Short-contact-time coal liquefaction products

Processing Short-Contact-Time Coal Liquefaction Products... 

Short-Contact-Time Coal Liquefaction Products and the Initial Structure of Coal. Our own data and those from the literature indicate that no major changes take place in the different elements of coal structure under short-contact-time reaction conditions and at relatively low temperature. It is obvious, however, that fragmentation occurs by... 

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. 

Data Obtained from Solubilized Coal. We have found that the careful use of the structural information provided by short-contact-time coal thermal liquefaction products can give relevant information on coal structure. 

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. 

Short-contact time liquefaction products from bituminous coal... 

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 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. 

A corollary of this statement is the following If these polyaromatic or polycyclic saturated structures are present in the carbon skeleton of coal, they should be identified in the short-contact-time liquefaction products. The possibility of some isomerization reactions in the carbon skeleton cannot be excluded totally, but the most important fact is that no dramatic aromatization of hydroaromatic rings or saturation of aromatic rings takes place under these conditions. Many of the chemical functions also are stable under these conditions, especially the O, S, and N heterocyclic aromatic structures. Water formation by phenol dehydroxylation is minimal. In coal liquefaction under our conditions, even at long reaction times (up to 90 min) in the absence of an added catalyst, the -OH bonded to a monoaromatic ring is stable. Under the same conditions, dehydroxylation of polyaromatic phenols does occur (10). 

The data above show that the structure of short-contact-time products of coal liquefaction is indicative of the main characteristics of the carbon skeleton in coal itself, the distribution and abundance of the majority of heteroatomic functions, and the statistical distribution of the weak bonds in the parent coal. 

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