• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.521-523
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• 2009

본 연구에서는 식물성유지와 메탄올로부터 전이에스테르화 반응에 의해 바이오디젤 제조에 사용되는 비균질촉매로 사용하기 위하여 NaX 제올라이트 촉매에 염기도를 향상시키기 위하여 KOH를 담지하여 담지량에 따른 바이오디젤 제조특성을 조사해보았다. KOH 담지량을 10wt% - 70wt%로 달리하여 Incipient wetness 방법으로 담지한후 $500^{\circ}C$에서 소성하여 촉매를 제조하고, 제조된 KOH의 담지량이 다른 KOH/NaX 제올라이트 촉매는 SEM, XRD, BET등을 통해 촉매특성을 평가하였고, 생성된 지방산 메틸에스테르는 가스크로마토그래피로 순도를 측정하였다. NaX 제올라이트 촉매에 KOH 담지량이 높은 경우와 촉매량이 많은 경우 바이오디젤제조에 유리하였고, 특히 반응시간과 반응온도는 $120^{\circ}C$, 2시간동안 반응한 경우 가장 좋은 지방산 메틸에스테르의 수율을 얻을 수 있었다.

• 한국환경과학회지
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• 제29권12호
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• pp.1261-1274
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• 2020

The characteristics of ammonia-nitrogen (NH4+-N) adsorption by a zeolitic material synthesized from Jeju scoria using the fusion and hydrothermal method was studied. The synthetic zeolitic material (Z-SA) was identified as a Na-A zeolite by X-ray diffraction, X-ray fluorescence analysis and scanning electron microscopy images. The adsorption of NH4+-N using Jeju scoria and different types of zeolite such as the Z-SA, natural zeolite, and commercial pure zeolite (Na-A zeolite, Z-CS) was compared. The equilibrium of NH4+-N adsorption was reached within 30 min for Z-SA and Z-CS, and after 60 min for Jeju scoria and natural zeolite. The adsorption capacity of NH4+-N increased with approaching to neutral when pH was in the range of 3-7, but decreased above 7. The removal efficiency of NH4+-N increased with increasing Z-SA dosage, however, its adsorption capacity decreased. For initial NH4+-N concentrations of 10-200 mg/L at pH 7, the adsorption rate of NH4+-N was well described by the pseudo second-order kinetic model than the pseudo first-order kinetic model. The adsorption isotherm was well fitted by the Langmuir model. The maximum uptake of NH4+-N obtained from the Langmuir model decreased in the order of Z-CS (46.8 mg/g) > Z-SA (31.3 mg/g) > natural zeolite (5.6 mg/g) > Jeju scoria (0.2 mg/g).

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.783-791
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• 2008

Li-X 제올라이트 흡착탑에서의 $H_2/CO_2$(80:20 vol%), $H_2/CO$(90:10 vol%), $H_2/CH_4$(90:10 vol%)의 이성분계 기체의 흡착 동특성을 연구하였다. 각 계에서 공급유속(6.24~10.24 LPM), 흡착압력(6.1~10.1 bar)에 대한 영향을 살펴보았다. 동특성 실험 결과 파과시간은 공급유속이 적을수록, 흡착압력이 높을수록 증가하였으며 탑 내부 온도의 영향으로 tailing 현상이 발생하였다. Li-X 제올라이트 흡착탑에서 공급 유량과 압력의 확산계수에 의한 LDF식을 사용하여 예측하였다. 본 연구에서는 비등온과 비단열상태, Dual-site langmuir 등온식과 고려하여 해석하였으며 실험 데이터와 비교하였다.

• 대한화학회지
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• 제17권1호
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• pp.47-52
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• 1973

우리나라 영일산 Bentonite를 0.5-6 N NaOH로 $70-90^{\circ}C$에서 $Na_2:SiO_2$의 비율로 $1:1{\sim}4:1$로 2-30일의 범위에서 처리하여 그 겨정성의 변화를 X선회절법으로 조사하였다. 그 결과 2N NaOH로 $70^{\circ}C$에서 Zeolite Species가 좋은 수율로 생성되었다. 그러나 NaOH의 농도가 더 크고 온도가 더 높으면 이 Zeolite는 Hydrozysodalite로 변한다. 이 결정 외에도 처리조건에 따라서는 raujasite, sodium A zeolite, mordemite등의 결정도 소량 생겼다.

