Catalogue en ligne Bibliothèque Ecole Nationale Polytechnique d'Alger

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10086–10092

Titre :	Hydrodynamic effects in scaled-down hydrocracking of iron-based fischer-tropsch wax
Type de document :	texte imprimé
Auteurs :	Werner van der Merwe, Auteur ; Dylan Loudon, Auteur ; Dieter Leckel, Auteur
Année de publication :	2009
Article en page(s) :	p. 10086–10092
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Hydrodynamic--Effects Iron Wax
Résumé :	Iron-based low-temperature Fischer−Tropsch (LTFT) wax was hydrocracked in upflow and downflow mode of operation using fixed-bed bench-scale and pilot-scale reactors. Heavy paraffin conversion was higher in the upflow mode whereby lower diesel selectivities were observed. It was also shown that the diesel properties are a function of the mode of operation. The results indicate the presence of macrokinetic (hydrodynamic) limitations on the overall hydrocracking rate that is present due to the comparatively low liquid superficial velocity. The higher hydrocracking efficiency in the upflow mode is likely due to complete particle wetting (compared to the partial wetting in the downflow mode) that enhances both external and internal mass transfer of the liquid phase reagent. The results highlight the danger of scaled-down reactors that might not be representative of industrial operation.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800894w

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10080–10085

Titre :	Perspective for extended group-contribution methods for the prediction of activity coefficients accounting for sterical effects. Linking UNIFAC and the group vector space method
Type de document :	texte imprimé
Auteurs :	Stephan Machefer, Auteur ; Martin Grasemann, Auteur ; Klaus Schnitzlein, Auteur
Année de publication :	2009
Article en page(s) :	p. 10080–10085
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Vector space Wen, X. Qiang, Y.
Résumé :	Group contribution methods for the calculation of an activity coefficient such as UNIFAC (universal factorial activity coefficient) currently do not take into account sterical effects. Consequently one of the major deficiencies of such methods is their inability to resolve isomeric systems and their often insufficient accuracy for systems including molecules of very different size. In this paper an approach is presented by which sterical information can be implemented into those methods by means of a modified group vector space (GVS) procedure. (Wen, X.; Qiang, Y. Group Vector Space method for estimating melting and boiling points of organic compounds. Ind. Eng. Chem. Res. 2002, 41, 5534−5537.) Exemplary calculations with UNIFAC/GVS underline the potential of this new approach resulting in a perspective for substantially improved group contributions methods with a wider range of applicability and even more reliable predictive performance.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800980m

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10076–10079

Titre :	Superfast transesterification of triolein using dimethyl ether and a method for high-yield transesterification
Type de document :	texte imprimé
Auteurs :	Hidetoshi Kuramochi, Auteur ; Kouji Maeda, Auteur ; Masahiro Osako, Auteur
Année de publication :	2009
Article en page(s) :	p. 10076–10079
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Triolein--Transesterification Dimethyl Ether
Résumé :	Superfast transesterification of triolein (a biodiesel feedstock model) was achieved in the presence of liquefied dimethyl ether using the co-solvent effect and low viscosity. Furthermore, a method for higher ester yield, in which methanol was additionally introduced into the reaction system immediately before the beginning of phase separation due to byproduct glycerin to maintain the reaction system in a homogeneous state, was proposed. This method led to superfast and high-yield transesterification with a yield exceeding 96% at 3 min.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800513j

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10071–10075

Titre :	Extractant selection strategy for solvent-Impregnated resins in fermentations
Type de document :	texte imprimé
Auteurs :	Corjan van den Berg, Auteur ; Mark Roelands, Auteur ; Paul Bussmann, Auteur
Année de publication :	2009
Article en page(s) :	p. 10071–10075
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Solvent-Impregnated
Résumé :	The application of extractants in whole-cell biocatalysis can have a positive impact on industrial fermentations, in terms of productivity, total amount of product produced, and cell growth. When a product is continuously removed from the microorganism surroundings, product inhibition will be diminished. The strategy is exemplified using phenol as the product and the extractant is selected for solvent-impregnated resins, which can prevent emulsification problems that are commonly encountered in in situ extractive recovery of fermentation products. A systematic approach for selection of superior extractants in whole-cell biocatalysis is discussed in this paper. Three criteria are taken into account, namely, extractant toxicity (log Po/w values), product selectivity, and extractant regeneration.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800973y

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p.10064–10070

Titre :	Breakthrough characteristics of reformate desulfurization using ZnO sorbents for logistic fuel cell power systems
Type de document :	texte imprimé
Auteurs :	HongYun Yang, Auteur ; Ryan Sothen, Auteur ; Donald R. Cahela, Auteur
Année de publication :	2009
Article en page(s) :	p.10064–10070
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Reformate Desulfurization ZnO
Résumé :	Sulfur breakthrough behaviors during reformate desulfurization were investigated using a novel ZnO-based sorbent with minimized mass transfer resistance. The presence of CO, CO2, or water affected the breakthrough characteristics of H2S and carbonyl sulfide (COS). CO and CO2 did not significantly affect the reaction between H2S and ZnO, but they reacted with H2S to form COS, which cannot be efficiently removed by ZnO. The mechanisms of COS formation via two different pathways were also investigated. CO reacted with H2S to form COS homogeneously; CO2 reacted with H2S heterogeneously on the sulfide surface. COS formation by CO and CO2 was suppressed by H2 and water. Water also severely hindered the reaction between ZnO and H2S and significantly decreased H2S breakthrough time. At low water concentrations, sulfur breakthrough was determined by the homogeneous COS formation; at high water concentrations, it was controlled by H2S breakthrough. Capacity loss due to COS formation and adsorption of water was also observed. Novel sorbent and process designs are required to improve the desulfurization performance.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8008617

