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Hiroshi Uyama - One of the best experts on this subject based on the ideXlab platform.
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Hierarchical silica Monolith prepared using cellulose Monolith as template
Polymer Degradation and Stability, 2020Co-Authors: Taka-aki Asoh, Hiroshi UyamaAbstract:Abstract Silica Monoliths with a continuous porous structure have received much attention in biomedical and environmental applications owing to their high-performance separation/adsorption behaviors. However, it is difficult to maintain a porous structure in silica Monoliths because their synthesis often involves complicated phase separation in sol-gel reactions. Herein, for the first time, we used an ecofriendly cellulose material as a template to prepare a hydrophilic and hierarchically porous silica Monolith. The cellulose Monolith template was prepared from cellulose acetate by a thermally induced phase separation method. The silica was then prepared in the presence of the cellulose Monolith by a typical sol-gel reaction of tetraethyl orthosilicate (TEOS) to form the composite Monolith, which was converted to the silica Monolith by burning in air to remove the cellulose Monolith. Owing to the hierarchically porous structure of the cellulose Monolith template, the obtained silica Monolith showed a similar hierarchically porous structure, as confirmed by scanning electron microscopy and nitrogen adsorption-desorption analyses. The pore structure could be controlled by changing the fabrication parameters, such as the kind of cellulose Monolith and TEOS concentration. The surface-modified silica Monolith was developed for further applications.
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phase separation approach to a reactive polycarbonate Monolith for click modifications
Polymer, 2015Co-Authors: Junji Sakamoto, Andre J Van Der Vlies, Urara Hasegawa, Hiroshi UyamaAbstract:Abstract A new polycarbonate Monolith carrying allyl groups has been introduced. The Monolith was fabricated via the phase separation induced by adding cyclohexane to a solution of the polymer in chloroform. Cross-sectional analysis of the Monolith was performed by scanning electron microscopy that unveiled a three-dimensionally networked porous structure inside the Monolith. As a result of nitrogen adsorption/desorption experiments, the specific surface area of the Monolith was calculated to be 145 m 2 /g with the Brunauer Emmett Teller equation. The allyl groups of the Monolith were subjected to a thiol-ene click reaction with 2-mercaptoethanol and an olefin metathesis with a Grubbs catalyst. With the porous structure largely maintained, the click reaction attained high conversions and the metathesis internally crosslinked the Monolith to the degree that confers solvent resistance. These results qualify the present Monolith as a versatile platform for chemical transformations into a wide range of functional Monoliths.
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facile fabrication of poly methyl methacrylate Monolith via thermally induced phase separation by utilizing unique cosolvency
Polymer, 2014Co-Authors: Shinya Yoneda, Urara Hasegawa, Hiroshi UyamaAbstract:Abstract Poly(methyl methacrylate) (PMMA) Monoliths with a three-dimensional continuous interconnected porous structure in a single piece were fabricated via thermally induced phase separation (TIPS) by utilizing unique cosolvency toward PMMA. We found that PMMA was soluble in a mixture of non-solvents (ethanol and water) at 60 °C. Cooling the solution resulted in formation of a Monolith having interconnected pores. Cross-sectional analysis using scanning electron microscopy (SEM) showed a continuous porous network with submicron-sized skeleton. The pore size of the Monolith was readily controlled by varying the fabrication parameters such as the polymer concentration and molecular weight, the cooling temperature and the solvent composition. The cross-section of the Monolith showed high water repellency. The PMMA Monolith was also obtained in a mixture of isopropanol and water with an appropriate solvent ratio.
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Adsorption over polyacrylonitrile based carbon Monoliths
2013Co-Authors: Mahasweta Nandi, Arghya Dutta, Astam K. Patra, Asim Bhaumik, Hiroshi UyamaAbstract:Highly porous activated carbon Monoliths have been prepared from mesoporous polyacrylonitrile (PAN) Monolith as the carbon precursor. The mesoporous PAN Monoliths are fabricated by a unique and facile template-free method which on carbonization gives N-doped activated carbon Monoliths. The carbonization is achieved via two step thermal process which includes pretreatment in air leading to cyclization and subsequent aromatization of the PAN moieties followed by carbonization in a mixture of argon and carbon dioxide to give a layered carbon framework. Nitrogen sorption experiments carried over these carbon Monoliths revealed high surface area (ca. 2500 m2g−1) for these materials with precise micropore size distribution. The activated carbons show extraordinarily high CO2 capture capacity and the uptake up to 3 bar has been found to be as high as 22.5 and 10.6 mmol/g at 273 K and 298 K, respectively.
