Possible Hydride Transfer in Coal Conversion Processes

The conversion of coal to liquid fuels is usually carried out in the presence of an H-donor solvent (H-don) such as Tetralin. The chemical route commonly suggested for the process is in which there is initial thermal homolysis of sufficiently weak bonds in the coal structure to yield radical sites. These reactive sites are then "capped" by transfer of hydrogen atoms from the donor solvent. We will discuss here the chemistry of this process, including detailed consideration of the thermochemistry of Steps 1 and 2 above. We will then present some of our recent data, which suggest that there may be an ionic component in the process. Background Step 1 above requires that there be bonds in the coal that are weak enough to break in appropriate numbers at conversion temperatures and times. Table I displays some kinetic data for the cleavage of benzylic bonds in a series of