• Title/Summary/Keyword: Alcohol oxidation

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Benzyl Alcohol Oxidation over H5PMo10V2O40 Catalyst Chemically Immobilized on Sulfur-containing Mesoporous Carbon (황이 포함된 중형기공성 탄소에 화학적으로 고정화된 H5PMo10V2O40 촉매 상에서 Benzyl Alcohol 산화반응)

  • Gim, Min Yeong;Kang, Tae Hun;Choi, Jung Ho;Song, In Kyu
    • Korean Chemical Engineering Research
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    • v.54 no.3
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    • pp.419-424
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    • 2016
  • $H_5PMo_{10}V_2O_{40}$ ($PMo_{10}V_2$) catalyst chemically immobilized on sulfur-containing mesoporous carbon (S-MC) was prepared, and it was applied to the benzyl alcohol oxidation reaction. S-MC was synthesized by a templating method using SBA-15 and p-toluenesulfonic acid as a templating agent and a carbon precursor, respectively. S-MC was then modified to have a positive charge, and thus, to provide sites for the immobilization of $PMo_{10}V_2$. By taking advantage of the overall negative charge of $[PMo_{10}V_2O4_{40}]^{5-}$, $PMo_{10}V_2$ catalyst was immobilized on the S-MC support as a charge matching component. It was revealed that $PMo_{10}V_2$ species were finely and molecularly dispersed on the S-MC via chemical immobilization. In the vapor-phase oxidation of benzyl alcohol, $PMo_{10}V_2$/S-MC catalyst showed higher conversion of benzyl alcohol and higher yield for benzaldehyde and benzoic acid than unsupported $PMo_{10}V_2$ catalyst. The enhanced catalytic performance of $PMo_{10}V_2$/S-MC was due to fine dispersion of $PMo_{10}V_2$ species on the S-MC via chemical immobilization.

Synthesis of Pd/TiO2 Catalyst for Aerobic Benzyl Alcohol Oxidation (호기성 벤질 알코올 산화반응을 위한 팔라듐 이산화티타늄 촉매 개발)

  • Cho, Tae Jun;Yoo, Kye Sang
    • Applied Chemistry for Engineering
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    • v.25 no.3
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    • pp.281-285
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    • 2014
  • $Pd/TiO_2$ particles were prepared by wet impregnation for aerobic benzyl alcohol oxidation. Catalysts were prepared by the impregnation of 10 wt% palladium on $TiO_2$ after calcination at various temperatures. The surface areas of the catalysts were changed with calcination temperature. The catalyst calcined at $300^{\circ}C$ possessed the highest surface areas. Catalytic activity of the prepared samples was examined for aerobic benzyl alcohol oxidation. Among the samples, $Pd/TiO_2$ calcined at $300^{\circ}C$ showed the highest catalytic activity. Moreover, the catalysts with various Pd concentrations from 5 wt% to 15 wt% were prepared to investigate an optimum catalyst. 10 wt% $Pd/TiO_2$ was the most active in this reaction due to its higher surface areas and metal dispersion.

Observation on the Ignition Delay Time of Cool and Thermal Flame of n-heptane/alcohol Blended Fuel at Low Temperature Combustion Regime (저온연소조건에서 n-heptane/alcohol 혼합연료의 냉염과 열염에 대한 착화지연 관찰)

  • Song, Jaehyeok;Kang, Kijoong;Ryu, Seunghyup;Choi, Gyungmin;Kim, Duckjool
    • Journal of the Korean Society of Combustion
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    • v.18 no.4
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    • pp.12-20
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    • 2013
  • The ignition delay time is an important factor to understand the combustion characteristics of internal combustion engine. In this study, ignition delay times of cool and thermal flame were observed separately in homogeneous charge compression ignition(HCCI) engine. This study presents numerical investigation of ignition delay time of n-heptane and alcohol(ethanol and n-butanol) binary fuel. The $O_2$ concentration in the mixture was set 9-10% to simulate high exhaust gas recirculation(EGR) rate condition. The numerical study on the ignition delay time was performed using CHEMKIN codes with various blending ratios and EGR rates. The results revealed that the ignition delay time increased with increasing the alcohol fraction in the mixture due to a decrease of oxidation of n-heptane at the low temperature. From the numerical analysis, ethanol needed more radical and higher temperature than n-butanol for oxidation. In addition, thermal ignition delay time is sharply increasing with decreasing $O_2$ fraction, but cool flame ignition delay time changes negligibly for both binary fuels. Also, in high temperature regime, the ignition delay time showed similar tendency with both blends regardless of blending ratio and EGR rate.