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facile fabrication of polycarbonate Monolith by non solvent induced phase separation method
Polymer, 2012Co-Authors: Takashi Fujimoto, Hiroshi UyamaAbstract:Abstract Polycarbonate (PC) Monoliths with three-dimensional continuous interconnected porous structure in a single piece are fabricated via non-solvent induced phase separation (NIPS) for the first time. The morphology of fabricated Monolith is observed through SEM, the surface area is determined by BET method and the thermal property is measured via DSC. The pore and skeleton sizes of the Monolith are readily controlled by varying the fabrication parameters such as the polymer concentration and molecular weight, the standing temperature and the solvent composition. The PC Monolith possesses relatively large surface area and sharp melting point at 232 °C. These Monoliths with high thermal stability can offer various potential applications of functional materials.
A. Bueno-lópez - One of the best experts on this subject based on the ideXlab platform.
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NOx reduction to N2 with commercial fuel in a real diesel engine exhaust using a dual bed of Pt/beta zeolite and RhOx/ceria Monolith catalysts
Chemical Engineering Science, 2013Co-Authors: V. Rico-pérez, J. M. García-cortés, C. Salinas Martínez De Lecea, A. Bueno-lópezAbstract:Abstract The Selective Catalytic Reduction (SCR) of NOx has been performed in a real diesel engine exhaust using commercial diesel fuel as a reducing agent and a dual bed catalytic system consisting of a Pt/beta zeolite/honeycomb Monolith SCR catalyst located upstream a N2O decomposition RhOx/Ce0.9Pr0.1O2/honeycomb Monolith catalyst. Cordierite honeycomb Monoliths (diameter 2.3 cm; length 7.5 cm; 400 cpsi) were washcoated with beta zeolite and 1% platinum (on zeolite basis) was impregnated afterwards. The effect of the beta zeolite slurry viscosity on the dip-coating process was studied in detail, concluding that slurries with viscosity ≤23 mPa s must be used, otherwise the zeolite suspension was not able to penetrate into the Monolith channels. The dip-coating method was optimized for the Pt/beta zeolite/honeycomb Monolith preparation. The RhOx/Ce0.9Pr0.1O2/honeycomb Monolith catalyst, used for N2O decomposition, was prepared by nitrate precursor decomposition. The maximum NOx removal achieved with the Pt/beta zeolite/honeycomb Monolith was 50% at 350 °C. The production of N2O as undesired NOx reduction product, which is a drawback of platinum SCR catalysts, has been solved by using the dual bed configuration, where both Monolith catalysts operated at the same temperature, and 100% N2 selectivity has been obtained.
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NOx reduction to N2with commercial fuel in a real diesel engine exhaust using a dual bed of Pt/beta zeolite and RhOx/ceria Monolith catalysts
Chemical Engineering Science, 2013Co-Authors: V. Rico-pérez, J. M. García-cortés, C. Salinas Martínez De Lecea, A. Bueno-lópezAbstract:The Selective Catalytic Reduction (SCR) of NOx has been performed in a real diesel engine exhaust using commercial diesel fuel as a reducing agent and a dual bed catalytic system consisting of a Pt/beta zeolite/honeycomb Monolith SCR catalyst located upstream a N2O decomposition RhOx/Ce0.9Pr0.1O2/honeycomb Monolith catalyst. Cordierite honeycomb Monoliths (diameter 2.3cm; length 7.5cm; 400cpsi) were washcoated with beta zeolite and 1% platinum (on zeolite basis) was impregnated afterwards. The effect of the beta zeolite slurry viscosity on the dip-coating process was studied in detail, concluding that slurries with viscosity ≤23mPas must be used, otherwise the zeolite suspension was not able to penetrate into the Monolith channels. The dip-coating method was optimized for the Pt/beta zeolite/honeycomb Monolith preparation. The RhOx/Ce0.9Pr0.1O2/honeycomb Monolith catalyst, used for N2O decomposition, was prepared by nitrate precursor decomposition. The maximum NOx removal achieved with the Pt/beta zeolite/honeycomb Monolith was 50% at 350°C. The production of N2O as undesired NOx reduction product, which is a drawback of platinum SCR catalysts, has been solved by using the dual bed configuration, where both Monolith catalysts operated at the same temperature, and 100% N2selectivity has been obtained. © 2013 Elsevier Ltd.
