• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1957-1964
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• 2011

Various reaction conditions uding temperature, time and type and concentration of templates have been changed in order to facilely synthesize, especially with microwave (MW) heating, SAPO-34 molecular sieves. SAPO-34 molecular sieve can be synthesized rapidly with microwave irradiation from a gel containing tetraethylammonium hydroxide (TEAOH) as a template. However, other several templating molecules lead to SAPO-5 molecular sieve under microwave irradiation even though SAPO-34 is obtained by conventional electric synthesis from the same reactant gels. Moreover, SAPO-34 can be obtained more easily by increasing the TEAOH or silica concentration or by increasing the reaction temperature. SAPO-34 can be obtained within 5 min in a selected condition (high temperature of 210 $^{\circ}C$) with microwave heating, which may lead to a continuous production of the important material. SAPO-34 synthesized by microwave irradiation is homogeneous and small in size and shows acidity and a stable performance in the dehydration of methanol and 2-butanol to olefins, suggesting potential applications in acid catalysis.

• Journal of the Korean Chemical Society
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• v.50 no.1
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• pp.53-59
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• 2006

.FAPO-5 molecular sieves were synthesized starting from the same reactant gel at 170 oC using microwave irradiation technique and conventional hydrothermal reaction. The FAPO-5 molecular sieves were characterized by several techniques such as SEM, FTIR, UV/Vis, and ESR. Moreover, the oxidation of styrene over FAPO-5s was carried out, and compared to check the oxidation and epoxidation ability of the two FAPO-5s. FAPO-5 can be obtained easily by microwave irradiation within 15 min at 170oC, whereas FAPO-5 synthesis is completed in 6 h by conventional electric heating, confirming the acceleration about 20 times by microwave technique. There are no appreciable differences between two FAPO-5s in surface area and coordination state of iron. The FAPO-5 synthesized by microwave irradiation shows higher epoxide selectivity in the styrene epoxidation, which may be explained by the higher hydrophobicity of the catalyst.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.01a
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• pp.30-30
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• 2002

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.18-23
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• 1992

Three solid acid catalysts developed recently are reviewed. Cloverite is a gallophosphate molecular sieve with very large pore, titanium silicate has a specific structure compared with conventional molecular sieves, and Envirocat is prepared for the replacement of aluminium chloride catalyst.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.558-562
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• 2005

Crystallization of SAPO-5 and SAPO-34 molecular sieves with microwave and conventional electric heating of the same gel has been investigated in an alkaline condition using N,N,N’N’tetraethylethylenediamine as a template molecule. SAPO-5 structure can be selectively prepared with microwave heating because of the fast crystallization of the technique. On the other hand, SAPO-34 is the sole product with usual conventional electric heating because SAPO-5 can be gradually transformed into SAPO-34 structure with an increase in crystallization time. This phase selectivity is probably because of the relative stability of the two phases at the reaction conditions (kinetic effect). Crystallization with microwave heating can be suggested as a phase selective synthesis method for relatively unstable materials because of fast crystallization.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.614-619
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• 2005

The activated carbon fibers of different surface area and pore structures were modified by carbon deposition from the pyrolysis of benzene, in an attempt to obtain carbon molecular sieves of high adsorption capacity and selectivity for the separation of $CO_2/CH_4$ gas mixtures. The ACFs molecular sieves prepared from different temperature and time were tested by the static adsorption of $CO_2$ and $CH_4$ gas, and their pore structures were characterized by the $N_2$ adsorption isotherms. We are able to prepare ACF molecular sieve with good selectivity for $CO_2/CH_4$ separation and showing acceptable adsorption capacities from the change of porosity by carbon deposition of pyrolyzed benzene.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.488-495
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• 2022

Activated carbon (AC) and carbon molecular sieve (CMS) have attracted attention as porous materials for recovery and separation of greenhouse gases. The carbon molecular sieve having uniform pores is used for collecting and separating gases because it may selectively adsorb a specific gas. The size and uniformity of pores determine the performance of the CMS, and chemical vapor deposition (CVD) is widely used to coat the surface with a predetermined thickness in order to control the CMS's micropores. This CVD method can be used to control the size of pores in CMS manufacturing, but it must be optimized because of its various experimental variables. Therefore, in order to produce AC and CMS for gas adsorption and separation, this review focuses on various activation processes and pore control technologies by CVD and surface treatment.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.235-242
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• 2006

Liquid phase alkylation of biphenyl (BP) was studied over large pore zeolites. Selective formation of the least bulky products, 4,4'-diisopropylbiphenyl (4,4'-DIPB) occurred only in the isopropylation of BP over some large pore molecular sieves. H-mordenites (MOR) gave the highest selectivity among them. The dealumination of MOR enhanced catalytic activity and the selectivity of 4,4'-DIPB because of the decrease of coke-deposition. Non-selective catalysis occurs on external acid sites over MOR with the low $SiO_2/Al_2O_3$ ratio because severe coke-deposition deactivates the acid sites inside the pores by blocking pore openings. The selectivity of DIPB isomers was changed with reaction temperature. Selective formation of 4,4'-DIPB was observed at moderate temperatures such as $250^{\circ}C$, whereas the decrease of the selectivity of 4,4'-DIPB occurred at higher temperatures as $300^{\circ}C$. However, 4,4'-DIPB was almost exclusive isomer in the encapsulated DIPB isomers inside the pores even at high temperatures. These decreases of the selectivity of 4,4'-DIPB are due to the isomerization of 4,4'-DIPB on the external acid sites. Some 12-membered molecular sieves, such as SSZ-24, MAPO-5 (M:Mg, Zn, Si), SSZ-31, and ZSM-12, which have straight channels, gave 4,4'-DIPB with moderate to high selectivity; however; SSZ-55, SSZ-42, and MAPO-36 (M: Mg, Zn) gave lower selectivity because of cages in 12-membered one dimensional channels. Three dimensional H-Y and Beta zeolites also yield 4,4'-DIPB in low yield because of their wide circumstances for the isopropylation of BP. The increasing the size of alkylating agent enhanced the shape-selective alkylaiton even for the zeolites, such as UTD-1. The ethylation of BP to ethylbiphenyls (EBPs) and diethylbiphenyls (DEBPs) over MOR was non-selective. The ethylation of BP to EBPs was controlled kinetically. However, there was difference in reactivity of EBPs and DEBPs for their further ethylation. 4-EBP was ethylated preferentially among the isomers, although the formation of 4,4'-DEBP was less selective. The least bulky 4-EBP and 4,4'-DEBP have the highest reactivity among EBPs and DEBPs for the ethylation to polyethylbiphenyls (PEBPs). These results show that the environments of MOR pores are too loose for shape selective formation of the least bulky isomers, 4-EBP and 4,4'-DEBP in the ethylation of BP, and that MOR pores have enough space for the further ethylation of 4,4'-DEBP.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.63-67
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• 2002

우리나라는 1970 년대부터 급속한 경제발전과 더불어 생활수준의 향상에 따른 소비 성향의 변화 및 인구의 도시집중화현상 등으로 도시 쓰레기의 배출의 변화가 나타나서, 배출된 쓰레기의 양은 매년 증가되는 추세이다. 또한 배출된 쓰레기의 80% 이상을 단순 매립에 의존하는 처리방식이므로(환경부,1995), 유기성 폐기물이 혐기 소화되면서 다량의 가스와 침출수를 발생시켜 주변 지역의 자연 및 생활환경에 악영향을 미치며, 환경적, 사회적으로 큰 문제가 대두되고 있는 현실이다.(중략)

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.239-244
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• 2004