the temperature of the fixed bed cannot be too low (min 700 °C) to avoid excessive carbon deposition. System calculations show that when pressurized (30 bar) pyrolysis oil gasification/reforming is considered, the catalytic exit bed temperature should be high (900−1000 °C) to reach sufficient enough methane conversion when syngas is the desired product. When only steam is added at elevated pressure, the H2/CO ratio readily increases, which is desired for hydrogen production. For other applications (e.g., Fischer−Tropsch), carbon dioxide probably has to be recycled to keep the H2/CO ratio around 2−3. The lower heating value efficiency of pyrolysis oil gasification/reforming is comparable to the lower end of the reported range of commercial methane steam reforming.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900194j

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5845–5856

Titre :	Wall effects on a sphere falling in quiescent power law fluids in cylindrical tubes
Type de document :	texte imprimé
Auteurs :	Daoyun Song, Auteur ; Rakesh K. Gupta, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5845–5856
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Quiescent power law fluids Cylindrical vessels Momentum equations Sphere
Résumé :	The effect of finite boundaries on the drag experienced by a sphere settling in quiescent power law fluids in cylindrical vessels has been investigated numerically. In particular, the momentum equations have been solved numerically over the following ranges of conditions: sphere Reynolds number, 1−100; power law index, 0.2−1; and sphere-to-tube diameter ratio, 0−0.5. Due to the backflow of the fluid caused by a falling sphere and the corresponding changes in the velocity field close to the sphere, the presence of finite boundaries leads to an increase in the drag force acting on a falling sphere thereby slowing its descent. The effect, however, is more significant at low Reynolds numbers than at high Reynolds numbers. Similarly, the additional drag due to the walls increases with the increasing degree of confinement, i.e., the sphere-to-tube diameter ratio. Overall, all else being equal, the wall effect is less severe in power law fluids than in Newtonian fluids. Furthermore, the confining walls also influence the onset of flow separation and subsequently the size of the recirculation region. The present numerical predictions are consistent with the experimental results available in the literature.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900176y

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5833–5844

Titre :	Viscosity modeling and prediction of aqueous mixed electrolyte solutions
Type de document :	texte imprimé
Auteurs :	Mohammed Taghi Zafarani-Moattar, Auteur ; Roghayeh Majdan-Cegincara, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5833–5844
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Viscosity Aqueous mixed electrolyte solution Eyring’s absolute rate theory Electrolyte NRTL Wilson theories
Résumé :	Viscosity values of the ternary aqueous mixed electrolyte solutions have been correlated with models based on the Eyring’s absolute rate theory and the electrolyte NRTL, modified NRTL, and Wilson theories for calculating the excess Gibbs energy of activation of the viscous flow. Utilization of the mixing rule assumption in the viscosity parameter of Einstein’s relation has made it possible to use the binary parameters of the local composition models in extending of these equations to the ternary electrolyte systems. Performance of the investigated models in the correlation of the viscosity data of the ternary mixed electrolytes + H2O systems is good. A new semiempirical equation has also satisfactorily been used to correlate the viscosity of the ternary aqueous multielectrolyte solutions. The quality fitting of this semiempirical equation is much better than the aforementioned local composition models. A simple exponential equation with consideration of the temperature dependency has also been used to correlate the viscosity values of solute. Usage of calculated solute viscosity in the suitable mixing rule made it possible to predict the viscosity of aqueous mixed electrolyte solutions. The agreement between the predicted and experimental viscosity values of aqueous multielectrolyte solutions is excellent over the entire composition and temperature range.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801933u

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5824–5832

Titre :	Investigation into bubble size distribution and transient evolution in the sparger region of gas-liquid external loop airlift reactors
Type de document :	texte imprimé
Auteurs :	Changqing Cao, Auteur ; Liangliang Zhao, Auteur ; Dongyan Xu, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5824–5832
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gas sparger Bubble size distribution Gas-liquid external loop airlift reactors
Résumé :	It is well-known that the gas sparger can play an important role on the transient evolution of bubbles and bubble size distribution (BSD) in gas−liquid external loop airlift reactors (EL-ALRs). Therefore, the main subject of the present work was to study the influence of sparger design and process parameters on the transient evolution of bubbles and bubble size distribution (BSD) in the sparger region of the considered EL-ALRs. For this purpose, both detailed measurements and prediction of the size of bubbles produced at the sparger were carried out in EL-ALRs with different size and sparger structure parameters. The unique set of BSD curves were obtained by analyzing a large amount of bubbles with a measurement based on an image analysis technique. Additionally, Colella’s model of BSD evolution in bubble columns was further developed by implementing a detailed physical model for predicting the initial BSD at the sparger applied to gas−liquid EL-ALRs where the model input is only based on design/process parameters. A validation of the model was carried out using data from gas−liquid EL-ALRs with different size and sparger design parameters. In order to provide more deep insight for transient evolution of bubbles at the local scale in the sparger region, the computational fluid dynamics (CFD) code Fluent 6.2 was used. The transient evolution of bubbles was simulated in the sparger region of gas−liquid EL-ALR. The simulating results of bubble size are in good agreement at the lower gas velocity with the experimental data in the sparger regions of TU-A and TU-B. With increasing gas flow rate, the difference between simulations and experimental values for bubble size increases. The simulations underestimate bubble size at high gas flow rate.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801700s

