• Transactions of the Korean hydrogen and new energy society
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• v.25 no.3
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• pp.247-254
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• 2014

The synthesis of Fischer-Tropsch oil is the catalytic hydrogenation of CO to give a range of products, which can be used for the production of high-quality diesel fuel, gasoline and linear chemicals. Our cobalt based catalyst was prepared Co/alumina, silica and titania by the incipient wet impregnation of the nitrates of cobalt and promoter with supports. Cobalt catalysts was calcined at $350^{\circ}C$ before being loaded into the FT reactors. After the reduction of catalyst has been carried out under $450^{\circ}C$ for 24hrs, FT reaction of the catalyst has been carried out at GHSV of 4,000/hr under $200^{\circ}C$ and 20atm. From these test results, we have obtained the results as following ; in case of 12wt% Co-supported $Al_2O_3$, $SiO_2$ and $TiO_2$ catalysts, maximum activities of the catalysts were appeared at the promoters of Mn, Mo and Ce respectively. The activity of 12wt% $Co/Al_2O_3$ added a Mn promoter was about 3 times as high as that of 12wt% $Co/Al_2O_3$ catalyst without promoters. When it has been the experiment at the range of reaction temperature of $200{\sim}220^{\circ}C$ and GHSV of 1,546~5,000/hr, the results have shown generally increasing the activities with the increase of reaction temperature and GHSV.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.29.1-29.1
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• 2011

The selective catalytic reduction (SCR) of $MnO_x$ with $NH_3$ is an effective method for the removal of $MnO_x$ from stationary system. The typical catalyst for this method is $V_2O_5-WO_3(MoO_3)/TiO_2$, caused by the high activity and stability. However, This catalyst is active within $300{\sim}400^{\circ}C$ and occurs the pore plugging from the deposition of ammonium sulfate salts on the catalysts surface. It needs to locate the SCR unit after the desulfurizer and electrostatic precipitator without reheating of the flue gas as well as deposition of dust on the catalyst. The manganese oxides supported on titania catalysts have attracted interest because of its high SCR activity at low temperature. The catalytic activity of $MnO_x/TiO_2$ SCR catalyst with different manganese precursors have investigated for low-temperature SCR in terms of structural, morphological, and physico-chemical analyses. The $MnO_x/TiO_2$ were prepared from three different precursors such as manganese nitrate, manganese acetate (II), and manganese acetate (III) by the sol-gel method and then it calcinated at $500^{\circ}C$ for 2 hr. The structural analysis was carried out to identify the phase transition and the change intensity of catalytic activity by various manganese precursors was analyzed by FT-IR and Raman spectroscopy. These different precursors also led to various surface Mn concentrations indicated by SEM. The Mn acetate (III) tends to be more suppressive the crystalline phase (rutile), and it has not only smaller particle size, but also better distributed than the others. It was confirmed that the catalytic activity of MA (III)-$MnO_x/TiO_2$ was the highest among them.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.522-526
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• 2009

The catalytic oxidation of 1,2-dichloribenzene (1,2-DCB) and simultaneous catalytic reduction of nitrogen oxides over the single catalyst has been investigated over various metals (Ru, Mn, Co and Fe) supported on $Al_2O_3$ and $CeO_{2}$. The activity of the different catalysts for catalytic oxidation of 1,2-dichloribenzene depended on the used metal, Ru/Co/$Al_2O_3$, Mn-Fe/CeO2 and Cr/$Al_2O_3$ (commercial catalysts) being the most actives ones. In the catalytic oxidation of chlorobenzene (CB), Ru/Co/$Al_2O_3$ is better than Pt-Pd/$Al_2O_3$, which is the well-known catalyst good for VOC oxidation. Furthermore, it has a good durability on the deactivation by $Cl_2$ and sulfur. For nitrogen oxides (NOx) removal, NOx conversion was 70% at $260^{\circ}C$.

• Analytical Science and Technology
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• v.23 no.4
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• pp.383-388
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• 2010

Catalytic dissociation reaction was studied in order to transform waste plastics to oil by using noble metal supported catalysts. XRD, SEM, and GC/MSD analysis were performed to find the crystalline structure and shape, and product distribution. Generally, dissociation reaction occurs at low temperature compared to pyrolysis. Dissociation reaction has advantage of gasoline yield with respect to pyrolysis which products mainly $C_1\simC_4$. The result of dissociation reaction, gasoline was obtained much as a product. $C_5\simC_{11}$ compounds were produced as a gasoline product on Pt-zeolite among noble metal catalysts at $340^{\circ}C$. The conversion of dissociation reaction of waste plastics on the prepared catalyst was above 70% over $340^{\circ}C$.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.295-304
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• 1994

