• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2748-2752
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• 2012

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and $H_2O_2$ as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-acetylacetonate complexes are stable under the present reaction conditions.

• 한국입자에어로졸학회지
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• 제11권3호
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• pp.87-92
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• 2015

MCM-41 (Mobil Composition of Matter) and SBA-15 (Santa Barbara Amorphous) were used as a supported catalyst for ethylene polymerization due to their combination of large surface area and wide range of pore size distribution. The morphology of supports was used to control the morphology of the resulting polymer. Different molar ratios of Al/Ti were used for ethylene polymerization at $60^{\circ}C$ under atmospheric pressure. The effect of different mass ratios of MCM-41/SBA-15 and 1-hexene concentration on polymerization activity and polymer properties was investigated. The catalytic activity and the crystallinity reached the highest value at Al/Ti of 480. Upon incorporation of MCM-41 and SBA-15 into $MgCl_2/TiCl_4$ catalyst, the molecular weight and crystallinity of polyethylene were enhanced. The obtained polyethylene showed melting temperature between 130 and $135^{\circ}C$. The polyethylene with replication structure of support and bimodal MWD was expected.

• 대한화학회지
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• 제44권1호
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• pp.52-59
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• 2000

(0.3${\sim}$2.1) $SiO_2:\;(0.10{\sim}0.50)\;CTABr:\;0.15{\sim}0.23)\;TMAOH:\;(20{\sim}100)\;H_2O$의 비를 가진 겔 혼합물을 실온에서 정한 시간 동안 숙성시킨 다음, $150^{\circ}C$ 에서 48시간 동안 수열 반응시킨다. 합성과정에서 측정된 pH는 TMAOH와 실리카의 농도에 따라 변화되었으며, pH의 변화는 생성물의 상에 영향을 주었다. 생성물의 상은 X-선 회절기로 측정되었다. 0.19에서 0.23 범위에서 TMAOH 비율이 증가함에 따라, 겔의 염기성이 증가하고, 생성물 내 판상이 증가한다. TMAOH의 비가 0.19 이하에서는 pH가 감소하면서 육각상이 감소한다. $SiO_2$의 농도가 낮은 경우, 판상의 양이 증가하고, 높은 농도에서는 과다한 실리카원으로 인하여 MCM-41의 결정성이 저하된다. 결정성이 가장 우수한 MCM-41이 합성된 혼합물의 농도비는 $1.0\;SiO_2:\;0.27\;CTABr:\;0.19\;TMAOH:\;40\;H_2O$이었으며, 이 겔의 초기 pH와 24시간 동안 숙성 후의 pH와 $150^{\circ}C$에서 2일간 반응 후의 pH는 각각 12.3, 1 1.5, 10.5였다. MCM-41의 결정성을 높히기 위해서는 숙성이 필수적이며 하루 정도의 숙성이 가장 적당하였다. 하루 이상의 숙성은 육각상의 비율을 감소시킨다.

• 한국자기공명학회논문지
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• 제3권2호
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• pp.109-126
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• 1999

The location of Cu(II) exchanged into measoporous aluminosilicate MCM-41(AlMCM-41) material and its interaction with various adsorbate molecules were investigated by electron spin resonance and electron spin echo modulation spectroscopies. Cu(II) is fully coordinated to adsorbates in a wide open mesopore of AlMCM-41 for the formation of favorable complexes. It was found that in the fresh hydrated material, Cu(II) is octahedrally coordinated to six water molecules as evidenced by an isotropic room temperature ESR signal. This species is located in a cylindrical MCM-41 channel and rotates rapidly at room temperature. Evacuation at room temperature removes some of these water molecules, leaving the Cu(II) coordinated to less water molecules and anchored to oxygens in an MCM-41 channel wall. Dehydration at 450$^{\circ}C$ produces one Cu(II) species located on the internal wall of a channel, which is easily accessible to adsorbates. Adsorption of adsorbate molecules such as water, methanol, ammonia, pyridine, aniline, acetonitrile, benzene, and ethylene on a dehydrated Cu-AlMCM-41 material causes changes in the ESR spectrum of Cu(II), indicating the complex formation with these adsorbates. Cu(II) forms a complex with six molecules of methanol as evidenced by an isotropic room temperature ESR signal and ESEM analysis like upon water adsorption. Cu(II) also forms a square planar complex containing four molecules of N-containing adsorbates such as ammonia, pyridine and aniline based on resolved nitrogen superhyperfine interaction and their ESR parameters. However, Cu(II) forms a complex with six-molecules of acetonitrile based on ESR parameters. Only one molecule of benzene or ethylene is coordinated to Cu(II).

• 한국응용과학기술학회지
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• 제21권4호
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• pp.345-351
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• 2004

Highly ordered pure-silica MCM-41 materials possessing well-defined morphology have been successfully prepared with surfactant used as a template. The fabrication of mesoporous silica has received considerable attention due to the need to develop more efficient materials' for catalysis, separations, and chemical sensing. The surface modified MCM-41 was used as anadsorbent for biomolecules. Silica-supported organic groups and DNA adsorption on surface modified MCM-41 were investigated by FT-IR and UV-Vis spectrometer, respectively. The use of MCM-41 as the modification of electrode surfaces were investigated electrochemical properties of metal mediators with biomolecules. The modified ITO electrodes increased peak currents for a redox process of $[Ru(bpy)_3]^{2+}$ relative to the bare electrode. The electrochemical detection of DNA by cyclic voltammetry when the current is saturated in the presence of the mediator appeared more sensitive due to a higher catalytic current on the MCM-41 supported electrodes modified by carboxylic acid functional groups. The carboxyl or amine groups on the surface of MCM-41 interact and react with the $-NH_2$ groups of guanine and backbone, respectively. Highly ordered mesoporous materials with organic groups could find applications as DNA sensors.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 추계 기술심포지움 논문집
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• pp.61-64
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• 2000

