Showing papers in "Industrial & Engineering Chemistry Research in 2001"
TL;DR: In this paper, a modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid, which is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers.
Abstract: A modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid. With conventional one-fluid mixing rules, the equation of state is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers. The three pure-component parameters required for nonassociating molecules were identified for 78 substances by correlating vapor pressures and liquid volumes. The equation of state gives good fits to these properties and agrees well with caloric properties. When applied to vapor−liquid equilibria of mixtures, the equation of state shows substantial predictive capabilities and good precision for correlating mixtures. Comparisons to the SAFT version of Huang and Radosz reveal a clear improvement of the proposed model. A brief comparison with the Peng−Robinson model is also given for vapor−liquid equilibria of binary systems, confirming the good performance of the suggested equation of state. ...
2,739 citations
TL;DR: Sonochemical engineering is a field involving the application of sonic and ultrasonic waves to chemical processing as discussed by the authors, which offers the potential for shorter reaction cycles, cheaper reagents, and less extreme physical conditions, leading to less expensive and perhaps smaller plants.
Abstract: Sonochemical engineering is a field involving the application of sonic and ultrasonic waves to chemical processing. Sonochemistry enhances or promotes chemical reactions and mass transfer. It offers the potential for shorter reaction cycles, cheaper reagents, and less extreme physical conditions, leading to less expensive and perhaps smaller plants. The amount of things that can be accomplished with sonochemistry is, at this stage, only limited by the minds of those working in this exciting field. Existing literature on sonochemical reacting systems is chemistry-intensive, and applications of this novel means of reaction in environmental remediation and pollution prevention seem almost unlimited. For example, environmental sonochemistry is a rapidly growing area that deals with the destruction of organics in aqueous solutions. However, some theoretical and engineering aspects are not fully understood. This paper reviews the field comprehensively by combining the existing knowledge from chemistry with insi...
891 citations
TL;DR: In contrast to the chemical theory, in which nonideality is explained in terms of chemical reactions between the species, SAFT and similar approaches relate non-ideality to the intermolecular forces involved as discussed by the authors.
Abstract: We present a review of recent advances in the statistical associating fluid theory (SAFT). In contrast to the “chemical theory”, in which nonideality is explained in terms of chemical reactions between the species, SAFT and similar approaches relate nonideality to the intermolecular forces involved. Such physical theories can be tested against molecular simulations, and improvements to the theory can be made where needed. We describe the original SAFT approach and more recent modifications to it. Emphasis is placed on pointing out that SAFT is a general method and not a unique equation of state. Applications to a wide variety of fluids and mixtures are reviewed, including aqueous mixtures and electrolytes, liquid−liquid immiscible systems, amphiphilic systems, liquid crystals, polymers, petroleum fluids, and high-pressure phase equilibria.
625 citations
TL;DR: In this article, the feasibility of using supercritical carbon dioxide, another environmentally benign solvent, for the separation of organic solutes from an ionic liquid was investigated, and the results showed that supercritical fluid extraction is a viable separation technique with the additional benefits of environmental sustainability and pure product recovery.
Abstract: Ionic liquids (ILs) hold great potential as replacements for traditional volatile organic solvents and have been shown to be a viable medium for numerous types of reactions. This work investigates the feasibility of using supercritical carbon dioxide, another environmentally benign solvent, for the separation of organic solutes from an ionic liquid. Recovery rates of aromatic and aliphatic solutes from 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) are given. Supercritical fluid extraction is shown to be a viable separation technique with the additional benefits of environmental sustainability and pure product recovery.
521 citations
TL;DR: In this paper, the authors consider the design of multi-product, multi-echelon supply chain networks, where the objective is to minimize the total annualized cost of the network, taking into account both infrastructure and operating costs.
Abstract: We consider the design of multiproduct, multi-echelon supply chain networks. The networks comprise a number of manufacturing sites at fixed locations, a number of warehouses and distribution centers of unknown locations (to be selected from a set of potential locations), and finally a number of customer zones at fixed locations. The system is modeled mathematically as a mixed-integer linear programming optimization problem. The decisions to be determined include the number, location, and capacity of warehouses and distribution centers to be set up, the transportation links that need to be established in the network, and the flows and production rates of materials. The objective is the minimization of the total annualized cost of the network, taking into account both infrastructure and operating costs. A case study illustrates the applicability of such an integrated approach for production and distribution systems with or without product demand uncertainty.