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5816–5823

Titre :	Novel single stripper with side-draw to Remove Ammonia and sour gas simultaneously for coal-gasification wastewater treatment and the industrial implementation
Type de document :	texte imprimé
Auteurs :	Dachun Feng, Auteur ; Zhenjiang Yu, Auteur ; Yun Chen, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5816–5823
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Wastewater Coal-gasification process Carbon dioxide Ammonia
Résumé :	A large amount of wastewater is produced in the Lurgi coal-gasification process with the complex compounds carbon dioxide, ammonia, phenol, etc., which cause a serious environmental problem. Most of the known pretreatment techniques do not yield sufficient performance for phenol removal, which hampers the functions of the subsequent biochemical treatment process. In this paper, a novel stripper operated at elevated pressure is designed to improve the pretreatment process. In this technology, two noticeable improvements were established. First, the carbon dioxide and ammonia were removed simultaneously in a single striper where sour gas (mainly carbon dioxide) is removed from the tower top and the ammonia vapor is drawn from the side and recovered by partial condensation. Second, the ammonia is removed before the phenol recovery to reduce the pH value of the subsequent extraction units, so as the phenol removal performance of the extraction is greatly improved. To ensure the operational efficiency, some key operational parameters are analyzed and optimized though simulation. It is shown that when the top temperature is kept at 40 °C and the weight ratio of the side draw to the feed is above 9%, the elevated pressures can ensure the removal efficiency of NH3 and carbon dioxide and the desired purified water as the bottom product of the unit is obtained. A real industrial application demonstrates the attractiveness of the new technique: it removes 99.9% CO2 and 99.6% ammonia, compared to known techniques which remove 66.5% and 94.4%, respectively. As a result, the pH value of the wastewater is reduced from above 9 to below 7. This ensures that the phenol removal ratio is above 93% in the following extraction units. The operating cost is lower than that of known techniques, and the operation is simplified.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9002987

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5808–5815

Titre :	Study on multiphase flow and mixing in semidry flue gas desulfurization with a multifluid alkaline spray generator using particle image velocimetry
Type de document :	texte imprimé
Auteurs :	Yuegui Zhou, Auteur ; Dongfu Wang, Auteur ; Mingchuan Zhang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5808–5815
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Particle image velocimetry Gas-droplet-solid multiphase flow Gas desulfurization process Multifluid alkaline spray generator
Résumé :	Particle image velocimetry (PIV) technique was used to measure the velocity fields of gas−droplet−solid multiphase flow in the experimental setup of a novel semidry flue gas desulfurization process with a multifluid alkaline spray generator. The flow structure, mixing characteristic, and interphase interaction of gas−droplet−solid multiphase flow were investigated both in the confined alkaline spray generator and in the duct bent pipe section. The results show that sorbent particles in the confined alkaline spray generator are entrained into the spray core zone by a high-speed spray jet and most of the sorbent particles can be effectively humidified by spray water fine droplets to form aqueous lime slurry droplets. Moreover, a minimum amount of air stream in the generator is necessary to achieve higher collision humidification efficiency between sorbent particles and spray water droplets and to prevent the possible deposition of fine droplets on the wall. The appropriate penetration length of the slurry droplets from the generator can make uniform mixing between the formed slurry droplets and main air stream in the duct bent pipe section, which is beneficial to improving sulfur dioxide removal efficiency and to preventing the deposition of droplets on the wall.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8019714

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5802–5807

Titre :	CO2 removal from contaminated natural gas mixtures by hydrate formation
Type de document :	texte imprimé
Auteurs :	Mark van Denderen, Auteur ; Erik Ineke, Auteur ; Michael Golombok, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5802–5807
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gas hydrates Methane/CO2 mixtures
Résumé :	We analyzed the formation rates of gas hydrates from methane/CO2 mixtures associated with contaminated well gas streams, which results in a methane-enriched gas product. The initial pressure affects both the final clean gas composition and the time taken to achieve it. Although promoters have been described, we note that this term often refers to interstitial materials that stabilize equilibrium hydrate structures rather than classical chemical rate promoters (i.e., catalysts). We also show that previously reported hydrate rate improvers are irrelevant for commercial purposes because they merely overcome inadequate mixing systems. We identify the key process requiring rate acceleration and show the potential for reducing the time for this process to make selective CO2 hydrate formation commercially attractive. We also examine the effect of salinity on the selective formation of CO2 hydrates. The phase boundary pressures increase with increasing salt concentration, and the rate of formation decreases. Formation times are on the order of 1 h, so catalysts are required to make this process commercially viable.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8017065

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5794–5801

Titre :	The preparation and characterization of hydrotalcite thin films
Type de document :	texte imprimé
Auteurs :	Tae Wook Kim, Auteur ; Muhammad Sahimi, Auteur ; Theodore T. Tsotsis, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5794–5801
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	CO2-selective inorganic membranes Thin films Hydrotalcites
Résumé :	Owing to the recent focus on reducing CO2 emissions, the preparation and characterization of CO2-selective inorganic membranes and thin films has received considerable attention. Hydrotalcites (HT) are, potentially, good materials for preparing CO2-selective inorganic membranes and films due to their high CO2 adsorption capacity at elevated temperatures and their good thermal stability. The purpose of this study, therefore, was to prepare CO2-selective HT films and to understand their transport characteristics. A vacuum-suction method was used for the synthesis of the HT films, and their properties were characterized using both single and mixed-gas permeation tests, as well as by nitrogen adsorption and by SEM and XRD. The HT films are microporous, as indicated by both the adsorption data, as well as by the fact that the ideal selectivities of pairs of inert gases (e.g., He, N2, and Ar) through the membrane are higher than the Knudsen values. However, the as-prepared materials contain a substantial fraction of voids and pinholes. Plugging these voids and pinholes using a silicone coating results in CO2-permselective films, which exhibit CO2/N2 and CO2/He ideal separation factors of 34.4 and 12.4, respectively.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900371r

