• Bulletin of the Korean Chemical Society
• /
• 제33권11호
• /
• pp.3749-3754
• /
• 2012

Nanoporous carbons with a high specific surface area were prepared directly from thermoplastic acrylic resin as carbon precursor and MgO powder as template by carbonization over the temperature range, $500-1000^{\circ}C$. The effect of the carbonization temperature on the pore structure and $CO_2$ adsorption capacity of the obtained porous carbon was examined. The textural properties and morphology of the porous carbon materials were analyzed by $N_2/-196^{\circ}C$ and $CO_2/0^{\circ}C$ adsorption/desorption isotherms, SEM and TEM. The $CO_2$ adsorption capacity of the prepared porous carbon was measured at $25^{\circ}C$ and 1 bar and 30 bar. The specific surface area increased from 237 to $1251m^2/g$, and the total pore volumes increased from 0.242 to $0.763cm^3/g$ with increasing the carbonization temperature. The carbonization temperature acts mainly by generating large narrow micropores and mesopores with an average pore size dependent on the level of carbonization of the MgO-templated nanoporous carbons. The results showed that the MgO-templated nanoporous carbons at $900^{\circ}C$ exhibited the best $CO_2$ adsorption value of 194 mg/g at 1 bar.

• 멤브레인
• /
• 제17권4호
• /
• pp.329-337
• /
• 2007

본 연구에서는 p-toluenesulfonic acid (TSA)와 polyvinylpyrrolidone (PVP)를 함유한 polyethersulfone (PES) 고분자 용액을 이용하여 PES 멤브레인 내에 최소 공경을 갖는 내부 분리층을 만드는 방법에 관한 새로운 방법을 제시하고자 한다. 팽윤제로 사용된 PVP와 응고제로 사용된 TSA를 함유한 평막형 PES 멤브레인의 제조 및 구조적인 특성 조사가 수행되었으며, 상업용 막에 대등할 만한 투과 성능과 좁은 pore size distribution을 가지는 멤브레인을 제조할 수 있음을 확인하였다. 또한 PVP의 첨가는 멤브레인의 단면구조와 투과 성능에, TSA는 투과 성능보다는 pore size distribution에 영향을 준다는 것을 확인하였으며 이는 FE-SEM 결과와 TSA를 첨가한 멤브레인의 단면 사진에서 내부 최소 기공층의 두께가 두꺼워짐을 확인할 수 있었다.

• 한국진공학회지
• /
• 제2권4호
• /
• pp.491-500
• /
• 1993

The adsorption of nitrogen (77K) and carbon dioxide(273K) was performed on a series of activated carbon fiber. Theadsorption iotherm of nitrogen was typical type 1 and that of carbon dioxide was convex. As the specific surface area increases, there are linear increases in BET constant C mean pore diameter, the width of pore size distribution, wide micropore volume, total micropore volume, total pore volume and external surface area, however, narrow micropore volume was nealy constant . The total micorpore volume fraction in total pore volume is above 97%.

• 한국세라믹학회지
• /
• 제32권2호
• /
• pp.209-216
• /
• 1995

In order to investigate the effect o green microstructure on the sintering behavior and properties of AlN ceramics, samples were prepared by slip casting and dry pressing. The slip cast samples had high green density, fine pore size and narrow pore size distribution. They showed much higher sinterability and more homogeneous sintered microstructure compared to the dry pressed samples. Both increased thermal conductivity and flexural strength for samples prepared by slip casting could be attributed to the improved microstructural homogeneity with isolated second phase(s).

• Carbon letters
• /
• 제8권1호
• /
• pp.17-24
• /
• 2007

Microporous carbons with narrow pore size distribution have been successfully synthesized by using hydrolyzed and calcined silica as templates and phenol formaldehyde (pf) resin as carbon precursor. Phenol formaldehyde-silica micro composites were prepared by solution route. Subsesequently, silica templates were removed by HF leaching. Resulting carbons were steam activated. The porous carbons were characterized by nitrogen adsorption-desorption isotherm, SEM, FTIR analysis, iodine adsorption, thermogravimetry analysis, etc. Adsorption isotherms show that the porous carbon prepared from calcined silica as templates are microporous with 88% pores of size <2 nm porosity and are of type I isotherm, while porous carbon prepared by using hydrolyzed silica are microporous with 89% microporosity, shows hysteresis loop at high relative pressure indicating the presence of some mesoporosity in samples. The microporosity in porous carbon materials has a bearing on the nature of silica templates used for pore formation.