493 citations
TL;DR: A critical review of the developments in these areas with particular emphasis on adsorption characteristics, progress in controlling the pore sizes, and a comparison of pore size distributions using traditional and newer models is provided in this article.
Abstract: The discovery of periodic mesoporous MCM-41 and related molecular sieves has attracted significant attention from a fundamental as well as applied perspective. They possess well-defined cylindrical/hexagonal mesopores with a simple geometry, tailored pore size, and reproducible surface properties. Hence, there is an ever-growing scientific interest in the challenges posed by their processing and characterization and by the refinement of various sorption models. Further, MCM-41-based materials are currently under intense investigation with respect to their utility as adsorbents, catalysts, supports, ion-exchangers, and molecular hosts. In this article, we provide a critical review of the developments in these areas with particular emphasis on adsorption characteristics, progress in controlling the pore sizes, and a comparison of pore size distributions using traditional and newer models. The model proposed by the authors for adsorption isotherms and criticalities in capillary condensation and hysteresis is found to explain unusual adsorption behavior in these materials while providing a convenient characterization tool.
485 citations
TL;DR: A reconstruction-based fault identification approach using a combined index for multidimensional fault reconstruction and identification and a new method to extract fault directions from historical fault data is proposed.
Abstract: Process monitoring and fault diagnosis are crucial for efficient and optimal operation of a chemical plant. This paper proposes a reconstruction-based fault identification approach using a combined index for multidimensional fault reconstruction and identification. Fault detection is conducted using a new index that combines the squared prediction error (SPE) and T2. Necessary and sufficient conditions for fault detectability are derived. The combined index is used to reconstruct the fault along a given fault direction. Faults are identified by assuming that each fault in a candidate fault set is the true fault and comparing the reconstructed indices with the control limits. Fault reconstructability and identifiability on the basis of the combined index are discussed. A new method to extract fault directions from historical fault data is proposed. The dimension of the fault is determined on the basis of the fault detection indices after fault reconstruction. Several simulation examples and one practical c...
456 citations
TL;DR: In this paper, a packed-bed microchemical system consisting of a microfluidic distribution manifold, a microchannel array, and a 25-μm microfilter for immobilizing solid particulate material within the reactor chip and carrying out different heterogeneous chemistries is presented.
Abstract: A microchemical device has been built in silicon and glass by using microfabrication methods including deep-reactive-ion etch technology, photolithography, and multiple wafer bonding. The microchemical system consists of a microfluidic distribution manifold, a microchannel array, and a 25-μm microfilter for immobilizing solid particulate material within the reactor chip and carrying out different heterogeneous chemistries. Multiple reagent streams (specifically, gas and liquid streams) are mixed on-chip, and the fluid streams are brought into contact by a series of interleaved, high-aspect-ratio inlet channels. These inlet channels deliver the reactants continuously and cocurrently to 10 reactor chambers containing standard catalytic particles. The performance of the microfabricated “packed-bed” reactor is compared to that of traditional multiphase packed-bed reactors in terms of fluid flow regimes, pressure drop, and mass transfer. The hydrogenation of cyclohexene is used as a model reaction to measure t...
445 citations
TL;DR: The low-temperature behavior of the selective catalytic reduction (SCR) process with feed gases containing both NO and NO2 was investigated in this article, where the two main reactions are 4NH3 + 2NO + 2 NO2 → 4N2 + 6H2O and 2NH3+ 2NO2 → NH4NO3 + N2 + H2O.
