Liquefaction reactivity studies

Alkylation Studies. Several preliminary experiments were completed to compare the extent of alkylation obtained with our coal pretreatment method to that obtained with Sternberg and Liotta alkylation. Results for Wyodak coal are summarized in Table III. Clearly, our procedure provides a very mild alkylation treatment compared with the other two methods and does not appear to be sensitive to differences in alkyl chain length (methyl vs. propyl). The increase in THF solubiliw was also small this result again suggests only a small extent of alkylation and in addition, shows that only minimal ion exchange (for example Ca by H ) occurred in the coal mineral matter. The effect of each pretreatment method on low severity liquefaction reactivity is discussed in the next section. 

The effectiveness of these parameters is considered to depend heavily on the liquefaction conditions and the characteristics of the coal which is used. The better parameters can possibly be derived from both the amounts of the petrographic components %9 such as inerts ingredients %9 or reactive macerals % and their quality, such as H/C atomic ratio and so on. Consequently, it must be said that much further study is necessary to finally clarify the more comprehensive parameter. 

The present authors studied the solvolytic liquefaction process ( ,7) from chemical viewpoints on the solvents and the coals in previous paper ( 5). The basic idea of this process is that coals can be liquefied under atmospheric pressure when a suitable solvent of high boiling point assures the ability of coal extraction or solvolytic reactivity. The solvent may be hopefully derived from the petroleum asphaltene because of its effective utilization. Fig. 1 of a previous paper (8) may indicate an essential nature of this process. The liquefaction activity of a solvent was revealed to depend not only on its dissolving ability but also on its reactivity for the liquefying reaction according to the nature of the coal. Fusible coals were liquefied at high yield by the aid of aromatic solvents. However, coals which are non-fusible at liquefaction temperature are scarcely... 

Transalkylation might be expected another kind of the solvolitic reaction. However, the present results suggest low probability with alkylated pyrenes as suggested by the NMR analyses. Instead, the increased polarity by alkyl group or the enhanced reactivity of the carbonization precursor from alkylpyrene, especially ethylpyrene, may be responsible for a considerable liquefaction yield. The recovery of the solvent becomes difficult by its latter conversion as observed in the present study. 

Liquefaction of inertinites is not always as poor as the name would imply. Table III shows some conversion data taken from Ref. (91), where conversion is defined as ethyl acetate solubles plus gases. The low reflecting Australian fusinites and seini-fusinites are reactive compared to the Illinois samples. This has been confirmed by a recent study on Australian inertinites (93) where it has been found that at higher temperatures (450 C) up to 54% of the inertinite was calculated to be converted. This difference between the Australian and North American inertinites has also been observed in carbonization reactions (94). 

The first examples of materials that supported liquid clathrate phase formation, in contact with aromatic hydrocarbons, were highly reactive air-sensitive salts containing alkylaluminum anions, first described by At-wood. " Their applications for separations of aromatics from hydrocarbons and in coal liquefaction were extensively explored. However, a drawback of the initial systems studied was their air-sensitivity and reactivity. 

Since the initial discovery of liquid clathrate systems, hundreds of compounds having the structure M[Al2R6X] were found to exhibit liquid clathrate behavior.While these highly reactive air-sensitive salts are useful in such applications ranging from separations of aromatics from hydrocarbons to coal liquefaction, their air-sensitivity and reactivity posed drawbacks to further study. 

The relationship between coal composition and hydrogenation reactivity has been studied extensively and coal with less than 85% w/w carbon (daf) made poor liquefaction feedstocks. It has been suggested that coal reactivity is related to rank (Francis, 1961). Coal is, in actual fact, a hydrogen-deficient organic natural product having an atomic hydrogen/carbon ratio of approximately 0.8 compared with an atomic hydrogen/carbon atomic ratio of 1.4 1.8 for various crude oils, heavy oil, and bitumen (Table 12.1). 

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