Catalogue en ligne Bibliothèque Ecole Nationale Polytechnique d'Alger

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7501–7508

Titre :	Vapor-liquid equilibria predictions for alternative working fluids at low and moderate pressures
Type de document :	texte imprimé
Auteurs :	Shu-Xin Hou, Auteur ; Yuan-Yuan Duan, Auteur ; Xiao-Dong Wang, Auteur
Année de publication :	2008
Article en page(s) :	p. 7501–7508
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Working fluids Vapor-liquid equilibria Soave-Redlich-Kwong EoS
Résumé :	Alternative working fluid mixtures containing hydrofluoroethers, hydrofluorocarbons, alkanes, alcohols, ketones, and esters widely used as process fluids generally exhibit azeotropes, high nonideality, and association effects. In this work, the vapor−liquid equilibria for these mixtures are predicted using a combination of the Soave−Redlich−Kwong equation of state, zero reference pressure GE−EoS mixing rules, and the UNIFAC group contribution model. A new functional group assignment strategy was developed, and the model interaction parameters between groups were obtained from selected binary vapor−liquid equilibria data to give fairly good agreement between the calculated results and the experimental data. The method is also extended to ternary systems for VLE representations in a totally predictive manner with only the molecular structures, the critical parameters, and the acentric factors of the pure components needed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800133b

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7496–7500

Titre :	Dehydrogenation of alcohol mixtures to esters and ketones
Type de document :	texte imprimé
Auteurs :	F. H. A. Bolder, Auteur
Année de publication :	2008
Article en page(s) :	p. 7496–7500
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Fischer-Tropsch synthesis Alcohol fractions--dehydrogenation Oxygenated compounds
Résumé :	Fischer-Tropsch synthesis produces, among other things, complex mixtures of oxygenated compounds, such as primary and secondary alcohols, which are difficult to separate. The dehydrogenation of alcohol fractions in the C3 and C4 alcohol boiling ranges was investigated to determine whether the process would be suitable to produce different types of oxygenated compounds (esters and ketones), which could find application as solvents. The reaction was conducted in the presence of a Cu/Zn/Al2O3 catalyst in a pilot-plant-scale reactor in the temperature ranges of 219-278 °C with the propanol-rich feed and 219-300 °C with the butanol-rich feed (and at atmospheric pressure). The reaction products consisted of esters, ketones, and aldehydes (in decreasing order). The ester yield passed through a maximum with increasing temperature, as a result of secondary reactions, whereas the yield of ketones increased continually with temperature. The activity of the catalyst decreased by ∼15% over a period of 92 days. The selectivity of propyl propanoate, which is the main ester produced from the propanol feed mixture, decreased with time, while the yield of the ketones increased slightly.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800667p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7490–7495

Titre :	Effect of reactor length on the disinfection of fluids in Taylor-Couette photoreactor
Type de document :	texte imprimé
Auteurs :	Aklilu T. G. Giorges, Auteur ; John A. Pierson, Auteur
Année de publication :	2008
Article en page(s) :	p. 7490–7495
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Taylor-Couette flow UV disinfection system Reactor length Water-soluble caramel
Résumé :	When designing a Taylor−Couette flow ultraviolet (UV) disinfection system, the proper reactor size is obtained by balancing the diameter and height of the reactor. The disinfection level, which is based on reactor length (short and long reactors) and outside UV sources, is investigated to study the implications of reactor geometries. The experiment was performed by introducing three different sets of photon energy into the reactor from circumferential sources with different lengths. Three sets of equivalent photon energy are delivered to the system by limiting the photon exposed region and the number of sources. In addition, water-soluble caramel is used to establish the photon attenuation. The result indicated that there is no significant difference between long and short reactors with an equivalent UV-exposed region and similar flow rates. Indeed, the result shows that disinfection is strongly affected by the dosage delivered to the system. A short and wider photoreactor may yield similar disinfection levels as a tall and slender device, as long as the dosage delivered and the flow fields are similar. Thus, the reactor height and width can be sized depending on the application and other space limitations. A method is also presented to predict the mean intensity of the photoreactor with outside photon sources.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800250r

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7483–7489

Titre :	Use of the PPR78 model to predict new equilibrium data of binary systems involving hydrocarbons and nitrogen : comparison with other GCEOS
Type de document :	texte imprimé
Auteurs :	Romain Privat, Auteur ; Jaubert, Jean-Noël, Auteur ; Mutelet Fabrice, Auteur
Année de publication :	2008
Article en page(s) :	p. 7483–7489
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	PPR78 model Nitrogen Vapor-liquid equilibrium VTPR model PSRK model
Résumé :	Very recently, Privat et al. decided to add the nitrogen group to the PPR78 model. However, during the writing of their paper, new VLE data were published on three binary systems containing nitrogen: N2 + methane, N2 + ethane, N2 + and n-decane (new data on the ethane + methane system were also published). In this research note, the capability of the PPR78 model to predict these data along with two ternary systems involving nitrogen, methane, ethane, and n-decane is checked. Comparison with two other predictive models, VTPR and PSRK, is also performed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800636h

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7476–7482

Titre :	Study of the first isolated fungus capable of heavy crude oil biodesulfurization
Type de document :	texte imprimé
Auteurs :	Sarah Torkamani, Auteur ; Jalal Shayegan, Auteur ; Soheila Yaghmaei, Auteur
Année de publication :	2008
Article en page(s) :	p. 7476–7482
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Oil industry Desulfirization Fungus
Résumé :	To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to bring down the sulfur content in fuels. Oil supplies 38% of the worldwide energy, and as the light oil is limited and meanwhile the energy demand is increasing, it is a must to use heavy crude oil and therefore desulfurize it to meet environmental standards. As it is not feasible to desulfurize all the sulfur containing compounds of heavy crude oil by the existing methods (such as hydro-desulfurization) we have focused on biodesulfurization of heavy crude oil. We have isolated the first native fungus which has been identified as Stachybotrys sp. and is able to remove sulfur and nitrogen from heavy crude oil selectively at 30 °C. This fungus (labeled as WS4 with BBRC-9052 code) is able to desulfurize 76% and 64.8% of the sulfur content of heavy crude oil of Soroush oil field and Kuhemond oil field (with the initial sulfur contents of 5 wt % and 7.6 wt %, respecticely) in 72 and 144 h, respectively. We have studied the impacts of several parameters on heavy crude oil biodesulfurization efficiency of WS4 fungus strain such as initial pH of the medium, water−oil ratio, and number of spores in the suspension used for inoculation. A comparison between the heavy crude oil biodesulfurization capability of WS4 fungus and the thermophilic BBRC-9016 bacterium, which is active at 45 °C, has been conducted. The role of medium formulation on isolating a suitable desulfurizing microorganism has been presented. This fungus strain has been isolated as a part of the heavy crude oil biodesulfurization project initiated by Petroleum Engineering Development Company (PEDEC), a subsidiary of National Iranian Oil Company.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800494p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7465–7475

Titre :	Using computational fluid dynamics to study the dynamic behavior of the continuous mixing of Herschel-Bulkley fluids
Type de document :	texte imprimé
Auteurs :	Salwan Saeed, Auteur ; Farhad Ein-Mozaffari, Auteur ; Simant R. Upreti, Auteur
Année de publication :	2008
Article en page(s) :	p. 7465–7475
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Continuous-flow mixer Xanthan gum solution Dynamic model Computational fluid dynamics
Résumé :	A continuous-flow mixer was designed and built to study the mixing of xanthan gum solution, a pseudoplastic fluid possessing yield stress. The extent of flow nonideality was quantified using a dynamic model that incorporated two parameters: channeling and fully mixed volume in the vessel. Dynamic experiments were made using the frequency-modulated random binary input of a brine solution to determine the magnitude of nonideal flow parameters. The same experiments were simulated using a computational fluid dynamics (CFD) package (Fluent 6.2). CFD flow fields were used to obtain the system dynamic response to a tracer injection applied at conditions identical to the experimental ones. The extents of channeling and effective mixed volume were determined using the CFD model and then compared with the parameters obtained experimentally. Validated CFD flow fields enabled us to effectively monitor the effect of various operating conditions on flow nonideality, to relate flow pattern and cavern dimension to flow nonideality, to compare the efficiency of impellers, and to provide a pictorial synopsis of continuous-flow mixing operation.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800496x

