• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2737-2742
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• 2011

Ring-opening metathesis polymerization (ROMP) of an ethyl-substituted tetracyclododecene (8-ethyltetracyclo[$4.4.0.1^{2,5}.1^{7,10}$] dodec-3-ene, Et-TCD) was carried out in the presence of a ternary catalyst system consisting of $WCl_6$, triisobutyl aluminium (iso$Bu_3Al$), and ethanol. The optimal molar ratio of Et-TCD/$WCl_3$/iso-$Bu_3Al$/ethanol was found as 500/1/3/2 at which the yield of ring-opened polymer was 100%. 1-Hexene was shown to be an effective molecular weight controlling agent for ROMP reaction of Et-TCD. The hydrogenation of the ring opened polymer (p-Et-TCD) was conducted successfully using Pd(5 wt %)/${\gamma}$-$Al_2O_3$ at $80^{\circ}C$ for 1 h. Chemical structures of p-Et-TCD and its hydrogenated product($H_2$-p-Et-TCD) were characterized using 2D NMR techniques ($^1H-^1H$ COSY and $^1H-^{13}C$ HSQC). The changes of physical properties such as thermal stability, glass transition temperature and light transmittance after the hydrogenation were also investigated using TGA, DSC, and UV.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.103-111
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• 2018

A plasma-catalytic combined process was used as an attempt to improve the conversion efficiency of nitrogen oxides ($NO_x$) over a wide temperature range ($150{\sim}500^{\circ}C$) to cope with the exhaust gas whose temperature varies greatly. Since the catalytic $NO_x$ reduction is effective at high temperatures where the activity of the catalyst itself is high, the $NO_x$ reduction was carried out without plasma generation in the high temperature region. On the other hand, in the low temperature region, the plasma was created in the catalyst bed to make up for the decreased catalytic activity, thereby increasing the $NO_x$ conversion efficiency. Effects of the types of catalysts, the reaction temperature, the concentration of the reducing agent (n-heptane), and the energy density on $NO_x$ conversion efficiency were examined. As a result of comparative analysis of various catalysts, the catalytic $NO_x$ conversion efficiency in the high temperature region was the highest in the case of the $Ag-Zn/{\gamma}-Al_2O_3$ catalyst of more than 90%. In the low temperature region, $NO_x$ was hardly removed by the hydrocarbon selective reduction process, but when the plasma was generated in the catalyst bed, the $NO_x$ conversion sharply increased to about 90%. The $NO_x$ conversion can be maintained high at temperatures of $150{\sim}500^{\circ}C$ by the combination of plasma in accordance with the temperature change of the exhaust gas.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.20-28
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• 2015

This work investigated the size and shape effect of ${\gamma}$-alumina-supported metal oxides on the hydrocarbon selective catalytic reduction of nitrogen oxides. Several metal oxides including Ag, Cu and Ru were used as the catalysts, and n-heptane as the reducing agent. For the Ag/${\gamma}$-alumina catalyst, the $NO_x$ reduction efficiency in the range of $250{\sim}400^{\circ}C$ increased as the size of Ag decreased (20 nm>50 nm>80 nm). The shape effect of metal oxides on the $NO_x$ reduction was examined with spherical- and wire-shape nanoparticles. Under identical condition, higher catalytic activity for $NO_x$ reduction was observed with Ag and Cu wires than with the spheres, while spherical- and wire-shape Ru exhibited similar $NO_x$ reduction efficiency to each other. Among the metal oxides examined, the best catalytic activity for $NO_x$ reduction was obtained with Ag wire, showing almost complete $NO_x$ removal at a temperature of $300^{\circ}C$. For Cu and Ru catalysts, considerable amount of NO was oxidized to $NO_2$, rather than reduced to $N_2$, leading to lower $NO_x$ reduction efficiency.