Abstract: The low-temperature behavior of the selective catalytic reduction (SCR) process with feed gases containing both NO and NO2 was investigated. The two main reactions are 4NH3 + 2NO + 2NO2 → 4N2 + 6H2O and 2NH3 + 2NO2 → NH4NO3 + N2 + H2O. The “fast SCR reaction” exhibits a reaction rate at least 10 times higher than that of the well-known standard SCR reaction with pure NO and dominates at temperatures above 200 °C. At lower temperatures, the “ammonium nitrate route” becomes increasingly important. Under extreme conditions, e.g., a powder catalyst at T ≈ 140 °C, the ammonium nitrate route may be responsible for the whole NOx conversion observed. This reaction leads to the formation of ammonium nitrate within the pores of the catalyst and a temporary deactivation. For a typical monolithic sample, the lower threshold temperature at which no degradation of catalyst activity with time is observed is around 180 °C. The ammonium nitrate route is interesting from a standpoint of general DeNOx mechanisms: This reac...
393 citations
TL;DR: In this article, the methods of synthesizing silicon-based materials from rice husks and their applications are reviewed in a very comprehensive manner, including silicon carbide, silica, silicon nitride, silicon tetrachloride, and pure silicon.
Abstract: Rice husk (RH) has now become a source for a number of silicon compounds, including silicon carbide, silica, silicon nitride, silicon tetrachloride, zeolite, and pure silicon. The applications of such materials derived from rice husks are very comprehensive. The methods of synthesizing these silicon-based materials from RHs and their applications are reviewed in this paper.
368 citations
TL;DR: In this paper, a one-time-only hydrothermal synthesis with a short reaction time of 3 h at 373 K using a gel with the composition Al2O3:SiO2:Na2O:H2O = 1.2:2:120 (in moles) and porous α-alumina support tubes seeded with zeolite NaA crystals.
Abstract: Zeolite NaA membranes were prepared reproducibly by a one-time-only hydrothermal synthesis with a short reaction time of 3 h at 373 K using a gel with the composition Al2O3:SiO2:Na2O:H2O = 1:2:2:120 (in moles) and porous α-alumina support tubes seeded with zeolite NaA crystals. A dense intergrown zeolite crystal layer of about 30 μm in thickness was formed on the outer surface. The zeolite NaA membranes were highly permeable to water vapor but impermeable to every gas unless dried completely. The completely dried membranes displayed gas permeation behavior attributed to Knudsen diffusion, indicating the presence of interstitial spaces between the zeolite crystal particles, or nonzeolitic pores. The membranes displayed excellent water-permselective performance in pervaporation (PV) and vapor permeation (VP) toward water/organic liquid mixtures. With an increase in temperature, both the permeation flux Q and the separation factor α increased, and the membrane performance was much better for VP than for PV. ...
TL;DR: In this paper, the effect of water in the casting solution on the geometrical properties of the polyvinylidene fluoride (PVDF) flat-sheet membranes was discussed and evaluated.
Abstract: Polyvinylidene fluoride (PVDF) flat-sheet membranes were prepared for membrane distillation (MD). Pure water was used as a pore-forming additive in the casting solution. Dimethylacetamide (DMAC) was used as the solvent. The polymer solutions were cast over a glass plate or over a nonwoven polyester backing material. The prepared supported and unsupported PVDF membranes were characterized in terms of their nonwettability, pore size and porosity. MD experiments were carried out using a vacuum membrane distillation (VMD) configuration and employing pure water or chloroform/water binary mixtures as the feed. The influence of some relevant parameters, such as the feed temperature, stirring rate, or downstream pressure on the MD flux was studied. The effect of water in the casting solution on the geometrical properties of the membrane is discussed and evaluated. The dependence of the MD flux and separation factor on the geometrical properties of the supported and unsupported membranes was also studied.
TL;DR: In this paper, a one-step global reaction with E = 141.2 ± 15.8 kJ/mol and ln A = 22.2 − 2.9 s-1 was proposed to capture the main features of the beech wood powder degradation process.
