Yazar "Ceylan K." seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Characterization of dissolution products from two turkish lignites by 1H NMR, IR and GC techniques
    (1991) Ceylan K.
    Some structural features of the dissolution products from two Turkish lignites (Beypazari and Tuncbilek lignites) have been investigated with proton nuclear magnetic resonance and infra-red spectroscopies and gas chromatography. The results indicate that, in general, no substantial changes occur in the structural characteristics of the soluble products obtained from different extraction conditions. This is true especially for preasphaltene and asphaltene fractions. On the other hand, some structural differences were observed in the compositions of oil fractions, especially in the neutral fraction of oils from the different experimental conditions. The neutral oils from the low temperature and short time extractions are mainly consisted of alkylated aromatics and include a very small quantity of longer chain paraffins. Whereas, the oils from the extractions at high temperatures and longer times, include several long straight-chain paraffins (C15 - C32) with higher quantity. Hydrogen atmosphere is moderately effective for deoxygenation of the products. Dealkylation reactions for smaller molecules are insignificant but hydrogen atmosphere is relatively effective for the dealkylation of larger molecules. Higher temperature and longer extraction period accelerate the liquid phase pyrolysis. © 1991, Taylor & Francis Group, LLC. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Reaction Pathways during Coprocessing. Reaction of Illinois No. 6 and Wyodak Coals with Lloydminster and Hondo Residua under Mild Conditions
    (1991) Ceylan K.; Stock L.M.
    Illinois No. 6 and Wyodak coals were coprocessed with Lloydminster and Hondo residua. The reactions were carried out in argon or in dideuterium with and without a catalyst at 400 °C for 1 h. The coal conversions under these mild conditions ranged from 40 to 56 %. Wyodak coal and Lloydminster residuum provided the highest coal conversion in uncatalyzed reactions. Spectroscopic evidence indicated that coal fragments appeared in the oil fraction at short reaction times but that they were much more abundant in the asphaltene fraction. An analysis of the results implies that coprocessing is essentially a stepwise process in which coals are degraded to asphaltenes and then to oils via hydrogen atom transfer and carbon-carbon bond fragmentation processes as well as deoxygenation reactions. Adduction reactions of the aliphatic residua and the aromatic coal occur simultaneously. The reactivity of the coal, in particular its capacity to initiate free-radical chain reactions and to donate hydrogen atoms, appears to play a key role in this chemistry. © 1991, American Chemical Society. All rights reserved.