• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1508-1512
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• 2013

A simple and efficient synthesis of 2,4,5-trisubstituted imidazoles was achieved via a one-pot three-component cyclocondensation of benzil, aromatic aldehydes, and ammonium acetate in the presence of a catalytic amount of tetrabutylammonium hexatungstate $[TBA]_2[W_6O_{19}]$ as a heterogeneous catalyst under thermal solvent-free conditions. The key features of this methodology are operational simplicity, high yields, short reaction times, and a recyclable catalyst with a very easy work up.

• Environmental Engineering Research
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• 제10권1호
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• pp.31-37
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• 2005

The selective catalytic experiments using both sulfated/sulfur-free titania and V2O5/TiO2 catalysts have been conducted for NO reduction by NH3 in a packed-bed, down-flow reactor. The sulfated and vanadia loaded titania exhibited higher activity for NO removal than the sulfur-free catalysts, where > 90% NO removal was achieved over the sulfated V2O5/TiO2 catalyst between 280∼500 C. The surface structure of vanadia species on the catalyst surface played a critical role in the high performance of catalysts in which the existence of monomeric/polymeric vanadate is revealed by Raman spectra studies. Water vapor and SO2 were added to the reacting system for the catalyst deactivation tests. At higher temperatures (T ≥ 350 C), little deactivation was observed over the sulfated V2O5/TiO2 catalysts, showing good durability against SO2 and water vapor, which is compared with deactivation at lower temperatures.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1854-1856
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• 2007

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2361-2367
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• 2010

$TiO_2-ZrO_2$ was prepared with surfactant through a sol-gel method. Catalysts containing 5 - 35% $H_3PO_4$ were prepared using these oxides. Subsequently the catalytic performance of prepared catalysts was determined for liquid phase esterification of aromatic acids. $H_3PO_4/TiO_2-ZrO_2$ has been used as catalyst to synthesize various novel esters by esterification of some aromatic acids with aliphatic alcohols (2-propanol, 1-butanol, iso butanol, 3-pentanol, 1-hexanol, heptanol, cyclo heptanol, octanol and decanol). Under optimized conditions, maximum yields and selectivity (100%) to the corresponding ester, was obtained by using 25 wt % $H_3PO_4/TiO_2-ZrO_2$ as catalyst. The Catalyst can be easily recycled after reaction and can be reused without any significant loss of activity/selectivity performance. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present synthetic protocol. The reaction was carried out under solvent-free condition.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2311-2315
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• 2011

Alumina supported polyphosphoric acid (PPA/$Al_2O_3$) was successfully prepared by impregnation of alumina support by polyphosphoric acid and characterized using FT-IR spectroscopy, the $N_2$ adsorption/desorption analysis (BET), thermal analysis (TG/DTG), and X-ray diffraction (XRD) techniques. The catalytic behavior of this new solid acid supported heterogeneous catalyst was checked in the synthesis of 14-aryl-14H-dibenzo[a, j]xanthenes by cyclocondensation reaction of ${\beta}$-naphthol and aryl aldehydes under solvent-free conditions. The results showed that the novel catalyst has high activity and the desired products were obtained in very short reaction times with high yields. Moreover, the catalyst can be easily recovered by filtration and reused at least three times with only slight reduction in its catalytic activity.

• 한국대기환경학회지
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• 제16권5호
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• pp.529-537
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• 2000

Several Pt-based oxidation catalysts with different loading were prepared with various metal precursor solutions and characterized with H$_2$ chemisorption and TEM for Pt particle size. V was added to Pt-based catalyst for inhibiting SO$_2$oxidation reaction, as result, Pt-V/Ti-Si catalyst prepared by ERMS(Free Reduced Metal in Solution) method showed high enough activity and better inhibition on SO$_2$oxidation than Pt only catalyst. Optimum Pt particle size for diesel oxidation reaction turned out to be the size of around 20 nm. A prototype catalyst was prepared for light=duty diesel passenger car, and teated for the emission reduction performance with Korean regulation test mode(CVS-75 mode) on chassis dynamometer. The catalyst shows the performance reduction of 75~94% for CO, 53~67% for HC and 10~31% for PM. In the case of heavy-duty diesel catalyst, the domestic formal regulation teat mode D-13 was adopted for both Na engine and Turbo engine. The conversions of CO and THC are high enough(86% and 41%) while the reductions of NOx and PM are relatively low(3~11%).

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1741-1744
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• 2013

A new polymeric catalyst was prepared by supporting $GaCl_3$ on cross-linked polyvinylpyrrolidone ($GaCl_3$/PVP). This catalyst was employed for efficient and regioselective ring-opening reaction of epoxides by various alcohols under solvent-free conditions at room temperature. In our procedure, this heterogeneous catalyst was used at neutral and mild reaction conditions to afford high yields of ${\beta}$-alkoxy alcohols. Also, regioselective conversion of epoxides to ${\beta}$-azidohydrines was accomplished by sodium azide in MeOH in the presence of $GaCl_3$/PVP at room temperature. $GaCl_3$/PVP is a non-hygroscopic and recoverable catalyst and is easily separated from reaction mixture by a simple filtration and re-used repeatedly. Also, this catalyst has good handling and can be stored for long time without any reducing of its reactivity.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.179-185
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• 2009

The esterification of the reactants of Jatropha oil and methanol added by propyleneglycol was done using p-TSA catalyst. And then the emulsification of triglyceride and methanol was conduced by 1.0vol% GMS. The emulsified reactants were transesterified at $65^{\circ}C$ using TMAH and mixed catalyst (50wt%-TMAH+50wt%-NaOH) respectively. The esterification conversion at the 1:8 molar ratio of free fatty acid to methanol using 8.0wt% p-TSA was 94.7% within 80min. The overall conversion at the 1:8 molar ratio of mixed fat(50wt% Beef Tallow) to methanol and $65^{\circ}C$ using mixed catalyst was 95.4% The cloud point of Biodiesel decreased with the addition of petroleum diesel.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2367-2374
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• 2013

Lysine (Lys) immobilized on zeolite 4A was prepared by a simple adsorption method. The physical and chemical properties of Lys/zeolite 4A were investigated by X-ray diffraction (XRD), FT-IR, Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis. The obtained organic-inorganic composite was effectively employed as a heterogeneous basic catalyst for synthesis of ${\alpha},{\beta}$-unsaturated carbonyl compounds. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present catalyst.

• 대한화학회지
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• 제55권3호
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• pp.486-489
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• 2011

Potassium dihydrogen phosphate는 마이크로파 조사조건에서 용매 없이 페놀과 아세토아세트산 에틸의 Pechmann 축합반응에 의하여 쿠마린을 합성하는 효과적인 촉매로 밝혀졌다. 이 방법은 쿠마린 합성에 있어서 소량의 촉매를 필요로 하며 수율이 높고, 반응이 깨끗할 뿐만 아니라 반응 시간이 짧은 장점들을 가지고 있다.