Non-aqueous enzymatic solubilization of coal-derived materials

The utilization of enzymes in non-aqueous solvents was explored for the conversion of coal-derived materials to oil-soluble derivatives for use as fuels. A novel three-step process was developed:

1. (1) an initial low-severity conversion to a form that is soluble or dispersible in a polar solvent;

2. (2) formation of an alcohol substrate with a high activity for subsequent enzymatic processing;

3. (3) lipase-catalysed transesterification to a product that is soluble in hydrocarbon solvents.

The process was successful for the conversion of a first-stage liquefaction product from Wyodak subbituminous coal to an acylated product, about half of which is soluble in hexane and the remainder in toluene. Coals, humic acids and several other higher-molecular-weight coal liquefaction products, such as Chemcoal, and their derivatives inhibited the lipases, and thus the alcohol intermediates from these precursors were converted in 0–5% yields to acylated products.