• Title/Summary/Keyword: hydrogenation

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Hydrogenation of ZnO:Al Thin Films Using Hot Filament

  • An, Il-Sin;Kim, Ok-Kyung;Lee, Chang-Hyo;Ahn, You-Shin
    • Journal of Korean Vacuum Science & Technology
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    • v.4 no.3
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    • pp.86-90
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    • 2000
  • ZnO : Al films were prepared through the optimization process of aluminum content and substrate temperature in rf-magnetron sputtering. When hydrogenation was performed on these films using a hot filament method, all films showed improvement in conductivity although more conductive film showed less improvement. When the substrate temperature ($T_H$) was varied from $25^{\circ}C\;to\;300^{\circ}C$ during hydrogenation, the resistivity was reduced more at higher $T_H$ (more than 30% at $T_H=300^{\circ}C$) Thus, two methods were developed to suppress the dehydrogenation in ZnO : Al films : (1) capping with amorphous silicon thin film as a diffusion barrier, and (2) cooling during hydrogenation.

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Homogeneous Catalysis (VI). Hydride Route with Chloro Ligand Dissociation for the Hydrogenation of Acrylonitrile with trans-Chlorocarbonylbis(triphenylphosphine)iridium(I)

  • Moon, Chi-Jang;Chin, Chong-Shik
    • Bulletin of the Korean Chemical Society
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    • v.4 no.4
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    • pp.180-183
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    • 1983
  • The reaction of $IrClH_2(CO)(Ph_3P)_2$ ($Ph_3P$=triphenylphosphine) with acrylonitrile (AN) produces a stoichiometric amount of propionitrile (PN) at $100^{\circ}C$ under nitrogen, which suggests that the catalytic hydrogenation of AN to PN with $IrCl(CO)(Ph_3P)_2$ proceeds through the hydride route where the formation of the dihydrido complex, $IrClH_2(CO)(Ph_3P)_2$ is the initial step. The rate of the hydrogenation of AN to PN with $IrCl(CO)(Ph_3P)_2$ is decreased by the presence of excess $Cl^-$ in the reaction system, which suggests that $Cl^-$ is the dissociating ligand in the catalytic cycle. It has been also found that the rate of the hydrogenation increases with inercase both in hydrogen pressure and in concentration of free $Ph_3P$, and with decrease in AN concentration in the reaction system.

Homogeneous Catalysis (IV). Hydrogenation of Acrylonitrile with trans-Chlorocarbonylbis(triphenylphosphine)rhodium(I)

  • Woo, Jin-Chun;Chin, Chong-Shik
    • Bulletin of the Korean Chemical Society
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    • v.4 no.4
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    • pp.169-171
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    • 1983
  • It has been found that the acrylonitrile solution of trans-$RhCl(CO)(Ph_3P)_2$ produces propionitrile catalytically at $90^{\circ}C$ under $P_{H_2}$=3 atm. This catalytic hydrogenation proceeds only for a certain period of time producing ca. 50 moles of propionitrile per mole of the rhodium complex. The hydrogenation with trans-$RhCl(CO)(Ph_3P)_2$ in the presence of formaldehyde is much faster than in the absence of formaldehyde, and continues without a decrease in the rate for a prolonged period of time. It is suggested that the hydrogenation with trans-$RhCl(CO)(Ph_3P)_2$ proceeds through the unsaturated route initiated by the dissociation of CO from trans- $RhCl(CO)(Ph_3P)_2$ to give coordinatively unsaturated $RhCl(Ph_3P)_2$.

Carbon-silica composites supported Pt as catalyst for asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate

  • Mao, Cong;Zhang, Jie;Xiao, Meitian;Liu, Yongjun;Zhang, Xueqin
    • Current Applied Physics
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    • v.18 no.12
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    • pp.1480-1485
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    • 2018
  • Mesoporous carbon-silica composites supported Pt nanoparticle catalysts (Pt/MCS) were firstly applied to the heterogeneous asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutyrate (EOPB). A series of different silica contents were investigated in the fabrication of this mesoporous material. When the volume of added tetraethyl orthosilicate (TEOS) during the preparation of composites is 8 mL, Pt/MCS-8 holds carbon and silica as the main components and possesses relatively strong acidity, mesoporous structures with micropores, appropriate Pt nanoparticle size and high dispersibility showing by XRD, XPS, TPD, $N_2$ sorption and TEM. These properties cause its good catalytic performance in the heterogeneous asymmetric hydrogenation of EOPB with the enantiomeric excess value and conversion up to 85.6% and 97.8%, respectively.

Bimetallic Pd@Ni-mesoporous TiO2 nanocatalyst for highly improved and selective hydrogenation of carbonyl compounds under UV light radiation

  • Bathla, Aadil;Pal, Bonamali
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.486-496
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    • 2018
  • Bimetallic Pd@Ni nanostructure exhibited enhanced co-catalytic activity for the selective hydrogenation of benzaldehyde compare to their monometallic counterparts. Impregnation of these mono/bimetallic nanostructures on mesoporous $TiO_2$ leads to several surface modifications. The bimetallic PNT-3 ($Pd_3@Ni_1/mTiO_2$) exhibited large surface area ($212m^2g^{-1}$), and low recombination rate of the charge carriers ($e^--h^+$). The hydrogenation reaction was analyzed under controlled experiments. It was observed that under UV-light irradiations and saturated hydrogen atmosphere the bimetallic PNT-3 photocatalyst display higher rate constant $k=5.31{\times}10^{-1}h^{-1}$ owing to reduction in the barrier height which leads to efficiently transfer of electron at bimetallic/$mTiO_2$ interface.

