Synthesis of Fullerenes from a Nonaromatic Chloroform through a Newly Developed Ultrahigh-Temperature Flash Vacuum Pyrolysis Apparatus

Abstract

The flash vacuum pyrolysis (FVP) technique is useful for preparing curved polycyclic aromatic compounds (PAHs) and caged nanocarbon molecules, such as the well-known corannulene and fullerene C₆₀. However, the operating temperature of the traditional FVP apparatus is limited to ~1250 °C, which is not sufficient to overcome the high energy barriers of some reactions. Herein, we report an ultrahigh-temperature FVP (UT-FVP) apparatus with a controllable operating temperature of up to 2500 °C to synthesize fullerene C₆₀ from a nonaromatic single carbon reactant, i.e., chloroform, at 1350 °C or above. Fullerene C₆₀ cannot be obtained from CHCl₃ using the traditional FVP apparatus because of the limitation of the reaction temperature. The significant improvements in the UT-FVP apparatus, compared to the traditional FVP apparatus, were the replacement of the quartz tube with a graphite tube and the direct heating of the graphite tube by impedance heating instead of indirect heating of the quartz tube using an electric furnace. Because of the higher temperature range, UT-FVP can not only synthesize fullerene C₆₀ from single carbon nonaromatic reactants but sublimate some high-molecular-weight compounds to synthesize larger curved PAHs in the future.

Keywords: flash vacuum pyrolysis; fullerenes; nanocarbon; pyrolysis apparatus.

Figure 1

Schematic of the newly developed ultrahigh-temperature flash vacuum pyrolysis (UT-FVP) apparatus.

Figure 2

HPLC-UV (330 nm) chromatogram of the product from the pyrolysis of CHCl₃ at the temperature range of ~960–1800 °C.

Figure 3

HPLC-MS chromatogram of the soot products from the pyrolysis of CHCl₃ at 1530 °C.

Figure 4

(a) HPLC-MS chromatogram of soot products from the pyrolysis of ¹³CHCl₃ at 1740 °C. Peaks are labeled by numbers, and their molecular formulae are suggested from their isotope distributions in mass spectra: (1) ¹³C₁₀Cl₈; (2) ¹³C₆Cl₅O; (3) ¹³C₁₂Cl₉O; (4) ¹³C₁₂Cl₈; (5) ¹³C₁₀Cl₇O; (6) ¹³C₁₄Cl₁₀; (7) impurity; (8) ¹³C₁₂Cl₈; (9) ¹³C₁₄Cl₉O; (10) ¹³C₁₈Cl₁₂; (11) ¹³C₁₆Cl₁₀; (12) ¹³C₁₈Cl₁₀; (13) ¹³C₂₂Cl₁₂; (14) ¹³C₂₄Cl₁₂; and (15) ¹³C_60. (b) The experimental and theoretically simulated mass spectra of ¹³C₁₄Cl₁₀ and ¹³C₆₀ (¹³C = 99%).