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William J Koros - One of the best experts on this subject based on the ideXlab platform.
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stabilization of porous morphologies for high performance carbon molecular Sieve hollow fiber membranes
2012Co-Authors: Nitesh Bhuwania, William J Koros, Paul Jason WilliamsAbstract:Carbon molecular Sieves (CMS) membranes having improved thermal and/or mechanical properties are disclosed herein. In one embodiment, a carbon molecular Sieve membrane for separating a first and one or more second gases from a feed mixture of the first gas and one or more second gases comprises a hollow filamentary carbon core and a thermally stabilized polymer precursor disposed on at least an outer portion of the core. In some embodiments, the thermally stabilized polymer precursor is created by the process of placing in a reaction vessel the carbon molecular Sieve membrane comprising an unmodified aromatic imide polymer, filling the reaction vessel with a modifying agent, and changing the temperature of the reaction vessel at a temperature ramp up rate and ramp down rate for a period of time so that the modifying agent alters the unmodified aromatic imide polymer to form a thermally stabilized polymer precursor.
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effect of processing on carbon molecular Sieve structure and performance
Carbon, 2010Co-Authors: Mita Das, John D. Perry, William J KorosAbstract:Sub-micron sized carbon molecular Sieve (CMS) materials were produced via ball milling for subsequent use in hybrid material formation. A detailed analysis of the effects of the milling process in the presence of different milling environments is reported. The milling process apparently alters the molecular scale structure and properties of the carbon material. Three cases: unmilled, air milled and nitrogen milled, were analyzed in this work. The property changes were probed using equilibrium sorption experiments with different gases. Furthermore, WAXD and BET results also showed differences between milling processes. Finally in order to improve the interfacial polymer-Sieve region of hybrid membranes, the CMS surface was chemically modified with a linkage unit capable of covalently bonding the polymer to the Sieve. A published single-wall carbon nanotube (SWCNTs) modification method was adopted to attach a primary aromatic amine to the surface. Several aspects including rigidity, chemical composition, bulky groups and length were considered in selecting the preferred linkage unit. Fortunately kinetic and equilibrium sorption properties of the modified Sieves showed very little difference from unmodified samples, suggesting that the linkage unit is not excessively filling or obstructing access to the pores of the CMSs during the modification process.
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gas transport property performance of hybrid carbon molecular Sieve polymer materials
Industrial & Engineering Chemistry Research, 2010Co-Authors: Mita Das, John D. Perry, William J KorosAbstract:High-performance hybrid materials using carbon molecular Sieve materials and 6FDA−6FpDA were produced. A detailed analysis of the effects of casting processes and the annealing temperature is reported. Two existing major obstacles, Sieve agglomeration and residual stress, were addressed in this work, and subsequently a new membrane formation technique was developed to produce high-performing membranes. The successfully improved interfacial region of the hybrid membranes allows the Sieves to increase the selectivity of the membranes above the neat polymer properties. Furthermore, an additional performance enhancement was seen with increased Sieve loading in the hybrid membranes, leading to an actual performance above the upper bound for pure polymer membranes. The membranes were also tested under a mixed-gas environment, which further demonstrated promising results.
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challenges in forming successful mixed matrix membranes with rigid polymeric materials
Journal of Applied Polymer Science, 2002Co-Authors: Rajiv Mahajan, Michael Schaeffer, Ryan L Burns, William J KorosAbstract:Mixed matrix materials comprised of molecular Sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane materials. It has been shown that successful mixed matrix materials can be formed using relatively low glass transition (Tg) polymers that have a favorable interaction with the Sieves. This article extends this earlier work to include the use of more practical rigid matrix polymers with high Tgs that can ultimately be used in forming high-performance mixed matrix layers for composite membranes. Initial attempts to form mixed matrix materials based on high Tg polymers with a type 4A zeolite resulted in poor adhesion between the polymer and Sieve. Correcting this problem was pursued in this study by forming the composite material close to the Tg of the polymer by addition of a plasticizer to match the matrix Tg with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A–Matrimid®/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 881–890, 2002
Keshun Liu - One of the best experts on this subject based on the ideXlab platform.