• 한국환경과학회지
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• 제24권9호
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• pp.1145-1153
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• 2015

PVC-Zeolite composite was prepared by immobilizing zeolite with polyvinyl chloride (PVC). The prepared PVC-Zeolite beads were characterized by using X-ray diffractometer (XRD), fourier transform infrared spectrometer (FTIR), thermo gravimetric analyzer (TGA), and scanning electron microscopy (SEM). The removal properties of Sr and Cs ions from aqueous solution were investigated in batch experiment. The removal efficiencies of Sr and Cs ions by the PVC-Zeolite beads were dependent on the initial pH of solution. The removal efficiencies sharply increased at below pH 4 and was kept constant at pH 4 or more. The adsorption kinetics of Sr and Cs ions by the PVC-Zeolite beads were fitted well by the pseudo-second-order model ($r^2$>0.99) more than pseudo-first-order model. The maximum adsorption capacities of Sr and Cs ions calculated from Langmuir isotherm model were 39.37 mg/g and 55.87 mg/g, respectively.

• Macromolecular Research
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• 제15권7호
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• pp.662-670
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• 2007

The crystallization behavior and fine structure of poly(ethylene terephthalate) (PET)/A-zeolite nanocomposites were assessed via differential scanning calorimetry (DSC) and time-resolved small-angle X-ray scattering (TR-SAXS). The Avrami exponent increased from 3.5 to approximately 4.5 with increasing A-zeolite contents, thereby indicating a change in crystal growth formation. The rate constant, k, evidenced an increasing trend with increases in A-zeolite contents. The SAXS data revealed morphological changes occurring during isothermal crystallization. As the zeolite content increased, the long period and amorphous region size also increased. It has been suggested that, since PET molecules passed through the zeolite pores, some of them are rejected into the amorphous region, thereby resulting in increased amorphous region size and increased long period, respectively. In addition, as PET chains piercing into A-zeolite pores cannot precipitate perfect crystal folding, imperfect crystals begin to melt at an earlier temperature, as was revealed by the SAXS profiles obtained during heating. However, the spherulite size was reduced with increasing nanofiller content, because impingement between adjacent spherulites in the nanocomposite occurs earlier than that of homo PET, due to the increase in nucleating sites.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1095-1099
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• 1998

The crystal structure of an acetylene sorption complex of dehydrated fully Mn(Ⅱ)-exchanged zeolite X, Mn46Si100Al92O384·30C2H2 (a=24.705(3) Å) has been determined by single-crystal X-ray diffraction techniques. The structure was solved and refined in the cubic space group Fd3 at 21(l) ℃. The complex was prepared by dehydration at 380 ℃ and 2 x 10-6 Torr for 2 days, followed by exposure to 300 Torr of acetylene gas for 2 h at 24 ℃. The structure was refined to the final error indices, R1=0.060 and R2=0.054 with 383 reflections for which I > 3σ(Ⅰ). In the structure, Mn2+ ions are located at two different crystallographic sites; sixteen Mn2+ ions at site I are located at the centers of the double six rings and thirty Mn2+ ions are found at site Ⅱ in the supercage, respectively. Each of these latter Mn2+ ions is recessed ca. 0.385(2) Å into the supercage from its three-oxygen plane. Thirty acetylene molecules are sorbed per unit cell. Each Mn2+ ion at site Ⅱ lies on a threefold axis in the supercage of the unit cell, close to three equivalent trigonally arranged zeolite framework oxygen atoms (Mn(Ⅱ)-O=2.135(9) Å) and symmetrically to both carbon atoms of a C2H2 molecules. At these latter distances, the Mn(Ⅱ)-C interactions are weak (Mn(Ⅱ)-C=2.70(5) Å), probably resulting from electrostatic attractions between the divalent cations and the polarizable π-electron density of the acetylene molecules.