Tobias Bauer - One of the best experts on this subject based on the ideXlab platform.
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Liquid saturation and gas–liquid distribution in multiphase Monolithic reactors
Chemical Engineering Science, 2005Co-Authors: Tobias Bauer, Ruediger Lange, Muthanna Al-dahhanAbstract:Abstract The Monolith bed is one of the promising catalytic reactors for a number of chemical gas–liquid–solid processes. In the present work, liquid saturations for five different Monoliths have been investigated experimentally in a cold-flow unit with a reactor diameter of 5.0 cm. The influences of gas and liquid flow rates and of the direction of two-phase flow on liquid saturation were examined. The results indicate that the direction of flow has no significant influence on liquid saturation for proper gas–liquid distribution. The experimental results are in good agreement with predictions of the drift flux model using the distribution parameter proposed by Ishii (ANL Report ANL-77-47, 1977) along with the assumption of zero drift velocity. In preliminary experiments, gamma-ray computed tomography (CT) has been successfully applied to measure time-averaged liquid distribution over the Monolith cross-section in a selected condition. The employment of a nozzle-type distributor provides an almost uniform liquid distribution over the Monolith substrate. It is demonstrated that CT is a viable technique for studying two-phase flow in laboratory-scale Monolith reactors.
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liquid saturation and gas liquid distribution in multiphase Monolithic reactors
Chemical Engineering Science, 2005Co-Authors: Tobias Bauer, Ruediger Lange, Muthanna H AldahhanAbstract:Abstract The Monolith bed is one of the promising catalytic reactors for a number of chemical gas–liquid–solid processes. In the present work, liquid saturations for five different Monoliths have been investigated experimentally in a cold-flow unit with a reactor diameter of 5.0 cm. The influences of gas and liquid flow rates and of the direction of two-phase flow on liquid saturation were examined. The results indicate that the direction of flow has no significant influence on liquid saturation for proper gas–liquid distribution. The experimental results are in good agreement with predictions of the drift flux model using the distribution parameter proposed by Ishii (ANL Report ANL-77-47, 1977) along with the assumption of zero drift velocity. In preliminary experiments, gamma-ray computed tomography (CT) has been successfully applied to measure time-averaged liquid distribution over the Monolith cross-section in a selected condition. The employment of a nozzle-type distributor provides an almost uniform liquid distribution over the Monolith substrate. It is demonstrated that CT is a viable technique for studying two-phase flow in laboratory-scale Monolith reactors.
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Liquid saturation and gas-liquid distribution in multiphase Monolithic reactors
Chemical Engineering Science, 2005Co-Authors: Tobias Bauer, Shaibal Roy, Ruediger Lange, Muthanna Al-dahhanAbstract:The Monolith bed is one of the promising catalytic reactors for a number of chemical gas-liquid-solid processes. In the present work, liquid saturations for five different Monoliths have been investigated experimentally in a cold-flow unit with a reactor diameter of 5.0 cm. The influences of gas and liquid flow rates and of the direction of two-phase flow on liquid saturation were examined. The results indicate that the direction of flow has no significant influence on liquid saturation for proper gas-liquid distribution. The experimental results are in good agreement with predictions of the drift flux model using the distribution parameter proposed by Ishii (ANL Report ANL-77-47, 1977) along with the assumption of zero drift velocity. In preliminary experiments, gamma-ray computed tomography (CT) has been successfully applied to measure time-averaged liquid distribution over the Monolith cross-section in a selected condition. The employment of a nozzle-type distributor provides an almost uniform liquid distribution over the Monolith substrate. It is demonstrated that CT is a viable technique for studying two-phase flow in laboratory-scale Monolith reactors. © 2005 Elsevier Ltd. All rights reserved.