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7456–7464

Titre :	The influence of biofilm on the effectiveness of ion exchange process
Type de document :	texte imprimé
Auteurs :	Anna Gorka, Auteur ; Dorota Papciak, Auteur ; Justyna Zamorska, Auteur
Année de publication :	2008
Article en page(s) :	p. 7456–7464
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Ammonia--ion exchange Zeolite Biofilm Fluidized bed reactor Plug flow reactor
Résumé :	The ion exchange of ammonia in a synthetic zeolite has been investigated in the presence of Biofilm of nitrifying bacteria. The Biofilm has been cultivated on the zeolite carrier under different hydrodynamic conditions in a plug flow reactor and in a fluidized bed reactor. Samples of the carrier covered by Biofilm have been withdrawn from the reactors and packed into a miniature ion exchange column that has been used to analyze the ion exchange characteristics, i.e., to determine ion exchange equilibria and the mass transport kinetics. For this purpose, the breakthrough curves have been registered at different ammonia loadings and different concentrations of sodium bicarbonate in the solution. To analyze the mass transport mechanism and quantify kinetic coefficients, we have exploited a linear driving force model (i.e., the LDF model) and the generalized model. The ion exchange and mass transfer characteristics of the Biofilm-covered carrier have been compared to those of the virgin zeolite. The effect of Biofilm on the mass transfer kinetics and ion exchange capacity was found to be induced by swelling properties of zeolite.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8002057

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7447–7455

Titre :	Laminar to turbulent transition and heat transfer in a microreactor : mathematical modeling and experiments
Type de document :	texte imprimé
Auteurs :	Andrej Pohar, Auteur ; Igor Plazl, Auteur
Année de publication :	2008
Article en page(s) :	p. 7447–7455
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Microreactor Heat transfer Flow rates Three-dimensional mathematical model
Résumé :	Heat transfer of aqueous flows was studied in a Y-shaped microreactor at different flow rates. In order to analyze the experimental data and to forecast the microreactor performance, a three-dimensional mathematical model with convection and conduction was developed, considering the velocity profile for laminar flow at steady state. The dependence of temperature on the thermophysical properties of water was implemented into the mathematical model. The microreactor investigated consists of a rectangular microchannel, which is divided into two inlet channels, a central channel, and two outlet channels. The average temperatures of water outflows were monitored. Very good agreement with the model calculations and the experimental data was achieved without any fitting procedure. In addition, the transition from laminar to turbulent flow was studied for different microchannel geometries, and the results showed that the channel aspect ratio and the angle of merging of two inlet channels substantially influence the critical Reynolds number.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8001765

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7441–7446

Titre :	Modeling systems containing alkanolamines with the CPA equation of state
Type de document :	texte imprimé
Auteurs :	Ane S. Avlund, Auteur ; Georgios M. Kontogeorgis, Auteur ; Michael L. Michelsen, Auteur
Année de publication :	2008
Article en page(s) :	p. 7441–7446
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Equation of state Alkanolamines Liquid-liquid equilibria Vapor-liquid equilibria
Résumé :	An association model, the cubic-plus-association (CPA) equation of state (EoS), is applied for the first time to a class of multifunctional compounds (alkanolamines). Three alkanolamines of practical and scientific significance are considered; monoethanolamine (MEA), diethanolamine (DEA), and methyl diethanolamine (MDEA). Vapor pressures and liquid densities, as well as solvatochromic parameters and mixture liquid−liquid equilibria (LLE) data with alkanes are used to estimate the five pure-compound parameters. Vapor−liquid equilibria (VLE) calculations for cross-associating mixtures, especially those with water, are used in the validation of the parameters. The influence on the results of the association scheme, cross-association combining rules, interaction parameters, and the data available is discussed also, in connection with other aqueous cross-associating mixtures previously studied using the CPA equation of state (alcohols, amines, and glycols).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800040g

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7433–7440

Titre :	Impact of kraft process modifications on eucalyptus globulus pulping performance and polysaccharide retention
Type de document :	texte imprimé
Auteurs :	Ana Sofia Santiago, Auteur ; Carlos Pascoal Neto, Auteur
Année de publication :	2008
Article en page(s) :	p. 7433–7440
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Alkali Anthraquinone Eucalyptus globulus kraft
Résumé :	The impact of effective alkali (EA) splitting and anthraquinone (AQ) addition on Eucalyptus globulus kraft pulping yield and pulp quality was investigated. AQ addition to kraft pulping enhances the rate of delignification, leading to alkali saving and reducing time at maximum temperature. A 1.9% total yield increase was observed, assigned to the enhancement of both cellulose and xylan retention but also due an increase of rejects content. Contrary to results described in the literature for other woods, the use of an even effective alkali concentration profile throughout the cook of E. globulus did not affect pulp yield or carbohydrate composition of screened pulp. However, EA profiling resulted in a higher pulp viscosity, indicating a lower degradation of cellulose chains along the pulping. Such results were interpreted taking into account the peculiar chemical structure of E. globulus wood components.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071488g

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7424–7432

Titre :	Analysis of the conditions for the inception of natural pulsing flow in cocurrent packed columns
Type de document :	texte imprimé
Auteurs :	Talgat A. Akramov, Auteur ; Petr Stavarek, Auteur ; Vladimir Jiricny, Auteur
Année de publication :	2008
Article en page(s) :	p. 7424–7432
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Packed-bed column--mass balance Holdup formation Hydrodynamic regime
Résumé :	Functional analysis of mass balances in a cocurrent packed-bed column has been carried in conjunction with analysis of the locally linear relationship between liquid holdup and phase velocities and first-order kinetics of the rate of holdup formation. The analysis indicates that the stability of the hydrodynamic regime in the bed is limited by the condition k(λ − γ)L < 2. Furthermore, for k(λ − γ)L > 0.5, the amplitude of the pulsations appearing in the bed in response to small flow perturbations was found to amplify. For k(λ − γ)L approaching 2, the flow disturbances are amplified very strongly. Experimental measurement of the liquid holdup, analysis of the kinetics of liquid holdup formation, and determination of the limits of the appearance of natural pulsations from pressure drop fluctuations show that the limit of inception of natural pulsations closely adheres to the line k(λ − γ)L = 2 where our analysis predicts very strong amplification of flow disturbances.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800501q

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7419–7423

Titre :	Screening test of solid amine sorbents for CO2 capture
Type de document :	texte imprimé
Auteurs :	Seungmoon Lee, Auteur ; Thomas P. Filburn, Auteur ; Mac Gray, Auteur
Année de publication :	2008
Article en page(s) :	p. 7419–7423
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	CO2--absorption Absorption/desorption rate Cyclic capacity Cycle decay effect
Résumé :	In this study, the absorption properties of CO2 in seven different solid amine absorbents were measured. The specific characteristics, such as absorption capacity, absorption/desorption rate, cyclic capacity, cycle decay effect, temperature of reaction in the absorber, and optimal conditions for the CO2 absorption process were measured. This absorption process occurred at two temperatures—either 296.15 or 313.15 K—while the desorption process temperature was raised to 348.15 K. The solid amines (TEPAN and E-100AN) demonstrated higher cyclic capacity than others under these conditions. Our testing showed high reproducibility for the CO2 capture of TEPAN and E-100AN in measuring their cyclic capacity. Diminished cyclic capacities were noted for the MEA and 194B materials, with measured drops at the third cycle of about 16.17% and 15.79% lower than those in the first cycle, respectively.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8006984

