• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.325-334
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• 2018

Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru-Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru-Ni bimetallic nanohybrids with $Ru-NiO_x$ (x = 1, 5, and 10 wt%) are prepared by impregnating Ru and Ni salts precursors with $TiO_2$ used as support material. Ru-Ni bimetallic nanohybrids (represented as $5Ru-5NiO/TiO_2$) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. ($374h^{-1}$). In contrast, monometallic $Ru/TiO_2$ catalyst shows poor performance with ($TOF=251h^{-1}$). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic $Ru-NiO/TiO_2$ catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. $Ru-NiO/TiO_2$ efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at $120^{\circ}C$ and 55 bar of hydrogen ($H_2$) pressure. Moreover, $Ru-NiO/TiO_2$ catalyst could also be easily recovered and reused up to four runs without notable change in original activity.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1210-1215
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• 1999

Optimum conditions of the hydrogenation of PNA to pure PPD were determined in a three-phase slurry reactor with suspended Pd/C catalyst particles. Minimization of mass transfer resistances at the interfaces of both gas-liquid and liquid-catalyst particles and control of overall reaction rate on catalyst surface leaded to decrease the hydrogen starvation on reaction active sites and to reduce the side reactions during hydrogenation. The optimum temperature, pressure, and catalysst concentration were confirmed to be in the range of $60^{\circ}C$, 60~70 psig, and 1~2 g-cat/L, respectively. Reaction rate was zero order with respect to the concentration of PNA and 1st order with respect to the pressure of hydrogen(P). Overall rate expression of the reaction was $R_A=6.44{\times}10^6{\cdot}H{\cdot}P{\cdot}m{\cdot}$exp(-4659/T) where H is constant, m is concentration of catalyst, and T is temperature.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1317-1324
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• 2009

Asymmetric transfer hydrogenation of α-functionalized arylketones has been studied. The chiral Rh-catalyst effectively performed in transfer hydrogenation of $\alpha$-mesyloxyketones with an azeotropic mixture of formic acid/triethylamine to produce optically active 1-arylethandiols with excellent enantioselectivity.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.191.2-191.2
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• 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.

• Bulletin of the Korean Chemical Society
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• v.31 no.3
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• pp.635-638
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• 2010

As a new strategy for the optimization of a chiral catalyst, the catalytic activity of the host-guest complexes of chiral bisphosphine bearing imidazolidinone was investigated in Rh-catalyzed asymmetric hydrogenation of enamide. Marginal enhancement in enantioselectivity was observed and the nature of interaction between host-guest was experimentally elucidated.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.993-998
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• 1999

The concurrent production of methanol and dimethyl ether from carbon dioxide hydrogenation has been studied under various reaction conditions. First, the methanol synthesis was compared with the concurrent production method. For the methanol synthesis, the ternary mixed oxide catalyst (CuO/ZnO/Al2O3) was used and for the coproduction of methanol and dimethyl ether, silica-alumina was mixed with the methanol synthesis catalyst to be a hybrid catalyst. The results show that the co-production provides much higher per-pass yield than methanol synthesis even at very short contact time. The effects of temperature, contact time, pressure and catalyst hybrid ratio on the product yields and selectivities were also determined in the co-production.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.504-512
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• 1999

The high-quality carbon nanofibers were prepared by chemical vapor deposition of gas mixtures of CO-H2 and C3H8-H2 over Fe-Cu and Ni-Cu bimetallic catalysts. The yield and structure of carbon nanofiber produced were altered by the change of catalyst composition and reaction temperature. The high yields were obtained around 500$^{\circ}C$ with e-Cu catalyst and around 700-750$^{\circ}C$ with Ni-Cu catalyst and the relatively higher yields were obtained with the bimetallic catalyst containing 50-90% of Ni and Fe respectively in comparison with the pure metals. The carbon nanofibers produced over the Fe-Cu catalyst at around 500$^{\circ}C$ with the maximum yields had the highest surface ares of 160-200 m2/g around 650$^{\circ}C$ which was slightly lower than the temperature for maximum yields. In order to examine the characteristics of carbon nanofibers as catalyst support Ni and Co metals were supporte on the carbon nanofibers and CO hydrogenation reaction was performed with the catalysts. The particle size distribution of Ni and Co supported over the carbon nanofibers were 6-15 nm and the CO hydrogenation reaction rate with the carbon-nanofiber supported catalysts was much higher than that over the other supports.

• Applied Chemistry for Engineering
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• v.2 no.1
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• pp.47-55
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• 1991

Regeneration of carbon-deposited Ni catalyst used for hydrogenation reaction was studied. Deposited carbon was removed by oxidation with various concentrations of oxygen. Activity of the catalysts was tested on aniline hydrogenation as a model reaction. When a carbon-deposited catalyst was treated under oxygen atmosphere, the specific surface area of the catalyst increased and then decreased with the increase of treatment temperature. The treatment temperature which gives maximum specific surface area increased with the decrease of oxygen concentration. Pore size of the support was decreased and sintering of nickel particles was more significant with the increase of oxygen concentration. The catalyst treated under 5 % oxygen concentration recovered its catalytic activity up to 90 % of the initial value, but the treatment under 20 % oxygen concentration gave no significant increase of the catalytic activity. Catalytic activity increased with treatment time when the catalyst was treated under 5 % oxygen concentration, but nearly constant after 1 hour.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1931-1932
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• 2009

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1289-1292
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• 2005