| 1. |
- Salminen, Eero, et al.
(författare)
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Kinetics upon Isomerization of α,β-Pinene Oxides over Supported Ionic Liquid Catalysts Containing Lewis Acids
- 2014
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Ingår i: Journal of Industrial and Engineering Chemistry. - : American Chemical Society (ACS). - 1226-086X .- 1876-794X .- 0888-5885 .- 1520-5045. ; 53:52, s. 20107-20115
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Tidskriftsartikel (refereegranskat)abstract
- Wood extractives such as α-pinene oxide and β-pinene oxide are important renewable chemicals for the synthesis of fine chemicals, pharmaceuticals, and value-added intermediates. In this work, catalytic transformations of biomass derived extractives, isomerization of α,β-pinene oxides were studied over supported ionic liquid catalysts (SILCAs). SILCAs consist of catalytic species (e.g., metal nanoparticles or metal complexes) in a thin layer of ionic liquid which is immobilized on a solid support material (e.g., active carbon cloth). The reaction kinetics of the isomerization reactions over supported ionic liquid catalysts were studied and modeled. Mechanistic kinetic models describing the differences in selectivity and activity of the catalysts containing different ionic liquids were developed, and the models described the reaction rates and product distributions very well.
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| 2. |
- Andersson, Kerstin I., et al.
(författare)
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Removal of Lignin from Wastewater Generated by Mechanical Pulping Using Activated Charcoal and Fly Ash : Adsorption Kinetics
- 2011
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 50:13, s. 7733-7739
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Tidskriftsartikel (refereegranskat)abstract
- The possible application of adsorption for the removal of lignin-related material found in wastewater generated by mechanical pulping was investigated. Activated charcoal and fly ash were used as adsorbents in batch experiments. The lignin-related material exhibited properties well-suited for adsorption onto both adsorbents, although the sorption capacity of activated charcoal exceeds that of fly ash. The experimental data were fitted to pseudo-first- and pseudo-second-order rate kinetic expressions, and an attempt was made to find the rate-limiting step involved in the adsorption processes. The results showed that lignin adsorption onto both activated charcoal and fly ash follows pseudo-second-order rate kinetics and that both boundary-layer diffusion and intraparticle diffusion are likely involved in the rate-limiting mechanisms. Adsorption is an interesting option in advanced wastewater treatment, and fly ash appears to be a suitable low-cost adsorbent for recalcitrant organic pollutants.
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| 3. |
- Andersson, Kerstin I, et al.
(författare)
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Removal of Lignin from Wastewater Generated by Mechanical Pulping Using Activated Charcoal and Fly Ash: Adsorption Isotherms and Thermodynamics
- 2011
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 50:13, s. 7722-7732
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Tidskriftsartikel (refereegranskat)abstract
- Lignin-related material found in wastewater from thermomechanical pulping resists conventional biological treatment, entailing the use of advanced removal methods. In this work, the use of adsorption for removing lignin-related material was investigated. Activated charcoal and fly ash were used to study the adsorption behavior of lignin and to determine the adsorption capacities of these two adsorbents. Experimental data were fitted to various isotherm equations to find the best description of the sorption systems, and the corresponding thermodynamic parameters were calculated. Fly ash exhibited good sorption properties, although its sorption capacity was inferior to that of activated charcoal. Both the Freundlich and Langmuir equations provided reasonable models of the sorption processes, and the thermodynamic parameters indicated that sorption onto activated charcoal is endothermic, whereas sorption onto fly ash appears to be exothermic. Fly ash is a low-cost material that is often available on-site and offers an interesting alternative to high-cost advanced wastewater treatment systems for removing recalcitrant organic materials.
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| 4. |
- Andersson, Niklas, et al.
(författare)
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Model-Based Comparison of Batch and Continuous Preparative Chromatography in the Separation of Rare Earth Elements
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:42, s. 16485-16493
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Tidskriftsartikel (refereegranskat)abstract
- The demand for rare earth elements (REEs) is growing, while the future supply is uncertain. Their unique electronic characteristics make them irreplaceable, and the commercial value of pure fractions is high. A model-based simulation study is presented that compares batch chromatography with the twin-column MCSGP (multicolumn countercurrent solvent gradient purification) process for ion-exchange chromatography of the four-component system neodymium, samarium, europium, and gadolinium. The last three components are considered products with individual purity requirements of 99%. The twin-column process has been shown to be a good alternative to the batch process regarding modifier consumption and productivity since it enables internal recycling to achieve high purities. A new cut strategy for MCSGP is applied where subfractions are taken from each outlet. Two multiobjective optimizations with yield, solvent productivity, and productivity objectives show that the MCSGP process is a better alternative than batch chromatography.
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| 5. |
- Arjmand, Mehdi, 1986, et al.
(författare)
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Evaluation of CuAl2O4 as an Oxygen Carrier in Chemical-Looping Combustion
- 2012
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:43, s. 13924-13934
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Tidskriftsartikel (refereegranskat)abstract
- The chemical-looping combustion (CLC) process is a novel solution for efficient combustion with intrinsic separation of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor where the fuel, or gasification products of the fuel, reacts with the solid oxygen carrier. In this work, copper(II) aluminate (CuAl2O4) was assessed as a potential oxygen carrier using methane as fuel. The carrier particles were produced by freeze–granulation and calcined at 1050 °C for a duration of 6 h. The chemical-looping characteristics were evaluated in a laboratory-scale fluidized-bed reactor in the temperature range of 900–950 °C during 45 alternating redox cycles. The oxygen carrier exhibited reproducible and stable reactivity behavior in this temperature range. Neither agglomeration nor defluidization was noticed in any of the cycles carried out at 900–925 °C. However, after reactivity tests at 950 °C, soft agglomeration and particle fragmentation were observed. Systematic phase analysis of the Cu–Al–O system during the redox cycle was carried out as a function of duration of reduction and oxygen concentration during the oxidation period. It was found that the CuAl2O4 is reduced to copper(I) aluminate (CuAlO2; delafossite), Cu2O, and elemental Cu. The CuAlO2 phase is characterized by slow kinetics for oxidation into CuO and CuAl2O4. Despite this kinetic limitation, complete conversion of methane with reproducible reactivity of the oxygen carrier is achieved. Thus, CuAl2O4 could be a potential oxygen carrier for chemical-looping combustion.
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| 6. |
- Arjmand, Mehdi, 1986, et al.
(författare)
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Sulfur Tolerance and Rate of Oxygen Release of Combined Mn-Si Oxygen Carriers in Chemical-Looping with Oxygen Uncoupling (CLOU)
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:50, s. 19488-19497
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur tolerance and rate of oxygen release of combined Mn-Si oxygen carriers for chemical-looping with oxygen uncoupling (CLOU) is investigated. The oxygen carriers were produced by spray-drying and calcined at 1150 degrees C. The resistance toward sulfur and the rates of oxygen release were evaluated in a laboratory-scale fluidized-bed reactor. It was found that the combined Mn-Si oxygen carrier is tolerant to SO2, at least up to a partial pressure of 5000 vppm. The rates of oxygen release were determined in the temperature range of 975 to 1100 degrees C using devolatilized wood char as fuel while fluidizing with N-2, to maintain a low oxygen partial pressure surrounding the particles. The Arrhenius parameters k(o) and E-app for the release of oxygen were estimated for the investigated materials assuming a zero-order reaction with respect to oxygen. The rates of oxygen release were relatively high, particularly at above 1050 degrees C. From the obtained reaction rates, the solids inventory required for combustion of coal was determined to be as low as 40 kg/MWth in the fuel reactor at 1100 degrees C. The results indicated that combined Mn-Si oxygen carriers could be interesting materials for the CLOU process by virtue of their resistance to sulfur deactivation and high rate of oxygen release.