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effects of particle size distribution compositional and color properties of ground corn on quality of distillers dried grains with solubles ddgs
Bioresource Technology, 2009Co-Authors: Keshun LiuAbstract:Oftentimes, corn processors believe that ground corn (raw material) and distillers dried grains with solubles (DDGS) are interrelated in certain quality parameters. Yet, previous studies, although rather limited, have not established this relationship. In this study, six ground corn samples and their resulting DDGS were analyzed for particle size distribution (PSD), using a series of six selected US standard Sieves: Nos. 8, 12, 18, 35, 60, and 100, and a pan. The original sample and Sieve sized fractions were measured for contents of moisture, protein, oil, ash and starch, and surface color. Total carbohydrate (CHO) and total non-starch CHO were also calculated. Results show that the geometric mean diameter (dgw) of particles varied with individual corn and DDGS samples, and that dgw of DDGS was larger than that of corn (0.696 vs. 0.479 mm, average values), indicating that during conversion of corn to DDGS, certain particles became enlarged. For dgw and mass frequency of individual particle size classes, the relationship between ground corn and DDGS varied, but PSD of the whole sample was well correlated between them (r = 0.807). Upon conversion from corn to DDGS, on an average, protein was concentrated 3.59 times; oil, 3.40 times; ash, 3.32 times; and total non-starch CHO, 2.89 times. There were some positive correlations in contents of protein and non-starch CHO and in L value between corn and DDGS. Yet, variations in nutrients and color attributes were larger in DDGS than in corn. For either corn or DDGS, these variations were larger in Sieved fractions than in the whole fraction. Raw material, processing method and addition of yeasts are among major factors considered for causing larger variations in these attributes among DDGS. The study partially supports the common belief by processors that quality attributes of corn affect those of DDGS. Published by Elsevier Ltd.
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particle size distribution of distillers dried grains with solubles ddgs and relationships to compositional and color properties
Bioresource Technology, 2008Co-Authors: Keshun LiuAbstract:Abstract Eleven distillers dried grains with solubles (DDGS), processed from yellow corn, were collected from different ethanol processing plants in the US Midwest area. Particle size distribution (PSD) by mass of each sample was determined using a series of six selected US standard Sieves: Nos. 8, 12, 18, 35, 60, and 100, and a pan. The original sample and Sieve sized fractions were measured for surface color and contents of moisture, protein, oil, ash, and starch. Total carbohydrate (CHO) and total non-starch CHO were also calculated. Results show that there was a great variation in composition and color among DDGS from different plants. Surprisingly, a few DDGS samples contained unusually high amounts of residual starch (11.1–17.6%, dry matter basis, vs. about 5% of the rest), presumably resulting from modified processing methods. Particle size of DDGS varied greatly within a sample and PSD varied greatly among samples. The 11 samples had a mean value of 0.660 mm for the geometric mean diameter ( d gw ) of particles and a mean value of 0.440 mm for the geometric standard deviation ( S gw ) of particle diameters by mass. The majority had a unimodal PSD, with a mode in the size class between 0.5 and 1.0 mm. Although PSD and color parameters had little correlation with composition of whole DDGS samples, distribution of nutrients as well as color attributes correlated well with PSD. In Sieved fractions, protein content, L and a color values negatively while contents of oil and total CHO positively correlated with particle size. It is highly feasible to fractionate DDGS for compositional enrichment based on particle size, while the extent of PSD can serve as an index for potential of DDGS fractionation. The above information should be a vital addition to quality and baseline data of DDGS.
Mita Das - One of the best experts on this subject based on the ideXlab platform.
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effect of processing on carbon molecular Sieve structure and performance
Carbon, 2010Co-Authors: Mita Das, John D. Perry, William J KorosAbstract:Sub-micron sized carbon molecular Sieve (CMS) materials were produced via ball milling for subsequent use in hybrid material formation. A detailed analysis of the effects of the milling process in the presence of different milling environments is reported. The milling process apparently alters the molecular scale structure and properties of the carbon material. Three cases: unmilled, air milled and nitrogen milled, were analyzed in this work. The property changes were probed using equilibrium sorption experiments with different gases. Furthermore, WAXD and BET results also showed differences between milling processes. Finally in order to improve the interfacial polymer-Sieve region of hybrid membranes, the CMS surface was chemically modified with a linkage unit capable of covalently bonding the polymer to the Sieve. A published single-wall carbon nanotube (SWCNTs) modification method was adopted to attach a primary aromatic amine to the surface. Several aspects including rigidity, chemical composition, bulky groups and length were considered in selecting the preferred linkage unit. Fortunately kinetic and equilibrium sorption properties of the modified Sieves showed very little difference from unmodified samples, suggesting that the linkage unit is not excessively filling or obstructing access to the pores of the CMSs during the modification process.
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gas transport property performance of hybrid carbon molecular Sieve polymer materials
Industrial & Engineering Chemistry Research, 2010Co-Authors: Mita Das, John D. Perry, William J KorosAbstract:High-performance hybrid materials using carbon molecular Sieve materials and 6FDA−6FpDA were produced. A detailed analysis of the effects of casting processes and the annealing temperature is reported. Two existing major obstacles, Sieve agglomeration and residual stress, were addressed in this work, and subsequently a new membrane formation technique was developed to produce high-performing membranes. The successfully improved interfacial region of the hybrid membranes allows the Sieves to increase the selectivity of the membranes above the neat polymer properties. Furthermore, an additional performance enhancement was seen with increased Sieve loading in the hybrid membranes, leading to an actual performance above the upper bound for pure polymer membranes. The membranes were also tested under a mixed-gas environment, which further demonstrated promising results.
