Inferences regarding the nature of solvent-refined coal (SRC)

Preparative gel permeation chromatographic separation of solvent refined coal

“…The SRC under examination possess 97-98% solubility in THF (17). Figure 3 shows a typical separation of this THFsoluble portion obtained on the column described in Figure 2.…”

“…While a separation based somewhat on size and polarity may at first glance appear desireable, this is not the case for coal liquid separations. Since the conversion to coal liquids can be generally thought of as a "depolymerization" process and NMR studies (26) reveal random and limited functionality and our goal is to identify the bonds cleaving during the conversion, a pure size separation was most desirable. Similar separations on Sephadex employing CHCI3 were not possible due to severe "back pressure" problems associated with the glass column design.…”

“…The variations of PGC data were attributed to several factors such as instrument design, pyrolyzer geometry, and temperature rise time (15)(16)(17). However, there are still other considerations which deserve special attention.…”

Matrix electron nuclear double resonance studies of the proton environment of the radical in natural and solvent-refined coal

“…For a disordered polycrystalline matrix the average ENDOR response is obtained by averaging over all orientations and summing the contributions from nuclei located at different distances from the umpaired electron according to -f (5+(r,•, ft, ) + -{ , , ))ß 2dr (5) In this model no assumptions about the strengths of Hi and Hi are made. The model also explicitly includes both direct and cross relaxation mechanisms and might provide a possibility of determining which relaxation mechanisms are operative in the system.…”

“…The pulverized raw coal is mixed with a high boiling point aromatic solvent, hydrogen is added, and the dissolution takes place at ~450 °C. 5 The solvent is then removed in a distillation column. The residue is the solvent-refined coal (SRC).…”