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5789–5793

Titre :	Ce0.8Sm0.2O2−δ−La0.8Sr0.2MnO3−δ dual-phase omposite hollow fiber membrane for oxygen separation
Type de document :	texte imprimé
Auteurs :	Wei Li, Auteur ; Ting-Fang Tian, Auteur ; Feng-Yuan Shi, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5789–5793
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Dense ceramic oxygen separation membrane Cryogenic distillation process
Résumé :	The dense ceramic oxygen separation membrane holds promise to reduce the oxygen production cost significantly over the current mature cryogenic distillation process. Preparation of membranes in hollow fiber geometry is expected to lead to a remarkable increase in the oxygen production capacity of the membrane unit. Gas-tight Ce0.8Sm0.2O2−δ−La0.8Sr0.2MnO3−δ dual-phase composite hollow fibers were prepared by a phase-inversion/sintering technique. A stable oxygen permeation rate of 3.2 × 10−7 mol·cm−2·s−1 was measured under air/He gradient at 950 °C, and 3.0 × 10−7 mol·cm−2·s−1 was found under air/CO2 gradient. It was also found that oxygen permeation through the hollow fiber can be well-described by the Wagner equation and assuming that the gas flow in the core of the fiber conforms to the plug flow model.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9002624

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5779–5788

Titre :	Design and cost evaluation of a separation process for a multicomponent mixture using dense CO2
Type de document :	texte imprimé
Auteurs :	Laura Álvarez, Auteur ; Angel Martin, Auteur ; Germán Sanjuán, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5779–5788
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Multicomponent mixture Dense CO2 Enzymatic reactor
Résumé :	Simulations done on the separation of a multicomponent mixture exiting an enzymatic reactor using dense CO2 as solvent are presented. The enzymatic reaction was carried out in the liquid phase although the CO2 was introduced in supercritical state (80 bar and 40 °C). The purpose was to obtain α-methylbenzyl acetate, a fruity and floral aroma used in the food and cosmetic industries, from the corresponding alcohol and acetic anhydride. The separation of the effluent, consisting of five components (two products, the nonconverted reactants, and the solvent) was done in a series of countercurrent extraction columns where, again, CO2 was used as solvent. It was introduced at relatively low pressure (20 bar) since higher values lead to solubilization of all the components. The influence of the S/F ratio, the feed inlet position, the column dimensions and the use of reflux was analyzed for the separation of the main product with a model available from literature. The diameter of the column was estimated to avoid flooding. Then, the flow sheet of the integrated reaction−separation process with CO2 recycling was presented and discussed. Using an pressure−enthalpy diagram, the energy costs were deduced. The fixed costs were also guessed from previous experience. Using both items, the economical evaluation of the process was performed for a 5-d operation corresponding to the annual production of the aroma. The analysis showed that the process could be feasible after a fine optimization of the enzyme lifetime and reaction efficiency since the downstream separation was inexpensive. In order to make the process effectively profitable, applications would have to be found for the rest of the year (e.g., on the synthesis of other esters).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801914q

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5767–5778

Titre :	A computationally efficient scheme for model predictive control of nonlinear hybrid systems using generalized outer approximation
Type de document :	texte imprimé
Auteurs :	Naresh N. Nandola, Auteur ; Sharad Bhartiya, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5767–5778
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Mixed integer nonlinear programs Model predictive control Nonlinear hybrid systems
Résumé :	This paper presents an efficient optimization algorithm suitable for online solution of mixed integer nonlinear programs resulting from the model predictive control (MPC) of nonlinear hybrid systems. The system model is based on a recently proposed multiple partially linear (MPL) modeling scheme. The algorithm, based on generalized outer approximation (GOA), uses structural information of the canonical MPL framework as well as analytical expressions for the objective function and constraints of a relatively simple primal problem as well as the master problem. Specifically, the primal problem of GOA reduces to a quadratic program when MPL models are used in MPC. Computational efficiency of the algorithm over the branch and bound strategy is demonstrated using a simulated benchmark three-spherical tank system and a hydraulic process plant.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801384y#fn1

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5742–5766

Titre :	Computational comparison of piecewise-linear relaxations for pooling problems
Type de document :	texte imprimé
Auteurs :	Chrysanthos E. Gounaris, Auteur ; Ruth Misener, Auteur ; Christodoulos A. Floudas, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5742–5766
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Pooling problem Relaxation tightness Global optimization algorithm Piecewise linearization scheme
Résumé :	This work discusses alternative relaxation schemes for the pooling problem, a theoretically and practically interesting optimization problem. The problem nonconvexities appear in the form of bilinear terms and can be addressed with the relaxation technique based on the bilinear convex and concave envelopes. We explore ways to improve the relaxation tightness, and thus the efficiency of a global optimization algorithm, by employing a piecewise linearization scheme that partitions the original domain of the variables involved and applies the principles of bilinear relaxation for each one of the resulting subdomains. We employ 15 different piecewise relaxation schemes with mixed-integer representations and conduct a comprehensive computational comparison study over a collection of benchmark pooling problems. For each case, various partitioning variants can be envisioned, cumulatively accounting for a total of 56 700 relaxations. The results demonstrate that some of the schemes are clearly superior to their counterparts and should, therefore, be preferred in the optimization of pooling processes.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8016048