IMT 2000 단말기용 2.14 GHz 대역의 저잡음 증폭기 (Low Noise Amplifier, LNA)를 MCM-C 기술을 이용하여 제작하고 그 특성을 측정하였다. 먼저 저잡음 증폭기 회로를 설계한 후, 각 소자들의 고주파 library를 이용한 회로 시뮬레이션으로과 특성을 확인하였다. 시뮬레이션 상에서 이득(Gain)은 17 dB 였으며, 잡음지수 (Noise Figure)는 1.4 dB 였다. MCM-C 저잡음 증폭기는 LTCC 기판과 전극 및 저항체의 동시소성에 의해 코일(L), 콘덴서(C), 저항(R)을 기판 내부에 넣었으며, 마이크로 스트립 라인과 SMD 부품의 실장을 위한 Pad를 최상부에 제작하였다. 기판은 총 6 층으로 구성하였으며, 내부에 포함된 수동소자는 코일 2개, 콘덴서 2개, 저항 3개 등 총 7 개 였다. 시작품의 특성 측정 결과, 2.14 GHz에서 이득은 14.7 dB 였으며, 잡음지수는 1.5 dB 정도의 값을 가졌다.

• 대한전자공학회논문지TC
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• 제47권3호
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• pp.31-38
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• 2010

본 논문에서는 MIMO-OFDM 시스템에 여러 MIMO 기법을 적용한 후 모의실험을 통하여 성능을 비교 및 분석하였고, 또한 Pre-coding, Antenna Subset Selection, AMC 기법을 적용하여 시스템을 분석하였다. 그리고 최종적으로 제안한 Adaptive-MCM(Adaptive-MIMO-Coding-Modulation) 기법의 성능을 분석하였다. 그 결과 4세대 이동통신 시스템에서 요구되고 있는 최대 전송률과 고품질 서비스의 Trade-off 관계를 개선할 수 있음을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.70-75
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• 1997

A wide range (10 < Si/V) of mesoporous vanadium silicate molecular sieves with the MCM-41 structure have been synthesized using vanadyl sulfate as the source of vanadium and characterized by XRD, 51V MAS NMR and 29Si MAS NMR. The increase of the unit cell parameter and the decrease of Q3/Q4 ratio of 29Si spectra with the vanadium content suggest the incorporation of vanadium in the framework of MCM-41 structure. 51V MAS NMR demonstrates that vanadiums in as-synthesized V-MCM-41 are present in the chemical environment of octahedra and octahedral vanadium is decreased and tetrahedral vanadium is increased inversely with raising the calcination temperature. Though the thermal treatment in rotor of hydrated sample resulted in the change from tetrahedral environment to octahedral one and the steaming and the acid treatment affect to the chemical environment of vanadium, the spectrum similar to originally calcined sample is regenerated after recalcination. This indicates that the vanadium is belong to the framework in a relatively exposed site. The best quality XRD pattern of the product of Si/V=27 may be attributable to heterogeneous nucleation mechanism. V-MCM-41's having the Si/V ratio lower than 20 are completely collapsed after calcination.

• 공업화학
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• 제27권2호
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• pp.190-194
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• 2016

Tricyclopentadiene (TCPD)는 차세대 고밀도에너지 연료인 tetrahydrotricyclopentadiene의 전구체로서 중요한 화합물이다. 본 연구에서는 이온성 액체가 담지된 메조포로스 실리카 촉매를 이용하여 dicyclopentadiene 소중합 반응을 통한 TCPD 합성에 관한 연구를 수행하였다. 나노기공의 크기가 다른 대표적인 메조포로스 실리카인 MCM-41과 SBA-15에 이온성 액체(IL)를 함침법을 이용하여 담지하고 소중합 촉매를 제조하였다. 음이온 전구체로 copper(I) chloride (CuCl) 또는 iron(III) chloride ($FeCl_3$), 양이온 전구체로 triethylamine hydrochloride (TEAC) 또는 1-butyl-3-methylimidazolium chloride(BMIC)를 사용하여 4가지 종류의 IL을 메조포로스 실리카에 담지하였다. 이온성 액체가 담지된 메조기공의 실리카를 사용하였을 때 이온성 액체만 사용하였을 때보다 TCPD 수율과 dicyclopentadiene (DCPD)의 전환율 측면에서 우수하였다. 특히, MCM-41에 루이스 산도가 낮은 CuCl계 이온성 액체를 담지할 때 TCPD 수율이 가장 높았다.

• 대한화학회지
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• 제55권3호
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• pp.430-435
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• 2011

화력발전소에서 배출되는 석탄회를 이용하여 메조다공성 소재인 MCM-41을 제조하였다. 제조한 소재는 XRD, FTIR, SEM 및 EDS 방법으로 특성을 규명하였다. 이 소재의 촉매활성을 방향족 알데히드와 malonontrile의 Knoevenagel축합 반응에서 5-arylindene malononitriles의 합성에 대해 연구하였다. 이 방법의 특징은 쉬운 취급법, 안정성, 촉매의 재사용 및 생태친화성, 고수율, 짧은 반응시간, 간단한 실험과정 및 마무리 절차 등을 들 수 있다.