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7414–7418

Titre :	Gas-liquid-liquid three-phase reactive extraction for the hydrogen peroxide preparation by anthraquinone process
Type de document :	texte imprimé
Auteurs :	Yongxi Cheng, Auteur ; Wang, Li, Auteur ; Shuxiang Lü, Auteur
Année de publication :	2008
Article en page(s) :	p. 7414–7418
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gas-liquid-liquid three-phase reactive extraction Hydrogen peroxide Anthrahydroquinone--oxidation
Résumé :	The gas−liquid−liquid three-phase reactive extraction at elevated pressures for the preparation of hydrogen peroxide by anthraquinone route was investigated experimentally. The integrated process of the oxidation reaction of anthrahydroquinone in the working solution by oxygen from the oxygen-containing gas and the extraction of hydrogen peroxide from the working solution with deionized water were carried out in a sieve plate column of 50 mm in diameter at 0.1−0.6 MPa and 323 K. All operating conditions focused in this work such as operating pressure, superficial gaseous velocity, and oxygen concentration in the initial gas were the advantageous parameters for enhancing the conversion of anthrahydroquinone in the integrated process, because the rate-controlling step of the oxidation reaction of anthrahydroquinone is the mass transfer of oxygen at the interface between the gaseous phase and the organic phase. The agitating effect caused by the gaseous phase made the droplets of the organic phase become smaller and, thus, increased the liquid−liquid interfacial contact areas, resulting in the improvement of the mass transfer of hydrogen peroxide at the water−working solution interface. However, a large excess of the gas superficial velocity caused the decrease in the extraction efficiency of hydrogen peroxide. The real gas superficial velocity on the upper section of the extraction column at the high initial concentration of oxygen was lower than that at the low oxygen concentration, resulting in the decrease of the extraction efficiency of hydrogen peroxide. There was no change in the extraction efficiency of hydrogen peroxide with increasing operating pressure, although the mass transfer rate of hydrogen peroxide at the water−working solution interface increased slightly.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800500y

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7405–7413

Titre :	Comparative study on adsorptive removal of thiophenic sulfurs over Y and USY zeolites
Type de document :	texte imprimé
Auteurs :	Sakdinun Nuntang, Auteur ; Pattarapan Prasassarakich, Auteur ; Chawalit Ngamcharussrivichai, Auteur
Année de publication :	2008
Article en page(s) :	p. 7405–7413
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Organic sulfur Adsorption FAU zeolites NaY HUSY cation-exchanged
Résumé :	Removal of organic sulfur compounds by using an adsorption process was carried out at ambient temperature and pressure. FAU zeolites, including NaY, HUSY cation-exchanged with metal ions such as Cu, Ni, Zn, and La, have been applied as adsorbents in the desulfurization of model and real transportation fuels. The results showed that the type of metal ion-exchanged, amount of metal ion-exchanged, and structure of zeolite have important roles in the removal of each organic sulfur. LaNaY, LaHUSY, and CuNaY possessed highest adsorption capacity toward thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT), respectively. Among the tested adsorbents, LaHUSY exhibited highest adsorption selectivity to BT and DBT in the presence of naphthalene. The comparative study indicated that La3+ is capable of strongly adsorbing the aromatic sulfur compounds via both direct interaction at sulfur atom and via π-electronic interaction. Adsorptive desulfurization of real diesel over LaHUSY reduced the sulfur level from 229 to less than 50 ppm, and the adsorption selectivity to 4-methyldibenzothiophene (4-MDBT) was highest.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie701785s

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7397–7404

Titre :	Influences for the addition of ethanol to the absorption system on the interfacial disturbances and mass transfer performance
Type de document :	texte imprimé
Auteurs :	Honda Wu, Auteur ; Tsair-Wang Chung, Auteur
Année de publication :	2008
Article en page(s) :	p. 7397–7404
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Triethylene glycol Diethylene glycol Interfacial mass transfer phenomena Absorption system
Résumé :	To study the interfacial mass transfer phenomena of water vapor absorbed by TEG (triethylene glycol) and DEG (diethylene glycol) solutions, an absorption system was designed and tested in this study. The surface tensions of TEG and DEG solutions were varied by adding a liquid with lower surface tension to observe the interfacial disturbances and the mass transfer performance of the absorption system. In this study, ethanol was added to the absorbent solution. The traditional variable of driving force was replaced by the variable of surface tension times driving force to compare the variation of mass transfer coefficients of systems with and without ethanol added to the absorbent solution. The results showed that surface tension significantly affected the mass transfer performance in the gas−liquid interface. Both mass transfer coefficient and enhancement factors were calculated to analyze the effects of interfacial disturbance on mass transfer performance. The photographs showed that when ethanol was added to the surface of the TEG solution, the interfacial disturbance on the surface of the TEG solution was significant. The experimental results also demonstrated that the mass transfer coefficients were increased due to the addition of ethanol to the absorbent solution. The values of the defined enhancement factor were from 1.047 to 1.143 for the system with DEG solution and from 1.064 to 1.161 for the system with TEG solution. Both driving force and surface tension were important physical properties that affected the mass transfer phenomena of the absorption system. The interfacial disturbance resulting from the addition of ethanol to the absorbent solution can be used to enhance the mass transfer performance for absorption heat pump and absorption air-conditioning systems.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071534c

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7390–7396

Titre :	Dual nature of polyethylene glycol-based aqueous biphasic extraction chromatographic (ABEC) resins : uptakes of perchlorate versus mercury(II)
Type de document :	texte imprimé
Auteurs :	Meghna Dilip, Auteur ; Scott T. Griffin, Auteur ; Scott K. Spear, Auteur
Année de publication :	2008
Article en page(s) :	p. 7390–7396
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Polyethylene glycol ABEC resins Mercury(II) cations Perchlorate anions
Résumé :	Polyethylene glycol (PEG)-grafted aqueous biphasic extraction chromatographic (ABEC) resins have been shown to remove both mercury(II) cations (Hg2+) or perchlorate anions (ClO4−) from aqueous media under different conditions. Water destructuring (chaotropic) anions such as perchlorate (ΔGhyd = −214 kJ/mol) partitioned to ABEC resin in the presence of water structuring (kosmotropic) anions, with increased affinity for the resin as the kosmotropic nature of the anion increased (Cl− < SO42− < PO43−), and could be easily stripped using water. However, while the partitioning of ClO4− to the resin was possible only in the presence of a kosmotropic salt; Hg2+ was retained from the resin only in the absence of such salts (i.e., from pure water) and stripped from the resin when eluted with kosmotropic salt solutions. Here, the different mechanisms for uptake of these ions by an ABEC resin are explored.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800841j

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7381–7389

Titre :	Conceptual design and simulation tools applied to the evolutionary optimization of a bioethanol purification plant
Type de document :	texte imprimé
Auteurs :	Patricia M. Hoch, Auteur ; Jose Espinosa, Auteur
Année de publication :	2008
Article en page(s) :	p. 7381–7389
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Bioethanol purification plant Conceptual model Rigorous models
Résumé :	We present an evolutionary optimization procedure applied to the design and simulation of the unit operations in a bioethanol purification plant. Conceptual and rigorous models are used; the first are utilized to determine initial values for design and operating variables, and then rigorous simulation is used to refine the results. The use of rigorous models allows for the elimination of simplifying assumptions, the interconnection of equipment, and the calculation of the operating and investment costs. Once an initial design of the purification plant is obtained, opportunities of improvement are easily recognized and then tested by performing the design and simulation steps until a cost-effective bioethanol purification plant is achieved. The methodology is applied to the purification process for a feed leaving the fermentation step of a conventional corn dry-grind processing facility producing 24 million L/year of ethanol and 19 million kg/year of distiller’s dry grains with solubles (DDGS). The feed to the purification plant (22 170 kg/h) is mainly composed by ethanol (10.80% w/w) and water (88.98% w/w) with traces of methanol (0.0226% w/w) and fusel (0.2009% w/w). Following the proposed approach, two initial designs of the whole purification plant using different technologies to break the azeotrope between ethanol and water are compared in terms of operating and investment costs. Savings in overall costs of about 32% are achieved by the alternative distillation/pervaporation in comparison with the option distillation/extractive distillation. Then, the membrane-based technology is adopted as the core of the purification process and a search for further improvements is performed. Four alternative designs were evaluated. In each case, the steam consumption of the evaporation sector is reduced by 1 300 kg/h by condensing the ethanol-rich side stream from the main rectification column in the first effect of the train. Finally, the option characterized by an ethanol composition in the ethanol-rich side stream of 91.24% w/w is selected as the quasi-optimal design because overall costs are reduced by 6.67% with respect to the base case and by 11.48% with respect to the worst case analyzed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800450a