Abstract: Weight loss curves of thin layers (150 μm) of beech wood powder, measured for heating rates of 1000 K/min and final temperatures in the range 573−708 K, show final char yields of 37−11%. The process is kinetically controlled and, for the most part, isothermal. A one-step global reaction, with E = 141.2 ± 15.8 kJ/mol and ln A = 22.2 ± 2.9 s-1, is a degradation mechanism capable of capturing the main features of the process. The thermogravimetric curves also allow the formation rate constants to be estimated for char and total volatiles (activation energies of 111.7 ± 14.3 and 148.6 ± 17.4 kJ/mol, respectively) and, once integrated byproduct distribution, those for liquids and gases (activation energies of 148 ± 17.2 and 152.7 ± 18.2 kJ/mol, respectively). A comparison is provided with pyrolysis mechanisms available in the literature.
TL;DR: In this paper, the adsorption capacities of carbon dioxide on six commercial hydrotalcite-like compounds and the main factors (aluminum content, anion type, water content, and heat treatment temperature) influencing their adaption capacity at high temperatures have been investigated using a gravimetric technique.
Abstract: The adsorption capacities of carbon dioxide on six commercial hydrotalcite-like compounds and the main factors (aluminum content, anion type, water content, and heat treatment temperature) influencing their adsorption capacity at high temperatures have been investigated using a gravimetric technique. There is an optimum aluminum content and heat treatment temperature for the adsorption capacity. The carbonate anion favors adsorption of carbon dioxide compared to OH-, and a low content of water also improves the adsorption capacity. The carbon dioxide adsorption capacity is mainly dependent on the microporous volume, interlayer spacing, and layer charge density of the hydrotalcite-like compounds.
TL;DR: In this paper, the maximum uptake of lithium from seawater by the adsorbent was 40 mg/g, which is the maximum value among the adorbents studied to date.
Abstract: Manganese oxide adsorbent (H1.6Mn1.6O4) was synthesized from precursor Li1.6Mn1.6O4 that was obtained by heating LiMnO2 at 400 °C. LiMnO2 was prepared by two methods: hydrothermal and reflux. The crystallite size of Li1.6Mn1.6O4 and its delithiated product was slightly higher by the hydrothermal method as compared to the reflux method. The adsorbents prepared by the two methods were compared in terms of physical characteristics and lithium adsorption from seawater. The maximum uptake of lithium from seawater by the adsorbent was 40 mg/g, which is the maximum value among the adsorbents studied to date.
TL;DR: In this paper, the authors examined the sorptionenhanced production of H2 via the steam−methane reforming process using a mixture of Ni-based commercial reforming catalyst and Ca-based sorbent obtained from commercial dolomite.
Abstract: This study examined the sorption-enhanced production of H2 via the steam−methane reforming process using a mixture of Ni-based commercial reforming catalyst and Ca-based sorbent obtained from commercial dolomite. The rates of the reforming, water−gas shift, and CO2 removal reactions are sufficiently fast that combined reaction equilibrium was closely approached, allowing for >95 mol % H2 (dry basis) to be produced in a single step. A dolomite pretreatment procedure was developed to remove sulfur, which was necessary to avoid poisoning of the reforming catalyst. The multicycle durability of the catalyst−sorbent mixture was studied as a function of regeneration temperature and gas composition using a laboratory-scale fixed-bed reactor. Twenty-five-cycle tests showed only moderate activity loss under most of the regeneration conditions studied. The primary loss in activity was associated with the inexpensive sorbent instead of the more expensive catalyst.
TL;DR: In this paper, the authors present a summary review of the extent to which membrane processes have been integrated into industrial practice, and predictions about future developments and the possible impact of new membrane science and technologies.
Abstract: Membrane science and technology has led to significant innovation in both processes and products over the last few decades, offering interesting opportunities in the design, rationalization, and optimization of innovative productions. The most interesting developments for industrial membrane technologies are related to the possibility of integrating various of these membrane operations in the same industrial cycle, with overall important benefits in product quality, plant compactness, environmental impact, and energetic aspects. Possibilities for membrane engineering might also be of importance in new areas. The case of transportation technologies is of particular interest. The purpose here is to present a summary review of the extent to which membrane processes have been integrated into industrial practice. Some of the most interesting results already achieved in membrane engineering will be presented, and predictions about future developments and the possible impact of new membrane science and technolog...