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Monoliths as multiphase reactors: A review
Aiche Journal, 2004Co-Authors: Tobias Bauer, Muthanna H. Al-dahhan, Peter Lehner, Thomas TurekAbstract:Monolith reactors are being studied as a replacement for conventional multiphase reactors such as trickle-bed reactors, slurry reactors, and slurry bubble column reactors for gas–liquid–solid reactions. Reactors with Monolith catalyst packing have been found to be hydrodynamically superior to existing industrial reactors. This review covers multiphase reactions carried out in Monolith reactors by various researchers. It first defines the Monolith reactor and looks into the geometrical aspects of Monolith. The section dealing with hydrodynamics reviews pressure drop, phase holdup, flow distribution, and dispersion characteristics. This study also considers the tools used to characterize the hydrodynamic parameters and their typical values. Although the available literature is scarce, Monoliths are considered to have superior mass transfer characteristics. This review lists the mass transfer correlations for each category (gas–liquid, gas–solid, liquid–solid). The last section discusses the reaction aspects of Monolith reactors. The ultimate goal is to implement such reactors for multiphase reactions. This section also compares the performance of Monolith reactors with conventional multiphase reactors and lists the various reactor models reported to predict the overall performance of Monolith reactors. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2918–2938, 2004
Jing Dong - One of the best experts on this subject based on the ideXlab platform.
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facile construction of macroporous hybrid Monoliths via thiol methacrylate michael addition click reaction for capillary liquid chromatography
Journal of Chromatography A, 2015Co-Authors: Junjie Ou, Hongwei Wang, Jing DongAbstract:Abstract A facile approach based on thiol-methacrylate Michael addition click reaction was developed for construction of porous hybrid Monolithic materials. Three hybrid Monoliths were prepared via thiol-methacrylate click polymerization by using methacrylate-polyhedral oligomeric silsesquioxane (POSS) (cage mixture, n = 8, 10, 12, POSS-MA) and three multi-thiol crosslinkers, 1,6-hexanedithiol (HDT), trimethylolpropane tris(3-mercaptopropionate) (TPTM) and pentaerythritol tetrakis(3-mercaptopropionate) (PTM), respectively, in the presence of porogenic solvents ( n -propanol and PEG 200) and a catalyst (dimethylphenylphosphine, DMPP). The obtained Monoliths possessed high thermal and chemical stabilities. Besides, they all exhibited high column efficiencies and excellent separation abilities in capillary liquid chromatography (cLC). The highest column efficiency could reach ca. 195,000 N/m for butylbenzene on the Monolith prepared with POSS-MA and TPTM (Monolith POSS-TPTM) in reversed-phase (RP) mode at 0.64 mm/s. Good chromatographic performance were all achieved in the separations of polycyclic aromatic hydrocarbons (PAHs), phenols, anilines, EPA 610 as well as bovine serum albumin (BSA) digest. The high column efficiencies in the range of 51,400–117,000 N/m (achieved on the Monolith POSS-PTM in RP mode) convincingly demonstrated the high separation abilities of these thiol-methacrylate based hybrid Monoliths. All the results demonstrated the feasibility of the phosphines catalyzed thiol-methacrylate Michael addition click reaction in fabrication of Monolithic columns with high efficiency for cLC applications.
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chromatographic assessment of two hybrid Monoliths prepared via epoxy amine ring opening polymerization and methacrylate based free radical polymerization using methacrylate epoxy cyclosiloxane as functional monomer
Journal of Chromatography A, 2014Co-Authors: Guang Huang, Junjie Ou, Hongwei Wang, Jing DongAbstract:Abstract Two kinds of hybrid Monolithic columns were prepared by using methacrylate epoxy cyclosiloxane (epoxy-MA) as functional monomer, containing three epoxy moieties and one methacrylate group. One column was in situ fabricated by ring-opening polymerization of epoxy-MA and 1,10-diaminodecane (DAD) using a porogenic system consisting of isopropanol (IPA), H2O and ethanol at 65 °C for 12 h. The other was prepared by free radical polymerization of epoxy-MA and ethylene dimethacrylate (EDMA) using 1-propanol and 1,4-butanediol as the porogenic solvents at 60 °C for 12 h. Two hybrid Monoliths were investigated on the morphology and chromatographic assessment. Although two kinds of Monolithic columns were prepared with epoxy-MA, their morphologies looked rather different. It could be found that the epoxy-MA–DAD Monolith possessed higher column efficiencies (25,000–34,000 plates/m) for the separation of alkylbenzenes than the epoxy-MA–EDMA Monolith (12,000–13,000 plates/m) in reversed-phase nano-liquid chromatography (nano-LC). Depending on the remaining epoxy or methacrylate groups on the surface of two pristine Monoliths, the epoxy-MA–EDMA Monolith could be easily modified with 1-octadecylamine (ODA) via ring-opening reaction, while the epoxy-MA–DAD Monolith could be modified with stearyl methacrylate (SMA) via free radical reaction. The chromatographic performance for the separation of alkylbenzenes on SMA-modified epoxy-MA–DAD Monolith was remarkably improved (42,000-54,000 plates/m) when compared with that on pristine epoxy-MA–DAD Monolith, while it was not obviously enhanced on ODA-modified epoxy-MA–EDMA Monolith when compared with that on pristine epoxy-MA–EDMA Monolith. The enhancement of the column efficiency of epoxy-MA–DAD Monolith after modification might be ascribed to the decreased mass-transfer resistence. The two kinds of hybrid Monoliths were also applied for separations of six phenols and seven basic compounds in nano-LC.