• 한국재료학회지
• /
• 제9권4호
• /
• pp.362-367
• /
• 1999

We intended to make the activated carbon fibers which could separate, remove and recover the volatile organic compounds of benzene, toluene, acetone and methanol. Changing activation temperature and time, large specific surface area and narrow pore distribution could be obtained. The activated carbon fibers have large adsorption capacity and selectivility for those organic compounds. We characterized the adsorption capability of the activated carbon fibers for benzene, toluene, acetone and methanol by BET specific surface area and pore size and micropore volume measurements. In the result of activation, the maximum value of BET specific surface area of the fibers was $1100\m^2$/g at $800^{\circ}C$ for 60 minutes and $K_2$O was reduced actively in this condition. Their average pore size was 5.8~5.9$\AA$. The activated carbon fibers prepared in this work had high adsorption rate to saturation and the selectibility for the above organic compounds. The adsorbed amount of acetone and methanol(diameter of$ 4.3\AA$ and $4.4\AA$ respectively) which are smaller than micropore diameter in size was 43~49%, which was larger value than benzene and toluene(in the same diameter as $5.9\AA$).

• 한국세라믹학회지
• /
• 제34권4호
• /
• pp.343-350
• /
• 1997

To fabricate the ceramic/metal(SiC/ Al alloy) composite, SiC preform was prepared by Pressureless Powder Packing Forming Method and 6061 Al alloy was infiltrated into the preform. Uniform compact having an average pore size of 10 ${\mu}{\textrm}{m}$ and narrow pore size distribution was prepared. Phenolic resin solution(40 wt%) was penetrated into the SiC compact, and then the compact was preheated at the temperature of 120$0^{\circ}C$. The pore size distribution and the microstructure of the preform were not changed by preheating. An uniform microstructure without any crack in the preform was obtained in SiC-Al alloy composite. The infiltration of 6061. Al alloy into the preform began at the temperature of 130$0^{\circ}C$ and the amount of infiltration increased in proportion to the infiltration temperature and the soaking time. The increasement rate of the infiltration amount decreased after 3 h. As a result of the infiltration at 140$0^{\circ}C$ for 4 h, Al alloy was well distributed in the interparticle channels and the relative density of the composite was above 98%. The strength and the fracture toughness of the composite were 303 MPa and 21.65 MPam1/2, respectively.

• 한국세라믹학회지
• /
• 제32권1호
• /
• pp.113-119
• /
• 1995

The green body was fabricated by a new forming method, pressureless powder packaing forming method, and the characteristics of sintered specimen were investigated. It was found that alumina ceramics prepared by the present method showed porous structure with narrow pore size distribution, and in case of abrasive powder sintered body, compared with dry-pressed specimen, had the nearly same density. Especially, the specimen prepared with spray-dried granules showed the characteristic that granules were not either deformed or fractured during forming and sintering process. Therefore, it was found that this new forming method was effective method in fabrication of porous ceramics on account of easy control of porosity and pore size and its high thermal stability.

• Bulletin of the Korean Chemical Society
• /
• 제26권7호
• /
• pp.1075-1078
• /
• 2005

Hydrogen adsorption on various porous materials have been studied with a volumetric method at low temperature in the pressure of 0-760 torr. Their hydrogen uptakes depend at least partly on microporosity rather than total porosity. However, it is also necessary to consider other parameters such as pore size and pore architecture to explain the adsorption capacity. The heat of adsorption and adsorption-desorption-readsorption experiments show that the hydrogen adsorption over the porous materials are composed of physisorption with negligible contribution of chemisorption. Among the porous materials studied in this work, SAPO-34 has the highest adsorption capacity of 160 mL/g at 77 K and 1 atm probably due to high micropore surface area, micropore volume and narrow pore diameter.

• 한국세라믹학회지
• /
• 제40권7호
• /
• pp.677-682
• /
• 2003

석탄회.점토의 무게비가 7 : 3인 슬립에 대하여 그 해교정도에 따라 slip을 F(Flocculated), M(Moderate) 및 D(Dispersed)의 3종류로 제조하고 이로부터 소결체를 합성하여 시편의 물성과 슬립 특성과의 관계를 분석하였다. Slip F는 응집입자의 크기분포가 넓은 반면 slip D는 입도분포가 좁고 11 $\mu\textrm{m}$ 이상의 큰 응집입자가 거의 존재하지 않았다. 성형체의 기공은 슬립의 종류에 관계없이 1~4 $\mu\textrm{m}$ 범위 내에 분포하며 소결 후에는 1 $\mu\textrm{m}$ 이하의 미세기공은 거의 소멸된 반면, 큰 기공은 1 $\mu\textrm{m}$ 정도 더 성장하였다. Slip F의 경우에 소결 후 기공분포는 slip M과 D에 비하여 주피크의 높이가 높고 폭이 좁았으며, large pore limit (가장 큰 기공 크기)가 5.1 $\mu\textrm{m}$로 다른 슬립 성형체보다 작았다. 입자가 잘 분산된 슬립(slip D)보다는 약간 응집된 슬립(slip F)이 소결시 시편내 거대기공의 생성을 억제함으로서 높은 압축강도를 얻는데 유리하였다. 이상의 결과로부터 소결체의 기계적 특성은 기공분포에 크게 의존하며, 이는 슬립의 분산특성을 제어함으로서 가능함을 알 수 있다.