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5731–5741

Titre :	Soft chemical analyzer development using adaptive least-squares support vector regression with selective pruning and variable moving window size
Type de document :	texte imprimé
Auteurs :	Yi Liu, Auteur ; Naiping Hu, Auteur ; Haiqing Wang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5731–5741
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Soft analyzers Adaptive least-squares support vector regression algorithm Nonlinear multi-input-multi-output process modeling Framework Time-varying dynamics
Résumé :	Soft analyzers have been increasingly accepted as an alternative to physical ones in the chemical industry to infer and improve the product quality. In this study, an adaptive least-squares support vector regression (ALSSVR) algorithm is proposed for the issue of nonlinear multi-input−multi-output process modeling and applied to soft chemical analyzer development. The ALSSVR algorithm adopts the moving window scheme and a two-stage recursive learning framework to trace the time-varying dynamics of a process. The useless sample (i.e., a node of analyzer model), while not the oldest one, is selectively deleted from the model topology, using the fast leave-one-out cross-validation criterion. Consequently, the updated model can exhibit good generalization ability and trace the process characteristics effectively. Besides, a variable moving window is proposed, so its size can be adaptively adjusted, relative to process changes. The ALSSVR-based soft analyzer is then applied to an industrial fluidized catalytic cracking unit to predict its three key product yields. The obtained results show that the presented ALSSVR method is superior to conventional recursive least-squares support vector regression (RLSSVR) approaches. The maximal root-mean-square error (RMSE) of all product yields is <1.5 and the maximal relative prediction error (RE) is ∼7%, which can be acceptable in industrial practice for the intended objective of soft analyzers.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8012709

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5719–5730

Titre :	A comprehensive evaluation of PID, cascade, model-predictive, and RTDA controllers for regulation of hypnosis
Type de document :	texte imprimé
Auteurs :	Yelneedi Sreenivas, Auteur ; Tian Woon Yeng, Auteur ; G.P. Rangaiah, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5719–5730
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Anesthesia Proportional-integral-derivative controller Closed-loop systems
Résumé :	Although manual control of anesthesia is still the dominant practice during surgery, an increasing number of studies have been conducted to investigate the possibility of automating this procedure. Several clinical studies that compare closed-loop to manual anesthesia control performance have been reported. These studies used proportional−integral−derivative (PID) controllers, as well as model-based controllers. However, there is a need for a comprehensive evaluation of closed-loop systems, to establish their safety, reliability, and efficacy for anesthesia regulation. This requires a detailed evaluation of promising and/or recent controllers for a range of patients and conditions via simulation. The present study investigates the performance of single-loop PID, cascade, model-predictive, and RTDA (Robustness, set point Tracking, Disturbance rejection, Aggressiveness) controllers for closed-loop regulation of hypnosis using isoflurane with bispectral index (BIS) as the controlled variable. Extensive simulations are performed using a model that simulates patient responses to the drug, surgical stimuli, and unexpected surgical events. Results of this comprehensive evaluation show that model-predictive and RTDA controllers provide better regulation of BIS, compared to the other controllers tested.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800927u

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5708–5718

Titre :	Comparative analysis of some approaches to the autotuning of cascade controls
Type de document :	texte imprimé
Auteurs :	Alberto Leva, Auteur ; Alberto Marinelli, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5708–5718
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cascade controls Autotuning
Résumé :	Some approaches to the autotuning of cascade controls are comparatively analyzed on the basis of a conveniently characterized test batch. The reported analysis results provide some remarks and possible guidelines for the design of cascade autotuners. Peculiar to the presented simulation study is that the “identification experiment” is considered as an integral part of the autotuning procedure—an aspect of the overall matter that is seldom addressed in the literature.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801139n

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5696–5707

Titre :	Use of subcritical CO2 for production of ultrafine particles by pressure reduction of gas-expanded organic liquids
Type de document :	texte imprimé
Auteurs :	Sameer V. Dalvi, Auteur ; Mamata Mukhopadhyay, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5696–5707
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Subcritical carbon dioxide Ultrafine solid particles Drastic reduction
Résumé :	In this paper we illustrate the use of subcritical carbon dioxide to precipitate ultrafine solid particles. The process has been developed to attain rapid, high, and uniform supersaturation by drastic reduction of the solution temperature and is named PPRGEL (precipitation by pressure reduction of gas-expanded liquids). Rapid pressure reduction over a CO2-expanded liquid solution from 40−70 to 1 bar at 303 K reduces the solution temperature by 30−80 K in a very short span of time (0.5−1.5 min) and facilitates precipitation of ultrafine particles. The process performance has been evaluated for particle production of cholesterol from 100 mL of its acetone and ethanol solutions (5−10 mg/mL) at 40–70 bar and 303 K using a 1 L high-pressure vessel. Particles with a size range of 200 nm to 7 μm and morphologies of near-spherical to needles have been produced with a change in operating conditions.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900132r