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7375–7380

Titre :	Reaction kinetics of carbonyl sulfide (COS) with diethanolamine in methanolic solutions
Type de document :	texte imprimé
Auteurs :	Rodrigo Rivera-Tinoco, Auteur ; Chakib Bouallou, Auteur
Année de publication :	2008
Article en page(s) :	p. 7375–7380
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Carbonyl sulfide Diethanolamine Methanolic solutions
Résumé :	In this work, the kinetics of carbonyl sulfide (COS) absorption in a hybrid solvent containing diethanolamine (DEA) dissolved in methanol was studied. The amine concentrations and temperatures ranged from 380 to 2030 mol m−3 and from 298 to 323 K, respectively. With the purpose of estimating reaction rate constants for the COS−DEA system, the rigorous modeling of COS absorption was carried out based on the two-step zwitterion mechanism, used until now in the modeling of the absorption of carbon dioxide and sulfur compounds by alkanolamine aqueous solutions. A downhill simplex optimization method was developed to determine the reaction rate constants, and simultaneously an iterative procedure was followed to estimate the enhancement factor of the COS absorption. As the results show, these optimization procedures led successfully to the appropriate fitting between the experimental and modeled data and also confirm the two-step zwitterion mechanism for this absorption system.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8002649

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7368–7374

Titre :	Film-penetration model for nonisothermal physical gas absorption
Type de document :	texte imprimé
Auteurs :	Siddharth G. Chatterjee, Auteur ; Elmar R. Altwicker, Auteur
Année de publication :	2008
Article en page(s) :	p. 7368–7374
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Film-penetration model Physical gas absorption
Résumé :	A two-parameter model, which utilizes the hybrid film−penetration concept, is developed for describing exothermic physical absorption of a gas into a liquid. The model is applied to the absorption of dry saturated water vapor into aqueous lithium bromide solution, which system is used in absorption cooling. The conventional film and penetration models predict constant values of 0.55 and 6.59 K for the interfacial temperature rise, respectively, and also suggest that the rate of absorption at the gas−liquid interface will be depressed by 3 (film model) and 40% (penetration model) compared to assumed isothermal absorption at the bulk liquid temperature. The holistic film−penetration model resolves this large discrepancy between the film and penetration models, which are fragmentary perspectives of the absorption process.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800154w

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7361–7367

Titre :	Acid gas permeation behavior through poly(ester urethane urea) membrane
Type de document :	texte imprimé
Auteurs :	T. Mohammadi, Auteur ; M. Tavakol Moghadam, Auteur ; M. Saeidi, Auteur
Année de publication :	2008
Article en page(s) :	p. 7361–7367
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Pure gases Poly(ester urethane urea) membrane
Résumé :	Permeation behavior of pure gases (CO2, N2, CH4) and ternary gas mixtures of CO2, CH4, and H2S through a poly(ester urethane urea) membrane was investigated at different pressures, temperatures, and feed compositions. Permeances of CO2, CH4, and H2S through the membrane were determined at temperatures of 35, 45, and 55 °C, and pressures of 10, 20, and 30 bar. Effects of temperature, pressure, and stage cut on the permeability of gases through the membrane were experimentally studied. Since the main objective of this study was to evaluate the aforesaid membrane for its ability to remove acid gas application, the measured selectivity of poly(ester urethane urea) in this study was compared with that of some other polymeric membranes at nearly the same operating conditions. Maximum selectivities of 43 and 16 were measured for H2S/CH4 and CO2/CH4, respectively. Average permeances of 95 and 45 GPU for H2S and CO2 were achieved, respectively.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071493k

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7357–7360

Titre :	Effect of SOx adsorption on layered double hydroxides for CO2 capture
Type de document :	texte imprimé
Auteurs :	M. K. Ram Reddy, Auteur ; Z. P. Xu, Auteur ; G. Q. (Max) Lu, Auteur
Année de publication :	2008
Article en page(s) :	p. 7357–7360
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	SOx Layered double hydroxide Sorption
Résumé :	In this work, we investigate the effect of SOx on the performance of layered double hydroxide (LDH) derivatives used as adsorbent for CO2 capture. LDH derivatives such as layer double oxide (LDO) have shown great potential for high-temperature CO2 separation from flue gases. We found that even at low flue gas feed concentrations of SOx (0.1%), the sorption values were very high, reaching a maximum sorption capacity equivalent to 11.04% of the sorbent weight. Regeneration of LDO in pure helium resulted in regaining up to 58% of its original sorption capacity. Temperature cycling also revealed the irreversible nature of SOx sorption. In addition, regeneration after CO2/SOx and SOx/CO2 sorption experiments showed that SOx replaces CO2. SOx sorption over CO2 was favored due to the strong acid−base interactions between SOx and LDO, thus forming sulfites and sulfates. Hence, LDH derivatives for CO2 capture require a de-SOx unit operation upstream.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8004226

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7347–7356

Titre :	Normalized decoupling : a new approach for MIMO process control system design
Type de document :	texte imprimé
Auteurs :	Wen-Jian Cai, Auteur ; Wei Ni, Auteur ; Mao-Jun He, Auteur
Année de publication :	2008
Article en page(s) :	p. 7347–7356
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Decoupling control system Two-input process Two-output process
Résumé :	In this paper, a novel engineering oriented decoupling control system design method for two-input, two-output processes is presented. By employing the concept of integrated error, gain and phase changes of a transfer function when other loops are closed can be uniquely determined. Consequently, an equivalent transfer function matrix for a closed-loop control system can be obtained and its relations with the original process transfer function matrix are derived. On the basis of the equivalent transfer function matrix, parameters of a stable, proper, and causal ideal diagonal decoupler can then be easily determined by proper parameter assignments of the decoupled transfer function matrix elements. The method avoids the drawbacks of existing decoupling schemes, is very simple and can be easily understood, and can be implemented by field control engineers. An industrial process is employed to demonstrate its simplicity in design and effectiveness in control system performance.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8006165

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7335–7346

Titre :	Development of an optimal sensor placement procedure based on fault evolution sequences
Type de document :	texte imprimé
Auteurs :	Jung Yang Chen, Auteur ; Chuei-Tin Chang, Auteur
Année de publication :	2008
Article en page(s) :	p. 7335–7346
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Sensor placement procedures SDG-based strategy
Résumé :	The diagnostic resolution issues are usually addressed with a quantitative or semiquantitative approach in the reported studies concerning sensor placement procedures. Since the required information for implementing the traditional methods may not be always available, a SDG-based strategy is proposed in this paper to design the sensor networks on the basis of qualitatively predicted fault evolution sequences. To achieve a maximum level of resolution and, at the same time, to ensure observability, the corresponding design problems are formulated as integer programs in this work. Two alternative strategies are also developed for producing the optimal solutions. The feasibility of the proposed method is demonstrated with three examples.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie701767v

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7323–7334

Titre :	Bottom-up modeling of the steam consumption in multipurpose chemical batch plants focusing on identification of the optimization potential
Type de document :	texte imprimé
Auteurs :	Andrej Szijjarto, Auteur ; Stavros Papadokonstantakis, Auteur ; Ulrich Fischer, Auteur
Année de publication :	2008
Article en page(s) :	p. 7323–7334
Note générale :	Chemical engneering
Langues :	Anglais (eng)
Mots-clés :	Steam consumption Multipurpose chemical batch plant
Résumé :	A detailed approach for modeling the steam consumption in a multipurpose chemical batch plant was developed, tested, and used for analysis of the energy-efficiency. The main advantage of the approach presented in this paper compared to available modeling approaches is the ability to describe the transient steam consumption. Thus, the new approach can be used for the dynamic optimization of batch operations with respect to the energy efficiency. The bottom-up method was implemented by modeling particular unit operations (UOs) in a case study plant, and validation was accomplished with direct measurements on both UO and building level. The principle of the bottom-up model is a detailed energy balance of each particular UO for which process parameter measurements are necessary as input data. These were extracted from the measurements archive of the case study plant for a period of two months. Process data from almost 1000 sensors installed in ca. 100 UOs were acquired, transformed into a time-series with common time basis, and used as an input data for the model. Special attention was paid to model the losses of the UOs because in earlier studies it was found that these are significant. Loss models were developed in the form of empirical parametric equations considering the losses due to radiation and the internal losses in the heating/cooling system due to inefficient operation. The parameters of the loss models were fitted, based on the developed methodology, to steam measurements of 4 UOs and consequently integrated into the overall bottom-up model for modeling other UOs as well. The energy usage efficiency of the UOs was inferred and the optimization spots were identified. The results in the case study plant have indicated that the energy savings potential for particular UOs with low steam-usage efficiency can be easily identified and serve as a good hint for the overall plant energy auditing and steam consumption optimization.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071291o