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10053–10063

Titre :	In Vivo Simulations of the Intravenous Dynamics of Submicrometer Particles of pH-Responsive Cationic Hydrogels in Diabetic Patients
Type de document :	texte imprimé
Auteurs :	Terry G. Farmer Jr., Auteur ; Thomas F. Edgar, Auteur ; Nicholas A. Peppas, Auteur
Année de publication :	2009
Article en page(s) :	p. 10053–10063
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Dynamics Submicrometer Simulations
Résumé :	A mathematical model describing glucose-dependent pH swelling and insulin release is developed for pH-sensitive cationic hydrogels in which glucose oxidase and catalase have been immobilized and insulin imbibed. Glucose-based swelling and insulin release are simulated for intravenously injected particles at various design conditions. The effects of particle size, the number of injected particles, insulin loading, enzyme loading, monomer functional group loading and pKa, and hydrogel cross-linking ratio on insulin release and glucose sensitivity are investigated to optimally design the device for use. Increased insulin infusion is shown to result from increasing the number of circulating gels, increasing the collapsed particle size, or decreasing the cross-linking ratio of the system. Release duration is shown to be dependent only upon the particle size and the achievable diffusion coefficient of the system. Glucose sensitivity, as measured by gluconic acid production and by the system pH, is a function of glucose oxidase loading and the concentration and pKa of the monomer used in the hydrogel. The necessary submicrometer particle size results in very rapid device insulin depletion. When the device is designed without considering constraints, the resulting release profile resembles that of an on/off switching mechanism. Future work will focus on simulations of swelling and release when the device is implanted in an alternative administration site.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie070957b

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10041–10052

Titre :	Addition of the hydrogen sulfide group to the PPR78 model (Predictive 1978, Peng–Robinson equation of state with temperature dependent kij calculated through a group contribution method)
Type de document :	texte imprimé
Auteurs :	Romain Privat, Auteur ; Mutelet Fabrice, Auteur ; Jaubert, Jean-Noël, Auteur
Année de publication :	2009
Article en page(s) :	p. 10041–10052
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Hydrogen Sulfide PPR
Résumé :	In 2004, we started to develop the PPR78 model which is a group contribution method aimed at estimating the temperature dependent binary interaction parameters (kij(T)) for the widely used Peng–Robinson equation of state. In our previous papers, 13 groups were defined: CH3, CH2, CH, C, CH4 (methane), C2H6 (ethane), CHaro, Caro, Cfused_aromatic_rings, CH2,cyclic, CHcyclic or Ccyclic, CO2, and N2. It was thus possible to estimate the kij for any mixture containing alkanes, aromatics, naphthenes, carbon dioxide, and nitrogen whatever the temperature. In this study, the PPR78 model is extended to systems containing hydrogen sulfide. To do so, the group H2S was added. From a general overview on the results obtained from the whole constituted experimental data bank, one can see that the PPR78 model is able to quite accurately predict the behavior of the systems containing H2S.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800799z

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10034–10040

Titre :	Thermal cracking of JP-10 under pressure
Type de document :	texte imprimé
Auteurs :	Yan Xing, Auteur ; Fang, Wenjun, Auteur ; Wenjie Xie, Auteur
Année de publication :	2009
Article en page(s) :	p. 10034–10040
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Thermal Cracking
Résumé :	Thermal cracking of a high density hydrocarbon fuel, JP-10 (exo-tetrahydrodicyclopentadiene), was studied on a batch reactor under different pressures. The effluent was cooled and collected at room temperature and atmospheric pressure. The gaseous and liquid components were quantitatively determined by gas chromatography and gas chromatography−mass spectrometry, respectively. The conversion of JP-10 has relatively low value at atmospheric pressure and increases under pressure. With an increase of the pressure, the relative content of ethene or propene decreases and that of methane, ethane, or propane increases simultaneously. In the liquid products, cyclopentane, cyclopentene, 1,3-cyclopentadiene, and cis-bicyclo[3.3.0]oct-2-ene are found to be major components. Substituted cyclopentene, benzene, toluene, and naphthalene are also observed under high pressures and temperatures. A probable mechanism of the thermal cracking of JP-10 is proposed to explain the product distribution. The process of isomerization might be dominating for liquid product formation during the thermal cracking under elevated pressure.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801128f

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10027–10033

Titre :	Equilibrium studies on enantioselective liquid-liquid Amino Acid extraction using a cinchona alkaloid extractant
Type de document :	texte imprimé
Auteurs :	Boelo Schuur, Auteur ; Jozef G.M. Winkelman, Auteur ; Hero J. Heeres, Auteur
Année de publication :	2009
Article en page(s) :	p. 10027–10033
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Liquid-Liquid Amino Acid
Résumé :	The enantioselective extraction of aqueous 3,5-dinitrobenzoyl-R,S-leucine (AR,S) by a cinchona alkaloid extractant (C) in 1,2-dichloroethane was studied at room temperature (294 K) in a batch system for a range of intake concentrations (10−4−10−3 mol/L) and pH values (3.8−6.6). The experimental data were described by a reactive extraction model with a homogeneous organic phase reaction of AR,S with C. Important parameters of this model were determined experimentally. The acid dissociation constant, Ka, of AR,S was (1.92 ± 0.07) × 10−4 mol/L. The physical distribution coefficient of AR,S between the organic and aqueous phase was 8.04 ± 0.39. The equilibrium constants of the organic phase complexation reaction were (9.31 ± 0.76) × 104 L/mol and (2.71 ± 0.76) × 104 L/mol for the S- and R-enantiomers, respectively. With these parameters an optimum performance factor, PF, of 0.19 was predicted. The PF was independent of the pH provided that pH ≫ pKa. The model was verified experimentally with excellent results (±7.9%).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800668e