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facile preparation of a stable and functionalizable hybrid Monolith via ring opening polymerization for capillary liquid chromatography
Journal of Chromatography A, 2013Co-Authors: Junjie Ou, Shouwan Tang, Zhenbin Zhang, Jing DongAbstract:Abstract An organic–inorganic hybrid Monolith was prepared by a single-step ring-opening polymerization of octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS) with poly(ethylenimine) (PEI). The obtained hybrid Monoliths possessed high ordered 3D skeletal microstructure with dual retention mechanism that exhibits reversed-phase (RP) mechanism under polar mobile phase and hydrophilic-interaction liquid chromatography (HILIC) retention mechanism under less polar mobile phase. The high column efficiencies of 110,000 N/m can be achieved for separation of alkylbenzenes in capillary reversed-phase liquid chromatography (cLC). Due to the robust property of hybrid Monolith and the rich primary and secondary amino groups on its surface, the resulting hybrid Monolith was easily modified with γ-gluconolactone and physically coated with cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), respectively. The former was successfully applied for HILIC separation of neutral, basic and acidic polar compounds as well as small peptides, and the latter for enantioseparation of racemates in cLC. The high column efficiencies were achieved in all of those separations. These results demonstrated that the hybrid Monolith (POSS–PEI) possessed high stability and good surface tailorbility, potentially being applied for other research fields
Ziad El Rassi - One of the best experts on this subject based on the ideXlab platform.
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organic Monoliths for hydrophilic interaction electrochromatography chromatography and immunoaffinity chromatography
Electrophoresis, 2012Co-Authors: Dilani N Gunasena, Ziad El RassiAbstract:This article is aimed at providing a review of the progress made over the past decade in the preparation of polar Monoliths for hydrophilic interaction LC (HILIC)/capillary electrochromatography (HI-CEC) and in the design of immuno-Monoliths for immunoaffinity chromatography that are based on some of the polar Monolith precursors used in HILIC/HI-CEC. In addition, this review article discusses some of the applications of polar Monoliths by HILIC and HI-CEC, and the applications of immuno-Monoliths. This article is by no means an exhaustive review of the literature; it is rather a survey of the recent progress made in the field with 83 references published in the past decade on the topics of HILIC and immunoaffinity chromatography Monoliths.
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Organic Monoliths for hydrophilic interaction electrochromatography/chromatography and immunoaffinity chromatography.
Electrophoresis, 2011Co-Authors: Dilani N Gunasena, Ziad El RassiAbstract:This article is aimed at providing a review of the progress made over the past decade in the preparation of polar Monoliths for hydrophilic interaction LC (HILIC)/capillary electrochromatography (HI-CEC) and in the design of immuno-Monoliths for immunoaffinity chromatography that are based on some of the polar Monolith precursors used in HILIC/HI-CEC. In addition, this review article discusses some of the applications of polar Monoliths by HILIC and HI-CEC, and the applications of immuno-Monoliths. This article is by no means an exhaustive review of the literature; it is rather a survey of the recent progress made in the field with 83 references published in the past decade on the topics of HILIC and immunoaffinity chromatography Monoliths.