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7312–7322

Titre :	Constrained Bayesian state estimation using a cell filter
Type de document :	texte imprimé
Auteurs :	Sridhar Ungarala, Auteur ; Keyu Li, Auteur ; Zhongzhou Chen, Auteur
Année de publication :	2008
Article en page(s) :	p. 7312–7322
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Nonlinear/non-Gaussian processes Constrained cell filter
Résumé :	Constrained state estimation in nonlinear/non-Gaussian processes has been the domain of optimization based methods such as moving horizon estimation (MHE). MHE has a Bayesian interpretation, but it is not practical to implement a recursive MHE without assumptions of Gaussianity and linearized dynamics at various stages. This paper presents the constrained cell filter (CCF) as an alternative to MHE, requiring no linearization, jacobians, or nonlinear program. The CCF computes a piecewise constant approximation of the state probability density function with support defined by constraints; thus, all point estimates are constrained. The CCF can be more accurate and orders of magnitude faster than MHE for problems of a size as investigated in this work.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070249q

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7304–7311

Titre :	Internal heat integration and controllability of double feed reactive distillation columns, 2. effect of catalyst redistribution
Type de document :	texte imprimé
Auteurs :	M. V. Pavan Kumar, Auteur ; Nitin Kaistha, Auteur
Année de publication :	2008
Article en page(s) :	p. 7304–7311
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Catalyst redistribution Reactive distillation column
Résumé :	The effect of internal heat integration by catalyst redistribution on the controllability of an ideal and a methyl acetate reactive distillation (RD) column is studied. Conventional designs with feeds immediately above and below the reactive section are internally heat integrated by (a) extending the reactive section into the stripping section with catalyst redistribution, followed by (b) altering the feed tray locations. For the ideal RD system, only reactive section extension results in a design with a reboiler energy savings of 7.7%. The design obtained by reactive section extension followed by altered feed tray locations gives greater energy savings of 18.2%. For the methyl acetate system, simple reactive section extension with no change in the feed tray locations gives the most energy-efficient design with an energy savings of 39.7%. A comparison of the closed-loop performance of the two-point temperature control structures for the different designs demonstrates that temperature inferential control can be used to regulate the internally heat-integrated designs of both the ideal and methyl acetate systems. The controllability of the ideal RD column with full internal heat integration (both items (a) and (b) above) is found to be inferior to the conventional design. For the methyl acetate system, the controllability of the internally heat-integrated design is improved, relative to the conventional design.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071639f

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7294–7303

Titre :	Internal heat integration and controllability of double feed reactive distillation columns, 1. effect of feed tray location
Type de document :	texte imprimé
Auteurs :	M. V. Pavan Kumar, Auteur ; N. Kaistha, Auteur
Année de publication :	2008
Article en page(s) :	p. 7294–7303
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Feed tray locations Reactive distillation columns Steady-state bifurcation analysis
Résumé :	The impact of altering feed tray locations (for the purpose of saving energy) on the controllability of double feed reactive distillation (RD) columns is evaluated for two case studies: a hypothetical ideal RD column and a methyl acetate RD column. Energy savings of 18.3% and 36.4% over the conventional design (feed immediately above and below the reactive zone) is achieved for the ideal and methyl acetate systems, respectively. A steady-state bifurcation analysis shows that, for both systems, output multiplicity, with respect to reboiler duty, occurs at a fixed reflux rate for the different designs (conventional/altered feed tray location). The output multiplicity is eliminated at a fixed reflux ratio. Closed-loop dynamic simulation results show that the controllability of the internally heat integrated ideal RD column deteriorates, compared to the conventional design. Unlike the conventional design, temperature-based inferential control is infeasible and composition-based control structures must be used. For the methyl acetate column, on the other hand, heat integration by altering the feed locations entails no loss in controllability using two-point temperature inferential control.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071638n

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7284–7293

Titre :	Multiobjective design of reactive distillation with feasible regions
Type de document :	texte imprimé
Auteurs :	Rui M. Filipe, Auteur ; Scott Turnberg, Auteur ; Steinar Hauan, Auteur
Année de publication :	2008
Article en page(s) :	p. 7284–7293
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Complex reactive distillation columns Subcooled feed streams Superheated feed streams
Résumé :	This work addresses the multiobjective design of complex reactive distillation columns through the use of feasible regions. A cost indicator reflecting energy usage and column size is introduced and used to build the Pareto surface describing the optimal combinations of cost and performance. The study includes the use of superheated and subcooled feed streams and searches for the optimal distribution of feeds and catalyst inside the column. The technique is first illustrated for a base case system with ideal vapor−liquid equilibrium and then for two variants with different volatilities for reactants and products. The best trade-off solutions for each system are identified, the operating conditions analyzed, and a selected number of cases investigated further using rigorous simulation in Aspen Plus. Important insights gained and a few heuristic rules about the distribution of the reaction and feed in the column are presented. Furthermore, a methodology that may potentially contribute to overcome limitations on catalyst volume by increasing the specific reaction turnover is presented.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800306b

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7274–7283

Titre :	Approximate maximum likelihood parameter estimation for nonlinear dynamic models : application to a laboratory-scale nylon reactor model
Type de document :	texte imprimé
Auteurs :	M. Saeed Varziri, Auteur ; Kim B. McAuley, Auteur ; P. James McLellan, Auteur
Année de publication :	2008
Article en page(s) :	p. 7274–7283
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Nylon reactor model Approximate maximum likelihood estimation
Résumé :	In this article, parameters and states of a laboratory-scale nylon 612 reactor model (Schaffer et al. Ind. Eng. Chem. Res. 2003, 42, 2946−2959; Zheng et al. Ind. Eng. Chem. Res. 2005, 44, 2675−2686; and Campbell, D. A. Ph.D. Thesis, Department of Mathematics and Statistics, McGill University, Montreal, Quebec, Canada, 2007) are estimated using a novel approximate maximum likelihood estimation (AMLE) algorithm (Poyton et al. Comput. Chem. Eng. 2006, 30, 698−708; Varziri et al. Comput. Chem. Eng., published online, http://dx.doi.org/10.1016/j.compchemeng.2008.04.005; Varziri et al. Ind. Eng. Chem. Res. 2008, 47, 380−393; and Varziri et al. Can. J. Chem. Eng., accepted for publication). AMLE is a method for estimating the states and parameters in differential equation models with possible modeling imperfections. The nylon reactor model equations are represented by stochastic differential equations (SDEs) to account for any modeling errors or unknown process disturbances that enter the reactor system during experimental runs. In this article, we demonstrate that AMLE can address difficulties that frequently arise when estimating parameters in nonlinear continuous-time dynamic models of industrial processes. Among these difficulties are different types of measured responses with different levels of measurement noise, measurements taken at irregularly spaced sampling times, unknown initial conditions for some state variables, unmeasured state variables, and unknown disturbances that enter the process and influence its future behavior.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800503v

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7264–7273

Titre :	Model predictive control of nonlinear distributed parameter systems using spatial neural-network architectures
Type de document :	texte imprimé
Auteurs :	Wei, Wu, Auteur ; San-Yin Ding, Auteur
Année de publication :	2008
Article en page(s) :	p. 7264–7273
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Partial differential equations Neural-network architecture Closed-loop control system
Note de contenu :	In this paper the distributed parameter systems comprise first-order partial differential equations coupled with ordinary differential equations. Through time and space discretization the explicit formulation of finite-difference model is constructed. Under effects of unknown disturbances and parameter uncertainties, an online learning algorithm, by virtue of the minimal output error between the system and neuro model, is developed. If only a few output measurements are available, the spatial feedforward neural-network architecture is integrated into the nondistributed predictive control framework. The stability analysis of the closed-loop control system is addressed through the discrete-time Lyapunov function approach. Two examples including a bioreactor system governed by the population balance equation and the nonisothermal tubular reactor system are used to verify the effectiveness of the proposed method.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800474m