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| 7. |
- Aulin, Christian, et al.
(författare)
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Multilayered Alkyd Resin/Nanocellulose Coatings for Use in Renewable Packaging Solutions with a High Level of Moisture Resistance
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:7, s. 2582-2589
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Tidskriftsartikel (refereegranskat)abstract
- A surprisingly simple and rapid methodology for large-area, lightweight, and thin laminate coatings with remarkable moisture barrier properties is introduced. Commercially available paperboards are coated with thin layers of nanocellulose. The nanocellulose coating induces a surface smoothening effect on the coated sheets as characterized by environmental scanning electron microscopy and white light interferometry. A moisture-protective layer of renewable alkyd resins is deposited on the nanocellulose precoated sheets using a water-borne dispersion coating process or lithographic printing. Through an auto-oxidation process, the applied alkyd resins are transformed into moisture sealant layers. The moisture barrier properties are characterized in detail by water vapor permeability measurements at different levels of relative humidity. The water vapor barrier properties of the nanocellulose precoated substrates were significantly improved by thin layers of renewable alkyd resins. The effect of the alkyd resin properties, coating technologies, and base paper substrates on the final barrier performance of the sheets were studied. It was found that the nanocellulose coating had a notable effect on the homogeneity and barrier performance of the alkyd resin layers and in particular those alkyd resin layers that were applied by printing. The concept is environmentally friendly, energy-efficient, and economic and is ready for scaling-up via continuous roll-to-roll processes. Large-scale renewable coatings applicable for sustainable packaging solutions are foreseen.
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| 8. |
- Auvray, Xavier, 1986, et al.
(författare)
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Sulfur Dioxide Exposure: A Way To Improve the Oxidation Catalyst Performance
- 2013
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:41, s. 14556-14566
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of nitric oxide and propylene was studied over a model alumina-supported platinum catalyst. Two treatments (22 h at 250 degrees C and 2 h at 800 degrees C) involving sulfur dioxide were performed in order to understand the effect of SO2 aging. The role and stability of sulfur species stored during aging were investigated by the reduction of sulfated samples at 500 degrees C and temperature-programmed reduction (TPR) up to 800 degrees C. The low activity obtained after aging without reduction revealed the poisoning effect of surface sulfur species. The reduction at 500 degrees C released half of the surface species, which increased the catalytic activity for both NO and C3H6 oxidation. The TPR removed the most stable sulfur species and improved the activity during cooling. The catalyst aged in SO2 at high temperature showed the greatest activity for both reactions because of SO2 exposure and low sulfur storage.
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| 9. |
- Azimi, Golnar, 1985, et al.
(författare)
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Mn–Fe Oxides with Support of MgAl2O4, CeO2, ZrO2 and Y2O3–ZrO2 for Chemical-Looping Combustion and Chemical-Looping with Oxygen Uncoupling
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:25, s. 10358-10365
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of utilizing a combined oxide (Mn0.75Fe0.25)(2)O-3 as an oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) has been investigated. To increase the strength and attrition resistance of such particles, the oxygen carrier was prepared together with MgAl2O4, CeO2, ZrO2 and Y2O3-ZrO2 as supports. The oxygen-carrier particles were prepared using spray-drying. Each material was calcined for 4 h at 950, 1100 or 1200 degrees C. The materials were studied in a batch fluidized bed reactor to investigate their oxygen release and uptake potential and also their reactivity with CH4 and syngas. To gauge the mechanical stability of the different materials, the attrition resistance was measured in a jet-cup apparatus. With the exception of the material with MgAl2O4, the oxygen uncoupling property of the active combined oxides was largely kept intact using the added support materials. On the basis of the results from the reactivity tests and the measured attrition rates for all the particles, the material utilizing ZrO2 support seems to be the most promising candidate as an oxygen carrier for gaseous and solid fuels. However, due to phase transformations of the ZrO2 at higher temperatures, the calcination and operational temperature should likely not exceed 950 degrees C.
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| 10. |
- Bakhtiary-Davijany, Hamidreza, et al.
(författare)
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Analysis of External and Internal Mass Transfer at Low Reynolds Numbers in a Multiple-Slit Packed Bed Microstructured Reactor for Synthesis of Methanol from Syngas
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:42, s. 13574-13579
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of mass transfer limitations in an integrated micro packed bed reactor-heat exchanger (IMPBRHE) for methanol synthesis was experimentally investigated. Experiments were performed with three different particle size distributions (50-200 mu m) of a Cu-based catalyst at 80 bar and 215-270 degrees C. Negligible effects of pore diffusion limitations on the performance of the reactor under methanol synthesis conditions for catalyst particle diameters up to 125 mu m were found. Due to a very low Reynolds numbers (similar to 1) and dominance of molecular diffusion, variation of the total pressure was applied as a suitable technique to alter the diffusivities of reactants in the gas mixture by dilution, while keeping the reactant flow and partial pressure constant. No significant change in the CO conversion was observed in the temperature range 235-255 degrees C, pressure range 50-90 bar, and for reactant contact times of 105-308 ms.g/mL. The same procedure was applied to a laboratory. fixed bed reactor with similar results. Possible heat transfer effects associated with the dilution were shown to be negligible. We therefore conclude that both reactor systems operate in the absence of external mass transfer limitations.
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| 11. |
- Berguerand, Nicolas, 1978, et al.
(författare)
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Use of Nickel Oxide as a Catalyst for Tar Elimination in a Chemical-Looping Reforming Reactor Operated with Biomass Producer Gas
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:51, s. 16610-16616
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Tidskriftsartikel (refereegranskat)abstract
- A secondary tar-cleaning process based on Chemical-Looping Reforming (CLR) was investigated for upgrading biomass producer gas, derived from the Chalmers University of Technology 2-4 MW indirect gasifier. The experiments were conducted in a bench-scale CLR reactor using a manufactured nickel oxide (NiO) catalyst. Although Ni is a well-documented and efficient steam-reforming catalyst, it is susceptible to rapid deactivation under tar-rich conditions. The aim of this study was to explore the advantages of CLR as a gas-cleaning application, a process which offers continuous regeneration of the carbon deposits on catalysts. The tar-reforming performance of this Ni material and its influence on the gas composition and in particular its potential to increase the H2/CO ratio, were studied. The system was tested at reforming temperatures that ranged from 700°C to 880°C and at oxygen concentrations of 1.0% and 2.2% in the inlet feed to regenerator section. The results confirm the strong ability of the catalyst to reform tars. Higher process temperatures clearly promoted tar conversion, with 96% overall conversion at 880°C (99% if benzene is excluded), as compared with 45% conversion at 700°C. The hydrogen production was favored when temperature was raised. Though, a maximum ratio H2/CO of 2.2 was observed at 750°C. Finally, no time-on-stream deactivation of the catalyst in the CLR was observed during the test, which lasted almost 7 hours.
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| 12. |
- Bäbler, Matthäus U., et al.
(författare)
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Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Semicontinuous Operation Mode
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:45, s. 14814-14823
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Tidskriftsartikel (refereegranskat)abstract
- Solid supported evaporation (SSE) is a simple, nonselective method for isolating nonvolatile compounds from a solution. The solution is put in contact with porous polymer beads onto which the compound deposits upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety, thermal decomposition, and solid handling, as the loaded beads form a free flowing granular material that is easily recovered. In this paper, SSE in a semicontinuous operating mode is investigated where the solution is continuously fed to (respectively sprayed over) an agitated bed of dry beads put under vacuum. It is found that under conditions where the solvent evaporation fate is high with respect to the feed rate, high bead loadings can be achieved before extensive sticking of beads and compound to the vessel walls occurs. The type of compound and solvent had little influence on the process performance, and, in cases where this was explored, the bead loading was found to be homogeneous. Based on a balance equation for the solvent fed to the system, a model is developed that results in a simple scale up criterion. The latter was successfully applied for transferring SSE from lab to the kilo lab scale.
