• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1945-1948
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• 2012

Rhodamine B (RhB) and rhodamine 6G (Rh6G) were employed as catalysts for the synthesis of cyclic carbonate from carbon dioxide and epoxide. It turned out that the catalytic activity of Rh6G was nearly 29 times higher than that of RhB at 1 atm pressure, $90^{\circ}C$. Furthermore, the catalytic efficiency of RhB and Rh6G was greatly enhanced with triethylamine as co-catalyst. Under the optimized conditions, the best isolated yield (93%) of cyclic carbonate was achieved without organic solvent and metal component.

• Clean Technology
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• v.23 no.1
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• pp.104-112
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• 2017

Hydrogen production via steam reforming of liquefaction liquid from marine algae over hydrothermal liquefaction was carried out at 873 ~ 1073 K with a commercial catalyst and Ni based $K_2Ti_xO_y$ added catalysts. Liquefaction liquid obtained by hydrothermal liquefaction (503 K, 2 h) was used as a reactant and comparison studies for catalytic activity over different catalysts (FCR-4-02, $Ni/K_2Ti_xO_y-Al_2O_3$, $Ni/K_2Ti_xO_y-SiO_2$, $Ni/K_2Ti_xO_y-ZrO_2/CeO_2$ and Ni/$K_2Ti_xO_y$-MgO), reaction temperature were performed. Experimental results showed Ni/$K_2Ti_xO_y$ based catalysts ($Ni/K_2Ti_xO_y-Al_2O_3$, $Ni/K_2Ti_xO_y-SiO_2$, Ni/$K_2Ti_xO_y-ZrO_2$/ $CeO_2$ and Ni/$K_2Ti_xO_y$-MgO) have a higher activity than commercial catalyst (FCR-4-02) and In particular, a product composition was different depending on support materials. An acidic support ($Al_2O_3$) and a basic support (MgO) led to a higher selectivity for CO while a neutral support ($SiO_2$) and a reducing support ($ZrO_2/CeO_2$) resulted in a higher $CO_2$ selectivity due to water gas shift reaction.

• Polymer(Korea)
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• v.24 no.4
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• pp.437-444
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• 2000

Propylene polymerizations were carried out by using rac-Et(Ind)$_2$ZrCl$_2$ (Zirconocene catalyst) and a commercial third generation Ziegler-Natta catalyst in a semibatch reactor. From the polymerization reactions, the optimum reaction conditions and the physical properties of polymers produced from each catalyst system were investigated. The optimum reaction temperatures of rac-Et(Ind)$_2$ZrCl$_2$ and Ziegler-Natta catalyst were 5$0^{\circ}C$, 4$0^{\circ}C$, respectively. On the basis of the results for the produced polymer particle size distributions and the catalytic activities of polymerization reaction, the reaction temperature should be considered as an important factor for the successful polymerization reactions. Especially, the polymer was conglomerated in the higher reaction temperature. It was found that there was an upper limitation to co-catalyst concentration. Reaction rates and polymer yields rather decreased with increasing the concentration of to-catalyst, i.e., MAO and TEAl affected only polymerization activities, but the PEEB in Ziegler-Natta catalyst system affected isotactic indexes of produced polymer as well as activities. Based on these observations, the production yield seems to exhibit a first order lineal relationship to the partial pressure of monomer.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.430-439
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• 2000

$In_2O_3$-based thin film sensor with 500-600 nm thick was fabricated for the detection of CO gas by rf magnetron sputtering. In order to improve both sensitivity to CO gas and selectivity to hydrogen gas containing -CH, ultra-thin transition metal Co catalyst was sputtered over $In_2O_3$ thin film and annealed at $500^{\circ}C$. Sensitivity to CO was maximum at the thickness of Co 2.1 nm and $300^{\circ}C$, and that to $C_3H_8$ was at the thickness of Co 1.4 nm and $350-400^{\circ}C$. From the x-ray photoelectron spectroscopy (XPS) result, ultra-thin Co was existed into CoO covered with $Co_2O_3$ on $In_2O_3$ particles, and thus p-n junction of $In_2O_3(n-type)$-CoO(p-type) was thought to be formed. In this p-n junction type sensors, sensing mechanism with reducing gases can be explained by the variation of depletion layer thickness formed in the interface.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.158.2-158.2
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• 2011