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5691–5695

Titre :	Catalyst-free, one-step synthesis of olivary-shaped carbon from olive oil
Type de document :	texte imprimé
Auteurs :	Pol, Vilas G., Auteur ; Jose M. Calderon-Moreno, Auteur ; P. Thiyagarajan, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5691–5695
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Olivary-shaped carbon particles Closed reactor Olive oil Autogenic pressure
Résumé :	High-purity olivary-shaped carbon particles with a diameter of ∼1.5 μm at the middle and a length of ∼3 μm were synthesized by the thermolysis [700 °C] of olive oil under its autogenic pressure in a closed reactor. We employed in situ mass spectrometry to monitor the volatile gases responsible for the autogenic pressure generated during the thermolysis of olive oil in the closed reactor and also measured the autogenic pressure as a function of temperature. The olivary shape of as-prepared microcarbon is verified by scanning electron microscopy and the composition by C,H,N−S and energy-dispersive X-ray analysis. The structural information is determined by powder X-ray diffraction and Raman spectroscopy, while the magnetic properties are determined by electron paramagnetic resonance. We propose a putative mechanism for their formation by using all the complementary data.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900095v

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5686–5690

Titre :	Rapid, facile synthesis of silver nanostructure using hydrolyzable tannin
Type de document :	texte imprimé
Auteurs :	Emrah Bulut, Auteur ; Mahmut Özacar, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5686–5690
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Silver nanoparticles Distinct synthesis process Facial synthesis process Aqueous medium Tannin
Résumé :	A facial and distinct synthesis process of silver nanoparticles stabilized by tannin in aqueous medium is reported. Silver nitrate is solubilized in water as the source of silver ions, and tannin is solubilized in water as both a reducing agent and stabilizer matter. Due to hydroxyl groups and the dendritic macrostructure of tannin, it was used as both a reducer and stabilizer. The concentrations of tannin and of AgNO3 solution were changed to observe variation in particle size. However the role of the dendritic tannin molecule in forming silver nanoparticles was explained, and changes of the tannin molecule due to the redox reaction were determined by Fourier transform infrared (FTIR) measurements. The structure of synthesized silver nanoparticles has been investigated through scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis revealed the face-centered cubic (fcc) geometry of silver nanoparticles. Also a UV−vis spectrophotometer was used to obtain the absorption spectrum of silver nanoparticles.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801779f

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5679–5685

Titre :	Selective copper(II) sorption behavior of surface-imprinted core-shell-type polymethacrylate microspheres
Type de document :	texte imprimé
Auteurs :	Hoang Anh Dam, Auteur ; Dukjoon Kim, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5679–5685
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Metal ion-imprinted polymer microspheres Core−shell-type Polystyrene core Ethylene glycol dimethacrylate Copper methacrylates
Résumé :	Core−shell-type metal ion-imprinted polymer microspheres (MIIPs) were prepared. The shell layer was established on the surface of the polystyrene core via novel precipitation polymerization of ethylene glycol dimethacrylate (EGDMA) and copper methacrylates (Cu(MAA)2). The prepared microparticles showed a very narrow size distribution from 2.5 to 3.2 μm, depending on the amount of the dispersing medium. The size, structure, and zeta potential of the MIIP particles were investigated using scanning electron microscopy (SEM) and a zeta meter. The MIIPs showed an excellent selective separation capability for the target Cu(II) ion over other ions possessing the same ionic valence number, such as Ni(II), Cd(II), and Mg(II). The elapsed time to adsorption equilibrium was very short, and the adsorption capacity increased with pH up to the saturation of 70% at pH 5.6. The MIIP microspheres exhibited a much higher separation capacity and selectivity for the target imprinted ion than non-MIIP.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801321d

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5671–5678

Titre :	Powder micronization using a CO2 supercritical antisolvent type process : comparison of different introduction devices
Type de document :	texte imprimé
Auteurs :	Olivier Boutin, Auteur ; Thomas Petit-Gas, Auteur ; Elisabeth Badens, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5671–5678
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	CO2 antisolvent Recrystallization processes Impinging jets Concentric tube antisolvent reactor
Résumé :	Many recrystallization processes in supercritical medium utilize CO2 as antisolvent. This work presents two introduction devices based on the principle of the supercritical antisolvent process: the impinging jets and the concentric tube antisolvent reactor. Those two processes are very simple to develop and allow improving the mixing between the two phases. Some experiments have been conducted for the impinging jets using L-polylactic acid at 10 MPa and 308 K giving spherical particles with average diameter varying from 1.4 to 2.3 μm. For the concentric tube antisolvent reactor, griseofulvin was tested at 10 MPa and temperatures between 308 and 323 K providing needles with lengths between 25 and 50 μm. These results combined with previous ones allow comparing these introduction devices with the classical supercritical antisolvent (SAS) process, demonstrating the following improvements: (i) reduction of particle size, (ii) increase in initial solute concentration, and (iii) process intensification.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8017803

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5666–5670

Titre :	Preferential oxidation of CO in H2 stream on Au/TiO2 catalysts : effect of preparation method
Type de document :	texte imprimé
Auteurs :	Palanivelu Sangeetha, Auteur ; Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5666–5670
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Au/TiO2 catalysts Deposition-precipitation methods Inductively coupled plasma-mass spectrometry X-ray diffraction Transmission electron microscopy X-ray photoelectron spectroscopy
Résumé :	A series of Au/TiO2 catalysts were prepared by either photodeposition or deposition−precipitation methods. The catalysts were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of these catalysts was investigated by preferential oxidation of carbon monoxide in a hydrogen stream. A high gold dispersion and narrow size distribution was obtained for Au/TiO2 catalysts prepared by both photodeposition or deposition−precipitation methods. The photodeposition method facilitates the preparation of gold particles as small as 1.5 nm on the support, whereas in the deposition−precipitation method, the gold particles were found to be around 2−3 nm. The catalyst prepared by the photodeposition method showed higher CO conversion and CO selectivity than those prepared by the deposition−precipitation method. The selectivity of CO reacting with O2 decreased with increasing reaction temperature due to H2 competing with CO at high temperatures. Au/TiO2 catalysts prepared by the photodeposition method showed relatively higher CO selectivity below 65 °C when compared with the deposition−precipitation method. The differences in activity could be attributed to the difference in chemical state of gold particles and the particle size of gold. The catalyst prepared by photodeposition had a smaller particle size (1.5 nm). It had higher CO conversion at low temperature (<50 °C). However, the CO conversion and CO selectivity is low between 50 and 100 °C.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900403s