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| 13. |
- Carabante, Ivan, et al.
(författare)
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Reutilization of porous sintered hematite bodies as effective adsorbents for arsenic(V) removal from water
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:32, s. 12689-12696
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Tidskriftsartikel (refereegranskat)abstract
- A method was developed to enhance the arsenic adsorption capacity of porous bodies of sintered hematite. The method comprised the formation of a coating of 1 wt % iron oxide nanoparticles on the raw material. The nanoparticles showed two distinct habits: spherical habit, likely ferrihydrite, and acicular habit, likely goethite and/or akaganéite. The specific surface area of the hematite raw material increased from 0.5 to 3.75 m2/g, and the adsorption capacity increased from negligible to 0.65 mg of [As]/g as calculated from equilibrium and breakthrough adsorption data. Equilibrium adsorption data of arsenate on the adsorbent from a solution at pH 5 followed the Langmuir model, while breakthrough adsorption data for a 500 μg/L arsenate solution at pH 5 followed the Thomas model. The adsorbed arsenic could be desorbed using distilled water at pH 12. These results show the potential for the reutilization of waste products comprising coarse hematite bodies as adsorbents.
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| 14. |
- Creaser, Derek, 1966, et al.
(författare)
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Kinetic modeling of autothermal reforming of dimethyl ether
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 49:20, s. 9712-9719
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Tidskriftsartikel (refereegranskat)abstract
- A global kinetic model was developed for the autothermal reforming of dimethyl ether (DME) over a Pd-Zn/Al2O3 catalyst on a cordierite monolith. A kinetic model consisting of five key overall reactions was found to capture the main features of experimental data. The modeling also accounted for heat transport effects in the reactor that are of importance when coupling the exothermic oxidation reactions with endothermic steam reforming reactions. The modeling confirmed that oxidation reactions dominate near the inlet of the reactor, generating a local hot spot. The heat from oxidation reactions accelerates the reforming reactions. Water adsorption was found to have a weak detrimental influence on the activity. Based on the model, the influence of the reactor scale and oxygen supply by air feed on the performance of the reactor was examined.
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| 15. |
- Dahlström, Christina, 1977-, et al.
(författare)
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Microstructure Variations in Paper Coating : Direct Observations
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:24, s. 8246-8252
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Tidskriftsartikel (refereegranskat)abstract
- Non-uniformities in the coating layer, such as porosity variations and binder distributions, are known to affect print uniformity and barrier properties. However, in the literature the results are rather scarce or sometimes conflicting.We acquired high quality images of coated paper cross sections using field emission scanning electron microscopy in combination with a new argon-ion-beam milling technique to directly observe and analyse the coating microstructures in relation to underlying base sheet structures.The results showed that coating porosity varied with mass density of the underlying base sheet for the relatively bulky clay/GCC coating, whereas for the more compact clay coating, the effect was small. Areas with more fibres in the base sheet were more compressed by calendering, resulting in a decreased coating porosity. A unique binder enriched layer of less than 500 nm thickness was found at the coating surface as well as at the coating/base sheet interface.
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| 16. |
- Danwittayakul, Supamas, et al.
(författare)
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Enhancement of photocatalytic degradation of methyl orange by supported zinc oxide nanorods/zinc stannate (ZnO/ZTO) on porous substrates
- 2013
-
Ingår i: Industrial and Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:38, s. 13629-13636
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Tidskriftsartikel (refereegranskat)abstract
- Dye wastewater from textile industries is reported to be a major river pollutant. Zinc stannate (ZTO) was grown directly on zinc oxide (ZnO) nanorod-coated polyester fiber membranes and porous ceramic substrates by a mild hydrothermal method, where the nanorods supplied zinc ions for ZTO growth. Photocatalytic degradation of a methyl orange aqueous solution under UV-light irradiation was monitored for up to 3 h duration. The higher photocatalytic activity of ZnO/ZTO catalysts on ceramic substrates was attributed to the large surface area of the nanocomposites. 50% methyl orange and similar to 95% methyl orange could be degraded within 1 and 3 h of UV-light irradiation, respectively, by using the porous-ceramic-supported catalysts (C-ZnO/10ZTO), because of efficient charge separation. Moreover, the formation of ZTO islands on ZnO nanorods led to an enhancement in the photocatalytic activity in the exposed areas of electron-rich ZnO nanorods.
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| 17. |
- de Araujo, Antonio C. B., et al.
(författare)
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Systematic Approach to the Design of Operation and Control Policies in Activated Sludge Systems
- 2011
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 50:14, s. 8542-8557
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the systematic design of a control structure for a biological wastewater treatment process as given by the test-bed Benchmark Simulation Model No. 1 (BSM1) and Activated Sludge Model No. 1 (ASM1). The objective of this work was to formalize and implement a systematic and yet simple procedure for the selection of control structures in wastewater treatment plants (WWTPs) and to show that the application of the proposed methodology agrees with the "empirical" findings regarding the operation of this process. The motivation underlying this endeavor was to search for a control configuration that leads to optimal economic operation while promptly rejecting disturbances at lower layers in the control hierarchy, thus avoiding violation of the more important regulatory constraints on effluent discharge. We started by optimizing a steady-state nonlinear model of the process for various important disturbances. The results confirmed that it is economically optimal to control the oxygen concentration in the aerobic basins and the nitrate in the second anoxic tank at their respective lower bounds, whereas the effluent ammonia from the bioreactors should be controlled at its upper limit. In addition, because it is good practice to operate with minimal manipulation, the wastage flow rate should be fixed at its nominal optimal set point. The proposed decentralized control configuration, consisting of simple PI controllers, is capable of maintaining the process well within the regulatory limits at a small cost when dynamic disturbances represented by three weather files affect the process, therefore suggesting that, according to the applied systematic methodology, more complex (multivariable) regulators are not necessary for the ASM1 process.
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| 18. |
- de Araujo Filho, Cesar Augusto, et al.
(författare)
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Kinetic model for homogeneously catalyzed halogenation of glycerol
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:4, s. 1523-1530
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Tidskriftsartikel (refereegranskat)abstract
- A new kinetic model for the halogenation of polyalcohols, e.g. chlorination of glycerol with gaseous HCl in the presence of homogeneous acid catalysts was developed. The model is based on a reaction mechanism, which includes esterification and epoxidation steps followed by halogenation steps. The principle of quasi-steady state was applied to the ester and ionic intermediates appearing in the model and rate equations were derived. Furthermore, some simplified cases of the rate equations were considered, such as immediate water removal from the reaction mixture and analytical solutions for the simplified kinetic models were derived. The model was verified against experimental data obtained from laboratory-scale semibatch reactors. The conclusion is that the model worked very well, predicting correctly the glycerol conversion and the product distribution of α-, β-, α,β- and α,γ-chlorinated products. The kinetic model can be used for design of reactors for homogeneously catalyzed halogenation.
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| 19. |
- Dinculescu, Daniel Dumitru, et al.
(författare)
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Experimental Study of Local Axial Mixing in a Pilot-Scale Cold Burner
- 2011
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 50:2, s. 1070-1078
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Konferensbidrag (refereegranskat)abstract
- The residence time distribution (RTD) approach was used to characterize the flow and mixing behavior of burners. This analysis consists of injecting an inert gaseous tracer into the feed and measuring its change in concentration at various detection points. The responses are then used to characterize the flow behavior and, thus, the local mixing in the space delimited by the injection and probe points. The outcome of this RTD analysis is a flow model that, combined with an appropriate kinetics, constitutes an efficient tool in examining the ways to reduce NOx emissions in existing installations. A replica made in plastic at a 1:1 scale of an industrial gas burner was used for cold experiments. As preliminary information, a chart of local mixing in the axial section of the burner chamber was obtained. Even though far from working conditions, cold experiments are beneficial because they reveal the existence of possible major flow disturbances, leading to imperfect or incomplete combustion, a source of NOx.