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7257–7263

Titre :	Case study on tubular reactor hot-spot temperature control for throughput maximization
Type de document :	texte imprimé
Auteurs :	Sadanand Singh, Auteur ; Shivangi Lal, Auteur ; Nitin Kaistha, Auteur
Année de publication :	2008
Article en page(s) :	p. 7257–7263
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Tubular reactor Hot-spot temperature control Gas-phase alkylation
Résumé :	Auctioneering hot-spot temperature control of a highly exothermic cooled tubular reactor (constant coolant temperature) for cumene production via the irreversible gas-phase alkylation of benzene with propylene (A + B → C) is studied. Specifically, three control configurations are quantitatively evaluated for tightness of hot-spot temperature control and maximum achievable process throughput with reactor cooling duty as the bottleneck constraint. The configurations manipulate respectively the reactor cooling duty (CS1), the reactor inlet temperature (CS2), and the fresh propylene feed (CS3) for regulating the hot-spot temperature. Plantwide dynamic simulation results show that tightest hot-spot temperature control is achieved by the direct manipulation of the reactor cooling duty (CS1). Use of reactor inlet temperature as the manipulation handle (CS2) is not recommended due to large deviations in the reactor temperature profile for a throughput increase. Manipulating the fresh propylene feed rate (limiting reactant) as in CS3 provides loose but acceptable hot-spot temperature control. CS3 is most preferred for throughput maximization as the reactor is operated at the bottleneck constraint of maximum heat removal capacity. For the sample case study, the maximum achievable throughput increases by more than 7% by use of CS3 (over CS1).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071287c

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7250–7256

Titre :	Capillary forces in wet paper
Type de document :	texte imprimé
Auteurs :	Theo G.M. Van de Ven, Auteur
Année de publication :	2008
Article en page(s) :	p. 7250–7256
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Wet paper Capillary forces Static friction
Résumé :	An analysis of capillary forces in wet paper and between two wet sheets leads to a number of interesting conclusions. Experimentally, it is found that the (static) friction force between two rewetted sheets is a maximum (4.8 kN/m2) at a solids content of 38%, at which the air−water surface area is estimated to be a maximum. Assuming that, at this concentration, all of the water between fibers is in liquid bridges between fiber crossings, theory predicts a friction force of similar magnitude. Making the same assumptions in predicting the strength of wet sheets leads to a theoretical prediction that is an order of magnitude smaller than the observed tensile strength. Contrary to theoretical predictions for smooth spheres or cylinders, the Laplace forces decrease to zero when the water content between the fibers goes to zero, at the fiber saturation point. This is likely caused by the surface roughness of the fibers. It can be concluded that the Laplace pressure is unimportant in determining the strength of wet paper, contrary to the assumptions of previous studies. The observations that the wet web strength increases with decreasing capillary forces and that the wet strength is smaller than predicted by capillary theory confirm that the wet web strength is not determined by capillary forces alone, but must involve an additional mechanism, likely to be an entanglement friction.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800423r

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7242–7249

Titre :	Development of an empirical model to predict the effect of contaminants in liquid-liquid extraction
Type de document :	texte imprimé
Auteurs :	S. N. Ashrafizadeh, Auteur ; J. Saien, Auteur ; B. Reza, Auteur
Année de publication :	2008
Article en page(s) :	p. 7242–7249
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Slater Liquid-liquid extraction unitsWater-acetone-toluene system
Résumé :	In the presence of surface-active reagents, the flux of mass transfer into/from the droplets drastically decreases within the liquid−liquid extraction units. Therefore, particular design equations are required to incorporate the presence of contaminants in the design of industrial-scale extraction columns. In the combinatorial model of Slater, the mass-transfer coefficients for the continuous and dispersed phases are corrected with the aid of a contamination factor. However, since the latter factor in the Slater model is originally obtained from the experimental data, the Slater model is unable to predict the behavior of an extraction system where the experimental data are not available. In this research, the model of Slater, i.e., single-drop single-solvent model, was employed to simulate the experimental data of a water−acetone−toluene system in the presence of three surface-active reagents, i.e., SDS, Triton X-100, and DTMAC. These components exhibit anionic, cationic, and nonionic surfactants, respectively. The experimental data provided by Saien et al. for both directions of the mass transfer, i.e., continuous to dispersed phases and vice versa, were employed. Based on the experimental data along with the theoretical principles, an empirical model for the contamination factor was developed. The provided model predicts the mass-transfer coefficients within ±4% of certainty only through the physical properties data of the phases, independent of the surfactant type. Two different mechanisms for the mass transfer within the liquid droplets, depending on the size of the droplets, have been recognized. Simulation of the extraction system by the aid of the present model, along with the combinatorial model of Slater and the terminal velocity model of Grace, predicts the experimental results satisfactorily.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0715557

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7236–7241

Titre :	Fabrication of mesoporous silica coating by electrophoretic deposimtion
Type de document :	texte imprimé
Auteurs :	Hideyuki Negishi, Auteur ; Akira Endo, Auteur ; Takao Ohmori, Auteur
Année de publication :	2008
Article en page(s) :	p. 7236–7241
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Applying electrophoretic deposition Mesoporous silicate Spray-drying method
Résumé :	The technological feasibility of applying electrophoretic deposition (EPD) to ordered mesoporous silicate (MPS) powder has been studied. The EPD technique was investigated for the fabrication of an MPS thick film using MPS synthesized by the spray-drying method. It was found that the MPS powder deposition rate was low with an alcohol EPD bath and very high with an acetone EPD bath. The deposition amount could be easily controlled by changing the MPS powder concentration, the applied dc voltage, and the deposition time. An MPS particle/acetone suspension in which the particles were negatively charged showed the highest deposition rate among the tested organic solvents. MPS powder was deposited by EPD at 50 V for 10 min onto a tubular stainless steel substrate, and a uniform coating approximately 250 μm in thickness was obtained. After heat treatment at 573 K, the MPS powder could be fixed on the substrate without the addition of binders. The obtained MPS thick film had the same porous structure and nitrogen and water vapor adsorption properties as the parent MPS powder.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071473i

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7226–7235

Titre :	Structure evolution of Co/alumina-pillared clay catalysts under thermal treatment at increasing temperatures
Type de document :	texte imprimé
Auteurs :	A. Gil, Auteur ; R. Trujillano, Auteur ; M. A. Vicente, Auteur
Année de publication :	2008
Article en page(s) :	p. 7226–7235
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Thermal treatment Co/alumina-pillared montmorillonite catalyst X-ray diffraction
Résumé :	The aim of this work is to study the effect of the thermal treatment at 350 and 500 °C on the structure of a Co/alumina-pillared montmorillonite catalyst. For this purpose, the X-ray powder diffraction patterns of the solids, the nitrogen physisorption data at −196 °C, the micropore-size distributions, the UV−vis and NIR spectroscopies of the dried materials, the gravimetric and differential thermal analyses, and the temperature-programmed reduction analyses of the supported cobalt catalysts have been analyzed and compared. The impregnation with cobalt and the temperature has modified the textural properties of the alumina-pillared clay supports, giving rise to a loss of surface area and micropore volume in the final catalysts. Co3O4 is the only cobalt oxide species detected in all the supported catalysts. The oxidation of propene at low concentrations over selected cobalt oxide catalysts shows that the structural characteristics of the support influence on the catalytic performance.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071320v

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7219–7225

Titre :	Hydrogenation of vegetable oils over Pd on nanocomposite carbon catalysts
Type de document :	texte imprimé
Auteurs :	Irina L. Simakova, Auteur ; Olga A. Simakova, Auteur ; Anatoliy V. Romanenko, Auteur
Année de publication :	2008
Article en page(s) :	p. 7219–7225
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Vegetable oils--Hydrogenation Pd nanocomposite carbon catalysts
Résumé :	Catalytic hydrogenation of vegetable oils was studied over Pd nanocomposite carbon catalysts. The mesoporous structure of the carbon support was beneficial to achieve fast hydrogenation rates and the desired cis/trans ratio of monoenic products of edible oil hydrogenation. The preparation procedure developed for a slurry catalyst was successfully utilized for fixed bed applications. Industrial experience of Pd/nanocomposite carbon utilization in selective hydrogenation of edible and total hydrogenation of nonedible oils is described.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800663j

