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Khan M.K.,Sungkyunkwan University | Sarkar B.,Sungkyunkwan University | Zeb H.,SKKU Advanced Institute of Nano Technology SAINT | Yi M.,SK Innovation | And 3 more authors.
Fuel | Year: 2017

An environmentally-benign supercritical fluid route is developed to demulsify and treat highly intractable petroleum emulsions containing hazardous acidic compounds, heavy fractions, heteroatoms, and metallic impurities without using external catalysts and molecular hydrogen. The produced synthetic crude oil exhibits asphaltene-free fractions with low amounts of impurities, which could be suitable for use in current petroleum refineries. The degree of reductions of asphaltenes and non-distillate fraction are 98.5% and 94.0%, respectively. The deacidification tendency of supercritical methanol results in 90.2% reduction of total acid number. Ni, Ca, and N are removed below detection limits (0.1 ppm for Ni/Ca and 0.01 wt% for N). V and S are reduced with efficiency of 85.0% and 33.6%, respectively. © 2017 Elsevier Ltd


Nugroho A.,Korea Institute of Science and Technology | Nugroho A.,Korean University of Science and Technology | Kim S.J.,Korea Institute of Science and Technology | Chang W.,Korea Institute of Science and Technology | And 3 more authors.
Journal of Power Sources | Year: 2013

A facile, template-free route using supercritical methanol for the preparation of hierarchical mesoporous Li4Ti5O12 spinel microspheres in a very short reaction time is introduced. Nanosized, primary Li4Ti5O12 particles (5e10 nm) are loosely aggregated and form micron-sized, secondary mesoporous spheres (0.2 e2.0 mm) with a pore size of 2e10 nm. Subsequent calcination of the as-synthesized Li4Ti5O12 at a low temperature of 600 C results in excellent long-term cyclability and high rate performance. The discharge capacity after 400 cycles at 1 C is 134.9 mAh g1 (77.6% of the initial discharge capacity), and the discharge capacity at 10 C is 108.5 mAh g1. The formation mechanism of hierarchical mesoporous microspheres in supercritical methanol is discussed. Copyright © 2013 Published by Elsevier B.V. All rights reserved.


Kim S.K.,Korea Institute of Science and Technology | Han J.Y.,Korea Institute of Science and Technology | Hong S.-A.,Korea Institute of Science and Technology | Lee Y.-W.,Seoul National University | And 2 more authors.
Fuel | Year: 2013

Waste cooking oil (WCO) was purified by supercritical carbon dioxide (scCO2) extraction and catalytic hydrodeoxygenation of fresh soybean oil, WCO and scCO2-purified oil were studied for the synthesis of diesel-like hydrocarbons. The chemical compositions of the scCO 2-purified oils were very similar to those of fresh oil. Hydrotreating of WCO over the Pd and Ni catalysts showed lower conversions when compared to the NiMo and CoMo catalysts. The hydrotreating of scCO 2-purified oil using a Pd/Al2O3 catalyst resulted in 85.7% conversion, which is comparable to the 91.0% conversion from fresh oil whereas only 41.8% of WCO was converted under identical conditions. Hydrotreating of the scCO2-purified oil with other catalysts including Ni/SiO2-Al2O3, CoMo/Al 2O3 and NiMo/Al2O3 resulted in similar conversions in the range 84.4-92.9% compared to that from fresh oil. The scCO2-purification was effective for removing the various impurities in WCO, that were responsible for the detrimental effects on catalytic activity especially for the Pd and Ni catalysts. The origin of catalyst deactivation caused by the impurities in WCO is discussed. © 2013 Published by Elsevier Ltd. All rights reserved.


Kim S.K.,Korea Institute of Science and Technology | Brand S.,Korea Institute of Science and Technology | Brand S.,Korean University of Science and Technology | Lee H.-S.,Korea Institute of Science and Technology | And 3 more authors.
Chemical Engineering Journal | Year: 2013

The effects of varying reaction parameters on the hydrotreatment of soybean oil using Ni and CoMoS. x catalysts were investigated. The reactions were carried out in both batch and continuous reactors, at reaction temperatures of 300-440. °C, and hydrogen pressures of 2.5-15.0. MPa. The effects on hydrotreating conversion, gasoline/jet/diesel selectivity, and the degree of oxygen removal were investigated, to find optimum hydrotreatment conditions using both types of catalysts. Analyses of liquid composition, using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) and GC-flame ionization detection (FID), revealed that decarboxylation, decarbonylation, and hydrodeoxygenation reactions occurred competitively, and that each reaction pathway had different optimal conditions, as expected from the thermodynamic characteristics. The differences in the hydrotreatment reaction, liquid product compositions, and dominant reaction pathways between the batch and continuous reactions are also discussed. © 2013.


