• Composites Research
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• v.29 no.4
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• pp.216-222
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• 2016

Ring-opening metathesis polymerization of p-dicyclopentadiene (DCPD) can be performed using the tungsten type catalyst. This reaction usually progresses in nitrogen condition, because the catalysts are extremely sensitive in air condition. To solve this problem, DCPD resin with tungsten (W) was cured using hot press after stirring of DCPD A and B liquid in air condition. Mechanical properties of DCPD were improved by reducing microvoid occurrence successfully by using hot press method. It might be because hot press could provide sufficient press on DCPD specimen. Addition of catalyst was not effective for the curing of resin in a short time. During polymerization, pressure and temperature had a great influence on the mechanical properties of DCPD.

• Composites Research
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• v.29 no.5
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• pp.282-287
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• 2016

p-DCPD (poly dicyclopentadiene) is the resin that the versatile mechanical properties can be changeable via the control of inner monomer and catalysts. In this work, to improve the strength of composites, surface treated MGF (milled glass fiber) was used as an reinforcement in p-DCPD by molybdenum (Mo) catalyst matrix. The optimum concentration of surface treatment was obtained and the cohesion of MGF themselves increased with concentration. In case of 0.2 wt% silane concentration, the maximized mechanical properties of MGF/p-DCPD composite exhibited because of minimized MGF cohesion. When butyl silane showing minimizing cohesion was used as the optimized alkyl length, high tensile and flexure strength exhibited due to the steric hindrance effect among MGFs. Mechanical and their fractured surfaces of MGF/p-DCPD composites was compared for 4 different chemical functional groups. Norbornene functional groups containing similar chemical structure to DCPD matrix exhibited higher interfacial adhesion between MGFs and DCPD matrix.

• Composites Research
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• v.32 no.6
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• pp.355-359
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• 2019

The high efficient water splitting system should involve the reduction of high overpotential value, which was enhanced by the electrocatalytic reaction efficiency of catalysts, during the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) reaction, respectively. Among them, transition metal-based compounds (oxides, sulfides, phosphides, and nitrides) are attracting attention as catalyst materials to replace noble metals that are currently commercially available. Herein, we synthesized optimal monodisperse Co₃[Co(CN)₆]₂ PBAs by FESEM, and confirmed crystallinity by XRD and FT-IR, and thermal behavior of PBAs via TG-DTA. Also, we synthesized monodispersed Co₃O₄ nanocubes by calcination of Co₃[Co(CN)₆]₂ PBAs, confirmed the crystallinity by XRD, and proceeded OER measurement. Finally, the synthesized Co₃O₄ nanocubes showed a low overpotential of 312 mV at a current density of 10 mA·cm^-2 with a low Tafel plot (96.6 mV·dec^-1).

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.62-66
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• 2018

Styrenated phenol alkoxylates (SP-A) were prepared from styrenated phenol (SP) and ethylene oxide (EO) under a homogeneous base catalyst. However, to use EO that is difficult to handle, a high-pressure reaction device capable of controlling the reaction process should be used. Additionally, when a homogeneous base catalyst is used, a neutralization process is required to remove residual bases after the reaction, and it is also difficult to separate the catalyst and the product. Therefore, in this study, we report the results of SP-A prepared from the reaction of SP and EC using only heterogeneous base catalysts. The heterogeneous base catalyst was obtained by supporting KOH on $La_2O_3$ and calcintion. Using EC instead of EO, it was possible to produce SP-A under the atmospheric rather than high-pressure reaction condition. Average molecular weights of synthesized SP-A varied greatly depending on reaction conditions. The average molecular weight of SP-A prepared using the $KOH/La_2O_3$ catalyst could be controlled arbitrarily by controlling the reaction temperature and added catalyst and EC amounts.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.22-27
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• 2018

In this study, the effect of physical properties of $Pt/TiO_2$ on $NH_3$-selective catalytic oxidation (SCO) reaction at $200{\sim}350^{\circ}C$ was investigated. CO-chemisoption and BET analysis were carried out to verify physical properties of $Pt/TiO_2$. By characterizing physical properties of $Pt/TiO_2$ with respect to the Pt loading, the metal dispersion degree decreased as a function of the Pt loading amount. Also, the catalyst having a higher metal dispersion showed an excellent conversion efficiency of $NH_3$ to $N_2$. Since the specific surface area of the support affects the metal dispersion, $Pt/TiO_2$ catalysts were prepared using $TiO_2$ with different physical properties. As a result, it was confirmed that the catalyst having a wide specific surface area exhibited a excellent conversion of $NH_3$ to $N_2$.

• Clean Technology
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• v.13 no.4
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• pp.293-299
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• 2007

Direct coating of catalyst layer on the $Nafion^{(R)}$ membrane has been optimized in the process of fabrication of membrane electrode assembly (MEA) to enhance the performance of direct methanol fuel cell (DMFC). In this method, the contact resistance at the interface of the catalyst layer and the membrane was found to be low. The effect of catalyst loading, thickness of membrane and the gas diffusion layer (GDL) with or without the presence of micro-porous layer (MPL) on the performance of the MEA was also investigated. The MEA fabricated by the above-mentioned method exhibited a performance of $147\;mW/cm^2$ and $100\;mW/cm^2$ at $80^{\circ}C$ and $60^{\circ}C$, respectively, with the catalysts loading of $4\;mg/cm^2$.