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7211–7218

Titre :	Study on the mechanism and kinetics of the thermal decomposition of Ni/Al layered double hydroxide nitrate
Type de document :	texte imprimé
Auteurs :	Liren Wang, Auteur ; Zhi Lü, Auteur ; Feng Li, Auteur
Année de publication :	2008
Article en page(s) :	p. 7211–7218
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Ni/Al layered double hydroxide nitrate Thermal decomposition Mass spectrometry
Résumé :	In the paper, the mechanism and kinetics of thermal decomposition of Ni/Al layered double hydroxide nitrate with a Ni/Al molar ratio of 3.0 (NiAl-LDH) were studied by thermogravimetry/differential thermal analysis coupled with mass spectrometry (TG/DTA−MS). The results indicated that the thermal decomposition of NiAl-LDH proceeds in three individual processes, i.e., removal of the physisorbed and interlayer water, dehydroxylation of the layers, and decomposition of the interlayer nitrate ions (denitration). The mechanism and kinetics of dehydroxylation and denitration, which take place simultaneously almost in the same region of temperatures, were separately achieved by only using MS data sets recorded at different heating rates. The dehytroxylation follows a two-dimensional diffusion-controlled mechanism with instantaneous nucleation represented by the first-order Avrami−Erofe’ev equation with an average activation energy of ca. 129.0 kJ·mol−1, while the denitration obeys a three-dimensional diffusion-controlled mechanism represented by the Zhuralev−Lesokin−Tempelman equation with an average activation energy of ca. 137.2 kJ·mol−1.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800609c

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7202–7210

Titre :	Effect of mixing and other operating parameters in sol-gel processes
Type de document :	texte imprimé
Auteurs :	Daniele L. Marchisio, Auteur ; Federica Omegna, Auteur ; Antonello A. Barresi, Auteur
Année de publication :	2008
Article en page(s) :	p. 7202–7210
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Sol-gel process Titanium dioxide synthesis Thermal treatments
Résumé :	In this work the effect of mixing on a sol−gel process is quantitatively investigated. Titanium dioxide synthesis from titanium tetra-isopropoxide is used as a test reaction. Solutions of titanium alkoxide in isopropyl alcohol and water in isopropyl alcohol are mixed in a special mixing device (i.e., vortex reactor) at different mixing rates, and the effect of mixing is quantified and compared with the effect of the other relevant operating parameters, namely the water to alkoxide, acid to alkoxide ratios, and alkoxide initial concentration. Dynamic light scattering, specific surface area measurement through nitrogen adsorption, X-ray diffraction, and field emission scanning electron microscopy are employed to determine particle size distribution, morphology, and crystallite size of the different particulate products (i.e., sols, gels, powders) obtained before and after thermal treatments under different synthesis conditions. A factorial design is used to plan the experimental campaign and results show that the role of mixing cannot be neglected. Moreover results show that mixing can be actively used to control the final product characteristics and must be taken into account when a process is transferred from the laboratory to the industrial scale. Eventually a scale-up criterion based on our previous work will be discussed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800217b

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7190–7201

Titre :	Enhanced gas-liquid mass transfer of an oscillatory constricted-tubular reactor
Type de document :	texte imprimé
Auteurs :	Nuno Reis, Auteur ; Ricardo N. Pereira, Auteur ; António A. Vicente, Auteur
Année de publication :	2008
Article en page(s) :	p. 7190–7201
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Gas-liquid flow--mass transfer Oscillating mesotube Tubular reactor
Résumé :	The mass transfer performance has been tested for gas−liquid flow in a new tubular reactor system, the oscillating mesotube (OMT), which features the oscillatory movement of fluid across a series of smooth constrictions located periodically along the vertical 4.4 mm internal diameter tube. The effect of the fluid oscillations (frequency, f, and center-to-peak amplitude, x0, in the range of 0−20 s−1 and 0−3 mm, respectively) on the overall volumetric mass transfer coefficient (kLa) has been tested by measuring the oxygen saturation levels with a fiber-optical microprobe (oxygen micro-optrode), and a mathematical model has been produced to describe the oxygen mass transport in the OMT. The oxygen mass transfer rates were about 1 order of magnitude higher (kLa values up to 0.16 s−1) than those values reported for gas−liquid contacting in a 50 mm internal diameter oscillatory flow reactor (OFR), for the same peak fluid oscillatory velocity, i.e., 2πfx0. This represents remarkable oxygen transfer efficiencies, especially when considering the very low mean superficial gas velocity involved in this work (0.37 mm s−1). The narrower constrictions helped to increase the gas fraction (holdup) by reducing the rise velocity of the bubbles. However, the extent of radial mixing and the detachment of vortex rings from the surface of the periodic constrictions are actually the main causes of bubbles retention and effective gas−liquid contacting and are, thus, responsible for the enhancement of kLa in the OMT.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8001588

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7184–7189

Titre :	Syngas production from catalytic partial oxidation of n-butane : comparison between incipient wetness and sol-gel prepared Pt/Al2O3
Type de document :	texte imprimé
Auteurs :	Rainer J. Bass, Auteur ; Timothy M. Dunn, Auteur ; Yu-Chuan Lin, Auteur
Année de publication :	2008
Article en page(s) :	p. 7184–7189
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	n-butane Catalytic partial oxidation Sol-gel catalyst Incipient wetness catalyst
Résumé :	Catalytic partial oxidation (CPO) of n-butane under autothermal condition was studied over both incipient wetness (IW) and sol−gel (SG) prepared Pt/Al2O3 catalysts. These catalysts gave different results, with SG Pt/Al2O3 producing more H2 and CO than IW Pt/Al2O3 under the same reaction conditions. The difference between these two may be attributed to the particle size of platinum: the observed Pt particle sizes on both freshly prepared and used SG Pt/Al2O3 was 50% smaller than those on IW Pt/Al2O3.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8007506

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7178–7183

Titre :	Benzene reduction by alkylation in a solid phosphoric acid catalyzed olefin oligomerization process
Type de document :	texte imprimé
Auteurs :	Tebogo M. Sakuneka, Auteur ; Reinier J. J. Nel, Auteur ; Arno de Klerk, Auteur
Année de publication :	2008
Article en page(s) :	p. 7178–7183
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Solid phosphoric acid Benzene Olefin oligomerization
Résumé :	A refinery with a solid phosphoric acid olefin oligomerization unit can reduce the benzene content of its motor-gasoline by co-feeding the benzene-containing material to that unit. It has been shown that benzene co-feeding has little disruptive impact on olefin oligomerization, and >80% benzene conversion to alkylated benzenes has been demonstrated during a commercial test run on an industrial unit. Benzene conversion is insensitive to reactor inlet temperature in the range of 160−180 °C and remains better than 80% at liquid hourly space velocities of up to 1.5 h−1. A high propene content in the olefinic feed promotes benzene alkylation, and although butene-rich feeds can be employed, benzene conversion is lower.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800672p

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7167–7177

Titre :	Kinetic and isotopic study of ethane dehydrogenation over a semicommercial Pt,Sn/Mg(Al)O catalyst
Type de document :	texte imprimé
Auteurs :	Anastasia Virnovskaia, Auteur ; Erling Rytter, Auteur ; Unni Olsbye, Auteur
Année de publication :	2008
Article en page(s) :	p. 7167–7177
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Ethane dehydrogenation Kinetic study Semicommercial Pt,Sn/Mg(Al)O catalyst
Résumé :	Mechanistic and kinetic information on the ethane dehydrogenation reaction over a semicommercial Pt,Sn/Mg(Al)O catalyst has been elucidated from catalytic testing and isotopic labeling experiments under reaction conditions close to those used in the commercial dehydrogenation process (C2H6/H2/H2O/inert = 10/1.5/2/32 or C2H6/H2/CO2/inert = 10/2/5/83, 600−630 °C reaction temperature, atmospheric pressure). From kinetic measurements, a negative dependence of the reaction rate in H2 and C2H4 partial pressures was observed, while the dependence on steam partial pressure was positive. Isotopic labeling experiments showed that the negative effect of H2 and C2H4 could not be attributed to the reverse reaction, but rather to competitive adsorption at the active sites for dehydrogenation. The observed reaction rate with respect to C2H6 was close to first order. By fitting the experimental data to the rate equation derived from the elementary steps of ethane dehydrogenation, the observed deviation from the first order could be explained by partial occupation of the surface by adsorbed surface species. Methane and ethyne were the main byproducts of the dehydrogenation reaction. Cofeed experiments with 13C12CH6/12C2H4 indicated that both methane and ethyne are produced via ethene, and not directly from ethane. D2/C2H6 cofeeding experiments revealed further that one H at the time is replaced with D in ethene, that addition of CO2 does not affect the H−D distribution in ethene and ethyne and that practically no H−D exchange takes place over the support. The activation energy of the dehydrogenation of ethane over the present catalyst has in a previous study been determined to 116 kJ/mol [Virnovskaia, A.; Morandi, S.; Rytter, E.; Ghiotti, G.; Olsbye, U. Characterization of Pt,Sn/Mg(Al)O Catalysts for Light Alkane Dehydrogenation by FT-IR Spectroscopy and Catalytic Measurements. J. Phys. Chem. C 2007, 111, 14732]. The apparent activation energy for ethene hydrogenation over the same catalyst could be determined to −40 kJ/mol in the temperature range 497−596 °C, indicating that in this temperature range the decrease in surface coverage with temperature overcompensates the increase of the rate constant of the rate determining step of the hydrogenation reaction.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800361a