TL;DR: In this article, an overview of surface diffusion and capillary condensate flow in porous media is provided, with emphasis placed on the distinction between purely surface diffusion, multilayer surface diffusion.
Abstract: This review provides an overview of surface diffusion and capillary condensate flow in porous media. Emphasis has been placed on the distinction between purely surface diffusion, multilayer surface diffusion, and capillary condensate flow.
TL;DR: In this paper, a microwave-induced pyrolysis process was evaluated by studying the degradation of high-density polyethylene and aluminum/polymer laminates in a semibatch bench-scale apparatus.
Abstract: The performance of a novel microwave-induced pyrolysis process was evaluated by studying the degradation of high-density polyethylene and aluminum/polymer laminates in a semibatch bench-scale apparatus. The results showed that the new process has the same general features as other, more traditional, pyrolytic processes but with the advantage that it is able to deal with problematic wastes such as laminates. Degradation experiments were performed between 500 and 700 °C and the relationship between temperature, residence time of the pyrolytic products in the reactor, and the chemical composition of the hydrocarbon fraction produced was investigated. Toothpaste tubing was used as an example of a laminated material to be treated with the novel process. Clean aluminum was recovered together with hydrocarbons and the trial proved that the process has excellent potential for the treatment of plastic wastes on a commercial scale.
TL;DR: In this paper, the authors examined the gasification of cellulose, xylan, and lignin mixtures in supercritical water at 623 K and 25 MPa.
Abstract: We examined the gasification of cellulose, xylan, and lignin mixtures in supercritical water at 623 K and 25 MPa. Our results indicate that the lignin content significantly affects the amount and composition of the product gas. Thus, we surmised that cellulose or xylan is likely to function as a hydrogen donor to lignin. A set of equations developed to estimate the amount and composition of the product gas accurately predicted the actual results using only the lignin fraction as a parameter. This confirmed the importance of the lignin fraction effect on supercritical water gasification characteristics.
TL;DR: In this article, α-Al2O3 support disks have been used for the separation of xylene isomers vapors in the temperature range 22−275 °C and feed partial pressures up to ∼ 0.7−0.9 kPa.
Abstract: Oriented MFI membranes made by secondary growth on the surface of α-Al2O3 support disks have been evaluated for the separation of xylene isomers vapors in the temperature range 22−275 °C and feed partial pressures up to ∼0.7−0.9 kPa. It is found that the separation performance of these membranes is directly related to the synthesis conditions and the resulting membrane microstructure. Thick (12−18 μm) and c-oriented membranes (type A membranes) made by 24-h growth at 175 °C exhibit single-component p-xylene/o-xylene permselectivity as high as 150 at 100 °C but very modest separation factors (usually <5) are obtained with binary feed mixtures, a result of a drastic increase in the flux of o-xylene in the presence of p-xylene. Thin (2−3 μm) and (h0h)-oriented membranes (type B membranes) made by 120-h growth at 90 °C exhibit comparable single-component and binary permeation behavior but suffer from lower selectivities/separation factors (up to 12) as a result of cracks formed after calcination for template ...
TL;DR: In this article, the authors present a tool that is becoming more realistic for use in the description of the detailed flow fields within fixed beds of low tube-to-particle diameter ratio (N).
Abstract: Computational fluid dynamics (CFD) is a tool that is becoming more realistic for use in the description of the detailed flow fields within fixed beds of low tube-to-particle diameter ratio (N). The...
TL;DR: In this paper, a fixed-bed micro-reactor with a K-promoted Fe catalyst was used for CO2 hydrogenation at 1 MPa and with modified residence times in the range of 0.042−21.4 g·s/cm3.
Abstract: CO2 hydrogenation on a K-promoted Fe catalyst was studied in a fixed-bed microreactor between 300 and 400 °C, at 1 MPa, and with modified residence times in the range of 0.042−21.4 g·s/cm3. For temperatures below 360 °C, organic products almost identical with those found in the traditional Fischer−Tropsch reaction with H2/CO were found (paraffins and α-olefins). At 400 °C, formation of carbon deposited on the catalyst became a major reaction. Concerning the mechanism of hydrocarbon formation, the effect of residence time resulted in catalyst particle selectivity values for hydrocarbons always higher than zero. This indicates that, besides the two-step reaction mechanism via CO, a direct hydrocarbon formation from CO2 can occur in principle. With a reaction scheme proposed from these experimental results, a kinetic model was developed using integration and regression features of ASPEN PLUS. Calculated values for CO2 conversion and CO and total hydrocarbon selectivities agree with the experimental data with...