• Clean Technology
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• v.20 no.3
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• pp.212-217
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• 2014

In order to regenerate the sulfidated desulfurization sorbent, oxygen is used as the oxidant agent on the regeneration process. The small amount of oxygen un-reacted in regeneration process is flowed into direct sulfur recovery process. However, the reactivity for $SO_2$ reduction can be deteriorated with the un-reacted oxygen by various reasons. In this study, the deactivation effects of un-reacted oxygen contained in the off-gas of regeneration process flowed into direct sulfur recovery process of hot gas desulfurization system were investigated. Sn-Zr based catalysts were used as the catalyst for $SO_2$ reduction. The contents of $SO_2$ and $O_2$ contained in the regenerator off-gas used as the reactants were fixed to 5.0 vol% and 4.0 vol%, respectively. The catalytic activity tests with a Sn-Zr based catalyst were for $SO_2$ reduction performed at $300-450^{\circ}C$ and 1-20 atm. The un-reacted oxygen oxidized the elemental sulfur produced by $SO_2$ catalytic reduction and the conversion of $SO_2$ was reduced due to the production of $SO_2$. However, the temperature for the oxidation of elemental sulfur increased with increasing pressure in the catalytic reactor. Therefore, it was concluded that the decrease of reactivity at high pressure is occurred by catalytic deactivation, which is the re-oxidation of lattice oxygen vacancy in Sn-Zr based catalyst with the un-reacted oxygen on the catalysis by redox mechanism. Meanwhile the un-reacted oxygen oxidized CO supplied as the reducing agent and the temperature in the catalyst packed bed also increased due to the combustion of CO. It was concluded that the rapidly increasing temperature in the packed bed can induce the catalytic deactivation such as the sintering of active components.

• Clean Technology
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• v.20 no.3
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• pp.269-276
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• 2014

This study was aimed to develop catalytic system for the dry-based reduction of oxidized mercury ($Hg^{2+}$) to elemental mercury ($Hg^0$) which is one of the most important components comprising mercury continuous emission monitoring system (Hg-CEMS). Based on the standard potential in oxidation-reduction reaction, transition metals including Fe, Cu, Ni and Co were selected as possible candidates for catalyst proceeding spontaneous reduction of $Hg^{2+}$ into $Hg^0$. These transition metal catalysts revealed high activity for reduction of $Hg^{2+}$ into $Hg^0$ in the absence of oxygen in reactant gases. However, their activities were greatly decreased in the presence of oxygen, which was attributed to the transformation of transition metals by oxygen to the corresponding transition metal oxides with less catalytic activity for the reduction of oxidized mercury. Hydrogen supplied to the reactant gases significantly enhanced $Hg^{2+}$ reduction activity even in the presence of oxygen. It might be due to occurrence of combustion reaction between $H_2$ and $O_2$ causing the consumption of $O_2$ at such high reaction temperature at which oxidized mercury reduction reaction took place. Because the system showed high activity for $Hg^{2+}$ reduction to $Hg^0$, which was compatible to that of wet-chemistry technology using $SnCl_2$ solution, the catalytic reduction system of Fe catalyst with the supply of $H_2$ could be employed as a commercial system for the reduction of oxidized mercury to elemental mercury.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.619-625
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• 2017

In this study, the formation of hydroxyl radical and decomposition characteristics of bisphenol A (BPA) was investigated by quantifying hydrogen peroxide formed as a reaction by-product during the formation stage of hydroperoxyl radical. The direct oxidation reaction by ozone only decomposed BPA just like the Criegee mechanism under the condition where radical chain reactions did not occur. Non-selective oxidation reactions occurred under the conditions of pH 6.5 and 9.5 where radical chain reactions do occur, confirming indirectly the formation of hydroxyl radical. The decomposition efficiency of BPA by the added catalysts appeared in the order of $O_3$/PAC ${\geq}$ $O_3/H_2O_2$ > $O_3$/high pH > $O_3$ alone. 0.03~0.08 mM of hydrogen peroxide were continuously measured during the oxidation reactions of ozone/catalyst processes. In the case of $O_3$/high pH process, BPA was completely decomposed in 50 min of the oxidation reaction, but reaction intermediates formed by oxidation reaction were not oxidized sufficiently with 29% of the removal ratio for total organic carbon (TOC, selective oxidation reaction). In the case of $O_3/H_2O_2$ and $O_3$/PAC processes, BPA was completely decomposed in 40 min of the oxidation reaction, and reaction intermediates formed by the oxidation reaction were oxidized with 57% and 66% of removal ratios for TOC, respectively (non-selective oxidation reactions).

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.432-439
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• 2018

Metal catalysts such as Fe, Co, Mn, and Pd supported on the activated carbon (AC) were prepared to improve functional groups for the chemical adsorption and catalytic ozonation. Following ascending orders of the phenol decomposition rate, dissolved ozone decomposition ratio and TOC (total organic carbon) removal from experimental results of advanced oxidation process (AOP) were observed: Fe-AC < AC < Co-AC < Mn-AC < Pd-AC. BET analysis results showed that the physical properties of the metal impregnated activated carbon had no effect on the catalytic ozonation, and the catalytic effect was dependent on the kind of impregnated metal. The ratio of the formed concentration of OH radical to that of ozone (RCT) was measured by using the decomposition outcome of p-chlorobenzoic acid, a probe compound that reacts rapidly with OH radical but slowly with ozone. The measured values of RCT were $5.48{\times}10^{-9}$ and $1.47{\times}10^{-8}$ for the ozone alone and activated carbon processes, respectively, and $2.13{\times}10^{-9}$, $1.51{\times}10^{-8}$, $4.77{\times}10^{-8}$, and $5.58{\times}10^{-8}$ for Fe-AC, Co-AC, Mn-AC, and Pd-AC processes, respectively.