• 제목/요약/키워드: CO Hydrogenation

검색결과 79건 처리시간 0.024초

Hydrogenation of trans-Cinnamaldehyde with Hydrido-Carbonyl Osmium(II) Complexes of Chelating Phosphine Ligands

  • 정민교;허성;이원용;전무진
    • Bulletin of the Korean Chemical Society
    • /
    • 제18권8호
    • /
    • pp.806-810
    • /
    • 1997
  • A series of new hydridocarbonyl osmium(Ⅱ) complexes, OsHCl(CO)(PPh3)(L-L)[L-L=Ph2P(CH2)nPPh2 (n=1 (1), 2 (2), 3 (3), cis-Ph2PCH=CHPPh2 (4), and Fe(η5-C5H4PPh2)2 (5)] has been synthesized from OsHCl(CO)(PPh3)3 and chelating diphosphines. These complexes have been characterized by IR, 1H NMR and elemental analysis. The catalytic activities of these complexes both for the transfer hydrogenation of trans-cinnamaldehyde with 2-propanol as the hydrogen donor, and for the selective hydrogenation of trans-cinnamaldehyde with H2, have been examined. Complexes (1)-(5) were shown to have higher selectivities for the transfer hydrogenation of the C=O bond of aldehyde than for the transfer hydrogenation of the C=C bond of aldehyde. The selectivities for the transfer hydrogenation with 2-propanol as well as for the hydrogenation with H2 have been found to decrease in the order 3 > 5 > 2 > 4 > 1. Complex (3) has shown to possess almost 90% of the selectivity to cinnamyl alcohol for transfer hydrogenation. It is also found that there is a correlation between the ν(CO) of each complex and the hydrogenation, of the C=O bond of trans-cinnamaldehyde. Overall, the selectivities with the complexes (1)-(5) are greater for the transfer hydrogenation with 2-propanol than for the hydrogenation with H2.

Adsorption and Thermal Reduction Mechanism of CO2 on ZnO/Cu Model Catalysts

  • Kim, Yeonwoo;Kim, Sehun
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
    • /
    • pp.191.2-191.2
    • /
    • 2014
  • Cu/ZnO/$Al_2O_3$ is widely used methanol synthesis catalyst at elevated pressures P (50 to 100 bar) and temperatures T (473 to 573 K) using $CO_2$, CO, $H_2$ syngas mixture. Although Cu step and planar defects have been regarded as active sites in this catalyst, detailed $CO_2$ hydrogenation procedure has been still unknown and debated as well as initial intermediate. In this study, we investigated the mechanism of $CO_2$ hydrogenation on Cu(111) model surface at P (1 bar) and T (298 to 450 K) using reflection absorption infrared spectroscopy (RAIRS). Two distinct formates by hydrogenation of $CO_2$, on step and on terrace, show different behavior with elevating temperature. The peak intensity of on step formate was continuously decreased above 360 K up to 450K in contrast to the increase of on terrace formate. These phenomena are strong possibilities that the formate is initial intermediate and is desorbed by hydrogenation reaction because thermal desorption temperature of formate (~470 K) is much higher than desorption of on step formate. And the formate production peak of on step site was weakly correlated with CO formation.

  • PDF

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

  • Woo, Jin-Chun;Chin, Chong-Shik
    • Bulletin of the Korean Chemical Society
    • /
    • 제4권4호
    • /
    • pp.169-171
    • /
    • 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 $RhCl(Ph_3P)_2$.

Cataytic Hydrogenation of o-Nitrochlorbenzene to 3,3'-Dichlorobenzidine

  • Shen, Kaihua;Li, Shude;Choi, Dong-Hoon
    • Bulletin of the Korean Chemical Society
    • /
    • 제23권12호
    • /
    • pp.1785-1789
    • /
    • 2002
  • 2,2'-Dichlorohydroazobenzene was prepared by selective hydrogenation of o-nitrochlorobenzene with hydrogen in the presence of 0.8% and 5% Pd/C catalyst. O-Chloroaniline was a minor product in the catalytic hydrogenation of o-nitrochlorobenzene. The effects of base, Pd/C catalyst, and co-catalyst were discussed on catalytic hydrogenation. 2,2'-Dichlorohydroazobenzene, as an intermediate, was rearranged to 3,3'-dichlorobenzidine after reacting with HCl. It was shown that selectivity of catalytic hydrogenation of o-nitro-chlorobenzene is affected strongly by concentration of base, Pd/C catalyst, and co-catalyst. $^1Hand^{13}C$NMR spectroscopy confirmed the chemical structures of 2,2'-dichlorohydrazobenzene and 3,3'-dichlorobenzidine.