TL;DR: In this article, the dissolution of cellulose and the structure, transparency, and mechanical properties of regenerated cellulose (RC) films were investigated by 13C NMR, ultraviolet, and infrared spectroscopies; scanning electron microscopy; X-ray diffraction; and a strength test.
Abstract: Regenerated cellulose (RC) films having various viscosity-average molecular weights (Mη) ranging from 2.2 × 104 to 8.2 × 104 g/mol were prepared from cotton linters in 6 wt % NaOH/4 wt % urea aqueous solution by coagulation with 2 M acetic acid and 2% H2SO4 aqueous solution. The dissolution of cellulose and the structure, transparency, and mechanical properties of the RC films were investigated by 13C NMR, ultraviolet, and infrared spectroscopies; scanning electron microscopy; X-ray diffraction; and a strength test. The RC films exhibited the cellulose II crystalline form and a homogeneous structure with 85% light transmittance at 800 nm. 13C NMR spectroscopy indicated that the presence of urea in NaOH aqueous solution significantly enhanced the intermolecular hydrogen bonding between cellulose and the solvent, resulting in a higher solubility of cellulose and the complete transition of its crystalline form from I to II. The tensile strength (σb) of the RC films in the dry state increased with increasing ...
TL;DR: In this article, the ability of cross-flow ultrafiltration combined with photocatalytic reactions, to separate TiO2 particles from treated water in drinking water treatment was investigated with and without UV irradiation.
Abstract: This study investigated the ability of cross-flow ultrafiltration (UF), combined with photocatalytic reactions, to separate TiO2 photocatalysts from treated water in photocatalytic drinking water treatment. The effect of natural organic matter (i.e., humic acids) and cross-flow velocities on UF fluxes and organic removal was explored with and without UV irradiation in the photocatalytic reactor. The interaction between the two solutes in the system, humic acids and TiO2 photocatalysts, played a significant role in the formation of dense cake layers at the membrane surface, leading to a greater flux decline during ultrafiltration of TiO2 particles. According to visual observations of the used membranes and the estimation of back-transport velocities of the solutes, a substantial amount of TiO2 deposited on the membrane induces more humic acids to accumulate at the membrane through the adsorption of humic acids onto TiO2 particles. The humic-acid-laden TiO2 particles offered more than four times higher spec...
TL;DR: In this paper, an optimization-based approach to selecting both a product development and introduction strategy and a capacity planning and investment strategy for pharmaceutical companies is presented. And the overall problem is formulated as a mixed-integer linear programming (MILP) model, taking account of both the particular features of pharmaceutical active ingredient manufacturing and the global trading structures.
Abstract: Pharmaceutical companies are undergoing major changes to cope with the new challenges of the modern economy. The globalization of the business, the diversity and complexity of new drugs, the increasing tightness of capital, and the diminishing protection provided by patents are some of the factors driving these changes. All stages of the business value chain are affected: from the development of new drugs to the management of the manufacturing and marketing networks. This paper describes an optimization-based approach to selecting both a product development and introduction strategy and a capacity planning and investment strategy. The overall problem is formulated as a mixed-integer linear programming (MILP) model. This takes account of both the particular features of pharmaceutical active ingredient manufacturing and the global trading structures. An illustrative example is presented to demonstrate the applicability of the proposed model.
TL;DR: In this paper, the synthesis of 3-alkoxymethyl-1-methylimidazolium, tetrafluoroborate and hexafluorophosphate is reported.