Jacek Klinowski - One of the best experts on this subject based on the ideXlab platform.
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oxidation of volatile organic compounds on sba 15 mesoporous molecular Sieves modified with manganese
Chemosphere, 2009Co-Authors: Alexander Orlov, Jacek KlinowskiAbstract:Abstract Catalytic combustion of volatile organic compounds, such as propene, has been studied on manganese modified mesoporous molecular Sieves. Powder X-ray diffraction, 29 Si nuclear magnetic resonance, nitrogen sorption and transmission electron microscopy show that the SBA-15 mesoporous silica molecular Sieve can be modified with manganese using Mn 2 (CO) 10 or Mn(O 2 CMe) 2 without significant distortion of the host structure. The two products were catalytically active in propene oxidation, with SBA-15 modified with Mn 2 (CO) 10 showing significantly higher activity, possibly due to higher Mn content, than SBA-15 modified with Mn(O 2 CMe) 2 .
Sun Yuhan - One of the best experts on this subject based on the ideXlab platform.
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preparation method of high performance sapo silicoaluminophosphate 34 molecular Sieve membrane
2014Co-Authors: Zhang Yanfeng, Li Meng, Sun YuhanAbstract:The invention discloses a preparation method of a high-performance SAPO (silicoaluminophosphate)-34 molecular Sieve membrane. The preparation method comprises the following steps: (1) obtaining an SAPO-34 molecular Sieve crystal seed; (2) coating the SAPO-34 molecular Sieve crystal seed on the inner surface of a porous carrier; (3) putting the prepared porous carrier coated with the SAPO-34 molecular Sieve crystal seed into synthesizing mother liquor of the molecular Sieve membrane and synthesizing an SAPO-34 molecular Sieve membrane tube; (4) roasting to remove a template agent, thereby obtaining the SAPO-34 molecular Sieve membrane without the template agent. The preparation method disclosed by the invention has the advantages that the uniformity and stability of the synthesizing mother liquid are greatly improved, the synthesis repeatability of the SAPO-34 molecular Sieve membrane is improved, and the synthesized SAPO-34 molecular Sieve membrane has higher gas permeability and CO2/CH4 selectivity. Furthermore, the SAPO-34 molecular Sieve membrane prepared by the preparation method can be applied to gas separation of CO2-CH4, CO2-H2 and CO2/N2 and the like.
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method for preparing high performance molecular Sieve membrane through ion exchange at melting state
2014Co-Authors: Zhang Yanfeng, Li Meng, Sun YuhanAbstract:The invention discloses a method for preparing a high-performance molecular Sieve membrane through ion exchange at a melting state. The method comprises the steps of loading metal salt with the melting point being lower than a roasting temperature onto a molecular Sieve membrane with a template agent being removed, drying the molecular Sieve membrane, and carrying out melting-state ion exchange under the situation that the temperature is lower than the roasting temperature and higher than the melting point of metal salt to obtain the ion exchange molecular Sieve membrane, wherein the roasting temperature is generated when the template agent in the molecular Sieve membrane is removed. By the method, the CO2/CH4 selectivity of the molecular Sieve membrane can be remarkably improved.
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nano sapo silicoaluminophosphate 34 molecular Sieve with spherical or flaky appearance synthetic method thereof catalyst prepared by same and application thereof
2013Co-Authors: Sun Yuhan, Wu Lei, Liu Ziyu, Xia Lin, Qiu Minghuang, Liu Xu, Zhu Haojia, Sun Zhiqiang, Liu Bin, Wang DongfeiAbstract:The invention discloses a nano SAPO (silicoaluminophosphate)-34 molecular Sieve with a spherical or flaky appearance, a synthetic method of the nano SAPO-34 molecular Sieve and a methanol to olefin catalyst prepared by the molecular Sieve. The SAPO-34 molecular Sieve is prepared in a microwave heating manner. The nano spherical or flaky SAPO-34 molecular Sieve can be obtained by controlling microwave synthesis conditions, is a sphere having a crystal grain size less than 30nm or a sheet having a thickness less than 70nm, and the has the characteristics of short synthetic time, controllable crystal grain appearance and the like. A molecular Sieve catalyst prepared by the molecular Sieve is used for reactions of methanol to olefin, such as methanol to ethylene, methanol to propylene and the like, wherein a methanol conversion rate can reach 100%, the selectivity of C2 to C4 can reach 89.85%, the single pass life of the catalyst can reach 350 minutes.
