Separation of Fullerenes by Sublimation. Tomoaki SASAKI and Katsumitsu NAKAMURA

Transcription

1 No pp Separation of Fullerenes by Sublimation Tomoaki SASAKI and Katsumitsu NAKAMURA Received September 30, 2006 Separation of fullerenes by utilizing differences in the vapor pressure has been studied as one approach to the purification of fullerenes. This separation method depends on knowledge of the temperature dependence of the vapor pressure of fullerenes as the associated heat of sublimation. A raw soot is inserted in an evacuated quartz tube ( Torr), and then it is heated over the temperature range to sublime the fullerenes, which then condense at a temperature gradient ( ) parts in the tube. It has been found that the efficiency of separation at the low and high temperature fractions are satisfactory, however, the quantities of the fraction are slightly. It is considered that sublimation method is effective as the method of separating for higher fullerenes. However, separation ability in one process is very small, therefore, efficient separation of the fullerenes will be possible by the multiple steps of the sublimation and condensation processes. Keywords : fullerene, C 60, C 70, vapor pressure, sublimation, separation Kroto Smalley 1 C Kraetschmer Huffman C 60 C C NMR C 60 3 C 70 4 C 76 5 C 84 6 HPLC Cox 7 Yeretzian 8 Averitt 9 10 : Department of Chemistry, College of Humanities and Sciences, Nihon University: Sakurajosui Setagaya ku, Tokyo, Japan 229 9

2 Table 1 C Torr , 4 Temperature / Table 1 Vapor pressure of some fullerenes C 60 3 Vapor pressure / Torr C 70 4 C 76 5 C obtained by extrapolations 30 mm 10 cm 750 W SCR 20 mm 70 cm mm 100 cm 10 cm 100 cm Fig.1 Fig.2 30 mm 20 cm 1200 W SCR Fig. 2 Temperature gradient of sublimation system. The zero indicate the bottom of the sublimation tube. The position 20 cm is contact point of the sublimation tube and the deposition tube. Fig. 1 Apparatus for fullerenes separation by sublimation

3 10 12 mm 20 cm mm cm mm 75 cm Torr 2. 2 MER Corporation 7 MER Corporation mg Torr Torr Torr 22 cm ml HPLC /min /min /min /min /min /min HPLC HPLC n ODS DOCOSIL mm Fig. 3 Typical chromatogram for the separation of fullerenes 150 mm C 60 C nm C 60 C 70 C 76 C 78 C 82 C 84 C ml/min 308 nm Fig.3 Table 2 C 82 C 84 Table 2 Retention Time and Total Ratio of Fullerenes in Sample Carbon Soot C 60 C 70 C 76 C 78 C 82 + C 84 C 86 R.T / min Ratio / HPLC Fig /

4 Fig. 4 Quantitative ratio of deposits with solid line and ratio of each fullerenes with dotted line, C 60 ; with dashed line, C 70 ; with dotted line, C 76 ; with dotted line, C 78 ; with dotted and dashed line, C 82 C 84 ; with dashed line, C 86 as a function of deposition zone in the case of carbon soot used. The soot heated at 900 for 60 min. Fig. 6 Quantitative ratio of deposits and ratio of each fullerenes as a function of temperature of deposition zone. The symbols and lines in the figure are the same as Fig.4. The soot heated from 500 up to 900 at constant rate heating of 3.3 /min. Fig. 5 Quantitative ratio of deposits and ratio of each fullerenes as a function of temperature of deposition zone. The symbols and lines in the figure are the same as Fig.4. The soot heated at 900 for 960 min. Fig. 7 Quantitative ratio of deposits and ratio of each fullerenes as a function of temperature of deposition zone. The symbols and lines in the figure are the same as Fig.4. The soot heated from 500 up to 900 at constant rate heating of 0.14 /min. 350 C 60 C C 82 C C C C 76 C 78 1 C 82 C Fig C C C 60 C C 70 C 76 C 78, C 82 C C C 82 C

5 2 Fig.6 Fig C 60 C C 82 C 84, 18 C 70, 12 C 78, 8 C 60 2 C C C 82 C Fig.8 C 60 C Fig.9 60 Fig.10 Fig. 9 Quantitative ratio distribution of each fullerenes as a function of deposition temperature in the case of sublimation temperature at min. The symbols and lines for each fullerenes are the same as Fig. 8. Fig. 8 Quantitative ratio distribution of each fullerenes as a function of deposition temperature in the case of sublimation temperature at min. with dotted line, C 60 ; with dashed line, C 70 ; with dotted line, C 76 ; with dotted line, C 78 ; with dotted and dashed line, C 82 C 84 ; with dashed line, C 86. Fig. 10 Peak temperatures of each fullerenes deposition as a function of heating time in the case of sublimation temperature at 900 The symbols and lines for each fullerenes are the same as Fig

6 900 C 86 C 76 C 86 C 76 Fig.9 C 86 C 60 C 86 C 60 C 60 C 60 C 86 C 60 C 86 C 60 C 86 C Fig.11 HPLC C 60 : 79 C 70 : 17 C 76 : 3.3 C 78 : 2.2 C 82 C 84 : 1.2 C 86 : C 60 : 28 C 70 : C 60 : 1 C 70 : 9.5 C 78 : 14.5 C 82 C 84 : 64 3 C 60 : 0 C 70 : 4.6 C 78 : 7.4 C 82 C 84 : 81 C 86 : 6.6 Fig Each fullerenes ratio in the deposits at 500 and more as a function of sublimation time in the case of sublimation temperature at min. The symbols and lines for each fullerenes are the same as Fig

7 1 H. W. Kroto, J. R. Heath, S. C. O Brien, R. F. Curll, and R. E. Smalley, Nature W. Kraetschmer, L. D. Lamb, K. Fostiropoulos, and D. R. Huffman, Nature V. Piacente, G. Gigli, P. Scardala, A. Giustini, and D. Ferro, J. Phys. Chem V. Piacente, G. Gigli, P. Scardala, A. Giustini, and G. Bardi, J. Phys. Chem B. Brunetti, G. Gigli, E. Giglio, V. Piacente, and P. Scardala. J. Phys. Chem. B V. Piacente, C. Palchetti, G. Gigli, and P. Scardala, J. Phys. Chem. A D. M. Cox, R. D. Sherwood, P. Tindall, K. M. Creegan, W. Anderson, and D. J. Martella, American Chemical Society, Sympo. Ser C. Yeretzan, J. B. Wiley, K. Holczer, T. Su, S. Nguyen, R. B. Kaner, and R. L. Wheten, J. Phys. Chem R. D. Averitt, J. M. Alford, and N. J. Halas, Appl. Phys. Lett

8