A process to upgrade heavy oil and convert the heavy oil into lower boiling hydrocarbon products is provided. The process employs a catalyst slurry comprising catalyst particles with an average particle size ranging from 1 to 20 microns. In the upgrade process, spent slurry catalyst in heavy oil is generated as an effluent stream, which is subsequently recovered/separated from the heavy oil via membrane filtration. In one embodiment, residual hydrocarbons, i.e., heavy oil and solvent employed in the filtration for the heavy oil extraction are removed from the catalyst particles with the use of a cleaning solution comprising a sufficient amount of at least a surfactant for removing at least 90% of the hydrocarbons from the catalyst particles. In one embodiment, ultrasonic cleaning is also used for the removal of hydrocarbons. In another embodiment, a plasma source is employed for the volatization of the hydrocarbons. Valuable metals can be recovered from catalyst particles for subsequent re-use in a catalyst synthesis unit, generating a fresh slurry catalyst.