• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1457-1464
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• 2012

An ecofriendly catalytic route for selective synthesis of $N$-substituted azacyclopentanes, nitrogen-containing heterocyclic intermediates for many bioactive compounds, was established by carrying out $N$-heterocyclization (di $N$-alkylation) of primary amines with 1,4-dichloro butane (as dialkylating agent) using catalytic amount of hydrotalcite as solid base catalyst. The hydrotalcite was found to be efficient solid base catalyst for di $N$-alkylation of different primary amines (aniline, benzyl amine, cyclohexyl amine and n-butyl amine) giving 82 to 96% conversion (at optimized reaction condition) of 1,4-dichloro butane and > 99% selectivity of respective $N$-substituted azacyclopentanes within 30 min. under solvent free condition. The reaction parameters significantly influence the conversion of 1,4-dichloro butane to $N$-substituted azacyclopentanes. The nature of substituent present on amino group affects the reactivity of amine substrates for di $N$-alkylation reaction with 1,4-dichloro butane. The 1,4-dichloro butane was found to be highly reactive alkylating agent for di $N$-alkylation of amines as compared to 1,4-dihydroxy butane. The reusability of the catalyst and its chemical stability in the reaction was demonstrated.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.86-89
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• 2004

The present study reports the preparation of a compact ZSM-5 membrane showing high thermal stability and high separation factors, especially n-/i-butane isomers at high temperatures. ZSM-5 membrane was prepared on a porous $\alpha$-Al$_2$O$_3$ tube (an average pore diameter, ca. 100 nm) at 18$0^{\circ}C$ by the seed-assisted crystallization method. The XRD and SEM results showed that a thin zeolite layer (ca. 1 ${\mu}{\textrm}{m}$) was formed on the support surface. The single gas permeances of $N_2$, H$_2$, SF$_{6}$, n-butane, and i-butane were taken at 27$0^{\circ}C$. i-Butane permeance hardly changed after repeated thermal treatments up to 40$0^{\circ}C$, indicating the membrane is thermally stable. On the other hand, other single gas permeances increased when the membrane was further dried at 40$0^{\circ}C$, indicating thermal pretreatment at 27$0^{\circ}C$ could not remove all the adsorbed species in the membrane. i-Butane and SF$_{6}$ permeances were significantly lower than the permeances of smaller molecules, indicating that the membrane has a low concentration of defects. The ideal selectivities at 27$0^{\circ}C$ were 61 for $H_2$/i-butane and 47 for $H_2$/SF$_{6}$. The temperature dependency of n/i-butane ideal selectivities and separation factors for an equimolar n/i-butane mixture was studied. The ideal selectivity showed a maximum of 36 at 30$0^{\circ}C$. The separation factors increased with temperature and reached around 12 at 300-40$0^{\circ}C$, which were much higher than those reported in the literature.ature.

• Korean Chemical Engineering Research
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• 제44권4호
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• pp.393-398
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• 2006

고농도의 1-부텐을 생산하기 위하여 흡착 분리제의 개발이 필수적인데, 본 연구에서는 메조포러스 실리케이트인 MCM-41을 지지체로 하여 $AgNO_3$를 함침시켜 흡착제를 제조한 후, 1-부텐과 n-부탄의 흡착 특성을 연구하였다. 또한, 열처리 조건에 따른 $Ag^+$ 이온의 형성 비율과 1-부텐의 결합 능력을 알아보았다. MCM-41 흡착제의 경우, 13X 제올라 이트에 비하여 매우 높은 흡착량을 보여주었으며, 은이 담지되었을 때, n-부탄의 흡착량은 감소하는 반면에 1-부텐의 흡착량은 증가함으로써 1-부텐과 n-부탄의 흡착 분리에 매우 좋은 성능을 갖음을 확인할 수 있었다. 또한, 진공 분위기에서 373 K로 열처리한 Ag/MCM-41의 경우 가장 높은 1-부텐/n-부탄 흡착비를 보였으며, 특히 저압에서 매우 높은흡착비를 보여주었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제8권4호
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• pp.45-52
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• 2003

국내유류오염지역 토양에서 propane과 butane을 탄소원으로 이용하여 분리된 Nocardia SW3를 대상으로 가스기질농도, 온도, pH 변화에 따른 영향, 그리고 MTBE 공대사 분해 특성을 조사하였다. 초기농도변화에 따른 기질분해속도를 비교하면 propane 및 butane이 70$\mu$㏖일때 각각 30.6, 25.4(n㏖/min/mg protein)으로 관찰되어 빠른 기질이용율을 보여주었으며, 최적온도 및 pH조건은 $30^{\circ}C$, 7이었으며, 실험조건인 온도 $15^{\circ}C$∼$35^{\circ}C$. pH 5∼8 범위내에서 약간의 차이는 있지만 전반적으로 propane과 butane이 효율적으로 이용되었다. Nocardia SW3를 대상으로 propane 및 butane이 탄소원으로 이용될 때 MTBE분해특성을 비교ㆍ평가한 결과, propane 및 butane의 MTBE 분해 활성도는 유사하였으며, 가스기질이 탄소원으로 이용시 MTB표의 분해량을 나타내는 transformation yield($T_y$)는 propane과 butane의 경우 각각 46.7, 35.0(n㏖ MTBE degraded $\mu$㏖ substrate utilized), transformation capacity($T_c$)는 실험 결과 각각 320, 280(n㏖ MTBE degraded/mg biomass used)로 나타났다. 또한 MTBE 부산물로 TBA가 검출되었으며, TBA의 지속적인 분해를 관찰하였다.