Synthesis of Pd-Ag on Charcoal Catalyst for Aerobic Benzyl Alcohol Oxidation Using [Hmim][PF6] ([Hmim][PF6]를 사용한 벤질 알코올의 호기성 산화반응용 팔라듐-은 차콜 촉매 제조)

  • Choo, Yunjun;Yoo, Kye Sang
    • Applied Chemistry for Engineering
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    • v.25 no.4
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    • pp.425-429
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    • 2014
  • Pd on charcoal particles were prepared by wet impregnation to develop commercial catalyst for aerobic benzyl alcohol oxidation. Especially, one of room temperature ionic liquids, [Hmim][$PF_6$], was used as an effective solvent in the synthesis to improve the metal dispersion of the catalysts. Among the Pd/Charcoal with various Pd concentrations, 7.5 wt% catalyst showed the higher catalytic activity and stability. Moreover, Ag was used as a promoter with various ratios in catalyst preparation. Under identical reaction conditions, the catalyst with 9 : 1 of Pd and Ag weight ratios was most active due to higher metal dispersion.

Purification and Characterization of a Cyclohexanol Dehydrogenase from Rhodococcus sp. TK6

  • Kim, Tae-Kang;Choi, Jun-Ho;Rhee, In-Koo
    • Journal of Microbiology and Biotechnology
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    • v.12 no.1
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    • pp.39-45
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    • 2002
  • Activity staining on the native polyacrylamide gel electrophoresis (PAGE) of a cell-free extract of Rhodococcus sp. TK6, grown in media containing alcohols as the carbon source, revealed at least seven isozyme bands, which were identified as alcohol dehydrogenases that oxidize cyclohexanol to cyclohexanone. Among the alcohol dehydrogenases, cyclohexanol dehydrogenase II (CDH II), which is the major enzyme involved in the oxidation of cyclohexanol, was purified to homogeneity. The molecular mass of the CDH II was determined to be 60 kDa by gel filtration, while the molecular mass of each subunit was estimated to be 28 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The CDH II was unstable in acidic and basic pHs, and rapidly inactivated at temperatures above $40^{\circ}C$ . The CDH II activity was enhanced by the addition of divalent metal ions, like $Ba^2+\;and\;Mg^{2+}$. The purified enzyme catalyzed the oxidation of a broad range of alcohols, including cyclohexanol, trans-cyclohexane-1,2-diol, trans-cyclopentane-l,2-diol, cyclopentanol, and hexane-1,2-diol. The $K_m$ values of the CDH II for cyclohexanol, trans-cyclohexane-l,2-diol, cyclopentanol, trans-cyclopentane-l,2-diol, and hexane-l,2-diol were 1.7, 2.8, 14.2, 13.7, and 13.5 mM, respectively. The CDH II would appear to be a major alcohol dehydrogenase for the oxidation of cyclohexanol. The N-terminal sequence of the CDH II was determined to be TVAHVTGAARGIGRA. Furthermore, based on a comparison of the determined sequence with other short chain alcohol dehydrogenases, the purified CDH II was suggested to be a new enzyme.

Comparison of the Characteristics of Alcohol-Oxidase by the Various Forms (여러 가지 형태에 따른 Alcohol-Oxidase의 특성 비교)

  • 이명숙
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.22 no.6
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    • pp.797-802
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    • 1993
  • The properties of the alcohol-oxidase from yeasts assimilating of methanol(Hansenula polymorpha CBS 4732, Pichia pastoris CBS 2612 and Candida boidinii CBS 8106) as free(cellules, purified enzymes) and immobilized forms(immobilized cellules, immobilized enzymes) were investigated. Immobilization enhanced the activity and stability of alcohol-oxidase to a certain degree. The optimum temperature of the immobilized alcohol-oxidase was lower than those of the free forms. The pH / activi쇼 profiles of alcohol-oxidase did not change by immobilization, but changed by the microorganisms. When the immobilized cellules were stocked at 4$^{\circ}C$ in 10mM potassium phosphate buffer(pH 7.5 or 8.0), alcohol-oxidase was more stable than those were stocked in potassium phosphate buffer containing 0.65M sucrose. The immobilization modifies the conditions of oxidation on the various substrates. alcohol-oxidase in immobilized forms showed some with higher Km value for methanol than that in free ones.

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