Transfer hydrogenation of heavy hydrocarbons with hydrogen-donor solvents

A process of thermally treating a highly viscous, heavy hydrocarbon comprising:

• preparing a hydrogen-donor solvent capable of dehydrogenation;
• mixing the heavy hydrocarbon and the hydrogen-donor solvent to form a slurry;
• heating the slurry such that the heavy hydrocarbon depolymerizes to form smaller fragments and wherein the hydrogen-donor solvent transfers hydrogen to the smaller fragments to prevent repolymerization of the smaller fragments;
• and
• cooling the product wherein the product comprises a hydrocarbon having a lower viscosity than a viscosity of the heavy hydrocarbon;
• wherein the heavy hydrocarbon is treated without using molecular hydrogen and an added catalyst.