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        검색결과 5

        1.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbon spheres (ACS) were prepared at different heating rates by carbonization of the resole-type phenolic beads (PB) at 950℃ in N2 atmosphere followed by activation of the resultant char at different temperatures for 5 h in CO2 atmosphere. Influence of heating rate on porosity and temperature on carbon structure and porosity of ACS were investigated. Effect of heating rate and temperature on porosity of ACS was also studied from adsorption isotherms of nitrogen at 77 K using BET method. The results revealed that ACS have exhibited a BET surface area and pore volume greater than 2260 m2/g and 1.63 cm3/g respectively. The structural characteristics variation of ACS with different temperature was studied using Raman spectroscopy. The results exhibited that amount of disorganized carbon affects both the pore structure and adsorption properties of ACS. ACS were also evaluated for structural information using Fourier Transform Infrared (FTIR) Spectroscopy. ACS were evaluated for chemical composition using CHNS analysis. The ACS prepared different temperatures became more carbonaceous material compared to carbonized material. ACS have possessed well-developed pores structure which were verified by Scanning Electron Microscopy (SEM). SEM micrographs also exhibited that ACS have possessed well-developed micro- and meso-pores structure and the pore size of ACS increased with increasing activation temperature.
        4,000원
        2.
        2007.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Molecular sieving carbon (MSC) for separating O2-N2 and CO2-CH4 has been prepared through chemical vapor deposition (CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity of the material for assessment of molecular sieving behavior for O2-N2 and CO2-CH4 pair of gases was assessed by the kinetic adsorption of the corresponding gases at 25℃. It was observed that methane cracking on ACS lead to deposition of carbon mostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showing good selectivity for CO2-CH4 and O2-N2 separation was obtained through benzene cracking on ACS with benzene entrantment of 0.40×10-4 g/ml at cracking temperature of 725℃ for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for O2-N2 and 8.00:1.00 for CO2-CH4 pair of gases respectively.
        4,000원
        3.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        It is well established that halogenated fullerene derivatives act as synthetic intermediates for further substitution viareplacement with nucleophlies. In the present work, systematic studies were carried out on the synthesis of bromofullerenesunder different experimental conditions. The effect of reaction time on the product formed was observed. We observed theformation of new compound of bromofullerenes in a different stoichiometric ratio i.e., C60Br14; in addition to previousreported bromofullerenes in the stoichiometric ratio of C60Br6, C60Br8, and C60Br24. The new derivative of bromofullerene wasisolated and well characterized by various analytical techniques like FT-IR, TGA, DSC, and elemental analysis. In this paper,detail of the synthesis and characterization of the bromofullerene prepared are described. The yields obtained were better thanthose reported previously.
        4,000원
        4.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Granular Activated Carbon (GAC) has been proven to be an excellent material for many industrial applications. A systematic study has been carried out of the kinetics of physical as well as chemical activation of phenolic resin chars. Physical activation was carried out using CO2 and chemical activation using KOH as activating agent. There are number of factors which influence the rate of activation. The activation temperature and residence time at HTT varied in the range 550~1000℃ and ½~8 hrs respectively. Kinetic studies show that the rate of chemical activation is 10 times faster than physical activation even at much lower temperature. Above study show that the chemical activation process is suitable to prepare granular activated carbon with very high surface area i.e. 2895 m2/g in short duration of time i.e. 1 to 2 hrs at lower temperature i.e. 750℃ from phenolic resins.
        4,000원
        5.
        2003.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In polymer precursor based activated carbon, the structure of starting material is likely to have profound effect on the surface properties of end product. To investigate this aspect phenolic resins of different types were prepared using phenol, mcresol and formaldehyde as reactants and Et3N and NH4OH as catalyst. Out of these resins two resol resins PFR1 and CFR1 (prepared in excess of formaldehyde using Et3N as catalyst in the basic pH range) were used as raw materials for the preparation of activated carbons by both chemical and physical activation methods. In chemical activation process both the resins gave activated carbons with high surface areas i.e. 2384 and 2895 m2/g, but pore size distribution in PFR1 resin calculated from Horvath-Kawazoe method, contributes mainly in micropore range i.e. 84.1~88.7 volume percent of pores was covered by micropores. Whereas CFR1 resin when activated with KOH for 2h time, a considerable amount (32.8%) of mesopores was introduced in activated carbon prepared. Physical activation with CO2 leads to the formation of activated carbon with a wide range of surface area (503~1119 m2/g) with both of these resins. The maximum pore volume percentage was obtained in 3-20 a region by physical activation method.
        4,000원