Susanti R.F.,Korea Institute of Science and Technology | Susanti R.F.,Parahyangan Catholic University | Han Y.S.,Korea Institute of Science and Technology | Kim J.,Sungkyunkwan University | And 3 more authors.
Journal of Membrane Science | Year: 2013

Highly stable, uniform and ultrathin hydrophilic polymer coatings on the surface as well as in the pores of a PVDF microfiltration (MF) membrane are obtained by coating a hydrophilic monomer in liquid carbon dioxide (l-CO2) followed by subsequent crosslinking reaction. Polyethylene glycol diacrylate (PEGDA, Mn ~258g/mol) is used as the l-CO2 soluble hydrophilic monomer source and azobisisobutyronitrile (AIBN) was used as a radical initiator. The extremely low surface tension and the low viscosity of l-CO2 result in ultrathin and uniform PEG coatings on the hydrophobic polyvinylidene fluoride (PVDF) microfiltration membrane. The chemical composition, morphology, and the depth profiles of the PEG-coated membranes are characterized in detail using X-ray photoelectron spectroscopy, scanning electron microscopy, electron probe microanalysis and energy dispersive X-ray microanalysis. Long-term permeation flux test using a bovine serum albumin solution shows that the 1.0wt% PEGDA-coated membrane using l-CO2 exhibits 1.34 times larger BSA solution flux than that of the uncoated PVDF membrane, and 1.3 times larger flux than that of a commercial hydrophilic membrane. Fouling resistance estimation shows that the 1wt% PEGDA-coated membrane exhibits ~30% lower internal fouling resistance than the pristine membrane, and ~24% lower internal fouling resistance than the commercial hydrophilic membrane. © 2013.


Permana A.D.C.,Korea Institute of Science and Technology | Nugroho A.,Korea Institute of Science and Technology | Chung K.Y.,Korea Institute of Science and Technology | Chang W.,Korea Institute of Science and Technology | And 2 more authors.
Chemical Engineering Journal | Year: 2014

Hierarchically porous anatase titanium oxide (TiO2) microspheres were synthesized using a green supercritical methanol route over a very short reaction time of 15min without using templates or surfactants. Primary nano-sized particles with diameters of 20-55nm with organic coverage on the surface were loosely aggregated and formed secondary micron-sized particles 1.0-2.5μm in diameter, creating a porous structure with average pores 9-15nm in diameter. When the as-synthesized microspheres were calcined under a Ar/5% H2 condition, carbonization of the organic groups formed an ultrathin and uniform carbon layer on the nano-sized primary particles with a thickness of 0.5-1nm and reduced some of the Ti4+ to Ti3+. Both the hierarchically porous structure and the conductive layer coating had positive effects by increasing Li ion storage capacity. The prepared TiO2 microspheres exhibited a high reversible discharge capacity of 212.3mAhg-1 at 0.1C, a high-rate performance of 77.9mAhg-1 at 8C, and an excellent capacity retention of >97% at the end of 100 cycles at 1.0C, whereas TiO2 nanoparticles without porous structure and surface modification exhibited lower discharge capacities of 161.8mAhg-1 at 0.1C and 5.2mAhg-1 at 8C, and poorer capacity retention of 26%. The considerable improvement in the electrochemical performance was attributed to the nano-sized TiO2 primary particles, porous structure, and carbon coating and Ti3+ incorporation. © 2013.


Kim Y.,SKKU Advanced Institute of Nano Technology SAINT | Kim Y.,ChangSung Co. | Lee B.,ChangSung Co. | Yang S.,ChangSung Co. | And 3 more authors.
Current Applied Physics | Year: 2012

We have synthesized nano-sized copper hydroxide powder and copper (II) neodecanoate complex that can be decomposed to form copper metal films. Copper conductive ink was then prepared by mixing the powder and complex with a binder in terpineol. The lowest resistivity of 12.5 μΩ cm and 5B level of adhesion strength were obtained with 5% addition of epoxy resin as a binder. The copper ink was then applied to fabricate a loop-type RFID antenna tag and the performance of the antenna was compared with that of conventional copper-etched and silver-paste antenna. The fabricated RFID antenna showed comparable performance to the conventional RFID antenna. © 2011 Elsevier B.V. All rights reserved.


