• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.190-194
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• 2012

10 wt% Mn supported on various commercial $TiO_2$ catalysts were prepared by wet-impregnation method for the low temperature selective catalytic reduction (SCR) of NO with $NH_3$. A combination of various physico-chemical techniques such as BET, XRD, XPS and TPR were used to characterize these catalysts. MnOx surface densities on MnOx/$TiO_2$ catalyst were related to surface area. As MnOx surface density lowered with high dispersion, the SCR activity for low temperature was increased and the reduction temperature ($MnO_2$ ${\rightarrow}$ $Mn_2O_3$) of surface MnOx was lower. For a high SCR, MnOx could be supported on a high surface area of $TiO_2$ and should be existed a high dispersion of non-crystalline species.

• Clean Technology
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• v.17 no.2
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• pp.166-174
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• 2011

The xAl-yCe oxide catalysts with different mol ratios of Al/(Al+Ce) were prepared by a co-precipitation method and Pt supported on xAl-yCe oxide catalysts were synthesized by an incipient wetness impregnation method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $H_2$/CO-temperature programmed reduction ($H_2$/CO-TPR) to correlate with catalytic activities in co oxidation. Among the catalysts studied here, Pt/1Al-9Ce oxide catalyst showed the highest activity in dry and wet reaction conditions and the catalytic activity showed a typical volcano-shape curve with respect to Al/(Al+Ce) mol ratio. When the presence of 5% water vapor in the feed, the temperature of $T_{50%}$ was shifted ca. $30^{\circ}C$ to lower temperature region than that in dry condition. From CO-TPR, the desorption peak of $CO_2$ on Pt/1Al-9Ce oxide catalyst showed the highest value and well correlated the catalytic performance. It indicates that the Pt/1Al-9Ce oxide catalyst has a large amount of active sites which can be adsorbed by co and easy to supplies the needed oxygen. In addition, the amount of pentacoordinated $Al^{3+}$ sites obtained through $^{27}Al$ NMR analysis is well correlated the catalytic performance.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.328-334
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• 2007

Chemical heat pump system of 2-propanol/acetone/hydrogen is most suitable to the recovery of waste heat of power plant. various types of 5 wt% Pt-alumina catalysts were prepared for 2-propanol dehydrogenation using sol-gel method. The characteristics and the dehydrogenation reaction rate of each catalyst were investigated. Pt-alumina xerogel catalyst has excellent reaction rate and good durability in comparison with the existing alumina supported Pt catalysts. Pt-alumina aerogel catalyst had the highest reaction rate in all prepared catalysts, but sufficient aging time was necessary to maintain its reaction rate. A potential advantage of the aerogel catalyst is the fact that the high temperature heat treatment is not required. Without heat treatment or with low temperature heat treatment, the Pt-alumina aerogel catalyst has excellent reaction rate as well as durability and this gives us the economic advantage. Alumina xerogel supported Pt catalyst prepared by incipient wetness method showed good reaction rate, and had good mechanical strength. Blank alumina xerogel prepared by sol-gel method can be used for the support of metal catalysts.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.891-897
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• 2019

In this study, heteropoly acid PVMo catalysts were supported on activated carbon with various composition of phosphoric acid ($H_3PO_4$), vanadium (V) pentoxide ($V_2O_5$) and molybdenum (VI) trioxide ($MoO_3$). Catalytic performance was examined at $140^{\circ}C$ for 1hour in vapor formaldehyde. XRD and BET analyses were carried with the catalysts before and after the reaction. Formaldehyde conversion was increased with decreasing Mo and $H_3PO_4$ content and increasing $V_2O_5$ content. Acidity of the catalysts was investigated with $NH_3-TPD$. Crystallinity of the catalysts was relatively low, and surface area was decreased after the reaction. In $NH_3-TPD$ result, the ratio of strong acid site corresponding to $NH_3$ desorption between $400^{\circ}C$ and $500^{\circ}C$ was increased by decreasing $MoO_3$ and $H_3PO_4$ content and increasing $V_2O_5$ content. Therefore, it was found that the strong acid site could affect the catalytic reactivity in vapor formaldehyde conversion.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.138-143
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• 2011

Nanosized Pt, Pt-Ru and Pt-$CeO_2$ electrocatalysts supported on acid-treated carbon nanotube (CNT) were synthesized by microwave-assisted heating of polyol process using $H_2Cl_6Pt{\cdot}6H_2O$, $RuCl_3$, $CeCl_3$ precursors, respectively, and were characterized by XRD and TEM. And then the electrochemical activity of methanol oxidation for catalyst/CNT nanocomposite electrodes was investigated. The microwave assisted polyol process produced the nano-sized crystalline catalysts particles on CNT. The size of Pt supported on CNT was 7~12 nm but it decreased to 3~5 nm in which 10wt% sodium acetate was added as a stabilizer during the polyol process. This fine Pt catalyst particles resulted in a higher current density for Pt/CNT electrode. It was also found that 10 nm size of PtRu alloys were formed by polyol process and the onset potential decreased with Ru addition. Cyclic voltammetry analysis revealed that the $Pt_{75}Ru_{25}/CNT$ electrode had the highest electrochemical activity owing to a higher ratio of the forward to reverse anodic peak current. And the chronoamperemetry test showed that $Pt_{75}Ru_{25}$ catalyst had a good catalyst stability. The activity of Pt was also found to be improved with the addition of $CeO_2$.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2726-2732
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• 2014