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10020–10026

Titre :	Separation of Ammonia/Water/Sodium Hydroxide mixtures using reverse osmosis membranes for low temperature driven absorption chillers
Type de document :	texte imprimé
Auteurs :	Simona Steiu, Auteur ; Joan Carles Bruno, Auteur ; Alberto Coronas, Auteur
Année de publication :	2009
Article en page(s) :	p. 10020–10026
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Ammonia/Water/Sodium Hydroxide--Separation Mixtures
Résumé :	The conventional working fluids used in absorption chillers (water/lithium bromide and ammonia/water) present several disadvantages that limit their effective application. Recently, some works have reported the addition of NaOH to the ammonia/water working pair to improve the separation of ammonia in the generator, reducing the chiller driving temperature by taking advantage of the common ion effect. However, the presence of NaOH in the absorber has a negative impact on the absorption process. This study analyzes the technical viability of separating NaOH from ammonia/water/NaOH mixtures by using reverse osmosis membranes to incorporate this separation method into future chiller designs that work with these mixtures. The concentration range analyzed covers the solution concentration values of interest for absorption chiller applications (approximate 0.02−0.05 mass fraction of NaOH and 0.3 mass fraction of NH3). The results obtained show that, by using an in-series configuration of the modules, reverse osmosis technology is suitable for separating NaOH from the ternary mixtures studied.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8004012

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10009–10019

Titre :	Fault detection and isolation for nonlinear process systems using asynchronous measurements
Type de document :	texte imprimé
Auteurs :	Charles W. McFall, Auteur ; David Muñoz de la Peña, Auteur ; Ben Ohran, Auteur
Année de publication :	2009
Article en page(s) :	p. 10009–10019
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	(FDI) scheme Isolation for Nonlinear Process Systems
Résumé :	This work addresses the problem of fault detection and isolation for nonlinear processes when some process variable measurements are available at regular sampling intervals and the remaining process variables are measured at an asynchronous rate. First, a fault detection and isolation (FDI) scheme that employs model-based techniques is proposed that allows for the isolation of faults. The proposed FDI scheme provides detection and isolation of any fault that enters into the differential equation of only synchronously measured states and grouping of faults that enter into the differential equation of any asynchronously measured state. For a fully coupled process system, fault detection occurs shortly after a fault takes place, and fault isolation, limited by the arrival of asynchronous measurements, occurs when asynchronous measurements become available. Fault-tolerant control methods with a supervisory control component are then employed to achieve stability in the presence of actuator failures using control system reconfiguration. Numerical simulations of a polyethylene reactor are performed to demonstrate the applicability and performance of the proposed fault detection and isolation and fault-tolerant control method in the presence of asynchronous measurements.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801056y

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9996–10008

Titre :	Enhanced process comprehension and statistical analysis for slow-varying batch processes
Type de document :	texte imprimé
Auteurs :	Zhao, Chunhui, Auteur ; Wang, Fuli, Auteur ; Gao, Furong, Auteur
Année de publication :	2009
Article en page(s) :	p. 9996–10008
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Statistical analysis
Résumé :	Under the influence of various exterior factors, batch processes commonly involve normal slow variations over batches, in which the changing underlying behaviors make their modeling and monitoring a greater challenge. Having realized the problems associated with the commonly adopted adaptive methods, in the present work, our biggest concern is how to minimize the efforts for long-term model updating adjustment and simultaneously maintain their validity as permanently as possible once the initial models are built. It is implemented from the viewpoint of between-batch relative changes, which are regular with process evolution and conform to certain evolving rule and statistical characteristics. First, difference subspace is constructed by calculating the between-batch difference trajectories, which represent the batchwise relative changes resulting from the slow-varying behaviors. Then their variability along batch direction is addressed and analyzed in the difference subspace using ICA-PCA two-step feature extraction, which reveals the evolving rule and statistical characteristics of slow variations. In this way, the mode of normal slow changes is extracted, trained, and modeled, which, thus, endows the initial monitoring system with adaptive competency to slow-varying behaviors. Therefore, it is less sensitive to normal slow variations, which eases the excessive dependency of monitoring performance on updating and, thus, decreases the risk of false adaptation to process disturbances. Despite the simplicity of the proposed idea and algorithm, the performance it achieves in the case studies indicates that it is smart and competitive as a feasible solution to analyze and monitor the regular slow-varying characteristics.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800643d

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p.9983–9995

Titre :	Analysis of extractive distillation with mathematical programming
Type de document :	texte imprimé
Auteurs :	Abdulfatah M. Emhamed, Auteur ; Barbara Czuczai, Auteur ; Endre Rev, Auteur
Année de publication :	2009
Article en page(s) :	p.9983–9995
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Mathematical
Résumé :	Extractive distillation processes are investigated by optimization. The proposed MINLP model and optimization tool are able to analyze complex distillation processes. Application of the method is demonstrated on two different extractive processes: acetone/methanol mixture using water as heavy solvent and ethanol/water mixture using methanol as light solvent. The two systems are analyzed separately; the analysis is performed both from technological and economical aspects. The optimal structures are found widely independent of the weights of different cost parts. Thus, small changes in the economic environment will not alter the optimal configuration.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071556z

