Short-contact-time coal composition

In a study of short contact time coal liquefaction (109), in which major product fractions were examined with respect to their structure as well as their composition, the (nominal) high-molecular-weight product fractions of two similar subbituminous coals were found to possess radically different formal structures (cf. structure 6) one showed 73% and 60%, and the other showed 26% and H. 18%. Significantly, both fractions were deemed to closely resemble their respective precursor coals but to be slightly more aromatized than they. 

The significance of these calculations is that lower rank coals will require 5% lower conversion than higher rank coals for a given end product. Also, the more severe a coal is to be upgraded, the lower its conversion has to be in the initial phases of liquefaction. One very pertinent question to be addressed is whether or not coals can be converted to the levels shown in Figure 5 in a short contact time process. This paper will deal with that question as well as what compositional features of the coal and the solvent influence short contact time conversions. 

The Effect of Coal Composition on Short Contact Time Conversion... 

Product characterization from liquefaction has not been extensive. Phi 1p and Russell (95) have examined products by Py-GCMS from metal halide catalyzed hydrogenation of a vitrinite, alginite, and inertinite, each from a different source. They were able to correlate Py-GCMS results with reaction temperature. King, et al. (96) examined the short contact time liquefaction of macerals separated by DGC from a single hvB bituminous coal. They found correlations between density and reactivity and composition of the products. 

The overall products of coal conversion can also vary when reacted with solvents of different compositions. A combination of data from our earlier studies using solvents containing 40% tetralin and data from this project shows that in general all of the CO production ceased by about Rs = 50 or in other words, the short contact time regime. 

The elemental composition for the initial coal [for Monterey coal (2)] and its short-contact-time liquefaction products (defined as pyridine soluble) are shown in Table II. 

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