The promoting effect of rhodium on the structure and activity of the supported Cu-Co based catalysts for CO hydrogenation was investigated in detail. The samples were characterized by DRIFTS, $N_2$-adsorption, XRD, $H_2$-TPR, $H_2$-TPD and XPS. The results indicated that the introduction of rhodium to Cu-Co catalysts resulted in modification of metal dispersion, reducibility and crystal structure. DRIFTS results of CO hydrogenation at reaction condition (P=2 MPa, $T=260^{\circ}C$) indicated the addition of 1 wt % rhodium improved hydrogenation ability of Cu-Co catalysts. The ethanol selectivity and CO conversion were both improved by 1 wt % Rh promoted Cu-Co based catalysts. The alcohol distribution over un-promoted and rhodium promoted Cu-Co based catalysts obeys A-S-F rule and higher chain growth probability was got on rhodium promoted catalyst.

• Journal of Electrochemical Science and Technology
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• v.6 no.3
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• pp.95-105
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• 2015

In the present work, Carbon supported Pt₁₀₀, Pt₈₀Sn₂₀, Pt₈₀Ni₂₀ and Pt₈₀Sn₁₀Ni₁₀ electrocatalysts with different atomic ratios were prepared by ethylene glycol-reduction method to study the electro-oxidation of ethanol in membraneless fuel cell. The electrocatalysts were characterized in terms of structure, morphology and composition by using XRD, TEM and EDX techniques. Transmission electron microscopy measurements revealed a decrease in the mean particle size of the catalysts for the ternary compositions. The electrocatalytic activities of Pt₁₀₀/C, Pt₈₀Sn₂₀/C, Pt₈₀Ni₂₀/C and Pt₈₀Sn₁₀Ni₁₀/C catalysts for ethanol oxidation in an acid medium were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results showed that addition of Ni to Pt/C and Pt-Sn/C catalysts significantly shifted the onset of ethanol and CO oxidations toward lower potentials. The single membraneless ethanol fuel cell performances of the Pt₈₀Sn₁₀Ni₁₀/C, Pt₈₀Sn₂₀/C and Pt₈₀Ni₂₀/C anode catalysts were evaluated at room temperature. Among the catalysts investigated, the power density obtained for Pt₈₀Sn₁₀Ni₁₀/C (37.77 mW/cm² ) catalyst was higher than that of Pt₈₀Sn₂₀/C (22.89 mW/cm² ) and Pt₈₀Ni₂₀/C (16.77 mW/ cm² ), using 1.0 M ethanol + 0.5 M H₂SO₄ as anode feed and 0.1 M sodium percarbonate + 0.5 M H₂SO₄ as cathode feed.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.163-172
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• 2018

In this study, selective catalytic reductions (SCR) of NO commercial catalysts were used to investigate the effect of ammonia gasification from urea solution. The effects of catalytic chemical composition on the reaction temperature and space velocity were studied. $V_2O_5/TiO_2$ catalysts, which are widely used as SCR catalysts for removal of nitrogen oxides, have better ammonia formation compare to $TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The $TiO_2$ catalyst not supporting the active metal was not affected by the space velocity as compared with the catalyst supporting $V_2O_5$ or $WO_3-V_2O_5$. The active metal supported catalysts decreased in the ammonia formation as the space velocity increased.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.24-34
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• 1992

Recent studies dealing with the fundamental understanding and applications of bimetallic catalysts are discussed. Bimetallic catalysts have had a major industrial impact, specifically for the reforming of petroleum naphtha, for the hydrogen reduction of carbon monoxide, and for the three way catalytic converter system. The action of the bimetallic catalysts in these reactions may be interpreted in terms of ensembles, electronic influences and surface structure. Various combinations of metal pairs have been considered in order to evaluate the role played by the added metals. For catalyst selectivity control, the possibility of surface enrichment of one element has been recognised. More generally, the influence of preparative variables on the formation of supported catalysts has been clarified, In particular by temperature programmed reduction (TPR). Information on the structure of bimetallic catalysts has been obtained with chemical probes, such as chemisorption and reaction rate measurement and physical probes, such as extended X-ray absorption fine structure (EXAFS), scanning transmission electron microscopy (STEM) and Xe-NMR.

• Elastomers and Composites
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• v.53 no.3
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• pp.158-167
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• 2018

In this study, in-situ trans-selective polymerization of isoprene was carried out using titanium-based Ziegler-Natta catalysts. The catalysts were prepared by high-energy ball milling. Individually Large-inner-diameter carbon nanotubes (CNTL), and hydroxylated carbon nanotubes (CNTOH), along with magnesium chloride ($MgCl_2$) were used as the carriers for the catalysts. The optimum ball-milling time for preparing the $CNT/MgCl_2/TiCl_4$ Ziegler-Natta catalysts was 4 h. The $CNTOH/MgCl_2/TiCl_4$ catalyst showed a higher efficiency than that of the $CNTL/MgCl_2/TiCl_4$ catalyst, based on the rate of polymerization. The effects of the CNT-filler type on the isoprene polymerization behaviors and polymer properties were investigated. The morphologies of the trans-1,4-polyisoprene (TPI)/CNT and TPI/CNTOH nanocomposites exhibited a tube-like shape, and the CNTL and CNTOH fillers were well dispersed in the TPI matrix. In addition, the thermal stability of TPI significantly increased upon the introduction of a small amount of both CNTL/CNTOH fillers (0.15 wt%), owing to the satisfactory dispersion of the CNTL/CNTOH in the TPI matrix.