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9971–9982

Titre :	Constructive molecular weight control of continuous homopolymer reactors
Type de document :	texte imprimé
Auteurs :	Pablo González, Auteur ; Jesus Alvarez, Auteur
Année de publication :	2009
Article en page(s) :	p. 9971–9982
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Molecular Homopolymer
Résumé :	In this work, the problem of controlling (possibly open-loop unstable) continuous free-radical solution polymer reactors with continuous measurements of temperature, level and flows and discrete-delayed (DD) measurements of molecular weight (MW) is addressed. On the basis of physical insight and the relative degrees and detectability structure of the reactor system, a muti-input−multi-output (MIMO) interlaced observer-control design is performed within a constructive framework, yielding a linear-decentralized control scheme with volume, temperature, and monomer components driven by continuous-instantaneous measurements, and a MW component driven by DD measurements. The scheme has reduced modeling requirements and conventional-like tuning guidelines drawn from stability considerations. The proposed approach is illustrated and tested with a representative example through simulations.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071361r

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9957–9970

Titre :	More on completion time algorithms for intermediate storage tanks in multiproduct batch process scheduling using matrix representation
Type de document :	texte imprimé
Auteurs :	Amir Shafeeq, Auteur ; M. I. Abdul Mutalib, Auteur ; K. A. Amminudin, Auteur
Année de publication :	2009
Article en page(s) :	p. 9957–9970
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Algorithms for Intermediate Storage
Résumé :	In batch process scheduling, the introduction of intermediate storage tanks between process stages result in increasing the efficiency and productivity of the process. The main purpose of this is to minimize the process completion time, i.e. makespan. However, it is important to determine the right number and respective locations of the intermediate storage to ensure optimal investment and operational cost. The generally adopted transfer policies for handling intermediate storage tanks in batch processes are unlimited intermediate storage (UIS) and finite intermediate storage (FIS). In this work, new completion time algorithms for UIS and FIS transfer policies are proposed using matrix representation. The objective of the proposed approach is to calculate the makespan for all possible production sequences for given batch product recipes while at the same time determining the number and location of intermediate storage tanks required. With the assumptions that the intermediate storage could be used to store any intermediate product, the method is verified against the Gantt chart method and the results agreed well. A number of different product recipes are analyzed using a developed computer code. This enables the proposed algorithms to produce solution options for large size batch scheduling problems.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800068j

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9941–9956

Titre :	Efficient tool for the scheduling of multiproduct pipelines and terminal operations
Type de document :	texte imprimé
Auteurs :	Diego C. Cafaro, Auteur ; Jaime Cerdá, Auteur
Année de publication :	2009
Article en page(s) :	p. 9941–9956
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Pipelines Mixed-integer linear programming (MILP)
Résumé :	This paper addresses the problem of scheduling a transmission pipeline carrying several petroleum products from a single oil refinery to a unique distribution center over a monthly horizon. The proposed approach is based on a very efficient mixed-integer linear programming (MILP) continuous-time formulation that is capable of determining the optimal pipeline batch sequence and lot sizes as well as the schedule of lot injections in the line and the timing of product deliveries to the distribution terminal. Moreover, the MILP model rigorously accounts for customer product demands on a daily basis, key terminal operations like lot settling periods for quality control tasks, and a predefined set of alternative lot sizes to get better control of tank availability. The approach also does not require the division of pipeline segments into a number of single-product packs of known capacities since the volume scale is also handled in a continuous manner. Results found for several examples involving the schedule of a real-world single-source single-destination multiproduct pipeline under different operational scenarios show that the proposed method leads to better pipeline schedules than previous approaches in a more rigorous way and at much lower computational cost.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071630d

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9931–9940

Titre :	Controllability analysis and decentralized control of a wet limestone flue gas desulfurization plant
Type de document :	texte imprimé
Auteurs :	A. L. Villanueva Perales, Auteur ; F. J. Gutiérrez Ortiz, Auteur ; P. Ollero, Auteur
Année de publication :	2009
Article en page(s) :	p. 9931–9940
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Gas desulfurization (WLFGD) plants
Résumé :	Presently, decentralized feedback control is the only control strategy used in wet limestone flue gas desulfurization (WLFGD) plants. Proper tuning of this control strategy is becoming an important issue in WLFGD plants because more stringent SO2 regulations have come into force recently.(3) Controllability analysis is a highly valuable tool for proper design of control systems, but it has not been applied to WLFGD plants so far. In this paper a decentralized control strategy is designed and applied to a WLFGD pilot plant taking into account the conclusions of a controllability analysis. The results reveal that good SO2 control in WLFGD plants can be achieved mainly because the main disturbance of the process is well-aligned with the plant and interactions between control loops are beneficial to SO2 control.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800801a

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9925–9930

Titre :	Simplified estimation of regeneration energy of 30 wt % sodium glycinate solution for carbon dioxide absorption
Type de document :	texte imprimé
Auteurs :	Ho-Jun Song, Auteur ; Seungmoon Lee, Auteur ; Kwinam Park, Auteur
Année de publication :	2009
Article en page(s) :	p. 9925–9930
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Sodium glycinate Carbon dioxide
Résumé :	A simple method for estimating the regeneration energy of CO2 absorption was devised. The regeneration energy of a 30 wt % sodium glycinate (SG) solution was calculated by the summation of the enthalpy of reaction, the sensible heat and the heat of vaporization. Each form of heat energy was determined experimentally. Solubilities of carbon dioxide in the SG solution was determined by gas chromatography (GC) analysis for the gas phase with the help of a virial equation for the liquid phase in the temperature range of 40−120 °C. Heat capacity of the solution was measured by a differential scanning calorimeter (DSC) and was used to calculate sensible heat. The heat of vaporization was evaluated by applying the Clausius−Clapeyron equation to 20 data points of vapor pressure. All of the experiments were carried out with either a 30 wt % aqueous solution of SG or the same concentration of monoethanolamine (MEA). Regeneration energy of the SG solution was found to be higher than that of the MEA solution by about 1000 kJ/kg of CO2. From the CO2 solubility data it was observed that SG had a higher capacity to absorb carbon dioxide than MEA even at the regeneration temperature (120 °C). In addition, the 30 wt % basis SG demonstrated a reduction in cyclic capacity at this regeneration temperature. So, our main effort is to establish a reasonable method for estimating CO2 absorbent regeneration energy along with the regeneration energy of 30 wt % aqueous solutions of SG.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8007117