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5656–5665

Titre :	Introduction of a breakage probability function in the hydrocracking reactor model
Type de document :	texte imprimé
Auteurs :	Simone Gamba, Auteur ; Laura A. Pellegrini, Auteur ; Vincenzo Calemma, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5656–5665
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	C-C bonds Fischer-Tropsch waxes Reactor model Hydrocracking
Résumé :	This paper shows how a breakage probability function for the C−C bonds, elaborated from experimental evidence reported in literature, is introduced in the reactor model for the hydrocracking of Fischer−Tropsch waxes. The results demonstrate a better response to the variation of the operating conditions (especially as concerns temperature) and show product distributions closer to the experimental ones than those predicted by the previous model [Pellegrini, L. A. et al. Chem. Eng. Sci. 2008, 63, 4285]. The agreement with the experimental data has also been enhanced introducing a dependence on temperature (in addition to the dependence on the number of carbon atoms) in the expressions for the Langmuir constants and giving the equilibrium constants for isomerization reactions a new function derived from a thermodynamic study.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8019455

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5642–5655

Titre :	Selective homogeneous oxidation system for producing hydroperoxides concentrate : kinetics of catalytic oxidation of gas oils
Type de document :	texte imprimé
Auteurs :	Syed Mumtaz Danish Naqvi, Auteur ; Fasihullah Khan, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5642–5655
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Selective homogeneous oxidation system Hydroperoxides Gas oil
Résumé :	A selective and mild (55 °C and 50 psig) homogeneous oxidation system has been described to produce hydroperoxides from a narrow cut made from typical gas oil. During this process oil, dissolved in wet acetic acid, is treated with air in the presence of the redox couple Co(III)/Co(II) (partially oxidized catalyst, POC). A straightforward route to POC consists of oxidizing Co(II) in wet acetic acid with calculated aqueous potassium chlorate. Initiation is the manifestation of the potent oxidizing ability of Co(III) toward generating alkyl radicals from hydrocarbons in the oil. Classical propagation then leads to assorted hydroperoxides, simultaneously decomposed by POC. Kinetics of the simultaneous formation and decomposition of hydroperoxides, under varying sets of process and composition variables, was studied in an isothermal, mechanically agitated, semibatch reactor, operating in the pure kinetic regime. A unique kinetic model, based on a rare irreversible consecutive reaction network (pseudo-first-order formation of hydroperoxides followed by their second-order decomposition), has been found to reasonably describe the kinetic data (R2 = 0.9214). This kinetic model allowed the evaluation of the formation and decomposition rate constants that permitted the estimation of conversion of oil and selectivity to hydroperoxides. On average 15.12 ± 3.23% conversion was achieved in 9.3 ± 4.0 min with 99.86 ± 0.23, 92.88 ± 7.95, and 28.77 ± 11.67% selectivities for 0.10, 1.00, and 10.0% conversions, respectively.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900364w

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5633–5641

Titre :	Kinetics of carbon monoxide oxidation over CuO supported on nanosized CeO2
Type de document :	texte imprimé
Auteurs :	Jose L. Ayastuy, Auteur ; Anita Gurbani, Auteur ; María P. González-Marcos, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5633–5641
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	CuO/CeO2 catalyst Nanosized ceria CO oxidation
Résumé :	A CuO/CeO2 catalyst prepared by incipient wetness impregnation (7 wt % Cu) with well-dispersed CuO on nanosized ceria, has been used to obtain a kinetic expression for CO oxidation, including estimation of kinetic parameters, in the absence of CO2, H2O, or H2 in the feed stream. Experimental data were checked to be collected in the kinetic regime, in the absence of external and intraparticle mass and heat transfer, and in a wide range of experimental conditions—with CO partial pressure ranging from 0.0015 to 0.0125 atm (that is, including those usually found in PROX reactors) and λ values between 0.35 and 13.3— and were fitted to different rate expressions (power-law and mechanistic) by using a genetic algorithm. Although a power-law rate equation satisfactorily fits the experimental data, it is limited to the experimental range of operation conditions. Further discrimination among mechanistic models indicates that an expression proposed by Liu and Flytzani−Stephanopoulos (Chem. Eng. J. 1996, 64, 283), with a partial reaction order of 0.08 with respect to oxygen, is the most statistically significant, almost indistinguishable from the expression proposed by Mars−Van Krevelen (Spec. Suppl. Chem. Eng. Sci. 1954, 3, 41).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9001603