• 청정기술
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• 제18권2호
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• pp.162-169
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• 2012

n-부탄의 탈수소화 촉매로 Pt와 Sn을 알루미나 지지체에 담지하기 위하여 함침법을 이용하여 Pt-Sn/${\theta}-Al_2O_3$ 촉매를 제조하였다. 물리적화학적 특성을 알아보기 위해 XRD, $N_2$ 흡탈착, $NH_3$-TPD, $H_2$-TPR 분석을 실시하였다. 또한 Pt-Sn/${\theta}-Al_2O_3$ 촉매상에서 탈수소반응에 대한 활성에 대한 영향을 관찰하기 위해서 전처리 온도, 전처리 시간, 반응온도, 공간속도에 따른 촉매의 활성에 대한 영향과 더불어 탈수소 반응에 대한 온도 조건에 따른 반응속도의 변화를 관찰하였다. 5~55% 부탄의 전환율 변화에 따른 부텐의 선택도 합은 95% 정도로 일정하게 유지되었다. 아레니우스식을 이용하여 얻은 활성화 에너지 $82.4kJ\;mol^{-1}$이었고, 멱함수를 이용하여 얻은 n-부탄 및 수소의 반응차수는 각각 0.70과 -0.20차로 나타났다.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권1호
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• pp.25-33
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• 2007

The investigation has been made into the prediction of heat exchange performance of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and micro-fin tube. Under various heat transfer conditions, mass flux, pressure drop and heat transfer coefficient of the mixed refrigerants were calculated using a prediction method, when the length of condensing tube, total heat transfer rate, mass flux and outlet temperature of coolant were maintained constant. Also, the predicted results were compared with those of HCFC22. The results showed that the mixed refrigerants of Propane/n-Butane or Propane/i-Butane could be substituted for HCFC22, while the pressure drop and overall heat transfer coefficient of the refrigerants were evaluated together.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.735-744
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• 1996

We present results of molecular dynamic (MD) simulations for the thermodynamic and structural properties of liquid n-alkanes, from n-butane to n-heptadecane, using three different models Ⅰ-Ⅲ. Two of the three classes of models are collapsed atomic models while the third class is an atomistically detailed model. Model Ⅰ is the original Ryckaert and Bellemans' collapsed atomic model [Discuss. Faraday Soc. 1978, 66, 95] and model Ⅱ is the expanded collapsed model which includes C-C bond stretching and C-C-C bond angle bending potentials in addition to Lennard-Jones and torsional potentials of model Ⅰ. In model Ⅲ all the carbon and hydrogen atoms in the monomeric units are represented explicitly for the alkane molecules. Excellent agreement of the results of our MD simulations of model Ⅰ for n-butane with those of Edberg et al.[J. Chem. Phys. 1986, 84, 6933], who used a different algorithm confirms the validity of our algorithms for MD simulations of model Ⅱ for 14 liquid n-alkanes and of models Ⅰ and Ⅲ for liquid n-butane, n-decane, and n-heptadecane. The thermodynamic and structural properties of models Ⅰ and Ⅱ are very similar to each other and the thermodynamic properties of model Ⅲ for the three n-alkanes are not much different from those of models Ⅰ and Ⅱ. However, the structural properties of model Ⅲ are very different from those of models Ⅰ and Ⅱ as observed by comparing the radial distribution functions, the average end-to-end distances and the root-mean-squared radii of gyrations.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.45-48
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• 2015

• Macromolecular Research
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• 제11권4호
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• pp.231-235
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• 2003

Phase behavior information is necessary for accomplishing homogeneous copolymerization to obtain high yield of copolymers and prevent a fouling problem. Cloud-point data to $160^{\circ}C$ and 1,450 bar are presented for five $C_6$ hydrocarbon solvents, normal hexane, 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane, with poly(ethylene-co-53 mol% norbornene) ($PEN_{53}$). The pressure-concentration isotherms measured for $PEN_{53}$/n-hexane have maximums that range between 5 and 12 wt% $PEN_{53}$. The cloud-point curves for $PEN_{53}$ all have negative slopes that decrease in pressure with temperatures. The single-phase region of $PEN_{53}$ in n-hexane is larger than the regions in 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane. The cloud-point curve of $PEN_{53}$ in 2,2-dimethyl butane is located at higher temperatures and pressures than the curve in 2,3-dimethyl butane due to the reduced dispersion interactions with and limited access of 2,2-dimethyl butane to the copolymer. Similar cloud-point behavior is observed for $PEN_{53}$ in 2-methyl pentane and 3-methyl pentane.

• 한국분무공학회지
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• 제19권1호
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• pp.1-8
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• 2014

Liquefied petroleum gas (LPG) is regarded as an alternative fuel for spark ignition engine due to similar or even higher octane number. In addition, LPG has better fuel characteristics including high vaporization characteristic and low carbon/hydrogen ratio leading to a reduction in carbon dioxide emission. Recently, development of LPG direct injection system started to improve performance of vehicles fuelled with LPG. However, spray characteristics of LPG were not well understood, which is should be known to develop injector for LPG direct injection engines. In this study, effects of operation condition including ambient pressure, temperature, and injection pressure on spray properties of n-butane were evaluated and compared to gasoline in a multi-hole injector. As general characteristics of both fuels, spray penetration becomes smaller with an increase of ambient pressure as well as a reduction in the injection pressure. However, it is found that evaporation of n-butane was faster compared to gasoline under all experimental condition. As a result, spray penetration of n-butane was shorter than that of gasoline. This result was due to higher vapor pressure and lower boiling point of n-butane. On the other hand, spray angle of both fuels do not vary much except under high ambient temperature conditions. Furthermore, spray shape of n-butane spray becomes completely different from that of gasoline at high ambient temperature conditions due to flash boiling of n-butane.