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9919–9924

Titre :	Effect of anion on gas separation performance of polymer−room-temperature Ionic liquid composite membranes
Type de document :	texte imprimé
Auteurs :	Jason E. Bara, Auteur ; Douglas L. Gin, Auteur ; Richard D. Noble, Auteur
Année de publication :	2009
Article en page(s) :	p. 9919–9924
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Gas Separation Performance of Polymer photopolymerization
Résumé :	Composite gas separation membranes were fabricated by photopolymerization of a room-temperature ionic liquid (RTIL) monomer in the presence of 20 mol % of nonpolymerizable RTILs with various anions. The solid, composite membranes contained polymer-bound cations, “free” cations, and “free” anions. The composite materials exhibit no phase separation between these components. The permeabilities of CO2, N2, and CH4 in these poly(RTIL)−RTIL composites were observed to increase by 2−5 times relative to those in the neat poly(RTIL) without a “free” RTIL component. These largely increased permeabilities resulted in CO2/N2 and CO2/CH4 ideal separation selectivities that were only slightly diminished relative to the poly(RTIL) without a “free” RTIL. When viewed on “Robeson plots”, poly(RTIL)−RTIL composites are shown to be more favorable for CO2/N2 separation than CO2/CH4. Poly(RTIL)−RTIL composites are highly tunable materials with excellent promise as gas separation membranes.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801019x

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9913–9918

Titre :	Solid-state NMR characterization of silicon nitride bonded silicon carbide refractories
Type de document :	texte imprimé
Auteurs :	Zoran D. Zujovic, Auteur ; Ronny Etzion, Auteur ; James B. Metson, Auteur
Année de publication :	2009
Article en page(s) :	p. 9913–9918
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Silicon Nitride X-ray
Résumé :	Solid-state 29Si NMR spectroscopy and X-ray diffraction have been used to analyze commercial samples of silicon nitride bonded silicon carbide (SNBSC) refractories. Spectra of samples before and after exposure to aluminum electrolysis conditions from the peripheral and core parts of as manufactured SNBSC bricks from two different refractory producers are presented. The quantitative analysis of SiC/Si3N4 and α-Si3N4/β-Si3N4 using NMR is complicated due to the fact that SNBSC can contain paramagnetic impurities. Thus, from the NMR data, these ratios can only be tentatively estimated. It is shown that in order to achieve a comprehensive understanding of the microstructure of SNBSC materials, a combination of NMR and X-ray diffraction methods should be applied.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800759c

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9903–9912

Titre :	Nanostructure Iron(III)-zirconium(IV) binary mixed oxide : synthesis, characterization, and physicochemical aspects of arsenic(III) sorption from the aqueous solution
Type de document :	texte imprimé
Auteurs :	Kaushik Gupta, Auteur ; Krishna Biswas, Auteur ; Uday Chand Ghosh, Auteur
Année de publication :	2009
Article en page(s) :	p. 9903–9912
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Iron(III) zirconium(IV) mixed oxide (NHIZO) X-ray diffraction (XRD) scanning electron microscopy (SEM)
Résumé :	Characterization of synthetic Fe(III)−Zr(IV) mixed oxide (NHIZO) by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses confirmed the material as agglomerated nanocrystallite particles (16−21 nm) which was used for As(III) sorption from water. The optimum pH and equilibrium time (As(III) concentrations (mgL−1), 5.0 and 10.0; NHIZO dose, 2 g·L−1; temperature, 303 K) were 7.0 ± 0.2 and 2.0 h, respectively. The kinetic and equilibrium data described, respectively, the pseudo-second-order equation and the Langmuir as well as the Redlich−Peterson isotherm models very well. The Langmuir capacity was 65.5 ± 1.0 mg·g−1 at 303 K, which increased with increasing temperature. The positive enthalpy (ΔH°) and negative free energy (ΔG°) changes indicated the endothermic and spontaneous nature of the reaction, respectively. The sorption energy (4.64−5.20 kJ·mol−1) and Fourier transform infrared (FTIR) analyses suggested physissorption of As(III) by NHIZO. The sorbed arsenic could be desorbed (∼80%) by 2.0 M alkali. The toxicity leaching characteristic procedure test marked As(III)−NHIZO as nonhazardous waste.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8002107