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7161–7166

Titre :	Simultaneous hydrogenation of multiring aromatic compounds over NiMo catalyst
Type de document :	texte imprimé
Auteurs :	A. R. Beltramone, Auteur ; D. E. Resasco, Auteur ; W. E. Alvarez, Auteur
Année de publication :	2008
Article en page(s) :	p. 7161–7166
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Multi-ring aromatic compounds Hydrogenation NiMo catalyst
Résumé :	Hydrogenation of six model feeds containing three-, two-, and one-ring aromatic compounds was investigated to gain insights into the aromatic hydrogenation reaction chemistry over a commercial NiMo catalyst under practical reaction conditions. The hydrogenation reactivity of the aromatic compounds followed the following order: phenanthrene ∼ two-ring aromatics ≫ one-ring aromatic. Comparison with previous studies revealed that the relative reactivity of the aromatic compounds is strongly influenced by the nature of the catalyst. Multiple-component feed studies showed that phenanthrene and naphthalene strongly inhibited the tetralin hydrogenation rate; however, naphthalene and tetralin had no appreciable effect on phenanthrene conversion. Langmuir−Hinshelwood-type rate equations were used to describe the reaction kinetics with physically meaningful and well-identified parameter values. The inhibition was attributed to competitive adsorption and was described in the kinetic model by adsorption terms that were obtained from the multicomponent feed experiments.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8004258

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7154–7160

Titre :	Oxidative dimerization of phenol based on micromixing in single- and two-phase systems
Type de document :	texte imprimé
Auteurs :	Yoshihito Okubo, Auteur ; Hideyuki Higashimura, Auteur ; Kazuhiro Mae, Auteur
Année de publication :	2008
Article en page(s) :	p. 7154–7160
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Phenol Oxidative polymerization Microdroplets Single- and two-phase systems
Résumé :	It is an important technique to obtain target products with higher yields by controlling the reaction and mass transfer. In this work, we focused on molecular weight control in the oxidative polymerization of phenol. We attempted selective production of phenol dimers through the formation of microdroplets in both single- and two-phase systems. In a single-phase system, selectivity of dimers to polymers can be improved by rapidly mixing ingredients using a micromixer. Further, we clarified the conditions to utilize such microspace effects by comparing the initial reaction time constant with the mixing time constant by order-of-magnitude estimation. In a two-phase system, it was clarified that controlling of mass transfer by formation of microdroplets using a micromixer was effective in the control of consecutive elementary reactions though the dimer selectivity hardly changes and the effect of micromixing was limited.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800054n

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7147–7153

Titre :	Experimental study of O2-CO2 production for the oxyfuel combustion using a co-based oxygen carrier
Type de document :	texte imprimé
Auteurs :	Zhen-shan Li, Auteur ; Teng Zhang, Auteur ; Ning-sheng Cai, Auteur
Année de publication :	2008
Article en page(s) :	p. 7147–7153
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	O2-CO2 mixed gases Oxyfuel combustion Co-based oxygen carrier Fixed bed reactor
Résumé :	Production of O2−CO2 mixed gases for the oxyfuel combustion using a Co-based oxygen carrier packed in a fixed bed reactor was investigated. The reaction kinetics of CoO with O2 and the decomposition kinetics of Co3O4 in CO2 atmosphere at different temperatures were studied using thermogravimetric analysis (TGA). Both desorption and sorption processes exhibit a high reaction rate. Multiple sorption and desorption cycles indicated that Co-based oxygen carrier has high reactivity and cyclic stability. The results of X-ray diffraction indicated that Co-based oxygen carrier does not react with CO2 during the desorption stage, and this is especially important for oxyfuel combustion. The high temperature sorption process for production of O2−CO2 gas mixtures in a fixed bed reactor packed with Co-based oxygen carrier particles through air separation with carbon dioxide as the purge gas is investigated. Oxygen is absorbed, and heat is stored by the Co-based oxygen carrier particles with air being fed. An O2−CO2 stream can be obtained when the fixed bed is regenerated with carbon dioxide as the desorption gas. O2 fraction in the O2−CO2 gas mixtures can be controlled by adjusting the flow rate of CO2 regeneration gas. This Co-based oxygen carrier offers potential for further study in the O2−CO2 production for the oxyfuel coal combustion process.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071527o

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7141–7146

Titre :	Photodegradation of bisphenol A in the montmorillonite KSF suspended solutions
Type de document :	texte imprimé
Auteurs :	Y. X. Liu, Auteur ; X. Zhang, Auteur ; L. Guo, Auteur
Année de publication :	2008
Article en page(s) :	p. 7141–7146
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Montmorillonite KSF Heterogeneous system Bisphenol A
Résumé :	The commercially available montmorillonite KSF is utilized as efficient acidic catalyst in organic synthesis chemistry. In this study it is used as a photoactive reagent in a heterogeneous system. A series of experiments of the degradation of bisphenol A (BPA) as a model organic pollutant in montmorillonite KSF suspended solutions under UV−vis irradiation (metal halide lamp, λ ≥ 365 nm) were investigated. It is found that BPA could be effectively photodegraded in suspension. The BPA photodegradation is dependent on the pH of the solution and dosage of clay minerals, and it is more effective for BPA to be degraded at pH 4; the degradation rate of BPA increased with the concentration of clays in the range of 0.5 g/L to 5 g/L. The photodegradation rate of BPA is fitted well into the Langmuir−Hinshelwood equation. Results also indicate that the carboxylate and dissolved oxygen could efficiently enhance the degradation rate, and the role of carboxylate in accelerating the photodegradation of BPA follows the order: pyruvate > oxalate > citrate.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800169c

[article]
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7131–7140

Titre :	Dilute acid hydrolysis of loblolly pine : a comprehensive approach
Type de document :	texte imprimé
Auteurs :	Teresita Marzialetti, Auteur ; Mariefel B. Valenzuela-Olarte, Auteur ; Carsten Sievers, Auteur
Année de publication :	2008
Article en page(s) :	p. 7131–7140
Note générale :	Chemical engineering
Langues :	Anglais (eng)
Mots-clés :	Acid hydrolysis Loblolly pine Monosaccharides
Résumé :	A comprehensive study of the acid hydrolysis of the softwood species, Loblolly pine (Pinus taeda), using different hydrolysis conditions is presented. The effect of the type of acid, pH, reaction temperature, and reaction time on hydrolysis products such as monosaccharides (mannose, glucose, galactose, xylose, and arabinose) and the subsequent degradation products, 5-hydroxymethyl-2-furaldehyde (HMF) and 2-furaldehyde (furfural) is reported using a batch reactor. Trifluoroacetic acid (TFA) is found to yield the highest amount of overall soluble monosaccharides (∼70% yield from the hemicelluloses fraction) at 150 °C at pH 1.65. The mineral acids (HCl, H2SO4, HNO3, and H3PO4) gave a slightly lower yield of monosaccharides from hydrolyzed hemicellulose (∼60%). At 200 °C, cellulose is hydrolyzed by the mineral acids as evidenced by higher levels of solid dissolution and higher soluble hexose (relative to pentose) yields. Larger amounts of degradation products are also noted at higher temperatures. Furthermore, an increased amount of HMF and furfural is noted in the liquid product as compared to lower temperatures. TFA was found to be the most “gentle” acid, leading to limited monosaccharide degradation among the acids used. The presence of soluble oligosaccharides in solution after hydrolysis was confirmed by applying a secondary acid hydrolysis to the solid-free liquid hydrolysate. Good closure of mass balances was possible using total organic carbon (TOC) analysis.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800455f

Industrial & engineering chemistry research / Paul, Donald R. . Vol. 47 N°19

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