• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.61-71
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• 1992

Through the low-temperature(60-150${\circ}C$) hydrothermal treatment of perlite with the alkaline solution at various NaOH concentrations, the mode of volcanic glass alteration and resultant zeolite formation were investigated in a closed system. At a temperature of 80${\circ}C$ and alkalinities of pH range 8 to 12, corresponding to the natural environments of diagenetic zeolite formation, only weak dissolution of perlitic glass occurs without zeolite formation despite the residence time of 100 days. Activities of Si and Al increase progressively, as a consequence of increasing pH, whereas activity ratios of Si/Al decrease. Zeolites were synthesized from perlite in the alkaline solution at above 0.1M NaOH concentrations. Below the temperature of 100${\circ}C$ Na-P was mainly formed, whereas analcime was the dominant zeolite at the temperature range of 100-150${\circ}C$. During Na-P synthesis chabazite and Na-X were also formed as by-products in case of lower proportion of solution/sample(<10ml/g) and higher NaOH concentraion (>3M), respectively. The alteration modes of perlite in the zeolite synthesis reflect that the formation of synthetic zeolites occurs as an incongruent dissolution likely with the diagenetic formation of natural zeolites from volcanic glass. Considering much difference in reaction kinetics between natural and synthetic systems, however, the evaluated synthetic conditions in these experiments were not directly applicable to the natural diagenetic system.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.48-48
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• 2003

미세기공(microporous)을 가진 제올라이트는 다양한 유기질 분리의 촉매제 및 광학, 화학 센서, 기체 분리 등의 고기능 소재로서 크게 주목받고 있으며, 비표면적의 증가, 새로운 기능의 발현 둥으로 최근 들어 나노크기를 갖는 제올라이트 합성에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 기체 분리에 응용하기 위한 제올라이트 분리막 개발에 앞서 분리막 제조에 유리할 것으로 판단되어지는 적합한 크기와 형상을 갖춘 나노크기의 제올라이트를 합성하였으며 그 특성을 분석하였다. 출발물질로서 실리카 원으로는 TEOS, LUDOX AS-40, Cab-O-SIL 등을 사용하였으며, 템프레이트(TPAOH)와 함께 특정조성의 TPAOH/SiO$_2$,/$H_2O$ 겔을 만들었다. 합성시간을 단축할 수 있는 방법의 연구로서 저온하의 2단계 온도 변화법을 적용하였으며, 결정성장속도의 향상을 목적으로 NaH$_2$PO$_4$, H$_2$SO$_4$, NH$_4$OH 등의 결정화 촉진제로 사용하여 수열합성법으로 Silicalite-1를 합성하였다.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.203-207
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• 2013

Zeolites with different structures were synthesized from the hydrothermal synthesis condition employing simple structure directing agent (SDA) containing piperidine moiety. The gel containing $1.0SiO_2$:0.9SDA:$0.062NaAlO_2$:0.217NaOH:$20H_2O$ was subject to hydrothermal synthesis at 413~453 K for 7 days. FER type zeolite was obtained at 433 K when piperidine was employed as SDA, whereas TON and MFI type zeolites were also obtained at 433 K when 2,6-dimethylpiperidine and 2,2,6,6-tetramethylpiperidine were used, respectively. Further increase of hydrothermal synthesis temperature to 453 K resulted in the formation of TON type zeolite when 2-mtheylpiperidine was used. The structural analysis of powder X ray diffraction pattern over FER type zeolite suggested that the SDA, piperidine interacted intimately with the zeolite where it located close to the framework.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.179-182
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• 2002

기존의 적정 자료로부터 구하는 방법이 아닌 흡착제의 Zeta potential 자료를 바탕으로 구한 값으로도 흡착결과를 잘 모사할 수 있다. 합성 제올라이트의 중금속 이온 제거능은 합성 제올라이트의 종류에 따라서는 중금속 이온의 종류에 관계없이 Na-Pl > SOD > CAN > ANA의 순서로 감소하였다. SCM 모델링의 Fitting을 결정하는 Fitting 변수로서는 총 site 농도(g/$\ell$), site 밀도 (sites/$nm^2$), 비표면적 ($m^2$/g)으로써 결정할 수 있다.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.286-289
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• 2017

Synthesis of zeolite 4A was carried out to optimize the nanoparticle synthesis process using statistical experimental design method. The zeolite 4A was synthesized by controlling the concentration of the silicon precursor, sodium metasilicate (SMS), and characterized by XRD, SEM and nitrogen adsorption. In particular, the property of zeolite 4A can be determined by XRD analysis. Using the general factor analysis in the design of experiments, we analyzed main effects and interactions according to the reactor, reaction temperature and reaction time. The optimum reaction condition for the synthesis of zeolite 4A crystallinity was using an autoclave for 3 hours at $110^{\circ}C$. Furthermore, the optimal synthesis conditions of zeolite 4A with various crystallinity using Ludox as a silicon precursor were presented of what using both the surface and contour plot.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.29-29
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• 1997