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| 20. |
- Duan, Ran, 1987-, et al.
(författare)
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Acid-Catalyzed Synthesis of Foamed Materials from Renewable Sources
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:45, s. 17597-17603
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Tidskriftsartikel (refereegranskat)abstract
- In this study, lightweight biobased foamed materials were successfully synthesized by the modification of renewable polysaccharides, such as starch and microcrystalline cellulose. Low-cost and nontoxic organic acids were utilized as catalysts in the first-step esterification reaction of the synthesis. The effects of different reaction conditions on the water absorbency and weight loss of freeze-casted polysaccharide–citrate–chitosan foams are discussed. Physical properties, such as pore-size distributions and compressive stress–strain curves, of the foams were determined. The characterization results show that the amide bonds formed between the carboxylic acid groups of polysaccharide–citrate and the amino groups of chitosan are crucial to the foamed material’s performance.
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| 21. |
- Eta, Valerie, et al.
(författare)
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Synthesis of dimethyl carbonate from methanol and carbon dioxide : Circumventing thermodynamic limitations
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society. - 0888-5885 .- 1520-5045. ; 49:20, s. 9609-17
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of dimethyl carbonate from methanol and CO2 catalyzed by ZrO2 doped with KCl was investigated using chemical traps for water to circumvent thermodynamic limitations. The reaction, promoted by magnesium, occurred via the formation of carbonated magnesium methoxide (CMM) which adsorbed on the surface of ZrO2. The surface migration of the oxygen atom of ZrO2 to the surface methoxy groups of CMM resulted in the formation of dimethyl carbonate. The resulting MgO then reacted with methanol forming water and regenerating magnesium methoxide. The water formed reacted with the dehydrating agent, thus shifting the equilibrium toward a higher yield of DMC. The yield of 7.2 mol % DMC and 13.6 mol % conversion of methanol was obtained when methanol reacted with CO2 at 150 °C and 9.5 MPa for 8 h. The plausible reaction pathway is described.
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| 22. |
- Farzaneh, Meisam, 1982, et al.
(författare)
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A Study of Fuel Particle Movement in Fluidized Beds
- 2013
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:16, s. 5791-5805
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Tidskriftsartikel (refereegranskat)abstract
- Lagrangian simulations are performed to investigate the process of fuel mixing in fluidized-bed energy converters. The computations are carried out for a narrow (0.4 m) and a wide (1.2 m) bed. Movement of a limited number of large and light particles in a bulk of heavy and small particles is studied using a multigrid technique proposed by Farzaneh et al. Preferential positions and the dispersion coefficient of the fuel particles are obtained under different operating conditions. In addition, detailed information on the motion of the fuel particles in the form of upward and downward velocity is obtained. Furthermore, in an attempt to investigate the effect of the inlet boundary conditions on the process of fuel mixing, two boundary conditions are employed: a uniform velocity profile at the air distributor and a non-uniform velocity profile obtained by including the air supply system in the computational domain.It is observed that the numerical simulations which include the air supply system in the computational domain, improve the prediction of the hydrodynamic behavior of the bed. However, regarding the averaged movement pattern of the fuel particles, the effect of the boundary condition employed is not significant in the 0.4 m bed. As for the wide 1.2 m bed, the simulation results differ substantially from the experiments when the uniform velocity profile is employed as inlet boundary condition. Including the plenum in the simulations considerably improves the results, but they are still not in a perfect agreement with the experiments.
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| 23. |
- Fleig, Daniel, 1980, et al.
(författare)
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Influence of Operating Conditions on SO3 Formation during Air and Oxy-Fuel Combustion
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:28, s. 9483−9491-9491
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Tidskriftsartikel (refereegranskat)abstract
- Because SO3 participates in both high- and low-temperature corrosion processes, there is a general concern about the SO3 formation under oxy-fuel fired conditions. This work has the aim to evaluate the influence of combustion parameters on the formation of SO3. Experiments were conducted in oxy-fuel and air-fired experiments with propane as fuel and injection of SO2 in the oxidizer. The SO3 concentration was measured with a controlled condensation method at the furnace outlet as well as in the flame. The experiments show that the gas-phase is an important contributor to SO3 formation and that the SO3 formation is strong during burnout of the fuel. In oxy-fuel combustion with wet flue-gas recycle (FGR), more SO3 was formed than during dry FGR at similar temperature conditions, which indicates that H2O enhances SO3 formation. The experiments also show that the SO3 formation rises with an increase in furnace temperature. Because temperature and residence time in the furnace increases with reduced FGR ratio, the FGR ratio directly influences the SO3 formation in oxy-fuel combustion. This was obvious during the experiments, and the SO3 concentration rose with a reduced FGR ratio.
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| 24. |
- Fleig, Daniel, 1980, et al.
(författare)
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SO3 Formation under Oxyfuel Combustion Conditions
- 2011
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 50:14, s. 8505-8514
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Tidskriftsartikel (refereegranskat)abstract
- The sulfur chemistry in oxyfuel combustion systems has received growing attention lately. The formation of SO(3) is of special concern, because of the elevated SO(2) concentrations found in oxyfuel, compared to air-fuel conditions. The present study focuses on the gas-phase chemistry and examines the impact of different combustion parameters and atmospheres on the formation of SO(3) in oxyfuel and air-fuel flames, using a detailed gas-phase model. The work also includes a summary of the presently available SO(x) data from experiments in laboratory and pilot-scale combustors. The reviewed experimental data, as well as the modeling results, show significantly increased SO(3) concentrations in oxyfuel, compared to air-fuel conditions. The modeling results reveal a complex behavior of the SO(3) formation, which is influenced by direct and indirect effects of the SO(2), O(2), NO(x), and CO content in the flue gas. One of the main contributors to the increased SO(3) concentration in oxyfuel, compared to air-fuel conditions, is the high concentration of SO(2) in oxyfuel combustion. The modeling also shows that the stoichiometry, residence time, and flue-gas cooling rate are critical to the SO(3) formation. Thus, in addition to the stoichiometry of the flame, the flue-gas recycling conditions are likely to influence the formation of SO(3) in oxyfuel combustion.
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| 25. |
- Ghorbanzadeh, Mehdi, et al.
(författare)
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Modeling the cellular uptake of magnetofluorescent nanoparticles in pancreatic cancer cells : a quantitative structure activity relationship study
- 2012
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:32, s. 10712-10718
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Tidskriftsartikel (refereegranskat)abstract
- An artificial neural network was employed to predict the cellular uptake of 109 magnetofluorescent nanoparticles (NPs) in pancreatic cancer cells on the basis of quantitative structure activity relationship method. Six descriptors chosen by combining self organizing map and stepwise multiple linear regression (MLR) techniques were used to correlate the nanostructure of the studied particles with their bioactivity using MLR and multilayered perceptron neural network (MLP-NN) modeling techniques. For the MLR and MLP-NN models, the correlation coefficient was 0.769 and 0.934, and the root-mean-square error was 0.364 and 0.150, respectively. The results obtained after a leave-many-out cross-validation test revealed the credibility of MLP-NN for the prediction of cellular uptake of NPs. In addition, sensitivity analysis of MLP-NN model indicated that the number of hydrogen-bond donor sites in the organic coating of a NP is the predominant factor responsible for cellular uptake.
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| 26. |
- Gourdon, Mathias, 1980, et al.
