Akademik Veri Yönetim Sistemi
ENERGY & FUELS, cilt.21, sa.4, ss.2216-2225, 2007 (SCI-Expanded)
Two high-sulfur Turkish coals (Mengen and Kangal) and an asphaltite (Avgamasya) were liquefied with and without the catalyst precursors ammonium heptamolybdate (AHM) and ammonium tetrathiomolybdate (ATTM) at 300, 350, 400, and 450 degrees C. Blends of these coals with the asphaltite were also liquefied using ATTM. Effective conversions of both coals into oils and into asphaltene and preasphaltene fractions were achieved with both catalyst precursors, although ATTM was more effective than AHM. Maximum conversion for Mengen coal with ATTM (89.2%) was achieved at 400 degrees C, although the maximum yield of oils (56.9%) was obtained at 450 degrees C. Kangal, in the presence of ATTM, gave maximum conversion (87.7%) at 400 degrees C; the corresponding oil yield (49.6%) was not much less than that obtained at 450 degrees C (49.9%). Some retrogressive reactions toward the formation of aromatics were observed during liquefaction at 450 degrees C in the presence of AHM or ATTM with both coals. Also, using these catalyst precursors results in effective hydrogenation of two-ring or higher condensed aromatics and effective hydrogenolysis of the alicyclic part of hydroaromatic structures. On the other hand, these catalyst precursors do not provide effective saturation of monoaromatic rings, although the use of ATTM yielded partial reduction of these compounds. The distribution of main product fractions obtained from these reactions and the detailed analysis of oils obtained are reported here.