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9896–9902

Titre :	Structure and properties of tough thermoplastic starch modified with polyurethane microparticles
Type de document :	texte imprimé
Auteurs :	Qiangxian Wu, Auteur ; Zhengshun Wu, Auteur ; Huafeng Tian, Auteur
Année de publication :	2009
Article en page(s) :	p. 9896–9902
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Thermoplastic Polyurethane
Résumé :	Aged thermoplastic starch (TPS), plasticized with hydrophilic plasticizers such as glycerol, shows brittle property. It is critical to develop tough TPS without using hydrophilic plasticizers. In this work, polyurethane prepolymer (PUP) was synthesized and mixed reactively with TPS in an intensive mixer to prepare modified TPS. Structural and morphological analyses showed that polyurethane (PU) microparticles were formed in situ and dynamically cross-linked to the starch matrix through urethane linkages. The modified TPS without hydrophilic plasticizer become tough. The elastic polyol soft segments in PU played the role of impact modifier, improving the toughness of the modified TPS. Almost 100% of PU was cross-linked to starch, indicating high efficiency of the modification. Formation of multifunctional PU microparticles was essential to achieve the high reaction efficiency. The dynamically cross-linking modification is a novel, green, and efficient method for preparing tough TPS.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801005w

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9889–9895

Titre :	Next-generation nonparticulate dry nonwoven pad for chemical warfare agent decontamination
Type de document :	texte imprimé
Auteurs :	Seshadri S. Ramkumar, Auteur ; Adam H. Love, Auteur ; Utkarsh R. Sata, Auteur
Année de publication :	2009
Article en page(s) :	p. 9889–9895
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Materials -- decontamination
Résumé :	New, nonparticulate decontamination materials promise to reduce both military and civilian casualties by enabling individuals to decontaminate themselves and their equipment within minutes of exposure to chemical warfare agents or other toxic materials. One of the most promising decontaminating materials has been developed using a needle-punching nonwoven process to construct a nonparticulate composite fabric of multiple layers, including an inner layer of activated carbon fabric, which is well-suited for the decontamination of both personnel and equipment. This paper describes the development of a composite nonwoven pad and compares efficacy test results for this pad with results from testing other decontamination systems. The efficacy of the dry nonwoven fabric pad was demonstrated specifically for decontamination of the chemical warfare blister agent bis(2-chloroethyl)sulfide (HD or sulfur mustard). Gas chromatography/mass spectroscopy (GC/MS) results indicate that the composite fabric was capable of significantly reducing the vapor hazard from mustard liquid absorbed into the nonwoven dry fabric pad. The mustard adsorption efficiency of the nonwoven pad was significantly higher than that of particulate activated carbon and was similar to the currently fielded U.S. military M291 kit. The nonwoven pad has several advantages over other materials, especially its nonparticulate, yet flexible, construction. This composite fabric was also shown to be chemically compatible with potential toxic and hazardous liquids, which span a range of hydrophilic and hydrophobic chemicals, including a concentrated acid, an organic solvent, and a mild oxidant (bleach).
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801223b

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9882–9888

Titre :	Banagrass vs eucalyptus wood as feedstocks for metallurgical biocarbon production
Type de document :	texte imprimé
Auteurs :	Takuya Yoshida, Auteur ; Scott Q. Turn, Auteur ; Russell S. Yost, Auteur
Année de publication :	2009
Article en page(s) :	p. 9882–9888
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Charcoal--production
Résumé :	Excessive emissions of fossil CO2 are known to be a primary cause of global climate change. Emissions from the iron and steel-making industries account for 5−6% of global fossil CO2 emissions. Biocarbon (i.e., charcoal) could be used to replace the coal currently employed to smelt iron ore and thereby reduce fossil CO2 emissions. In Brazil, Eucalyptus wood charcoal is used to smelt iron ore, but there is interest in the use of charcoal produced from other biomass feedstocks. Banagrass, a variety of elephantgrass (Pennisetum purpureum, Schum.), which produces near-record amounts of biomass, is a promising biomass candidate for charcoal production in Brazil and elsewhere. In this paper we describe results of charcoal production from banagrass of different ages and states of demineralization. Mature banagrass provides the highest yields of biocarbon. In addition to its maturity, the structure of the feedstock strongly influences the fixed-carbon yield. Our results indicate that banagrass may be preferred to Eucalyptus wood as a promising feedstock for metallurgical biocarbon production.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801123a

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9878–9881

Titre :	Kinetics of the reaction of hydrated lime with SO2 at low temperatures : effects of the presence of CO2, O2, and NOx
Type de document :	texte imprimé
Auteurs :	Liu, Chiung-Fang, Auteur ; Shih, Shin-Min, Auteur
Année de publication :	2009
Article en page(s) :	p. 9878–9881
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	sulfation--hydrated lime
Résumé :	The effects of the presence of CO2, O2, and NOx in the flue gas on the kinetics of the sulfation of hydrated lime at low temperatures were studied using a differential fixed-bed reactor. When O2 and NOx were not present together the reaction kinetics was about the same as that under gas mixtures containing SO2, H2O, and N2 only. When both O2 and NOx were present, sulfation of hydrated lime was greatly enhanced, forming a large amount of calcium sulfate in addition to calcium sulfite. Sulfation of hydrated lime was well described by the surface coverage model, despite the gas-phase conditions being different. Relative humidity is the major factor affecting the reaction, and its effect was more marked when both O2 and NOx were present. The kinetic model equations obtained in this work can be used to describe the sulfation of hydrated lime in the low-temperature dry and semidry flue gas desulfurization processes with or without an upstream NOx removal unit.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801105s