$Mo-V-O/SnO_2$(VM/Sn) and $SnO_2/Mo-V-O$(Sn/VM) catalysts have been prepared and characterized by XRD, BET, SEM and TPD of ammonia. The catalytic reaction of acrolein oxidation with these catalysts, in a continuous-flow fixed-bed reactor, showed that they had higher conversion of acrolein and higher yield of acrylic acid than those of Mo-V-O itself. The origin of the observed synergy studied by TPD, TPR and TPO is explained by the cooperation of $SnO_2$ and Mo-V-O at their interfaces where electrons flow from Mo-V-O phase to $SnO_2$ and $SnO_2$ produces spill-over oxygens, which, by being transported onto the surface of Mo-V-O, reoxidize the partially reduced active sites.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.555-564
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• 2016

In recent years, methanol has attracted much attention since it can be cleanly manufactured by the combined use of atmospheric $CO_2$ recycling and water splitting via renewable energy. For the concept of "methanol economy", an active methanol synthesis catalyst should be prepared in a sophisticated manner rather than by empirical optimization approach. Even though Cu/ZnO-based catalysts prepared by coprecipitation are well known and have been extensively investigated even for a century, fundamental understanding on the precipitation chemistry and catalyst nanostructure has recently been achieved due to complexity of the necessary preparation steps such as precipitation, ageing, filtering, washing, drying, calcination and reduction. Herein we review the recent reports regarding the effects of various synthesis variables in each step on the physicochemical properties of materials in precursor, calcined and reduced states. The relationship between these characteristics and the catalytic performance will also be discussed because many variables in each step strongly influence the final catalytic activity, called "chemical memory". All discussion focuses on how to prepare a highly active Cu/ZnO-based catalyst for methanol synthesis. Furthermore, the preparation strategy we deliver here would be utilized for designing other coprecipitation-derived supported metal or metal oxide catalysts.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.410-415
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• 1996

It is well known that the heavy water separation process using hydrogen isotope exchange reaction over the platinum catalyst is the most efficient. In this study, the Pt/silicalite catalysts were prepared and characterized by hydrogen adsorption in order to develop the hydrophobic platinum catalyst for hydrogen isotope exchange reaction. Silicalite was synthesized as support material and it was verified that silicalite is more hydrophobic than activated carbon and ZSM-5. Also the platinum was loaded on silicalite by conventional impregnation and ion-exchange method respectively. The platinum dispersion of Pt/silicalite catalysts was measured through hydrogen adsorption experiment. The dispersion is very low in the catalyst prepared by the impregnation method while it is very high with limited platinum content in the catalyst prepared by the ion-exchange method.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.155-170
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• 2003

$Cu-Ce/{\gamma}-Al_2O_3$ based catalysts were prepared and tested for selective oxidation of CO in a $H_2$-rich stream(1% CO, 1% $O_2$, 60% $H_2$, $N_2$ as balance). The effects of Cu loading and weight ratio(=Cu/(Cu+Ce)) upon both activity and selectivity were investigated upon the change in temperatures, It was also examined how the activity and selectivity of catalysts were varied with the presence of $CO_2$ and $H_2O$ in the reactant feed. Among the various Cu-Ce catalysts with different catalytic metal composition, Cu-Ce(4 : 16 wf%) /${\gamma}-Al_2O_3$ catalyst showed the highest activity(>$T_{99}$) and selectivities(50-80%) under wide range of temperatures($175-220^{\circ}C$). However, in the Cu-Ce(4 : 16 wt%)/ ${\gamma}-Al_2O_3$, the presence of $CO_2$ and $H_2O$ in the reactant feed decreased the activity and the maximum activity(>$T_{99}$) in terms of reaction temperature moved by about $25^{\circ}C$ toward higher temperature, the $T_{>99}$ window was seen between $210-230^{\circ}C$ (selectivity 50-75%). From $CO_2-/H_2O-TPD$, it can be concluded that the main cause for the decrease in catalytic activity may be attributed to the blockage of the active sites by competitive adsorption of water vapor and $CO_2$ with the reactant at low temperatures.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Ceramist
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• v.23 no.2
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• pp.200-210
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• 2020

Supported catalysts are at the heart of manufacturing essential chemical, agricultural and pharmaceutical products. While the longevity of such systems is critically hinged on the durability of metal nanoparticles, the conventional deposition/dispersion techniques are difficult to enhance the stability of the metal nanoparticles due to the lack of control over the interaction between metal-support. Regarding this matter, ex-solution has begun to be recognized as one of the most promising methodologies to develop thermally and chemically robust nanoparticles. By dissolving desired catalysts as a cation form into a parent oxide, fine and uniformly distributed metal nano-catalysts can be subsequently grown in situ under reductive heat treatment, which is referred to ex-solution. Over the several years, ex-solved analog has resulted in tremendous progress in the chemical-electrochemical applications due to the exceptional robustness coupled with ease synthesis. Herein, we describe the ex-solution process in detail which therein introducing the unique characteristics of ex-solved particles that distinguish them from conventionally dispersed nanoparticles. We then go through the history of science regarding the ex-solution phenomena and summarize several major research achievements which embrace the ex-solved nanoparticles to markedly promote the catalytic performances. In conclusion, we address the remaining challenges and the future perspectives of this rapidly growing field.