ZSM-5계 제올라이트는 직경이 약 6${\AA}$인 균일한 3차원 채널 형태의 기공을 형성하므로 이를 이용한 기체 분리막은 분자체가름(molecular sieving)이나 미세기공확산(micropore diffusion) 및 표면확산(surface diffusion) 메커니즘에 의해 최근 지구 온난화의 주범으로 지목되고 있는 CO$_2$ 기체에 대해 높은 분리 효율을 기대할 수 있으므로 ZSM-5 복합분리막의 제조 및 기체 투과 특성과 CO$_2$ 분리 특성에 대해 연구하였으며 다음과 같은 결과를 얻을 수 있었다. 콜로이달 실리카 졸에 질산 알루미늄, 수산화 나트륨 및 TPABr을 첨가한 혼합졸과 물유리를 증류수로 희석한 후 TPBr을 첨가한 용액을 각각 150~180${\AA}$의 온도 범위의 오토클레이브에서 수열 처리하여 ZSM-5와 실리카라이트를 합성하였다. 합성 제올라이트의 결정 구조는 사방정이었으나 450${\AA}$에서 하소하였을 때에는 단사정으로 전이됨과 동시에 채널 속을 채우고 있던 TPABr이 제거되면서 제올라이트의 3차원 채널 형태의 기공 구조가 생성되었다. 제올라이트 결정의 형상과 크기는 실리카 공급원과 반응용액/졸의 농도에 따라 매우 민감하게 변화되었다. 하소 제올라이트의 비표면적은 약 360 m$^2$/g 이었다. 합성 제올라이트의 표면은 소수성인 반면에 높은 CO$_2$ 흡착능을 갖고 있어서 CO$_2$ 분리용 막의 재료로써 적합하였다.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.615-618
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• 1998

The zeolite crystals were synthesized by hydrogel process into the pore of activated carbon. The effect of activated carbon in the course of the crystallization of zeolite was investigated. The phenomena of impregnation of zeolite crystals into the pore of the activated carbon were also examined. The results show that in case of the addition of 5% of activated carbon to the aluminosilicate gel including the mole composition of zeolite A, zeolite A was purely synthesized without the existence of other type of zeolite. However, in case of the addition of 20% of activated carbon, zeolite X was purely synthesized. In the pore mouth and internal of activated carbon, zeolite crystals having the size under $1{\mu}m$ was observed. From the results of the pore size and particle size distributions, it was confirmed that the synthetic sample was the composite material impregnated by the zeolite crystals into the pore of activated carbon, not the simple mixture of zeolite and activated carbon.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.97-101
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• 2001

Phillipsite-type zeolite powders were synthesized from domestic coal fly ash by hydrothermal reaction with 2.0 M-3.5M NaOH solution at $80^{\circ}C{\sim}120^{\circ}C$ for 24 h. The properties of zeolite were investigated by XRD, SEM and IR spectroscopy. The effects of chemical composition of fly ash, reaction temperature and NaOH concentration on the zeolite synthesis were well appeared on IR spectra. It is found that the $TO_4$(T=Si, Al) tetrahedra have a well ordered structure as the $SiO_2$ content, synthesis temperature and NaOH concentration become high.

• Clean Technology
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• v.24 no.1
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• pp.21-26
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• 2018

The coal is a useful industrial resource for a long time. However, coal waste is generated by the mining process. Coal wastes are the main cause of pollution in the surrounding environment, and the amount of coal waste is set at hundreds of millions of tons. Significant amounts of these components in the coal waste are $SiO_2$ and $Al_2O_3$, which is also the main source of zeolites useful in various industries. This study is that the synthesis-zeolite was prepared from coal waste and properties and adsorption performance of synthesis-zeolite were compared with commercial zeolite. The synthesis-zeolite is showed similar properties to the commercial zeolite and also showed excellent adsorption performance against atmospheric pollution induced gases ($CO_2$, Toluene, $SO_2$, etc).

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.214-218
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• 2011

Zeolite A was synthesized from coal fly ash by the microwave heating as well as the conventional heating method. The effects of reaction time, the amount of sodium aluminate, and the reaction temperature on the crystallization of zeolite A were investigated. The optimum crystallization time was about 3 to 6 h in the temperature range of $80{\sim}100^{\circ}C$. The amount of sodium aluminate was found to be optimum when the molar ratio $SiO_2/Al_2O_3$ of starting solution was in the range of 0.44 to 1.05 at above $90^{\circ}C$, However, The more amount of sodium aluminate was required to get zeolite A at $80^{\circ}C$. Although the rate of crystallization was slightly faster in the microwave heating than that in the conventional heating, the reaction time need to obtain fully crystallized zeolite A was similar in both methods. Therefore, the influence of the microwave heating was not so large compared with the conventional heating in the synthesis of zeolite A from coal fly ash.