Abstract: The synthesis of 3-alkoxymethyl-1-methylimidazolium, 3-alkoxymethyl-1-hexylimidazolium, and 3-alkoxymethyl-1-butoxymethylimidazolium tetrafluoroborate and hexafluorophosphate are reported. Fifty-eight salts were synthesized, and 38 of them are new ionic liquids. Trends in the properties of these liquid compounds are discussed. The prepared salts were examined according to their antielectrostatic effect; the surface resistance, half decay time, and maximum voltage induced on polyethylene film were measured. Thus, this work shows that ionic liquids have antielectrostatic properties and that their densities are linearly dependent on the length and kind of substituents in the 1 and 3 positions on the imidazole ring.
TL;DR: In this article, the reactivity of pretreated corn fiber with respect to enzymatic hydrolysis was evaluated using a simultaneous saccharification and fermentation (SSF) system consisting of β-glucosidase-supplemented Trichoderma reesei cellulase together with fermentation by Saccharomyces cerevisiae.
Abstract: Dried, milled corn fiber (0.2−0.5 kg) was fractionated by treatment with either hot liquid water (3−4 kg) at low solids loadings (5−10%) or steam (0.1−0.4 kg) at high solids loadings (>50%) at 210−220 °C for 2 min, using the same novel process equipment. Pentosan recovery and inhibition of yeast fermentation were evaluated and compared. In addition, the reactivity of pretreated fiber with respect to enzymatic hydrolysis was evaluated using a simultaneous saccharification and fermentation (SSF) system consisting of β-glucosidase-supplemented Trichoderma reesei cellulase together with fermentation by Saccharomyces cerevisiae. Greater solubilization was achieved at 215 °C with hot liquid water at 5% solids loading than with steam at 70% solids loading (54% solubilization vs 37%). The lignocellulosic residue from this hot liquid water fractionation was enriched in glucan. Conversely, the steam fractionation caused no significant change in the fraction of glucan in the residue, relative to the feed material. I...
TL;DR: Jog et al. as mentioned in this paper showed how to accurately predict the properties of chain-like molecules with single or multiple dipolar sites (Jog, P. K., Chapman, W. M., Gang, J.; Donohue, M. D., and Gubbins, K. E.).
Abstract: Phase behavior is strongly affected by dipolar interactions in a wide range of systems including those containing ketones, aldehydes, ethers, and esters. Multiple polar sites are present in various polar copolymers as well as in polyethers and polyesters. Although theories have been developed for nearly spherical polar molecules and for nonpolar chain molecules, accounting simultaneously for a single multipolar interaction and molecular shape has remained an unsolved problem of statistical-mechanics-based perturbation theory (Gray, C. G.; Gubbins, K. E. Theory of Molecular Fluids I; Clarendon Press: Oxford, U.K., 1984. Walsh, J. M.; Gang, J.; Donohue, M. D. Fluid Phase Equilib. 1991, 65, 209). Accurate accounting for the effect of multiple polar sites in nonspherical molecules has been well beyond expectation. In recent work, we solved part of this problem by showing how to accurately predict the properties of chainlike molecules with single or multiple dipolar sites (Jog, P. K.; Chapman, W. G. Mol. Phys...
TL;DR: In this paper, a modified shrinking-core model for the chemical reaction control was proposed, in which the effective surface area is proportional to the degree of hydrolyzed PET, x, affected by formation and growth of pore and crack on PET powder.
Abstract: Poly(ethylene terephthalate) (PET) powder from waste bottles was degradated at atmospheric pressure in 3−9 M sulfuric acid below 150−190 °C for 12 h to clarify the mechanism for a feedstock recycle process. Terephthalic acid (TPA) and ethylene glycol (EG) were produced by the acid-catalyzed heterogeneous hydrolysis of PET in sulfuric acid. The TPA yield agreed with the degree of hydrolysis of PET, but the EG yield decreased with increasing sulfuric acid concentration because of carbonization of EG. The kinetics of hydrolysis of PET in sulfuric acid could be explained by a modified shrinking-core model for the chemical reaction control, in which the effective surface area is proportional to the degree of hydrolyzed PET, x, affected by formation and growth of pore and crack on PET powder. The apparent rate constant was proportional to the reciprocal of the particle size and the activity of sulfuric acid, and the activation energy was 88.7 kJ/mol.