(författare)
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Crystallization in a Pilot Evaporator: Aqueous Solutions of Na2CO3 and Na2SO4
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 49:5, s. 2401-2409
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Tidskriftsartikel (refereegranskat)abstract
- Sodium carbonate and sodium sulfate cause problems by forming scales in black liquor evaporators, reducing heat transfer and cleaning intervals. An experimental investigation of the crystallization behavior during evaporation of different aqueous solutions of sodium carbonate and sodium sulfate has been carried out. The analysis is based oil changes in heat transfer coefficients and crystal masses. The results from this work show large variation in the distribution of the crystal mass, depending on the composition of the solution. Solutions with the crystalline form of either dicarbonate or sodium carbonate exhibit high propensity to form scales on the heat transfer surface. Solutions with the crystalline form of burkeite, however, do not show the same attraction to the heat transfer surface; they are more likely to crystallize in the circulating solution. Thus, the heat transfer is not as affected as for dicarbonate or sodium carbonate.
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| 27. |
- Grénman, Henrik, et al.
(författare)
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Modeling the influence of wood anisotropy and internal diffusion on delignification kinetics
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society. - 0888-5885 .- 1520-5045. ; 49:20, s. 9703-11
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Tidskriftsartikel (refereegranskat)abstract
- A general mathematical model for the chemical pulping of wood including coupled chemical reactions and diffusion limitations in anisotropic wood chips was developed. The model, which consists of coupled parabolic partial differential equations (PDEs) and ordinary differential equations (ODEs), describes the time-dependent behavior of wood chips as they are exposed to chemicals in the liquid phase. In addition to the reaction−diffusion phenomena, the model describes the change of the wood chip porosity during the process. A numerical algorithm that combines spatial discretization by finite differences with a stiff ODE solver based on the backward difference method was used as an efficient strategy to solve the mass balances of wood chips in batch reactors. Numerical simulations with the software can be used to predict the progress of industrial delignification, that is, production of primarily cellulose through chemical pulping. The effect of the reaction parameters, such as the temperature and the concentrations of the alkaline delignification chemicals, as well as the sizes of the wood chips, can be evaluated with the model, the final goal being the intensification of the chemical pulping process. The model can be used to describe both the current kraft pulping (sulfate pulping) technique, as well as other processes, such as sulfite pulping and pulping in nonaqueous solvents.
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| 28. |
- Hallac, B. B., et al.
(författare)
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Effect of Ethanol Organosolv Pretreatment on Enzymatic Hydrolysis of Buddleja davidii Stem Biomass
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 49:4, s. 1467-1472
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Tidskriftsartikel (refereegranskat)abstract
- Ethanol organosolv pretreatment was performed on Buddleja davidii to evaluate this bioresource as a potential feedstock for bioethanol production. B. davidii was pretreated and delignified, while 85% of the glucose content of the untreated material was retained in the pretreated solid fraction. The enzymatic hydrolysis showed that organosolv pretreatment produced solid substrates that were readily digestible by cellulases. Gel-permeation chromatography was used to determine the degree of polymerization (DP) of cellulose, and solid-state cross polarization/magic angle spinning 13C NMR experiments were conducted to study the changes in crystallinity and ultrastructure of cellulose. The results showed a decrease in DP along with an increase in the relative proportions of para-crystalline and amorphous cellulose and a decrease in cellulose Ia̧ and Ib̃. Removal of lignin and hemicellulose, reduction in DP, and decrease in the crystalline allomorphs (Ia̧ and Ib̃) increased the amenability of the biomass to enzymatic degradation.
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| 29. |
- Halvarsson, Sören, et al.
(författare)
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Manufacture of High-Performance Rice-Straw Fiberboards
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 49:3, s. 1428-1435
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Tidskriftsartikel (refereegranskat)abstract
- Rice straw, a waste agriculture material grown and harvested in Willows, CA, was used,is a raw material in the production of thin medium- and high-density fiberboards (MDFs and HDFs). The rice straw was cleaned, size-reduced, and soaked in water before being refined. Defibration was performed in it pressurized pilot-plant single-disk refiner, OHP 20". The fiber production capacity reached a level of 63 kg/h. and the proper fiber quality for MDF/HDF production was established. Analysis of the produced fiber showed an average fiber length of approximately 0.9 mm, in average fiber width of 31 mu m, a shive weight of below 24%, and a dust content of less than 30%. Production of fiberboards was performed by addition of 3%, 4%, and 5% methylene diphenyl diisocyanate (MDI). The flexural properties, internal bond strength, and thickness swelling of the produced fiberboards were evaluated according to ASTM methods. The finished fiberboards based on rice straw and MDI resin showed excellent properties. The internal bond (IB) reached levels of 2.6 MPa, and the modulus of rupture (MOR) and modulus of elasticity (MOE) showed levels comparable to those of wood-based fiberboards and were acceptable according to the requirements or medium-density fiberboard (MDF) for interior applications (American National Standards Institute, ANSI A208.2-2002). The water-repelling properties of the 3-min rice-straw fiberboards were encouraging; the thickness swelling, (TS) was in the range of 15-30%. Two different methods to avoid adhesion between the press plates and the resinated fiber material during hot pressing were investigated: protective paper sheets were placed between the fiber mat and press plates, or a press-release agent was sprayed oil steel plates that were then placed ill the press before pressing Satisfactory results were obtained with both methods, and no adhesion was observed between the fiberboard and the steel plates. The method of using press-release agent during pressing had no notable negative effects oil the fiberboard properties.
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| 30. |
- Hanning, Malin, 1987, et al.
(författare)
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CaMn0.9Mg0.1O3-δ as Oxygen Carrier in a Gas-Fired 10 kWth Chemical-Looping Combustion Unit
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:21, s. 6923-6932
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Tidskriftsartikel (refereegranskat)abstract
- Spray dried particles of the perovskite material CaMn0.9Mg0.1O3-δ have been examined as oxygen carrier for chemical-looping combustion of natural gas. The experiments have been conducted in a continuously operating reactor with the nominal size 10 kWth. The oxygen carrier particles showed excellent ability to convert fuel and complete combustion was reached at certain conditions. In general, the CO2 yield increased with increased fuel reactor temperature and with increased circulation rate. The oxygen carrier was able to release gaseous oxygen through the so called CLOU-mechanism (Chemical-Looping with Oxygen Uncoupling). When the fuel reactor was fluidized by inert gas, there was oxygen release at temperatures above 700°C, reaching a maximum of more than 3% for temperatures above 850°C. Gas phase oxygen was also measured during operation with fuel, as long as the fuel conversion was complete. When the fuel reactor temperature was above 900°C and a high enough circulation rate was maintained, complete combustion of the fuel was achieved with an oxygen concentration in the outlet stream from the fuel reactor of more than 1%. This suggests that a substantial part of the fuel is converted by gaseous oxygen released from the particles. The oxygen carrier particles were subject to more than 350 h of fluidization, of which more than 175 h was at high temperature and more than 55 h with addition of fuel. The particles did not show any tendencies to form hard agglomerations or break down to fines due to attrition during the experiments. Operational problems included high rate of particle elutriation, which was likely an effect of a mismatch between the size and density of the particles, the air flow and the cyclone.
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| 31. |
- Hao, Wenming, 1984-, et al.