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
    • /
    • 제4권4호
    • /
    • pp.180-183
    • /
    • 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.

In Situ-DRIFTS Study of Rh Promoted CuCo/Al2O3 for Ethanol Synthesis via CO Hydrogenation

  • Li, Fang;Ma, Hongfang;Zhang, Haitao;Ying, Weiyong;Fang, Dingye
    • Bulletin of the Korean Chemical Society
    • /
    • 제35권9호
    • /
    • pp.2726-2732
    • /
    • 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.

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

  • 고명선;박일송;박제신
    • 한국분말재료학회지
    • /
    • 제26권4호
    • /
    • pp.290-298
    • /
    • 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.

몰리브덴과 텅스텐 착물을 이용한 카르보닐기의 이온성 수소화 반응 (Ionic Hydrogenation of Carbonyl Groups With Molybdenum and Tungsten Complexes)

  • 송정섭
    • 한국산학기술학회논문지
    • /
    • 제7권4호
    • /
    • pp.715-720
    • /
    • 2006
  • CO와 유사한 분자궤도함수를 갖는 isocyanide 리간드가 포함된$Cp(CO)_{2}(L)MH$ (L = t-butylisocyanide and 2,6-dimethylphenylisocyanide M = Mo and W)를 합성하고, 이 착물과 triflic acid를 사용하여 카르보닐기를 알코올로 전환시키는 실험을 하였다. 또한, 이들 착물을 촉매 전구체로 이용하여 3-pentanone의 수소화 반응을 온화한 조건 ($23^{\circ}C,\;<4.1\;atm H_{2}$)에서 수행하였다. 촉매 활성은 매우 낮았으며, [$Cp(CO)_{2}(ArNC)Mo][BA_{r}^{F}_{4}$]의 경우에 2 turnovers/day의 결과를 나타내었다.

  • PDF

Hydrogenation and Isomerization of Soybean Oil with Perchloratocarbonylbis-(triphenylphosphine) rhodium (Ⅰ)

  • Jeong, Hyun-Mok;Chin, Chong-Shik
    • Bulletin of the Korean Chemical Society
    • /
    • 제5권5호
    • /
    • pp.199-201
    • /
    • 1984
  • It has been found that $Rh(ClO_4)(CO)(P(C_6H_5)_3)_2$ catalyzes the hydrogenation and isomerization of soybean oil at room temperature under the atmospheric pressure of hydrogen. The hydrogenation occurs at the olefinic groups to produce saturated groups leaving the ester groups intact, and the isomerization converts $-CH = CH- CH_2-CH = CH-$ units to conjugated dienes and the dienes separated by more than two $-CH_2-$ groups. The rate of the hydrogenation is faster than that of the isomerization.

Alkylhydridorhodium(Ⅲ) Route for Isomerization and Hydrogenation of Unsaturated Alcohols with Rh(ClO$_4)(CO)(PPh_3)_2$ and [Rh(CO)(PPh$_3)_3]ClO_4$ under Hydrogen

  • Chin, Chong-Shik;Park, Jeong-Han;Kim, Choon-Gil
    • Bulletin of the Korean Chemical Society
    • /
    • 제10권4호
    • /
    • pp.360-362
    • /
    • 1989
  • Catalytic isomerization of unsaturated alcohols to the corresponding carbonyl compounds with$Rh(ClO_4)(CO)(PPh_3)_2\;(1)\;and\;[Rh(CO)(PPh_3)_3]ClO_4$ (2) is faster under hydrogen (where hydrogenation also occurs to give saturated alcohols) than under nitrogen. The isomerization under hydrogen seems to occur through an alkylhydridorhodium(III) complex which also undergoes reductive elimination to give hydrogenation products, saturated alcohols. The isomerization under hydrogen is faster with 2 than with 1, which is understood by acceleration of the last step, enol formation by $PPh_3$ dissociated from 2 and present in the reaction mixture when 2 is used as catalyst. Relative rates of the isomerization observed for different unsaturated alcohols are interpreted by steric effects of substituted groups and numbers of hydrogens to be abstracted by the rhodium of the intermediate, alkylhydridorhodium(III) to undergo the reductive elimination to give enol which is then rapidly converted into a carbonyl compound. It has been observed that the hydrogenation is relatively significant when reactions occur slowly whereas the isomerization is predominant when reactions proceed rapidly.