• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.600-606
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• 2018

The influence of acidity in MTT zeolite of different Si/Al molar ratio's on the catalyst activity in methanol-to-olefin (MTO) reaction has been investigated. The Si/Al ratio was controlled with the Al content in the gel when N,N,N',N'-tetramethyl-1,3-diaminopropane was used as a structure directing agent (SDA). The gel composition was controlled to $20SiO_2$ : 30SDA : x (=0.25~1.25)$NaAlO_2$ : 2NaOH : $624H_2O$, which was subject to the hydrothermal synthesis at 433 K for 4 days. As the composition of sodium aluminate decreased, the particle size of MTT zeolite increased, and also the amount of acid sites decreased. To investigate the catalytic performance, MTO reaction was carried out at 673 K with $1.2h^{-1}$ WHSV. It was found that the H-MTT (1.00Al) catalyst with a Si/Al molar ratio of 24 maintained the methanol conversion over 90% for 900 min.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.714-721
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• 1994

Titanium and zirconium-containing MFI type zeolites have been prepared hydrothermally. Incorporation of titanium or zirconium into the framework of zeolite has been demonstrated by XRD, FT-IR, $^{29}Si$ MAS NMR analysis, and the catalytic benzene hydroxylation or n-hexane oxidation was used for checking the properties of catalysts. Pure titania and zirconia powder showed no catalytic activity at all for these reactions but Ti and Zr modified zeolite had the high activities in both reactions. The catalytic activity strongly depended on the kind of solvents, and the conversion of benzene or n-hexane increased with the increasing content of Ti and Zr in zeolites.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.857-864
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• 2005

Dealuminated and alkali/alkaline-earth metal exchanged Y-type and ZSM-5 zeolites were prepared as catalytic materials. Comparing with the composition of starting material, the magnitude of Si/Al ratio was increased after dealumination and cation exchange process. The ratio of Si/Al on surface was appeared to be larger than that in bulk. The destruction of basic frame in catalysts observed was understood to be due to a detachment of aluminum, which results in reducing framework while increasing non-framework. This phenomenon becomes more serious with increasing time of steam treatment and even more significant for the cation exchanged catalysts. The desorption peaks of the NO-TPD profiles taken after dealumination and cation exchanged Y-type and ZSM-5 zeolites shifted to the low temperature region. It was also found that the longer the steam treatment time, the degree of shift toward low temperature region was increased. The catalytic activities are dependent on the nature of cation exchanged, the ratio of Si/Al and the ratio of framework/non-framework by a change in basic frame.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.382-386
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• 2006

Rice straw is one of the main renewable energy sources in Korea. Bio-oil is produced from rice straw with a bench-scale equipment mainly with a fluidized bed, a char removal system and zeolite catalyst. It was investigated how the zeolite catalyst affected the production of bio-oil and chemical composition of bio-oil. Compared with non catalytic pyrolysis, the catalytic pyrolysis increased the amount of gas and char but decreased the amount of oil. The water content in bio-oil increased due to deoxygenation. The aromatic compound and heating value was increased when catalytic pyrolysis was applied.u

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.666-668
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• 2007

에너지 사용량의 증가와 국제적인 환경 규제에 대응하기 위하여 환경친화적인 연료의 개발이 시급한 가운데 재생가능한 동식물성 유지로부터 생산되는 바이오 디젤에 대한 연구가 활발히 진행되고 있다. 특히 자원 재활용 및 에너지 생산관점에서 폐식용유로부터 바이오디젤 원료로 사용하는 연구가 활발히 진행되어 왔다. 이러한 폐식용유를 이용한 바이오디젤 생산에서 폐식용유내 함유된 유리지방산 및 수분에 의해 효율적인 전이에스테르화 반응이 어렵기 때문에 이를 전처리 단계에서 제거되어야 한다. 본 연구에서는 폐식용유내 유리지방산을 효과적으로 제거하기 위하여 회분식 반응기에서 MFI 제올라이트 촉매를 이용하여 Si/Al 몰비에 따른 산세기 및 산량의 변화에 따른 유리지방산 제거 특성을 조사해 보았다.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.679-684
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• 2017

The influence of catalytic activity on Fe loading methods over Fe/BEA zeolite catalyst in the simultaneous reduction of $N_2O/NO$ has been studied. The Fe/BEA zeolite catalysts were prepared by ion exchange and impregnation. Catalytic tests were carried out in the selective catalytic reduction using ammonia as a reductant to identify the activity of prepared catalysts. The results show that the ion exchanged catalyst exhibited higher NO and $N_2O$ conversions than the impregnated catalysts did. To investigate the difference in catalytic activity, we performed various analyses such as XRD, $H_2-TPR$, $O_2-TPD$ and XPS. It is considered that the increase in the activity of the ion exchange catalyst is due to improved reducibility and increased oxygen desorption rate. In addition, the ion exchange catalyst was found through the XPS analysis that $Fe^{2+}$, which is related to the catalytic activity, is formed about 1.6 times more than the impregnated catalyst.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.110-110
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• 2003