(författare)
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Activated carbons for water treatment prepared by phosphoric acid activation of hydrothermally treated beer waste
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:40, s. 15389-15397
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Tidskriftsartikel (refereegranskat)abstract
- Activated carbons were produced by chemical activation of hydrothermally carbonized (HTC) beer waste, withphosphoric acid as the activation agent. The activation was optimized within a full factorial design, using the outcome of 19different experiments. Four different parameters (concentration of the acid, activation time, activation temperature, flow rate)were analyzed with respect to their influence on the median pore size. The concentration of H3PO4 had a strong positive effecton the median pore size. The specific surface areas of these activated carbons were ∼1000 m2/g, which compared wellcommercially available activated carbons. The activated carbons had mostly large pores with a size of ∼4 nm, and a significantamount of acid surface groups. Scanning electron microscopy (SEM) revealed that the morphology of the HTC beer wastechanged significantly after the chemical activation. The capacity to adsorb methylene blue from aqueous solutions was 341 mg/g,for one of the activated carbons at pH 7. A Langmuir model described the uptake of the dye quite well, which suggested ahomogeneous adsorption of Methylene Blue (MB).
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| 32. |
- He, Hanbing, et al.
(författare)
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Morphology-controlled synthesis of sodium hexa-titanate nanowhiskers by changing evaporation rate of NaCl-KCl molten salts
- 2013
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:43, s. 15034-15040
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Tidskriftsartikel (refereegranskat)abstract
- Na2Ti6O13 nanowhiskers with controllable morphologies were prepared via a simple molten salt evaporation method using a small quantity of NaCl-KCl as molten salt. The synthesized products were characterized by X-ray diffraction, field emission scanning electron microscope, and transmission electron microscope. The optimal growth dynamic conditions for synthesis of Na2Ti6O13 nanowhiskers were also studied and discussed. According to thermogravimetry-differential scanning calorimetry analysis, the calcination process was designed to include two stages, lower temperature for reaction and higher temperature for evaporation of molten salt. Nanowhiskers and nanorods with different diameters can be obtained under different evaporation conditions. By comparing residual amounts of NaCl-KCl on product surfaces calculated by determined kinetic equation and experimental results only using NaCl as molten salt, it was revealed that the molten salt evaporation rates could play an important role on the morphologies of Na2Ti6O13. A formation mechanism was provided based on nucleation and growth model and an oriented aggregation process to understand different morphologies of Na2Ti 6O13. This simple molten salt evaporation method would be suitable for large scale synthesis
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| 33. |
- Hedayati, Ali, 1984, et al.
(författare)
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Evaluation of Novel Ceria-Supported Metal Oxides As Oxygen Carriers for Chemical-Looping Combustion
- 2012
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:39, s. 12796-12806
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen carrier particles consisting of 60 wt % copper, iron, or manganese oxide supported on 40 wt % ceria (CeO2) or gadolinia doped-ceria (Ce0.9Gd0.1O1.9) have been manufactured and examined as oxygen carrier materials for chemical-looping combustion (CLC). Unlike conventional support materials, such as alumina (Al2O3), these ceria-based support materials are active under prevailing conditions in the fuel reactor and have the ability to participate in redox reactions. The oxygen carrier materials were synthesized via extrusion and were examined by successive oxidation and reduction cycles in a bench-scale fluidized bed reactor made of quartz. The experiments were conducted at 900 and 925 degrees C for copper-based materials, and at 950 degrees C for iron- and manganese-based materials. Methane or syngas (50% CO and 50% H-2) using a flow rate of 900 mL/min for Cu-based materials and 450 mL/min for Mn- and Fe-based materials was used as the fuel. For all experiments, 15 g of oxygen carrier was used. The oxidation was performed with a gas mixture of 5% O-2 and 95% N-2. The results show that CeO2 and Ce0.9Gd0.1O1.9 are viable support materials for the oxides of copper and iron. Moreover, the active particles supported on Ce0.9Gd0.1O1.9 were more reactive compared to those supported on CeO2. CH4 was completely converted to CO2 and H2O by CuO supported on Ce0.9Gd0.1O1.9, while the conversion of CH4 for Fe2O3 supported on Ce0.9Gd0.1O1.9 was as high as 90%. Ceria-supported Mn3O4 particles showed poor performance when CH4 was used as fuel. Syngas was fully converted to CO2 and H2O by all the oxygen carriers synthesized and examined in this work. The ability of CuO and Mn2O3 to release O-2 in gas phase when fluidized in inert background was also investigated; in the case of copper oxide, substantial oxygen release was observed. Analysis of fresh and used particles by X-ray diffractometry did not reveal the formation of any unexpected phases. All particles showed good fluidization properties with low attrition and little tendency toward agglomeration.
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| 34. |
- Hjärtstam, Stefan, 1978, et al.
(författare)
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Oxy-Fuel Combustion Modeling: Performance of Global Reaction Mechanisms
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:31, s. 10327-10337
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Tidskriftsartikel (refereegranskat)abstract
- Three global reaction mechanisms derived for oxy-fuel combustion and one global reference mechanism are investigated and compared under gaseous oxy-fuel combustion conditions. The aim is to evaluate their prediction of major in-flame species and temperature by comparison with a detailed reaction mechanism (validated for oxy-fuel conditions) and experimental data. The evaluation is performed using a 1D plug flow reactor (PFR) method and 3D CFD calculations. Through the PFR calculations, it is found that the global mechanisms all predict a too early onset of fuel oxidation compared to the detailed mechanism. Furthermore, the global reference mechanism predicts gas concentrations more in line with the detailed mechanism than the oxy-fuel mechanisms, which yield incorrect reaction sequences. In the CFD analysis, significant differences in the predicted gas concentrations and temperature fields between the global mechanisms show that the choice of reaction mechanism strongly influences the results. In summary, the global reference mechanism is a preferable alternative to represent the combustion chemistry when modeling oxy-fuel combustion using CFD, if the use of a detailed reaction mechanism is prohibited due to computational limitations.
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| 35. |
- Horvath, Andrew T., et al.
(författare)
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Effect of Cross-Linking Fiber Joints on the Tensile and Fracture Behavior of Paper
- 2010
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 49:14, s. 6422-6431
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Tidskriftsartikel (refereegranskat)abstract
- The tensile and fracture properties of cross-linked paper were investigated at low and high relative humidity by cross-linking the joints formed between fibers. Cationic acetal dextran served as a model cross-linking agent, as it can be prepared to adsorb specifically to the fiber surface. Thus, cross-linking occurs only in the joints between fibers. The kinetics of hydrolysis was investigated to optimize the stock preparation, such that the resulting aldehyde groups react as the paper is dried. The effect of the cross-link density on the tensile and fracture properties was studied by varying the amount of acetal groups adsorbed to the pulp fibers. At low humidity, cross-linking improved the tensile and fracture properties of paper, although lower cross-link densities yielded better properties. Cross-linking was not effective at high relative humidty, as the tensile strength and stiffness were not improved. However, the fracture properties were significantly improved.
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| 36. |
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| 37. |
- Jilvero, Henrik, 1984, et al.
(författare)
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The Rate of CO2 Absorption in Ammonia-Implications on Absorber Design
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:16, s. 6750-6758
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Tidskriftsartikel (refereegranskat)abstract
- We propose design specifications and operating conditions for an absorber in an ammonia-based, post-combustion carbon capture process. We used a rate-based multistage column model to simulate a baseline-case scenario involving an absorber installed at a large-scale CO2 emission source. The goal was to exploit the chemistry of the NH3-CO2-H2O system to evaluate the performance of the absorber with respect to carbon capture, ammonia slip, and the height of the absorber. Thus, we identified as the two important prerequisites for absorber design: (1) that staged absorption is used and (2) that the rich CO2 loading does not exceed 0.5.
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| 38. |
- Jogunola, Olatunde, et al.