• Bulletin of the Korean Chemical Society
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• 제23권12호
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• pp.1759-1764
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• 2002

Two crystal structures of dehydrated $Ag^+-andTl^+$-exchanged zeolite X$Ag_{27}Tl_{65-}X\;and\;Ag_{23}Tl_{69-}X$have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21(1) $^{\circ}C(a=24.758(4)\AAa=24.947(4)$, ${\AA}respectively).$, Their structures were refined to the final error indices $R_1$=0.055 and $wR_2$=0.057 with 375 reflections, and $R_1$=0.057 and $wR_2$=0.057 with 235 reflections, respectively, for which I > $3\sigma(I).$ In the structure of $Ag_{27}Tl_{65-}X,\;27\;Ag^+$ ions were found at two crystallographic sites: 15$Ag^+$ ions at site I at the center of the hexagonal prism and the remaining 12$Ag^+$ ions at site II' in the sodalite cavity. Sixty-five $Tl^+$ ions were located at three crystallographic sites: 20$Tl^+$ ions at site II opposite single six-rings in the supercage, 18$Tl^+$ ions at site I' in the sodalite cavity opposite the D6Rs, and the remaining 27$Tl^+$ ions at site III' in the supercage. In the structure of $Ag_{23}Tl_{69-}X$, 23$Ag^+$ ions were found at two crystallographic sites: 15 at site I and 8 at site II'. Sixty-nine $Tl^+$ ions are found at four crystallographic sites: 24 at site II, 17 at stie I', and the remaining 28 at two III' sites with occupancies of 22 and 6.

• 분석과학
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• 제21권1호
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• pp.58-63
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• 2008

수열합성법으로 합성 제조한 TMA-A 제올라이트 내부에 이온교환법을 이용하여 나노 사이즈의 ZnO 결정을 성공적으로 담지하였다. TMA-A 제올라이트의 최적 합성 조성비로는 $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$로 된 용액이었다. ZnO를 담지시킨 TMA-A 제올라이트의 합성을 위하여 0.3g의TMA-A 제올라이트와 5몰의 $ZnCl_2$ 용액을 사용하였다. ZnO 결정를 담지시킨 TMA-A 제올라이트의결정화 과정을 X-ray diffraction (XRD)를 이용하여 분석하였다. 담지된 나노 크기의 ZnO결정과 TMA-A 제올라이트의 결정성을 투과전자현미경과 고배율 투과전자현미경으로 평가하였다. 담지된 ZnO 나노 결정의 크기는 3~5 nm이었으며, 합성된 TMA-A 제올라이트의 크기는 60~100 nm 이었다. FT-IR분석으로 열처리 전 및 열처리 후 ZnO결정를 담지시킨 TMA-A 제올라이트의 결합구조를 확인하였으며, ZnO 및 TMA-A 제올라이트의 흡수 스펙트럼을 비교 평가하였다. 또한, 자외선분광기의 측정에서, ZnO결정를 담지한 TMA-A 제올라이트가 330~260 nm과 260~230 nm 두 파장의 범위에서 형광학적인 특성을 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.83-84
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• 2008

바이오 디젤은 석유기반 연료들을 대신할 수 있는 대체연료일 뿐만 아니라 재생가능자원으로부터 얻을 수 있다는 장점을 가지고 있다. 바이오 디젤은 동 식물성 유지를 이용해서 알코올과 촉매 존재하에서 제조되며, 주로 KOH, NaOH 등 균질촉매를 이용하여 제조하는데 이는 폐수 발생이 많고 공정 비용이 많이 든다는 단점이 있다. 따라서 최근에는 폐기물 발생이 없고 촉매의 제거가 편리한 비균질촉매의 개발이 이루어지고 있다. 본 연구에서는 NaX 제올라이트 촉매에 KOH를 담지시켜 염기도의 증가에 따라 바이오디젤의 제조특성에 미치는 촉매특성을 조사해 보았다. NaX 제올라이트 촉매에 KOH 담지량이 증가와 반응시간이 증가함에 따라 바이오디젤 생성량은 증가하였다.