DME is acronym of dimethyl ether, which is spotlighted as an ideal fuel to produce hydrogen due to its high hydrogen/carbon ratio, high energy density and easiness to carry. In this research, we calculated thermodynamic hydrogen (or syngas) yield from DME autothermal reforming and compared to other fuels. The reforming efficiency was about 80% above $700^{\circ}C$. Lower OCR has higher reforming efficiency but, it requires additional heat supply since the reactions are endothermic. SCR has no significant effect on the reforming efficiency. The optimized condition is $700^{\circ}C$, SCR 1.5, OCR 0.45 without additional heat supply. Comparing to other commercial gaseous fuels (methane and propane), DME has higher selectivity of $H_2O$ and $CO_2$ than the others due to the oxygen atom in the molecule. To apply DME autothermal reforming to real system, a proper catalyst is required. Therefore, it is performed the experiment comparing various novel metal catalysts based on CGO. Experiments were performed at calculated condition. The composition of product was measured and reforming efficiency was calculated. The catalysts have similar efficiency at high temperature(${\sim}800^{\circ}C$) but, CGO-Ru has the highest efficiency at low temperature ($600^{\circ}C$).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.622-626
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• 2010

Cu doped $SnO_2$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and annealed at $500^{\circ}C$ in air, respectively. Structural properties of $SnO_2$ by X-ray diffraction showed (110), (101) and (211) dominant tetragonal phase. The effects of catalyst Cu in $SnO_2$-based gas sensors were investigated. Sensitivity of $SnO_2$:Cu sensors to 2,000 ppm $CO_2$ gas and 50 ppm $H_2S$ gas was investigated for various Cu concentration. The highest sensitivity to $CO_2$ gas and $H_2S$ gas of Cu doped $SnO_2$ gas sensors was observed at the 8 wt% and 12 wt% Cu concentration, respectively. The improved sensitivity in the Cu doped $SnO_2$ gas sensors was explained by decrease of electron depletion region in Cu and $SnO_2$ junction, and increase of reactive oxygen and surface area in the $SnO_2$.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.87-94
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• 2017

In this study, a catalyst based on $Pt/Al_2O_3$ supported on Mg was prepared by a wet impregnation method to investigate the $CH_4-SCR$ reaction characteristics of various alumina supports. Alumina supported on $Pt/Al_2O_3$ catalyst was converted to an $Al_2O_3$ composite, and when Mg was added, oxygen species of the active metal Pt were controlled due to electrophobic characteristics. Oxygen-controlled Pt used as a reducing agent inhibited the oxidation of $CH_4$ to $CO_2$. The addition of Mg also promoted the adsorption of NO species and the conversion of NO to $NO_2$ due to the NOx storage property on the catalyst surface.

• Resources Recycling
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• v.30 no.3
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• pp.47-54
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• 2021

Palladium present in colloidal-type plated spent catalyst solution that is used in electroless plating process has not been recovered but discharged as wastewater so far. Recyclig of paladium in colloidal-type plated spent catalyst solution is achieved with this study. This study presents the estimation of resource consumption and GHG emissions during the recycling and disposal of palladium in the plated spent catalyst solution using life cycle assessment. The reduction of resources and GHG are also estimated. Based on the palladium amount of 1 kg during disposal, the GHG emission amount was estimated to be 9.67E+03 kgCO₂eq., and the amount of resource consumption was 3.94E+01 kgSb-eq. However, GHG emission was 1.96E+03 kgCO₂eq., and the amount of resource consumption was 1.54E+01 kgSb-eq. during recycling. Considering the major substances affecting GHG emissions and amount of resource consumption, CO₂ was found to significantly affect GHG emissions, accounting for 91.42% in disposal and 98.37% in recycling. The major substance affecting the amount of resource consumption was hard coal, which accounted for 40.63% in disposal and 60.73% in recycling. Upon recycling 1 kg palladium, 8,967.17 kgCO₂eq. of greenhouse gas emission was reduced, while the resource consumption was reduced to 10.10 kg Sb-eq. In addition, the direct palladium resource reduction rate due to palladium recycling was 50%.

• 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.10 no.3
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• pp.313-320
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• 2019

In this study, cobalt diselenide ($CoSe_2$) and the composites ($CoSe_2@RGO$) of $CoSe_2$ and reduced graphene oxide (RGO) were synthesized by a facile hydrothermal reaction using cobalt ions and selenide source with or without graphene oxide (GO). The formation of $CoSe_2@RGO$ composites was identified by analysis with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). Electrochemical analyses demonstrated that the $CoSe_2@RGO$ composites have excellent catalytic activity for the reduction of $I_3{^-}$, possibly indicating a synergetic effect of $CoSe_2$ and RGO. As a consequence, the $CoSe_2@RGO$ composites were applied as a counter electrode in DSSC for the reduction of redox couple electrolyte, and exhibiting the comparable power conversion efficiency (7.01%) to the rare metal platinum (Pt) based photovoltaic device (6.77%).