Extraction of coal tar pitch using a mixture of compressed CO{sub 2} and toluene
- Univ. of Kentucky, Lexington, KY (United States)
The removal of low-molecular-weight components from commercial pitches is a critical step in the production of suitable precursors for isotropic carbon fiber formation. A unique extraction process employing a one-phase binary mixture of carbon dioxide and toluene has been developed to remove low-molecular-weight components from coal tar pitch, with an ultimate goal of increasing the softening point of the pitch. The mass fraction of coal tar pitch extracted was determined as a function of extraction temperature (25--75 C), pressure (8.7--14.9 MPa), and extractive solvent composition (40--70 wt % toluene) using a factorial experimental design. As much as 44 wt % of the coal tar pitch was removed at these extraction conditions, and softening points greater than 250 C were achieved. The separation is controlled by the temperature and composition of the extractant solvent. This compressed gas/organic solvent extraction process removes low-molecular-weight material from the coal tar pitch using significantly milder solvents and reduced temperatures relative to traditional extractive processes.
- OSTI ID:
- 697170
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 38, Issue 9; Other Information: PBD: Sep 1999
- Country of Publication:
- United States
- Language:
- English
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