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9871–9877

Titre :	Desulfurization characteristics of waste cement particles as a sorbent in dry desulfurization
Type de document :	texte imprimé
Auteurs :	Jiawei Wu, Auteur ; Atsushi Iizuka, Auteur ; Kazukiyo Kumagai, Auteur
Année de publication :	2009
Article en page(s) :	p. 9871–9877
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Sulfur--Characteristics--Desulfurization
Résumé :	Dry desulfurization characteristics of waste cement particles were examined with laboratory-scale experimental apparatus based on the weight change of the sample exposed to a gas flow containing SO2. The waste cement particles, a byproduct of recycling aggregates from waste concrete, are fine particles with diameters ranging from 10 to 200 μm and an average diameter of 105 μm. The effects of the operation parameters, i.e., the reaction temperature (650−950 °C), SO2 concentration (61−1543 ppm), oxygen concentration (0−10%), NO2 concentration (0−500 ppm), absolute humidity (0−15000 ppm), and particle size (10−200 μm), on the desulfurization performance were investigated. The desulfurization rates were found to depend on the 1.26th order of the SO2 concentration and to slightly depend on the absolute humidity and the particle size, but they were almost independent of the concentrations of oxygen and NO2 in the gas flow. Arrhenius type temperature dependence was observed up to 850 °C with activation energy of 12 kJ/mol. The observed dry desulfurization rates of the waste cement particle were almost equivalent to those of the conventional sorbents such as limestone and calcium hydroxide. Therefore, it is confirmed that the waste cement particles could be applicable in dry desulfurization as an inexpensive sorbent derived from wastes.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie8009654#afn1

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9862–9870

Titre :	Reaction from dimethyl carbonate (DMC) to diphenyl carbonate (DPC). 2. : kinetics of the reactions from DMC via methyl phenyl carbonate to DPC
Type de document :	texte imprimé
Auteurs :	J. Haubrock, Auteur ; W. Wermink, Auteur ; G. F. Versteeg, Auteur
Année de publication :	2009
Article en page(s) :	p. 9862–9870
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Carbonate
Résumé :	The kinetics of the reaction of dimethyl carbonate (DMC) and phenol to methyl phenyl carbonate (MPC) and the subsequent disproportion and transesterification reaction of methyl phenyl carbonate (MPC) to diphenyl carbonate (DPC) have been studied. Experiments were carried out in a closed batch reactor in the temperature range from 160 to 200 °C for initial reactant ratios of DMC/phenol from 0.25 to 3 and varying catalyst (titanium-(n-butoxide)) concentrations. The concept of a closed, ideally stirred, isothermal batch reactor incorporating an activity based reaction rate model has been used to fit kinetic parameters to the experimental data taking into account the catalyst concentration, the initial reactant ratio DMC/phenol and the temperature.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie071176d

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9854–9861

Titre :	Reaction from dimethyl carbonate to diphenyl carbonate. 1 : experimental determination of the chemical equilibria
Type de document :	texte imprimé
Auteurs :	J. Haubrock, Auteur ; M. Raspe, Auteur ; G. F. Versteeg, Auteur
Année de publication :	2009
Article en page(s) :	p. 9854–9861
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Carbonate diphényle Carbonate
Résumé :	New experimental equilibrium data of the reaction of dimethyl carbonate (DMC) and phenol to methyl phenyl carbonate (MPC) and the subsequent disproportion and transesterification reaction of MPC to diphenyl carbonate (DPC) are presented and interpreted in terms of the reaction equilibrium coefficients. Experiments have been carried out in the temperature range between 160 and 200 °C and for initial reactant ratios of DMC/phenol from 0.25 to 3. By employing activities instead of “only” mole fractions in the calculation of the reaction equilibrium coefficients, the influence on the reactant ratio DMC/phenol on the derived equilibrium values for the reaction of DMC to MPC could be reduced, especially for temperatures of 160 °C. The activity based equilibrium coefficient for the transesterification reaction from MPC with phenol to DPC and methanol is constant within experimental uncertainty and, therefore, largely independent of the initial reactant ratio DMC/phenol at temperatures of 160 and 180 °C. The temperature dependence of the equilibrium coefficients Ka,1 and Ka,2 has been fitted by applying the well-known Van’t Hoff equation, resulting in the expressions ln Ka,1 = −2702/T[K] + 0.175 and ln Ka,2 = −2331/T[K] − 2.59. It has been demonstrated that these equations have fair, in the case of ln Ka,1, and excellent, in the case of ln Ka,2, predictive capabilities, even for experimental conditions that deviate significantly from those used in this study. Hence, it is expected that the derived temperature dependent correlations for Ka,1 and Ka,2 based on activities can be used in reactive distillation models to assess different process configurations in the manufacture of DPC starting from DMC and phenol.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie0711170

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9848–9853

Titre :	Electrochemical oxidation of lignosulfonate : total organic oarbon oxidation kinetics
Type de document :	texte imprimé
Auteurs :	A. Dominguez-Ramos, Auteur ; R. Aldaco, Auteur ; Angel Irabien, Auteur
Année de publication :	2009
Article en page(s) :	p. 9848–9853
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Electrochemical
Résumé :	Lignin derivatives account for a significant fraction of biorefractory pollutants in wastewater from the pulp and paper industry. Electrochemical oxidation has been described as an efficient alternative in wastewater treatment based on electrogenerated oxidation. Lignosulfonate was selected in this work as a biorefractory reference pollutant. Total organic carbon (TOC) removal was higher than 80% under the selected experimental conditions, where chemical oxygen demand (COD) was in the range 500−1500 mg O2 L−1, current density was between 30 and 60 mA cm−2, and the concentrations of sodium sulfate and sodium chloride supporting electrolytes were 2500 and 5000 mg L−1. Experimental conditions were selected to evaluate the technical suitability of the process and to establish a kinetic model and parameters. Experiments were carried out in a laboratory scale single cell flow electrochemical reactor with boron-doped diamond electrodes. A first-order kinetic model is in good agreement with previously reported results, and kinetic parameters depending mainly on the current density agree well with previous references. A model describing the influence of the current density in the kinetic parameters allows us to calculate the surface electrochemical reaction kinetic constant and the mass transfer coefficient.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie801109c