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5624–5632

Titre :	Investigation into the behavior of reductive decomposition of calcium sulfate by carbon monoxide in chemical-looping combustion
Type de document :	texte imprimé
Auteurs :	Hongjing Tian, Auteur ; Qingjie Guo, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5624–5632
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Chemical-looping combustion Nitrogen oxide formation Calcium sulfate
Résumé :	Chemical-looping combustion is a promising technology with no contact between fuel and combustion air, featuring the inherent separation of CO2 and avoidance of nitrogen oxide formation. To some metal oxide oxygen carriers, the high costs and positive hazard to living environment inhibit the application of chemical-looping combustion systems in large scale. In this work, we investigate the possibility of using calcium sulfate as oxygen carrier. The release amount of SO2 was not only due to the reacting temperature but also affected by the partial pressure of CO in the reaction. If the partial pressure of CO in the atmosphere is big enough, the release amount of SO2 or the occurrence of side reactions can be eliminated fully even if the temperature is as high as 1000 °C. The reactivity behavior of the reduction of CaSO4 by CO in the heating process is also studied. The values of activation energy, frequency factor, and linear factor corresponding to five different heating rates are calculated using an accurate kinetics integral expression and a temperature integral approximation with high precision. The most probable mechanism function in the decomposition process is characterized by G(α) = [−ln(1 − α)]1/2.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900089m

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5610–5623

Titre :	Batch reactors for hydrogen production : theoretical analysis and experimental characterization
Type de document :	texte imprimé
Auteurs :	David L. Damm, Auteur ; Andrei G. Fedorov, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5610–5623
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Transient batch-style reactors Hydrogen production
Résumé :	Transient batch-style reactors (CHAMP) were recently shown to be an attractive alternative to continuous-flow reactors for hydrogen production in portable and distributed applications, and idealized kinetic reactor models were used to analyze the performance characteristics. Here, we expand this analysis with the development of a comprehensive batch reactor model which accounts for the effects of mass transport limitations on reactor performance. The relationships between system design parameters and the rate-limiting processes that govern reactor output are identified and mapped out. Additionally, two modes of operation of either constant-volume or constant-pressure reactors are investigated. In constant-volume mode, the residence time is precisely controlled to reach a desired operating state in a trade-off between efficiency and power output without compressing the content of the reaction chamber. In constant-pressure mode, the volume of the reactor is actively reduced by moving a piston along the trajectory that maintains the operating pressure at its maximum allowable value thus enhancing the reactor throughput. Complementary to the theoretical analysis, we report on the development and experimental characterization of two test reactors. The first reactor is a constant-volume batch reactor (no permeable membrane) and provides data on the transient evolution of species concentrations within the reaction chamber. The second reactor incorporates a hydrogen permeable membrane and allows for both constant-volume and variable-volume operation. The experimental data obtained using these reactors are used to validate the predictive value of the reactor model developed in the present study.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8015126

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5604–5609

Titre :	Oxidative degradation of organophosphorous pesticides by -nhalamine fabrics
Type de document :	texte imprimé
Auteurs :	Xin Fei, Auteur ; Gang Sun, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5604–5609
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Cotton Cotton/polyester fabrics Halamine structures Organophosphorus pesticides
Résumé :	Cotton and cotton/polyester fabrics containing halamine structures were able to react with certain organophosphorus pesticides upon contact. The reaction occurred at thione group in methyl parathion and malathion, and reaction products were oxon compounds. The fabric containing imide and amide halamine structures were able to oxidize 90% of methyl parathion in less than 2 h of contact time under room temperature, while the amine halamine structure needed longer time to reach the same level of oxidation. The reaction was endothermic, and the oxidation rate was in first order to the concentrations of the pesticides.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801254u

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5598–5603

Titre :	Effect of preparation processes on catalytic performance of PtSnNa/ZSM-5 for propane dehydrogenation
Type de document :	texte imprimé
Auteurs :	Hui Liu, Auteur ; Zhou Yuming, Auteur ; Yiwei Zhang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5598–5603
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	PtSnNa/ZSM-5 catalyst Propane dehydrogenation BET surface area measurement
Résumé :	The effect of different preparation processes (impregnation and agglomeration) on the performance and properties of PtSnNa/ZSM-5 catalyst for propane dehydrogenation was studied. Some methods such as BET surface area measurement, catalyst particle mechanical strength, temperature-programmed desoption of ammonia (TPDA), Solid-state 27Al MAS NMR spectroscopy and temperature-programmed reduction of hydrogen (H2-TPR) were used to characterize the catalysts. The channel of ZSM-5 was hardly blocked after adding the binder despite the sequence of agglomeration and impregnation. Meanwhile the Pt metal dispersion on the preimpregnating catalyst with 5 wt % binder was the highest and the acidity was the weakest. The experimental results of propane dehydrogenation reaction showed that the preimpregnating catalyst with 5 wt % binder indicated the optimum reactivity in three catalysts. Therefore, the preimpregnating method in the case of adding a small amount binder was the optimal preparation method of the catalyst, which could replace the conventional preagglomerating method. Finally, a model for the effect of preparation processes on catalytic performance of PtSnNa/ZSM-5 catalyst was proposed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900311j