(författare)
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Reversible Autocatalytic Hydrolysis of Alkyl Formate : Kinetic and Reactor Modeling
- 2010
-
Ingår i: Industrial & Engineering Chemistry Research. - [Jogunola, Olatunde; Salmi, Tapio; Eranen, Karl; Warna, Johan; Kangas, Matias; Mikkola, J-P.] Abo Akad Univ, Proc Chem Ctr, Lab Ind Chem & React Engn, FI-20500 Turku, Finland. [Mikkola, J-P.] Umea Univ, Chem Biol Ctr, Dept Chem, SE-90187 Umea, Sweden. : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 49:9, s. 4099-4106
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Tidskriftsartikel (refereegranskat)abstract
- The kinetics and thermodynamics of alkyl formate hydrolysis in liquid phase were studied in a laboratory-scale autoclave at temperatures between 333 and 383 K using different molar ratios of the reactants. The process was found to exhibit an autocatalytic effect due to the acid formed. More so, the rate of neutral hydrolysis of ethyl formate is faster compared to methyl formate in the uncatalyzed reaction. However, the autocatalytic effect is more pronounced in methyl formate hydrolysis. In addition, the effect of adding a small amount of formic acid as an initial charge upon the equilibrium conversion and kinetics was investigated, and it was found that the addition improved the reaction rate by reducing the induction period but it suppressed slightly the equilibrium conversion. A kinetic model was proposed to explain these experimental trends, and the model agreed well with the experimental results.
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| 39. |
- Karlsson, Erik, 1983, et al.
(författare)
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Cleaning of Water-Soluble Scales in Black Liquor Evaporators – A Modeling Approach
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:50, s. 19600-19611
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Tidskriftsartikel (refereegranskat)abstract
- In the pulp and paper industry, the evaporation of black liquor is an important step to recover heat and chemicals. Due to a substantial amount of sodium carbonate and sodium sulfate in the black liquor, evaporators typically have to address the scaling of these water-soluble salts at concentrations above approximately 50% dry solids content. To maintain their operation, the evaporators are cleaned regularly using condensate or weak black liquor. In this paper, a model for evaporator cleaning was developed based on a dissolution model established via experimental measurements. Two new correlations for black liquor were also developed from experimental measurements: the solubility limit of sodium scales in black liquor and the density of black liquor containing additional dissolved salts. The simulations indicate high dissolution rates, meaning that the limiting step for the cleaning is the feed of free water with the wash liquid. The simulation results were insensitive to the distribution of scales, the mass transfer coefficient, and the temperature. However, the results were sensitive to the solubility limit and natural salt content for wash liquors above 30% dry solids content.
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| 40. |
- Karlsson, Erik, 1983, et al.
(författare)
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Solid Dissolution into a Vertical Falling Film under Industrial-like Conditions
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:22, s. 9478-9487
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Tidskriftsartikel (refereegranskat)abstract
- During the evaporation of black liquor, a residual stream in pulp mills, scales form on heat transfer surfaces due to the crystallization of sodium carbonate and sodium sulfate salts. As a result, falling film evaporators need regular cleaning to remove these water-soluble scales, and therefore, knowledge about the dissolution process is important. In this work, dissolution of the aforementioned salts was tested experimentally in a pilot evaporator close to the industrial scale. Dissolution was diffusion-controlled and could be described by film theory, where the concentration difference between the saturated wall and an assumed perfectly mixed bulk was the driving force of the process. The measured mass transfer coefficient could be predicted to within 30% accuracy using the Chilton-Colburn heat and mass transfer analogy together with a standard heat transfer correlation.
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| 41. |
- Kebede, Mebatsion L., et al.
(författare)
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Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Batch Operation Mode
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:41, s. 13445-13453
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Tidskriftsartikel (refereegranskat)abstract
- Solid supported evaporation (SSE) is a simple method to isolate dissolved compounds as a solid material. The solution is put in contact with granular porous polymer beads onto which the compounds deposit upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety and handling of the solids. In this paper, SSE in batch mode is explored where the solution is added to the polymer beads at once, i.e. opposite to the semicontinuous mode where the solution is sprayed over a bed of beads. A number of compounds varying widely in their physical and chemical properties is studied. It is found that all compounds could be loaded onto the beads; however, the loading capacity depends on the properties of the compound and in general was lower than in the semicontinuous operating mode studied in an accompanying paper. For highly soluble compounds, higher loadings could be achieved when solvent evaporation was slow. In cases where tested, bead loading was found to be homogeneous within a batch. Recovery of compound from loaded beads was achieved by dispersing the beads in a solvent and washing of the filter cake after filtration. A relatively large amount of solvent is required to achieve full recovery.
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| 42. |
- Leppäjärvi, Tiina, et al.
(författare)
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Maxwell-Stefan Modeling of Ethanol and Water Unary Pervaporation Through a High-silica MFI Zeolite Membrane
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:1, s. 323-332
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Tidskriftsartikel (refereegranskat)abstract
- The pervaporative mass transfer of pure ethanol and water through a thin (0.5 mu m) supported high-silica MFI membrane was studied experimentally at 30-70 degrees C, and modeled on the basis of the Maxwell-Stefan formalism. The temperature dependency of adsorption was described with the temperature dependency of pure component saturated vapor pressure. Two scenarios of coverage dependency, i.e., coverage-dependent and coverage-independent Maxwell-Stefan diffusivity, were applied in the modeling of the mass transfer through the zeolite film. In addition, the mass-transfer resistance of the support layers was taken into account. The derived unary models provided good representations of ethanol and water pervaporation flux. The study illustrates that pure component steady-state pervaporation flux measurements at different conditions offer a feasible basis for determining diffusion coefficients. Basically, pure component adsorption isotherms and derived diffusivities can be used in the modeling of pervaporative mass transfer of mixtures using zeolite membranes.
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| 43. |
- Lind, Fredrik, 1978, et al.
(författare)
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Continuous Catalytic Tar Reforming of Biomass Derived Gas with Simultaneous Catalyst Regeneration
- 2011
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 50:20, s. 11553-11562
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Tidskriftsartikel (refereegranskat)abstract
- A novel concept for secondary catalytic tar cleaning with simultaneous regeneration of the catalysts is presented in this work. The process is demonstrated by an initial experiment with producer gas from the Chalmers biomass gasifier using ilmenite (FeTiO3) as catalytic bed material. The tar cleaning system was operated at 800 °C and fed with raw gas from the Chalmers biomass gasifier, in which silica sand was used as bed material and the gasification was performed with steam. The tar content of the gas emerging from the gasifier was roughly 30 gtar/Nm3gas. The experiment showed that the catalyst was continuously regenerated from carbon deposits and the ilmenite reduced the total amount of tar by 35% at a gas residence time in the bed of 0.4 – 0.5 s. Branched hydrocarbons and phenols were more or less completely reformed, while there was an increase of stable aromatic rings (benzene, naphthalene). The catalyst showed high activity in water-gas shift reactions and the H2/CO ratio was shifted from around 0.7 prior to the reactor to almost 3 after the reactor.
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| 44. |
- Lund, Kristoffer, 1983, et al.
(författare)
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Kinetics of Cross-Linking Softwood Kraft Pulp with 1,2,3,4-Butanetetracarboxylic Acid
- 2013
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:33, s. 11502-11509
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Tidskriftsartikel (refereegranskat)abstract
- Cross-linking of polysaccharides has been well studied in both the pulp and textile industries. One of the more investigated cross-linking agents is 1,2,3,4-butanetetracarboxylic acid (BTCA). The intrafiber cross-linking of cotton cellulose with BTCA has attracted great interest. In the case of wood pulp, reaction kinetics has been studied relatively little; instead, investigations have focused on fiber and paper properties. In this study, softwood kraft pulp fibers were cross-linked with BTCA, and the kinetics of the reaction was investigated and modeled. It was found that the reaction follows second-order kinetics, dependent on both the concentration of BTCA and the concentration of accessible hydroxyl groups in the fiber wall. It was further found that the initial concentration of accessible hydroxyl groups was proportional to the initial concentration of BTCA, thus simplifying the model into a second-order rate equation dependent only on the concentration of BTCA. A cross-linking reaction was confirmed by performing conductometric titration.