제올라이트는 다양한 유기질 분리의 촉매제 및 광학, 화학 센서, 기체 분리 등의 고기능 소재로서 크게 주목받고 있으며, 그 중 MFI type(ZSM-5, Silicalite-1) 제올라이트는 주로 석유화학공정에 주로 이용되고 있고, 분리막으로서 이산화탄소의 분리/회수 및 물/유기 혼합물의 분리 등에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 분리막 제조에 유리할 것으로 판단되어지는 적합한 크기와 형상을 갖춘 나노크기의 제올라이트 분말을 수열합성법과 마이크로웨이브 합성법을 이용하여 합성하였으며, 위의 조건으로 다공질 알루미나 지지 체 위에서 알루미나/제올라이트 분리막 제조를 하는데 성공하였다. 또 한 다양한 조건(시간, 온도, 조성)에 따른 막의 두께변화와 균열발생정도를 관찰한 결과 합성시간, 건조온도에 따라서 같은 조건의 분리막 사이에서도 현격한 차이가 나타남을 알 수 있었다. 얻어진 MFI type제올라이트 분말과 분리막은 XRD, SEM, BET, TGA, FT-IR등의 분석수단을 이용하여 물성평가를 실시하였다.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.33-35
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• 2012

본 연구에서는 전이금속 Cu, Mn이 함침된 제올라이트를 사용하여 일산화탄소의 흡착능을 연구하였다. 금속 복합 산화물촉매 제조는 Cu, Mn을 서로 다른 비율로 물리 혼합하여 지지체에 담지하였다. 제올라이트 분자체는 상용 13X를 사용하였다. 함침방법은 과잉용액 함침법을 사용하였고, 건조 후 소성 하여 산화물 형태로 담지하였다. 합성된 개질 흡착제의 표면특성 분석은 $N_2$흡착 및 탈착곡선을 통한 질소흡착 특성 분석으로 기공크기, 기공분포, 비표면적을 구하였으며, FT-IR, X-선 회절분석, 전자주사현미경, $NH_3$-TPD/TPR 으로 특성을 분석하였다. 흡착 실험은 고정층 반응기에서 수행하였으며, 내경 4 mm 석영관에 흡착제를 충진하고 흡착파과곡선을 Gas Chromatograph로 측정하여 Cu-Mn 제올라이트 촉매의 일산화탄소 흡착 성능을 연구하였다. Cu-Mn 함량 비율과 흡착조업조건에 따른 흡착능을 측정하여 최적 흡착조건을 구하였다.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.97-102
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• 1981

The conversion of methanol to hydrocarbons has been studied over synthetic ZSM-5 zeolite catalyst having high silica to alumina ratio. The conversion products were olefins, paraffins, cycloparaffins, and aromatics, and the catalyst showed especially high selectivity toward the formation of aromatics. The catalyst showed the shape-selectivity and the size of molecules in the product was limited approximately to the size of 1,3,5-trimethylbenzene. Hydrogen form(HZSM-5) was more active, indicating reactions following the dehydration of methanol seemed to be mainly catalyzed by acid sites. Comparison of the reaction characteristics and acid site distribution of the ZSM-5 catalyst with those of mordenite and faujasite type catalysts suggests that cross-linked pore channel structure and the strong acidity of the ZSM-5 catalyst are primarily responsible for the selective formation of aromatics over this catalyst.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.547-553
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• 2007

The catalytic cracking of n-octane over FER, MFI, MOR and BEA zeolites was studied by the protolytic cracking mechanism in order to understand the effect of pore structure of zeolites on their product composition and deactivation. The selectivities for $C_3$ and $C_3{^=}$ were high over the zeolites with medium pores due to additional cracking, while those for $C_4$ and $C_4{^=}$, the initial products, were high over the zeolites with large pores. MFI zeolite showed slow deactivation due to small carbon deposit, while FER zeolite with small pores deactivated rapidly with severe carbon deposit. The deactivation of BEA zeolite was slow even with a large amount of carbon deposit, but MOR zeolite showed a rapid deactivation even with a small amount of carbon deposit. The conversion measured along with the time on stream on these zeolite catalysts was simulated by a mechanism based on the simplified reaction path of n-octane cracking and the deactivation related to the pore blockage by carbon deposit.