• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1320-1322
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• 2008

Phosphomolybdic acid supported on silica gel (PMA-$SiO_2$) is an efficient catalyst for the activation of TMSCN for the facile cyanosilylation of various aldehydes. Cyano transfer from TMSCN to aldehyde proceeds smoothly at rt in presence of 0.8 mol % of PMA-$SiO_2$ leading to a range of cyanosilylether in excellent yield (mostly over 93%) within short reaction time (30 min). The catalyst can be recovered and reused several times without loss of activity.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2149-2155
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• 2012

A metal-free and efficient procedure for the oxidation of alcohols into the corresponding carbonyl compounds has been described using ammonium nitrate in the presence of silica sulfuric acid under mild and heterogeneous conditions. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are among the advantages of this method.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1021-1026
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• 2012

The transient mass transfer in a single droplet system consisting of 1-octanol (continuous phase)/aqueous succinic acid solution (dispersed phase) was investigated in the presence of chemical reaction, which is acid/anion exchange reaction of succinic acid and tri-n-octylamine (TOA). This succinic acid extraction by TOA can be considered to occur at the interface between organic and aqueous phase, that is, heterogeneous reaction system. The basic properties of the system such as viscosity, density, distribution coefficient, terminal velocity of droplet, and diffusion coefficient were measured experimentally or calculated theoretically, and used for theoretical calculation of characteristic parameters of mass transfer later. The effects of succinic acid concentration on the terminal velocity was negligible in the existence of TOA, although the terminal velocity increases with succinic acid concentration in the absence of TOA. On the contrary, the terminal velocity decreases with TOA concentration. While droplets falls through organic phase, the trajectory of droplets is observed to oscillate around its vertical path. A mass trnasfer cell was prepared to monitor the mass transfer behavior in a single droplet and used to measure the mean concentration of succinic acid inside droplet. The results are expressed with dimensionless parameters. Under 50 g/L succinic acid condition, the system with 0.1 mol/kg TOA showed that the molar flux decreases in proportion to the decrease of concentration gradient, while in the case of 0.5 mol/kg TOA Sh increases rapidly with time indicating the molar flux of succinic acid decreases relatively slowly compared to the decrease in concentration gradient.

• Journal of the Korean Chemical Society
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• v.19 no.5
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• pp.381-385
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• 1975

Calcinated alunite powder (surface area 5100 $cm^2/g$) was found to react with well stirred ammonium buffer solution (pH 8.0) following Jander's equation. The rate constants increase with the amount of solid and temperature of reaction system. The energy of activation for the reactions (at $30{\sim}60^{\circ}C$) was 15.7 kcal/mole. The rate-determining step appears to involve ionization of alunite.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1381-1385
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• 2006

Cobalt (cyclam) complex has been successfully immobilized onto SBA-15, and proven to be an active catalyst for the epoxidation of styrene with tert-butyl hydroperoxide as a terminal oxidant. The selectivity for styrene oxide was observed to be up to 66% with 40% styrene conversion after 12h reaction time. The reversible redox cycle between Co(III) and Co(II) couple which was supposed to play key role during the epoxidation reaction was supported by a cyclic voltametry analysis. The textural properties of the catalyst was characterized by XRD, N2 adsorption-desorption, and TEM analysis.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2243-2248
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• 2011

Carbon-based solid acid catalyst was found to be highly efficient, eco-friendly and recyclable heterogeneous catalyst for the multicomponent reaction of dimedone, aromatic aldehydes, and a nitrogen source (ammonium acetate or aromatic amines) under solvent-free conditions, giving rise to 1,8-dioxodecahydroacridines in high yields. The present methodology offers several advantages, such as a simple procedure with an easy work-up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.56-63
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• 2006

In this paper, heat and mass transfer characteristics through experimental and numerical study are extensively investigated in steam reforming reactor under given operating conditions. In order to get simulated data at outlet of the reformer, heterogeneous reactor model is incorporated. As the reaction also takes place in porous media, two medium approach is used to take into account thermally non-equilibrium phenomena between catalyst and bulk gas. From various parametric studies, significance of heat transfer is emphasized in steam reforming reaction.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.108.2-108.2
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• 2011

This presentation shows energy-efficiency of microwave-accelerated esterification of free fatty acid with a heterogeneous catalyst by net microwave power measurement. In the reaction condition of 5wt% sulfated zirconia and 1:20 molar ratio of oil to methanol at $60^{\circ}C$ and atmospheric pressure, more than 90% conversion of the esterification was achieved in 20 minutes by microwave heating, while it took about 130 minutes by conventional heating. Electric energy consumption for the microwave heating in this accelerated esterification was only 67% of estimated minimum heat energy demand because of significantly reduced reaction time.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3289-3294
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• 2013

An efficient method for the preparation of 8-benzylidene-4-phenyl-3,4,5,6,7,8-hexahydro-1H-quinazolin-2-ones/thiones from the reaction of aromatic aldehydes with cyclohexanone and urea or thiourea in the presence of Tetrabutylammonium hexatungstate, $[TBA]_2[W_6O_{19}]$, as an efficient, inexpensive catalyst under thermal and solvent-free conditions has been developed. Good yields, short reaction times, straightforward workup, reusability of the catalyst, and green conditions are the most obvious advantages of this procedure.

• Food Industry And Nutrition
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• v.2 no.1
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• pp.31-41
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• 1997

Stevioside 는 남미 파라과이 원산의 국화와 식물인 Ste-via rebaudiana Bertoni 유래의 천연대체감미료서 식품, 의약품, 주류 산업에 널리 활용되고 있다. 이와 같은 stevio-side 의 구조와 특성, 제조방법, 그리고 사용현황 등을 기술하였으며, 당전이 stevioside의 종류 제조방법을 정리하였다. 본 연구실에서 개발한 생전분을 당공여체로 히용하는 분쇄마찰매체 효소반응계와 팽윤 extrusion 전분을 당공여체로 이용하는 불균일상 효소반응계에서의 stevioside 당전이반응의 특성과 산업적 활용 가능성을 검토하였다. 상기 두 종류의 불균일상 효소반응계는 높은 수율, 반응속도, 낮은 maltooligo 당의 축적, 용이한 당전이 stevioside 의 분리정제 등 기존의 액화 전분을 당공여체로 이용하는 반응계에 비하여 많은 장점이 예상되는 산업적 활용 가능성이 높고 고효율 반응계임을 알 수 있었다. 끝으로 stevioside 감미료의 장래 전망에 관하여 예측하였다.