Theoretical modeling of coliquefaction reactions of coal and polymers

Abstract

Differences have been found in the coliquefaction of polyethylene and polypropylene with Black Thunder coal in the presence of a zeolite catalyst. Conversion and oil yields are higher with the polypropylene-coal system while preasphaltene and asphaltene products are higher in the presence of polyethylene. In an attempt to explain the differences in coliquefaction behavior of the two polymers we have begun quantum chemical studies of the two systems by looking at possible differences in cracking of the two polymers and by investigating hydrogen transfer reactions and addition reactions between toluene and polymer fragments. We find that addition of toluene to the fragments is potentially more important in polyethylene than in polypropylene. This addition leads to higher molecular weight products. In addition, hydrogen transfer to benzylic cations from the polymers occurs at slightly longer distances with polypropylene, indicating a greater synergism in this case than with polyethylene.