Liquid Phase Hydrogenation of Croton Aldehyde with Nickel Catalysts (니켈촉매에 의한 크로톤 알데히드의 액상 수소첨가반응)

  • Lee, Hak Sung;Park, Young Hae;Kim, Yong Sup
    • Applied Chemistry for Engineering
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    • v.5 no.3
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    • pp.509-516
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    • 1994
  • Liquid phase hydrogenation come into use for the removal process of unsaturated hydrocarbon such as croton aldehyde. The croton aldehyde is generated in a very small amount as by-product in the ethanol production, and it is converted into n-butanol through hydrogenation. Liquid phase hydrogenation is low energy consumption process as compared with gas phase hydrogenation. The nickel catalyst is selected with respect to the economic aspect such as durability and cost. The analysis of the conversion were performed by method of the PMT(permangante time) test. The PMT was sharply decreased as the initial concentrations of croton aldehyde in the ethanol solution were increased. The hydrogenation of croton aldehyde to n-butanol was carried out in sequence after the saturation of the carbon-carbon double bond. The formation of both butyraldehyde and n-butanol followed zero order kinetics. Within expermental conditions the PMT gets longer as reaction temperature goes higer and as LHSV becomes slower, while the reaction pressure has almost no relation with PMT.

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The Extraction and Derivatization of Organotins in Water Sample by Gas Chromatograph/Mass Spectrometer (기체크로마토그래프/질량분석기에 의한 물시료 중 Organotin의 추출 및 유도체 반응에 관한 연구)

  • Hong, Jee-Eun;Lee, Kang-Jin;Pyo, Hee Soo;Park, Song-Ja;Lee, Won
    • Analytical Science and Technology
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    • v.13 no.5
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    • pp.636-645
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    • 2000
  • A method is described for the determination of organotins in water samples by GC/MS. Optimized derivatization methods for ethylation and hydrogenation of organotins were surveyed according to various reaction conditions such as time, pH and concentration of reagents. The organotins were extracted with n-hexane in presence of 0.1% tropolone and hydrogenated with sodium borohydride. Extraction recoveries of organotins with hydrogenation were in the range of 61-112%. After ethylation, organotins in water samples were extracted by liquid-liquid extraction (LLE) and solid-phase extraction (SPE). Using LLE, extraction recoveries were in the range of 74-113%. The recoveries ranged from 61-97% in the case of SPE with styrene-divinylbenzene copolymers. Method detection limits of hydrogenated and ethylated organotins ranged from 0.05 to 0.5 ng/ml and from 0.02 to 0.05 ng/ml, respectively.

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The Microstructure and the Mechanical Properties of Sintered TiO2-Co Composite Prepared Via Thermal Hydrogenation Method (열 수소화법에 의해 제조된 TiO2-Co 복합분말 SPS 소결체의 미세구조 및 기계적 성질)

  • Ko, Myeongsun;Park, Ilsong;Park, Jeshin
    • Journal of Powder Materials
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    • v.26 no.4
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    • pp.290-298
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    • 2019
  • $TiO_2$-particles containing Co grains are fabricated via thermal hydrogenation and selective oxidation of TiCo alloy. For comparison, $TiO_2$-Co composite powders are prepared by two kinds of methods which were the mechanical carbonization and oxidation process, and the conventional mixing process. The microstructural characteristics of the prepared composites are analyzed by X-ray diffraction, field-emission scattering electron microscopy, and transmission electron microscopy. In addition, the composite powders are sintered at $800^{\circ}C$ by spark plasma sintering. The flexural strength and fracture toughness of the sintered samples prepared by thermal hydrogenation and mechanical carbonization are found to be higher than those of the samples prepared by the conventional mixing process. Moreover, the microstructures of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes are found to be similar. The difference in the mechanical properties of sintered samples prepared by thermal hydrogenation and mechanical carbonization processes is attributed to the different sizes of metallic Co particles in the samples.

Changes in the Physicochemical Characteristics and Triglyceride Molecular Species of Corn oil during Hydrogenation (수소첨가에 따른 옥수수유의 트리글리세리드 분자종 및 이화학적 특성의 변화)

  • Kim, Hyeon-Wee;Cha, Ik-Soo;Kim, Jin-Ho;Kim, Hyun-Suck;Park, Ki-Moon;Son, Se-Hyung
    • Korean Journal of Food Science and Technology
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    • v.25 no.6
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    • pp.637-642
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    • 1993
  • Changes in the physicochemical characteristics and triglyceride molecular species of corn oil under the following condition of hydrogenation; temperature $180^{\circ}C,\;H_{2}$, pressure $2.0{\pm}0.3bar$, the amount of Ni catalyst 0.048%(Ni/oil by wt.) and agitation speed 300 rpm. The rate of hydrogenation, expressed as the reduction rate of the iodine value with respect to time, is first order and high (K>0.01). When the reduction rate of the iodine value was 39.9%, hydrogenation time was 30 min, 18:1 was highest(77.06%), thereafter that was decreased and 18:0 increased. In the triglyceride composition, OLL, LLL were reduced markedly in 10 min, thereafter reduced slightly. And PLO, PLL, OLO were eliminated in first 30 min. On the other hand, POO, PLS(CN52) and OOO, SLO(CN54) were increased sharply, and then that showed little change. The melting point(MP) of hydrogenated corn oil were $27.8^{\circ}C\;and\;44.1^{\circ}C$ after 20 min and 60 min, respectively. Trans isomer content increased to 46.8% during 40 mins of hydrogenation and then decreased insignificantly. The solid fat content were linearly increased with hydrogenation time. Accordingly, it is confirmed that this condition of hydrogenation was selective, preferential elimination of polyunsaturated fatty acid went stepwise and trans isomer was formed promotedly. These results suggest that fat modification techniques can be used for practical application.

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