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5590–5597

Titre :	Synthesis and controlled release properties of prednisone intercalated Mg−Al layered double hydroxide composite
Type de document :	texte imprimé
Auteurs :	Fusu Li, Auteur ; Lan Jin, Auteur ; Jingbin Han, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5590–5597
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Drug-inorganic composite Prednisone-cholate ion micelles Mg-Al layered double hydroxide X-ray diffraction Fourier transform infrared UV-vis absorption spectroscopy
Résumé :	A drug−inorganic composite involving prednisone−cholate ion micelles intercalated Mg−Al layered double hydroxide (LDH) has been assembled by a coprecipitation method. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and UV−vis absorption spectroscopy indicate a successful intercalation of prednisone-containing micelles into galleries of the LDH matrix. The in vitro drug release studies show that no burst release phenomenon was observed at the beginning of release tests, and the pH value imposes very little influence on the release performance of prednisone in the studied pH range 4.8−7.6. It is, therefore, concluded that the MgAl-LDH can be used as an excellent inorganic drug carrier for prednisone in a wide range of pH values. Four kinetic models (first-order equation, Higuchi equation, Bhaskas equation, and Ritger−Peppas equation) were chosen to study the release kinetics of prednisone from the LDH carrier, and it was found that this process can be described by the Ritger−Peppas equation satisfactorily based on a directing Excel-based solver (DEBS). Moreover, the mechanism for drug release was also discussed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900043r

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5584–5589

Titre :	Sphalerite flotation using an arylhydroxamic acid collector : improving grade while using a reduced amount of copper sulfate for activation
Type de document :	texte imprimé
Auteurs :	Daniel Hamilton, Auteur ; Ramanathan Natarajan, Auteur ; Inderjit Nirdosh, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5584–5589
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	N-Hydrocinnamoyl-N-phenylhydroxylamine Float sphalerite Copper sulfate activation
Résumé :	N-Hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) was determined to float sphalerite without copper sulfate activation. However, the concomitant flotation of sulfidic (pyrite) and nonsulfidic gangue (silica) minerals significantly reduced the grade of the float concentrate. The addition of only 200 g/t copper sulfate, which is ∼20% of that which is being used currently in the xanthate reagent scheme, improved the grade and the recovery. Seven different types of carboxymethylcellulose (CMC-1−CMC-7) were tested. CMC-1 was found to be the best as a depressant of gangue flotation. Copper sulfate appeared to differentiate the sphalerite surface well and facilitated chelation while the CMC changed the frothing characteristics of the slurry and prevented entrainment of gangue into float concentrate (froth). Studies on flotation kinetics also confirmed the improved selectivity attained by using copper sulfate and a CMC. The selectivity index (SI) for sphalerite, with respect to pyrite, improved from 0.88 to 2.35 when copper sulfate was added, and that for nonsulfidic gangue increased from 1.93 to 6.29 when CMC was added.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900305r

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5578–5583

Titre :	Ozonation combined with sonolysis for degradation and detoxification of m-nitrotoluene in aqueous solution
Type de document :	texte imprimé
Auteurs :	Zhiqiao He, Auteur ; Runye Zhu, Auteur ; Xing Xu, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5578–5583
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Sonolytic ozonation Nitroaromatic compound m-nitrotoluene Toxicity Aqueous solution
Résumé :	Sonolytic ozonation (US/O3 oxidation) is an advanced oxidation process that has become a focus of intense investigation. In this study, the nitroaromatic compound m-nitrotoluene (MNT) was chosen as a model substrate for degradation experiments in which pH, initial concentration of MNT, ozone dose, and US density were varied. At pH 10.0, initial concentration of MNT 400 mg/L, ozone dose 2.4 g/h, and US energy density 88 W/L, the efficiency of MNT removal reached 98% after 120 min. Of the initial degradation rate of MNT abatement, 9.8, 4.1, and 1.1 mg/(L min) were observed with US/O3, O3, and US, respectively. The variation of the concentrations of related anions (oxalate, acetate, formate, and nitrate ion) during the reaction process was ascertained by ion chromatography (IC). The major intermediates detected by gas chromatography/mass spectrometry (GC/MS) were 3-nitrobenzaldehyde, 3-nitrobenzoic acid, nitrobenzene, benzene, butene diacid, oxalic acid, and acetic acid. A degradation pathway is proposed on the basis of these findings. The acute toxicity of the reaction solution to zebra fish (Danio rerio) was estimated after US/O3 treatment. According to the decreasing lethal rate during the US/O3 process, it could be deduced that US/O3 is a powerful tool with which to achieve effective reduction of the toxicity of MNT.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801566z

[article]
in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5567–5577

Titre :	A review of eulerian simulation of geldart a particles in gas-fluidized beds
Type de document :	texte imprimé
Auteurs :	Junwu Wang, Auteur
Année de publication :	2009
Article en page(s) :	pp. 5567–5577
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Geldart particles Dilute gas-solid flow Eulerian simulation
Résumé :	Although great progress has been made in modeling the gas fluidization of Geldart B and D particles and dilute gas−solid flow by standard Eulerian approach, researchers have shown that, because of the limitation of computational resources and the formation of subgrid-scale (SGS) heterogeneous structures, Eulerian model with a suitable SGS model for constitutive law is necessary to simulate the hydrodynamics of large-scale gas-fluidized beds containing Geldart A particles. In this article, a state-of-the-art review of Eulerian modeling of Geldart A particles in gas-fluidized beds is presented. The available methods for establishing SGS models are classified into six categories, that is, empirical correlation method, scaling factor method, structure-based method, modified Syamlal and O’Brien drag correlation method, EMMS-model-based method, and correlative multiscale method. The basic ideas of those methods, as well as their advantages and disadvantages, are reviewed. Finally, directions for future research are indicated.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie900247t

Industrial & engineering chemistry research / Paul, Donald R. . Vol. 48 N° 12

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