• Title/Summary/Keyword: Asymmetric division

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Asymmetric Hydrogenation of Ethyl Pyruvate over Bimetallic Rh-Pt/Al2O3 Catalysts Modified with Dihydrocinchonidine (Dihydrocinchonidine으로 개질된 Rh-Pt/Al2O3 이원금속 촉매를 이용한 Ethyl Pyruvate의 비대칭 수소화)

  • Cho, Hong-Baek;Kang, Joon-seok;Park, Yeung-Ho
    • Applied Chemistry for Engineering
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    • v.17 no.4
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    • pp.369-374
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    • 2006

  • $Rh-Pt/Al_{2}O_{3}$ catalysts were used for the first time to study its reaction characteristics in the asymmetric hydrogenation of ethyl pyruvate. The catalysts were prepared either by impregnation of Rh on a commercial $Pt/Al_{2}O_{3}$ or by sequential impregnation of Rh followed by impregnation of Pt on $Al_{2}O_{3}$. Reaction rate and enantiomeric excess (ee%) were compared according to the preparation method, Rh contents, and the reduction temperature of the catalyst. The physical characteristics of the catalysts were analyzed using XRD and TEM. Bimetallic $Rh-Pt/Al_{2}O_{3}$ catalysts showed an improved reaction rate and optical purity (63.6 ee%) with increasing the reduction temperature. The variation of the Rh contents as well as the preparation method elicited a big difference on the reaction rate, while enantiomeric excess (ee%) was lower (56~60%) with all bimetallic catalysts than with monometallic $Pt/Al_{2}O_{3}$ catalyst.

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Asymmetric Price Responses of Industrial Energy Demand in Korea (산업부문 에너지 수요의 비대칭 가격반응)

  • Sukha Shin
    • Environmental and Resource Economics Review
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    • v.32 no.4
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    • pp.267-292
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    • 2023

  • In this paper, we estimate a time series model of energy demand in the industrial sector with an asymmetric response to energy prices. Including the asymmetric response to energy prices in the model strengthens robustness of the cointegration relationship and reduces the variation of the estimated coefficients across the estimating methods. We find that rising energy prices have a larger impact on energy demand than falling energy prices, with the largest impact occurring when energy prices rise to new highs. The estimation results are partially improved when using gross output rather than value added as a measure of production. Using single equation methods to estimate the asymmetric response model, the elasticity of gross output ranged from 1.05 to 1.09 and the elasticity of price-rise ranged from -0.48 to -0.56, which is similar to the results of international studies.

  • https://doi.org/10.15266/KEREA.2023.32.4.267 인용 PDF