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| 45. |
- Mellin, Pelle, et al.
(författare)
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Simulation of Bed Dynamics and Primary Products from Fast Pyrolysis of Biomass : Steam Compared to Nitrogen as a Fluidizing Agent
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:30, s. 12129-12142
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Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis of biomass, using steam as a fluidizing agent, provides several benefits. In this paper, an unsteady multiphase computational fluid dynamics (CFD) model coupled with a comprehensive kinetic scheme for primary pyrolysis is used to obtain the formation rates of primary products and compare the profiles when operating with steam and nitrogen. The model only considers the physical effects of the fluidizing gas at the moment, although a literature review indicates the existence of various chemical and surface-interacting effects. At stabilized pyrolysis reaction rates, the product yields were compared to data found in the literature, which indicated similar yields; this supports the correct implementation of the kinetic model. However, the difference in overall rate and composition is very small when steam is compared to nitrogen. The simultaneous simulation of bed dynamics indicate a shifted formation rate of primary products toward the lower part of the fluidized bed, with an increase in solid vapor contact time and better temperature distribution as a result. More specifically, total heat flux to the biomass increased by 1396 in the lowest part of the reactor. In addition, more heat from the sand is carried through the gas phase when using steam: an increase by 9% in the overall reactor (25% in the lowest part), as indicated by the results. Finally, since no substantial differences in overall product formation rate and composition were found, the considerable effect of steam found in experiments and the literature is mainly (not exclusively) attributed to the chemical and surface-interacting mechanisms. Because of the complex nature of secondary pyrolysis in this process, a comprehensive gas-phase kinetic model is needed to investigate the effects of steam further. Coupling of both is difficult, because of computational constraints, as the present model already is very demanding. The obtained profiles of formation rate of primary products can however be used as an input to another model specifically made for studying homogeneous secondary pyrolysis reactions.
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| 46. |
- Mustafa, Arwa, et al.
(författare)
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Evaluation of Oxidation Stability of Refined Mineral Oil Enriched with Carotenoids from Carrot Using Supercritical Carbon Dioxide Extraction
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:49, s. 19028-19033
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Tidskriftsartikel (refereegranskat)abstract
- Refined mineral oil, intended for various technical applications, was enriched with carotenoids by supercritical carbon dioxide extraction using the oil itself as cosolvent. It was envisioned that the carotenoids could function as renewable oil additives, adding chemical functionality to the end product such as enhanced resistance to oxidation. In order to investigate such possible antioxidant activity, a testing protocol was developed in which oil samples were thermally aged in the presence of a controlled amount of oxygen, and the time-dependent hydroperoxide and keto functionality concentration was monitored. An indication of antioxidant activity was indeed found, and further experiments were undertaken in order to investigate whether this was caused by the main carotenoid found in carrots, beta-carotene. This was not found to be the case, and other possible explanations for the observed oxidative behavior, still to be investigated, are discussed.
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| 47. |
- Mutturi, Sarma, et al.
(författare)
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Effect of Temperature on Simultaneous Saccharification and Fermentation of Pretreated Spruce and Arundo
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:3, s. 1244-1251
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Tidskriftsartikel (refereegranskat)abstract
- A critical factor in simultaneous saccharification and fermentation (SSF) is the selection of process temperature, which needs to be a compromise between the optimal temperature for enzymatic hydrolysis and that for fermentation. In the present work, isothermal and nonisothermal SSF was experimentally studied using pretreated spruce and arundo materials at a loading of 10% water insoluble solids, with an industrial strain of Saccharomyces cerevisiae as the fermenting organism. In the nonisothermal experiments, the temperatures were linearly increased during the batch time of 96 h, and the results were compared to isothermal SSF operation. The final ethanol concentrations obtained for the arundo material was 16.5 g/L in the nonisothermal process using an initial temperature of 32 degrees C and a linearly increasing temperature of 0.135 degrees C/h. As a comparison, the final ethanol concentration obtained was 13.4 g/L for an isothermal operation at 32 degrees C and 15.3 g/L for an isothermal process running at 39 degrees C. The corresponding values for the spruce material were 33.1 g/L, and 29.1 g/L and 32.2 g/L, for nonisothermal and isothermal operation at 32 and 39 degrees C, respectively. The obtained ethanol yields, in particular for the case of arundo, demonstrate that nonisothermal SSF operation can give increased ethanol yields in comparison to isothermal SSF.
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| 48. |
- Nicholls, Ian A., et al.
(författare)
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Computational Strategies for the Design and Study of Molecularly Imprinted Materials
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:39, s. 13900-13909
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Tidskriftsartikel (refereegranskat)abstract
- The need for materials with predetermined ligand-selectivities for use in sensing and separation technologies, e.g. membranes and chromatography, has driven the development of molecularly imprinted polymer science and technology. Over recent years, the need to develop robust predictive tools capable of handling the complexity of molecular imprinting systems has become apparent The current status of the use of in silica techniques in molecular imprinting is here presented, and we highlight areas where new developments are contributing to improvements in the rational design of molecularly imprinted polymers.
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| 49. |
- Nilsson, Fritjof, et al.
(författare)
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Predicting Solubility and Diffusivity of Gases in Polymers under High Pressure : N-2 in Polycarbonate and Poly(ether-ether-ketone)
- 2013
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 52:26, s. 8655-8663
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to develop a model that predicts the gas solubility and the sorption and desorption kinetics in polymer granulates over large temperature and pressure intervals. Besides the part predicting the solubility and diffusivity, the model involves the simultaneous solution of the diffusion equation and the heat equation in three dimensions using a finite element method (FEM). When the temperature- and pressure-dependent solubility of a specific polymer/gas combination is not known, an improved version of the non-equilibrium lattice fluid model (NELF) is used to predict the solubility. The improvement of the NELF model includes the use of Hansen's solubility parameters, and it uses pressure-volume-temperature (PVT) data from two new empirical models, which accurately estimate polymer densities over a wide range of temperatures and pressures. The new solubility model predicted the solubility-pressure data of N-2 in poly(ethyl methacrylate) and N-2 and CH4 in polycarbonate (PC) at pressures below 4.5 MPa, without using any adjustable interaction parameters. The model was used to predict the solubility of N-2 in poly(ether-ether-ketone) (PEEK) and PC at a very high pressure (67 MPa). Experimental N-2 solubility data were obtained with a specially built reactor yielding high pressure and temperature. For PEEK, it was possible to predict the very high pressure solubility using a gas-polymer interaction parameter obtained from data taken at low pressures In addition, a new free-volume-based diffusivity model requiring no adjustable interaction parameters was developed, and it successfully predicted the desorption kinetics of N-2 from PEEK and PC.
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| 50. |
- Norgren, Magnus, et al.
(författare)
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Lignin Removal by Adsorption to Fly Ash in Wastewater Generated by Mechanical Pulping
- 2012
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 51:8, s. 3444-3451
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Tidskriftsartikel (refereegranskat)abstract
- Stringent discharge requirements call for advanced methods of wastewater treatment to take on where biological treatment fails to succeed. Here, the adsorption potential of fly ash, an on-site available and cheap material, was tested in batch and continuous flow fixed bed experiments using bleaching effluent from an integrated mill producing mechanical pulp. Various models were fitted to the experimental data to find the best description of the adsorption system and to obtain important model parameters: the Freundlich model yielded the highest correlation and indicated that the process was favorable. The bed depth service time model suggested that the adsorption in the column setup involved more than one rate limiting step, and the Thomas and Clark models generated similar curves which satisfactorily described adsorption at short bed depth. The fly ash showed good adsorptive properties of wood derived substances: both lignin and extractives were effectively separated from the effluent.
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