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9842–9847

Titre :	Production of hydrogen by dehydrogenation of cyclohexane in high-pressure (1−8 atm) membrane reactors using amorphous silica membranes with controlled pore sizes
Type de document :	texte imprimé
Année de publication :	2009
Article en page(s) :	p. 9842–9847
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Hydrogen--Production
Résumé :	We have developed membrane reactors to dehydrogenate cyclohexane, using amorphous silica membranes with controlled pore sizes, and successfully operated them under pressures ranging from 1 to 8 atm. The membranes were prepared by chemical vapor deposition (CVD) using tetramethoxysilane (TMOS) or dimethoxydiphenylsilane (DMDPS). Both membranes had hydrogen-permselective properties. At 473−573 K, the TMOS-derived membranes showed hydrogen permeances on the order of 10−8 mol m−2 s−1 Pa−1, whereas the DMDPS-derived membranes showed permeances on the order of 10−6 mol m−2 s−1 Pa−1. Both membrane reactors produced hydrogen with conversions greater than equilibrium, and the DMDPS-derived membrane achieved higher conversion than the TMOS-derived membrane because of the greater hydrogen extraction effect of the DMDPS-derived membrane. In addition, it should be noted that this is the first report of successful operation of membrane reactors with highly hydrogen-permselective silica membranes under pressure.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800786h

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9834–9841

Titre :	Dissolution of mineral fiber in a formic acid solution : kinetics, modeling, and gelation of the resulting sol
Type de document :	texte imprimé
Auteurs :	Henrik Grenman, Auteur ; Fernando Ramirez, Auteur ; Kari Eranen, Auteur
Année de publication :	2009
Article en page(s) :	p. 9834–9841
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Mineral fiber
Résumé :	A new inorganic adhesive based on sol−gel technology has been developed recently. The sol is produced by dissolving a mineral material, with silica as the major compound, in formic acid. In this work, the kinetics and mechanisms of the solid−liquid reaction of the amorphous mineral raw material with formic acid were studied. The effect of different variables, such as temperature, acid concentration, and fiber load, were examined. Moreover, the influence of various parameters on the gelation rate of the resulting sol was investigated at different temperatures. The dissolution of the mineral fiber was found to be strongly dependent on the temperature and fiber load, but moderately dependent on the acid concentration as the pH of the solution was buffered by the formic acid. The kinetic model developed for the dissolution process accurately describes the experimental results and can thus be used for design and optimization of the process. The gelation studies showed that the temperature and the amount dissolved are the variables most affecting the gelation time. The knowledge of the gelation kinetics is important when striving for a high dry solid content in the sol, while still avoiding premature gelation in production, transport, and storage.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800267a

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9812–9833

Titre :	Crystal shape engineering
Type de document :	texte imprimé
Auteurs :	Michael A. Lovette, Auteur ; Andrea Robben Browning, Auteur ; Derek W. Griffin, Auteur
Année de publication :	2009
Article en page(s) :	p. 9812–9833
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Industrial crystallization
Résumé :	In an industrial crystallization process, crystal shape strongly influences end-product quality and functionality, as well as downstream processing. In addition, nucleation events, solvent effects, and polymorph selection play critical roles in both the design and operation of a crystallization plant and the patentability of the product and process. Therefore, investigation of these issues, with respect to a priori prediction, is (and will continue to be) an important avenue of research. In this review, we discuss the state-of-the-art in modeling crystallization processes over a range of length scales relevant to nucleation through process design. We also identify opportunities for continued research and specific areas where significant advancements are needed.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800900f

[article]
in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 9795–9811

Titre :	Radical desorption kinetics in emulsion polymerization.1 : Theory and simulation
Type de document :	texte imprimé
Auteurs :	Hugo F. Hernande, Auteur ; Klaus Tauer, Auteur
Année de publication :	2009
Article en page(s) :	p. 9795–9811
Note générale :	Industrial chemistry
Langues :	Anglais (eng)
Mots-clés :	Polymer molecule
Résumé :	Radical desorption is one of the most important physical processes influencing the kinetics of free-radical emulsion polymerization. Desorption of any molecule from a polymer particle can only take place if the molecule reaches the particle surface during its random diffusion through the polymer phase. For doing this the molecule must survive all possible competitive reactions taking place simultaneously inside the particle. Once at the surface it must also overcome a certain energy barrier in order to leave the particle. This energy barrier is determined mainly by the difference in the chemical potential of the molecule between the particle and the continuous phase (including interfacial tension effects) and by additional barriers such as the presence of a stabilizer layer. In this molecular picture of the desorption process all molecules inside the polymer particle can desorb from the particle at a rate determined by its energy barrier and diffusion coefficient. It is for this reason that desorption of the smaller and more hydrophilic molecules is predominant. In this paper we propose the use of Brownian dynamics (BD) algorithms for simulating the desorption of radicals from polymer particles and estimate the corresponding desorption rate coefficients. The results obtained in simple systems are found to be in very good agreement with the rate coefficients of desorption determined theoretically. For more complex systems, such as core−shell particles, nonspherical particles, hollow particles, or particles with a gradient in monomer concentration, BD simulations open the possibility to obtain easy, reliable estimations of the desorption rate coefficients, which are difficult to obtain using the experimental or theoretical methods currently available. This article is also intended to be a comprehensive and critical review of the different available theories of radical desorption in emulsion polymerization.
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie800304t

Industrial & engineering chemistry research / Paul, Donald R. . Vol. 47 n°24

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