Nugroho A.,Korea Institute of Science and Technology | Chung K.Y.,Korea Institute of Science and Technology | Kim J.,Sungkyunkwan University | Kim J.,SKKU Advanced Institute of Nano Technology SAINT
Journal of Physical Chemistry C | Year: 2014

Hierarchically mesoporous Li4Ti5O12 (LTO) microspheres with a conductive layer coating are considered one of most promising structures to enhance high-rate performance as well as to retain high volumetric energy density. Herein, hierarchically mesoporous LTO microspheres with carbon coating are synthesized through a simple, supercritical alcohol route. The influence of varying synthesis conditions including concentration, solvent, reaction time, and calcination on the physicochemical and electrochemical properties of the LTO microspheres is carefully examined. Mesoporous LTO are synthesized at a short reaction time of 15 min in supercritical alcohols without using any structure-directing chemicals or templates. The use of supercritical methanol (scMeOH) results in a higher degree of surface modification, which retards the crystal growth more effectively when compared to supercritical ethanol (scEtOH) and supercritical isopropanol (scIPA). During heat treatment under a 5% H2/Ar condition, carbonization of the organic groups attached to the surface of LTO effectively restricts particle growth and reduces the surface Ti4+ to Ti 3+. At rapid charge-discharge rates of >8 C, or at long cycles of >50, the discharge capacities of the carbon-coated LTO are ordered scMeOH > scEtOH > scIPA. The higher degree of surface modification from scMeOH results in LTO with higher carbon content, higher Ti3+ content, larger BET surface area, smaller average pore size, and larger porosity when compared to scEtOH and scIPA, which resulted in better electrochemical performance. The formation mechanism of the unique, hierarchically mesoporous structure in the supercritical alcohols is also discussed. © 2013 American Chemical Society.


Kim S.K.,Korea Institute of Science and Technology | Han J.Y.,Korea Institute of Science and Technology | Lee H.-S.,Korea Institute of Science and Technology | Yum T.,Korea Institute of Science and Technology | And 3 more authors.
Applied Energy | Year: 2014

This study describes an efficient one-step method for the comprehensive analysis of the composition of renewable diesel produced directly from a natural triglyceride, including evaluation of its content of partially deoxygenated species. Previous approaches have been capable of only limited, less detailed hydrocarbon analysis because of their poor ability to separate the middle distillates. Moreover, the complexity and the variety of partially deoxygenated reaction intermediates in a typical renewable green diesel, including alcohols, acids, esters, aldehydes, and ketones, have led to difficulties in analyzing the exact composition and in understanding the reaction pathway. Herein, we propose a novel four-dimensional gas chromatography approach combined with time-of-flight mass spectrometry (GC×GC-TOFMS) that will help us gain a fundamental understanding of the reaction pathways that arise when different catalysts and reaction conditions are used. This information could further help in developing deoxygenation catalysts and processes that are more efficient. Based on the GC×GC-TOFMS analysis, different deoxygenation reaction pathways were proposed to be dominant over various catalysts including Pd, Ni, CoMoSx, and NiMoSx under different reaction conditions. © 2013.


Nugroho A.,Korea Institute of Science and Technology | Kim J.,Sungkyunkwan University | Kim J.,SKKU Advanced Institute of Nano Technology SAINT
Journal of Industrial and Engineering Chemistry | Year: 2014

The effects of KOH on the supercritical hydrothermal synthesis of cobalt oxide and manganese oxide particles are investigated using a continuous-flow reactor. Significant changes in morphology, particle size, and oxidation state are observed by adding KOH. The spinel Co3O4 phase is transformed to a rocksalt CoO phase and the pyrolusite MnO2 phase is transformed to a hausmannite Mn3O4 phase in the presence of 0.5M KOH. The average particle size of the metal oxides decreased with an addition of KOH. The OH- ions of KOH may act as a reducing agent as well as a supersaturation enhancing agent under supercritical water conditions. © 2014 Published by Elsevier B.V.

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